In ultrasound hyperthermia, focal patterns generated by phased arrays can be degraded by phase errors due to tissue inhomogeneities, digitization of the driving signals, and imperfect fabrication of the transducers. the degree of degradation depends on the severity of phase aberrations. As predicted by simulation and verified by experimental results, focal degradation scales. with, the circular variance of phase errors, However, degraded power deposition patterns can be significantly improved after phase aberration correction, especially where patterns are complicated and the aberrations are severe. Also, as shown in motion compensation experiments, an aberration corrected pattern can be particularly sensitive to aberrator movement greater than the correlation length of the aberrator. After motion compensation, new sharply focused patterns can be accomplished, thus reducing the unwanted influence of “body” movement by stabilizing the positions of foci with respect to patient anatomy.
|Original language||English (US)|
|Number of pages||10|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|State||Published - Jan 1994|
Bibliographical noteFunding Information:
Manuscript received December 30, 1992; revised and accepted August 9, 1993. This work was supported in part by the National Institutes of Health under Grant CA44124, by Hitachi Central Research Laboratory, Hitachi, Ltd., Tokyo, Japan, and by the National Center for Supercomputer Applications at the University of Illinois under Grant ECS87OOO1. The authors are with the Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109. IEEE Log Number 9213934.