Radiotherapy: Bragg peak: 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 · Radiotherapy: Bragg peak

Sample item

What property of proton beam therapy makes it attractive for tumours adjacent to critical structures, such as in children?

AGreater scatter than photonsBA skin-sparing build-up regionCBragg peak with minimal exit dose beyond the tumourDUniform dose along the entire path

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

The answer and the reasoning

C. Bragg peak with minimal exit dose beyond the tumour

Heavy charged particles deposit most of their energy at a defined depth (the Bragg peak) with almost no dose beyond. This spares normal tissue distal to the target, and reduces integral dose and secondary malignancy risk. Photons deposit dose all along the path and beyond the target.

Option by option

A. Greater scatter than photons
Protons have less lateral scatter, not more.
B. A skin-sparing build-up region
Skin sparing is a feature of megavoltage photons, not specific to protons.
C. Bragg peak with minimal exit dose beyond the tumour (correct)
Correct. The Bragg peak limits exit dose.
D. Uniform dose along the entire path
Protons do not deliver uniform dose along their path.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is C, Bragg peak with minimal exit dose beyond the tumour. Heavy charged particles deposit most of their energy at a defined depth (the Bragg peak) with almost no dose beyond.

Why is "Greater scatter than photons" not the answer?

Protons have less lateral scatter, not more.

Why is "A skin-sparing build-up region" not the answer?

Skin sparing is a feature of megavoltage photons, not specific to protons.

Why is "Uniform dose along the entire path" not the answer?

Protons do not deliver uniform dose along their path.

What concept does this question test?

It tests Radiotherapy: Bragg peak in Radiology. This spares normal tissue distal to the target, and reduces integral dose and secondary malignancy risk. Photons deposit dose all along the path and beyond the target.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Radiotherapy: Bragg peak?

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.