NMTCB Radiation Safety & Regulations 5 — Questions and Answers
Question 1: What is the correct label category for a radioactive package with a transport index (TI) of 0.8 and surface radiation level of 4 mR/hr?
- Radioactive Yellow-II (Correct answer)
- Radioactive White-I
- Radioactive Yellow-III
- Excepted package
Correct answer: Radioactive Yellow-II
Yellow-II applies when TI is >0 but ≤1 and surface radiation is ≤50 mR/hr; a TI of 0.8 meets these criteria.
Question 2: What is 'committed effective dose equivalent' (CEDE) used to measure?
- Internal radiation dose from inhaled or ingested radionuclides over 50 years (Correct answer)
- Dose received from a single external radiation exposure event
- The total dose a worker receives over their career
- Dose to skin from beta emitters in contact with the body
Correct answer: Internal radiation dose from inhaled or ingested radionuclides over 50 years
CEDE accounts for internal dose from radionuclides deposited in the body, integrated over the 50-year period following intake.
Question 3: After a misadministration (medical event) with a radiopharmaceutical, what is the NRC reporting timeframe?
- Next day notification by telephone, written report within 15 days (Correct answer)
- Immediately by telephone within 1 hour
- Written report only, within 30 days
- Report only to the hospital RSO, no NRC notification required
Correct answer: Next day notification by telephone, written report within 15 days
10 CFR 35.3045 requires next-calendar-day telephone notification to the NRC (or Agreement State) and a written report within 15 days.
Question 4: Lead aprons used in nuclear medicine provide adequate shielding primarily for which type of radiation?
- Low-energy X-rays and gamma rays below ~150 keV (Correct answer)
- High-energy gamma rays above 400 keV
- Beta particles only
- Neutron radiation
Correct answer: Low-energy X-rays and gamma rays below ~150 keV
Lead aprons are effective for low-energy photons but provide minimal protection against high-energy gamma emitters like F-18 (511 keV) commonly used in PET.
Question 5: Which federal regulation mandates radiation training for workers who handle radioactive materials?
- 10 CFR 19.12 (Correct answer)
- 10 CFR 35.60
- 21 CFR 1020
- 49 CFR 172.704
Correct answer: 10 CFR 19.12
10 CFR 19.12 requires licensees to provide radiation protection training to all workers who may be occupationally exposed to radiation.
Question 6: What is the purpose of the 'decay-in-storage' (DIS) method for radioactive waste disposal?
- Allow short-lived radionuclides to decay to background levels before disposal as non-radioactive waste (Correct answer)
- Store waste indefinitely in licensed facilities
- Decay waste until it qualifies as Class B LLW
- Reduce the volume of waste through radioactive decay before incineration
Correct answer: Allow short-lived radionuclides to decay to background levels before disposal as non-radioactive waste
DIS allows short-lived radionuclides (typically ≤120 days half-life) to decay to background levels so waste can be disposed of as ordinary trash.
Question 7: Which radiation quality factor (Q) is assigned to gamma rays and X-rays for radiation weighting purposes?
- 1 (Correct answer)
- 5
- 10
- 20
Correct answer: 1
Gamma rays and X-rays have a radiation weighting factor (wR) of 1, meaning their equivalent dose equals the absorbed dose in gray.
NMTCB Radiation Safety & Regulations 5
What is the correct label category for a radioactive package with a transport index (TI) of 0.8 and surface radiation level of 4 mR/hr?