Imaging modalities and physics: ultrasound frequency and attenuation: practice question

A Radiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Radiology · Imaging modalities and physics: ultrasound frequency and attenuation

Sample item

A sonographer changes from a 3.5 MHz curvilinear probe to a 12 MHz linear probe for a superficial lump. What is the effect on the image?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Better axial resolution but less penetration

A higher frequency has a shorter wavelength and a shorter pulse, giving better axial resolution. It is also attenuated faster, so depth of penetration falls, which makes high-frequency probes suitable for superficial structures.

Option by option

  • A. No change in resolution since frequency affects only brightness

    Frequency strongly affects resolution through pulse length.

  • B. Better penetration but poorer axial resolution

    This describes a lower frequency, not a higher one.

  • C. Better resolution and better penetration

    Resolution and penetration trade off against each other as frequency changes.

  • D. Better axial resolution but less penetration (correct)

    Correct. High frequency improves detail but is absorbed more quickly.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, Better axial resolution but less penetration. A higher frequency has a shorter wavelength and a shorter pulse, giving better axial resolution.

Why is "No change in resolution since frequency affects only brightness" not the answer?

Frequency strongly affects resolution through pulse length.

Why is "Better penetration but poorer axial resolution" not the answer?

This describes a lower frequency, not a higher one.

Why is "Better resolution and better penetration" not the answer?

Resolution and penetration trade off against each other as frequency changes.

What concept does this question test?

It tests Imaging modalities and physics: ultrasound frequency and attenuation in Radiology. It is also attenuated faster, so depth of penetration falls, which makes high-frequency probes suitable for superficial structures.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Imaging modalities and physics: ultrasound frequency and attenuation?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.