effective dose equivalent

[wlrun3@aol.com]

   ...if we reposition the ed/tld to the head and the worker receives 100 mR per ed and the ed and the tld agree with each other, what happens to that number before it reaches the form four...

   ...i know that effective dose (deep dose equivalent) equals dose equivalent times tissue weighting factor and that the nrc uses seven organs, one of which is a "remainer" (all other organs not listed)...

[wlrun3@aol.com]

I'm not quite sure what you're asking.  The head isn't a separate organ, so a dose received to the head is a whole body dose.  One hundred mR to the head should show up as 100 mR TEDE and just to make the paperwork easier, you'll probably get assigned 100 mR to all the extremities.  You won't get assigned any specific CDE organ doses.

   1...absorbed dose equals energy per mass...

   2...dose equivalent equals absorbed dose times quality factor...

   3...effective dose equivalent equals dose equivalent times tissue waiting factor......external(synonymous with deep dose equivalent?)...

   4...committed dose equivalent equals intake divided by non-stochastic annual limit on intake...

   5...total organ dose equivalent equals committed dose equivalent plus effective dose equivalent...

   6...committed effective dose equivalent equals intake divided by stochastic annual limit on intake...

   7...total effective dose equivalent equals committed effective dose equivalent plus effective dose equivalent...

   8...shallow dose equivalent is measured at .07 mm...

   9...lens dose equivalent is measured at 3 mm...

   10...extremities are knees and elbows and below...


   ...i am not sure how/when the tissue weighting factors are applied to determine effective dose equivalent...

[wlrun3@aol.com]

Great.  You know the definitions of TEDE, DDE, SDE-ME, and whatever.  What was your question?

   ...Sorry... the question is how are the tissue weighting factors used in determining effective dose equivalent...

   ...are you a dosimetrist/health physicist...

[spentfuel]

from 10CFR20 definitions

Weighting factor WT, for an organ or tissue (T) is the proportion of the risk of stochastic effects resulting from irradiation of that organ or tissue to the total risk of stochastic effects when the whole body is irradiated uniformly. For calculating the effective dose equivalent, the values of WT are:

Organ Dose Weighting Factors

Organ or Tissue WT
Gonads 0.25
Breast 0.15
Red bone marrow 0.12
Lung 0.12
Thyroid 0.03
Bone surfaces 0.03
Remainder 10.30
Whole Body 21.00

1 0.30 results from 0.06 for each of 5 "remainder" organs (excluding the skin and the lens of the eye) that receive the highest doses.

2 For the purpose of weighting the external whole body dose (for adding it to the internal dose), a single weighting factor, wT=1.0, has been specified. The use of other weighting factors for external exposure will be approved on a case-by-case basis until such time as specific guidance is issued.

I actually attended training on the new part 20 prior to implementation of the new reg and that basically consisted of a consultant that worked for the NRC saying "what we really meant was" when trying to explain what each new term was.  All written in legal ease for all us to enjoy.

I think your both on the same page just reading things a bit different.

If you look at footnote 2 it trys to say dose weigting factors for external whole body dose is 1.

Weighting factors apply to internal dose usually from an uptake unless your looking at medical doses.  In the example you gave above weighting factors would not apply.

hope that helps

sf

[Motown homey]

   ...if we reposition the ed/tld to the head and the worker receives 100 mR per ed and the ed and the tld agree with each other, what happens to that number before it reaches the form four...

   ...i know that effective dose (deep dose equivalent) equals dose equivalent times tissue weighting factor and that the nrc uses seven organs, one of which is a "remainer" (all other organs not listed)...

I don't think that the new approved method of calculating EDE has anything to do with weighting factors.  Check out http://www.nrc.gov/reading-rm/doc-collections/gen-comm/reg-issues/2004/ri200401.pdf.  I think that it will tell you how to go about substituting Effective Dose Equivalence for Deep Dose Equivalence if your company decides that its the proper thing to do.  In a previous job, I was part of a NEI subcommittee that petitioned the NRC to allow this. 

[wlrun3@aol.com]

I don't think that the new approved method of calculating EDE has anything to do with weighting factors.  Check out http://www.nrc.gov/reading-rm/doc-collections/gen-comm/reg-issues/2004/ri200401.pdf.  I think that it will tell you how to go about substituting Effective Dose Equivalence for Deep Dose Equivalence if your company decides that its the proper thing to do.  In a previous job, I was part of a NEI subcommittee that petitioned the NRC to allow this. 

   ...exactly what i was looking for...

   ..." Part 20 goes on to specify that this DDE be
measured at the part of the whole body with the highest exposure. This DDE can be directly
measured with available dosimeters and, in most exposure situations, provides a reasonable,
conservative, and often the best estimate for EDE from external sources (EDEex)."

   ...this explains the commercial nuclear power practice...

   ...what would be an example of a job where neither the DDE approach or the two dosimeter method is used and the tissue weighting factors are brought into play to calculate EDE...

   ...can't tell you what a pleasure it is to get this kind of answer to a sincere question on this forum...

   ...i am consistently impressed by the value of the nukeworker.com forum as a reference resource...

   ...thankyou...

[wlrun3@aol.com]

from 10CFR20 definitions

I actually attended training on the new part 20 prior to implementation of the new reg and that basically consisted of a consultant that worked for the NRC saying "what we really meant was" when trying to explain what each new term was.  All written in legal ease for all us to enjoy.

I think your both on the same page just reading things a bit different.

If you look at footnote 2 it trys to say dose weigting factors for external whole body dose is 1.

Weighting factors apply to internal dose usually from an uptake unless your looking at medical doses.  In the example you gave above weighting factors would not apply.

hope that helps

sf

   ...perfect...thankyou...

   ..." For the purpose of weighting the external whole body dose (for adding it to the internal dose), a single weighting factor, wT=1.0, has been specified. The use of other weighting factors for external exposure will be approved on a case-by-case basis until such time as specific guidance is issued."


   ...this makes me wonder if they were ever applied to a case-by-case situation and what that might have been...

[wlrun3@aol.com]

 

 ...for cavity decon (floor major dose contribution) the use of two dosimeters (one chest, one thigh) and subsequent calculation of effective dose equivalent would reduce the record dose by fifty percent...

   ...for pressurizer surge line, under rx head, and cono seal shine (overhead major dose contribution) the use of two dosimeters (one chest, one head) and subsequent calculation of effective dose equivalent would not result in a reduction of record dose...

   ...am i right...