A magnification mammography technique using storage phosphor plates: Experimental investigations concerning spatial resolution and detection of microcalcifications.

Purpose: Since the routine use of storage phosphor systems for mammography has been limited by its inadequate spatial resolution of 5 linepairs/mm, a combination of a magnification mammography technique with storage phosphor plates was investigated to detect microcalcifications. Material and Methods: A new mammography system with a microfocus tube using an anode of 0.05-0.12 mm allowed to obtain survey views of the breast with 1.7x magnification (m), and spot views with 4x magnification. The digital image receptor comprised a high resolution storage phosphor plate. To determine spatial resolution, contrast transfer curves were obtained, and the detection of microcalcifications was investigated by ROC (receiver operating characteristic) analysis. Results: Spatial resolution for digital survey views (m=1.7) was 8 linepairs/mm and for spot views (m=4) was 18 linepairs/mm. ROC analysis demonstrated a significantly higher performance of the digital magnification technique compared to the conventional screen-film mammography technique, Conclusions: The limitations of digital mammography with respect to spatial resolution can be overcome by using a high magnification technique.