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DESCRIPTION This report gives technical guidelines for radio-iodine monitoring following a nuclear incident. Monitoring aspects addressed include the choice of detectors, the calibration and measurement process, factors affecting measurements, measurement uncertainties, the preparation of equipment and measurement locations, the measurement time, the measurement of very young children, management of results and measurements performed by members of the public. This latter point is addressed by making recommendations to professionals to enable them to train and inform citizens. Interpretation of measurements is addressed by providing data on doses per unit measurement, enabling the direct conversion of a measurement into thyroid doses and committed effective doses. The information provided can be used to calculate doses for different age groups, for the embryo or foetus, and for different radio-iodine isotopes. Interpretation of measurements following iodine prophylaxis is also addressed, as well as the case of doses from intakes of short-lived radio-iodine isotopes that cannot usually be measured in the thyroid.
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OPERRA Deliverable D5.31
CAThyMARA report: Technical guidelines for radio-
iodine in thyroid monitoring
DESCRIPTION
This report gives technical guidelines for radio-iodine monitoring following a nuclear incident.
Monitoring aspects addressed include the choice of detectors, the calibration and measurement
process, factors affecting measurements, measurement uncertainties, the preparation of
equipment and measurement locations, the measurement time, the measurement of very young
children, management of results and measurements performed by members of the public. This
latter point is addressed by making recommendations to professionals to enable them to train
and inform citizens. Interpretation of measurements is addressed by providing data on doses
per unit measurement, enabling the direct conversion of a measurement into thyroid doses and
committed effective doses. The information provided can be used to calculate doses for different
age groups, for the embryo or foetus, and for different radio-iodine isotopes. Interpretation of
measurements following iodine prophylaxis is also addressed, as well as the case of doses from
intakes of short-lived radio-iodine isotopes that cannot usually be measured in the thyroid.
Due date: May 2017
Actual submission date: May 2017
Status: Final
Nature Report
Dissemination
level PU (Public)
Lead beneficiary
organisation PHE
Authors
G Etherington, J Marsh, D Gregoratto, M Youngman, D Franck,
A L Lebacq, M Isaksson, J Ośko, J M Gómez-Ros, M A Lopez, P
Fotjík, I Malatova, P Zagyvai, O Monteiro Gil, P Teles, P Vaz, M
A Saizu, T Vrba, V Berkovskyy, G Ratia, Y Bonchuk, D Broggio
Contributors
G Etherington, J Marsh, D Gregoratto, M Youngman, D Franck,
A L Lebacq, M Isaksson, J Ośko, J M Gómez-Ros, M A Lopez, P
Fotjík, I Malatova, P Zagyvai, O Monteiro Gil, P Teles, P Vaz, M
A Saizu, T Vrba, V Berkovskyy, G Ratia, Y Bonchuk, D Broggio
Approval WP5 leader Lara Struelens:
OPERRA coordinator Jean-René Jourdain:
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TABLE OF CONTENTS
I. INTRODUCTION............................................................................................................................................. 5
II. MEASUREMENTS OF RADIO-IODINE IN THE THYROID FOR ADULTS AND CHILDREN ..................................... 8
II.1 MONITORING EQUIPMENT ................................................................................................................................. 9
II.1.1 Spectrometric instruments .................................................................................................................... 9
II.1.2 Non-spectrometric instruments........................................................................................................... 11
II.2 CALIBRATION AND DETECTION LIMITS ................................................................................................................. 13
II.2.1 Definition of calibration factors and measurement process ............................................................... 13
II.2.2 Characteristics of phantoms suitable for radio-iodine in thyroid measurements ............................... 14
II.2.3 Neck to detector distances for calibration and subject measurements .............................................. 17
II.2.4 Detection limit and minimum assessable dose.................................................................................... 19
II.3 MEASUREMENT PREPARATION AND PRACTICE ...................................................................................................... 23
II.3.1 Location of monitoring and required equipment ................................................................................ 23
II.3.2 Maintenance of monitoring devices.................................................................................................... 24
II.3.3 External contamination monitoring .................................................................................................... 25
II.3.4 Protection of instruments against contamination............................................................................... 25
II.3.5 Background characterisation .............................................................................................................. 25
II.3.6 Measurement duration and measurement time ................................................................................ 26
II.3.7 Measurements of very young children ............................................................................................... 27
II.4 MEASUREMENT UNCERTAINTIES AND MEASUREMENT BIAS ..................................................................................... 30
II.4.1 Uncertainties du e to counting statistics ............................................................................................ .. 30
II.4.2 Uncertainties due to detector positioning ........................................................................................... 30
II.4.3 Bias due to radio-iodine activity in organs other than the thyroid...................................................... 30
II.4.4 Bias due to the age of the measured person ....................................................................................... 30
II.4.5 Uncertainties associated with the calibration phantom ..................................................................... 30
II.4.6 Uncertainties due to variability in thyroid mass .................................................................................. 31
II.5 RESULTS MANAGEMENT ................................................................................................................................... 31
II.5.1 Registration ......................................................................................................................................... 31
II.5.2 Collecting measurement results .......................................................................................................... 31
II.5.3 Records ........................................................................................................ ........................................ 32
II.5.4 Reporting ........................................................................................................ ..................................... 32
II.6 THYROID MEASUREMENTS MADE BY MEMBERS OF THE PUBLIC ................................................................................ 34
REFERENCES FOR SECTION II .................................................................................................................................... 39
III GUIDELINES ON DOSE ASSESSMENT FOR ADULT, CHILD, EMBRYO AND FOETUS FROM MEASUREMENTS OF
RADIOIODINE IN THE THYROID GLAND .......................................................................................................... 41
III.1 INTRODUCTION .............................................................................................................................................. 41
III.2 INPUT INFORMATION ...................................................................................................................................... 41
III.3 THYROID DOSE FROM INTAKE OF I-131 ESTIMATED BASED ON THE I-131 CONTENT IN THE THYROID GLAND................... 43
III.4 EFFECTIVE DOSE FROM INTAKE OF I-131 ESTIMATED BASED ON THE I-131 CONTENT IN THE THYROID GLAND ................. 45
III.5 TOTAL DOSE FROM RADIO-IODINE ISOTOPES AND TE-132 PRESENT IN THE SOURCE TERM OF A LIGHT WATER REACTOR
ESTIMATED BASED ON THE DOSE FROM I-131............................................................................................................. 48
III.6 DOSES FROM INTAKE OF RADIO-IODINE ISOTOPES AND TE-132 ESTIMATED BASED ON MEASURED I-131 AND I-132
CONTENTS IN THE THYROID GLAND ........................................................................................................................... 49
III.7 DOSE TO THE FOETAL THYROID GLAND ESTIMATED BASED ON THE I-131 CONTENT IN THE MATERNAL THYROID GLAND..... 54
III.8 DOSES TO THE FOETAL THYROID GLAND ESTIMATED BASED ON THE I-131 AND I-132 CONTENT IN THE MATERNAL THYROID
GLAND................................................................................................................................................................. 58
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III.9 SCOPE OF APPLICABILITY.................................................................................................................................. 60
III.9.1 Quantities used in this section............................................................................................................ 60
III.9.2 Ranges of parameter values describing the conditions of exposure .................................................. 60
III.9.3 Thyroid blocking ................................................................................................................................. 62
III.9.4 High dose estimates ........................................................................................................................... 63
III.9.5 External background and contamination of the skin and clothes ...................................................... 64
III.10 UNCERTAINTIES IN DOSE FOR ADULTS AND CHILDREN ASSESSED FROM MEASUREMENTS OF RADIO-IODINE IN THE THYROID
.......................................................................................................................................................................... 64
III.10.1 Material- specific parameters and route of intake........................................................................... 64
III.10.2 Time of intake................................................................................................................................... 64
III.10.3 Thyroid mass .................................................................................................................................... 64
III.10.4 Age group .................. ....................................................................................................................... 64
III.10.5 Dietary intake of stable iodine.......................................................................................................... 65
III.10.6 Hypothyroidism and hyperthyroidism .............................................................................................. 65
REFERENCES FOR SECTION III................................................................................................................................... 65
APPENDIX A. FACTORS AFFECTING THE MEASUREMENT OF RADIO-IODINE IN THE THYROID FOR ADULTS AND
CHILDREN....................................................................................................................................................... 67
A.1 SIMULATION DETAILS....................................................................................................................................... 67
A.1.1 Voxel phantoms................................................................................................................................... 67
A.1.2 Detectors ...................................................................................................... ....................................... 67
A.1.3 Mo nte Carlo simulations ..................................................................................................................... 68
A.2 EFFICIENCY AS A FUNCTION OF COUNTING DISTANCE.............................................................................................. 68
A.3 EFFICIENCY AS A FUNCTION OF THYROID VOLUME.................................................................................................. 70
A.4 EXTRA-THYROIDAL CONTRIBUTION ..................................................................................................................... 71
REFERENCES FOR APPENDIX A................................................................................................................................. 72
APPENDIX B. FACTORS AFFECTING THYROID DOSE ASSESSMENT: DIETARY INTAKE OF STABLE IODINE AND
THYROID BLOCKING ....................................................................................................................................... 74
B.1 DIETARY INTAKE OF STABLE IODINE..................................................................................................................... 74
B.2 THYROID BLOCKING ......................................................................................................................................... 74
B.3 CORRECTION OF THE ICRP-BASED DOSE PER CONTENTFUNCTIONS WITH THE USE OF A SIMPLE 3-COMPARTMENT MODEL
ADOPTED FOR SIMULATION OF THYROID BLOCKING...................................................................................................... 75
REFERENCES FOR APPENDIX B................................................................................................................................. 77
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I. INTRODUCTION
Radio-iodine intake is one of the major contributors to the radiation dose that may be received by
members of the public after a nuclear power plant (NPP) accident. Examples of such events include
the Chernobyl accident in 1986 and the Fukushima accident in 2011. An intake may occur by
inhalation of radio-iodine vapour or particulate material in air, or by ingestion of radio-iodine present
in foodstuffs (including milk) and in drinking water. Depending on the accident scenario, multiple
intakes may take place. All isotopes of iodine (both radio-isotopes and stable isotopes) concentrate
almost exclusively in the thyroid gland, which is positioned at the base of the front of the neck
typically with an overlying tissue thickness between 0.4 and 1.5 cm.
This document provides technical guidelines for large-scale individual radiation monitoring of
members of the public for radio-iodine intakes. Special emphasis is placed on individual monitoring
of children. The term “individual monitoring” includes both the measurement of activity of radio-
iodine isotopes in the thyroid (expressed in units of Becquerels), and the assessment of radiation
doses for the person measured from the results of these measurements (expressed in Grays or
Sieverts). The absorbed dose in the thyroid is expressed using Grays, while the equivalent dose to the
thyroid and the committed effective dose for a person are expressed using Sieverts. The terms
Becquerel, Gray and Sievert are often abbreviated using the symbols Bq, Gy or Sv. Doses are often
expressed in milli-Grays (mGy) or milli-Sieverts (mSv).
Health monitoring is not addressed in this document.
The target audience primarily comprises the technical staff responsible for planning and performing
radio-iodine in thyroid measurements in the event of a radiation emergency involving a significant
release of radionuclides.
These technical guidelines constitute one of the outcomes of the CAThyMARA project, and are
derived from the results of the Work Packages of the projecti,ii,iii,iv,v. The technical information and
data presented here will allow the implementation of a monitoring strategy according to the
guidelines for development of monitoring strategiesvi issued during the CAThyMARA project.
The technical guidelines specifically take into account information on existing plans and means at the
European level, together with judgements made regarding their adequacy for monitoring thousands
of people in the event of a severe nuclear or radiological accident or other emergency. During the
CAThyMARA project, a survey was conducted in 18 European countries, and information was
obtained on thyroid monitoring capability in the event of a large scale nuclear accident in Europe and
neighbouring countries. In addition, a literature review of relevant international and national
recommendations on radio-iodine monitoring in the thyroid was performedi. It was found that there
is a lack of detailed procedures for monitoring members of the public for external contamination and
internal contamination, including radio-iodine contamination of the thyroid. There is also a lack of
harmonisation on the application of international recommendations, particularly with respect to the
decision-making process for initiating thyroid monitoring. Iodine-in-thyroid monitoring capacity
varies widely in different European countries, ranging from a few tens to several thousand people
who could be monitored during one day. Numbers of trained staff in different EU countries also vary
widely, from a few to over 100. Most institutions have equipment for thyroid monitoring, but only a
few have specific equipment for children. Most institutions are able to perform dose calculations,
although some can only measure internal contamination. About half can perform dose calculations
for children. Only a few can take into account thyroid blocking when assessing doses. Almost all
institutions participate in emergency exercises, but only about one third include thyroid monitoring
in exercises. Few institutions have participated in measurement or dose assessment intercomparison
exercises. About half reported that there is interest from members of the public in carrying out their
own thyroid measurements. However, it was reported that specialists are reluctant to take these
measurements into account.
6
Adoption of the CAThyMARA guidelines will allow reliable and robust procedures for emergency
iodine-in-thyroid monitoring to be established in advance of any radiation emergency. Their adoption
will also promote harmonisation of emergency response procedures across the EU. This will be an
important step towards establishing a sustainable network of organisations and people in the EU
with responsibilities for emergency personal monitoring.
Section II.1 provides guidelines and recommendations on monitoring equipment, specifically on the
choice between spectrometric and non-spectrometric instruments, the relative merits of different
types of semiconductor and scintillation detectors, detector size, shielding and collimation. Advice is
also provided on selection of suitable non-spectrometric instruments.
Section II.2 provides guidelines and recommendations on calibration procedures, specifically on the
use of energy-dependent counting efficiency functions and calibration factors to determine the
radio-iodine activity in the thyroid, characteristics of thyroid phantoms suitable for calibration of
radio-iodine in thyroid measurements, the use of “mock" 131I calibration sources, and detector
positioning. Calculation of measurement DLs and the corresponding minimum doses that can be
assessed are also addressed.
Section II.3 provides guidelines and specific recommendations on plans and preparations for
monitoring, monitoring locations, the ancillary equipment needed in addition to monitoring
instruments, maintenance and testing of monitoring instruments, external contamination
monitoring, protection of instruments against contamination with radioactive materials,
characterisation of the measurement background, measurement duration, measurement time (after
intake), and measurements on young children.
Section II.4 provides information on uncertainties due to counting statistics, uncertainties due to
detector positioning, bias in the measurement result due to radio-iodine activity in organs other than
the thyroid, bias due to the age of the person measured, uncertainties associated with the calibration
phantom, and uncertainties due to variability in thyroid mass and depth.
Section II.5 provides guidelines and recommendations on management of results, specifically on
registration of people before commencement of monitoring, monitoring records and reporting of
monitoring results.
Section II.6 provides guidelines and specific recommendations relating to thyroid measurements
made by members of public. Specific topics addressed are: the need for training and quality
assurance, issues arising when members of the public make their own measurements, advantages
arising from members of the public making their own measurements, identification of suitable
instruments, performing simple function checks, making simple measurements, avoiding erroneous
results, reporting results and interpreting results.
An appendix to Section II, derived from the work undertaken during this projectiv describes the main
factors affecting measurements of radio-iodine in the thyroid for adults and children.
Section III provides guidelines on the assessment of committed absorbed dose to the thyroid and
committed effective dose for an adult, child, embryo or foetus, from measurements of radioiodine in
the thyroid. The estimation of doses from intakes of other radio-iodine isotopes from measurements
of 131I in the thyroid is also addressed. An appendix to Section III addresses dose assessment in the
event of administration of stable iodine for the purpose of thyroid blocking.
iMonteiro Gil O et al. 2017 Report of the CAThyMARA project. Report of WP2 about existing plans and means,
including comparison with international recommendations. Available on the MELODI web site
(http://www.melodi-online.eu/) and on ResearchGate (https://www.researchgate.net/)
7
ii Lebacq A-L et al. 2017 Report of WP3 about inter-comparison results for mobile units. Report of the
CAThyMARA project Available on the MELODI web site (http://www.melodi-online.eu/) and on ResearchGate
(https://www.researchgate.net/)
iii Isaksson M et al. 2017 Report of WP4 about inter-comparison results for non-trained responders. Report of
the CAThyMARA project. Available on the MELODI web site (http://www.melodi-online.eu/) and on
ResearchGate (https://www.researchgate.net/)
iv Gómez-Ros J-M et al. 2017 Report of WP5 about Monte Carlo calculated age dependent calibration
factors.Report of the CAThyMARA project. Available on the MELODI web site (http://www.melodi-online.eu/)
and on ResearchGate (https://www.researchgate.net/)
vVrba Tet al. 2017. Report of WP6 about dose assessment tools. Report of the CAThyMARA project. Available
on the MELODI web site (http://www.melodi-online.eu/) and on ResearchGate
(https://www.researchgate.net/)
vi Etherington G et al. 2017. Guidelines for development of monitoring strategies and derivation of reference
levels. Report of the CAThyMARA project. Available on the MELODI web site (http://www.melodi-online.eu/)
and on ResearchGate (https://www.researchgate.net/)
8
II. MEASUREMENTS OF RADIO-IODINE IN THE THYROID FOR ADULTS
AND CHILDREN
Section II.
The topics for which technical guidelines are provided are as follows:
Section II.1: Monitoring equipment
a) Whether spectrometric or non-spectrometric instruments are preferred
b) The use of spectroscopic instruments
c) The relative merits of different types of semiconductor and scintillation detectors
d) Detector size
e) Shielding and collimation
f) The use of non-spectroscopic instruments
g) Choice of non-spectrometric instrument
Section II.2: Calibration and detection limits
a) The use of energy-dependent counting efficiency functions and calibration factors to
determine the radio-iodine activity in the thyroid
b) Characteristics of thyroid phantoms suitable for calibration of radio-iodine in thyroid
measurements
c) Use of “mock" 131I calibration sources
d) The optimum distance between the detector and the front of the neck
e) Calculation of detection limits
f) Minimum doses that can be assessed
Section II.3: Measurement preparation and practice
a) Plans and preparations for monitoring
b) Monitoring locations
c) Ancillary equipment (in addition to monitoring instruments)
d) Maintenance and testing of monitoring instruments
e) External contamination monitoring
f) Protection of instruments against contamination with radioactive materials
g) Characterisation of the measurement background
h) Measurement duration
i) Measurement time (after intake)
j) Measurements on young children
Section II.4: Measurement uncertainties and measurement bias
a) Uncertainties due to counting statistics
b) Uncertainties due to detector positioning
c) Bias due to radio-iodine activity in organs other than the thyroid
d) Bias due to the age of the person measured
e) Uncertainties associated with the calibration phantom
f) Uncertainties due to variability in thyroid mass and depth
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II.1 Monitoring equipment
II.1.1 Spectrometric instruments
The monitoring of workers for internal contamination is usually performed under laboratory
conditions with spectrometric equipment. However, the monitoring of members of the public after a
nuclear accident would only rarely be performed under laboratory conditions. As a result,
background levels of gamma radiation will be substantially higher. Spectrometric instruments are
preferred because they can discriminate radionuclide gamma peaks from the diffuse gamma
background, and because they can identify and differentiate between gamma-emitting radionuclides.
As their efficiency is relatively high, these instruments are the most preferred type for precise
characterisation and quantification of the retained activity in the body or in an organ.
A measurement is preferably carried out by placing the instrument in close contact to the neck, at
the position of the thyroid gland. The instrument reading is then converted to 131I activity in thyroid
by means of a pre-determined calibration factor (Section II.2). Difficulties may arise with the use of
spectrometric equipment due to the limited number of available instruments and the fact that they
have to be mobile. In some countries, mobile units equipped with spectrometric instruments make it
possible to approach laboratory conditions [Dantas et al. 2010, Franck et al. 2012].
Although availability of instruments is the first criterion in the choice of specific instruments in a
radiation emergency, when it comes to the measurement of 131I in the thyroid using spectrometric
instruments, the following aspects are also important:
Type of detector crystal (the crystal is the active element of the detector)
Size of the detector crystal
Shielding/collimation
Section II.
The topics for which technical guidelines are provided (continued):
Section II.5: Results management
a) Registration of people before commencement of monitoring
b) Measurements required
c) Monitoring records
d) Reporting of monitoring results
Section II.6: Thyroid measurements made by members of public
a) Target audience for the recommendations made
b) Purpose of the recommendations
c) The need for training and quality assurance
d) Issues arising when members of the public make their own measurements
e) Advantages of members of the public making their own measurements
f) Identification of suitable instruments
g) Performing simple function checks
h) Making simple measurements
i) Avoiding erroneous results
j) Reporting results
k) Interpreting results
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Type of detector crystal
Three types of spectrometric detectors are most commonly used for gamma-ray spectrometry. All of
them can be used for the measurement of radio-iodine in the thyroid.
Germanium (Ge) detectors are semiconductors. They have the big advantage that energy
resolution is very good. This allows separation of peaks in the spectrum that are close
together, which is necessary when contamination includes radionuclides additional to 131I, for
example 132I or 137Cs.
Germanium detectors need to be cooled either with liquid nitrogen or with an electrical
cooling system. Supply of liquid nitrogen can be a problem in field conditions. However,
electric cooling considerably increases the price of the detector.
Sodium-iodide (NaI(Tl)) detectors are scintillators. They don’t need to be cooled but they
have the disadvantage of poor energy resolution. They are adequate as long as only one
radionuclide is present, but nuclear accidents can result in the release of many radionuclides
in addition to 131I. They don’t need to be cooled but are preferably operated in an air
conditioned and temperature-controlled room as their energy calibration can change with
temperature variations.
Lanthanum bromide (LaBr3) detectors are scintillators that are relatively new to the thyroid
monitoring application. Their big advantages are a better energy resolution compared to
NaI(Tl) detectors and they don’t need to be cooled.
Other detector types include cadmium zinc telluride (CZT) (a semiconductor), and caesium iodide
(CsI) (a scintillator). Both are available with small crystal sizes, although their use for in vivo
monitoring is not very common. Because of their small size they have a lower efficiency but they
could be used to monitor the thyroid of very young children (Section II.3.7). They can be operated at
room temperature and CZT detectors have a better energy resolution than NaI(Tl) detectors.
Size of crystal
The size of the crystal, especially the diameter, influences the efficiency of the measurement. A small
crystal has a smaller efficiency but is more convenient for children because it can be positioned
closer to the thyroid. As the diameter increases, the very accurate positioning of the detector relative
to the thyroid becomes less important. However, the environmental background contribution to the
measured spectrum also increases with detector size and this affects the Detection Limit (DL). The
DL increases with the environmental background count rate but decreases with the efficiency of the
detector. Generally, the DL decreases with increasing detector volume because of the higher
efficiency, but not as quickly as would be expected from a simple calculation due to the increased
background contribution, especially if the monitored subject induces a significant background
contribution.
Based on the recommendations on detectors cited in [Monteiro Gil et al. 2017], an NaI(Tl) detector
with a diameter between 1” and 2” (i.e. 25 to 51 mm) and a thickness in the same range is a typical
and adequate size. For Ge detectors, commonly-used instruments are rather larger, and a diameter
between 50 and 70 mm and a thickness in the same range or smaller is recommended.
Shielding and collimation
Shielding and collimation of the detector can be used to reduce measured background radiation
levels. The purpose is to allow only radiation emitted by the thyroid to enter the crystal of the
detector, as far as possible. These measures are not mandatory for the performance of useful
measurements. However, if shielding and/or collimation are available, they will have a positive
impact on the reliability of measurements, and their application should be considered.
Shielding of the detector allows only the radiation entering the front window to reach the
detector crystal. As radiation arriving at the side of the crystal will normally not come from the
thyroid, it is advantageous to block this radiation from reaching the detector. The resulting
decrease in background radiation reduces the DL.
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Collimation can be done by adding or increasing the shielding between the detector and the
neck of the person to be measured. As well as preventing environmental radiation from
reaching the front of the detector, contributions from iodine or other radionuclides in the rest of
the body are also excluded.
Gamma camera systems
Gamma cameras are not used by radiation protection specialists involved in internal contamination
monitoring. However, in several countries, investigations have been conducted of the potential use
for large scale population screening of the facilities of imaging or nuclear medicine departments in
hospitals [Dantas et al. 2007, Anigstein et al. 2010, Ören et al. 2016, Nyander Poulsen et al. 2014].
The measurement of 131I in the thyroid with gamma cameras is common practice in nuclear medicine
departments; the energy window is thus already set up for most devices. The main challenge is to
detect thyroid activity far below the usual activities used in nuclear medicine, and for that purpose it
is recommended to remove the collimator of the gamma camera.
II.1.2 Non-spectrometric instruments
General
The use of portable dose rate or count rate meters (see below) offers an alternative to the preferred
gamma-ray spectrometry technique. The technique is less sensitive and less accurate, but uses
readily available instruments that do not require the special expertise that is needed for the use of
spectrometric equipment. Due to their relative low cost and ease of use, such instruments can be
used by citizens to carry out their own measurements (Section II.6).
A measurement is preferably carried out by placing the instrument in close contact to the
neck, at the position of the thyroid gland. The instrument reading is then converted to 131I activity in
thyroid by means of a pre-determined calibration factor (Section II.2.1). For dose rate meters, the
instrument readout in Sv/h can also be compared to the operational intervention level, OIL8 (IAEA,
2017), if set in national emergency response plans.
Instruments widely used for environmental measurements are envisaged to be utilised for
dose rate measurements over the thyroid in emergency situations. In dose rate mode, such
instruments are mostly calibrated to show ambient dose equivalent rate ܪ̇(10)[e.g. Sv·h-1],
exposure rate [e.g. mR·h-1] or absorbed dose rate [e.g. Gy·h-1]. The dose rate measurement over the
thyroid must be converted to thyroid activity with an appropriate calibration factor (Section II.2.1).
Examples of instruments
Predominantly, gas-filled or scintillation detectors are used in contemporary instruments. Affordable
instruments used by members of the public are equipped almost exclusively with a Geiger-Müller
tube (GM tube) due to their less demanding technical design. Most professional instruments have
the capability to store measurement data.
Instruments with GM tubes can be either dose rate or count rate measuring instruments.
Pulses from the GM tube are fed to a scaler (an electronic device that records the number of counts
registered in a pre-set period) and the reading is displayed as a count rate, counts per second (cps).
The reading may alternatively be displayed as a dose rate, provided that the instrument has been
calibrated for dose rate measurements at a calibration laboratory.
Dose rate meters may also be equipped with NaI(Tl) or organic (plastic) scintillation detectors
and operated in event-mode (i.e. counting mode) similar to a GM tube based instrument. A
scintillation detector generally has a higher sensitivity than a GM tube but also greater energy
dependence. The dose rate reading will be strictly valid only at the photon energy used for the
calibration of the instrument (this is also the case for instruments with GM tubes). An example of a
scintillation detector-based instrument is the Automess 6150AD-b probe, connected to the Automess
12
6150AD base unit. The probe consists of a cylindrical 3’’ by 3’’ organic scintillator, and the equipment
shows the reading as ܪ̇(10), between 100 nSv·h-1 and 0.1 mSv·h-1.
The Berthold LB 124 contamination monitor is equipped with a xenon-filled proportional
counter tube. Some alpha/beta contamination monitors are sufficiently sensitive to the dose rate
over the thyroid, but possible neck surface contamination by beta-emitting radionuclides could
interfere with the thyroid gamma-dose rate measurement.
The 900 series Mini-Monitor from ThermoFisher Scientific can be equipped with an NaI(Tl)
probe (Type 44A) with 2.5 mm thickness. This instrument shows the reading in cps.
The Canberra InSpector 1000 has an external NaI(Tl) probe and can be operated in dose rate
mode or spectrometric mode. At relatively high dose rates (17 Sv h-1) the instrument switches from
the NaI(Tl) probe to the GM tube that is built into the InSpector unit. Care should be taken therefore
when high thyroid dose rates (including the background) are detected corresponding to activities
above about 1 MBq of 131I in the thyroid. This could lead to critical underestimation of the thyroid
activity if the instrument has not been calibrated for the high dose rate range.
For portable instruments within the category of "legally controlled measuring instruments",
the technical standard IEC 60846-1:2009 is applicable [IEC, 2009]. This international standard has
been adopted at European [EN 60846-1:2014] and national levels (BS, DIN, etc.). Therefore,
requirements of this technical standard on radiation, electrical, mechanical, and environmental
characteristics should be consulted when choosing suitable instruments.
For the specific application of dose rate measurements over the thyroid, certain
requirements on the size of a detector active volume are applicable. Requirements for (i) the
effective window area of the detector and (ii) the detector’s response in terms of calibration factor
values are given by the IAEA and allow IAEA’s operational intervention level for thyroid monitoring
(OIL8) to be applied. Nevertheless, other instrument sizes may be employed provided that a specific
OIL8 value is derived for those instruments. This can be achieved by performing a calibration with a
suitable thyroid phantom containing radio-iodine (Section II.2.2).
Sensitivity required
For environmental dose rate meters, a lower limit of 0.03 μSv·h-1 is specified for dose rate range [IEC,
2015]. Instruments with a lower limit of 0.1 μSv·h-1 also have sufficient sensitivity to detect dose rates
at the operational intervention level, OIL8 (IAEA, 2017).
13
II.2 Calibration and detection limits
II.2.1 Definition of calibration factors and measurement process
The results of measurements of radio-iodine in the thyroid made with spectrometric or non-
spectrometric instruments are converted to radio-iodine activities using an energy-dependent
counting efficiency or a calibration factor, obtained by making an equivalent measurement on a
calibration phantom. A calibration phantom is a surrogate person, or part of a person, that is
constructed to allow placement of radionuclides in a geometry approximating internal distributions
of the radionuclide [ISO 2010a]. Only a brief account is given here; more details can be found in
[ICRU 2003].
Section II.1. Monitoring equipment
Recommendations
i. Spectrometric instruments are preferred over non-spectrometric instruments, because
they can discriminate radionuclide gamma peaks from the diffuse gamma background,
and because they can identify and differentiate between gamma-emitting radionuclides.
ii. Available spectrometric detectors generally fall into one of three main types: Ge
semiconductor detectors, NaI(Tl) scintillation detectors and LaBr3scintillation detectors.
iii. An NaI(Tl) detector with a diameter between 25 and 51 mm and a thickness in the same
range is adequate. Ge detectors with a diameter between 50 and 70 mm and a thickness
in the same range or smaller is recommended. These dimensions determine the
sensitivity of the detector.
iv. Other types of detectors with smaller crystal sizes such as cadmium zinc telluride (CZT) (a
semiconductor), and caesium iodide (CsI) (a scintillator) are appropriate for monitoring
the thyroid of very young children. CZT detectors have better energy resolution than
scintillators.
v. Shielding and collimation of the detector help to reduce measured background radiation
levels and so reduce detection limits and improve the reliability of the measurement.
They are not essential, but their use should be considered.
vi. Gamma cameras are available in medical imaging and nuclear medicine departments.
They may be useful for large scale screening of the population, although collimators
would need to be removed and pre-planning is required.
vii. Portable non-spectrometric instruments may be either gas-filled detectors (e.g. GM
tubes) or scintillation detectors. Examples are described in the text. Instruments should
comply with the requirements of the international standard IEC 60846-1:2014.
viii. Required sensitivity of non-spectrometric instruments for dose rate meters is such that
the lower limit of the dose rate range is 0.03 μSv·h-1, although instruments with a lower
limit of 0.1 μSv·h-1 are also adequate to detect levels below IAEA’s operational
intervention level for thyroid monitoring.
14
Calibration of spectroscopic devices
For spectroscopic devices used for in vivo monitoring, it is preferred to specify an energy-dependent
function describing counting efficiency, rather than a single calibration factor, as follows:
where:
N(E) is the net count in the full-energy peak of interest (i.e. background-subtracted) at energy
E,
tmeas is the measurement time in seconds,
yiis the yield of the gamma ray being measured (photons/nuclear disintegration), and
Ais the source activity of the iodine radio-isotope of interest (Bq).
The counting efficiency at a particular energy is the count rate of detected gamma rays divided by
the gamma ray emission rate.
The radioiodine activity in the thyroid is obtained with the same formula using the efficiency
determined from the calibration:
The count time for the calibration and the subject measurement do not need to be the same. If 133Ba
is used as a surrogate for 131I, then the yield of 133Ba should be applied for the efficiency
measurement, whereas the 131I yield must be applied for the subject measurement. The use of 133Ba
as an 131I substitute is explained below.
A calibration factor F(expressed in units of Bq per count/second) can be defined as the inverse of the
efficiency multiplied by the yield of (one of the) gamma rays of the radionuclide being measured
(equation x). The measured activity is the calibration factor times the measured quantity, i.e. the
count rate in the photoelectric peak. The calibration factor is thus defined for a particular
radionuclide gamma ray emission.
Calibration of non-spectroscopic devices
For instruments giving a count rate or a dose rate, the calibration factor for 131I measurements is
defined as follows:
F=A/M
where:
Ais the 131I source activity (Bq), and
Mis the background-subtracted instrument-specific measured quantity (Sv/h for example).
The background must be subtracted from both calibration phantom and subject measurement
readings. The subject background should be measured on another body part of the subject (e.g. the
thigh, forearm or shoulder) to ensure that the contributions of other incorporated radionuclides are
correctly subtracted.
For instruments giving integrated dose or integrated count over time, the calibration factor can be
determined as described above for a given measurement time. If calibration and measurements are
carried out for different counting times an appropriate time correction factor must be applied.
II.2.2 Characteristics of phantoms suitable for radio-iodine in thyroid measurements
Thyroid phantoms used for the calibration of thyroid measurements should comply with the
following requirements:
Ayt
EN
E
imeas
)(
)(
measmeasi t
EN
F
t
EN
Ey
A)()(
)(
1
15
(i) The shape should mimic the thyroid
Monte Carlo simulations have shown that a realistic shape is not of prime importance. It has been
shown by Monte Carlo calculations [Gómez-Ros et al. 2017] that the thyroid phantoms of SCK•CEN
and of IRSN (see descriptions below) give the same counting efficiency (differences range 15 - 20%)
for measurements at a measurement distance of 5 cm with spectrometers. Similarly, these phantoms
give counting efficiencies that are similar to those obtained using realistic voxel models (differences
range from -25% to 6%) for a measurement distance1of 10 cm. Since no comparison has been made
for phantoms simulating the thyroid with a single cylinder to represent both lobes, the use of bi-
lobed phantoms is recommended.
Recommendations for overlying tissue thickness and position of the lobes are given below.
(ii) Age-dependent thyroid volume should be fixed according to age
Since it has been shown that for gamma-ray spectrometry the counting efficiency is a linear function
of the thyroid volume, it is important that thyroid volumes are fixed for specified ages [Gómez-Ros et
al. 2017]. For that purpose, a reasonable choice is to follow the ICRP recommendation, as given in
Table II.2.1.
Table II.2.1. Recommended age-dependent thyroid volume (cm3)
1 year
5 years
10
years
15 years
Adult (male)
1.7
3.2
7.5
11.4
19.05
(iii) Overlying tissue thickness and position of the lobes should be fixed according to age
Since the counting efficiency varies with the inverse of the counting distance, the position of the
thyroid in the neck should be as realistic as possible. There is no agreed consensus for the distance
between the neck surface and the thyroid nor for the position of the thyroid lobes. However, these
parameters were fixed in the IRSN and SCK•CEN phantoms using information from a literature
review [Karachalias 2013, Beaumont et al. 2017].
The SCK•CEN age-dependent thyroid phantom [Karachalias 2013] consists of two cylindrical
holes inside a cylinder. The age-dependent thyroid volume follows the ICRP recommendation (Table
II.2.1) and the bi-cylindrical shape is similar to that used in an IAEA phantom [IAEA 1996]. The
hollow cylinders contain vials filled with a radio-iodine solution, and the vial diameters are selected
to fit as closely as possible to the cylinder diameter. An illustration of the phantom is provided in
Figure II.2.1 and typical dimensions are given in Table II.2.2.
The IRSN age-dependent thyroid phantoms are 3D-printed models based on a realistic model
[Ulanovsky 1997] consisting of ellipsoidal lobes cut by the trachea and includes the isthmus. All the
phantom design parameters can be found in [Gardumi et al. 2013]. To match exactly the volume
given in Table II.2.1, slight scaling of these parameters is needed [Beaumont et al. 2017]. An
illustration of the phantom is provided in Figure II.2.1 and typical dimensions are given in Table II.2.3.
(iv) The phantom should be made of tissue equivalent material
For 131I, gamma ray absorption is not a crucial parameter. Materials having the same attenuation
properties around 360 keV as muscle or adipose tissues, such as poly-methyl-methacrylate (PMMA),
are suitable.
Availability of phantoms
Both SCK•CEN and IRSN have age-dependent thyroid phantoms that are available for lending.
The electronic files required to produce the 3D–printed models of the IRSN phantom are also
available for lending.
1The head of voxel phantoms is in close proximity to the chest, especially for younger ages. Consequently it is
impossible to calculate the counting efficiency for measurements at contact of the thyroid.
16
The Radek2company sells age-dependent thyroid phantoms but their volumes do not exactly match
the recommendations presented here.
The RSD3company sells a realistic adult phantom whose volume is around 16 cm3.
Figure II.2.1. Illustrations and relevant dimensions of the SCK•CEN (top) and IRSN (bottom) age-
dependent thyroid phantoms.
Table II.2.2. Parameters (mm) describing the age-dependent SCK•CEN thyroid phantoms
1 year
5 years
10 years
15 years
Adult
Inter lobes distance (e) 20 24 26 30 34
Lobe (hole) radius (R) 6 7.5 8 9 11
Overlying tissue thickness (T) 8 10 12 14 15
Thyroid depth (D=R+T) 14 17.5 20 23 26
2http://www.radek.ru/en/company/
3Radiology Support Devices Inc, http://www.rsdphantoms.com/
e
D
T
17
Table II.2.3. Parameters (mm) describing the age-dependent IRSN thyroid phantoms
5 years
10 years
15 years
Adult
Inter lobes distance (e) 15 19 24 28
Overlying tissue thickness (T) 3.7 4.2 4.4 4.6
Thyroid depth (D) 13.5 14.6 16.3 18.7
Suitable radionuclides for calibration of thyroid measurements
(i) For spectroscopic measurements
Use of 131I is not necessary. The efficiency of spectroscopic instruments can be determined using the
full-energy peak of 133Ba (356 keV) instead of that of 131I (364.5 keV).
(ii) For non-spectroscopic measurements
Since non-spectroscopic instruments integrate over the count rate energy spectrum (which depends
on the radionuclide emissions and on tissue scattering), it is difficult to design a mock 131I source. It is
thus recommended to use 131I for calibration.
However, if 131I is not available (perhaps due to its short half-life) a mock source of 133Ba and 137Cs
covered with a silver filter with a thickness of 1 mm may be used.
The 133Ba:137Cs activity ratio must be 8.84:1. With a 1 mm silver filter, 1 Bq of the mock source (sum
of 137Cs and 133Ba activities) results in an emission spectrum similar to that of 1 Bq of 131I.
Such a source has been used in an intercomparison exercise [Isaksson et al. 2017]. Participants who
calibrated with 131I obtained very good results.
II.2.3 Neck to detector distances for calibration and subject measurements
General recommendations
1. The neck to detector distance used for calibration must be the same as for measurements of
people.
2. If age-specific calibration phantoms are available it is recommended to perform measurements as
close as possible to the neck. This results in a DL that is as low as possible. It should be noted that
measurements with the detector in contact with the neck are not necessarily possible for children
(see Figure II.2.2).
Figure II.2.2. For children, measurements in contact with the neck are not always possible with
standard instruments, such as the spectrometer with an entrance window of 8.5 cm diameter
shown here.
2 years
7 years
10 years
18
3. If age specific calibration phantoms are not available, the following procedures are recommended.
Spectroscopic instruments:
- Perform measurements with a neck to thyroid distance of at least 20 cm. In such a case,
the data presented in Appendix A show that the efficiency difference between the one
year child and the adult is 20% or less. However, for a particular detector design
significantly different from those studied, this distance may be too small. For such a
distance, the efficiency drops dramatically and the DL increases accordingly. Therefore, it
is also recommended to use a shielded detector to reduce contributions from radio-
iodine in other parts of the body.
- Perform measurements at contact and apply a correction factor as described below.
For non-spectroscopic instruments:
It is recommended that the adult calibration factor should be corrected as described below.
Variation of calibration factor with age
For both spectrometric and non-spectrometric instruments, the calibration factor varies with thyroid
volume, which itself depends on the age of the measured subject. As shown in Appendix A, for
spectroscopic instruments, the counting efficiency varies linearly with the thyroid volume.
Calibration factors for spectrometric and non-spectrometric measurements have been obtained from
measurements made at CIEMAT and IRSN and from [Ulanovsky et al. 1997, Khrutchinsky et al. 2012,
Drozdovitch et al. 2013, Karachalias 2013, Hunt 2014, Nyander Poulsen et al. 2014, Isaksson M and
del Risco Norrlid L 2015, Gómez-Ros et al. 2017]. Inspection of these data show that the minimum
multiplicative correction factor that should be applied to the adult calibration factor to obtain the
calibration factor for a 5 year-old child is:
- 0.4 for close measurements (0-5 cm) with a spectrometer,
- 0.7 for far measurements (10-15 cm) with a spectrometer,
- 0.3 for contact measurements with a variety of dose rate meters and count rate meters,
- 0.5 for a gamma camera without collimators,
- 0.8 for a gamma camera with collimators.
The sources cited above have been used to extract “universal” correction factors for use when
calibration factors for children are not available, for the following cases:
- Close measurements (0-5 cm) with all instruments including gamma cameras without
collimators;
- Far measurements (10-15 cm) with spectrometric instruments including gamma-cameras
with collimators.
Due to the scarcity of data about gamma cameras, such correction factors should be used with
caution.
These correction factors are provided as a function of age in Table II.2.4 and Figure II.2.3. A linear
relationship with volume may be observed. The references given above and in Appendix A provide
data that might be more suitable for a given detector and/or counting distance.
Table II.2.4. Multiplicative correction factor to be applied to the adult calibration factor as a
function of age
5 years
10 years
15 years
Adult
Far measurements (10
-
15 cm) with
spectrometer including gamma camera with
collimator
0.8 ± 0.08 0.86 ± 0.07 0.88 ± 0.08 1
Close measurements (0
-
5 cm)
with
all
devices, including gamma camera without
collimator
0.65 ± 0.2 0.7 ± 0.15 0.9 ± 0.1 1
19
Figure II.2.4. Multiplicative correction factor to be applied to the adult calibration factor as a
function of thyroid volume
II.2.4 Detection limit and minimum assessable dose
Detection limits for spectrometric instruments
The detection limit (DL) is the minimum activity that can be measured with a given confidence level.
It depends mainly on three parameters: the duration of measurement, the counting efficiency of the
instrument and, for spectrometric measurements, the number of counts in the regions adjacent to
the photoelectric peak. The ISO definition for the DL (ISO 2010b) for spectroscopic instruments is:
where:
DL is the detection limit [Bq]
t is the duration of measurement [s]
P is the number of channels within the peak
nmis the number of channels adjacent to the
peak for continuum subtraction (nmmust be
equal on left and right of the peak)
n0is the number of counts in the left and right
regions adjacent to the peak
k= 1.645 for a 5% probability of wrongly not
rejecting the hypothesis that activity is
present
=yi, as defined in Section II.2.1
u(is the standard uncertainty of 
Alternative definitions of the DL can be found in the IDEAS Guidelines [Castellani et al. 2013], ICRU
[ICRU 2003] and in the French AFNOR standard [AFNOR 2013].
The case where the background contains a full-energy peak at the energy of interest, which is quite
likely if emergency measurements are carried out near the evacuation zone, is not dealt with in (ISO
2
*
*
2
2
0
2
0
*
)(
1
22
2
1
u
k
n
n
P
n
n
P
k
t
k
DL
mm
20
2010b). In this case, when an interfering peak occurs in the background, the DL equation should be
adapted in line with ISO 2010b as follows:
where
nIis the net area of the interfering peak,
tBis the counting time of the background, and
ݏ
is the variance characterising the uncertainty of the estimation of nI.
When the measurement times of the subject and of the background are the same, the numerator of
the above formula is the same as the one given in ICRU [ICRU 2003].
Detection limits for non-spectrometric instruments
For non-spectrometric instruments, it is recommended to calculate the DL as follows [Oliveira et al.
2013, Heath Physics Society 2011]:
where
Bis the standard deviation of the background measurement (counts/min or Sv/h), and
Fis the calibration factor of the instruments as defined in Section II.2.1.
Application of this relationship requires the same measurement time for the background and the
monitored subjects. This formula corresponds to a risk of false positive and false negative errors of
5%.
Detection limit and minimum assessable dose
The DL corresponds to a minimum assessable dose in terms of either committed effective dose or
absorbed dose to the thyroid over 30 days. From the tables given in Section III it is possible to
determine the DL (for 131I measurement in thyroid) which corresponds to 1 mSv committed effective
dose following inhalation of 131I only. This DL is given as a function of age and measurement time
after intake (Table II.2.5).
This table has several uses:
1. If the DL cannot be improved then the ratio of the current DL over the one given in the table gives
the minimum committed effective dose that can be assessed. For example, if the DL is 20 kBq then
for an adult measurement at 2 days after intake, one can assess a minimum dose of (20/11.2)*1
mSv=1.8 mSv.
2. Provided that the DL can be improved, a DL can be determined that corresponds to a given
minimum assessable dose. For example, to assess 5 mSv from a measurement of a 1 year child at 7
days, a DL of 5*0.7=3.5 kBq is thus needed.
3. Table II.2.5 can also be used to determine a DL that corresponds to a given minimum assessable
thyroid absorbed dose. With a tissue weighting factor of 0.05 for the thyroid, the committed
effective dose is approximately 0.05 times the absorbed dose to thyroid (integrated over 30 days).
As an example, the DL required to be able to assess the absorbed dose to thyroid of 50 mGy
(integrated over 30 days) for a measurement at 3 days after intake for a 15 year old child
corresponds to 50*0.05=2.5 mSv committed effective dose. A DL of 2.5*6.7=17 kBq is required to
meet this requirement.
Table II.2.5 applies only if stable iodine has not been taken before or after intake. In particular, if
stable iodine has been taken, it cannot be assumed that the committed effective dose is 0.05 times
B
FDL
65.4
2
*
*
2
2
2
0
2
0
*
)(
1
22
2
1
u
k
s
t
t
n
t
t
n
n
P
n
n
P
k
t
k
DL
I
B
I
Bmm
21
the thyroid dose. If stable iodine has been taken, Section III and [Vrba et al. 2017] provide data that
can be used to calculate a table similar to Table II.2.5 for thyroid absorbed dose.
For simplicity, the case of 131I only has been addressed here. In practice, if other radionuclides
are contributing to the dose, the DLs given here will correspond to higher committed effective doses
and higher thyroid absorbed doses.
In practice, the possibility of improving the DL for a given instrument is quite limited. For
spectrometric instruments and dose rate meters, the background can be reduced by choosing a
measurement location where the background is as low as possible. Shielding and collimating the
instruments reduces the background; this is possible for spectrometers but more difficult for hand-
held instruments such as dose rate-meters.
For spectrometric instruments, the measurement time can be increased but practical considerations
such as the comfort of the measured subject and the number of subjects to be measured are limiting
factors.
Table II.2.5. Detection limits (kBq) corresponding to a committed effective dose of 1 mSv following
inhalation of 131I. The detection limit is for a measurement of 131I activity in the thyroid.
Measurement
Time
After Intake
Reference age group
Infant 1 year 5 years 10 years 15 years Adult
6h 0.7 0.8 1.3 2.6 4.0 6.3
12h 1.1 1.1 2.0 4.0 6.3 10.0
24h 1.3 1.4 2.4 4.8 7.1 11.6
2 days 1.2 1.3 2.3 4.8 7.1 11.2
3 days 1.1 1.1 2.0 4.2 6.7 10.3
4 days 0.9 1.0 1.9 3.8 5.9 9.1
5 days 0.8 0.9 1.6 3.4 5.3 8.3
7 days 0.6 0.7 1.3 2.9 4.5 7.1
10 days 0.4 0.5 0.9 2.2 3.3 5.3
15 days 0.2 0.3 0.6 1.3 2.1 3.3
20 days 0.1 0.1 0.3 0.8 1.3 2.1
30 days 0.03 0.04 0.1 0.3 0.5 0.8
60 days 0.0006 0.0012 0.0042 0.0185 0.0303 0.1
22
Section II.2. Calibration and detection limits
Recommendations
i. For spectrometric instruments, it is recommended to use the energy-dependent counting
efficiency rather than a calibration factor to determine thyroid activity from the
measurement result. For non-spectrometric instruments the use of a calibration factor is
preferred.
ii. The background must be subtracted from both calibration phantom and subject
measurement readings. For non-spectrometric instruments the subject background
should be measured on another body part of the subject (e.g. the thigh, forearm or
shoulder) to ensure that the contributions of other incorporated radionuclides are
correctly subtracted.
iii. Detectors should be calibrated with thyroid phantoms and the calibrations should be
traceable. It is recommended to use age-specific bi-lobed thyroid phantoms with
volumes as recommended by ICRP (Table II.2.1). The thickness of the overlying tissue of
the phantom should if possible be selected according to the age of the subject. Examples
are given in Tables II.2.2 and II.2.3.
iv. Spectrometric instruments may be calibrated with either 131I or 133Ba sources. It is
recommended to calibrate non-spectrometric instruments with 131I sources. If this is not
possible then a mock source, as described in Section II.2.1, should be used.
v. Neck to detector distances must be the same for calibration measurements and subject
measurements.
vi. If the detector has been calibrated for different ages then it is recommended to perform
measurements at ‘close contact’, with the detector positioned in front of the thyroid and
as close as possible to the neck but without touching the skin. The thyroid is positioned
below the Adam’s apple and above the clavicles.
vii. For young children, it is recommended to use detectors of smaller sizes so that
measurements at ‘close contact’ are possible.
viii. If the detector has only been calibrated for the adult then it is recommended:
to perform the measurement at close contact and use the correction factors
given in Table II.2.4, or
to perform measurement at distances of at least 20 cm and apply the adult
calibration, provided the detection limit of the measurement is adequate.
ix. For spectrometric and non-spectrometric instruments, it is recommended to calculate
detection limits as given in Section II.2.4. For both types of instrument, the background
peaks or other interfering peaks must be taken into account.
ix. The minimum assessable dose depends on the detection limit and the time of
measurement. To determine whether the measurement procedure is adequate, the
minimum assessable dose should be calculated using the data in Table II.2.5. This enables
a quick evaluation of the minimum assessable dose in terms of the committed effective
dose or the absorbed dose to the thyroid. However, this table is not applicable if stable
iodine has been administered.
23
II.3 Measurement preparation and practice
This section specifies requirements for the location and the equipment needed to carry out
monitoring of people. The fulfilment of all of these requirements represents an ideal situation and it
must be recognised that, depending on the accident circumstances, it may not be possible to meet all
of these requirements.
Planning is required to fulfil these requirements, for example:
-to identify potential monitoring locations,
-to decide who is responsible for monitoring, decontamination, providing radiation
protection advice and counselling, and
-to make sure the appropriate equipment is available including materials for
decontamination and replacement clothing.
Essential items are given below, further details can be found in [Monteiro Gil et al. 2017] and in
[Etherington et al. 2017].
II.3.1 Location of monitoring and required equipment
The section gives requirements for the location and equipment needed to carry out monitoring of
people.
To fulfil these requirements, planning is required for example to identify potential monitoring
locations, and to purchase and store materials for decontamination and replacement clothing.
Location of monitoring facilities
Places used for monitoring should be close to the affected area but must not be located in areas with
significant environmental contamination. For IAEA threat categories I and II, they should be outside
the urgent protective action planning zone (UPZ) boundary [IAEA, 2003].
Monitoring facilities should be located at, or adjacent to, any evacuee reception centre (an evacuee
reception centre is a location for receiving evacuees that provides temporary accommodation).
For nuclear sites where the operator has an emergency plan, locations suitable for monitoring should
be identified during the planning stage. It may be necessary to identify several possible locations as
an accident may make some locations unsuitable.
When deciding on potential locations for monitoring consideration should be given to the transport
of people.
Types of premises which could be used for monitoring
Buildings or establishments which might be suitable for monitoring of people include:
Sports centres
Schools
Warehouses
Community halls
Dedicated temporary structures (tents).
Hospitals and medical centres should be avoided as medical treatment takes priority over radiation
monitoring, whether or not it is associated with the radiation emergency.
The suitability of all prospective locations for monitoring should be confirmed in advance.
Requirements of premises used for monitoring
The following is a list of attributes which are required for premises used for monitoring. Should a
location not meet all of these requirements, consideration should be given as to how the function
can otherwise be carried out.
Be available within a few hours of any identified requirement for monitoring
Have an area for people awaiting monitoring (either indoors or outdoors under shelter)
Have sufficient indoor space for monitoring to deal with the expected demand
24
Have adequate and definable access routes which can be controlled with separate entrance
and exit (exit may lead into an evacuee reception centre)
Have an area for recording and reporting information with communications equipment
Have a private area for counselling concerned members of the public
The following facilities are essential:
Adequate toilet facilities for staff and the general public. Ideally there should be separate
toilets for pre- and post-monitoring areas.
Environmental control (against excessive heat or cold)
Mains electrical power
Depending on the incident, the following may also be required:
Facilities to remove external contamination from people and to provide replacement
clothing
An area to store contaminated clothing and other contaminated items
A staff rest area
Instructions for preparing the area to be used for monitoring
Clear unnecessary furniture from the area as far as reasonably practicable
Section-off areas for monitoring and other areas, using partition screens or barriers
Consider setting up a queuing system for people waiting for monitoring
If possible, cover heavily used floor areas with a non-slip material (this is only a requirement
if external contamination is expected)
Establish a one-way system to prevent mixing of potentially externally contaminated people
with uncontaminated people
Equipment required
Equipment for controlling movement of people:
Direction signs
‘No entry’ signs
Barriers
Information boards
Equipment to prevent the spread of contamination:
Disposable mats with an adhesive surface
Polythene bags
Temporary covering materials (plastic/paper sheeting) and tape
Replacement disposable clothing (so that people can change into uncontaminated clothes)
Equipment for monitoring:
Monitoring instruments
Spare batteries (if needed)
Report and registration forms (see Section II.5)
II.3.2 Maintenance of monitoring devices
Monitoring instruments must be maintained and periodically checked so that they are ready to be
used in case of emergency.
Spectrometric instruments to be used for monitoring of radioiodine in the thyroid should be properly
calibrated, tested and validated according to quality criteria such as those described in the ISO 28218
standard [ISO 2010a].
Dose rate meters or count rate meters should be properly calibrated and validated according to the
IEC 60846 standard [IEC2009].
25
Whatever the instrument, its performance should be checked periodically using reference traceable
radioactivity sources. Periodic validation of the instrument could be done either by:
measurement of a different source to the one used for calibration, to confirm stability of the
response of the instrument, or through
participation in an intercomparison exercise to confirm response of the instrument for
measurements of iodine in the thyroid.
For both kinds of instruments the acceptance criteria for relative bias defined in ISO 28218 are
recommended.
II.3.3 External contamination monitoring
Detailed recommendations for external contamination monitoring are outside the scope of this
document, so only a brief overview is given here. Additional information can be found in [IAEA 2017,
Thompson et al. 2011, Rojas-Palma et al. 2009].
Internal contamination monitoring should be carried out only after external contamination
measurements have been performed and adequate decontamination actions carried out. If external
contamination has not been ruled out prior to internal contamination monitoring, false positive
measurements results might be found.
All body parts should be monitored for external contamination, particularly the hands, the face and
the hair. In the event of positive measurements, decontamination by showering should be performed
and replacement clothes provided. If a second external contamination monitoring is positive, internal
contamination may be suspected.
Ambient dose rate monitors as described in II.1.2 can be used to monitor external contamination. In
[Rojas-Palma et al. 2009] it is recommended to carry out at most two decontamination cycles. In
[IAEA 2017] it is recommended to carry out decontamination if skin monitoring (at 10 cm from the
bare hands) results in a dose rate higher than 1 Sv/h, after background subtraction.
II.3.4 Protection of instruments against contamination
Monitoring equipment can be contaminated by airborne radionuclides and by the transfer of
radionuclides from the monitored subjects, even if efforts to carry out decontamination are rigorous
[Kurihara et al. 2012].
It is advised to cover all instruments (including the chair used for spectrometric measurements) with
a removable thin plastic film. For example, plastic bags can be used, and replaced before each new
measurement or if contamination is suspected. For measurements made outside with hand-held
instruments, plastic bags offer a protection against deposition of airborne radionuclides.
When measurements are carried out in a dedicated room, it is recommended to provide the
monitored subjects with replacement disposable clothing, including shoes.
II.3.5 Background characterisation
On-site measurements of radio-iodine in the thyroid of exposed persons are likely to be affected by
the radio-iodine present in the environment background. The contribution of the background to the
subject measurement should be characterised and subtracted. Measurement of the thyroid of a non-
contaminated person (e.g. dosimetry staff) or a blank phantom is recommended for this purpose. In
the case of 131I detected in an individual using spectrometry instruments, the count rate associated
with the peak at 364 keV in the background measurement should be subtracted from the count rate
of the 364 keV peak in the spectrum of the exposed person, and this net value should be used for the
calculation of the activity of 131I in the thyroid. For a long monitoring campaign, it is recommended to
measure the background at least three times per day since it can be affected by weather conditions.
A more efficient way is to use an ambient dose rate monitor at the measurement site and to re-
measure the background if the ambient dose rate varies. For example, a variation of 50% should
trigger a re-evaluation of the background.
For non-spectrometric instruments the background can be measured:
26
-on an uncontaminated part of the body, usually the thigh, forearm or shoulder
-if this is not possible then the ambient dose rate measured away from people can be
used.
Thyroid monitoring should be carried out in locations with low background, as close as possible to
the emergency area.
II.3.6 Measurement duration and measurement time
Measurement duration
For spectrometric instruments, the measurement duration is a variable in the DL formula (Section
II.2.4) and thus has a direct impact on the DL. For a given background and efficiency, a longer
measurement duration decreases the DL. The corresponding minimum assessable dose therefore
also decreases with the measurement duration.
Because measurement durations for people cannot be very long, the main parameters to consider
for the optimum measurement duration are as follows:
The minimum committed effective dose or thyroid dose to be assessed. They depend on the
age and on the time between the intake and the measurement. The tables given in Section III
and Table II.2.5 guide this assessment.
The background, as defined for the calculation of the DL
The number of people to be monitored and the number of available measurement systems.
Higher DLs may be accepted if it is important to measure rapidly a large number of people.
For dose-rate meters and count-rate meters the only requirement for measurement duration is that
a stable instrument reading can be taken. For improved accuracy, replicate measurements may be
carried out.
Measurement time (time after intake)
The biological half-time of iodine in the thyroid is 80 days for an adult and 15 days for a 1 year old
child. However, 131I has a short radioactive half-life of 8 days and so 131I may not be measurable
weeks or months after an intake, depending on the intake activity and the DL of the instrument. The
minimum assessable dose provides a good criterion to assess the maximum period after intake
during which thyroid measurements can be carried out (Table II.2.5).
It is shown in Appendix A that thyroid measurements can be affected by gamma rays emitted by
radioactive iodine present in other body organs, particularly if measurements are carried out within
the first 24 hours after intake. It is thus recommended that the earliest measurement time for
starting the measurements is 1 day after the intake. Moreover, it is shown in Section III that the dose
conversion coefficient does not critically depend on the time of intake if measurements are carried
out between 1 day and 4 days after intake. However, if subjects present themselves for
measurements earlier than 1 day after intake, then they should be measured. In addition, for first
responders, a precise measurement will not be the highest priority and a rough estimation before 1
day should be enough to determine whether protective actions have been effective.
For children less than 5 years, it cannot be excluded that for some spectrometers the contribution
from other organs is still about 20% after 24h (Gómez-Ros et al. 2017). It is thus recommended either
to wait for 48 hours to carry out the measurement, or to repeat early measurement to confirm the
results.
As shown in Table II.2.5, measurements carried out 20 days after intake would require DLs that are
very difficult to obtain if committed effective doses around 1 mSv are to be assessed.
In conclusion, it is recommended to perform measurements of 131I between 24h and 20 days after
intake. It is also recommended to select a representative sample of the population (both workers
and members of the public) and monitor them as soon as possible with germanium detectors, in
order to identify short-lived radionuclides. The dose contribution of these radionuclides could be
taken into account for subjects measured later. Any other indirect means that can help in assessing
the intake pattern of short lived radionuclides, such as the use of carbon iodine filters, or
environmental sample measurements, or calculations of air concentrations, should be considered.
If stable iodine has been taken, thyroid monitoring may be performed:
27
-Between 0 and 72h after the intake. In this case positive measurements should be interpreted
using a special dosimetric model that takes into account iodine prophylaxis (Section III).
-72h after intake. In this case positive measurements should be interpreted using the dose
conversion coefficients provided in Section III.
II.3.7 Measurements of very young children
For measurements of young children under 5 years old, three issues are of special concern:
- the behaviour of the child during the measurement;
- the availability of reliable calibration factors;
- the selection of an appropriate monitoring instrument and counting distance.
To ensure that the child keeps the correct position during spectrometric measurements, it is
recommended that parents stay with the child. For non-spectrometric measurements, the counting
time is low and thus this issue should be of minor concern.
To obtain reliable calibration factors, three methods are possible:
- The use of phantoms for small thyroid volumes (around 2 cm3) to determine the energy-
dependent counting efficiency. As far as is known, only SCK•CEN has developed such
phantoms for children under 5 years old [Karachalias 2013].
- Estimate the calibration factor by a linear extrapolation of calibration data for other age
categories.
- Use correction factors calculated from Figure II.2.4.
As illustrated by Figure II.2.2, typical spectrometric instruments are too large to be placed in contact
with the neck of a very young child. Non-spectrometric instruments generally have a smaller
entrance window and can thus be placed in contact.
When using a spectrometric monitoring instrument one can:
- Use a counting distance of around 10 cm, taking care that during measurements the neck
remains outstretched. In this case, a conic collimator is recommended to reduce the
contributions from other organs or from the parents.
- Use a spectrometric instrument with a small entrance window. These can be obtained from
different manufacturers. For example CZT or CsI spectrometers with an entrance window of
respectively 2.5x2.5 cm and 3.5x3.5 cm are available from well-established manufacturers.
Small NaI(Tl) spectrometers are also available with a 4.5 cm diameter entrance window. Such
instruments can be placed in contact with the neck, compensating for their lower counting
efficiency compared to typical NaI(Tl) detectors with larger crystal diameters.
Table II.3.1. Breathing rate (m3/day) as a function of age
3 months
1 year
5 years
10 years
15 years
Adult
2.86
5.16
8.72
15.3
20.1
22.2
If the measurement of a very young child is not possible, an alternative method is to calculate the
dose using a surrogate person. For that purpose, a person who stayed with the child at the time of
intake should be identified (a parent, child-minder or teacher) and the intake deduced from the
measurement of the surrogate person. Then, taking into account the breathing volume ratio
between adult and children [ICRP 1995], as given in Table II.3.1, the child’s intake can be deduced
and hence the dose.
Finally, if possible, the results obtained from a direct measurement and the measurements of a
surrogate person should be compared.
28
Section II.3. Measurement preparation and practice
Recommendations
i. Planning and preparation for monitoring of people should be carried out:
to identify potential monitoring locations,
to decide who is responsible for monitoring, decontamination, providing
radiation protection advice and counselling, and
to make sure the appropriate equipment is available.
ii. Places used for monitoring should be close to the affected area but must not be located
in areas with significant environmental contamination. They should be located at,
adjacent to, or near to, any evacuee reception centre which receives and provides
temporary accommodation for evacuees.
iii. The type and requirements of premises that might be suitable for monitoring are
described in Section II.3.1. The equipment needed is also described.
iv. Monitoring instruments should be properly calibrated, tested and validated according to
quality criteria [ISO 2010a]. They must be maintained and periodically checked so that
they are ready to be used in the event of an emergency.
v. Internal contamination monitoring should be carried out only after external
contamination measurements have been performed and adequate decontamination
actions carried out.
vi. All instruments (including any chair used for spectrometric measurements on people)
should be protected against contamination by covering with a removable thin plastic
film. For monitoring instruments, plastic bags or a thin plastic film can be used, and
replaced before each new measurement, if contamination is suspected.
vii. The contribution of the background to the subject thyroid measurement should be
characterised and subtracted. For spectrometric instruments, a background
measurement can be performed by measuring the thyroid of a non-contaminated person
(e.g. dosimetry staff) or a blank phantom. For non-spectrometric instruments, a
background measurement on an uncontaminated part of the body, usually the thigh,
forearm or shoulder, is recommended.
viii. Increasing the measurement time for spectrometric instruments decreases the detection
limit (DL) and the corresponding minimum assessable dose (Section II.2.4).
Measurement duration should not be no longer than that required to achieve the
required DL. For dose-rate and count-rate meters, the only requirement for
measurement duration is that a stable instrument reading can be taken.
29
Section II.3. Measurement preparation and practice
Recommendations (continued)
ix. Measurements of 131I should ideally be performed between 24 h and 20 days after
intake; later measurements may not have adequate sensitivity. If subjects present
themselves for measurements earlier than 24 h after intake, then they should be
measured. It is also recommended to select a representative sample of the population
(both workers and members of the public) and monitor them as soon as possible with
germanium detectors, in order to identify short-lived radionuclides. The dose
contribution of these radionuclides could be taken into account for subjects measured
later.
Measurements of children under 5 years old
x. For measurements of children under 5 years old, reliable calibration factors should be
obtained by:
using phantoms with small thyroid volumes (around 2 cm3),
estimating the calibration factor by a linear extrapolation of calibration data for
other age categories, or
using correction factors calculated from Figure II.2.4
xi. For thyroid measurements of very young children with spectrometric instruments, it is
recommended that parents stay with the child to ensure that the child is content and
keeps the correct position. For non-spectrometric measurements, the counting time is
low and thus this issue may be of minor concern.
xii. Spectrometric instruments with small entrance windows are suitable for measurements
of children under 5 years old, positioned at close contact to the neck. Examples include
CZT or CsI spectrometers with an entrance windows of < 4cm in diameter and small
NaI(Tl) spectrometers with window diameters of about 4.5 cm. Non-spectrometric
instruments generally have smaller entrance windows and can thus be placed in close
contact.
xiii. Spectrometric instruments with larger entrance windows can be used for very young
children (< 5 y old) with neck-to-detector distances of 10 to 15 cm. In this case, a conic
collimator is recommended to reduce the contributions from other organs or from the
parents.
xiv. If the measurement of a very young child is not possible, then a dose should be
calculated from a measurement of a surrogate person who stayed with the child at the
time of intake. The child’s intake can be inferred from the surrogate person’s intake by
taking into account the breathing volume ratio between adult and child.
30
II.4 Measurement uncertainties and measurement bias
It is important that those responsible for thyroid monitoring are aware of the general level of
uncertainty and bias associated with thyroid measurements. This section presents indications of the
levels of uncertainty and bias in the assessed radio-iodine content of the thyroid associated with the
major contributing sources. The topic is discussed in greater detail in [Vrba et al., 2017].
II.4.1 Uncertainties due to counting statistics
Uncertainties due to counting statistics are relatively small when the measured activity is well in
excess of the DL. For measured activities close to the DL, uncertainties will be around ±30%.
II.4.2 Uncertainties due to detector positioning
Uncertainties due to incorrect positioning of the detector relative to the calibration position
decrease with increasing distance. For a neck to detector distance of 10 cm, a 5 mm error (due either
to a setup error or movement of the person during the measurement) may result in uncertainties up
to ±10%.
II.4.3 Bias due to radio-iodine activity in organs other than the thyroid
When thyroid measurements on children are made six hours after the intake using uncollimated
detectors at a distance of 10 cm, more than 50% of the measured counts arise from this extra-
thyroidal contribution. For adults, the corresponding figure is about 30%. After one day, the extra-
thyroidal contribution is about 20% and 6% for children and adults, respectively, falling to 8% and 2%
after two days.
II.4.4 Bias due to the age of the measured person
The use of counting efficiencies or calibration factors determined for a different age than that of the
person to be measured introduces a bias which ideally should be corrected if correction factors are
available. These correction factors depend on age and distance [Gómez-Ros et al. 2017]. The
counting efficiency decreases with thyroid volume and the reduction is more significant at close
distances. Using adult male calibration factors for measurements of children up to ten years old
results in overestimates in the activity in the child’s thyroid by about 50% at 5 cm distance and about
30% at 17.5 cm. Using the same correction factors for all children up to ten years of age results in an
uncertainty of about ± 10% relative to results obtained using the correction factor for the correct age
group.
When the correct calibration factor for the age and sex of the person measured is used, there remain
uncertainties due to inter-subject variability in thyroid mass as detailed below.
II.4.5 Uncertainties associated with the calibration phantom
Counting efficiency and calibration factors depend on the calibration phantom used (Section II.2).
Calibration factors determined from measurements on two physical phantoms (SCK-CEN and IRSN)
and a voxel phantom for the different age groups and the four detectors used [Gómez-Ros et al.
2017] differed by about 10% for neck-to-detector distances of 10 cm or more, but were larger, about
20-30%, at closer distances (< 5 cm).
31
II.4.6 Uncertainties due to variability in thyroid mass
The variability in mass indicates, for males and females, an uncertainty in mass of about 50% for the
foetus and new-born, about 30% for 1 to 10 year old children, and about 20% for adults.
As a result, the uncertainty in the efficiency is of the order of 5% for children under 10 years old and
around 10% for older subjects.
II.5 Results management
In the event of a radiation emergency, the results of people monitoring should be managed in
accordance with the EU procedures that are in force, tailored to the specific national situation and
location and taking into account the requirements of the responders of the radiation incident. It is
important that all personal data should be collected and recorded in accordance with data protection
and confidentiality procedures.
The following recommendations are based on [Thompson et al. 2011,Rojas-Palma et al. 2009,ISO
2011, ISO 2006]
II.5.1 Registration
Before measurement all persons must be registered, receiving a unique registration code in order
that their identification is clear and unequivocal. The unique code should be used in all reporting
forms linking the measurement results with the monitored person.
The personal and contact information (date of birth, address, phone number) of the measured
person should be collected in a database for reporting reasons and to facilitate future additional
monitoring that may be required by a long-term follow-up programme. The location of the person
when the radionuclide release occurred and the subsequent locations before monitoring should also
be recorded.
II.5.2 Collecting measurement results
The following measurements should be carried out:
- screening for external contamination,
- thyroid internal contamination monitoring,
- whole body internal contamination monitoring if high energy gamma-ray emitting radionuclides
have been released, and
- urine monitoring if alpha- and beta-emitting radionuclides have been released without the
presence of high energy gamma-ray emitting radionuclides.
Section II.4. Measurement uncertainties and measurement bias
Recommendations
This section details the sources of uncertainties affecting the measurement and order of
magnitude estimates are provided.
Even for emergency monitoring, it is recommended to establish an uncertainty budget associated
with the measurements made, so that information can be provided on the general level of
uncertainty and bias in the results of iodine in thyroid measurements.
32
The results of external and internal contamination measurements should be compared with action
levels without delay to determine the need for follow-up actions [Etherington et al. 2017].
II.5.3 Records
All the measurement results should be unequivocally linked to the monitored subject for the
purposes of communication of results, further decisions and dose estimation.
After each decontamination procedure, the results of screening for external contamination should be
recorded on an appropriate external contamination survey report.
Similarly, the results of the thyroid contamination monitoring or whole body monitoring must be
recorded on an appropriate survey report.
The reports of the results should include:
- the unique code of the measured person
- the type of the measurement: external contamination, thyroid monitoring, whole body
monitoring
- date and time of exposure, as far as possible
- date and time of measurement
- whether stable iodine was taken, and if so, date and time of administration
- a detailed description of the measurement conditions (geometry, counting time, equipment
type, model, serial/number, background counts, and calibration factor)
- the identified radionuclides, in the case of spectrometric measurements
- the monitoring results in terms of measured activity [Bq]
- if the presence of activity was not confirmed, then the results should indicate “below detection
limit (DL)” and the DL should be given
- The monitoring results, in terms of committed effective dose or absorbed dose to a named
organ. If assessed doses cannot be directly obtained after measurements, they should be
appended to the report once available
- action levels
- name of the monitoring person responsible
- monitoring entity
The preparation of report templates and development of software to generate these reports is an
important aspect of emergency preparedness.
II.5.4 Reporting
Accurate information regarding the monitoring results should be provided to all the people who have
been measured and to the responders of the radiation incident. Data protection and confidentiality
procedures should be followed. People who are monitored should receive a report of their own
results. The reporting form should contain, as a minimum, their unique code, personal information,
the entity that performed the measurement, the description of the actions carried out (external
contamination monitoring, decontamination, internal contamination monitoring) and the
measurement results.
Simple, easy-to-understand information should also be provided to explain the meaning of the
results in terms of risk to health [Etherington et al. 2017]. In cases where the monitoring team is not
taking the lead in explaining the results of measurements to the people monitored, it should be
clearly indicated who is responsible and what the next steps are following the monitoring.
According to the general organisation of the emergency protocol, the responders should receive, at
the frequency agreed with the monitoring unit, the following information:
- the number of people monitored,
- number of people without detectable contamination,
- number of people directed to medical assessment,
- number of people with only external contamination, and
- ranges of doses for people measured with detectable internal contamination.
33
Such information, which maybe be considered for public release, should be anonymised because the
measurement results and assessed doses are considered as private data and are protected.
Section II.5. Results management
Recommendations
i. Before measurement, all persons must be registered, receiving a unique registration
code in order that their identification is clear and unequivocal. The unique code should
be used in all reporting forms linking the measurement results with the monitored
person.
ii. Personal and contact information of the measured person should be collected in a
database in accordance with data protection and confidentiality procedures. The
location of the person when the radionuclide release occurred and the subsequent
locations before monitoring should also be recorded.
iii. The types of measurements that should be performed include:
screening for external contamination,
thyroid internal contamination monitoring for radio-iodine,
whole body internal contamination monitoring if high energy gamma-ray
emitting radionuclides have been released, and
urine monitoring if alpha- and beta-emitting radionuclides have been released
without the presence of high energy gamma-ray emitting radionuclides.
iv. All measurement results should be recorded on survey reports and linked to the
monitored subject via the unique registration code. The information that should be
recorded is listed in Section II.4.3. Templates for these reports should be prepared in
advance.
v. Accurate information regarding the monitoring results should be provided to all
people who have been measured. People who are monitored should receive a report
of their own results. The reporting form should contain, as a minimum, their unique
code, personal information, the description of the actions carried out (external
contamination monitoring, decontamination, internal contamination monitoring),
the measurement results and the entity that performed the measurement.
vi. Simple, easy-to-understand information should also be provided to explain the
meaning of the results in terms of risk to health. Teams of appropriate people
should be present to provide reassurance to all those who have been monitored, to
answer questions, and to explain the procedures of any follow-up programme.
vii. The responders should receive, at the frequency agreed with the monitoring unit, the
following information:
number of people monitored,
number of people without detectable contamination,
number of people directed to medical assessment,
number of people with only external contamination, and
ranges of doses for people measured with detectable internal contamination.
Such information should be anonymised.
34
II.6 Thyroid measurements made by members of the public
Purpose and target group of Section II.6
This section is intended for radiation protection experts and decision makers who intend to support
members of the public in performing their own measurements.
These recommendations can be used to set up a training or education programme and to prepare
information leaflets intended for the public. They may also be useful when recommending reliable
measurement instruments to citizens or groups of citizens. Education programmes should be
designed in collaboration with citizens involved in preparedness for radiation emergencies.
While the authors believe that, with proper training, members of the public can perform reliable
measurements of thyroid activity, it is considered that evaluation of doses and associated risks to
health from those measurements remain a specialist topic that should be performed only by trained
experts.
Characteristics of measurements made by members of the public
As was found after the Fukushima Daichi nuclear power plant (NPP) accident, it is highly probable
that citizens will carry out their own measurements and communicate their results through various
means including social networks [Monteiro Gil et al. 2017]. Citizens’ measurements are likely to be
carried out:
- for their own benefit,
- with various instruments,
- with no (or limited) quality assurance, such that the reliability of measurements
cannot be confirmed,
- with limited technical support,
- on a number of individuals that cannot be predicted in advance or controlled,
- in many locations, including areas in which people have low levels of contamination
where the need for monitoring is low.
If citizens are not adequately trained or informed, misinterpretation of results cannot be excluded.
Nevertheless, measurements made by members of public can be an important aspect of the
management of population concerns during a NPP emergency exposure situation. The advantages of
such measurements include:
- additional measurement data; in particular, data can be obtained for areas not
covered by measurements made by a radiation monitoring service.
- Reassurance, because data obtained by "one's own measurements" are often trusted
by people
Simple and comprehensible instructions on how to carry out such measurements would need to be
delivered to the public by established communication means, preferably supplemented by training
given by professionals.
35
Section II.6. Thyroid measurements made by members of public
Recommendations
The following recommendations are derived from [Lebacq et al. 2017, Monteiro Gil et al. 2017].
i. How to identify a suitable instrument for measurement of dose rate over the thyroid
Gamma dose-rate meters are preferred to count-rate meters for the reasons given below.
Instruments dedicated solely to alpha-beta contamination measurement may cause errors in
measurement data interpretation.
A calibration factor for the conversion of the instrument readout to the 131I activity in
thyroid (e.g. μSv·h-1 per kBq or cps per kBq) should be established unless dose/count rate results
are only to be used for comparison with reference level values (generally expressed as ambient
dose equivalent, H*(10)) set by national authorities according to the IAEA concept of Operational
Intervention Levels [IAEA 2017].
The calibration factor must be obtained with the support of professionals, who have the means
to carry out calibration measurements with thyroid phantoms and metrological traceable
sources.
For dose-rate meters, the minimum measurable dose rate is 0.1 μSv·h-1.
Preferred instrument dimensions: an effective area of the detector 15 cm² (or 5 cm in
length for cylindrical instruments, typically small size Geiger-Muller tubes) is recommended.
Instruments should have technical support from the manufacturer, be well-documented,
and have a simple instruction manual. Compliance with IEC 60846-1:2009 is recommended.
A reference point for the instrument or a proper instrument orientation should be
marked on the instrument case.
The instrument should allow the operator to make readings when positioned in contact
with the neck.
Instruments with digital output are preferred, as they are generally easier to read than
those with analogue outputs.
Instruments with few switches and adjustable parameters are preferable as they are
easier to use and less likely to be set up incorrectly.
Malfunction warning and low battery warning should be included among the instrument
functions.
Advanced functions of data storage and logging may be useful if an established network
of measurement data exchange is available.
ii. How to perform simple function checks
Read the instruction manual for the instrument.
Allow the instrument to stabilise after switching on.
Check instrument functions and settings as described in the instruction manual.
Check instrument response to different dose rate levels to see readout change. For example,
carry out dose rate measurements inside and outside a building.
36
Section II.6. Thyroid measurements made by members of public
Recommendations (continued)
iii. How to make simple measurements
Allow the instrument to stabilise after switching on, and then perform function checks.
A reading should only be recorded after the instrument reading has stabilised. If the
reading is increasing then the user should wait until it starts to decrease, that is, it is fluctuating
around a median value. It is the median value that should be recorded. The converse is also true;
if the reading is decreasing then the user should wait until it starts to increase.
When measuring a person, ensure at least a 3 m separation between the measured
person and potentially externally contaminated people, except in the case of young children or
vulnerable adults where the parent, guardian or carer can be closer.
Ensure external contamination is removed from the neck of the measured person (e.g. by
wiping) and that the instrument is protected against contamination (e.g. by covering the
detector’s window with thin plastic film). This is particularly important when the measurement is
carried out close to the neck.
Make a background measurement at the same monitoring location as the expected dose
rate measurement over the thyroid while keeping potentially contaminated people at least 3 m
away. The background measurement can be determined by measuring the thyroid of an
uncontaminated person. Alternatively, an uncontaminated part of the body (usually thigh,
forearm or shoulder) can be used for background measurements especially in cases where the
detector is close to the skin. If this is not possible then the ambient background can be measured
by holding the instrument up and taking the reading.
Make the dose rate/count-rate measurement at the same monitoring location.
Record the dose rate/count-rate reading for the background measurement and that for
thyroid measurement. Record the units of the measured quantity.
Calculate the net dose rate/count-rate by subtracting the background measurement from the
thyroid measurement.
Write a short measurement report (see below).
If possible, repeat the measurement within the next few days and record the result with
the previous one.
iv. How to avoid giving erroneous results
Read and follow the instruction manual of the instrument and any measurement procedure that
has been specified.
Carry out the dose rate/count rate measurement, preferably on people who have removed any
external contamination.
Be sure the ambient (background) dose rate/count rate is subtracted before interpretation of the
result.
37
Section II.6. Thyroid measurements made by members of public
Recommendations (continued)
v. How to report results
Record results for reporting according to a simple protocol. The following information should be
included:
Date of measurement
Place of measurement
Name
Age
Sex
Stable iodine taken? (Yes/No)
The date and time when the stable iodine was taken, if appropriate
Neck-to-instrument distance (at contact, or distance in cm)
Background dose rate/count-rate reading (including the unit of measurement)
The method used to measure the background (e.g. a measurement of the thyroid of an
uncontaminated person, or of an uncontaminated part of the body, or of the ambient
background)
Dose rate/count rate reading measured over the thyroid (including the unit of
measurement)
The net dose rate/count-rate value as calculated (including the unit of measurement).
Instrument manufacturer and model
Instrument settings
A photograph of the measurement technique, as appropriate.
Keep the report with you.
Contact the local radiation protection service for further instructions.
vi. How to interpret results
Dose rate/count rate can be converted directly into 131I activity in thyroid using the results of
calibration using a thyroid phantom (Section II.2). The thyroid absorbed dose or the committed
effective dose can be determined directly only if the time between intake and measurement and
the age of the measured subject is known.
Provided that the instrument has been properly calibrated, the tables given in Section III can be
used to determine the thyroid doses or committed effective doses from thyroid activity. These
assessments of dose should only be performed by trained staff.
The net dose rate value measured over the thyroid can be compared with the default
operational intervention level (OIL) for thyroid monitoring given by IAEA (IAEA, 2017). The
default value for the OIL for thyroid monitoring is 0.5 Sv/h above background and is applicable
for gamma dose rate meters that meet the following criteria:
- An effective window area <15 cm²
- A response greater than 0.1 Sv/h per kBq of I-131 in thyroid
If the measurement is taken within one week following intake and if the background ambient
dose is less than 0.25Sv/h the IAEA (IAEA, 2017) states that:
- if the net dose rate (i.e. background subtracted) is less than 0.5 Sv/h no action is needed
- if the net dose rate is greater than 0.5 Sv/h stable iodine should be taken and medical
screening provided.
38
Section II.6. Thyroid measurements made by members of public
Recommendations (continued)
In these recommendations, the administration of stable iodine is only recommended provided
medical advice has been obtained, and then only if the stable iodine is taken 24 or 48 hours at
most before an intake, or up to 10 hours after intake. If the dose rate exceeds the default OIL of
0.5 Sv/h, for the measurement conditions described above, radiation protection specialists
should be consulted.
For measurements that take place within the second week after intake, the OIL should be
reduced by a factor of 2.5 because the dose per unit content of 131I is approximately 2.5 times
higher at 14 days compared with at 7 days.
39
References for section II
AFNOR 2013 NF S92-503 Laboratoire de biologie médicale —Mesures anthroporadiométriques — Thyroïde —
Mesures des émissions gamma des isotopes de l'iode, ISSN 0335-3931.
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41
III GUIDELINES ON DOSE ASSESSMENT FOR ADULT, CHILD, EMBRYO
AND FOETUS FROM MEASUREMENTS OF RADIOIODINE IN THE
THYROID GLAND
III.1 Introduction
In this section dosimetric data is provided to determine the committed absorbed dose to the thyroid
integrated over 30 days4and the associated committed effective dose from measurements of I-131
and I-132 in the thyroid. Tabulated values of Dose per Content Functions [Berkovski et al., 2003] for
radioiodine in thyroid are given for adult, child and foetus. These functions have been calculated
using ICRP biokinetic and dosimetric models [ICRP, 1989, 1994, 2001], [Berkovski, 1999, 2002] with
the methodology of ICRP Publication 60 [ICRP, 1990] and IDSS/IMIE computer codes [Berkovski et al.,
1998, 2007]. Recommendations are also given on the application of these dose per content
functions. International dose criteria for which protective actions and other response actions are
expected to be undertaken under any circumstances to avoid or to minimise severe deterministic
effects5[IAEA, 2014], are expressed in terms of the committed absorbed dose to the thyroid
integrated over 30 days weighted by the relative biological effectiveness of radioiodine. Numerical
values of the committed absorbed dose to the thyroid integrated over 30 days provided in this
section can be used as a good approximation of numerical values of the committed equivalent dose
to the thyroid integrated over the infinite period of time. It should be noted that the quantity
“equivalent dose to an organ or tissue” is not intended to be used as a protective quantity in case of
tissue reactions.
Further details of the data presented here and the methods used to calculate them are given in the
Scientific Report of CAThyMARA Work Package 6 [Vrba et al 2017]. The scope of applicability of the
data and methods given in this section is described in sub-section 0.
III.2 Input information
The absorbed dose to the thyroid gland and the associated committed effective dose from intake of
I-131 can be assessed from the following input data:
The measured activity content of the I-131 in the thyroid gland Mିଵଷଵ(T)(Bq) at the time T
after the intake;
The age of an individual. For the purposes of this document, the age should be categorised as
associated with one of reference age groups A(see Table III.1) or with one of the reference
gestational age groups Af(see Table III.2).
Figure III.1 illustrates the application of methods
4See definition of this quantity in sub-section 4.9.
5The International Safety Standards recommend the criteria as the RBE-weighted absorbed dose of 2 Gy to
thyroid with RBE value of 0.2 for I-131 and of 1 for other thyroid seekers [IAEA, 2014 Table IV.1 and p. 417]. The
RBE-weighting can be applied to quantities provided in this section in accordance the most up-to-date scientific
information.
Action levels in terms of effective dose for internal contamination are also given in the TMT Handbook [Rojas
Palma et al., 2009]. An upper level corresponding to a committed effective dose of 200 mSv is associated with
urgent actions while a lower level, which can be considered as a variable, is associated with less urgent actions.
A ratio of the upper action level to lower action level should initially be set at 10, and could be increased
depending on resources available but is unlikely to exceed 200.
42
Figure III.1. Flowchart of application of methods for the assessment of: committed absorbed dose
to thyroid integrated over 30 days (left panel) and committed effective dose (right panel) from
intake of radio-iodine isotopes.
Tables are given for the committed absorbed dose to the thyroid integrated over 30 days and the
corresponding committed effective dose per content of I-131 in thyroid following intakes of I-131
only with no accompanying short-lived radionuclides (Table III.3 and Table III.4).
On early stages of a nuclear emergency at a light water power reactor (LWR), the intake of I-131 can
be accompanied by intakes of other short-lived radio-iodines I-132, I-133, I-134, I-135, and Te-132. In
this case, the dose to the thyroid gland can be adjusted with the use of correction coefficients (Table
III.5), which are based on the reference isotopic ratios between I-131 and other listed above
radionuclides in the environmental source terms of the LWR (“reference mixture” – see Table III.11).
Such correction coefficients depend on the time τ elapsed from the moment when the nuclear
reaction ceased to the moment of intake (Table III.5 and Table III.7).
Table III.1. Reference age groups Afor dose estimations [ICRP, 1989].
Age group
Age range
Infant from 0 to 12
1 year from 1 year to 2
5 years from 2 years to 7
10 years from 7 years to
15 years from 12 years to
Adult more than 17
43
Table III.2. Reference gestational age groups for estimations of foetus doses [ICRP, 2001].
Gestational age
Gestational age
conception from 0 to 2
5 weeks from 2 to 8
10 weeks from 8 to 12
15 weeks from 12 to 20
25 weeks from 12 years to
35 weeks more than 30
In situations where I-132 is measured in the thyroid as well as I-131 using spectrometric instruments,
dosimetric data is provided to assess committed absorbed doses to the thyroid and committed
effective doses. For these assessments, tables are in terms of dose per content of I-132 in the thyroid
following intake of Te-132 (Table III.6 and Table III.8). Correction factors are also given in Table III.7 to
be applied to the dose per content of I-131 in the thyroid following intake of I-131 to account for the
additional intakes of the short-lived radio-isotopes of iodine (I-132, I-133, I-134 and I-135).
Dosimetric data are also provided to estimate the committed absorbed dose to the foetal thyroid
gland based on measurements of I-131 and I-132 in the maternal thyroid gland (Table III.9 and where
ܦܫ
−131݂,ܶܶ,ܣ݂
is the dose assessed with the equation (3.9);
C2(τ) is the correction coefficient for the time τafter the reactor shutdown (Table III.7).
Table III.10).
III.3 Thyroid dose from intake of I-131 estimated based on the I-131 content
in the thyroid gland
The committed absorbed dose ܦିଵଷ
்௛()(ܶ,ܣ), Gy to the thyroid gland at the 30th day after acute
intake of I-131 should be estimated as:
ܦିଵଷ
்௛()(ܶ,ܣ)=ܯିଵଷ(ܶ)ݖ
ିଵଷ
்௛()(ܶ,ܣ), (3.1)
where
ܯିଵଷ(ܶ)is the measured I-131 content in the thyroid gland at the time Tafter the intake, Bq;
ݖ
ିଵଷ
்௛()(ܶ,ܣ)is the tabulated function given in Table III.3, Gy Bq-1.
Table III.3. Committed absorbed dose to the thyroid gland on the 30th day after acute intake of I-
131 per content of I-131 in the thyroid gland at the time Tafter the intake (for a member of public,
reference age groups) ((૙ࢊ)
ି૚૜૚ (,)), Gy per Bq.
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
0.125 4.9E-05 4.7E-05 2.7E-05 1.3E-05 8.6E-06 5.4E-06
0.25 2.7E-05 2.6E-05 1.5E-05 7.2E-06 4.7E-06 3.0E-06
0.375 2.0E-05 1.9E-05 1.1E-05 5.5E-06 3.6E-06 2.3E-06
0.5 1.8E-05 1.7E-05 9.6E-06 4.7E-06 3.1E-06 1.9E-06
0.625 1.6E-05 1.5E-05 8.8E-06 4.3E-06 2.8E-06 1.8E-06
0.75 1.5E-05 1.5E-05 8.3E-06 4.1E-06 2.7E-06 1.7E-06
0.875 1.5E-05 1.4E-05 8.1E-06 4.0E-06 2.6E-06 1.6E-06
1 1.5E-05 1.4E-05 7.9E-06 3.9E-06 2.5E-06 1.6E-06
1.125 1.5E-05 1.4E-05 7.9E-06 3.9E-06 2.5E-06 1.6E-06
44
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
1.25 1.5E-05 1.4E-05 7.9E-06 3.8E-06 2.5E-06 1.6E-06
1.375 1.5E-05 1.4E-05 7.9E-06 3.9E-06 2.5E-06 1.6E-06
1.5 1.5E-05 1.4E-05 8.0E-06 3.9E-06 2.5E-06 1.6E-06
1.625 1.5E-05 1.4E-05 8.0E-06 3.9E-06 2.5E-06 1.6E-06
1.75 1.5E-05 1.5E-05 8.1E-06 3.9E-06 2.6E-06 1.6E-06
1.875 1.6E-05 1.5E-05 8.2E-06 4.0E-06 2.6E-06 1.6E-06
2 1.6E-05 1.5E-05 8.3E-06 4.0E-06 2.6E-06 1.7E-06
2.25 1.6E-05 1.5E-05 8.6E-06 4.1E-06 2.7E-06 1.7E-06
2.5 1.7E-05 1.6E-05 8.8E-06 4.2E-06 2.7E-06 1.7E-06
2.75 1.8E-05 1.6E-05 9.0E-06 4.3E-06 2.8E-06 1.8E-06
3 1.8E-05 1.7E-05 9.3E-06 4.4E-06 2.9E-06 1.8E-06
3.25 1.9E-05 1.7E-05 9.6E-06 4.5E-06 2.9E-06 1.9E-06
3.5 1.9E-05 1.8E-05 9.8E-06 4.6E-06 3.0E-06 1.9E-06
3.75 2.0E-05 1.8E-05 1.0E-05 4.7E-06 3.1E-06 1.9E-06
4 2.1E-05 1.9E-05 1.0E-05 4.9E-06 3.2E-06 2.0E-06
4.25 2.1E-05 2.0E-05 1.1E-05 5.0E-06 3.2E-06 2.0E-06
4.5 2.2E-05 2.0E-05 1.1E-05 5.1E-06 3.3E-06 2.1E-06
4.75 2.3E-05 2.1E-05 1.1E-05 5.2E-06 3.4E-06 2.1E-06
5 2.4E-05 2.2E-05 1.2E-05 5.4E-06 3.5E-06 2.2E-06
5.5 2.5E-05 2.3E-05 1.2E-05 5.6E-06 3.6E-06 2.3E-06
6 2.7E-05 2.4E-05 1.3E-05 5.9E-06 3.8E-06 2.4E-06
6.5 2.9E-05 2.6E-05 1.4E-05 6.2E-06 4.0E-06 2.5E-06
7 3.1E-05 2.8E-05 1.4E-05 6.5E-06 4.2E-06 2.6E-06
7.5 3.3E-05 2.9E-05 1.5E-05 6.8E-06 4.4E-06 2.8E-06
8 3.5E-05 3.1E-05 1.6E-05 7.2E-06 4.6E-06 2.9E-06
8.5 3.8E-05 3.3E-05 1.7E-05 7.5E-06 4.8E-06 3.0E-06
9 4.0E-05 3.5E-05 1.8E-05 7.9E-06 5.1E-06 3.2E-06
9.5 4.3E-05 3.7E-05 1.9E-05 8.3E-06 5.3E-06 3.3E-06
10 4.6E-05 4.0E-05 2.0E-05 8.7E-06 5.6E-06 3.5E-06
11 5.2E-05 4.5E-05 2.2E-05 9.6E-06 6.2E-06 3.8E-06
12 6.0E-05 5.0E-05 2.5E-05 1.1E-05 6.8E-06 4.2E-06
13 6.8E-05 5.7E-05 2.8E-05 1.2E-05 7.4E-06 4.6E-06
14 7.8E-05 6.4E-05 3.1E-05 1.3E-05 8.2E-06 5.1E-06
15 8.8E-05 7.2E-05 3.5E-05 1.4E-05 9.0E-06 5.6E-06
16 1.0E-04 8.1E-05 3.9E-05 1.5E-05 9.9E-06 6.1E-06
17 1.1E-04 9.2E-05 4.3E-05 1.7E-05 1.1E-05 6.7E-06
18 1.3E-04 1.0E-04 4.8E-05 1.9E-05 1.2E-05 7.4E-06
19 1.5E-04 1.2E-04 5.3E-05 2.1E-05 1.3E-05 8.1E-06
20 1.7E-04 1.3E-04 6.0E-05 2.3E-05 1.4E-05 8.9E-06
21 1.9E-04 1.5E-04 6.6E-05 2.5E-05 1.6E-05 9.8E-06
22 2.2E-04 1.7E-04 7.4E-05 2.7E-05 1.7E-05 1.1E-05
23 2.5E-04 1.9E-04 8.2E-05 3.0E-05 1.9E-05 1.2E-05
24 2.9E-04 2.1E-04 9.2E-05 3.3E-05 2.1E-05 1.3E-05
25 3.3E-04 2.4E-04 1.0E-04 3.6E-05 2.3E-05 1.4E-05
26 3.7E-04 2.7E-04 1.1E-04 4.0E-05 2.5E-05 1.6E-05
27 4.3E-04 3.0E-04 1.3E-04 4.4E-05 2.8E-05 1.7E-05
28 4.8E-04 3.4E-04 1.4E-04 4.8E-05 3.1E-05 1.9E-05
29 5.5E-04 3.9E-04 1.6E-04 5.3E-05 3.4E-05 2.1E-05
30 6.3E-04 4.4E-04 1.8E-04 5.9E-05 3.7E-05 2.3E-05
31 7.2E-04 4.9E-04 2.0E-04 6.4E-05 4.1E-05 2.5E-05
32 8.2E-04 5.6E-04 2.2E-04 7.1E-05 4.5E-05 2.7E-05
33 9.3E-04 6.3E-04 2.4E-04 7.8E-05 4.9E-05 3.0E-05
34 1.1E-03 7.1E-04 2.7E-04 8.6E-05 5.4E-05 3.3E-05
35 1.2E-03 8.0E-04 3.0E-04 9.4E-05 5.9E-05 3.6E-05
36 1.4E-03 9.0E-04 3.4E-04 1.0E-04 6.5E-05 4.0E-05
37 1.6E-03 1.0E-03 3.8E-04 1.1E-04 7.1E-05 4.3E-05
38 1.8E-03 1.1E-03 4.2E-04 1.3E-04 7.8E-05 4.8E-05
39 2.0E-03 1.3E-03 4.7E-04 1.4E-04 8.6E-05 5.2E-05
40 2.3E-03 1.5E-03 5.2E-04 1.5E-04 9.4E-05 5.7E-05
45
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
41 2.6E-03 1.6E-03 5.8E-04 1.7E-04 1.0E-04 6.3E-05
42 3.0E-03 1.8E-03 6.4E-04 1.8E-04 1.1E-04 6.9E-05
43 3.4E-03 2.1E-03 7.2E-04 2.0E-04 1.3E-04 7.6E-05
44 3.9E-03 2.3E-03 8.0E-04 2.2E-04 1.4E-04 8.3E-05
45 4.4E-03 2.6E-03 8.9E-04 2.4E-04 1.5E-04 9.1E-05
46 5.0E-03 3.0E-03 9.9E-04 2.7E-04 1.7E-04 1.0E-04
47 5.7E-03 3.4E-03 1.1E-03 2.9E-04 1.8E-04 1.1E-04
48 6.5E-03 3.8E-03 1.2E-03 3.2E-04 2.0E-04 1.2E-04
49 7.5E-03 4.3E-03 1.4E-03 3.6E-04 2.2E-04 1.3E-04
50 8.5E-03 4.8E-03 1.5E-03 3.9E-04 2.4E-04 1.5E-04
51 9.7E-03 5.4E-03 1.7E-03 4.3E-04 2.7E-04 1.6E-04
52 1.1E-02 6.1E-03 1.9E-03 4.7E-04 2.9E-04 1.7E-04
53 1.3E-02 6.9E-03 2.1E-03 5.2E-04 3.2E-04 1.9E-04
54 1.4E-02 7.8E-03 2.4E-03 5.7E-04 3.5E-04 2.1E-04
55 1.6E-02 8.8E-03 2.6E-03 6.3E-04 3.9E-04 2.3E-04
56 1.8E-02 9.9E-03 2.9E-03 6.9E-04 4.2E-04 2.5E-04
57 2.1E-02 1.1E-02 3.3E-03 7.6E-04 4.7E-04 2.8E-04
58 2.4E-02 1.3E-02 3.6E-03 8.4E-04 5.1E-04 3.0E-04
59 2.7E-02 1.4E-02 4.0E-03 9.2E-04 5.6E-04 3.3E-04
60 3.1E-02 1.6E-02 4.5E-03 1.0E-03 6.2E-04 3.7E-04
61 3.5E-02 1.8E-02 5.0E-03 1.1E-03 6.8E-04 4.0E-04
62 4.0E-02 2.0E-02 5.6E-03 1.2E-03 7.4E-04 4.4E-04
63 4.6E-02 2.3E-02 6.2E-03 1.3E-03 8.2E-04 4.8E-04
64 5.2E-02 2.6E-02 6.9E-03 1.5E-03 9.0E-04 5.3E-04
65 5.9E-02 2.9E-02 7.7E-03 1.6E-03 9.9E-04 5.8E-04
66 6.7E-02 3.3E-02 8.6E-03 1.8E-03 1.1E-03 6.4E-04
67 7.6E-02 3.7E-02 9.6E-03 2.0E-03 1.2E-03 7.0E-04
68 8.7E-02 4.2E-02 1.1E-02 2.2E-03 1.3E-03 7.7E-04
69 9.9E-02 4.7E-02 1.2E-02 2.4E-03 1.4E-03 8.4E-04
70 1.1E-01 5.3E-02 1.3E-02 2.6E-03 1.6E-03 9.3E-04
71 1.3E-01 6.0E-02 1.5E-02 2.9E-03 1.7E-03 1.0E-03
72 1.5E-01 6.7E-02 1.6E-02 3.2E-03 1.9E-03 1.1E-03
73 1.7E-01 7.6E-02 1.8E-02 3.5E-03 2.1E-03 1.2E-03
74 1.9E-01 8.5E-02 2.0E-02 3.8E-03 2.3E-03 1.3E-03
75 2.1E-01 9.6E-02 2.3E-02 4.2E-03 2.5E-03 1.5E-03
76 2.4E-01 1.1E-01 2.5E-02 4.6E-03 2.8E-03 1.6E-03
77 2.8E-01 1.2E-01 2.8E-02 5.1E-03 3.0E-03 1.8E-03
78 3.1E-01 1.4E-01 3.1E-02 5.6E-03 3.3E-03 1.9E-03
79 3.6E-01 1.6E-01 3.5E-02 6.2E-03 3.7E-03 2.1E-03
80 4.1E-01 1.7E-01 3.9E-02 6.8E-03 4.0E-03 2.3E-03
81 4.6E-01 2.0E-01 4.4E-02 7.5E-03 4.4E-03 2.6E-03
82 5.3E-01 2.2E-01 4.8E-02 8.2E-03 4.9E-03 2.8E-03
83 6.0E-01 2.5E-01 5.4E-02 9.0E-03 5.3E-03 3.1E-03
84 6.8E-01 2.8E-01 6.0E-02 9.9E-03 5.9E-03 3.4E-03
85 7.7E-01 3.2E-01 6.7E-02 1.1E-02 6.4E-03 3.7E-03
86 8.8E-01 3.6E-01 7.5E-02 1.2E-02 7.1E-03 4.1E-03
87 1.0E+00 4.0E-01 8.3E-02 1.3E-02 7.8E-03 4.5E-03
88 1.1E+00 4.6E-01 9.3E-02 1.5E-02 8.5E-03 4.9E-03
89 1.3E+00 5.1E-01 1.0E-01 1.6E-02 9.4E-03 5.4E-03
90 1.5E+00 5.8E-01 1.1E-01 1.8E-02 1.0E-02 5.9E-03
91 1.7E+00 6.5E-01 1.3E-01 1.9E-02 1.1E-02 6.5E-03
92 1.9E+00 7.3E-01 1.4E-01 2.1E-02 1.2E-02 7.1E-03
93 2.1E+00 8.3E-01 1.6E-01 2.3E-02 1.4E-02 7.8E-03
94 2.4E+00 9.3E-01 1.8E-01 2.6E-02 1.5E-02 8.5E-03
95 2.8E+00 1.1E+00 2.0E-01 2.8E-02 1.6E-02 9.4E-03
96 3.1E+00 1.2E+00 2.2E-01 3.1E-02 1.8E-02 1.0E-02
97 3.6E+00 1.3E+00 2.4E-01 3.4E-02 2.0E-02 1.1E-02
98 4.1E+00 1.5E+00 2.7E-01 3.8E-02 2.2E-02 1.2E-02
99 4.6E+00 1.7E+00 3.0E-01 4.1E-02 2.4E-02 1.4E-02
46
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
100 5.2E+00 1.9E+00 3.4E-01 4.5E-02 2.6E-02 1.5E-02
III.4 Effective dose from intake of I-131 estimated based on the I-131 content
in the thyroid gland
The committed effective dose ݁
ିଵଷ(ܶ,ܣ), Sv after acute intake of the I-131 should be estimated as:
݁
ିଵଷ(ܶ,ܣ)=ܯିଵଷ(ܶ)ݖ
ିଵଷ
(ܶ,ܣ), (3.2)
where
ܯିଵଷ(ܶ)is the measured I-131 content in the thyroid gland at the time Tafter the intake, Bq;
ݖ
ିଵଷ
(ܶ,ܣ)is the tabulated function given in Table III.4, Sv Bq-1.
Table III.4. Committed effective dose from intake of I-131 per content of I-131 in the thyroid gland
at time Tafter the intake (for a member of public, reference age groups) (ି૚૜
(,)),
Sv per Bq.
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
0.125 2.5E-06 2.4E-06 1.4E-06 7.1E-07 4.6E-07 2.9E-07
0.25 1.4E-06 1.3E-06 7.6E-07 3.9E-07 2.5E-07 1.6E-07
0.375 1.0E-06 1.0E-06 5.8E-07 2.9E-07 1.9E-07 1.2E-07
0.5 9.0E-07 8.7E-07 5.0E-07 2.5E-07 1.6E-07 1.0E-07
0.625 8.3E-07 8.0E-07 4.6E-07 2.3E-07 1.5E-07 9.5E-08
0.75 7.9E-07 7.6E-07 4.3E-07 2.2E-07 1.4E-07 9.0E-08
0.875 7.7E-07 7.4E-07 4.2E-07 2.1E-07 1.4E-07 8.8E-08
1 7.6E-07 7.2E-07 4.2E-07 2.1E-07 1.4E-07 8.6E-08
1.125 7.5E-07 7.2E-07 4.1E-07 2.1E-07 1.3E-07 8.5E-08
1.25 7.6E-07 7.2E-07 4.1E-07 2.1E-07 1.3E-07 8.5E-08
1.375 7.6E-07 7.3E-07 4.1E-07 2.1E-07 1.3E-07 8.5E-08
1.5 7.7E-07 7.3E-07 4.2E-07 2.1E-07 1.3E-07 8.6E-08
1.625 7.8E-07 7.4E-07 4.2E-07 2.1E-07 1.4E-07 8.6E-08
1.75 7.9E-07 7.5E-07 4.3E-07 2.1E-07 1.4E-07 8.7E-08
1.875 8.0E-07 7.6E-07 4.3E-07 2.1E-07 1.4E-07 8.8E-08
2 8.1E-07 7.7E-07 4.4E-07 2.1E-07 1.4E-07 8.9E-08
2.25 8.4E-07 7.9E-07 4.5E-07 2.2E-07 1.4E-07 9.1E-08
2.5 8.7E-07 8.2E-07 4.6E-07 2.2E-07 1.5E-07 9.3E-08
2.75 9.0E-07 8.4E-07 4.7E-07 2.3E-07 1.5E-07 9.5E-08
3 9.3E-07 8.7E-07 4.9E-07 2.4E-07 1.5E-07 9.7E-08
3.25 9.6E-07 9.0E-07 5.0E-07 2.4E-07 1.6E-07 9.9E-08
3.5 1.0E-06 9.3E-07 5.1E-07 2.5E-07 1.6E-07 1.0E-07
3.75 1.0E-06 9.6E-07 5.3E-07 2.5E-07 1.6E-07 1.0E-07
4 1.1E-06 9.9E-07 5.4E-07 2.6E-07 1.7E-07 1.1E-07
4.25 1.1E-06 1.0E-06 5.6E-07 2.7E-07 1.7E-07 1.1E-07
4.5 1.1E-06 1.0E-06 5.7E-07 2.7E-07 1.8E-07 1.1E-07
4.75 1.2E-06 1.1E-06 5.9E-07 2.8E-07 1.8E-07 1.1E-07
5 1.2E-06 1.1E-06 6.1E-07 2.9E-07 1.9E-07 1.2E-07
5.5 1.3E-06 1.2E-06 6.4E-07 3.0E-07 1.9E-07 1.2E-07
6 1.4E-06 1.3E-06 6.8E-07 3.1E-07 2.0E-07 1.3E-07
6.5 1.5E-06 1.3E-06 7.2E-07 3.3E-07 2.1E-07 1.4E-07
7 1.6E-06 1.4E-06 7.6E-07 3.5E-07 2.2E-07 1.4E-07
7.5 1.7E-06 1.5E-06 8.0E-07 3.6E-07 2.4E-07 1.5E-07
8 1.8E-06 1.6E-06 8.4E-07 3.8E-07 2.5E-07 1.6E-07
8.5 1.9E-06 1.7E-06 8.9E-07 4.0E-07 2.6E-07 1.6E-07
9 2.1E-06 1.8E-06 9.4E-07 4.2E-07 2.7E-07 1.7E-07
47
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
9.5 2.2E-06 1.9E-06 1.0E-06 4.4E-07 2.9E-07 1.8E-07
10 2.4E-06 2.0E-06 1.1E-06 4.6E-07 3.0E-07 1.9E-07
11 2.7E-06 2.3E-06 1.2E-06 5.1E-07 3.3E-07 2.1E-07
12 3.1E-06 2.6E-06 1.3E-06 5.6E-07 3.6E-07 2.3E-07
13 3.5E-06 2.9E-06 1.5E-06 6.2E-07 4.0E-07 2.5E-07
14 4.0E-06 3.3E-06 1.6E-06 6.8E-07 4.4E-07 2.7E-07
15 4.5E-06 3.7E-06 1.8E-06 7.5E-07 4.8E-07 3.0E-07
16 5.2E-06 4.2E-06 2.0E-06 8.2E-07 5.3E-07 3.3E-07
17 5.9E-06 4.7E-06 2.2E-06 9.1E-07 5.8E-07 3.6E-07
18 6.7E-06 5.3E-06 2.5E-06 1.0E-06 6.4E-07 4.0E-07
19 7.7E-06 6.0E-06 2.8E-06 1.1E-06 7.0E-07 4.4E-07
20 8.7E-06 6.8E-06 3.1E-06 1.2E-06 7.7E-07 4.8E-07
21 1.0E-05 7.7E-06 3.5E-06 1.3E-06 8.5E-07 5.3E-07
22 1.1E-05 8.6E-06 3.9E-06 1.5E-06 9.3E-07 5.8E-07
23 1.3E-05 9.7E-06 4.3E-06 1.6E-06 1.0E-06 6.3E-07
24 1.5E-05 1.1E-05 4.8E-06 1.8E-06 1.1E-06 7.0E-07
25 1.7E-05 1.2E-05 5.3E-06 1.9E-06 1.2E-06 7.6E-07
26 1.9E-05 1.4E-05 6.0E-06 2.1E-06 1.4E-06 8.4E-07
27 2.2E-05 1.6E-05 6.6E-06 2.3E-06 1.5E-06 9.2E-07
28 2.5E-05 1.8E-05 7.4E-06 2.6E-06 1.6E-06 1.0E-06
29 2.8E-05 2.0E-05 8.2E-06 2.8E-06 1.8E-06 1.1E-06
30 3.2E-05 2.3E-05 9.2E-06 3.1E-06 2.0E-06 1.2E-06
31 3.7E-05 2.5E-05 1.0E-05 3.4E-06 2.2E-06 1.3E-06
32 4.2E-05 2.9E-05 1.1E-05 3.8E-06 2.4E-06 1.5E-06
33 4.8E-05 3.2E-05 1.3E-05 4.2E-06 2.6E-06 1.6E-06
34 5.4E-05 3.6E-05 1.4E-05 4.6E-06 2.9E-06 1.8E-06
35 6.2E-05 4.1E-05 1.6E-05 5.0E-06 3.2E-06 1.9E-06
36 7.1E-05 4.6E-05 1.8E-05 5.5E-06 3.5E-06 2.1E-06
37 8.0E-05 5.2E-05 2.0E-05 6.1E-06 3.8E-06 2.3E-06
38 9.2E-05 5.9E-05 2.2E-05 6.7E-06 4.2E-06 2.6E-06
39 1.0E-04 6.6E-05 2.4E-05 7.4E-06 4.6E-06 2.8E-06
40 1.2E-04 7.5E-05 2.7E-05 8.1E-06 5.1E-06 3.1E-06
41 1.4E-04 8.4E-05 3.0E-05 8.9E-06 5.5E-06 3.4E-06
42 1.5E-04 9.5E-05 3.4E-05 9.8E-06 6.1E-06 3.7E-06
43 1.8E-04 1.1E-04 3.8E-05 1.1E-05 6.7E-06 4.1E-06
44 2.0E-04 1.2E-04 4.2E-05 1.2E-05 7.4E-06 4.5E-06
45 2.3E-04 1.4E-04 4.7E-05 1.3E-05 8.1E-06 4.9E-06
46 2.6E-04 1.5E-04 5.2E-05 1.4E-05 8.9E-06 5.4E-06
47 3.0E-04 1.7E-04 5.8E-05 1.6E-05 9.7E-06 5.9E-06
48 3.4E-04 2.0E-04 6.4E-05 1.7E-05 1.1E-05 6.5E-06
49 3.8E-04 2.2E-04 7.2E-05 1.9E-05 1.2E-05 7.1E-06
50 4.4E-04 2.5E-04 8.0E-05 2.1E-05 1.3E-05 7.8E-06
51 5.0E-04 2.8E-04 8.9E-05 2.3E-05 1.4E-05 8.5E-06
52 5.6E-04 3.2E-04 9.9E-05 2.5E-05 1.6E-05 9.4E-06
53 6.4E-04 3.6E-04 1.1E-04 2.8E-05 1.7E-05 1.0E-05
54 7.3E-04 4.0E-04 1.2E-04 3.1E-05 1.9E-05 1.1E-05
55 8.3E-04 4.5E-04 1.4E-04 3.4E-05 2.1E-05 1.2E-05
56 9.5E-04 5.1E-04 1.5E-04 3.7E-05 2.3E-05 1.4E-05
57 1.1E-03 5.8E-04 1.7E-04 4.1E-05 2.5E-05 1.5E-05
58 1.2E-03 6.5E-04 1.9E-04 4.5E-05 2.7E-05 1.6E-05
59 1.4E-03 7.3E-04 2.1E-04 4.9E-05 3.0E-05 1.8E-05
60 1.6E-03 8.2E-04 2.4E-04 5.4E-05 3.3E-05 2.0E-05
61 1.8E-03 9.3E-04 2.6E-04 6.0E-05 3.6E-05 2.2E-05
62 2.1E-03 1.0E-03 2.9E-04 6.5E-05 4.0E-05 2.4E-05
63 2.3E-03 1.2E-03 3.3E-04 7.2E-05 4.4E-05 2.6E-05
64 2.7E-03 1.3E-03 3.6E-04 7.9E-05 4.8E-05 2.9E-05
65 3.0E-03 1.5E-03 4.0E-04 8.7E-05 5.3E-05 3.1E-05
66 3.4E-03 1.7E-03 4.5E-04 9.6E-05 5.8E-05 3.4E-05
67 3.9E-03 1.9E-03 5.0E-04 1.1E-04 6.4E-05 3.8E-05
48
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
68 4.5E-03 2.1E-03 5.6E-04 1.2E-04 7.0E-05 4.1E-05
69 5.1E-03 2.4E-03 6.2E-04 1.3E-04 7.7E-05 4.5E-05
70 5.8E-03 2.7E-03 6.9E-04 1.4E-04 8.4E-05 5.0E-05
71 6.6E-03 3.1E-03 7.7E-04 1.5E-04 9.3E-05 5.5E-05
72 7.5E-03 3.5E-03 8.6E-04 1.7E-04 1.0E-04 6.0E-05
73 8.5E-03 3.9E-03 9.6E-04 1.9E-04 1.1E-04 6.6E-05
74 9.7E-03 4.4E-03 1.1E-03 2.0E-04 1.2E-04 7.2E-05
75 1.1E-02 5.0E-03 1.2E-03 2.3E-04 1.3E-04 7.9E-05
76 1.2E-02 5.6E-03 1.3E-03 2.5E-04 1.5E-04 8.7E-05
77 1.4E-02 6.3E-03 1.5E-03 2.7E-04 1.6E-04 9.5E-05
78 1.6E-02 7.1E-03 1.6E-03 3.0E-04 1.8E-04 1.0E-04
79 1.8E-02 8.0E-03 1.8E-03 3.3E-04 2.0E-04 1.1E-04
80 2.1E-02 9.0E-03 2.0E-03 3.6E-04 2.2E-04 1.3E-04
81 2.4E-02 1.0E-02 2.3E-03 4.0E-04 2.4E-04 1.4E-04
82 2.7E-02 1.1E-02 2.5E-03 4.4E-04 2.6E-04 1.5E-04
83 3.1E-02 1.3E-02 2.8E-03 4.8E-04 2.9E-04 1.7E-04
84 3.5E-02 1.5E-02 3.1E-03 5.3E-04 3.1E-04 1.8E-04
85 4.0E-02 1.6E-02 3.5E-03 5.8E-04 3.4E-04 2.0E-04
86 4.5E-02 1.9E-02 3.9E-03 6.4E-04 3.8E-04 2.2E-04
87 5.1E-02 2.1E-02 4.3E-03 7.0E-04 4.2E-04 2.4E-04
88 5.8E-02 2.4E-02 4.8E-03 7.7E-04 4.6E-04 2.6E-04
89 6.6E-02 2.7E-02 5.4E-03 8.5E-04 5.0E-04 2.9E-04
90 7.5E-02 3.0E-02 6.0E-03 9.4E-04 5.5E-04 3.2E-04
91 8.5E-02 3.4E-02 6.7E-03 1.0E-03 6.1E-04 3.5E-04
92 9.7E-02 3.8E-02 7.4E-03 1.1E-03 6.6E-04 3.8E-04
93 1.1E-01 4.3E-02 8.3E-03 1.2E-03 7.3E-04 4.2E-04
94 1.3E-01 4.8E-02 9.2E-03 1.4E-03 8.0E-04 4.6E-04
95 1.4E-01 5.4E-02 1.0E-02 1.5E-03 8.8E-04 5.0E-04
96 1.6E-01 6.1E-02 1.1E-02 1.7E-03 9.7E-04 5.5E-04
97 1.8E-01 6.9E-02 1.3E-02 1.8E-03 1.1E-03 6.0E-04
98 2.1E-01 7.8E-02 1.4E-02 2.0E-03 1.2E-03 6.6E-04
99 2.4E-01 8.8E-02 1.6E-02 2.2E-03 1.3E-03 7.3E-04
100 2.7E-01 9.9E-02 1.8E-02 2.4E-03 1.4E-03 8.0E-04
III.5 Total dose from radio-iodine isotopes and Te-132 present in the source
term of a light water reactor estimated based on the dose from I-131
The dose estimated in accordance with (3.1) and (3.2) can be adjusted to include the contribution of
other short-lived radio-iodine isotopes and Te-132 present in the source term of a light water
reactor. The committed absorbed dose DTh(30d)(τ, T, A), Gy to the thyroid gland at the 30th day after
acute intake of I-131, I-132, I-133, I-134, I-135, and Te-132 should be estimated as:
ܦ்௛()(߬,ܶ,ܣ)=ܦିଵଷ
்௛()(ܶ,ܣ)ܥ(߬), (3.3)
where
ܦିଵଷ
்௛(଴ௗ)(ܶ,ܣ)is the dose assessed in accordance with Section 0.
C1(τ) is the correction coefficient for the time interval τbetween the time of the reactor shutdown
and the time of intake (Table III.5).
The committed effective dose e(τ, T, A) after acute intake of the mixture of radionuclides I-131, I-132,
I-133, I-134, I-135, and Te-132 should be estimated as:
݁(߬,ܶ,ܣ)=݁
ିଵଷ(ܶ,ܣ)ܥ(߬), (3.4)
where
݁
ିଵଷ(ܶ,ܣ)is the committed effective dose assessed in accordance with Section III.4.
49
Table III.5. Correction coefficients C1(τ).
Time interval τ, h C
1
(τ)Time interval τ, h C
1
(τ)
1 2.09 20 1.71
2 2.06 21 1.70
3 2.02 22 1.69
4 2.00 23 1.67
5 1.97 24 1.66
6 1.95 27 1.63
7 1.92 30 1.60
8 1.90 33 1.58
9 1.88 36 1.55
10 1.86 39 1.53
11 1.85 42 1.51
12 1.83 45 1.49
13 1.81 48 1.47
14 1.79 60 1.41
15 1.78 72 1.36
16 1.76 84 1.32
17 1.75 96 1.29
18 1.74 108 1.27
19 1.72 120 1.24
III.6 Doses from intake of radio-iodine isotopes and Te-132 estimated based
on measured I-131 and I-132 contents in the thyroid gland
If in addition to the measured I-131 content in the thyroid gland the measured I-132 content in the
thyroid gland is available after an accidental intake of radio-iodine isotopes and Te-132, then the
estimation of the committed absorbed dose to the thyroid and committed effective dose could be
performed as described below. The described technique conservatively assumes that all measured
content of I-132 in the thyroid gland is produced by the decay of Te-132 inside the human body.
The committed absorbed dose ܦ்௘ିଵଷ
்௛(଴ௗ)(ܶ,ܣ), Gy to the thyroid gland at the 30th day after acute
intake of the Te-132 should be assessed from the measured I-132 content in the thyroid gland as:
ܦ்௘ିଵଷ
்௛(଴ௗ)(ܶ,ܣ)=ܯିଵଷ(ܶ)ݖ
்௘ି ଵଷ
்௛(଴ௗ)(ܶ,ܣ), (3.5)
where
ܯିଵଷ(ܶ)is the measured I-132 content in the thyroid gland at the time Tafter the intake, Bq;
ݖ
்௘ିଵଷ
்௛(଴ௗ)(ܶ,ܣ)is the tabulated function given in Table III.6, Gy Bq-1.
The committed absorbed dose ܦ்௛(଴ௗ)(߬,ܶ,ܣ), Gy to the thyroid gland at the 30th day after acute
intake of the mixture of radionuclides I-131, I-132, I-133, I-134, I-135, and Te-132 should be assessed
as:
ܦ்௛(଴ௗ)(߬,ܶ,ܣ)=ܦିଵଷ
்௛(଴ௗ)(ܶ,ܣ)ܥ(߬
)+ܦ்௘ିଵଷ
்௛(଴ௗ)(ܶ,ܣ), (3.6)
where
ܦିଵଷ
்௛(଴ௗ)(ܶ,ܣ)is the dose assessed in accordance with Section 0;
50
C2(τ) is the correction coefficient for the time interval τbetween the time of the reactor shutdown
and the time of intake (Table III.7).
Table III.6. Committed absorbed doses to the thyroid gland on the 30th day after acute intake of
Te-132 per content of I-132 in the thyroid gland at the time Tafter the intake (for members of
public, reference age groups A) (ࢀࢋି૚૜
ࢀࢎ(૙ࢊ)(,)), Gy per Bq
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
0.125 4.4E-05 3.5E-05 1.9E-05 8.3E-06 5.6E-06 3.5E-06
0.25 2.1E-05 1.7E-05 9.0E-06 4.0E-06 2.7E-06 1.7E-06
0.375 1.7E-05 1.4E-05 7.4E-06 3.3E-06 2.2E-06 1.4E-06
0.5 1.6E-05 1.4E-05 7.3E-06 3.3E-06 2.1E-06 1.4E-06
0.625 1.7E-05 1.4E-05 7.6E-06 3.4E-06 2.2E-06 1.4E-06
0.75 1.7E-05 1.5E-05 8.1E-06 3.6E-06 2.3E-06 1.5E-06
0.875 1.8E-05 1.6E-05 8.6E-06 3.8E-06 2.5E-06 1.6E-06
1 2.0E-05 1.7E-05 9.2E-06 4.1E-06 2.7E-06 1.7E-06
1.125 2.1E-05 1.9E-05 9.8E-06 4.4E-06 2.8E-06 1.8E-06
1.25 2.2E-05 2.0E-05 1.0E-05 4.6E-06 3.0E-06 1.9E-06
1.375 2.3E-05 2.1E-05 1.1E-05 4.9E-06 3.2E-06 2.0E-06
1.5 2.5E-05 2.2E-05 1.2E-05 5.2E-06 3.4E-06 2.1E-06
1.625 2.6E-05 2.3E-05 1.2E-05 5.5E-06 3.6E-06 2.2E-06
1.75 2.7E-05 2.5E-05 1.3E-05 5.8E-06 3.7E-06 2.4E-06
1.875 2.9E-05 2.6E-05 1.4E-05 6.1E-06 3.9E-06 2.5E-06
2 3.0E-05 2.7E-05 1.4E-05 6.3E-06 4.1E-06 2.6E-06
2.25 3.3E-05 3.0E-05 1.6E-05 7.0E-06 4.5E-06 2.9E-06
2.5 3.6E-05 3.2E-05 1.7E-05 7.6E-06 4.9E-06 3.1E-06
2.75 3.9E-05 3.5E-05 1.8E-05 8.2E-06 5.3E-06 3.4E-06
3 4.2E-05 3.8E-05 2.0E-05 8.9E-06 5.8E-06 3.6E-06
3.25 4.6E-05 4.1E-05 2.1E-05 9.5E-06 6.2E-06 3.9E-06
3.5 4.9E-05 4.4E-05 2.3E-05 1.0E-05 6.7E-06 4.2E-06
3.75 5.2E-05 4.7E-05 2.5E-05 1.1E-05 7.1E-06 4.5E-06
4 5.6E-05 5.0E-05 2.6E-05 1.2E-05 7.6E-06 4.8E-06
4.25 6.0E-05 5.3E-05 2.8E-05 1.2E-05 8.1E-06 5.1E-06
4.5 6.4E-05 5.7E-05 3.0E-05 1.3E-05 8.6E-06 5.5E-06
4.75 6.8E-05 6.1E-05 3.2E-05 1.4E-05 9.2E-06 5.8E-06
5 7.2E-05 6.4E-05 3.4E-05 1.5E-05 9.8E-06 6.2E-06
5.5 8.1E-05 7.3E-05 3.8E-05 1.7E-05 1.1E-05 7.0E-06
6 9.1E-05 8.2E-05 4.3E-05 1.9E-05 1.2E-05 7.9E-06
6.5 1.0E-04 9.2E-05 4.8E-05 2.2E-05 1.4E-05 8.8E-06
7 1.2E-04 1.0E-04 5.4E-05 2.4E-05 1.6E-05 9.9E-06
7.5 1.3E-04 1.2E-04 6.1E-05 2.7E-05 1.8E-05 1.1E-05
8 1.5E-04 1.3E-04 6.8E-05 3.0E-05 2.0E-05 1.2E-05
8.5 1.6E-04 1.5E-04 7.6E-05 3.4E-05 2.2E-05 1.4E-05
9 1.8E-04 1.6E-04 8.6E-05 3.8E-05 2.5E-05 1.6E-05
9.5 2.0E-04 1.8E-04 9.6E-05 4.3E-05 2.8E-05 1.8E-05
10 2.3E-04 2.1E-04 1.1E-04 4.8E-05 3.1E-05 2.0E-05
11 2.9E-04 2.6E-04 1.4E-04 6.0E-05 3.9E-05 2.5E-05
12 3.6E-04 3.2E-04 1.7E-04 7.6E-05 4.9E-05 3.1E-05
13 4.5E-04 4.1E-04 2.1E-04 9.5E-05 6.2E-05 3.9E-05
14 5.7E-04 5.1E-04 2.7E-04 1.2E-04 7.8E-05 4.9E-05
15 7.2E-04 6.4E-04 3.4E-04 1.5E-04 9.7E-05 6.2E-05
16 9.0E-04 8.0E-04 4.2E-04 1.9E-04 1.2E-04 7.7E-05
17 1.1E-03 1.0E-03 5.3E-04 2.4E-04 1.5E-04 9.7E-05
18 1.4E-03 1.3E-03 6.6E-04 3.0E-04 1.9E-04 1.2E-04
19 1.8E-03 1.6E-03 8.3E-04 3.7E-04 2.4E-04 1.5E-04
20 2.2E-03 2.0E-03 1.0E-03 4.6E-04 3.0E-04 1.9E-04
21 2.8E-03 2.5E-03 1.3E-03 5.8E-04 3.8E-04 2.4E-04
22 3.5E-03 3.1E-03 1.6E-03 7.3E-04 4.7E-04 3.0E-04
23 4.4E-03 3.9E-03 2.0E-03 9.1E-04 5.9E-04 3.7E-04
24 5.5E-03 4.9E-03 2.6E-03 1.1E-03 7.4E-04 4.7E-04
51
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
25 6.8E-03 6.1E-03 3.2E-03 1.4E-03 9.3E-04 5.9E-04
26 8.5E-03 7.6E-03 4.0E-03 1.8E-03 1.2E-03 7.3E-04
27 1.1E-02 9.6E-03 5.0E-03 2.2E-03 1.5E-03 9.2E-04
28 1.3E-02 1.2E-02 6.3E-03 2.8E-03 1.8E-03 1.1E-03
29 1.7E-02 1.5E-02 7.8E-03 3.5E-03 2.3E-03 1.4E-03
30 2.1E-02 1.9E-02 9.8E-03 4.4E-03 2.8E-03 1.8E-03
31 2.6E-02 2.3E-02 1.2E-02 5.5E-03 3.5E-03 2.2E-03
32 3.3E-02 2.9E-02 1.5E-02 6.8E-03 4.4E-03 2.8E-03
33 4.1E-02 3.6E-02 1.9E-02 8.5E-03 5.5E-03 3.5E-03
34 5.1E-02 4.5E-02 2.4E-02 1.1E-02 6.9E-03 4.4E-03
35 6.3E-02 5.7E-02 3.0E-02 1.3E-02 8.6E-03 5.4E-03
36 7.9E-02 7.1E-02 3.7E-02 1.7E-02 1.1E-02 6.8E-03
37 9.9E-02 8.8E-02 4.6E-02 2.1E-02 1.3E-02 8.5E-03
38 1.2E-01 1.1E-01 5.8E-02 2.6E-02 1.7E-02 1.1E-02
39 1.5E-01 1.4E-01 7.2E-02 3.2E-02 2.1E-02 1.3E-02
40 1.9E-01 1.7E-01 9.0E-02 4.0E-02 2.6E-02 1.6E-02
41 2.4E-01 2.1E-01 1.1E-01 5.0E-02 3.2E-02 2.1E-02
42 3.0E-01 2.7E-01 1.4E-01 6.2E-02 4.0E-02 2.6E-02
43 3.7E-01 3.3E-01 1.7E-01 7.8E-02 5.0E-02 3.2E-02
44 4.6E-01 4.1E-01 2.2E-01 9.7E-02 6.3E-02 4.0E-02
45 5.7E-01 5.1E-01 2.7E-01 1.2E-01 7.8E-02 4.9E-02
46 7.1E-01 6.4E-01 3.4E-01 1.5E-01 9.7E-02 6.2E-02
47 8.9E-01 8.0E-01 4.2E-01 1.9E-01 1.2E-01 7.7E-02
48 1.1E+00 9.9E-01 5.2E-01 2.3E-01 1.5E-01 9.5E-02
49 1.4E+00 1.2E+00 6.5E-01 2.9E-01 1.9E-01 1.2E-01
50 1.7E+00 1.5E+00 8.1E-01 3.6E-01 2.3E-01 1.5E-01
51 2.1E+00 1.9E+00 1.0E+00 4.5E-01 2.9E-01 1.8E-01
52 2.7E+00 2.4E+00 1.2E+00 5.6E-01 3.6E-01 2.3E-01
53 3.3E+00 3.0E+00 1.6E+00 6.9E-01 4.5E-01 2.8E-01
54 4.1E+00 3.7E+00 1.9E+00 8.6E-01 5.6E-01 3.5E-01
55 5.1E+00 4.6E+00 2.4E+00 1.1E+00 7.0E-01 4.4E-01
56 6.4E+00 5.7E+00 3.0E+00 1.3E+00 8.7E-01 5.5E-01
57 7.9E+00 7.1E+00 3.7E+00 1.7E+00 1.1E+00 6.8E-01
58 9.8E+00 8.8E+00 4.6E+00 2.1E+00 1.3E+00 8.5E-01
59 1.2E+01 1.1E+01 5.7E+00 2.6E+00 1.7E+00 1.1E+00
60 1.5E+01 1.4E+01 7.1E+00 3.2E+00 2.1E+00 1.3E+00
61 1.9E+01 1.7E+01 8.8E+00 4.0E+00 2.6E+00 1.6E+00
62 2.3E+01 2.1E+01 1.1E+01 4.9E+00 3.2E+00 2.0E+00
63 2.9E+01 2.6E+01 1.4E+01 6.1E+00 4.0E+00 2.5E+00
64 3.6E+01 3.2E+01 1.7E+01 7.6E+00 4.9E+00 3.1E+00
65 4.5E+01 4.0E+01 2.1E+01 9.4E+00 6.1E+00 3.9E+00
66 5.6E+01 5.0E+01 2.6E+01 1.2E+01 7.6E+00 4.8E+00
67 6.9E+01 6.2E+01 3.2E+01 1.4E+01 9.4E+00 5.9E+00
68 8.6E+01 7.7E+01 4.0E+01 1.8E+01 1.2E+01 7.4E+00
69 1.1E+02 9.5E+01 5.0E+01 2.2E+01 1.5E+01 9.2E+00
70 1.3E+02 1.2E+02 6.2E+01 2.8E+01 1.8E+01 1.1E+01
71 1.6E+02 1.5E+02 7.7E+01 3.4E+01 2.2E+01 1.4E+01
72 2.0E+02 1.8E+02 9.6E+01 4.3E+01 2.8E+01 1.8E+01
73 2.5E+02 2.3E+02 1.2E+02 5.3E+01 3.4E+01 2.2E+01
74 3.1E+02 2.8E+02 1.5E+02 6.6E+01 4.3E+01 2.7E+01
75 3.9E+02 3.5E+02 1.8E+02 8.2E+01 5.3E+01 3.3E+01
76 4.8E+02 4.3E+02 2.3E+02 1.0E+02 6.6E+01 4.1E+01
77 6.0E+02 5.4E+02 2.8E+02 1.3E+02 8.1E+01 5.1E+01
78 7.4E+02 6.6E+02 3.5E+02 1.6E+02 1.0E+02 6.4E+01
79 9.2E+02 8.2E+02 4.3E+02 1.9E+02 1.3E+02 7.9E+01
80 1.1E+03 1.0E+03 5.4E+02 2.4E+02 1.6E+02 9.8E+01
81 1.4E+03 1.3E+03 6.6E+02 3.0E+02 1.9E+02 1.2E+02
82 1.8E+03 1.6E+03 8.2E+02 3.7E+02 2.4E+02 1.5E+02
83 2.2E+03 1.9E+03 1.0E+03 4.6E+02 3.0E+02 1.9E+02
52
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
84 2.7E+03 2.4E+03 1.3E+03 5.7E+02 3.7E+02 2.3E+02
Table III.7. Correction coefficients C2(τ).
Time interval τ, h C
2
(τ)Time interval τ, h C
2
(τ)
1 1.65 20 1.32
2 1.62 21 1.31
3 1.59 22 1.30
4 1.57 23 1.29
5 1.54 24 1.28
6 1.52 27 1.25
7 1.50 30 1.23
8 1.48 33 1.21
9 1.47 36 1.19
10 1.45 39 1.18
11 1.43 42 1.16
12 1.42 45 1.15
13 1.40 48 1.13
14 1.39 60 1.09
15 1.38 72 1.06
16 1.36 84 1.05
17 1.35 96 1.03
18 1.34 108 1.02
19 1.33 120 1.02
The committed effective dose ݁
்௘ିଵଷ(ܶ,ܣ), Sv after acute intake of the Te-132 should be assessed
from the measured of I-132 content in the thyroid gland as:
݁
்௘ିଵଷ(ܶ,ܣ)=ܯିଵଷ(ܶ)ݖ
்௘ି ଵଷ
(ܶ,ܣ), (3.7)
where
ݖ
்௘ିଵଷ
(ܶ,ܣ)is the tabulated function given in Table III.8, Sv Bq-1.
The committed effective dose ݁(߬,ܶ,ܣ), Sv after acute intake of the mixture of radionuclides I-131,
I-132, I-133, I-134, I-135, and Te-132 should be assessed from the measured content of I-131 and
I-132 in the thyroid gland:
݁(߬,ܶ,ܣ)=݁
ିଵଷ(ܶ,ܣ)ܥ(߬
)+݁
்௘ିଵଷ(ܶ,ܣ), (3.8)
where
݁
ିଵଷ(ܶ,ܣ)is the dose assessed in accordance with Section III.4.
Table III.8. Committed effective doses from intake of Te-132 per content of the I-132 in the thyroid
gland at given time Tafter the intake (member of public, reference age groups) (ࢀࢋି ૚૜૛
(,)), Sv
per Bq.
Time after
the intake
T, days
Reference age group A
Infant 1 year 5 years 10 years 15 years Adult
0.125 2.8E-06 2.2E-06 1.2E-06 5.7E-07 3.7E-07 2.5E-07
0.25 1.3E-06 1.0E-06 5.6E-07 2.7E-07 1.8E-07 1.2E-07
0.375 1.1E-06 8.7E-07 4.6E-07 2.3E-07 1.5E-07 9.9E-08
0.5 1.0E-06 8.6E-07 4.6E-07 2.2E-07 1.4E-07 9.7E-08
0.625 1.0E-06 9.0E-07 4.7E-07 2.3E-07 1.5E-07 1.0E-07
0.75 1.1E-06 9.5E-07 5.0E-07 2.5E-07 1.6E-07 1.1E-07
53
0.875 1.2E-06 1.0E-06 5.4E-07 2.6E-07 1.7E-07 1.1E-07
1 1.2E-06 1.1E-06 5.7E-07 2.8E-07 1.8E-07 1.2E-07
1.125 1.3E-06 1.2E-06 6.1E-07 3.0E-07 1.9E-07 1.3E-07
1.25 1.4E-06 1.2E-06 6.5E-07 3.2E-07 2.0E-07 1.4E-07
1.375 1.5E-06 1.3E-06 6.9E-07 3.3E-07 2.1E-07 1.4E-07
1.5 1.5E-06 1.4E-06 7.3E-07 3.5E-07 2.3E-07 1.5E-07
1.625 1.6E-06 1.5E-06 7.7E-07 3.7E-07 2.4E-07 1.6E-07
1.75 1.7E-06 1.5E-06 8.1E-07 3.9E-07 2.5E-07 1.7E-07
1.875 1.8E-06 1.6E-06 8.5E-07 4.1E-07 2.6E-07 1.8E-07
2 1.9E-06 1.7E-06 8.9E-07 4.3E-07 2.8E-07 1.9E-07
2.25 2.1E-06 1.8E-06 9.7E-07 4.7E-07 3.0E-07 2.1E-07
2.5 2.3E-06 2.0E-06 1.1E-06 5.2E-07 3.3E-07 2.2E-07
2.75 2.4E-06 2.2E-06 1.1E-06 5.6E-07 3.6E-07 2.4E-07
3 2.6E-06 2.4E-06 1.2E-06 6.1E-07 3.9E-07 2.6E-07
3.25 2.8E-06 2.5E-06 1.3E-06 6.5E-07 4.2E-07 2.8E-07
3.5 3.1E-06 2.7E-06 1.4E-06 7.0E-07 4.5E-07 3.0E-07
3.75 3.3E-06 2.9E-06 1.5E-06 7.5E-07 4.8E-07 3.2E-07
4 3.5E-06 3.1E-06 1.6E-06 8.0E-07 5.1E-07 3.5E-07
4.25 3.7E-06 3.3E-06 1.7E-06 8.5E-07 5.5E-07 3.7E-07
4.5 4.0E-06 3.5E-06 1.9E-06 9.1E-07 5.8E-07 3.9E-07
4.75 4.2E-06 3.8E-06 2.0E-06 9.7E-07 6.2E-07 4.2E-07
5 4.5E-06 4.0E-06 2.1E-06 1.0E-06 6.6E-07 4.4E-07
5.5 5.1E-06 4.5E-06 2.4E-06 1.2E-06 7.4E-07 5.0E-07
6 5.7E-06 5.1E-06 2.7E-06 1.3E-06 8.3E-07 5.6E-07
6.5 6.4E-06 5.7E-06 3.0E-06 1.5E-06 9.4E-07 6.3E-07
7 7.2E-06 6.4E-06 3.4E-06 1.6E-06 1.1E-06 7.1E-07
7.5 8.1E-06 7.2E-06 3.8E-06 1.8E-06 1.2E-06 8.0E-07
8 9.1E-06 8.1E-06 4.3E-06 2.1E-06 1.3E-06 9.0E-07
8.5 1.0E-05 9.1E-06 4.8E-06 2.3E-06 1.5E-06 1.0E-06
9 1.1E-05 1.0E-05 5.4E-06 2.6E-06 1.7E-06 1.1E-06
9.5 1.3E-05 1.1E-05 6.0E-06 2.9E-06 1.9E-06 1.3E-06
10 1.4E-05 1.3E-05 6.7E-06 3.3E-06 2.1E-06 1.4E-06
11 1.8E-05 1.6E-05 8.5E-06 4.1E-06 2.6E-06 1.8E-06
12 2.3E-05 2.0E-05 1.1E-05 5.2E-06 3.3E-06 2.2E-06
13 2.8E-05 2.5E-05 1.3E-05 6.5E-06 4.2E-06 2.8E-06
14 3.6E-05 3.2E-05 1.7E-05 8.2E-06 5.2E-06 3.5E-06
15 4.5E-05 4.0E-05 2.1E-05 1.0E-05 6.6E-06 4.4E-06
16 5.6E-05 5.0E-05 2.6E-05 1.3E-05 8.2E-06 5.6E-06
17 7.0E-05 6.3E-05 3.3E-05 1.6E-05 1.0E-05 7.0E-06
18 8.8E-05 7.9E-05 4.1E-05 2.0E-05 1.3E-05 8.7E-06
19 1.1E-04 9.9E-05 5.2E-05 2.5E-05 1.6E-05 1.1E-05
20 1.4E-04 1.2E-04 6.5E-05 3.2E-05 2.0E-05 1.4E-05
21 1.7E-04 1.5E-04 8.1E-05 4.0E-05 2.5E-05 1.7E-05
22 2.2E-04 1.9E-04 1.0E-04 5.0E-05 3.2E-05 2.2E-05
23 2.7E-04 2.4E-04 1.3E-04 6.2E-05 4.0E-05 2.7E-05
24 3.4E-04 3.0E-04 1.6E-04 7.8E-05 5.0E-05 3.4E-05
25 4.3E-04 3.8E-04 2.0E-04 9.8E-05 6.2E-05 4.2E-05
26 5.3E-04 4.8E-04 2.5E-04 1.2E-04 7.8E-05 5.3E-05
27 6.7E-04 5.9E-04 3.1E-04 1.5E-04 9.8E-05 6.6E-05
28 8.3E-04 7.4E-04 3.9E-04 1.9E-04 1.2E-04 8.3E-05
29 1.0E-03 9.3E-04 4.9E-04 2.4E-04 1.5E-04 1.0E-04
30 1.3E-03 1.2E-03 6.1E-04 3.0E-04 1.9E-04 1.3E-04
31 1.6E-03 1.5E-03 7.6E-04 3.7E-04 2.4E-04 1.6E-04
32 2.0E-03 1.8E-03 9.5E-04 4.7E-04 3.0E-04 2.0E-04
33 2.5E-03 2.3E-03 1.2E-03 5.8E-04 3.7E-04 2.5E-04
34 3.2E-03 2.8E-03 1.5E-03 7.3E-04 4.6E-04 3.1E-04
35 4.0E-03 3.5E-03 1.9E-03 9.1E-04 5.8E-04 3.9E-04
36 4.9E-03 4.4E-03 2.3E-03 1.1E-03 7.2E-04 4.9E-04
37 6.2E-03 5.5E-03 2.9E-03 1.4E-03 9.0E-04 6.1E-04
38 7.7E-03 6.8E-03 3.6E-03 1.8E-03 1.1E-03 7.6E-04
39 9.6E-03 8.5E-03 4.5E-03 2.2E-03 1.4E-03 9.5E-04
40 1.2E-02 1.1E-02 5.6E-03 2.7E-03 1.7E-03 1.2E-03
54
41 1.5E-02 1.3E-02 7.0E-03 3.4E-03 2.2E-03 1.5E-03
42 1.9E-02 1.7E-02 8.7E-03 4.2E-03 2.7E-03 1.8E-03
43 2.3E-02 2.1E-02 1.1E-02 5.3E-03 3.4E-03 2.3E-03
44 2.9E-02 2.6E-02 1.4E-02 6.6E-03 4.2E-03 2.9E-03
45 3.6E-02 3.2E-02 1.7E-02 8.2E-03 5.3E-03 3.6E-03
46 4.5E-02 4.0E-02 2.1E-02 1.0E-02 6.5E-03 4.4E-03
47 5.6E-02 5.0E-02 2.6E-02 1.3E-02 8.1E-03 5.5E-03
48 6.9E-02 6.2E-02 3.3E-02 1.6E-02 1.0E-02 6.9E-03
49 8.6E-02 7.7E-02 4.0E-02 2.0E-02 1.3E-02 8.5E-03
50 1.1E-01 9.6E-02 5.0E-02 2.5E-02 1.6E-02 1.1E-02
51 1.3E-01 1.2E-01 6.3E-02 3.1E-02 2.0E-02 1.3E-02
52 1.7E-01 1.5E-01 7.8E-02 3.8E-02 2.4E-02 1.6E-02
53 2.1E-01 1.8E-01 9.7E-02 4.7E-02 3.0E-02 2.0E-02
54 2.6E-01 2.3E-01 1.2E-01 5.9E-02 3.8E-02 2.5E-02
55 3.2E-01 2.8E-01 1.5E-01 7.3E-02 4.7E-02 3.2E-02
56 4.0E-01 3.5E-01 1.9E-01 9.1E-02 5.8E-02 3.9E-02
57 4.9E-01 4.4E-01 2.3E-01 1.1E-01 7.2E-02 4.9E-02
58 6.1E-01 5.5E-01 2.9E-01 1.4E-01 9.0E-02 6.1E-02
59 7.6E-01 6.8E-01 3.6E-01 1.7E-01 1.1E-01 7.5E-02
60 9.5E-01 8.4E-01 4.4E-01 2.2E-01 1.4E-01 9.4E-02
61 1.2E+00 1.0E+00 5.5E-01 2.7E-01 1.7E-01 1.2E-01
62 1.5E+00 1.3E+00 6.9E-01 3.3E-01 2.1E-01 1.4E-01
63 1.8E+00 1.6E+00 8.5E-01 4.2E-01 2.7E-01 1.8E-01
64 2.3E+00 2.0E+00 1.1E+00 5.2E-01 3.3E-01 2.2E-01
65 2.8E+00 2.5E+00 1.3E+00 6.4E-01 4.1E-01 2.8E-01
66 3.5E+00 3.1E+00 1.6E+00 8.0E-01 5.1E-01 3.4E-01
67 4.3E+00 3.8E+00 2.0E+00 9.9E-01 6.3E-01 4.3E-01
68 5.4E+00 4.8E+00 2.5E+00 1.2E+00 7.9E-01 5.3E-01
69 6.7E+00 5.9E+00 3.1E+00 1.5E+00 9.7E-01 6.6E-01
70 8.3E+00 7.4E+00 3.9E+00 1.9E+00 1.2E+00 8.2E-01
71 1.0E+01 9.1E+00 4.8E+00 2.3E+00 1.5E+00 1.0E+00
72 1.3E+01 1.1E+01 6.0E+00 2.9E+00 1.9E+00 1.3E+00
73 1.6E+01 1.4E+01 7.4E+00 3.6E+00 2.3E+00 1.6E+00
74 2.0E+01 1.7E+01 9.2E+00 4.5E+00 2.9E+00 1.9E+00
75 2.4E+01 2.2E+01 1.1E+01 5.6E+00 3.6E+00 2.4E+00
76 3.0E+01 2.7E+01 1.4E+01 6.9E+00 4.4E+00 3.0E+00
77 3.7E+01 3.3E+01 1.8E+01 8.6E+00 5.5E+00 3.7E+00
78 4.6E+01 4.1E+01 2.2E+01 1.1E+01 6.8E+00 4.6E+00
79 5.7E+01 5.1E+01 2.7E+01 1.3E+01 8.4E+00 5.7E+00
80 7.1E+01 6.4E+01 3.3E+01 1.6E+01 1.0E+01 7.1E+00
81 8.8E+01 7.9E+01 4.2E+01 2.0E+01 1.3E+01 8.8E+00
82 1.1E+02 9.8E+01 5.1E+01 2.5E+01 1.6E+01 1.1E+01
83 1.4E+02 1.2E+02 6.4E+01 3.1E+01 2.0E+01 1.3E+01
84 1.7E+02 1.5E+02 7.9E+01 3.9E+01 2.5E+01 1.7E+01
III.7 Dose to the foetal thyroid gland estimated based on the I-131 content in
the maternal thyroid gland
The committed absorbed dose ܦିଵଷ
,்௛
ܶ,ܣ
, Gy to the foetal thyroid gland at term after acute
intake of I-131 by the mother should be estimated as:
ܦିଵଷ
,
ܶ,ܣ=ܯିଵଷ(ܶ)ݖ
ିଵଷ
,்௛ (ܶ,ܣ), (3.9)
where
ܯିଵଷ(ܶ)is the measured I-131 content in the maternal thyroid gland at the time Tafter the intake,
Bq;
ݖ
ିଵଷ
,்௛ (ܶ,ܣ)is the tabulated function given in Table III.9, Gy Bq-1.
55
The committed absorbed dose Df, Th(τ, T, Af), Gy to the foetal thyroid gland at term after acute intake
by the mother of the reference mixture of I-131, I-132, I-133, I-134, I-135, and Te-132 should be
estimated as:
ܦ,
߬,ܶ,ܣ=ܦି ଵଷଵ
,்௛
ܶ,ܣܥ(߬), (3.10)
where
ܦିଵଷଵ
,்௛ ܶ,ܣis the dose assessed with the equation (3.9).
C1(τ) is the correction coefficient for the time τafter the reactor shutdown (Table III.5).
Table III.9. Committed absorbed dose to the foetal thyroid gland at term from intake of I-131 per
content of I-131 in the maternal thyroid gland at the time Tafter the intake. For the gestational
age group Af(ି ૚૜૚
,(,)), Gy per Bq.
Time after
the intake,
days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
0.125 6.9E-10 1.3E-09 1.5E-08 1.1E-06 3.0E-06 5.0E-06
0.25 4.7E-10 8.9E-10 1.1E-08 7.9E-07 2.2E-06 3.7E-06
0.375 3.9E-10 7.5E-10 9.4E-09 6.9E-07 1.9E-06 3.2E-06
0.5 3.5E-10 6.9E-10 8.7E-09 6.5E-07 1.8E-06 3.1E-06
0.625 3.3E-10 6.6E-10 8.4E-09 6.3E-07 1.8E-06 3.0E-06
0.75 3.2E-10 6.4E-10 8.3E-09 6.3E-07 1.8E-06 3.0E-06
0.875 3.2E-10 6.4E-10 8.2E-09 6.3E-07 1.8E-06 3.0E-06
1 3.2E-10 6.4E-10 8.3E-09 6.4E-07 1.8E-06 3.0E-06
1.125 3.2E-10 6.4E-10 8.4E-09 6.4E-07 1.8E-06 3.0E-06
1.25 3.2E-10 6.4E-10 8.4E-09 6.5E-07 1.8E-06 3.1E-06
1.375 3.2E-10 6.5E-10 8.6E-09 6.6E-07 1.9E-06 3.1E-06
1.5 3.3E-10 6.6E-10 8.7E-09 6.7E-07 1.9E-06 3.1E-06
1.625 3.3E-10 6.7E-10 8.8E-09 6.8E-07 1.9E-06 3.2E-06
1.75 3.4E-10 6.8E-10 8.9E-09 6.9E-07 1.9E-06 3.2E-06
1.875 3.5E-10 6.9E-10 9.0E-09 7.0E-07 2.0E-06 3.3E-06
2 3.5E-10 7.0E-10 9.2E-09 7.1E-07 2.0E-06 3.3E-06
2.25 3.6E-10 7.1E-10 9.4E-09 7.3E-07 2.0E-06 3.4E-06
2.5 3.7E-10 7.3E-10 9.7E-09 7.5E-07 2.1E-06 3.5E-06
2.75 3.8E-10 7.5E-10 9.9E-09 7.7E-07 2.2E-06 3.6E-06
3 3.9E-10 7.7E-10 1.0E-08 7.9E-07 2.2E-06 3.7E-06
3.25 4.1E-10 7.9E-10 1.0E-08 8.1E-07 2.3E-06 3.8E-06
3.5 4.2E-10 8.1E-10 1.1E-08 8.3E-07 2.3E-06 3.9E-06
3.75 4.3E-10 8.3E-10 1.1E-08 8.5E-07 2.4E-06 4.0E-06
4 4.4E-10 8.5E-10 1.1E-08 8.7E-07 2.4E-06 4.1E-06
4.25 4.5E-10 8.8E-10 1.2E-08 8.9E-07 2.5E-06 4.2E-06
4.5 4.6E-10 9.0E-10 1.2E-08 9.1E-07 2.6E-06 4.3E-06
4.75 4.7E-10 9.2E-10 1.2E-08 9.4E-07 2.6E-06 4.4E-06
5 4.8E-10 9.4E-10 1.2E-08 9.6E-07 2.7E-06 4.5E-06
5.5 5.1E-10 9.9E-10 1.3E-08 1.0E-06 2.8E-06 4.7E-06
6 5.3E-10 1.0E-09 1.4E-08 1.1E-06 3.0E-06 4.9E-06
6.5 5.6E-10 1.1E-09 1.4E-08 1.1E-06 3.1E-06 5.2E-06
7 5.8E-10 1.1E-09 1.5E-08 1.2E-06 3.3E-06 5.5E-06
7.5 6.1E-10 1.2E-09 1.6E-08 1.2E-06 3.4E-06 5.7E-06
8 6.4E-10 1.3E-09 1.7E-08 1.3E-06 3.6E-06 6.0E-06
8.5 6.7E-10 1.3E-09 1.8E-08 1.4E-06 3.8E-06 6.3E-06
9 7.0E-10 1.4E-09 1.8E-08 1.4E-06 4.0E-06 6.6E-06
9.5 7.4E-10 1.5E-09 1.9E-08 1.5E-06 4.2E-06 7.0E-06
10 7.7E-10 1.5E-09 2.0E-08 1.6E-06 4.4E-06 7.3E-06
11 8.5E-10 1.7E-09 2.2E-08 1.7E-06 4.8E-06 8.0E-06
12 9.4E-10 1.9E-09 2.5E-08 1.9E-06 5.3E-06 8.8E-06
13 1.0E-09 2.1E-09 2.7E-08 2.1E-06 5.9E-06 9.7E-06
14 1.1E-09 2.3E-09 3.0E-08 2.3E-06 6.5E-06 1.1E-05
15 1.2E-09 2.5E-09 3.3E-08 2.5E-06 7.1E-06 1.2E-05
56
Time after
the intake,
days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
16 1.4E-09 2.8E-09 3.6E-08 2.8E-06 7.8E-06 1.3E-05
17 1.5E-09 3.0E-09 4.0E-08 3.1E-06 8.6E-06 1.4E-05
18 1.7E-09 3.3E-09 4.4E-08 3.4E-06 9.5E-06 1.6E-05
19 1.8E-09 3.7E-09 4.8E-08 3.7E-06 1.0E-05 1.7E-05
20 2.0E-09 4.1E-09 5.3E-08 4.1E-06 1.2E-05 1.9E-05
21 2.2E-09 4.5E-09 5.9E-08 4.5E-06 1.3E-05 2.1E-05
22 2.5E-09 4.9E-09 6.5E-08 5.0E-06 1.4E-05
23 2.7E-09 5.4E-09 7.1E-08 5.5E-06 1.5E-05
24 3.0E-09 6.0E-09 7.8E-08 6.1E-06 1.7E-05
25 3.3E-09 6.6E-09 8.6E-08 6.7E-06 1.9E-05
26 3.6E-09 7.2E-09 9.5E-08 7.3E-06 2.0E-05
27 4.0E-09 8.0E-09 1.0E-07 8.1E-06 2.3E-05
28 4.4E-09 8.8E-09 1.1E-07 8.9E-06 2.5E-05
29 4.8E-09 9.6E-09 1.3E-07 9.8E-06 2.7E-05
30 5.3E-09 1.1E-08 1.4E-07 1.1E-05 3.0E-05
31 5.8E-09 1.2E-08 1.5E-07 1.2E-05 3.3E-05
32 6.4E-09 1.3E-08 1.7E-07 1.3E-05 3.6E-05
33 7.1E-09 1.4E-08 1.9E-07 1.4E-05 4.0E-05
34 7.8E-09 1.6E-08 2.0E-07 1.6E-05 4.4E-05
35 8.5E-09 1.7E-08 2.2E-07 1.7E-05 4.8E-05
36 9.4E-09 1.9E-08 2.5E-07 1.9E-05 5.3E-05
37 1.0E-08 2.1E-08 2.7E-07 2.1E-05 5.8E-05
38 1.1E-08 2.3E-08 3.0E-07 2.3E-05 6.4E-05
39 1.3E-08 2.5E-08 3.3E-07 2.5E-05 7.0E-05
40 1.4E-08 2.7E-08 3.6E-07 2.8E-05 7.7E-05
41 1.5E-08 3.0E-08 4.0E-07 3.1E-05 8.5E-05
42 1.7E-08 3.3E-08 4.4E-07 3.4E-05 9.4E-05
43 1.8E-08 3.6E-08 4.8E-07 3.7E-05 1.0E-04
44 2.0E-08 4.0E-08 5.3E-07 4.1E-05 1.1E-04
45 2.2E-08 4.4E-08 5.8E-07 4.5E-05 1.2E-04
46 2.4E-08 4.8E-08 6.4E-07 4.9E-05 1.4E-04
47 2.7E-08 5.3E-08 7.0E-07 5.4E-05 1.5E-04
48 2.9E-08 5.9E-08 7.7E-07 5.9E-05 1.6E-04
49 3.2E-08 6.4E-08 8.5E-07 6.5E-05 1.8E-04
50 3.6E-08 7.1E-08 9.3E-07 7.2E-05 2.0E-04
51 3.9E-08 7.8E-08 1.0E-06 7.9E-05 2.2E-04
52 4.3E-08 8.5E-08 1.1E-06 8.7E-05 2.4E-04
53 4.7E-08 9.4E-08 1.2E-06 9.5E-05 2.6E-04
54 5.2E-08 1.0E-07 1.4E-06 1.0E-04 2.9E-04
55 5.7E-08 1.1E-07 1.5E-06 1.2E-04 3.2E-04
56 6.3E-08 1.2E-07 1.6E-06 1.3E-04 3.5E-04
57 6.9E-08 1.4E-07 1.8E-06 1.4E-04 3.9E-04
58 7.6E-08 1.5E-07 2.0E-06 1.5E-04 4.2E-04
59 8.3E-08 1.7E-07 2.2E-06 1.7E-04 4.7E-04
60 9.2E-08 1.8E-07 2.4E-06 1.8E-04 5.1E-04
61 1.0E-07 2.0E-07 2.6E-06 2.0E-04 5.6E-04
62 1.1E-07 2.2E-07 2.9E-06 2.2E-04 6.2E-04
63 1.2E-07 2.4E-07 3.2E-06 2.5E-04 6.8E-04
64 1.3E-07 2.7E-07 3.5E-06 2.7E-04 7.5E-04
65 1.5E-07 2.9E-07 3.8E-06 3.0E-04 8.2E-04
66 1.6E-07 3.2E-07 4.2E-06 3.3E-04 9.0E-04
67 1.8E-07 3.5E-07 4.6E-06 3.6E-04 9.9E-04
68 2.0E-07 3.9E-07 5.1E-06 3.9E-04 1.1E-03
69 2.1E-07 4.2E-07 5.6E-06 4.3E-04 1.2E-03
70 2.4E-07 4.7E-07 6.2E-06 4.7E-04 1.3E-03
71 2.6E-07 5.1E-07 6.8E-06 5.2E-04 1.4E-03
72 2.8E-07 5.6E-07 7.4E-06 5.7E-04 1.6E-03
73 3.1E-07 6.2E-07 8.2E-06 6.3E-04 1.7E-03
74 3.4E-07 6.8E-07 9.0E-06 6.9E-04 1.9E-03
57
Time after
the intake,
days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
75 3.8E-07 7.5E-07 9.9E-06 7.6E-04 2.1E-03
76 4.1E-07 8.2E-07 1.1E-05 8.3E-04 2.3E-03
77 4.6E-07 9.0E-07 1.2E-05 9.2E-04 2.5E-03
78 5.0E-07 9.9E-07 1.3E-05 1.0E-03 2.8E-03
79 5.5E-07 1.1E-06 1.4E-05 1.1E-03 3.1E-03
80 6.0E-07 1.2E-06 1.6E-05 1.2E-03 3.4E-03
81 6.6E-07 1.3E-06 1.7E-05 1.3E-03 3.7E-03
82 7.3E-07 1.4E-06 1.9E-05 1.5E-03 4.1E-03
83 8.0E-07 1.6E-06 2.1E-05 1.6E-03 4.5E-03
84 8.8E-07 1.7E-06 2.3E-05 1.8E-03 4.9E-03
85 9.7E-07 1.9E-06 2.5E-05 1.9E-03 5.4E-03
86 1.1E-06 2.1E-06 2.8E-05 2.1E-03 5.9E-03
87 1.2E-06 2.3E-06 3.1E-05 2.3E-03 6.5E-03
88 1.3E-06 2.5E-06 3.4E-05 2.6E-03 7.1E-03
89 1.4E-06 2.8E-06 3.7E-05 2.8E-03 7.9E-03
90 1.5E-06 3.1E-06 4.0E-05 3.1E-03 8.6E-03
91 1.7E-06 3.4E-06 4.4E-05 3.4E-03 9.5E-03
92 1.9E-06 3.7E-06 4.9E-05 3.8E-03
93 2.1E-06 4.1E-06 5.4E-05 4.1E-03
94 2.3E-06 4.5E-06 5.9E-05 4.5E-03
95 2.5E-06 4.9E-06 6.5E-05 5.0E-03
96 2.7E-06 5.4E-06 7.1E-05 5.5E-03
97 3.0E-06 5.9E-06 7.8E-05 6.0E-03
98 3.3E-06 6.5E-06 8.6E-05 6.6E-03
99 3.6E-06 7.2E-06 9.4E-05 7.3E-03
100 4.0E-06 7.9E-06 1.0E-04 8.0E-03
58
III.8 Doses to the foetal thyroid gland estimated based on the I-131 and I-132
content in the maternal thyroid gland
The committed absorbed dose ܦ்௘ିଵଷ
,்௛
ܶ,ܣ
, Gy to the foetal thyroid gland at term after acute
intake of the Te-132 should be assessed from the measured I-132 content in the maternal thyroid
gland as:
ܦ்௘ିଵଷ
,
ܶ,ܣ=ܯିଵଷ(ܶ)ݖ
்௘ିଵଷ
,்௛ (ܶ,ܣ), (3.11)
where
ܯିଵଷ(ܶ)is the measured I-132 content in the maternal thyroid gland at the time Tafter the intake,
Bq;
ݖ
்௘ିଵଷ
,்௛ (ܶ,ܣ)is the tabulated function given in where
ܦܫ
−131݂,ܶܶ,ܣ݂
is the dose assessed with the equation (3.9);
C2(τ) is the correction coefficient for the time τafter the reactor shutdown (Table III.7).
Table III.10, Gy Bq-1.
The committed absorbed dose ܦ,்௛
߬,ܶ,ܣ
, Gy to the foetal thyroid gland at term after acute
intake of the mixture of radionuclides I-131, I-132, I-133, I-134, I-135, and Te-132 by the mother
should be assessed as:
ܦ,
߬,ܶ,ܣ=ܦି ଵଷଵ
,்௛
ܶ,ܣܥ(߬
)+ܦ்௘ିଵଷ
,்௛
ܶ,ܣ
, (3.12)
where
ܦିଵଷ
,்௛
ܶ,ܣis the dose assessed with the equation (3.9);
C2(τ) is the correction coefficient for the time τafter the reactor shutdown (Table III.7).
Table III.10. Committed absorbed dose at term to the foetal thyroid gland from intake of Te-132
per content of I-132 in the maternal thyroid gland at the time Tafter the intake. For gestational
age group Af(ࢀࢋି૚૜૛
,(,)), Gy per Bq.
Time after the
intake, days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
0.125 2.7E-08 1.6E-08 3.7E-08 8.9E-07 2.4E-06 4.2E-06
0.25 1.5E-08 9.0E-09 2.2E-08 5.3E-07 1.4E-06 2.5E-06
0.375 1.3E-08 7.9E-09 1.9E-08 4.7E-07 1.3E-06 2.2E-06
0.5 1.3E-08 7.9E-09 1.9E-08 4.7E-07 1.3E-06 2.2E-06
0.625 1.4E-08 8.3E-09 2.0E-08 5.0E-07 1.4E-06 2.4E-06
0.75 1.5E-08 8.8E-09 2.1E-08 5.3E-07 1.5E-06 2.5E-06
0.875 1.6E-08 9.4E-09 2.3E-08 5.7E-07 1.5E-06 2.7E-06
1 1.7E-08 1.0E-08 2.4E-08 6.1E-07 1.7E-06 2.9E-06
1.125 1.8E-08 1.1E-08 2.6E-08 6.5E-07 1.8E-06 3.1E-06
1.25 1.9E-08 1.1E-08 2.8E-08 6.9E-07 1.9E-06 3.3E-06
1.375 2.0E-08 1.2E-08 2.9E-08 7.3E-07 2.0E-06 3.5E-06
1.5 2.1E-08 1.3E-08 3.1E-08 7.7E-07 2.1E-06 3.7E-06
1.625 2.2E-08 1.3E-08 3.3E-08 8.2E-07 2.2E-06 3.9E-06
1.75 2.3E-08 1.4E-08 3.5E-08 8.6E-07 2.3E-06 4.1E-06
1.875 2.4E-08 1.5E-08 3.6E-08 9.0E-07 2.5E-06 4.3E-06
2 2.5E-08 1.6E-08 3.8E-08 9.5E-07 2.6E-06 4.5E-06
2.25 2.7E-08 1.7E-08 4.2E-08 1.0E-06 2.8E-06 4.9E-06
2.5 3.0E-08 1.9E-08 4.6E-08 1.1E-06 3.1E-06 5.4E-06
2.75 3.2E-08 2.0E-08 5.0E-08 1.2E-06 3.4E-06 5.9E-06
3 3.4E-08 2.2E-08 5.4E-08 1.3E-06 3.6E-06 6.3E-06
59
Time after the
intake, days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
3.25 3.7E-08 2.4E-08 5.8E-08 1.4E-06 3.9E-06 6.8E-06
3.5 3.9E-08 2.5E-08 6.2E-08 1.5E-06 4.2E-06 7.3E-06
3.75 4.2E-08 2.7E-08 6.6E-08 1.7E-06 4.5E-06 7.9E-06
4 4.5E-08 2.9E-08 7.1E-08 1.8E-06 4.8E-06 8.4E-06
4.25 4.7E-08 3.1E-08 7.5E-08 1.9E-06 5.1E-06 9.0E-06
4.5 5.0E-08 3.3E-08 8.0E-08 2.0E-06 5.5E-06 9.6E-06
4.75 5.3E-08 3.5E-08 8.5E-08 2.1E-06 5.8E-06 1.0E-05
5 5.6E-08 3.7E-08 9.1E-08 2.3E-06 6.2E-06 1.1E-05
5.5 6.2E-08 4.2E-08 1.0E-07 2.6E-06 7.0E-06 1.2E-05
6 7.0E-08 4.7E-08 1.2E-07 2.9E-06 7.9E-06 1.4E-05
6.5 7.7E-08 5.3E-08 1.3E-07 3.2E-06 8.8E-06 1.6E-05
7 8.6E-08 5.9E-08 1.4E-07 3.6E-06 9.9E-06 1.7E-05
7.5 9.5E-08 6.7E-08 1.6E-07 4.1E-06 1.1E-05 2.0E-05
8 1.1E-07 7.5E-08 1.8E-07 4.6E-06 1.3E-05 2.2E-05
8.5 1.2E-07 8.4E-08 2.0E-07 5.1E-06 1.4E-05 2.5E-05
9 1.3E-07 9.4E-08 2.3E-07 5.7E-06 1.6E-05 2.8E-05
9.5 1.4E-07 1.0E-07 2.6E-07 6.4E-06 1.8E-05 3.1E-05
10 1.6E-07 1.2E-07 2.9E-07 7.2E-06 2.0E-05 3.5E-05
11 2.0E-07 1.5E-07 3.6E-07 9.0E-06 2.5E-05 4.4E-05
12 2.4E-07 1.8E-07 4.5E-07 1.1E-05 3.1E-05 5.5E-05
13 3.0E-07 2.3E-07 5.6E-07 1.4E-05 3.9E-05 6.9E-05
14 3.7E-07 2.9E-07 7.1E-07 1.8E-05 4.9E-05 8.7E-05
15 4.6E-07 3.6E-07 8.8E-07 2.2E-05 6.2E-05 1.1E-04
16 5.6E-07 4.5E-07 1.1E-06 2.8E-05 7.7E-05 1.4E-04
17 7.0E-07 5.6E-07 1.4E-06 3.5E-05 9.7E-05 1.7E-04
18 8.6E-07 7.0E-07 1.7E-06 4.4E-05 1.2E-04 2.2E-04
19 1.1E-06 8.8E-07 2.2E-06 5.5E-05 1.5E-04 2.7E-04
20 1.3E-06 1.1E-06 2.7E-06 6.9E-05 1.9E-04 3.4E-04
21 1.6E-06 1.4E-06 3.4E-06 8.6E-05 2.4E-04 4.3E-04
22 2.0E-06 1.7E-06 4.2E-06 1.1E-04 3.0E-04
23 2.5E-06 2.1E-06 5.3E-06 1.3E-04 3.7E-04
24 3.1E-06 2.7E-06 6.6E-06 1.7E-04 4.7E-04
25 3.9E-06 3.3E-06 8.3E-06 2.1E-04 5.8E-04
26 4.8E-06 4.2E-06 1.0E-05 2.6E-04 7.3E-04
27 6.0E-06 5.2E-06 1.3E-05 3.3E-04 9.1E-04
28 7.5E-06 6.5E-06 1.6E-05 4.1E-04 1.1E-03
29 9.4E-06 8.1E-06 2.0E-05 5.1E-04 1.4E-03
30 1.2E-05 1.0E-05 2.5E-05 6.4E-04 1.8E-03
31 1.5E-05 1.3E-05 3.1E-05 8.0E-04 2.2E-03
32 1.8E-05 1.6E-05 3.9E-05 9.9E-04 2.8E-03
33 2.3E-05 1.9E-05 4.9E-05 1.2E-03 3.5E-03
34 2.8E-05 2.4E-05 6.1E-05 1.5E-03 4.3E-03
35 3.5E-05 3.0E-05 7.6E-05 1.9E-03 5.4E-03
36 4.3E-05 3.7E-05 9.5E-05 2.4E-03 6.8E-03
37 5.4E-05 4.7E-05 1.2E-04 3.0E-03 8.4E-03
38 6.7E-05 5.8E-05 1.5E-04 3.7E-03 1.1E-02
39 8.3E-05 7.2E-05 1.8E-04 4.6E-03 1.3E-02
40 1.0E-04 9.0E-05 2.3E-04 5.8E-03 1.6E-02
41 1.3E-04 1.1E-04 2.8E-04 7.2E-03 2.0E-02
42 1.6E-04 1.4E-04 3.5E-04 9.0E-03 2.5E-02
43 2.0E-04 1.7E-04 4.4E-04 1.1E-02 3.2E-02
44 2.5E-04 2.1E-04 5.5E-04 1.4E-02 3.9E-02
45 3.1E-04 2.7E-04 6.8E-04 1.7E-02 4.9E-02
46 3.8E-04 3.3E-04 8.5E-04 2.2E-02 6.1E-02
47 4.7E-04 4.1E-04 1.1E-03 2.7E-02 7.6E-02
48 5.9E-04 5.1E-04 1.3E-03 3.3E-02 9.5E-02
49 7.3E-04 6.3E-04 1.6E-03 4.1E-02 1.2E-01
50 9.0E-04 7.9E-04 2.0E-03 5.1E-02 1.5E-01
51 1.1E-03 9.8E-04 2.5E-03 6.4E-02 1.8E-01
52 1.4E-03 1.2E-03 3.1E-03 8.0E-02 2.3E-01
60
Time after the
intake, days
Reference gestational age group A
f
Conception 5 weeks 10 weeks 15 weeks 25 weeks 35 weeks
53 1.7E-03 1.5E-03 3.9E-03 9.9E-02 2.8E-01
54 2.1E-03 1.9E-03 4.8E-03 1.2E-01 3.5E-01
55 2.7E-03 2.3E-03 6.0E-03 1.5E-01 4.4E-01
56 3.3E-03 2.9E-03 7.5E-03 1.9E-01 5.5E-01
57 4.1E-03 3.6E-03 9.3E-03 2.4E-01 6.8E-01
58 5.1E-03 4.5E-03 1.2E-02 2.9E-01 8.5E-01
59 6.3E-03 5.5E-03 1.4E-02 3.6E-01 1.1E+00
60 7.8E-03 6.9E-03 1.8E-02 4.5E-01 1.3E+00
61 9.6E-03 8.5E-03 2.2E-02 5.6E-01 1.6E+00
62 1.2E-02 1.1E-02 2.7E-02 7.0E-01 2.0E+00
63 1.5E-02 1.3E-02 3.4E-02 8.7E-01 2.5E+00
64 1.8E-02 1.6E-02 4.2E-02 1.1E+00 3.1E+00
65 2.3E-02 2.0E-02 5.2E-02 1.3E+00 3.9E+00
66 2.8E-02 2.5E-02 6.5E-02 1.7E+00 4.9E+00
67 3.5E-02 3.1E-02 8.0E-02 2.1E+00 6.0E+00
68 4.3E-02 3.9E-02 1.0E-01 2.6E+00 7.5E+00
69 5.3E-02 4.8E-02 1.2E-01 3.2E+00 9.3E+00
70 6.6E-02 5.9E-02 1.5E-01 3.9E+00 1.2E+01
71 8.2E-02 7.4E-02 1.9E-01 4.9E+00 1.4E+01
72 1.0E-01 9.1E-02 2.4E-01 6.0E+00 1.8E+01
73 1.3E-01 1.1E-01 2.9E-01 7.5E+00 2.2E+01
74 1.6E-01 1.4E-01 3.6E-01 9.3E+00 2.8E+01
75 1.9E-01 1.7E-01 4.5E-01 1.2E+01 3.4E+01
76 2.4E-01 2.2E-01 5.6E-01 1.4E+01 4.3E+01
77 2.9E-01 2.7E-01 6.9E-01 1.8E+01 5.3E+01
78 3.6E-01 3.3E-01 8.5E-01 2.2E+01 6.6E+01
79 4.5E-01 4.1E-01 1.1E+00 2.7E+01 8.2E+01
80 5.6E-01 5.1E-01 1.3E+00 3.4E+01 1.0E+02
81 6.9E-01 6.3E-01 1.6E+00 4.2E+01 1.3E+02
82 8.5E-01 7.8E-01 2.0E+00 5.2E+01 1.6E+02
83 1.1E+00 9.6E-01 2.5E+00 6.5E+01 1.9E+02
84 1.3E+00 1.2E+00 3.1E+00 8.0E+01 2.4E+02
III.9 Scope of applicability
III.9.1 Quantities used in this section
The committed absorbed dose ݀()in the thyroid, is defined as the time integral of the absorbed
dose rate ்݀̇௛() in the thyroid over time Δ after the intake of the radioactive isotopes of iodine or
tellurium, and is given by:
݀
(
)
=
݀
̇
(
)
(
t
)
݀ݐ
, (3.13)
where
t0is the time of intake;
Δis the period of integration, also called the period of commitment;
்݀̇௛()(ݐ)is the absorbed dose rate in the thyroid, at time tafter the intake of a radionuclide of
concern.
III.9.2 Ranges of parameter values describing the conditions of exposure
Values of thyroid dose per content functions provided in this section for measured I-131 activity
content in the thyroid gland are applicable for the following parameter values and their ranges:
61
Path of intake: inhalation of aerosols or gases;
AMTD/AMAD of aerosol: 0.001 - 20 µm;
Type of material: aerosols Type F, methyl iodide, elemental iodine, tellurium gas or vapour;
Age of an individual: all ages of the member of public [ICRP, 1989], including children; all
reference embryo and foetus gestational ages [ICRP, 2001];
Euthyroid status of an individual, reference ICRP biokinetic parameter values and reference
ICRP organ masses [ICRP, 1989, 1994, 2001];
Time interval between the time of intake and the time of measurement:
oFor estimations of the dose from I-131 based on the measurement of the I-131
content in the thyroid gland: 1 – 100 days; data provided for the first 24 hours after
the intake should be used as indicative values associated with large uncertainties;
oFor estimations of the dose from Te-132 based on the measurements of I-132
contents in the thyroid gland: 1 – 84 days; data provided for the first 24 hours after
the intake should be used as indicative values associated with large uncertainties;
oFor estimations of the I-131 thyroid dose in case of thyroid blocking before exposure:
the first measurement is after 3 days since the intake, otherwise see sections III.9.3,
III.9.4 and Appendix B;
For application of correction coefficients, which account doses from other short-lived radio-
iodine isotopes and Te-132:
oEarly stages of a nuclear emergency at a light water power reactor (LWR);
oTime interval τbetween the time of reactor shutdown and the time of intake: 1 - 120
hours.
Thyroid blocking: the methods and dose coefficients given here are applicable for
assessments of I-131 thyroid doses with the time restriction stated above, otherwise
recommendations from sections III.9.3, III.9.4 and Appendix B should be used. However,
these methods and coefficients are not applicable for estimations of the thyroid exposure to
other radioactive isotopes, or for estimations of the effective dose.
Table III.11 describes the inventory of iodine and tellurium radioisotopes in the core of a light water
reactor (LWR) which was used in the derivation of the correction coefficients in sections III.5 and III.6.
A conservative assumption on the equality of release fractions of halogens and tellurium was used
for both in-containment and environmental source terms. Table III.12 provides additional
information about the emergency event timings and the phase-specific core activity release fractions
for PWR/BWR. If additional information about the mechanism of the release is available, data from
Table III.12 can be used for improvement of the reliability of assessments of the thyroid absorbed
dose associated with Te-132 and its progeny I-132. For example, Table III.12 indicates that in case of
a gap release to the containment and an early failure of the containment, the level of Te-132 in the
initial environmental source term will be small and the contribution of Te-132 and its progeny I-132
to the thyroid dose can be neglected.
62
Table III.11. Typical inventory of iodine and tellurium radioisotopes in the core of a light water
reactor (LWR) [USNRC, 1995].
Radionuclide Half-life λr, d-1
Generic
LWR core
inventory6,
Bq·MWt-1
Ratio at
shutdown,
“reference
mixture”
I-131 8.0252 d 0.086 9.88E+14 1.00
I-132 2.295 h 7.25 1.44E+15 1.46
I-133 20.8 h 0.8 2.01E+15 2.03
I-134 52.5 m 19 2.21E+15 2.24
I-135 6.58 h 2.53 1.92E+15 1.94
Te-132 3.204 d 0.216 1.41E+15 1.43
Table III.12. In-containment source term: event timings and phase-specific core activity release
fractions for PWR/BWR [USNRC, 1995].
Nuclide Group Cladding Failure
(Gap Release
Phase)
0.5-hour
duration
Core Melt Phase
(In-Vessel Phase)
1.3/1.5-hour
duration
Post vessel
Melt-Though
Phase
(Ex-Vessel
Phase)
2.0/3.0-hour
duration
Halogens (I, Br) 0.05 0.35/0.25 0.25/0.30
Tellurium Group
(Te, Sb, Se)
0 0.05 0.25
III.9.3 Thyroid blocking
It cannot be excluded that, despite administering stable iodine, a positive thyroid measurement may
occur if: (i) there has been a high intake or (ii) the administration of stable iodine was either too early
or too late. In the cases of thyroid blocking before exposure, the dose per content functions for I-131
(Table III.3) and the methods for assessment of thyroid exposure to I-131 (Section III.3) given in these
guidelines are still valid, but with an additional condition that the measurement of the thyroid
activity content is performed after the 3rd day since the intake of radio-iodine. Material from the
Scientific Report of CAThyMARA Work Package 6 [Vrba et al. 2017] demonstrates that in such a case
an extra error in the estimated thyroid absorbed will not exceed 20%. If the time limitation indicated
above cannot be met, it is recommended to apply a multiplication correction coefficient from Table
III.13 to the I-131 thyroid dose estimate obtained with methods provided in these guidelines. In case
of high dose estimates, see Section III.9.4.
If thyroid blocking occurs after exposure, the dose per content functions for I-131 and methods for
assessment of thyroid exposure to I-131 provided in these guidelines are valid, except for very early
measurements (less than 6 hours after intake, see [Vrba et al. 2017]).
6Estimates are based on a single fuel assembly with a burnup of 38,585 megawatt-days per metric ton of
uranium. The enrichment of the assembly is 4.0 mass percent of uranium-235. The generic core contained
193 assemblies and had a power level of 3,479 megawatts thermal (MWt). Normalisation was done by
multiplying the calculated inventory for a single assembly by 193 assemblies per core and then dividing by
3,479 MWt [USNRC, 2012].
63
Table III.13. Correction coefficients estimated with the three-compartmental model [Zanzonico,
2000] for the correction of values for committed absorbed dose to the thyroid integrated over 30
days (see Table III.3) in the case of administration of stable iodine before exposure to radioactive
iodine.
Time interval between the administration of stable iodine
and exposure (intake) to radioactive iodine, hours
Time interval between
the exposure (intake)
and the measurement,
hours
0 – 12 12 – 24 24 – 36 > 36
0-6 22 16 12 8
>6 – 12 16 12 8.5 6
>12 - 24 11 8 6 4
>24 – 36 6 4.5 3.5 2.5
>36 – 48 4 2.5 2 1.5
>48 – 60 2.5 2 1.3 1
>60 – 72 1.5 1.2 0.9 0.9
III.9.4 High dose estimates
If the thyroid dose or committed effective dose exceeds a given threshold above which health
concern is expected, it is recommended to refine the initial dose evaluation as follows:
IAEA [IAEA, 2013] considers that a thyroid equivalent dose greater than 100 mSv is of health concern.
Therefore, if the application of the dose assessment methods results in thyroid absorbed dose
estimates exceeding a value of about 0.1 Gy, it is recommended to:
Verify the validity of input parameter values used;
Initiate an individual follow-up thyroid monitoring programme that should include:
oMany thyroid measurements over several weeks;
oCollection of additional information about conditions of exposure (such as place(s)
and time of exposure to radioactive plumes) and details of the thyroid blocking
procedure (such as dosage and chemical form of stable iodine, exact time of
administration, multiple administrations);
The series of thyroid activity content measurements and additional information should be used for
the estimation of the time-integrated activity content in the thyroid gland and the associated
absorbed dose to the thyroid. If the high dose estimates are confirmed, consultations with qualified
health physicists and physicians are strongly recommended. Dose estimates in such cases can be
further refine with individual-specific parameter values for dose assessments (e.g. mass of the
thyroid gland and thyroid uptake function).
It is beyond the scope of this report to fix the threshold above which the dose evaluation should be
refined. TMT Handbook [Rojas-Palma et al 2009] considers that medical follow up and medical
assessment should be initiated for committed effective doses exceeding 200 mSv. The IAEA [IAEA,
2013] considers that an equivalent dose to the thyroid between 100 and 10 000 mSv is of health
concern and that above 10 000 mSv it is possibly dangerous to health.
64
III.9.5 External background and contamination of the skin and clothes
It is assumed that the contribution of the background to the subject thyroid measurement has been
characterised and subtracted. It is also assumed that contamination of the skin and clothes is
negligible. This may mean that the subject requires decontamination by, for example, washing the
skin and changing clothes.
III.10 Uncertainties in dose for adults and children assessed from
measurements of radio-iodine in the thyroid
For effective dose, only uncertainties relating to the exposure and the material should be considered
whereas for individual assessments of absorbed dose to thyroid uncertainties relating to the
individual can also be considered [ICRP, 2007]. The following describes sources of uncertainties and
gives an indication of the corresponding uncertainties in the dose-per-content functions.
III.10.1 Material- specific parameters and route of intake
For each age group the dose-per-content functions, for both effective dose and the 30-days absorbed
dose to the thyroid, are practically insensitive to:
the chemical form (particulate, gas or vapour)
physico-chemical properties of the inhaled material (particle size and absorption type)
route of intake (inhalation or ingestion).
There are significant differences, about 10% or 15%, only when the measurement is performed
within the first hours after intake.
III.10.2 Time of intake
Uncertainties on the time of intake give larger uncertainties on doses for measurements done within
one day after the intake, compared to measurements done at later times. For measurements done
from the second day after the intake, dose uncertainties are about 10-15% for an error of ±1 day in
time of intake, as it can be deduced from Tables III.3 and III.4.
III.10.3 Thyroid mass
The variability on thyroid mass affects directly the dose calculation: a smaller (larger) thyroid mass
means a higher (lower) absorbed dose (energy per unit mass) for a given measured activity in the
thyroid. The variation in mass within a given age group is about 50% for the foetus and newborn,
about 30% for children 1 to 10 year old and about 20% for adults.
III.10.4 Age group
Tables of dose-per-content functions calculated for adults to estimate doses to children would
grossly underestimate the dose to the children. Absorbed doses to the infant and to the 1-y child are
about 10 times larger than that to an adult for a given activity in thyroid, up to about 7 days and
become larger at later times. It is therefore recommended to use the dose-per-content functions for
the specific age group.
Assigning a subject to a given age group introduces a bias. When the age of the measured subject is
lower (higher) than that of the assigned age group, the dose is underestimated (overestimated). The
greatest difference in the dose-per-content function between adjacent age groups is between group
5 and 10 years old: for a seven year old using the dose coefficient for the 10 year old group gives a
bias of about 50%.
65
III.10.5 Dietary intake of stable iodine
The level of dietary intake of stable iodine affects the thyroid uptake fraction in case of an acute
inhalation of iodine but the dose-per content function is insensitive to it because the measurement
provides a direct estimate of the iodine content in thyroid (see details in Appendix B).
The level of dietary intake of stable iodine may also affect the thyroid mass and this affects directly
the estimate of absorbed dose to the thyroid.
III.10.6 Hypothyroidism and hyperthyroidism
Hypo- and hyperthyroidism alter the retention time of iodine in thyroid, but the absorbed dose to
the thyroid (and the dose-per-content function) is insensitive to it when the radioactive decay half-
time of the given isotope (8 days for I-131) is small compared to the iodine biological half-time (about
80 days).
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Potassium Iodide (Ki) Blockade of Thyroid Irradiation by 131I from Radioactive Fallout. Health Physics 78(6):
660–667.
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APPENDIX A. Factors affecting the measurement of radio-iodine in
the thyroid for adults and children
A detailed study about the influence of several parameters on the detection efficiency has been
performed using Monte Carlo simulation to calculate the detection efficiency for a set of age
dependent voxel phantoms and four different detectors [Gómez-Ros et al., 2017]. The main results
are outlined below.
A.1 Simulation details
A.1.1 Voxel phantoms
Seven human voxel phantoms corresponding to adult (male / female), child 15 years old (y/o) (male /
female) and children 1, 5 and 10 y/o have been used for realistic thyroid modelling. The voxel
phantoms have been obtained from HMGU phantoms Newborn, Child, Laura and Golem [Petoussi-
Henss et al., 2002] by scaling the voxel size, to fit the thyroid reference volume and body height
stated in ICRP recommendations [ICRP, 2002; Teles et al., 2016].
A.1.2 Detectors
Four spectrometric detectors have been considered for the simulations:
LE Ge (CIEMAT): The detector is a Canberra LE Ge (low energy Germanium) that contains a
germanium crystal 2.5 cm thick and 7 cm in diameter, with an active area of 38 mm2. An entrance
window made of carbon fibre and epoxy resin of thickness 0.05 cm is separated from the Ge
crystal by a 0.5 cm vacuum gap [López and Navarro, 2000; Gómez-Ros et al., 2008].
NaI (IST-ID, Portugal): The detection system is an ORTEC NomadTM Plus portable spectrometry
system equipped with an NaI(Tl) 2BY2 scintillation detector. It comprises a 2”x2” crystal (5.08 cm
diameter and 5.08 cm long) in a 0.05 cm aluminium crystal housing. The detector is also shielded
by a 0.5 cm aluminium layer, except in the entrance window. A shielding set was also used,
including 0.2 cm lead sleeve around the detector and 0.1 cm iron disk in the entrance window
[Bento et al., 2012].
NaI (NCBJ, Poland): The detector is a Canberra-Packard model 802-2x2 NaI(Tl) scintillator with a
2”×2” (5.08 cm x 5.08 cm) NaI(Tl) crystal surrounded by Al2O3and aluminum cover. The probe is
mounted inside a lead collimator with an aluminum cover. A second collimator is placed around
the probe to reduce the field of view [Szuchta and Ośko, 2016].
NaI (SURO, Czech Republic): The detection system is a prototype consisting of a single NaI(Tl)
crystal 2.54 cm long with the shape of a cylinder surmounted by a truncated cone (8 cm front face
diameter, 1 cm cylinder length, 5.08 rear faced diameter). The prototype is coupled to an
ORTECDIM-296 photomultiplier [Vrba and Fojtik, 2014].
The Monte Carlo models for these detectors are based on the technical specifications and they have
been previously validated, as described in the corresponding references given above.
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A.1.3 Monte Carlo simulations
The calculations have been performed using Monte Carlo code MCNPX [Pelowitz, 2011] to simulate
the coupled photon / electron transport. The efficiency at photon energy of 364 keV has been
calculated in all the cases with stochastic relative uncertainty lower than 1%. The neck to detector
distance has been measured along the straight line corresponding to the axis of the crystal detector,
passing through the centre of the thyroid, and from skin surface to the end cap window of detector.
A.2 Efficiency as a function of counting distance
Dependence with distance can always be fitted by an inverse square function:
ܧ݂݂(݀)=݇
(݀݀)
with a correlation coefficient greater than 0.99 (Figure A.1). This dependence is especially significant
at short distances (e.g., 5 mm variation around 10 cm distance can change the counting efficiency by
about 10%).
The difference in efficiency between adult and 5 years old phantoms decreases with distance but it is
still between 22% and 30% (depending on the considered detector) at 17.5 cm. Distances higher than
30 cm are required to obtain differences lower than 10% but in this the resulting efficiency might not
be sufficient to obtain the desired DL.
Figure A.1. Variation of the detection efficiency with the distance for different age voxel phantoms
and four detection systems (NOTE: Some measurement distances cannot be simulated because of
the geometry of the detector and the phantom).