Radiation safety and radiobiology: gastrointestinal syndrome mechanism: 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: gastrointestinal syndrome mechanism

Sample item

A person exposed to a very high whole-body dose has profuse bloody diarrhoea, dehydration and sepsis within the first two weeks and dies despite marrow support. What is the underlying lesion?

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

The answer and the reasoning

B. Loss of intestinal crypt stem cells with denudation of the mucosa

Intestinal crypt cells divide rapidly and are killed by high doses, so villi are not replaced and the mucosal barrier is lost. This gives fluid loss, bacterial translocation and sepsis, which marrow support cannot correct.

Option by option

  • A. Failure of bone marrow stem cells alone

    Marrow failure explains the haematopoietic syndrome and appears at lower doses with a later course.

  • B. Loss of intestinal crypt stem cells with denudation of the mucosa (correct)

    Correct. Without crypt cells the villous lining is lost and cannot regenerate.

  • C. Hepatic veno-occlusion

    Hepatic veno-occlusion is a complication of high-dose chemotherapy or hepatic radiation and is not the cause of diarrhoea.

  • D. Radiation vasculitis of cerebral vessels

    Cerebral vascular injury underlies the neurovascular syndrome with seizures and ataxia.

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.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is B, Loss of intestinal crypt stem cells with denudation of the mucosa. Intestinal crypt cells divide rapidly and are killed by high doses, so villi are not replaced and the mucosal barrier is lost.

Why is "Failure of bone marrow stem cells alone" not the answer?

Marrow failure explains the haematopoietic syndrome and appears at lower doses with a later course.

Why is "Hepatic veno-occlusion" not the answer?

Hepatic veno-occlusion is a complication of high-dose chemotherapy or hepatic radiation and is not the cause of diarrhoea.

Why is "Radiation vasculitis of cerebral vessels" not the answer?

Cerebral vascular injury underlies the neurovascular syndrome with seizures and ataxia.

What concept does this question test?

It tests Radiation safety and radiobiology: gastrointestinal syndrome mechanism in Radiology. This gives fluid loss, bacterial translocation and sepsis, which marrow support cannot correct.

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 Radiation safety and radiobiology: gastrointestinal syndrome mechanism?

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.