Radiation safety and radiobiology: shielding a pure beta emitter: 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: shielding a pure beta emitter

Sample item

A technologist handles a vial of the pure beta emitter Y-90 and is told to use acrylic shielding first rather than lead. Why?

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

The answer and the reasoning

C. Lead produces penetrating bremsstrahlung X-rays from beta particles

Fast electrons decelerating in a high atomic number material produce bremsstrahlung X-rays. A low-Z material such as acrylic stops betas with little bremsstrahlung, and a thin lead layer outside it can then stop what is produced.

Option by option

  • A. Lead becomes radioactive when struck by betas

    Lead does not become radioactive from beta bombardment.

  • B. Acrylic reflects beta particles back to the vial

    Reflection of betas is not the reason for choosing acrylic.

  • C. Lead produces penetrating bremsstrahlung X-rays from beta particles (correct)

    Correct. High-Z shielding generates secondary X-rays when it stops betas.

  • D. Acrylic absorbs gamma rays better than lead

    Acrylic is a poor absorber of gamma rays compared with lead.

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 C, Lead produces penetrating bremsstrahlung X-rays from beta particles. Fast electrons decelerating in a high atomic number material produce bremsstrahlung X-rays.

Why is "Lead becomes radioactive when struck by betas" not the answer?

Lead does not become radioactive from beta bombardment.

Why is "Acrylic reflects beta particles back to the vial" not the answer?

Reflection of betas is not the reason for choosing acrylic.

Why is "Acrylic absorbs gamma rays better than lead" not the answer?

Acrylic is a poor absorber of gamma rays compared with lead.

What concept does this question test?

It tests Radiation safety and radiobiology: shielding a pure beta emitter in Radiology. A low-Z material such as acrylic stops betas with little bremsstrahlung, and a thin lead layer outside it can then stop what is produced.

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: shielding a pure beta emitter?

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.