In screen-film mammography, the practical limit for resolving fine details is commonly cited as approximately

• A. 10 lp/mm
• B. 15 lp/mm
• C. 18 lp/mm
• D. 30 lp/mm

Answer: (B)

Spatial resolution describes how finely a imaging system can distinguish adjacent details. In screen-film mammography, the high-frequency performance is limited by the screen phosphor grain, film grain, and geometric unsharpness from the focal spot and geometry. These factors together cap the practical resolving power of a typical screen-film system at about 15 line pairs per millimeter. At this limit, the smallest detail you can reliably separate is roughly 1/30 mm (about 33 microns), which aligns with the level needed to detect clinically relevant features like microcalcifications while keeping image contrast and noise in balance. Higher values such as 18 or 30 lp/mm would exceed what standard screen-film systems can consistently deliver, and 10 lp/mm would underrepresent what is routinely achievable.