NMTCB Radiation Safety & Regulations 2 — Questions and Answers
Question 1: What is the annual occupational effective dose limit for radiation workers in the US?
- 5 rem (50 mSv) (Correct answer)
- 1 rem (10 mSv)
- 2 rem (20 mSv)
- 10 rem (100 mSv)
Correct answer: 5 rem (50 mSv)
The NRC sets the annual occupational effective dose limit at 5 rem (50 mSv) per year for radiation workers.
Question 2: Which principle of radiation protection involves maximizing distance from the source?
- Time
- Distance (Correct answer)
- Shielding
- Containment
Correct answer: Distance
Distance is one of the three cardinal principles of radiation protection; doubling distance reduces exposure by a factor of four (inverse square law).
Question 3: A radiation survey meter reads 5 mR/hr at 1 meter from a source. What is the approximate dose rate at 2 meters?
- 1.25 mR/hr (Correct answer)
- 2.5 mR/hr
- 10 mR/hr
- 20 mR/hr
Correct answer: 1.25 mR/hr
By the inverse square law, doubling the distance reduces dose rate by a factor of 4, so 5 ÷ 4 = 1.25 mR/hr.
Question 4: Which document establishes radiation protection standards for NRC-licensed facilities?
- 10 CFR Part 20 (Correct answer)
- 21 CFR Part 11
- 49 CFR Part 173
- 29 CFR Part 1910
Correct answer: 10 CFR Part 20
10 CFR Part 20 (Standards for Protection Against Radiation) is the NRC regulation governing occupational and public radiation exposure.
Question 5: What type of dosimeter provides a continuous, real-time readout of accumulated radiation dose?
- Film badge
- TLD badge
- Electronic personal dosimeter (EPD) (Correct answer)
- OSL dosimeter
Correct answer: Electronic personal dosimeter (EPD)
Electronic personal dosimeters (EPDs) provide real-time digital readout of accumulated dose and dose rate, unlike passive dosimeters.
Question 6: Which radioactive waste classification applies to most low-level radioactive waste generated in nuclear medicine?
- Class A (Correct answer)
- Class B
- Class C
- High-level waste
Correct answer: Class A
Most nuclear medicine waste (short half-life isotopes at low concentrations) is classified as Class A low-level radioactive waste, the least restrictive category.
Question 7: What is the NRC-mandated lens of the eye annual dose equivalent limit for occupational workers?
- 15 rem (150 mSv) (Correct answer)
- 5 rem (50 mSv)
- 50 rem (500 mSv)
- 25 rem (250 mSv)
Correct answer: 15 rem (150 mSv)
The NRC sets the occupational lens of the eye dose equivalent limit at 15 rem (150 mSv) per year under 10 CFR 20.1201.
NMTCB Radiation Safety & Regulations 2
What is the annual occupational effective dose limit for radiation workers in the US?