Imaging modalities and physics: CT motion artefact timing: 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: CT motion artefact timing

Sample item

A breathless patient moves during a CT of the chest, and images show double contours of the diaphragm and vessels. Which scanner change is the most effective in reducing this?

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

The answer and the reasoning

D. Faster gantry rotation and higher pitch

Motion artefact is a function of the time taken to acquire data. Faster rotation and a higher pitch shorten the scan, so less movement occurs during acquisition. Breath-hold instructions help as well.

Option by option

  • A. Increasing the field of view

    A larger field of view changes pixel size, not motion blur.

  • B. Lower kVp

    Lower kVp changes contrast and dose but does not shorten the scan.

  • C. Thicker slices with a smoother kernel only

    Slice thickness and kernel do not fix movement between rotations.

  • D. Faster gantry rotation and higher pitch (correct)

    Correct. A shorter acquisition time freezes motion better.

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, Faster gantry rotation and higher pitch. Motion artefact is a function of the time taken to acquire data.

Why is "Increasing the field of view" not the answer?

A larger field of view changes pixel size, not motion blur.

Why is "Lower kVp" not the answer?

Lower kVp changes contrast and dose but does not shorten the scan.

Why is "Thicker slices with a smoother kernel only" not the answer?

Slice thickness and kernel do not fix movement between rotations.

What concept does this question test?

It tests Imaging modalities and physics: CT motion artefact timing in Radiology. Faster rotation and a higher pitch shorten the scan, so less movement occurs during acquisition. Breath-hold instructions help as well.

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: CT motion artefact timing?

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.