5MHz realtime sonography of the breast. 1. Technical equipment studies

: The resolving characteristics (depth dependence of spatial resolution) of different scanning units are tested by a specially designed tissue-mimicking phantom. The phantom includes cyst-like structures (0.8-5 mm) in several layers. Additional measurements of the lateral resolution (-6 dB beam width) are performed on a spherical test object. The results are compared with regard to the requested imaging depth (visualization of the breast muscle) and the optimum focus zone (depth of pathologic breast lesions) in 307 echomammographic examinations. It is shown that the resolution characteristics and penetration depth of a 5 MHz linear-array-real-time-scanner (LS 3000, Picker Inc.) with special near-range-focus best meet the requirements of breast echography.