ARRT Equipment Operation and QA 4

Question 1

What is the significance of the half-value layer (HVL) in x-ray quality control?

Accepted Answer

It indicates the penetrating ability of the x-ray beam and is used to assess beam quality and filtration adequacy

Answer

HVL is the thickness of a specified material that reduces beam intensity by 50%; it reflects beam energy (quality) and confirms adequate filtration is in place.

Question 2

Which artifact in digital radiography appears as a bright or dark line and is caused by a row or column of malfunctioning detector elements?

Accepted Answer

Dead pixel line artifact

Answer

A row or column of dead or malfunctioning detector elements produces a straight bright or dark line across the image in that direction.

Question 3

The Bucky factor (grid factor) is used to:

Accepted Answer

Determine how much exposure must be increased when using a grid compared to non-grid technique

Answer

The Bucky factor represents the ratio of exposure needed with a grid versus without; it accounts for the primary radiation absorbed by the grid and guides technique adjustment.

Question 4

In a three-phase, twelve-pulse generator, voltage ripple is approximately:

Accepted Answer

3-4%

Answer

Three-phase 12-pulse generators have a voltage ripple of approximately 3-4%, producing a nearly constant potential and a more efficient, higher average energy x-ray beam.

Question 5

Which of the following correctly describes the relationship between focal spot size and spatial resolution?

Accepted Answer

A smaller focal spot produces better spatial resolution by reducing geometric unsharpness

Answer

A smaller focal spot reduces geometric unsharpness (penumbra), which improves the sharpness and spatial resolution of the radiographic image.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Equipment Operation and QA 4