Which statement best defines spatial resolution?

• A. The color depth of an image
• B. The grayscale range
• C. The ability to distinguish closely spaced structures
• D. The amount of noise in an image

Answer: (C)

Spatial resolution is about how finely an image samples space—how well the system can distinguish two objects that are very close to each other. In mammography, this means the ability to see two nearby structures as separate details rather than blending them into one blurry feature. The closer two structures are, the higher the spatial resolution needed to separate them; when resolution is high, small features like tiny calcifications or fine borders become discernible, which improves detection and characterization.

Factors that influence this capability include the detector’s pixel size, the focal spot size and geometry, and how the system blurs edges (the modulation transfer function). If the focal spot is large or the detector pixels are coarse, images blur more and closely spaced structures may merge, reducing spatial resolution.

Color depth and grayscale range describe color information and the number of grayscale levels, not the ability to resolve tiny details. Noise affects image quality and the visibility of details but is a separate issue from resolution itself.