Answer to Question #12114 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Personnel Monitoring (PM)

The following question was answered by an expert in the appropriate field:

Q

For a single thermoluminescent dosimeter (TLD) worn at the collar level outside the lead apron, is there a formula to evaluate the effective dose (similar to Webster's method)?

A

For a full explanation, I would recommend you read the National Council on Radiation Protection and Measurements (NCRP) Report No. 122 Use of Personal Monitors to Estimate Effective Dose Equivalent and Effective Dose to Workers for External Exposure to Low-LET Radiation.

For a brief explanation, NCRP provides correction factors to obtain effective dose equivalent in situations when dosimetry (like TLDs) is worn and a lead apron is worn. The goal is to calculate a better estimate of whole-body radiation dose to the worker, because an apron provides good protection for the torso and the dosimeter reading likely doesn't represent the actual dose very well.

If a single dosimeter is worn at the collar outside the apron, you can divide the dosimeter reading by 5.6 to obtain effective dose equivalent.

If a dosimeter is worn at the waist under an apron and a dosimeter is worn at the collar outside the apron, effective dose equivalent is calculated by multiplying 1.5 times the waist dosimeter reading plus 0.04 times the collar dosimeter reading.

Kelly Classic
Certified Medical Health Physicist

Reference

National Council on Radiation Protection and Measurements. Use of personal monitors to estimate effective dose equivalent and effective dose to workers for external exposure to low-LET radiation. Report No. 122; 1995. Available at: ncrponline.org/publications/reports/ncrp-reports-122/. Accessed 23 August 2017.

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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