Radiation Biology & Protection – MCQs
Radiation Biology & Protection – MCQs
Radiation Biology & Protection – MCQs
1. The latent period in radiation biology is the time between:
a. exposure of film and development
b. subsequent doses of radiation
c. cell rest and cell mitosis
d. exposure to x-radiation and clinical symptoms
e. none of the above
Explanation: The latent period refers to the delay between radiation exposure and the first detectable signs of injury.
2. A free radical:
a. is an uncharged molecule
b. has an unpaired electron in the outer shell
c. is highly reactive and unstable
d. combines with molecules to form toxins
e. all of the above
Explanation: Free radicals are unstable, uncharged molecules with an unpaired electron, making them highly reactive and capable of causing cellular damage.
3. Direct radiation injury occurs when:
a. x-ray photons hit critical targets within a cell
b. x-ray photons pass through the cell
c. x-ray photons are absorbed and form toxins
d. free radicals combine to form toxins
e. none of the above
Explanation: Direct injury happens when radiation hits essential molecules like DNA inside the cell directly.
4. Indirect radiation injury occurs when:
a. x-ray photons hit critical targets within a cell
b. x-ray photons pass through the cell
c. x-ray photons are absorbed and form toxins
d. x-ray photons hit the DNA of a cell
e. none of the above
Explanation: Indirect damage results from the formation of free radicals that later interact with cellular molecules to cause harm.
5. Which of the following relationships describes the response of tissues to radiation?
a. linear
b. linear, threshold
c. linear, nonthreshold
d. nonlinear, nonthreshold
e. none of the above
Explanation: The linear, nonthreshold model suggests any radiation dose, no matter how small, can cause a biological effect.
6. Which of the following factors contributes to radiation injury?
a. total dose
b. dose rate
c. cell sensitivity
d. age
e. all of the above
Explanation: Radiation injury is influenced by all listed factors, including the total dose, rate, type of cells affected, and patient’s age.
7. Which of the following statements is correct?
a. Short-term effects are seen with small amounts of radiation absorbed in a short period.
b. Short-term effects are seen with small amounts of radiation absorbed in a long period.
c. Long-term effects are seen with small amounts of radiation absorbed in a short period.
d. Long-term effects are seen with small amounts of radiation absorbed in a long period.
e. None of the above
Explanation: Long-term effects occur when small amounts of radiation accumulate over time, potentially causing genetic damage or cancer.
8. Radiation injuries that are not seen in the person irradiated but that occur in future generations are termed:
a. somatic effects
b. genetic effects
c. cumulative effects
d. short-term effects
e. long-term effects
Explanation: Genetic effects affect reproductive cells and are passed on to offspring, not seen in the person exposed.
9. Which of the following is most susceptible to ionizing radiation?
a. bone tissue
b. small lymphocyte
c. muscle tissue
d. nerve tissue
e. epithelial tissue
Explanation: The small lymphocyte is the most radiosensitive cell due to its high mitotic rate and lack of specialization.
10. The sensitivity of tissues to radiation is determined by:
a. mitotic activity
b. cell differentiation
c. cell metabolism
d. all of the above
e. none of the above
Explanation: Cells that divide quickly, are less specialized, or have high metabolism are more sensitive to radiation.
11. Which of the following is considered radioresistant?
a. immature reproductive cells
b. young bone cells
c. mature bone cells
d. epithelial cells
e. none of the above
Explanation: Mature bone cells divide infrequently and are thus more resistant to the damaging effects of radiation.
12. An organ that, if damaged, diminishes the quality of an individual’s life is termed a:
a. critical organ
b. somatic organ
c. cumulative organ
d. radioresistant organ
e. none of the above
Explanation: Critical organs are more vulnerable during dental radiography due to their impact on life quality if harmed.
13. The traditional unit for measuring x-ray exposure in air is termed:
a. the gray
b. coulombs per kilogram
c. the rem
d. the rad
e. the roentgen
Explanation: Roentgen is the standard traditional unit for measuring x-ray exposure in air.
14. Which of the following radiation units is determined by the quality factor (QF)?
a. the roentgen
b. the rad
c. the rem
d. the gray
e. coulombs per kilogram
Explanation: Rem accounts for radiation type effects using a quality factor to determine dose equivalent.
15. The unit for measuring the absorption of x-rays is termed:
a. the roentgen
b. the rad
c. the rem
d. quality factor
e. the sievert
Explanation: The rad (or gray in SI units) measures the actual energy absorbed by tissues.
16. Which of the following conversions is correct?
a. 1 R = 2.58 × 10–4 C/kg
b. 1 rad = 0.1 Gy
c. 1 rem = 0.1 Sv
d. 1 Gy = 10 rads
e. 1 Sv = 10 rems
Explanation: The correct SI conversion for exposure is 1 roentgen equals 2.58 × 10⁻⁴ coulombs/kg.
17. Which of the following traditional units does not have an SI equivalent?
a. the roentgen
b. the rad
c. the rem
d. quality factor
e. none of the above
Explanation: Roentgen has no direct SI equivalent for absorbed dose; it’s used for exposure in air only.
18. Which of the following is used only for x-rays?
a. the sievert
b. the gray
c. the rem
d. the rad
e. the roentgen
Explanation: Roentgen is specifically for measuring x-ray and gamma radiation exposure in air.
19. Which of the following conversions is correct?
a. 1 R = 2.58 × 10–4 C/kg
b. 1 Gy = 100 rads
c. 1 Sv = 100 rems
d. 1 rem = rads × QF
e. all of the above
Explanation: All listed conversions are accurate based on SI and traditional radiation units.
20. What is the average dose of background radiation received by an individual in the United States?
a. 0 to 100 mrads (0–0.001 Gy)
b. 50 to 100 mrads (0.0005–0.001 Gy)
c. 150 to 300 mrads (0.0015–0.003 Gy)
d. 200 to 500 mrads (0.002–0.005 Gy)
e. 500 to 1000 mrads (0.005–0.01 Gy)
Explanation: On average, a person in the U.S. receives 150–300 mrads per year from natural background sources.
21. What is the greatest contributor to artificial radiation exposure?
a. radioactive materials
b. medical radiation
c. consumer products
d. weapons production
e. nuclear fuel cycle
Explanation: Medical procedures, including dental radiography, contribute the most to man-made radiation exposure.
22. The amount of radiation exposure an individual receives varies depending on:
a. film speed
b. collimation
c. technique
d. exposure factors
e. all of the above
Explanation: All listed factors influence how much radiation the patient is exposed to during imaging.
23. A single intraoral radiograph (D-speed film, 70 kVp, long PID) results in a mean surface exposure of:
a. 50 mR
b. 250 mR
c. 500 mR
d. 1 R
e. 5 R
Explanation: Using D-speed film, the typical exposure to the patient’s skin for one image is about 250 milliroentgens.
24. What is the dose at which leukemia induction is most likely to occur?
a. 500 mrads (0.005 Gy)
b. 1000 mrads (0.01 Gy)
c. 2000 mrads (0.02 Gy)
d. 5000 mrads (0.05 Gy)
e. none of the above
Explanation: Leukemia is most associated with high radiation doses around 5000 mrads or more.
25. Which of the following statements is incorrect?
a. X-radiation is not harmful to living tissues.
b. Dental radiographs benefit the patient.
c. In dental radiography, the benefit of disease detection outweighs the risk of damage from radiation.
d. Radiography should be prescribed only when the benefit outweighs the risk.
e. Biologic damage results from x-ray exposure.
Explanation: X-radiation is harmful and can damage living tissue, even in small doses.