FREE EFDA Radiology & Dental Imaging Techniques Questions and Answers

Question 1

What is the primary purpose of the paralleling technique in dental radiography?

Accepted Answer

To achieve minimal image distortion and accurate tooth length

Answer

The paralleling technique, also known as the long-cone technique, positions the film or sensor parallel to the long axis of the tooth and the central ray perpendicular to both. This geometric relationship minimizes magnification and distortion, producing a radiograph that accurately represents the true length and shape of the tooth and surrounding structures. This accuracy is crucial for precise diagnosis and treatment planning.

Question 2

Which anatomical structure appears radiopaque on dental X-rays?

Accepted Answer

Enamel

Answer

Radiopaque structures appear white or light gray on dental X-rays because they absorb a significant amount of X-ray radiation. Enamel, being the most highly mineralized tissue in the body, is very dense and absorbs a large amount of radiation, making it appear distinctly radiopaque. Less dense structures like the pulp chamber or soft tissues appear radiolucent (darker).

Question 3

What is the recommended PID (Position-Indicating Device) length to reduce radiation scatter?

Accepted Answer

8 inches

Answer

A longer PID (Position-Indicating Device), typically 8 or 16 inches, helps reduce radiation scatter and magnification. While 16 inches is often preferred for minimal distortion, an 8-inch PID is a common and effective length for reducing scatter compared to shorter PIDs. The longer the PID, the more parallel the X-ray beams become, leading to a sharper image and less divergence of the beam.

Question 4

Which error occurs when the X-ray beam is not centered over the film/sensor?

Accepted Answer

Cone-cut

Answer

A cone-cut error occurs when the central X-ray beam is not properly aligned with the center of the film or sensor. This results in a clear, unexposed (white or black, depending on film/digital) crescent-shaped area on the radiograph where the X-ray beam did not reach the entire image receptor. It indicates improper angulation or positioning of the PID relative to the image receptor.

Question 5

What is the ALARA principle in dental radiography?

Accepted Answer

As Low As Reasonably Achievable

Answer

ALARA is a fundamental principle in radiation protection, standing for 'As Low As Reasonably Achievable.' In dental radiography, this means using the lowest possible dose to achieve diagnostic quality images, employing techniques like lead aprons, thyroid collars, fast films/digital sensors, and proper exposure settings to minimize patient and operator exposure to radiation.

EFDA - Expanded Function Dental Assistant Certification Practice Test

EFDA - Expanded Function Dental Assistant Certification Practice Test

FREE EFDA Radiology & Dental Imaging Techniques Questions and Answers