Questions related to Radiation Dosimetry
In any OSL phosphor we require optical energy more that the thermal trap depth of that trap for optical stimulation. For example in case of Al2O3:C we require 2.6 eV photon to detrap the electron from the trap having 1.12 eV thermal trap depth. How are they related to each other?
What is the logic or significance for using the inverse square factor for calibration of in vivo dosimeters (placed on surface) to the dose measured by ion chamber at dmax?
All organs are not equally damaged by same amount of radiation dosage. But, on which basis equivalency is measured? (i..e 1 gray in this organ equals 10 sievert) Is it arbitrarily qualitative or quantitative as well? Then what is the quantity? ( concentration of reactive oxygen species, DNA mutation frequency, Radiative cellular apoptosis..., percent Coagulation of biomolecules). But all humans are not equally affected by same amount of radiation energy applied on same organ. Then, does the equivalency chart vary from person-to-person, species-to-species, or year to year ?(i.e. refining of values with increasing precision) I f so, thaen how the equivalency are standardized?
I know how to calculate the MU time but not sure how to get the cumulative dose. I have gone through the Radiation Physics book by Faiz. However no clear cut approach is shown for getting the cumulative dose? So my question is 1) Is there any approach by which cumulative dose can be calculated? or it is prescribed by the radiologist? 2) Do we need to optimize the dose distribution for telecobalt therapy?
Hi, everyone! I am studying the damage processes in crystalline ceramic samples under energetic ion irradiations. My samples were irradiated at room temperature. Now I want to consider the annealing effect induced by the temperature increase of samples during irradiation(Is this necessary?). And the temperature change in samples during irradiation should be determined. To my knowledge, I should firstly determine how much energy of ions can be converted to the internal energy of target system, and then calculate the temperature change according to the equipartition theory (E=3*N*k*T) or Q=c*m*delta-T (c is the specific heat). Is that right? The question here is that how to determine the energy fraction of ions would be converted to the internal energy of system? Can anyone help to answer this question or give some other suggestions ? Many thanks to everyone!
I work at the center that has a TLD-Reader model 4500. I know the that main sources of uncertainty in environmental dosimetry are: energy and angular dependence, temperature, humidity, linearity, ECC,RCF,Zero dose, ....
may you tell me the procedure of uncertainty calculation for these factors?
I need some training on the use of Matlab, Monte Carlo, C++ for image processing, image reconstruction, analysis, radiation dosimetry and treatment planning.
1. Can Compton Scattering like scattering happens for K shell electron like it happens for valence shell electron for X and Gamma Ray?
2. If yes, probability is more for K or Valence Shell electron? And more importantly why its high (either K or valence shell)?
We want to buy an underwater detector for radiation protection purpose. Differentiating between natural (like radon and thoron) and artificial (like iodine and cesium) radio-nuclides is of more important in this project. We just want to buy one detector to do some test and get familiar with. After verification we plan to deploy a network in the sea. So currently I need no accessory or central server, I just need a stand alone device which I can communicate with a laptop.
I checked out AT6104DM(atomex), sara water(envinet) and Katerina. I contacted with the companies. Now for financial purpose I need to know price of them.
If any body has bought one of these devices or similar, kindly give me a clue about the price of them.
Also a training course by experts of company would be useful, Can you guess how does it cost?
I need to know if it is possible to measure any amino acid by any method after radiation exposure from serum of human blood. If yes, can I get the protocol? Are there any specific amino acids in particular that responds differentially to radiation exposure?
In the case of drugs, HED calculation has been well known. However, I think the absorbed dose of radiation is not applied for that, because it is just a wave of radiation and penetrates the whole body.
For example, I'd like to investigate the effect of low dose radiation below 100mSv (10cGy) on mice. Should I expect the same results of mice to human?
The UK HPA recommends the use of the Pka to measure reference levels in CBCT examinations. We are measuring this in Brazil, but we have few results to compare.
I need some real data of a patient treated with chemotherapy. This data includes the tumor reduction with time. For example, what is the tumor size (or the number of cancerous cells) just before the first dose, the second dose, the third dose,..,etc.? Any type of cancer is acceptable.
Any answer is appreciated.
Use of dicentric counting Chromosomal aberration test for biodosimety for ionizing radiation is very common technique. How much reliable method is this ? i m worried about this because of limited number of dicentrics formations in the exposed person.
As we know, a high energy proton will continuously lost its energy along the travelling path in medium. For example, in proton therapy for cancer treatment, a proton beam irradiates a patient and releases all of its energy at the end of path in certain specific depth, so called Bragg peak. How do those existing protons which have no energy and stop at specific depth interact with surrounding molecules in tissue? Will it combine with a electron and become a hydrogen?
The source consists of eight encapsulated Cobalt-60 pencils arranged in a cylinder. Each source pencil is of 1.4 cm outer diameter and 45.2 cm length. I want to compare the observed dose with theoretical calculated data using "Line source" formula not "point source". Is there any software available of dose calculation for "Line source"?
Please see the attached file for more information.
Reading this paper about the metabolic fate of chondroitin sulfate, where 24% of "Administered radioactivity" ends up in feces after 24h of administration
Single dose in rats of 16 mg/kg and 90 Fci/kg, activity of 12.5 mci/mg,
3H-chondroitin sulfate (3H-CS) was prepared by reduction with sodium 3H-borohydride.
I've never taken any radioactivity/physics courses in my degree, so Im lost on how to determine the actual concentration that they found in the feces in a molarity or w/v form. Could anyone help me understand the calculations I have to do?
Paper in question: http://www.vitaflex.com/res_af401a.php
From kV and mAs values and without the use of any detectors, how can you find the dose delivered to patients? When using an X-ray, for diagnosis purposes, if you know only the two values of mAs and kV, can you determine the dose or maybe even estimate the dose delivered to the patient? Without the use of any modern detectors.
I have portable 30mA X ray machine with the following specifications:
Output 30mA at 52 KV
20mA at 68 KV
15mA at 85 KV
Timer 0.06mA to 6.0
Tube 1.5 mm sq. Focal Spot X-Ray tube
Input 230V, 15 Amps
L. V. Compensation 210 to 250V
Beam Limination Cone with Centering Device
Weight 15 Kgs.
Dimension (mm) 250x175x250
Can somebody guide me to calculate the dose in gray (Gy)?
Thanking you in anticipation.
In calculation of the absorbed dose in radionuclide scintigraphy, the absorbed dose in tissue T from radionuclide in a single source organ S is given by:
D(T <-- S)= As x S (T <-- S)
where As is the cumulated activity.
I want to calculate the absorbed dose of the kidney in renal scintigraphy using 99mTc-DMSA. I have measured the activity of the rat's kidney using dose calibrator. for calculation of the absorbed dose in a period of time, I need the S-value for rat's kidney and 99mTc-DMSA.
How can I find or calculate it?
Is there another way to calculate the absorbed dose in rat's kidney from measured activity?
What is the best method to assess the absorbed dose by the target organs during an X-ray computed tomography?
I have made an excel program for differentiating the global radiation values into direct and diffuse radiation for vacuum tube solar collectors. In order to validate my calculations and equations, I need values of global radiation and corresponding values of direct radiation, both measured at the same time, location and conditions.
If anyone is willing to share those, it will be of great help. Also, please suggest how do I cite the data while using it in my project.
I performed the radiation dose calculations and radiological consequences of a hypothetical accident by HotSpot, How to calculate values of error bars shown in figures? How to calculate combined relative error?
I want to do dosimetry with dosxyznrc code and for this purpose I need to make egsphantom with ctcreate code from thorax phantom dicom images. My phantom is from thorax region and includes three material; the lungs, the heart and the spinal cord.
thanks in advance to your attention or maybe your answer.
We have measured the radiation doses at different positions of a Cobalt-60 gamma irradiator room using Fricke and Ceric-cerous dosimeters. Now, we want to compare and validate the obtained dose with established formula (to calculate radiation dose) and dose calculated by Monte Carlo simulation. I need help to calculate the dose using Monte Carlo simulation. It will be a great pleasure for me, if there is anyone who has expertise in Monte Carlo simulation and interested to help me.
Thank you very much.
I tried searching it in google indeed, but just found some old and new articles on modeling of radiation environment that were of no use to my problem. What I'm exactly looking for is a set of information like what we have for gravitational field (Spherical harmonic coefficients) that describes the magnetic field strength and charge densities in proportion to solar activity.
Let's put it this way: I want a model to use it to calculate the amount of radiation dosage absorbed by spacecraft in a trajectory around Jupiter (or Earth) for a certain amount of time.
The typical properties of them is the 0.5 mT of splittings from the central line at both sides, but what are the other evidence; MW power saturation features, decay, kinetic features,... etc.
Thanks in advance
Many radiotherapy modalities use small fields or beam overlapping during treatment. Dose measurement under such circumstances can be accomplished by systems planning or direct measures (ion chambers, radiochromic films, etc,.)
The characteristics graph of Geiger Muller Counter always keeps going up and does not drop down . It may remain constant over an interval but does not drop down on the graph scale. Why it does not come down after going up?
One idea to improve a TLD response sensitivity and other its characteristics is to add co-dopants to the phosphors. Is there any rule for co-dopant selection in a specific phosphor which already has a dopant? Is there any way to predict the effects of adding a co-dopant to a TLD phosphor?
According to the definition, CTDIvol is obtained by dividing CTDIw by pitch factor.
The use of tube current modulation results in different CTDIw values for every rotation. Even though CTDIw is not constant during the whole scanning, the CT scanner displays a CTDIvol value at the end of the examination. How is this value calculated? I'm especially interested in how Siemens Somatom machines calculate it (in case different CT producers have different methods).
Does anyone know that : How to measure the decay time of scintillator material? I would like to measure the decay time and afterglow of scintillators which are used for X-ray detection (particularly with synchrotron source).
I was just wondering if anybody has any experience with using Ar + Cl mixtures as a fill gas in GM counters? What pleateau slope, length and starting voltage can one expect as a function of increasing Cl concentration in such mixtures at say about 100 mbar? As far as I know, even low concentrations of Cl, say between 0.1% - 1% are sufficient to obtain the required quenching. I would appreciate any feedback on this. Thanks in advance !
Hi every body
In our radiotherapy center, there is a Varian Linac 2100C/D with energy 6MV. However the Flattening Filter Free (FFF) mode is not available. I need PDD, profiles at several depth measured for fields 2x2, 4x4, 6x6, 8x8, 10x10, 20x20, 30x30 and 40x40 and also Sc and Scp for Varian 2100C/D 6MV energy without Flattening Filter (FFF) for comparing to simulation data obtained by Beannrc code.
OR, does the use of these radionuclide tracers, themselves, add a significant risk of causing cancer in patients?
The dose of ionizing-radiation from the tracer used in one PET scan, for example, typically exposes the patient to about 25% of the maximum allowable annual radiation exposure permitted for nuclear workers (which is a VERY high limit = to over 200 standard/modern medical chest xrays, meaning a patient is getting exposed to the equivalent of about 50x chest xrays ALL AT ONCE for each PET test).
if there is a patient planned to treated with 25 fractions with 200 cGy, for 5 days per week (5 weeks), let he absent for 3 days for the first week and absent 2 days for the second and finally absent for 10 days in the last one, how to calculate the actually received dose and the remaining
I think direct measurement with anthropomorphic phantom is the best way, but this method needs expensive phantoms and is time consuming according to calibrate and read TLDs. Is an alternative method to asses organ doses with less difficulties?
In radiation dosimetry for acceptance test of computed tomography; papers speaking about ' CTDI ' more than 'MSAD' ;
seem that MSAD is theoretical concept but maybe accurate than other index to estimation of dose in QC.
How be measured this index in practice?
Thanks in advance
in radiotherapy procedures fractions of dose delivering to the tumor from different planes, i would like to know is it possible to measure the accurate absorbed dose using TLD material. If possible what are the exact location of placing the TLD material on the patients body, in case of different therapy procedures.
I have undergone chest x-rays for 8 times in only 9 months. I am told each time u go to an x-ray your life span is short by 3 years. So, I imagine I have lost 27 years of life ahead and predisposed to cancer attack risk. But again I am told that if I take antioxidants like resveratrol those free radicals as a result of x-ray exposure can be removed. When I ask doctors they don't give me a clear answer; I am now asking the experts who know what's on ground . What can be an advise to me looking at the above concern?
Im looking to study bile acid transport via apical sodium codependent bile acid transporter (ASBT) in CaCo-2 cells. I have read several papers with brief descriptions of radiolabled bile acids in a transwell assay.
A) I was wondering if any on has done this via fluorescence instead of radioactivity?
B) I have never done radioactivity. Different paper use different labeled bile acids (i.e. 14C, 3H, ect.)....is there a specific reason?
C) Does anyone have a detail protocol for this assay?
I am looking for how to apply the dose constraints for OARs in the case of a RC3D hypofraction treatment.
Example; RC3D case of lung cancer treatment is a vector of 66 Gy, for the DVHS v20 is applied to the healthy lung <30% and the V30, <20%
My question is when the doctor decided to do a treatment with a dose of 30 Gy in 10 seance. Is what you apply according to the same dose constraints given that doses, per seance, are not the same?
I am working on electromagnetic field effects on pregnant rats, so I want to now how can I measure SAR for rat's bodies.
Thanks for your help.
We would like to investigate the effects of diagnostic x ray irradiation on lipid peroxidation in different animals tissues. Therefore we would like to know if somebody had already determined a dose of radiation (Gy) exerting meseurable changes in lipid peroxidation.
The International Commission on Radiation Protection (ICRP) proposed a set of operational quantities defined to allow for calibration of ionizing radiation protection instruments for measurements to show compliance with the system of protection quantities. These measurable quantities are the ambient dose equivalent, the directional dose equivalent, and the personal dose equivalent.
An earlier question "What is the difference between Sievert and Gray? A practical question concerning the SI units for ionizing radiation?" addressed the confusion of Sievert and Gray and its use in radiation protection programs. This question is a continuation and addresses the practical aspects of calibrating and interpreting instruments used for radiation protection.
The ICRP asserts it has proposed measurable quantities, but have defined them by calculation. The calculation is ideal and impractical for measurement as a parallel expanded beam of a single energy is not possible to produce. The point of dose is at a depth in a sphere or slab, a location not accessible to an instrument. Actual calibration must be performed free-in-air with a non-uniform beam and with physical constraints that may not be negligible. Calibration is to an instrument that is energy dependent and does not have the backscatter characteristics of a sphere, slab, or human body.
use ImageJ software to get the ADC value, but, when I get the ADC map, the resolution is low, i can not draw the ROI around tumor, and before the software told the image is not 32 bit..I used 1T Bruker ICON Siemens, b value is 0, 800! And also, I wonder ImageJ can get ADC value from only two b values or multiple b values? Do anyone know about software can use multiple b value for ADC value? (DTIstudio?). Please refer the attached file and help me sold the problem! Thanks!
Geiger counters work in environments with different kinds of radiation types. How dose it measures radiation dose in sivert unit?
if you know an article addressing this question with quantitative results will be great
treatment site , GYN, skin ,etc
thank you in advance
I want estimate effective dose from cardiac CT with PMMA phantom and ionization chamber and a dose calculator software. is any other way to estimate E dose?
I have created a DICOM file in MATLAB and hope to import into Pinnacle TPS. I have double check this DICOM file can be opened in ImangJ or DICOM viewer, but when this file is imported into TPS, this file can be recognised as DICOM but warning message is shown: the data dose not exsit./ the path and/or file predix is invalid.
dose anybody meet the similar thing before? I paste the head file below. please could you help me to check? thanks.
FileModDate: '08-Feb-2015 15:30:42'
FileMetaInformationVersion: [2x1 uint8]
ImplementationVersionName: 'MATLAB IPT 7.1'
SpecificCharacterSet: 'ISO_IR 100'
InstitutionName: 'RAH ONCOLOGY'
ReferringPhysicianName: [1x1 struct]
OperatorName: [1x1 struct]
ManufacturerModelName: 'Brilliance Big Bore'
PatientName: [1x1 struct]
ProtocolName: 'QA Laser Physics/PHYSICS'
ImagePositionPatient: [3x1 double]
ImageOrientationPatient: [6x1 double]
PixelSpacing: [2x1 double]
WindowCenter: [2x1 double]
WindowWidth: [2x1 double]
Is there any reference data available for reliability and availability of GM based radiation survey meters which are used for routine survey purpose in industrial or medical institutions.
If you are a clinical medical physicist, what are the major challenges in your department in order to perform invivo dosimetry for each individual patient when he/she is receiving radiotherapy or undergoing for a diagnostic radiological procedure?
I am working with dose issues in CT. In my former institute we used TLD measurements inside the Rando phantom for accurate dose estimations. Besides the fact that these measurements are very time consuming, the phantom + equipment cost a lot of money. Do you have suggestion about any alternatives? May be simulations?
I have a Geiger counter that not only displays counts but also the dose rate in Gray/h. The dose rate is calibrated to gamma radiation from a Cs-131 source.
If I'd have a U-238 source instead, can I estimate the dose rate from the rate the Geiger counter is displaying?
If I'm correct U-238 gammas have about 50 and 110 keV, while Cs-131 is 662 keV. Does that mean that as a rule of thumb I could divide the displayed rate by 6 to get an estimate of the actual dose rate?
I think it should be possible, if the detection rate is the same for both gammas and pure U-238 is present. Is that correct?
In a first look, both are fluorescence, giving immediate light emission on irradiation. Mechanism wise both are similar. If both are same then why different terminology? Or is there any technical difference?
Is there any literature evidence on symmetric planning and its advantages over asymmetric planning in ldr brachy. Thanks
I want to built a miniphantom for SC measuring using EBT2 film for small field 6MV photon beam, 2 plexiglass cubes (density 1.19g/cm3) dimensions 3x3 with height of 5 cm for top and 10cm for bottom as a holder.
1- Which materials do you recomment for top for electron contamination in small field film dosimetry? Brass top or plexiglass
2- Is it necessary to calculate the equivalent thickness for top (plexi or brass)?
3- What dimensional did you consider for your phantom? lateral dimensions and top thickness?
Treatment time (for teleterapy unit) is similar with monitor unit (for LINAC).
Manual calculation for MU or time depends on dose delivery technique, there are SSD tech. and isocentric tech.
To calculate MU in LINAC,
If we calculate in SSD tech., we used data of PDD.
if we calculate in isocentric tech, we used data of TMR.
How does to calculate treatment time Cobalt-60 teletherapy unit for in SAD/isocentric techique?
we use TAR or TMR ?
if we have data of TAR and PSF Cobalt-60 from BJR Supplement 25, to calculate time in isocentric tech, we use TAR data? or must convert TAR to TMR ?
Thanks a lot for your discussion.
AAPM Report Task Group 71 described recommendation for manual calculation of Monitor Unit calculation for photon and electron beams. In this report, d0 =10 cm (depth of normalization) used as reference depth. It not use dmax (depth of maximum dose) as reference depth.
How does if we do manual calculation of treatment time cobalt?
Is AAPM Report TG 71 applicable for calculation of treatment time cobalt-60 ?
can we use this recommendation?
if yes, how many reference depth that we must choose?
thanks a lot for your discussion.