CT: window settings: 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 · CT: window settings

Sample item

A radiologist wants to evaluate the lung parenchyma for emphysema on a CT chest. Which window setting is the most suitable?

ANarrow window with a level of 80 HUBBone window with a level of 300 HUCNarrow window with a level of about 40 HUDWide window with a low (negative) level

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

The answer and the reasoning

D. Wide window with a low (negative) level

Lung tissue is of very low density, so a wide window (about 1500 HU) centred near -600 HU is used. Mediastinal and soft tissue windows use a level near 40 HU and a width of 350 to 400. Narrow windows are used for subtle soft tissue contrast, such as brain.

Option by option

A. Narrow window with a level of 80 HU
A narrow level of 80 HU would suit subtle brain contrast.
B. Bone window with a level of 300 HU
A bone window suits skeletal detail, not air-containing lung.
C. Narrow window with a level of about 40 HU
A level of 40 HU with a narrow window suits soft tissue and mediastinum.
D. Wide window with a low (negative) level (correct)
Correct. Lung is viewed with a wide window centred on a negative level.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, Wide window with a low (negative) level. Lung tissue is of very low density, so a wide window (about 1500 HU) centred near -600 HU is used.

Why is "Narrow window with a level of 80 HU" not the answer?

A narrow level of 80 HU would suit subtle brain contrast.

Why is "Bone window with a level of 300 HU" not the answer?

A bone window suits skeletal detail, not air-containing lung.

Why is "Narrow window with a level of about 40 HU" not the answer?

A level of 40 HU with a narrow window suits soft tissue and mediastinum.

What concept does this question test?

It tests CT: window settings in Radiology. Mediastinal and soft tissue windows use a level near 40 HU and a width of 350 to 400. Narrow windows are used for subtle soft tissue contrast, such as brain.

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 CT: window settings?

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.