Radiotherapy and nuclear medicine basics: samarium-153 therapy: 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 and nuclear medicine basics: samarium-153 therapy

Sample item

A patient with painful osteoblastic metastases from prostate cancer receives samarium-153 EDTMP for pain palliation. What is the dose-limiting toxicity?

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

The answer and the reasoning

A. Myelosuppression

Samarium-153 EDTMP is a beta-emitting bone-seeking agent that irradiates the adjacent marrow, so thrombocytopenia and leucopenia limit treatment. Blood counts should be monitored after each dose.

Option by option

  • A. Myelosuppression (correct)

    Correct. Marrow irradiation from bone-seeking beta emitters causes myelosuppression.

  • B. Cardiotoxicity

    Cardiotoxicity is not a recognised effect of bone-seeking beta emitters.

  • C. Pulmonary fibrosis

    Pulmonary fibrosis is not related to the biodistribution of this agent.

  • D. Nephrotoxicity

    The agent is excreted in urine but is not nephrotoxic at therapeutic doses.

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 A, Myelosuppression. Samarium-153 EDTMP is a beta-emitting bone-seeking agent that irradiates the adjacent marrow, so thrombocytopenia and leucopenia limit treatment.

Why is "Cardiotoxicity" not the answer?

Cardiotoxicity is not a recognised effect of bone-seeking beta emitters.

Why is "Pulmonary fibrosis" not the answer?

Pulmonary fibrosis is not related to the biodistribution of this agent.

Why is "Nephrotoxicity" not the answer?

The agent is excreted in urine but is not nephrotoxic at therapeutic doses.

What concept does this question test?

It tests Radiotherapy and nuclear medicine basics: samarium-153 therapy in Radiology. Blood counts should be monitored after each dose.

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: samarium-153 therapy?

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.