ARRT Digital Imaging and Exposure Factors

Question 1

In digital radiography, which exposure indicator value signifies optimal exposure on most current CR/DR systems?

Accepted Answer

EI of 300 (system-dependent target near 300)

Answer

Most systems target an Exposure Index around 300 (±30%), though exact targets are vendor-specific and defined by the manufacturer.

Question 2

What does a deviation index (DI) of 0 indicate in a digital imaging system?

Accepted Answer

Exposure is exactly at the target exposure index

Answer

A deviation index of 0 means the actual exposure exactly matched the target exposure index, indicating optimal exposure.

Question 3

Which primary exposure factor has the greatest effect on subject contrast in digital radiography?

Accepted Answer

kVp (kilovoltage peak)

Answer

kVp controls the energy and penetrating power of the X-ray beam, directly determining the differential absorption that creates subject contrast.

Question 4

In computed radiography (CR), what component captures the latent image?

Accepted Answer

Photostimulable phosphor (PSP) imaging plate

Answer

CR uses a photostimulable phosphor imaging plate that stores a latent image as trapped electrons until scanned by a laser reader.

Question 5

What is the primary advantage of direct conversion flat-panel detectors (FPD) over indirect conversion FPDs?

Accepted Answer

Superior spatial resolution due to no light-spreading step

Answer

Direct conversion detectors convert X-rays directly to electrical signals without an intermediate light step, eliminating blur from light spread and improving spatial resolution.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Digital Imaging and Exposure Factors