Which of the following QC parameters are tested annually?

• A. Screen/film contact only
• B. Grid alignment only
• C. Screen/film and cassette matching only
• D. Screen/film contact, grid alignment, and cassette matching

Answer: (D)

Annual QC checks the imaging chain across several interrelated parameters to ensure overall image quality and system reliability. The screen/film contact test verifies that the screens sit in tight, uniform contact with the film inside the cassette. Any gaps or bowing between screen and film can cause light to spread unevenly, blurring detail and reducing sharpness, especially in areas away from the center.

Grid alignment is examined to confirm the grid sits correctly with respect to the beam. If the grid is not properly aligned, grid cut-off appears as unwanted density patterns on the image, compromising uniformity and contrast, which is why precise centering and angle alignment are essential.

Cassette matching assesses the compatibility between the film and screen pair. When the film and screen are not properly matched, image speed and contrast can be off, leading to suboptimal exposure latitude and resolution. Ensuring appropriate cassette/film-screen pairing maintains intended image quality and diagnostic reliability.

These tests are typically performed annually as part of a comprehensive system evaluation, distinguishing them from daily or monthly checks that address other aspects like processing stability and basic reproducibility.