ARRT Radiation and Safety 2 — Questions and Answers
Question 1: What is the annual occupational effective dose limit for radiation workers in the US?
- 10 mSv
- 20 mSv
- 50 mSv (Correct answer)
- 100 mSv
Correct answer: 50 mSv
The NCRP and NRC set the annual occupational effective dose limit at 50 mSv (5 rem) per year.
Question 2: Which type of radiation has the greatest penetrating power?
- Alpha particles
- Beta particles
- Gamma rays (Correct answer)
- Neutrons
Correct answer: Gamma rays
Gamma rays are highly penetrating electromagnetic radiation requiring dense shielding such as lead or thick concrete.
Question 3: The ALARA principle in radiation protection stands for:
- As Low As Reasonably Achievable (Correct answer)
- Allowable Limits After Radiation Assessment
- Acceptable Levels After Radiation Attenuation
- As Large As Radiation Allows
Correct answer: As Low As Reasonably Achievable
ALARA means As Low As Reasonably Achievable, guiding practitioners to minimize radiation exposure while maintaining image quality.
Question 4: Which device is most commonly used to measure personnel radiation exposure over time?
- Geiger-Müller counter
- Ionization chamber
- OSL dosimeter (Correct answer)
- Scintillation detector
Correct answer: OSL dosimeter
Optically stimulated luminescence (OSL) dosimeters are the standard personnel monitoring device used by radiologic technologists.
Question 5: What shielding material is most commonly used in radiographic rooms due to its high atomic number and density?
- Aluminum
- Concrete
- Lead (Correct answer)
- Steel
Correct answer: Lead
Lead is the standard primary shielding material because its high atomic number (82) and density make it highly effective at attenuating X-rays.
Question 6: Protective lead aprons used in fluoroscopy typically provide an equivalent attenuation of:
- 0.10 mm Pb
- 0.25 mm Pb
- 0.50 mm Pb (Correct answer)
- 1.0 mm Pb
Correct answer: 0.50 mm Pb
Standard lead aprons are rated at 0.50 mm Pb equivalent, providing approximately 88% attenuation of scatter radiation at diagnostic energies.
Question 7: Which of the following is the most radiosensitive tissue according to the law of Bergonié and Tribondeau?
- Muscle cells
- Nerve cells
- Bone marrow cells (Correct answer)
- Mature red blood cells
Correct answer: Bone marrow cells
Bone marrow cells are highly mitotic and undifferentiated, making them among the most radiosensitive tissues in the body.
ARRT Radiation and Safety 2
What is the annual occupational effective dose limit for radiation workers in the US?