ARRT Image Acquisition and Evaluation 3

Question 1

A grid with a ratio of 16:1 is most appropriate for which clinical scenario?

Accepted Answer

Large body part requiring high kVp technique

Answer

High-ratio grids (12:1 or 16:1) are used for large anatomical areas where significant scatter is produced, especially at higher kVp settings.

Question 2

Quantum mottle (noise) in digital radiography is primarily caused by which factor?

Accepted Answer

Too few X-ray photons reaching the detector

Answer

Quantum mottle results from insufficient photon flux reaching the detector, producing a grainy, noisy appearance on the image.

Question 3

Which positioning error causes grid cutoff on a cross-table lateral projection?

Accepted Answer

Angling the tube across the grid lines

Answer

Angling the tube perpendicular to the grid lines (off-axis in the wrong direction) causes photons to be absorbed, resulting in grid cutoff.

Question 4

On a PA chest radiograph evaluated for proper exposure, which anatomical landmark is used to verify adequate penetration?

Accepted Answer

Faint visibility of the thoracic spine through the cardiac shadow

Answer

Adequate penetration on a PA chest is confirmed when the thoracic vertebrae are faintly visible through the cardiac silhouette.

Question 5

A radiograph exhibits a wide latitude (long scale) of contrast. Which exposure factor most directly caused this?

Accepted Answer

High kVp

Answer

Higher kVp produces more penetrating, homogenous radiation that results in low contrast (long gray scale) across the image.

ARRT - American Registry of Radiologic Technologists Practice Test