Image Quality and Interpretation Flashcards

Which artifact appears as a grid-like pattern overlaid on the radiographic image when the grid is not properly aligned with the X-ray beam?

Answer: Moiré pattern

A moiré pattern results from misalignment between the grid lines and the scanning frequency, producing an interference pattern on the image.

A radiograph shows areas of increased density at the periphery of the image with decreased density at the center. What is the most likely cause?

Answer: Anode heel effect

The anode heel effect causes decreased intensity on the anode side and increased intensity on the cathode side, creating uneven density across the image.

Which factor primarily determines the recorded detail (sharpness) in a radiographic image?

Answer: Focal spot size

A smaller focal spot size reduces geometric unsharpness (penumbra), resulting in sharper recorded detail.

When evaluating a chest radiograph, you notice the left hemidiaphragm appears elevated and the mediastinum is shifted to the left. What does this suggest?

Answer: Left lung collapse (atelectasis)

Atelectasis (collapse) causes the hemidiaphragm to elevate and shifts the mediastinum toward the affected side due to volume loss.

What is the primary purpose of using a high kVp technique in chest radiography?

Answer: To penetrate the mediastinum and show lung detail simultaneously

High kVp (120+ kVp) provides sufficient penetration of the dense mediastinum while still showing lung parenchyma, balancing contrast across different tissue densities.

Which term describes the ability of an imaging system to distinguish between two adjacent structures that have very similar subject contrast?

Answer: Contrast resolution

Contrast resolution (low-contrast detectability) is the ability to differentiate between structures with similar densities, distinct from spatial resolution which refers to sharpness.

A lateral lumbar spine radiograph shows the vertebral bodies but the spinous processes are not visible. What technique error is most likely responsible?

Answer: Insufficient penetration (too low kVp)

Low kVp results in insufficient penetration through the dense posterior elements, making the spinous processes invisible on the lateral projection.