Radiation safety and radiobiology: law of Bergonie and Tribondeau: 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: law of Bergonie and Tribondeau

Sample item

A radiation oncologist observes that a poorly differentiated, rapidly proliferating tumour shrinks faster during treatment than a well-differentiated, slowly growing one. Which principle best explains this?

AWell-differentiated cells repair radiation damage faster than undifferentiated onesBCells that divide rapidly and are undifferentiated are the most radiosensitiveCRadiosensitivity depends only on the size of the nucleusDSlowly growing cells have a higher oxygen enhancement ratio

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

The answer and the reasoning

B. Cells that divide rapidly and are undifferentiated are the most radiosensitive

The law of Bergonie and Tribondeau links radiosensitivity to high mitotic activity, a long dividing future and little differentiation. Such cells reach the sensitive mitotic phases more often. Mature, slowly dividing cells are more resistant.

Option by option

A. Well-differentiated cells repair radiation damage faster than undifferentiated ones
Repair capacity is not what separates the two tumours in this stem.
B. Cells that divide rapidly and are undifferentiated are the most radiosensitive (correct)
Correct. Proliferative, undifferentiated cells are more sensitive.
C. Radiosensitivity depends only on the size of the nucleus
Nuclear size alone does not determine radiosensitivity.
D. Slowly growing cells have a higher oxygen enhancement ratio
The oxygen enhancement ratio is unrelated to growth rate in this way.

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 B, Cells that divide rapidly and are undifferentiated are the most radiosensitive. The law of Bergonie and Tribondeau links radiosensitivity to high mitotic activity, a long dividing future and little differentiation.

Why is "Well-differentiated cells repair radiation damage faster than undiffe…" not the answer?

Repair capacity is not what separates the two tumours in this stem.

Why is "Radiosensitivity depends only on the size of the nucleus" not the answer?

Nuclear size alone does not determine radiosensitivity.

Why is "Slowly growing cells have a higher oxygen enhancement ratio" not the answer?

The oxygen enhancement ratio is unrelated to growth rate in this way.

What concept does this question test?

It tests Radiation safety and radiobiology: law of Bergonie and Tribondeau in Radiology. Such cells reach the sensitive mitotic phases more often. Mature, slowly dividing cells are more resistant.

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: law of Bergonie and Tribondeau?

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.