Question
Asked 28th Jul, 2015

Are there any other principle for radiation protection (ALARA ) as well as time, distance and shielding?

Are there any other principle for radiation protection (ALARA) as well as time, distance and shielding?

Most recent answer

29th Jan, 2022
Jozef - Sabol
Faculty of Security Management, PACR in Prague
Of course, one has also to consider the internal exposure due to the intake of radioactive substances where PPE play a significant role.
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Popular Answers (1)

29th Jul, 2015
Mushtaq Ahmad
Pakistan Atomic Energy Commission
ALARP, is an acronym for an important principle in exposure to radiation and other occupational health risks and stands for "As Low As Reasonably Practicable". The aim is to minimize the risk of radioactive exposure or other hazard while keeping in mind that some exposure may be acceptable in order to further the task at hand. The equivalent term ALARA, "As Low As Reasonably Achievable", is more commonly used outside the UK.
This compromise is well illustrated in radiology. The application of radiation can aid the patient by providing doctors and other health care professionals with a medical diagnosis, but the exposure should be reasonably low enough to keep the statistical probability of cancers or sarcomas (stochastic effects) below an acceptable level, and to eliminate deterministic effects (e.g. skin reddening or cataracts). An acceptable level of incidence of stochastic effects is considered to be equal for a worker to the risk in another work generally considered to be safe.
This policy is based on the principle that any amount of radiation exposure, no matter how small, can increase the chance of negative biological effects such as cancer. It is also based on the principle that the probability of the occurrence of negative effects of radiation exposure increases with cumulative lifetime dose. These ideas are combined to form the linear no-threshold model. At the same time, radiology and other practices that involve use of radiations bring benefits to population, so reducing radiation exposure can reduce the efficacy of a medical practice. The economic cost, for example of adding a barrier against radiation, must also be considered when applying the ALARP principle.
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All Answers (25)

28th Jul, 2015
Joseph L Alvarez
Alpha Beta Gamut
External dose calculation and calculation for protection assumes that time, distance, and shielding are primary. You further have to know the type and energy of the radiation, beam size and shape, and what parts of the body have the potential to be irradiated.
Internal dose includes the same principles, but with containment replacing shielding. Internal dose includes many other considerations. Some are chemical type and physical form, ability to contain, process control, and personnel protection.
1 Recommendation
29th Jul, 2015
Sajjad Ahmed Memon
Nuclear Institute of Medicine & Radiotherapy (NIMRA)
I agree with Mr Joseph. These primary parameters of TDS principle can reduce the dose of worker and public in general.
29th Jul, 2015
Mushtaq Ahmad
Pakistan Atomic Energy Commission
ALARP, is an acronym for an important principle in exposure to radiation and other occupational health risks and stands for "As Low As Reasonably Practicable". The aim is to minimize the risk of radioactive exposure or other hazard while keeping in mind that some exposure may be acceptable in order to further the task at hand. The equivalent term ALARA, "As Low As Reasonably Achievable", is more commonly used outside the UK.
This compromise is well illustrated in radiology. The application of radiation can aid the patient by providing doctors and other health care professionals with a medical diagnosis, but the exposure should be reasonably low enough to keep the statistical probability of cancers or sarcomas (stochastic effects) below an acceptable level, and to eliminate deterministic effects (e.g. skin reddening or cataracts). An acceptable level of incidence of stochastic effects is considered to be equal for a worker to the risk in another work generally considered to be safe.
This policy is based on the principle that any amount of radiation exposure, no matter how small, can increase the chance of negative biological effects such as cancer. It is also based on the principle that the probability of the occurrence of negative effects of radiation exposure increases with cumulative lifetime dose. These ideas are combined to form the linear no-threshold model. At the same time, radiology and other practices that involve use of radiations bring benefits to population, so reducing radiation exposure can reduce the efficacy of a medical practice. The economic cost, for example of adding a barrier against radiation, must also be considered when applying the ALARP principle.
5 Recommendations
29th Jul, 2015
Erik Strub
University of Cologne
To the "classic factors" time, distance and shielding you may add further principles in the sense of ALARA like:
- if you have the choice (like in experiments with radioactive tracers) reduce the amount of radioactivity to the necessary level
- practice what you want to do with a non-radioactive mock-up
- plan your works so that becomes clear where and when relevant doses could appear
- during some works assistance of further persons outside the radiation field might be of help
- for a complex work, if a considerable dose is expected, dose constraints e.g. on a daily basis might help to ensure that planned personal doses are not exceeded
...
1 Recommendation
30th Jul, 2015
Florian Glodeanu
Kinectrics
ALARA is the acronym of “As Low as Reasonably Achievable.” ALARA refers to the principle of keeping radiation doses and releases of radioactive materials to the environment as low as can be achieved, based on technologic and economic considerations.
Principles for Mitigating External Radiation Hazards
Time
Distance
Shielding
Principles for Mitigating Internal Radiation Hazards
Good Hygiene
Control of Contamination
Airborne Hazards
Personal Protective Equipment
30th Jul, 2015
Dion Janssen
MDT X-Ray
Even so, we see in personal protective equipment different materials being used for certain energies e.g. lead, 50-150 Kv,  leadfree 80-120 Kv  and hybrid materials 80-120Kv.  but maybe we go to much into detail then.  
30th Jul, 2015
Said Sabbagh
Fatih Sultan Mehmet Vakif Üniversitesi
The suitable source of radiation is also important: its energies, its reactions with the medium, and your method of calculation.
30th Jul, 2015
Sergio Faermann
Clalit Health Services
I would like to point out that the relatively recent requirements of ALARA for patients in radiodiagnostics, radiotherapy and nuclear medicine, introduced many more parameters to be controlled, and sometimes a contradiction to the philosophy of medical treatment.Therefore a balance between the MDs and the medical physicists requirements must be achieved.
30th Jul, 2015
Darryl Mcdougald
Duke University
It may go without saying but good laboratory practice can go a long way in reducing exposure.  Obviously the particular isoptope or the energy of the material being used can be a big variable how effective the ALARA practices can be.
31st Jul, 2015
Laith Najam
University of Mosul
as i know the tree parameters time , distance and shielding are very important in reduces   external dose 
and the distance is the most important because of inverse square law 
and it is also very useful  to know the energy of incident radiation 
and i has finished an M.Sc. thesis under title
Determine The Ability of Some building Materials on The Attenuation of Gamma Rays For use as Shields
1st Aug, 2015
Jim F Malone
Trinity College Dublin
Time, distance and shielding are really important in radiation protection.  However, to some extent the importance attributed to them relies on an assumption.  That is, you know accurately where the radiation beam or source is.  This is not always a safe assumption.  For example the position of x-ray beams is, in theory, usually indicated by a light beam that is supposed to coincide with it.  But, the light beam and the x-ray beam can and do get out of alignment.  When this happens, not knowing exactly where the boundary of the beam is, possibly becomes more important than the three basics.  There are lots of other ways that we can be misled about where the radiation source or the beam is.  So I rate this issue highly, even though it is not often mentioned.
1 Recommendation
2nd Aug, 2015
Sergio Faermann
Clalit Health Services
Agree with you Jim, but as I pointed out in my answer, this issue is linked to an efficient Quality Assurance program of the specific machine or radiation source you are dealing with ( i.e..a balance between the different populations you are monitoring: the patient, the radiation worker or the general population).
2nd Aug, 2015
Jim F Malone
Trinity College Dublin
Completely agree Sergio,
Jim
3rd Aug, 2015
Hanno Krieger
@Jim,
you are right, the alignment of x-ray field and light field must be guaranteed. But this is the task of quality control for therapy machines or x-ray equipment in radiology. In technical applications of sources a slight dealignment would be no problem because you expose materials and no humans.
A very important point is the avoidence of incorporation of radioactive substances where ever they are handled. That means gloves, avoiding ingestion or inhalation and of course the careful dealing of wastes. 
1 Recommendation
3rd Aug, 2015
Joseph L Alvarez
Alpha Beta Gamut
ALAP, as low as practical, was the original concept proposed by ICRP and several national organizations. The ICRP publication was held up to change to ALAP to ALARA, as low as reasonably achievable. The change was imposed by a few committed to the LNT. Practical was the problem. The LNT supporters felt the term practical allowed too much leeway. The insertion of the word 'reasonably' was a compromise that prevented the term ALAA. Regulatory agencies effectively enforce ALAA when they demand annual reductions in individual and collective dose. ALARP is not recognized by all agencies. Many agencies that proclaim ALARP as guidance still practice ALAA.
The LNT is a regulatory assumption and does not conform to reality. 
2 Recommendations
6th Aug, 2015
Nabil Morcos
Macquarie University
Yes to all the contributors!!
Time, Distance, and Shielding. But, do not forget the most important: The quantity and intensity of the radiation source!!!
6th Aug, 2015
Sergio Faermann
Clalit Health Services
Nabil
It does not matter what source, activity or exposure rate. The same principles hold for every situation.
1 Recommendation
6th Aug, 2015
Erik Strub
University of Cologne
@Sergio
As I already wrote above, sometimes there is a choice which source(s) are used. Then, of course, it is in accordance with ALARA to choose the lowest activity which fits the purpose.
E.g. if you use radioactive tracers for chemical separations and you can get significant results with kBq activities, ALARA tells you not to use MBq.
1 Recommendation
6th Aug, 2015
Sergio Faermann
Clalit Health Services
Erik
I agree with you , and in this case you could use also the optimization principle.
11th Aug, 2015
John Hageman
Southwest Research Institute
In addition to Time, Distance and Shielding the use of good training and the proper use of survey instruments and techniques apply to ALARA. When it comes to ALARA for contamination, proper engineering controls, protective clothing and decontamination apply to ALARA. Use of remote technology is also an effective ALARA practice. Practicing a procedure with non-radioactive sources is a very good Time reduction technique.
1 Recommendation
21st Aug, 2015
P. Ashokkumar
Government of India
All rules and laws (ALARA, Time Distance Shielding, Training etc.) are OK.. But for radiation protection, on the the spot  use of common-sense supersedes everything.
27th Apr, 2017
Nobuyuki Hamada
Central Research Institute of Electric Power Industry
The International Commission on Radiological Protection (ICRP) uses three fundamental principles of radiological protection: namely, justification, optimization, and the application of dose limits.
The principle of justification can be defined as "any decision that alters the radiation exposure situation should do more good than harm".
The principle of optimization can be defined as "the likelihood of incurring exposure, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking into account economic and societal factors".
The principle of the application of dose limits can be defined as "the total dose to any individual from regulated sources in planned exposure situations other than medical exposure of patients should not exceed the appropriate limits specified by ICRP"
The principles of justification and optimization apply in all exposure situations, but the principle of the application of dose limits only applies in planned exposure situations.

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Further on, he shows that if the mass of a body at rest (i.e. stationary in the reference system) is equal to m0, when it is brought to speed v it has a mass amplified by a factor γ = 1 / √ (1-v ^ 2 / c ^ 2).
That is, it shows how the kinetic energy transferred to the body has transformed into gravitational mass making the mass equal to m = γ m0.
Einstein himself says it personally in the video:
On the other hand, experiments are known in which energy is transformed directly into mass.
For example, just think that a gamma ray with energy greater than 1.02 Mev, interacting with an atomic nucleus gives rise to an electron-positron pair with each a rest mass of 0.51 Mev.
The energy of the gamma photon was then transformed into mass at rest exactly as predicted by Relativity.
Now let's imagine a metal box, with perfectly reflecting internal walls, containing 10 ^ 21 gamma photons, each of which has an energy of 0.51 Mev.
We ask ourselves: does this box have the same mass as an empty box?
The energy of 0.51 Mev corresponds to the rest mass of the electron m = 9.1 10 ^ -31 kg.
So the mass of such a box, according to Relativity, should be M = 9.1 10 ^ -10 kg, which is a relatively high mass (it is of the same order as the mass of a grain of dust).
If this box is accelerated its mass INCREASES. For example, if it is brought to a speed v = 0.99999 c we have γ = 1 / √ (1-v ^ 2 / c ^ 2) = 316. That is, the box would weigh 316 times more.
The question is: suppose a hole is made in the box so that the radiation is allowed to escape from the box. Would the outgoing radiation have the same FREQUENCY as the photons that had been introduced into the box?
The answer can only be one: NO.
The frequency of each photon must have increased 316 times over the frequency of the photons that had been introduced into the box.
Of course, the frequency of the radiation coming out of the box would be subject to a relativistic Doppler effect, that is, moving away from the observer its frequency would decrease. Approaching it would increase. Therefore in the point of minimum distance from the observer it would be precisely f ’= γ f0 (Transverse Doppler effect).
The reason why I would like to open a discussion on the mass of radiation is that although Einstein and Feynman express themselves clearly on the subject, there are obscure physicists (for example a certain Okun
who affirm that the energy of a photon moving in a gravitational field remains constant.
Others even affirm that the MASS of a body subject to an increase in kinetic energy remains constant, calling MASS INVARIANT the parameter m0 that appears in the relativistic formula
E ^ 2 = (m0 c ^ 2) ^ 2 + (pc) ^ 2
making us think that the mass of a body is the same in every frame of reference.
In other words, according to them, the mass of a body at rest and that of a body with velocity v = 0.99999 c are equal.
What do you think?

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