Image Acquisition and Evaluation Flashcards

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

Answer: Large body part requiring high kVp technique

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

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

Answer: Too few X-ray photons reaching the detector

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

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

Answer: Angling the tube across the grid lines

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

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

Answer: Faint visibility of the thoracic spine through the cardiac shadow

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

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

Answer: High kVp

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

Which CR/DR artifact appears as a bright or dark line running across the image parallel to the scan direction?

Answer: Dropout line artifact

A dropout line artifact occurs when a row or column of detector elements fails, creating a bright or dark line across the image.

Which action best reduces magnification of a structure on a radiograph?

Answer: Decrease OID

Decreasing OID (object-to-image distance) brings the object closer to the receptor, reducing magnification.