Imaging physics: Compton scatter: 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: Compton scatter

Sample item

In the diagnostic energy range, which interaction is the principal source of scattered radiation that reaches the operator and degrades the image?

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

The answer and the reasoning

A. Compton scattering

In Compton scattering a photon strikes an outer-shell electron and is deflected with reduced energy. The deflected photon causes film fog and staff exposure. It depends on electron density and is almost independent of atomic number.

Option by option

  • A. Compton scattering (correct)

    Correct. Compton scatter produces the scattered photons seen in practice.

  • B. Photoelectric effect

    The photoelectric effect absorbs the photon entirely and produces no scattered photon.

  • C. Coherent scattering with complete absorption

    Complete absorption does not give scatter.

  • D. Pair production

    Pair production needs photon energy above 1.02 MeV, beyond diagnostic range.

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 A, Compton scattering. In Compton scattering a photon strikes an outer-shell electron and is deflected with reduced energy.

Why is "Photoelectric effect" not the answer?

The photoelectric effect absorbs the photon entirely and produces no scattered photon.

Why is "Coherent scattering with complete absorption" not the answer?

Complete absorption does not give scatter.

Why is "Pair production" not the answer?

Pair production needs photon energy above 1.02 MeV, beyond diagnostic range.

What concept does this question test?

It tests Imaging physics: Compton scatter in Radiology. The deflected photon causes film fog and staff exposure. It depends on electron density and is almost independent of atomic number.

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: Compton scatter?

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.