Imaging physics: image noise and dose: 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.

Try it

Radiology · Imaging physics: image noise and dose

Sample item

On a CT scan, the image of an obese patient looks grainy. Which adjustment reduces quantum noise?

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

The answer and the reasoning

C. Increasing the tube current-time product (mAs)

Quantum noise depends on the number of photons reaching the detector, so more mAs lowers noise at the cost of a higher patient dose. This trade-off is balanced with the ALARA principle.

Option by option

  • A. Narrowing the window width

    Window width alters display and does not change the acquired noise.

  • B. Using a smaller matrix only

    A smaller matrix does not address photon statistics.

  • C. Increasing the tube current-time product (mAs) (correct)

    Correct. More photons give a less noisy image but a higher dose.

  • D. Decreasing the mAs

    Decreasing mAs would increase noise.

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.

More Radiology questions

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is C, Increasing the tube current-time product (mAs). Quantum noise depends on the number of photons reaching the detector, so more mAs lowers noise at the cost of a higher patient dose.

Why is "Narrowing the window width" not the answer?

Window width alters display and does not change the acquired noise.

Why is "Using a smaller matrix only" not the answer?

A smaller matrix does not address photon statistics.

Why is "Decreasing the mAs" not the answer?

Decreasing mAs would increase noise.

What concept does this question test?

It tests Imaging physics: image noise and dose in Radiology. This trade-off is balanced with the ALARA principle.

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 physics: image noise and dose?

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.