Imaging physics: filtration: 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 · Imaging physics: filtration

Sample item

Why is an aluminium filter added to the beam of a diagnostic X-ray tube?

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

The answer and the reasoning

A. To remove low-energy photons that add dose but not to the image

Low-energy photons are absorbed in the superficial tissues and never reach the film, so they add only skin dose. Filtration hardens the beam and reduces patient dose. Inherent plus added filtration is typically 2.5 mm aluminium equivalent.

Option by option

  • A. To remove low-energy photons that add dose but not to the image (correct)

    Correct. Filtration removes soft photons and lowers skin dose.

  • B. To increase the heat produced at the anode

    Filtration does not increase anode heating.

  • C. To increase the maximum photon energy

    The maximum energy is set by kVp, not by a filter.

  • D. To increase the field size

    Field size is controlled by the collimator.

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, To remove low-energy photons that add dose but not to the image. Low-energy photons are absorbed in the superficial tissues and never reach the film, so they add only skin dose.

Why is "To increase the heat produced at the anode" not the answer?

Filtration does not increase anode heating.

Why is "To increase the maximum photon energy" not the answer?

The maximum energy is set by kVp, not by a filter.

Why is "To increase the field size" not the answer?

Field size is controlled by the collimator.

What concept does this question test?

It tests Imaging physics: filtration in Radiology. Filtration hardens the beam and reduces patient dose. Inherent plus added filtration is typically 2.5 mm aluminium equivalent.

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 Imaging physics: filtration?

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.