Dental materials and radiology basics: reversed film placement: practice question

A Dentistry 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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Dentistry · Dental materials and radiology basics: reversed film placement

Sample item

A periapical film appears pale with a fine criss-cross, herringbone pattern over the whole image. What error is most likely?

AThe beam was not centred and cut off one sideBThe film was placed back-to-frontCThe film was exposed twice by mistakeDThe developer solution was too cold

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

The answer and the reasoning

B. The film was placed back-to-front

The lead foil behind the film is embossed with a pattern. If the film is placed with its back towards the tube, the beam passes through the foil first and the pattern is cast onto the image, which is also lighter because of beam attenuation. Correct placement has the front of the packet, without the embossed foil, facing the tube.

Option by option

A. The beam was not centred and cut off one side
A beam not centred causes a sharp unexposed edge, not a pattern over the whole film.
B. The film was placed back-to-front (correct)
Correct. The embossed lead foil pattern is superimposed when the film faces the wrong way.
C. The film was exposed twice by mistake
A double exposure shows two overlapping images, not a herringbone pattern.
D. The developer solution was too cold
Cold developer gives a pale film but not a criss-cross pattern.

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 Dentistry question

What is the answer to this Dentistry question?

The best answer is B, The film was placed back-to-front. The lead foil behind the film is embossed with a pattern.

Why is "The beam was not centred and cut off one side" not the answer?

A beam not centred causes a sharp unexposed edge, not a pattern over the whole film.

Why is "The film was exposed twice by mistake" not the answer?

A double exposure shows two overlapping images, not a herringbone pattern.

Why is "The developer solution was too cold" not the answer?

Cold developer gives a pale film but not a criss-cross pattern.

What concept does this question test?

It tests Dental materials and radiology basics: reversed film placement in Dentistry. If the film is placed with its back towards the tube, the beam passes through the foil first and the pattern is cast onto the image, which is also lighter because of beam attenuation. Correct placement has the front of the packet, without the embossed foil, facing the tube.

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 Dental materials and radiology basics: reversed film placement?

Learn the dental formula, eruption ages and tooth structure once, as tables. Then use the flashcards and the other Dentistry 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.