Radiotherapy: electron beam for superficial tumours: 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 · Radiotherapy: electron beam for superficial tumours

Sample item

A 1.5 cm thick basal cell carcinoma on the cheek is to be irradiated with minimal dose to the underlying tissue. Which beam is most suitable?

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

The answer and the reasoning

A. An electron beam of suitable energy

Electrons deposit dose within a finite range and then fall off steeply, so deep tissues are spared. This suits skin and other superficial tumours, with the energy chosen to match the depth. Megavoltage photons penetrate deeply and are used for deeper lesions.

Option by option

  • A. An electron beam of suitable energy (correct)

    Correct. Electrons have a limited range with rapid dose fall-off.

  • B. A megavoltage photon beam with several fields

    Megavoltage photons would irradiate deeper tissue unnecessarily.

  • C. A gamma knife

    A gamma knife is for intracranial stereotactic work.

  • D. Whole-body irradiation

    Whole-body irradiation is not related to a localised skin lesion.

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, An electron beam of suitable energy. Electrons deposit dose within a finite range and then fall off steeply, so deep tissues are spared.

Why is "A megavoltage photon beam with several fields" not the answer?

Megavoltage photons would irradiate deeper tissue unnecessarily.

Why is "A gamma knife" not the answer?

A gamma knife is for intracranial stereotactic work.

Why is "Whole-body irradiation" not the answer?

Whole-body irradiation is not related to a localised skin lesion.

What concept does this question test?

It tests Radiotherapy: electron beam for superficial tumours in Radiology. This suits skin and other superficial tumours, with the energy chosen to match the depth. Megavoltage photons penetrate deeply and are used for deeper lesions.

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 Radiotherapy: electron beam for superficial tumours?

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.