Dental Radiology Flashcards

According to UK IRMER regulations, which professional is responsible for justifying a dental radiograph?

Answer: The referrer or practitioner (usually the dentist)

Under the Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R), the practitioner is responsible for justifying each radiographic exposure. In dentistry, this is typically the dentist who must ensure that each radiograph provides a net benefit to the patient and cannot be replaced by a non-ionising alternative.

What is the recommended interval for routine bitewing radiographs in a high-caries-risk adult patient?

Answer: Every 6 months

FGDP(UK) Selection Criteria for Dental Radiography recommends posterior bitewing radiographs at 6-monthly intervals for high-caries-risk adults. For moderate risk, the interval is 12–18 months, and for low risk, 24 months. This is based on the expected rate of caries progression.

Which radiographic view is most appropriate for assessing a suspected fracture of the mandibular condyle?

Answer: Dental panoramic tomograph (DPT/OPG)

The DPT (OPG) provides a comprehensive view of both condyles, the entire mandible, and related structures in a single image. It is the first-line radiograph for suspected mandibular fractures. CBCT or CT may be used for further assessment of complex condylar fractures.

What does the ALARP principle stand for in dental radiography?

Answer: As Low As Reasonably Practicable

ALARP stands for As Low As Reasonably Practicable. It is the UK regulatory principle requiring that radiation doses be kept as low as is reasonably practicable while still obtaining diagnostically adequate images. This includes using rectangular collimation, correct exposure settings, and digital sensors where possible.

Rectangular collimation of the X-ray beam reduces patient radiation dose by approximately what percentage compared to round collimation?

Answer: 50–60%

Rectangular collimation reduces the irradiated tissue volume by approximately 50–60% compared to a standard round cone, significantly reducing patient dose. It restricts the beam to match the size of the receptor (film or sensor), eliminating unnecessary exposure of surrounding tissues.

On a periapical radiograph, a well-defined radiolucency at the apex of a non-vital tooth is most likely to represent which pathology?

Answer: Periapical granuloma or cyst

A well-defined radiolucency at the apex of a non-vital tooth most commonly represents a periapical granuloma (most frequent) or periapical (radicular) cyst. Differentiation between granuloma and cyst cannot be made radiographically alone and requires histopathological examination.