ELEVATION PERFORMANCE OF 1.25D AND 1.5D TRANSDUCER ARRAYS

Present 1D phased array probes have outstanding lateral and axial reso lution, but their elevation performance is determined by a fixed apert ure focused at a fixed range. Multi-row array transducers can provide significantly improved elevation performance in return for ''modest'' increases in probe and system complexity. Time-domain simulations of e levation beam profiles are used to compare several types of multi-row probes. The elevation aperture of a 1.25D probe increases with range, but the elevation focusing of that aperture is static and determined p rincipally by a mechanical lens with a fixed focus (or foci). 1.25D pr obes can provide substantially better near-and far-field slice thickne ss performance than 1D probes and require no additional system beamfor mer channels. 1.5D probes use additional beamformer channels to provid e dynamic focusing and apodization in elevation. 1.5D probes can provi de detail resolution comparable to, and contrast resolution substantia lly better than, 1.25D probes, particularly in the mid-and far-field. Further increases in system channel count allow the use of 1.75D and 2 D arrays for adaptive acoustics and two-dimensional beam steering. Sig nificant improvements in clinical image quality can be expected as mul ti-row probes become increasingly available in the marketplace.