A MAGNIFICATION MAMMOGRAPHY TECHNIQUE USI NG STORAGE PHOSPHOR PLATES - EXPERIMENTAL INVESTIGATIONS CONCERNING SPATIAL-RESOLUTION AND DETECTION OF MICROCALCIFICATIONS

Purpose: Since the routine use of storage phosphor systems for mammogr aphy has been limited by its inadequate spatial resolution of 5 linepa irs/mm, a combination of a magnification mammography technique with st orage 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 b reast with 1.7x magnification (m), and spot views with 4x magnificatio n. The digital image receptor comprised a high resolution storage phos phor plate. To determine spatial resolution, contrast transfer curves were obtained, and the detection of microcalcifications was investigat ed by ROC (receiver operating characteristic) analysis. Results: Spati al 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 techniqu e compared to the conventional screen-film mammography technique, Conc lusions: The limitations of digital mammography with respect to spatia l resolution can be overcome by using a high magnification technique.