Radiotherapy and nuclear medicine basics: reoxygenation: 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 · Radiotherapy and nuclear medicine basics: reoxygenation

Sample item

Hypoxic cells in the centre of a tumour are radioresistant. During a fractionated course, which process makes them more sensitive to later fractions?

ARedistributionBSublethal damage repairCReoxygenationDRepopulation

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

The answer and the reasoning

C. Reoxygenation

As well-oxygenated cells are killed, the tumour shrinks and surviving hypoxic cells move closer to blood vessels and receive more oxygen. This reoxygenation is one of the four Rs of radiobiology and favours fractionation.

Option by option

A. Redistribution
Redistribution moves surviving cells into more sensitive phases of the cell cycle and does not address hypoxia.
B. Sublethal damage repair
Repair of sublethal damage mainly protects normal tissues between fractions and is not what sensitises hypoxic cells.
C. Reoxygenation (correct)
Correct. Hypoxic cells regain oxygen between fractions, becoming more radiosensitive.
D. Repopulation
Repopulation is regrowth of surviving cells, which reduces the effect of treatment.

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, Reoxygenation. As well-oxygenated cells are killed, the tumour shrinks and surviving hypoxic cells move closer to blood vessels and receive more oxygen.

Why is "Redistribution" not the answer?

Redistribution moves surviving cells into more sensitive phases of the cell cycle and does not address hypoxia.

Why is "Sublethal damage repair" not the answer?

Repair of sublethal damage mainly protects normal tissues between fractions and is not what sensitises hypoxic cells.

Why is "Repopulation" not the answer?

Repopulation is regrowth of surviving cells, which reduces the effect of treatment.

What concept does this question test?

It tests Radiotherapy and nuclear medicine basics: reoxygenation in Radiology. This reoxygenation is one of the four Rs of radiobiology and favours fractionation.

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 Radiotherapy and nuclear medicine basics: reoxygenation?

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.