DRC Risk Assessment & Mitigation 3 — Questions and Answers
Question 1: Which body tissue has the HIGHEST radiosensitivity among the following options?
- Muscle tissue
- Nerve tissue
- Bone marrow (Correct answer)
- Dental enamel
Correct answer: Bone marrow
Bone marrow is highly radiosensitive because it contains rapidly dividing hematopoietic stem cells that are actively producing blood cells.
Question 2: A cone beam CT (CBCT) scan delivers significantly more radiation than a periapical radiograph. Under what circumstance is CBCT justified in a risk assessment framework?
- When the patient or referring dentist requests it
- When conventional 2D imaging cannot provide sufficient diagnostic information for the clinical question (Correct answer)
- Routinely for all new patients to obtain a comprehensive baseline
- When the clinician wants to reduce the number of individual periapical films taken
Correct answer: When conventional 2D imaging cannot provide sufficient diagnostic information for the clinical question
CBCT is justified only when 3D information is necessary and cannot be obtained from conventional 2D imaging, given its substantially higher patient dose.
Question 3: The effective dose concept in radiation protection accounts for which of the following?
- Only the energy deposited in directly irradiated tissue
- The absorbed dose weighted for tissue radiosensitivity and radiation type (Correct answer)
- The total number of X-ray photons produced by the tube
- The distance between the patient and the X-ray source
Correct answer: The absorbed dose weighted for tissue radiosensitivity and radiation type
Effective dose applies tissue-weighting factors to absorbed doses in different organs, allowing comparison of risk across different exposure scenarios.
Question 4: Which radiographic examination carries the highest effective radiation dose?
- Single periapical film (digital)
- Four bitewing radiographs (digital)
- Panoramic radiograph
- Full-mouth series (18 films, digital) (Correct answer)
Correct answer: Full-mouth series (18 films, digital)
A full-mouth series of 18 digital images delivers the highest cumulative effective dose among routine dental radiographic surveys.
Question 5: A patient presents who is breastfeeding. What special radiographic precaution is required?
- No radiographs should be taken during the breastfeeding period
- Standard lead apron and thyroid collar are sufficient; no additional precautions are needed (Correct answer)
- Radiographs must be delayed at least 24 hours after the last feeding
- Only panoramic radiographs are permitted for breastfeeding patients
Correct answer: Standard lead apron and thyroid collar are sufficient; no additional precautions are needed
Dental X-rays do not affect breast milk, so standard shielding protocols are all that is required for breastfeeding patients.
Question 6: What is the primary purpose of a lead apron during dental radiography?
- To protect the patient's eyes from scattered radiation
- To protect the gonads and abdominal organs from scattered radiation (Correct answer)
- To reduce the X-ray exposure time needed for adequate density
- To prevent primary beam radiation from reaching the patient's head
Correct answer: To protect the gonads and abdominal organs from scattered radiation
The lead apron attenuates scatter radiation directed toward the gonads and abdominal organs, protecting radiosensitive tissues outside the primary beam.
Question 7: A dental hygienist is evaluating whether bitewing radiographs are needed for a low-caries-risk adult patient with excellent oral hygiene and no clinical signs of decay. The ADA/FDA guidelines suggest:
- Bitewings every 6 months regardless of risk
- Bitewings every 18 to 36 months based on clinical judgment (Correct answer)
- No bitewings are ever indicated for low-risk adults
- Bitewings every 12 months as a minimum standard of care
Correct answer: Bitewings every 18 to 36 months based on clinical judgment
ADA/FDA selection criteria recommend posterior bitewings every 18 to 36 months for low-caries-risk adult patients.
DRC Risk Assessment & Mitigation 3
Which body tissue has the HIGHEST radiosensitivity among the following options?