Radiation safety and radiobiology: fluoroscopy geometry: 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: fluoroscopy geometry

Sample item

An interventional radiologist performs a long fluoroscopic procedure on a C-arm. Which arrangement gives the lowest scatter dose to the operator's upper body?

AX-ray tube beneath the table with the receptor above the patientBX-ray tube above the table with the receptor belowCMaximum magnification with the receptor far from the patientDLateral projection with the tube on the operator's side

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

The answer and the reasoning

A. X-ray tube beneath the table with the receptor above the patient

Scatter is greatest on the entrance side of the patient. With the tube under the table, the highest scatter is toward the lower body, where the table and apron give protection, so the head and chest receive less. Lateral projection from the operator's side and magnification raise dose.

Option by option

A. X-ray tube beneath the table with the receptor above the patient (correct)
Correct. An under-couch tube keeps the strongest scatter low and away from the operator's head and chest.
B. X-ray tube above the table with the receptor below
An over-couch tube sends the strongest scatter up toward the operator.
C. Maximum magnification with the receptor far from the patient
Magnification needs a higher dose rate and increases scatter.
D. Lateral projection with the tube on the operator's side
A tube on the operator's side puts the entrance-side scatter directly on the operator.

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 A, X-ray tube beneath the table with the receptor above the patient. Scatter is greatest on the entrance side of the patient.

Why is "X-ray tube above the table with the receptor below" not the answer?

An over-couch tube sends the strongest scatter up toward the operator.

Why is "Maximum magnification with the receptor far from the patient" not the answer?

Magnification needs a higher dose rate and increases scatter.

Why is "Lateral projection with the tube on the operator's side" not the answer?

A tube on the operator's side puts the entrance-side scatter directly on the operator.

What concept does this question test?

It tests Radiation safety and radiobiology: fluoroscopy geometry in Radiology. With the tube under the table, the highest scatter is toward the lower body, where the table and apron give protection, so the head and chest receive less. Lateral projection from the operator's side and magnification raise dose.

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: fluoroscopy geometry?

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.