ORE Part 1 Radiology & Radiation Protection 2

Question 1

What is the purpose of a 'dental panoramic tomograph' (DPT/OPG) compared to periapical radiographs?

Accepted Answer

DPT provides a broad overview of the dentition, alveolar bone, mandible, and TMJ in a single image but with less detail; periapicals provide superior detail of individual teeth and periapical areas

Answer

DPT (Panoramic/OPG) provides a single overview image of the full dentition, alveolar bone, sinuses, and TMJ regions — useful for initial assessments, impacted teeth, and pathology screening. Periapicals offer superior detail for individual teeth and periapical regions.

Question 2

What is the 'dead man's handle' (deadman switch) concept in dental radiography?

Accepted Answer

The X-ray exposure switch must be actively held by the operator — releasing it automatically stops exposure, preventing accidental prolonged radiation release

Answer

The deadman switch (non-latching exposure switch) ensures the operator must actively maintain pressure throughout exposure. Releasing the switch immediately terminates exposure, preventing accidental prolonged irradiation.

Question 3

What is the recommended minimum distance the operator should stand from the X-ray tube head during exposure?

Accepted Answer

At least 1.5–2 metres away, outside the primary beam, ideally behind a lead screen or wall

Answer

Operators should stand at least 1.5–2 metres from the tube head, outside the primary beam (not at 90° to it), and ideally behind a structural barrier during dental X-ray exposures.

Question 4

What is the significance of a 'cone beam CT' (CBCT) scan in dental practice compared to conventional dental X-rays?

Accepted Answer

CBCT provides 3D volumetric imaging but delivers significantly higher radiation dose than 2D dental radiographs — use must be justified by need for 3D information unavailable from conventional imaging

Answer

CBCT provides three-dimensional imaging crucial for implant planning, surgical anatomy, and complex endodontics. However, the effective dose is significantly higher than conventional dental radiographs (approximately 40–500 µSv), requiring strict justification.

Question 5

What is 'fog' on a dental radiograph and what causes it?

Accepted Answer

Overall grey, low-contrast appearance caused by: light leakage in darkroom, expired film, improper processing, or secondary/scatter radiation reaching the film

Answer

Radiographic fog is a general increase in film density reducing contrast and diagnostic quality. Causes include: secondary/scatter radiation, light leaks, outdated film, improper processing temperatures, or chemical contamination.

ORE Part 1 Practice Test

ORE Part 1 Practice Test

ORE Part 1 Radiology & Radiation Protection 2