Collective dose is defined in the ICRP Draft TG 79 report as the dose integrated over an interval for a set amount of time and for all individuals affected. Collective dose is intended for operational planning. The draft clearly proscribes use of collective dose for risk assessment and assigning detriment to a population. Collective dose requires the linear no-threshold risk model with no distinction for radiation type, internal or external, and dose rate.
The purpose of collective dose is for optiimization of radiation protection. Optimization is for total dose to a group, while radiation protection is for individuals. Is collective dose and optimization useful in your radiation program or is simply another regulatory hoop to jump through. Please give examples.
Dear Joseph,
I suggest you to see links in topic.
-Radiation Protection - ScienceDirect
https://www.sciencedirect.com/science/book/9781483283692
-Radiation protection - an overview | ScienceDirect Topics
https://www.sciencedirect.com/topics/medicine.../radiation-protecti...
-Optimization of radiation protection in the control of ... - IAEA Publications
https://www-pub.iaea.org/MTCD/Publications/.../Pub1118_scr.pdf
-Frequently Asked Questions on ALARA… …optimization of doses for ...
https://www-ns.iaea.org/tech-areas/communication.../faq-list-en.pdf
-Transcript of Potential Changes to NRC's Radiation Protection ...
https://www.nrc.gov/docs/ML1033/ML103330132.pdf
-radiation protection law: Topics by Science.gov
https://www.science.gov/topicpages/r/radiation+protection+law
Best regards
@ Alvaerz Sir. Very very relevant question. Collective dose (or even effective dose) appear to be highly simplified but actually they are based on confused (illogical) assumptions. ICRP it self is confused what to do or what not to do? In ICRP 60, they were recommending the use of effective or collective dose for risk estimation whereas in ICRP 103, they told not to do. The new report as you rightly mention " proscribes use of collective dose for risk assessment and assigning detriment to a population" actually the idea is not of any use.
Looking at age of worker (18-65) years, sex, individual sensitivity, smoking, ethics, region, food habits, wine drinking, pollution, adulterated food products, paints, chemicals, microwaves, mental tension and so on....
So you are right
it is simply another regulatory hoop to jump through.
and
Collective dose requires the linear no-threshold risk model with no distinction for radiation type, internal or external, and dose rate; which itself is wrong.
Better to use collective dose for crude regulatory comparison and optimization at least not for risk projections.
@Alvarez Sir, Collective dose (measured at 10 mm) depth and for varying radiations and additional internal exposures further complicate the issue. Monitoring at low doses itself is full of errors. Hence, Difficult to find organ doses. Only crude guesses can be made which are not of any physical significance hence no risk projections
ICRP recognizes that his collective doses deffinition has led people to misuse collective doses for summing up radiation exposures for a wide range of doses over infinite time periods and large geographical regions and to calculate on this basis radiation-related detriments. (http://www.icrp.org/docs/Physics_ICRP_Found_Doc_for_web_consult.pdf The collective dose, effective and/or equivalent, may be used:
- to assess the dosimetric impact of an activity or a source over a group of people,
- to assess the number of stochastic effects that could result from the exposure of a group of people. http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/37/115/37115700.pdf
@Florian
Misuse has extended to other disciplines, e.g., air pollution, and will continue without strong guidance. TG 79 made an good attempt at limiting the abuse, but inclusion for another purpose leaves the door open. The number of documents available on collective dose and their infusion in regulatory programs aid and abet continued abuse.
How has optimization and collective dose proved useful to a radiation protection program?
@Munish
As you noted, the many types of exposures and the ability to quantify (measure) them makes a sham of collective dose.
Do you have collective dose requirements at your institution?
Well, I agree with those who deem collective dose at least of secondary importance. The only situation where I think it makes sense to calculate the potential collective dose as a consequence of the operation of a nuclear or radiological facility in the future is the site selection process. Even if it is a rather uncertain and inaccurate measure of harmfulness of a source for this particular case it can help select the better solution giving advantage to a site with lower collective dose estimated in advance. No other applications would be desirable, I think, none of those connected to the dose limits and constraints of individuals.
No, we have no any requirement for collective dose in BG system of RP. The most weighting factors in optiimization of radiation protection are social (stakeholders?), economics, political and other considerations ...
As a good practice, in India, facility-specific target annual collective worker dose budgets are prescribed by the regulator. While submitting proposals to the regulator for major maintenance or repair tasks, the utilities need to indicate the collective worker dose budget for the activity and get this budget approved/ revised by the authority. Apart from fulfilling the regulatory dose limits (in line with ICRP limits) for the workers and the public, we do not have any prescription for collective worker or public dose based on the LNT hypothesis.
When you are looking at a number of sources of radiation and you want to give the most attention to the source that has the highest dose impact in the population, collective dose may be used to make a priority listing. For instance, there is a number of (legal) consumerproducts on the market that have some radioactivity incorporated. Policy might be to reduce the overall dose in the population due to consumerproducts. Collective dose might give you a good sense of the specific products you should focuss your attention on.
@Roelf
Consumer products does not seem to be important. These should be below concern as indicated by ICRP draft.
@Ratan
That does not sound like a good practice to have regulators assigning targets and approving budgets for maintenance and repairs. Indeed, it sounds like a good way to increase collective dose by being forced to accept an inadequate plan that requires more work to fix.
@Joseph
Consumer products were used as an example. I agree that most consumer products are below concern. However, there are some that make a difference, like for instance Th-232 containing welding rods (used in TIG-welding) that could be responsible for doses in the mSv range.
@Roelf
Welding rod doses are calculated on a worst case manner using improbable particle sizes. Nevertheless, how does one assign importance when the draft proscribes use of collective dose for risk assessment and assigning detriment to a population? Collective dose is for optimization in planning.
I have no intent to be argumentative. What is the use of collective dose? It has no meaning in terms of risk. Why should it have a meaning in planning?
@ Joseph
Collective dose might have less meaning in terms of absolute risk, but it has in terms of relative risk. You may choose from a list of exposures the ones that result in the highest exposure within a certain population and thereby give you a priority list to effectively reduce dose by specifically targeting those highest risk exposures.
If you calculate doses on a worst case manner only, then you might ask yourself what you are doing in the first place. Then collective dose has no sense either.
@Roelf
Relative risk has no meaning unless put in an absolute risk context. You stated,
"You may choose from a list of exposures the ones that result in the highest exposure within a certain population and thereby give you a priority list to effectively reduce dose by specifically targeting those highest risk exposures."
That is not collective dose.
I agree about worst case.
@Joseph
This relates to your comments regarding the role of regulators vis-a-vis operators in worker dose management. Your concern is not relevant in a healthy scenario, as in India, where both the regulator and the operator are highly knowledgeable well-trained professionals. The regulator does not ask for the impossible, and the operators take an assigned target as a challenge.
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