Which measure, in numbers, is used to express the spatial resolution of screen-film mammography?

• A. 5 lp/mm
• B. 15 lp/mm
• C. 50 lp/mm
• D. 100 lp/mm

Answer: (B)

Spatial resolution in screen-film mammography is quantified by line pairs per millimeter. This metric measures how finely an image can distinguish alternating dark and light lines; a higher number means the detector can resolve finer details. In mammography, capturing small structures such as microcalcifications requires a high resolving capability, and a typical high-resolution specification sits around 15 line pairs per millimeter. So the numerical expression used is 15 line pairs per millimeter.

Lower values, like 5 lp/mm, would understate the system’s ability to show fine details, while extremely high values such as 50 or 100 lp/mm exceed what standard screen-film technology can reliably deliver and aren’t representative of typical screen-film mammography performance.