Screen-film mammography typically provides around how many lp/mm of spatial resolution?

• A. 8 lp/mm
• B. 15 lp/mm
• C. 20 lp/mm
• D. 22 lp/mm

Answer: (B)

Spatial resolution measures how finely an imaging system can distinguish small details, and in mammography it’s expressed as line pairs per millimeter. In traditional screen-film mammography, the combination of the film grain and the intensifying screen, along with the processing and viewing geometry, provides a practical resolution of about 15 line pairs per millimeter. That level corresponds to details roughly on the order of a few tens of microns, enough to visualize most microcalcifications and subtle masses while still balancing noise and dose. Choices that imply much coarser detail (around 8 lp/mm) would blur small calcifications, whereas values around 20–22 lp/mm exceed what a typical screen-film system reliably achieves. Therefore, around 15 lp/mm is the best match for conventional screen-film mammography.