You are calculating dose for radiation protection. It is correct to use it that way.

Its main use is to enable external and internal irradiation to be added as a means to demonstrate compliance with the Commission’s quantitative restrictions on dose, which are expressed in effective dose. In this sense effective dose is used for regulatory purposes worldwide.

Thanks, Joseph

My purpose is not radiation protection, but individual cancer risk estimate. As far as I understand, ICRP 103 effective dose is only meaningful for a standard human. Regulations are then based on the effective dose of this standard human.

What I have are individual patients (thin, fat, tall ..) and I would like to have an individual measure of cancer risk for each of them, based on MC organ doses. ICRP 103 may be a guideline, but it's not the primary purpose of this standard.

What do you use in my situation?

Once the dose is expressed as effective dose it is an estimate of detriment, mainly cancer risk. ICRP states that this is for doses lower than deterministic effects, about 0.05 Sv. Consequently, this is in the range of radiation protection. Nevertheless, the risk was calculated from even higher doses and extrapolated to lower doses.

The range of doses in your case should apply as the risk is considered linear. 

Do you plan to give the risk information to patients?

You might want to consider using Biological Effect of Ionising Radiation (BEIR) committee risk models that are organ dose specific.  

Thanks both for you valuable input. I will talk to my medical co-workers on how they handle patient information, that's a very good point. And I was not aware of the BEIR-commitee, this looks like a deep source of information.

As fa as I know ICRP reports (26/60/103)  have provided tissues/organs weghting factors based on the effects of ionizing radiation received by the Hiroshima and Nagazaki atmic bombs survivors derived from the rate of fatal cancers induced in such tissues/organs intended to be used for driving the effective dose when muliplied by the equivalent dose received by the tissues/organs from any radiologic examination. This gives a rough estimate of the level of severity of the risk involved from any radiologic examination.

However some countries perform regular national surveys from which National Diagnostic Reference Levels (NDRL) are extracted for every specific radiologic examination in terms of the effective dose. Then any radiologic center estimates the effective dose for similar exams (either on a goup of patients or individuals), compares it against the relevant NDRL and tries to keep it as much as possible lower than that level.

RadRAT can be used to estimate radiogenic cancer risks for different organs, depending on age at exposure, sex, and exposure rate.

https://irep.nci.nih.gov/radrat

http://dx.doi.org/10.1088/0952-4746/32/3/205

If you are matching voxel phantoms to patients (thin, fat, tall ..), you can calculate the  doses more accurately than compared to using a population 'standard' phantom. But in the next step, going from dose to risk, you are likely to be limited to a risk factor applicable for a population (e.g. RadRAT/BEIR), as individual-specific factors don't exist AFAIK.

I think Joseph is right – equivalent dose gives you rough estimation of cancer risk. Standard men is based on statistics and cancer risk assessment also. The models recommended by Alex are more specific, but again they refer to some averaging across population. May be if you aim at cancer risk estimation for individual patient you could consider evaluating individual sensitivity to radiation using some radio-biological methods.

You need to calculate the elevated relative risk (ERR) or elevated absolute risk (EAR) using the organ doses you have obtained and one of the various published risk models (BEIR VII, ICRP 103, UNSCEAR 2006). To calculate the lifetime risk, you need to calculate the ERR for each year, from the age at exposure up to about 100 years. For each of these figures, you multiply by the background rate for the organ in question at each age, and the 'survival function' (i.e. the probability of being alive at each attained age, conditional on reaching the age at exposure). The lifetime risk is basically the sum of all these figures (not including the first 5 years after exposure). The EAR version is the same except you don't multiply by background rates. Most experts suggest reducing risks by a factor of 1.5 or 2.0 if the total dose is below 200 mSv or was delivered using a slow dose rate. A more complete risk estimate can be obtained by calculating risks using both ERR and EAR methods and taking a weighted sum of both.

Sorry this is very long-winded. The easiest option, as mentioned above, is simply to use RadRat instead!

I agree with Joseph Alvarez in that the ICRP-103 is one good way to determine risk from a radiation protection purpose. When ICRP says: ".. nor should it be used for detailed specific retrospective investigations of individual exposure and risk", I believe their point is that the risk results are based on large populations and average responses; therefore it would not be useful to state that an individuals risk was increased by 0.03% or some such value.

Alex Malins' link to RadRAT and the documentation gave me a lot of hooks. With Bijan Hashemi's National Diagnostic Reference Levels I found figures to compare to. Thanks to everyone for contributing.

What is the active role of the external magnetic field affected on electrical corona discharge in hollow cathode tubes?

You need to use the organ dose and the BEIR VII cancer risk table to calculate the cancer risk for the US population. If you need to calculate the cancer risk for other population you need to revise the table yourself...

Given that "radiation risk" here means "radiation risks" for stochastic effects (cancer and heritable effects), effective dose can be used for risk estimates. However, it cannot be used for retrospective investigations of individual exposure and risk, because effective dose is calculated with a tissue weighting factor that is averaged over both sexes and all ages. Radiation increases risk for tissue reactions (formerly called deterministic or nonstochastic effects) with a threshold below which no effect would occur. Current ICRP's threshold is a dose that causes effects in 1% of exposed individuals occurring after a certain period of time (e.g., >20 years for cataracts of the ocular lens and >10 years for cardio- and cerebrovascular disease).

Article Classification of radiation effects for dose limitation purp...