NMTCB Radiation Safety & Regulations 3 — Questions and Answers
Question 1: What is the purpose of a 'hot lab' in nuclear medicine?
- Patient imaging room with gamma cameras
- Area for preparation and dispensing of radiopharmaceuticals (Correct answer)
- Storage area for spent radioactive sources
- Location of the cyclotron
Correct answer: Area for preparation and dispensing of radiopharmaceuticals
The hot lab (radiopharmacy) is where radiopharmaceuticals are prepared, assayed, and dispensed under controlled conditions to minimize staff exposure.
Question 2: Which radiation monitoring instrument is best suited for detecting small amounts of radioactive contamination on surfaces?
- Ionization chamber survey meter
- Geiger-Müller (GM) counter (Correct answer)
- Neutron rem meter
- Pressurized ion chamber
Correct answer: Geiger-Müller (GM) counter
GM counters are highly sensitive to low-level contamination and are the instrument of choice for contamination surveys in nuclear medicine.
Question 3: According to ALARA, which action best demonstrates this principle when handling a vial of Tc-99m?
- Using lead-lined syringe shields and minimizing handling time (Correct answer)
- Wearing only gloves without a dosimeter
- Keeping the vial at arm's length without shielding
- Administering the dose as slowly as possible
Correct answer: Using lead-lined syringe shields and minimizing handling time
ALARA (As Low As Reasonably Achievable) is demonstrated by combining shielding, minimizing time, and maximizing distance simultaneously.
Question 4: A nuclear medicine technologist is pregnant. What is the recommended fetal dose equivalent limit per NRC guidelines?
- 0.5 rem (5 mSv) for the entire gestation (Correct answer)
- 5 rem (50 mSv) for the entire gestation
- 0.1 rem (1 mSv) per month
- 1 rem (10 mSv) for the entire gestation
Correct answer: 0.5 rem (5 mSv) for the entire gestation
10 CFR 20.1208 limits the dose to the embryo/fetus to 0.5 rem (5 mSv) once pregnancy is declared.
Question 5: Which type of radiation requires the least shielding material to attenuate?
- Gamma rays
- Beta particles
- Alpha particles (Correct answer)
- X-rays
Correct answer: Alpha particles
Alpha particles are stopped by a sheet of paper or a few centimeters of air, requiring virtually no external shielding.
Question 6: What action must be taken when a radioactive spill occurs in the nuclear medicine department?
- Notify the radiation safety officer, contain the spill, and perform decontamination (Correct answer)
- Immediately call 911 and evacuate the entire building
- Wipe up the spill quickly with a paper towel and discard normally
- Continue working and document the spill at end of shift
Correct answer: Notify the radiation safety officer, contain the spill, and perform decontamination
Spill response requires immediate notification of the RSO, containment to prevent spread, personnel decontamination if needed, and a formal decontamination procedure.
Question 7: What is the half-value layer (HVL) concept used for in radiation shielding calculations?
- Thickness of material needed to reduce radiation intensity by 50% (Correct answer)
- Time required for a radionuclide to decay to half its activity
- Dose at which 50% of an exposed population would die
- Half the distance at which inverse square law applies
Correct answer: Thickness of material needed to reduce radiation intensity by 50%
HVL is the thickness of a specific shielding material that reduces the intensity (or exposure rate) of a radiation beam by 50%.
NMTCB Radiation Safety & Regulations 3
What is the purpose of a 'hot lab' in nuclear medicine?