CHP Radiation Protection Principles 2 — Questions and Answers
Question 1: The linear no-threshold (LNT) model assumes which of the following about radiation risk at low doses?
- Risk is zero below a threshold dose
- Risk increases linearly with dose starting from zero (Correct answer)
- Risk follows a quadratic relationship with dose
- Risk is hormetic at low doses
Correct answer: Risk increases linearly with dose starting from zero
The LNT model postulates that cancer risk is directly proportional to dose with no safe threshold, even at very low doses.
Question 2: Which quantity is used to compare the biological effectiveness of different types of radiation on a specific tissue?
- Absorbed dose (Gy)
- Equivalent dose (Sv) (Correct answer)
- Effective dose (Sv)
- Kerma (Gy)
Correct answer: Equivalent dose (Sv)
Equivalent dose accounts for radiation type by multiplying absorbed dose by the radiation weighting factor (wR).
Question 3: A worker receives 150 mrem to the hands and 5 mrem whole-body dose. Which limit is most relevant to assess?
- Whole-body effective dose limit of 5 rem/year
- Extremity dose limit of 50 rem/year (Correct answer)
- Lens of eye limit of 15 rem/year
- Declared pregnant worker limit of 0.5 rem/9 months
Correct answer: Extremity dose limit of 50 rem/year
Extremity (hands, feet, elbows, knees) have a separate NRC annual limit of 50 rem (500 mSv), which governs this exposure.
Question 4: What is the primary purpose of a radiological survey meter calibration?
- To extend the instrument's battery life
- To ensure accuracy of dose rate measurements against a traceable standard (Correct answer)
- To clean the detector chamber of contamination
- To update the firmware of digital detectors
Correct answer: To ensure accuracy of dose rate measurements against a traceable standard
Calibration verifies instrument response against a known source traceable to national standards (NIST), ensuring measurement accuracy.
Question 5: In the ALARA principle, which of the following is NOT one of the three primary factors considered?
- Time
- Shielding
- Distance
- Dose rate alarm threshold (Correct answer)
Correct answer: Dose rate alarm threshold
ALARA practice uses time, distance, and shielding as the three fundamental tools to reduce radiation exposure.
Question 6: A radiation worker's occupational dose limit under 10 CFR 20 for the whole body is:
- 1 rem per year
- 5 rem per year (Correct answer)
- 10 rem per year
- 50 rem per year
Correct answer: 5 rem per year
10 CFR 20.1201 sets the occupational total effective dose equivalent (TEDE) limit at 5 rem (50 mSv) per year.
Question 7: Which type of dosimeter provides an immediate real-time readout of accumulated dose?
- Thermoluminescent dosimeter (TLD)
- Film badge
- Optically stimulated luminescence (OSL) dosimeter
- Electronic personal dosimeter (EPD) (Correct answer)
Correct answer: Electronic personal dosimeter (EPD)
EPDs provide instantaneous digital dose and dose rate readouts, unlike passive dosimeters (TLD, OSL, film) which require laboratory processing.
CHP Radiation Protection Principles 2
The linear no-threshold (LNT) model assumes which of the following about radiation risk at low doses?