Radiation safety: background dose: 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: background dose

Sample item

The world average annual effective dose from natural background radiation is closest to which of the following?

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

The answer and the reasoning

B. About 2.4 mSv

Natural sources, chiefly radon, cosmic rays, terrestrial gamma radiation and ingested radionuclides, contribute about 2.4 mSv per year worldwide. Radon is the largest single contributor. A chest radiograph equals about a few days of background.

Option by option

  • A. About 240 mSv

    240 mSv is far too high.

  • B. About 2.4 mSv (correct)

    Correct. The global average is about 2.4 mSv per year.

  • C. About 24 mSv

    24 mSv is ten times too high.

  • D. About 0.024 mSv

    0.024 mSv is one hundred times too low.

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, About 2.4 mSv. Natural sources, chiefly radon, cosmic rays, terrestrial gamma radiation and ingested radionuclides, contribute about 2.

Why is "About 240 mSv" not the answer?

240 mSv is far too high.

Why is "About 24 mSv" not the answer?

24 mSv is ten times too high.

Why is "About 0.024 mSv" not the answer?

0.024 mSv is one hundred times too low.

What concept does this question test?

It tests Radiation safety: background dose in Radiology. 4 mSv per year worldwide. Radon is the largest single contributor. A chest radiograph equals about a few days of background.

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: background dose?

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.