Radiotherapy: craniospinal irradiation: 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: craniospinal irradiation

Sample item

A child after resection of a posterior fossa medulloblastoma is to receive postoperative radiotherapy. Why is the whole neuraxis included in the fields?

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

The answer and the reasoning

D. The tumour spreads through CSF and can seed the spinal canal

Medulloblastoma tends to disseminate along the CSF pathways, producing drop metastases in the spine. Craniospinal irradiation treats the entire subarachnoid space, with a boost to the posterior fossa. Late effects in survivors, such as growth and cognitive problems, are significant.

Option by option

  • A. The cord is radioresistant

    The cord is not particularly radioresistant.

  • B. The brainstem requires prophylactic irradiation

    The brainstem is not treated prophylactically for this reason.

  • C. Medulloblastoma metastasises to bone only

    Bone is not the usual metastatic site.

  • D. The tumour spreads through CSF and can seed the spinal canal (correct)

    Correct. CSF seeding explains neuraxis 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.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, The tumour spreads through CSF and can seed the spinal canal. Medulloblastoma tends to disseminate along the CSF pathways, producing drop metastases in the spine.

Why is "The cord is radioresistant" not the answer?

The cord is not particularly radioresistant.

Why is "The brainstem requires prophylactic irradiation" not the answer?

The brainstem is not treated prophylactically for this reason.

Why is "Medulloblastoma metastasises to bone only" not the answer?

Bone is not the usual metastatic site.

What concept does this question test?

It tests Radiotherapy: craniospinal irradiation in Radiology. Craniospinal irradiation treats the entire subarachnoid space, with a boost to the posterior fossa. Late effects in survivors, such as growth and cognitive problems, are significant.

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: craniospinal irradiation?

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.