RSO Dosimetry and Personal Exposure Assessment 2

Question 1

The shallow dose equivalent (SDE) on a personnel dosimeter measures dose at a tissue depth of:

Accepted Answer

0.007 cm (70 µm)

Answer

Shallow dose equivalent represents the dose at 0.007 cm (70 micrometers) depth in tissue, representing the basal layer of skin and used to assess skin dose from beta and low-energy photon radiation.

Question 2

A personnel dosimeter reading must be investigated when it exceeds what percentage of the applicable dose limit according to NRC guidance?

Accepted Answer

25%

Answer

NRC guidance recommends that doses exceeding 25% of the applicable dose limit trigger investigation to determine the cause and ensure limits are not exceeded.

Question 3

To estimate effective dose when using two dosimeters (collar outside apron, waist under apron) during fluoroscopy, the NCRP formula uses:

Accepted Answer

0.025 × collar + 0.5 × waist (or similar weighting formula)

Answer

Weighted formulas such as E = 0.025 × H_collar + 0.5 × H_waist are used to estimate effective dose from two dosimeter readings during fluoroscopic procedures with lead aprons.

Question 4

A radiation worker's finger ring dosimeter shows 1,500 mrem for the month. The NRC quarterly limit for extremity dose is:

Accepted Answer

12,500 mrem (part of 50 rem/year extremity limit)

Answer

The NRC annual extremity dose limit is 50 rem (500 mSv); divided equally over four quarters, the quarterly limit is approximately 12,500 mrem (12.5 rem).

Question 5

Internal dose assessment via bioassay is required when a worker's intake of radioactive material could result in a committed effective dose exceeding:

Accepted Answer

10 mSv (1 rem)

Answer

NRC regulations (10 CFR 20.1502) require monitoring internal exposure when an individual is likely to receive an annual intake resulting in a committed effective dose exceeding 10% of the annual limit, which is 10% of 50 mSv = 5 mSv; however, many RSOs use 10 mSv (1 rem) as a practical investigation threshold.

RSO - Radiation Safety Officer Practice Test

RSO - Radiation Safety Officer Practice Test

RSO Dosimetry and Personal Exposure Assessment 2