DPT Radiation Dose — MFDS Part 1 MCQ

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ModerateRadiologyDPT Radiation DoseMFDS Part 1

A typical adult dental panoramic tomograph (DPT) delivers an effective dose of approximately 0.01 mSv. Using an average UK natural background radiation dose of 2.2 mSv per year, this is approximately equivalent to how much natural background radiation?

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Correct answer: B — 1–3 days

The correct answer is B. A typical adult DPT/OPG effective dose of 0.01 mSv can be converted using the average UK background dose: (0.01 ÷ 2.2) × 365 = approximately 1.7 days. This lies within the 1–3 day range. Actual doses vary with the equipment, exposure settings and patient size, so this is a representative comparison rather than an exact value. One hour and 30 seconds are far too short, while 6 months and 1 year would represent effective doses hundreds of times greater than that of a typical panoramic radiograph.

Reference: Dorset County Hospital NHS Foundation Trust, Medical Physics Department. X-Ray Imaging Procedures: Background Dose Equivalents, version 6.0, 2024. https://www.dchft.nhs.uk/wp-content/uploads/2026/04/6-2024-Background-Dose-Equivalents-Information-for-display-GENERAL-V6.pdf