Radiation safety and radiobiology: radon: 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: radon

Sample item

Which source contributes the largest share of the average annual dose to the population from natural background radiation?

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

The answer and the reasoning

B. Radon and its decay products

Radon, a gas released from uranium-bearing rocks and soil, accumulates in buildings and is the largest component of natural background exposure when inhaled. It is also an important cause of lung cancer in non-smokers.

Option by option

  • A. Cosmic rays

    Cosmic rays contribute a smaller share which rises with altitude.

  • B. Radon and its decay products (correct)

    Correct. Inhaled radon progeny deliver the biggest portion of the natural dose.

  • C. Potassium-40 in body tissues

    Potassium-40 inside the body gives a small, fairly constant internal dose.

  • D. Terrestrial gamma rays

    Terrestrial gamma radiation is a smaller part of background.

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, Radon and its decay products. Radon, a gas released from uranium-bearing rocks and soil, accumulates in buildings and is the largest component of natural background exposure when inhaled.

Why is "Cosmic rays" not the answer?

Cosmic rays contribute a smaller share which rises with altitude.

Why is "Potassium-40 in body tissues" not the answer?

Potassium-40 inside the body gives a small, fairly constant internal dose.

Why is "Terrestrial gamma rays" not the answer?

Terrestrial gamma radiation is a smaller part of background.

What concept does this question test?

It tests Radiation safety and radiobiology: radon in Radiology. It is also an important cause of lung cancer in non-smokers.

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: radon?

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.