Answer to Question #12088 Submitted to "Ask the Experts"

Category: Radiation Workers

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


Can you explain what the EDE1 and EDE2 corrections for film badges that are used with lead aprons mean? Why wouldn't some states accept this method?


For a full explanation, I would recommend you read 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 when dosimetry is worn and a lead apron is worn to obtain effective dose equivalent (EDE). 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 EDE.

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

Some states do allow this correction. I live in Minnesota and the regulations are written such that the annual limits for a radiation worker are in EDE units. So they allow it, but we do need to keep all records of what we have done.

If you are unsure if your state allows it, a close reading of the regulations for the wording in the worker limits section could help. Or you could just call your state agency.

Kelly Classic
Certified Medical Health Physicist


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. Bethesda, Maryland: National Council on Radiation Protection and Measurements; NCRP Report 122; 1995.

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