Re: Effective Dose Equivalent

[rkathren@tricity.wsu.edu (ron kathren)]

Al --

What you are missing is the fact that you have exceeded the deterministic
effects level.

Ron

> The concept of total effective dose equivalent or TEDE requires addition of
>external dose to internal dose.  The internal dose is calculated by
>multiplying the organ committed dose equivalent by an appropriate weighting
>factor.  The weighting factor is chosen so that the risk of fatal cancer or
>hereditary effects or non fatal cancer hypothetically caused by the
>committed organ dose equivalent would be the same as the hypothetical risk
>from exposure of the whole body to a dose equal to that of the organ
>multiplied by the weighting factor.  However, I have a conceptual problem
>with that idea, particularly for large doses.
>
>For example:  Suppose the testicles receive a dose of 40 Sv and the rest of
>the body receives zero dose (remember this is hypothetical).  The equivalent
>dose is 10 Sv (weighting factor of 0.25 in 10 CFR 835).  10 Sv will almost
>certainly result in death.  40 Sv to the testicles will result in sterility,
>but probably nothing else (at least I can't find any risk numbers for fatal
>testicular cancer as a function of dose).  So, how are the 10 Sv and the 40
>Sv equivalent in risk?
>
>A similar problem appears if the testicles are exposed to 4 Sv (equivalent
>dose of 1 Sv).  4 Sv could cause sterility.  1 Sv could have a significant
>risk of cancer.  Are those two risks equivalent?  Even worse: the DOE
>Radiological Control Manual requires establishing special control levels for
>individuals whose total lifetime dose in rem exceeds their age in years
>(based on an NCRP recommendation).  Would it make sense to establish such a
>level for such a person?
>
>What am I missing here?
>
>Is there an upper limit of dose above which the concept of equivalent dose
>does not apply?  Maybe 50 mSv per year?
>
>
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