Free RDA Radiographic Techniques and Errors Questions and Answers

Question 1

The radiographic error known as 'elongation,' where teeth appear stretched out, is caused by:

Accepted Answer

Insufficient vertical angulation

Answer

Elongation occurs when the vertical angulation of the x-ray beam is too flat or insufficient. This causes the beam to strike the tooth and film at a shallow angle, projecting a longer, distorted image onto the film.

Question 2

Overlapping of the interproximal contacts on a bitewing radiograph is a common error caused by:

Accepted Answer

Incorrect horizontal angulation

Answer

To open the contacts between teeth on a radiograph, the central x-ray beam must be directed parallel to the interproximal spaces. Incorrect horizontal angulation causes the beam to pass through the contacts at an angle, superimposing one tooth over the other.

Question 3

A 'cone cut' error on a radiograph appears as a clear, unexposed crescent or straight line and is caused by:

Accepted Answer

The PID not being centered over the film

Answer

A cone cut occurs when the primary x-ray beam is not aimed at the center of the film or sensor. As a result, part of the film is not exposed to radiation, leaving a clear, unexposed area that corresponds to the shape of the PID (Position Indicating Device) opening.

Question 4

In the paralleling technique, the central ray of the x-ray beam is directed:

Accepted Answer

Perpendicular to the film and the long axis of the tooth

Answer

The paralleling technique is based on the geometric principle of creating an accurate image by having the film parallel to the tooth's long axis. To avoid distortion, the central ray must then be directed perpendicular (at a 90-degree angle) to both the tooth and the film.

Question 5

The radiographic error that results in images appearing shorter and more stout than their actual size is called foreshortening. What is the cause?

Accepted Answer

Excessive vertical angulation

Answer

Foreshortening is the opposite of elongation and is caused by excessive or too-steep vertical angulation. This steep angle causes the image of the tooth to be projected onto a smaller area of the film, making it appear compressed or shorter.

(RDA) Registered Dental Assistant Practice Test

(RDA) Registered Dental Assistant Practice Test

Free RDA Radiographic Techniques and Errors Questions and Answers