PHANTOMS AND AUTOMATED-SYSTEM FOR TESTING THE RESOLUTION OF ULTRASOUND SCANNERS

Tissue-mimicking phantoms and an automated system have been developed for testing the resolution performance of ultrasound scanners by deter mining detectability of low to higher contrast spherical lesions over the entire depth of field. Axial, lateral and elevational resolutions are accounted for simultaneously and equally. Tissue-mimicking spheric al simulated lesions are either 3 or 4 mm in diameter and have one of four different intrinsic material contrasts. For each diameter and con trast, there is a set of 109 lesions in a regular array with coplanar centers extending from 0.5-15.5 cm in depth. With the scan slice super imposed on the spheres, the image is frame-grabbed for automated analy sis. A diameter-dependent lesion signal-to-noise ratio is computed for each pixel position in the image, excluding a 5-mm boundary. Two univ ersal thresholds, resulting from maximization of agreement between the automated system and human observers, give rise to a depth range, or ''resolution zone'', over which detection exists for each type lesion. (C) 1997 World Federation for Ultrasound in Medicine & Biology.