Radiation safety and radiobiology: radiation weighting factor: 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 · Radiation safety and radiobiology: radiation weighting factor

Sample item

Lung tissue receives an absorbed dose of 1 Gy from alpha particles in one patient and 1 Gy from X-rays in another. How do the equivalent doses compare?

AAlpha: 1 Sv, X-rays: 20 SvBAlpha: 1 Sv, X-rays: 1 SvCAlpha: 20 Sv, X-rays: 1 SvDAlpha: 5 Sv, X-rays: 1 Sv

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

The answer and the reasoning

C. Alpha: 20 Sv, X-rays: 1 Sv

Equivalent dose equals absorbed dose multiplied by the radiation weighting factor. The factor is 1 for X-rays and gamma rays and 20 for alpha particles, because densely ionising radiation does more biological damage per gray.

Option by option

A. Alpha: 1 Sv, X-rays: 20 Sv
This reverses the weighting factors of the two radiation types.
B. Alpha: 1 Sv, X-rays: 1 Sv
Equal weighting would ignore the greater biological effect of alpha particles.
C. Alpha: 20 Sv, X-rays: 1 Sv (correct)
Correct. Alpha particles have a weighting factor of 20 and X-rays have 1.
D. Alpha: 5 Sv, X-rays: 1 Sv
A weighting factor of 5 applies to certain neutron energies, not to alpha particles.

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, Alpha: 20 Sv, X-rays: 1 Sv. Equivalent dose equals absorbed dose multiplied by the radiation weighting factor.

Why is "Alpha: 1 Sv, X-rays: 20 Sv" not the answer?

This reverses the weighting factors of the two radiation types.

Why is "Alpha: 1 Sv, X-rays: 1 Sv" not the answer?

Equal weighting would ignore the greater biological effect of alpha particles.

Why is "Alpha: 5 Sv, X-rays: 1 Sv" not the answer?

A weighting factor of 5 applies to certain neutron energies, not to alpha particles.

What concept does this question test?

It tests Radiation safety and radiobiology: radiation weighting factor in Radiology. The factor is 1 for X-rays and gamma rays and 20 for alpha particles, because densely ionising radiation does more biological damage per gray.

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 Radiation safety and radiobiology: radiation weighting factor?

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.