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Ultrasound frequency and resolution — FRCA Primary MCQ

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HardPhysics and Clinical MeasurementUltrasound frequency and resolutionFRCA Primary

When a superficial vessel is imaged with a 12 MHz rather than 5 MHz ultrasound probe, what change is expected?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Higher spatial resolution with reduced tissue penetration

The best answer is “Higher spatial resolution with reduced tissue penetration”. Higher-frequency ultrasound has a shorter wavelength and improves spatial resolution, but it is attenuated more rapidly and therefore penetrates less deeply. This trade-off makes high-frequency linear probes useful for superficial vessels and nerves. The alternatives each deny or reverse part of that frequency-dependent trade-off.

Reference: RCoA, Primary FRCA Syllabus: https://rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf