MFDS Radiology and Radiography

Question 1

According to the IRMER (Ionising Radiation (Medical Exposure) Regulations 2017) in the UK, what are the three key roles defined in the regulations for dental radiography?

Accepted Answer

Referrer (who requests the exposure), practitioner (who justifies the exposure), and operator (who carries out the practical aspects)

Answer

Patient, radiographer, and consultant

Answer

Dentist, nurse, and technician

Answer

Inspector, supervisor, and operator

Question 2

What is the ALARA (or ALARP) principle in dental radiology and how is it applied in practice?

Accepted Answer

As Low As Reasonably Achievable (or Practicable) — radiation doses should be kept to the minimum consistent with obtaining diagnostic information, achieved through proper selection criteria, optimal technique, quality assurance, and rectangular collimation

Answer

All Lateral And Rotational Adjustments — it refers to patient positioning

Answer

Anterior Lateral Anteroposterior Radiograph Assessment — a specific projection technique

Answer

It refers to the storage protocol for radiographic films

Question 3

On a periapical radiograph, a well-defined radiolucent area is visible at the apex of a vital upper central incisor with a thin radiopaque border. What is the most likely diagnosis?

Accepted Answer

Nasopalatine duct cyst (incisive canal cyst)

Answer

Periapical abscess

Answer

Periapical (radicular) cyst

Answer

Periapical granuloma

Question 4

What radiographic features would suggest a lesion in the jaw is malignant rather than benign?

Accepted Answer

Ill-defined, irregular, ragged margins with no corticated border, destruction of adjacent structures (teeth, cortical bone, inferior alveolar canal), and a 'moth-eaten' or permeative pattern of bone destruction

Answer

Well-defined margins with a corticated border

Answer

A perfectly round radiolucent area with a sclerotic rim

Answer

A mixed radiolucent-radiopaque lesion with a clear capsule

Question 5

What is the maximum recommended dose of radiation for occupational exposure per year for dental professionals in the UK, according to the Ionising Radiations Regulations 2017 (IRR17)?

Accepted Answer

20 mSv per year (whole body effective dose limit for classified workers)

Answer

1 mSv per year

Answer

50 mSv per year

Answer

100 mSv per year

Question 6

What is the advantage of a cone beam computed tomography (CBCT) scan over conventional two-dimensional radiography in dentistry, and what are its limitations?

Accepted Answer

CBCT provides three-dimensional imaging allowing assessment of structures in all planes, with higher spatial resolution than medical CT for dental structures; limitations include higher radiation dose than conventional radiographs, limited soft tissue contrast, and motion artefacts

Answer

CBCT uses less radiation than a single periapical radiograph and has no limitations

Answer

CBCT is identical to medical CT in all respects

Answer

CBCT only shows soft tissues and cannot image bone or teeth