ADAT Dental Radiology & Imaging 2 — Questions and Answers
Question 1: What is the primary source of occupational radiation exposure for dental professionals during patient radiography?
- Primary radiation from the X-ray tube
- Scatter (secondary) radiation from the patient (Correct answer)
- Leakage radiation from the X-ray unit casing
- Background cosmic radiation
Correct answer: Scatter (secondary) radiation from the patient
Scatter radiation generated as the primary beam interacts with the patient is the principal source of occupational exposure for dental personnel standing nearby.
Question 2: Which radiographic modality provides the broadest single-image survey of the entire maxillofacial region, including all teeth, alveolar bone, and the TMJ?
- Full-mouth periapical series
- Panoramic radiograph (Correct answer)
- Lateral cephalometric radiograph
- Maxillary occlusal radiograph
Correct answer: Panoramic radiograph
Panoramic (orthopantomogram) radiography uses a rotating X-ray source and receptor to capture the entire maxillofacial skeleton, dentition, and TMJ on one extraoral image.
Question 3: What fundamental advantage does Cone Beam Computed Tomography (CBCT) offer over conventional 2D dental radiographs?
- Real-time fluoroscopic visualization
- Three-dimensional volumetric imaging data (Correct answer)
- Greater reduction in radiation dose
- Color differentiation of dental hard tissues
Correct answer: Three-dimensional volumetric imaging data
CBCT acquires a volumetric data set that can be reconstructed in any plane (axial, coronal, sagittal), providing 3D anatomical detail unavailable on conventional 2D radiographs.
Question 4: Which is the earliest radiographic sign of a developing periapical abscess?
- A well-defined corticated radiolucency at the apex
- Widening of the apical periodontal ligament space (Correct answer)
- Condensing osteitis surrounding the root apex
- Loss of the lamina dura around the entire root
Correct answer: Widening of the apical periodontal ligament space
Acute periapical inflammation initially causes edema that widens the apical PDL space before sufficient bone resorption accumulates to create a distinct periapical radiolucency.
Question 5: Which filtration material is most commonly added to dental X-ray units to remove low-energy, long-wavelength photons that would only increase patient dose?
- Lead
- Copper
- Aluminum (Correct answer)
- Stainless steel
Correct answer: Aluminum
Aluminum filters selectively absorb soft, low-energy X-rays that cannot penetrate tissues to form a diagnostic image but would otherwise be absorbed by superficial patient tissues.
Question 6: Where should a dental operator stand during X-ray exposure if no protective barrier is available?
- Directly behind the X-ray tubehead
- At 90–135 degrees to the primary beam, at least 6 feet from the patient (Correct answer)
- Immediately behind the patient's head
- Beside the patient's shoulder to hold the receptor
Correct answer: At 90–135 degrees to the primary beam, at least 6 feet from the patient
Standing at a 90–135 degree angle to the primary beam and at least 6 feet away places the operator outside the primary beam path and away from the highest scatter intensity.
Question 7: Which type of digital radiography system uses a reusable flexible phosphor storage plate that is read by a laser scanner?
- Charge-coupled device (CCD)
- Complementary metal-oxide semiconductor (CMOS)
- Photostimulable phosphor (PSP) (Correct answer)
- Direct flat-panel detector
Correct answer: Photostimulable phosphor (PSP)
PSP (photostimulable phosphor) plates store a latent image after X-ray exposure and are read by a laser in a dedicated scanner, then erased and reused.
ADAT Dental Radiology & Imaging 2
What is the primary source of occupational radiation exposure for dental professionals during patient radiography?