Thermoacoustic Images Generated by a 2450 MHz Portable Source and Applicator

Abstract

Acoustic signals generated by deeply penetrating radiation in soft tissue offer the possibility of producing medical images unique in the sense that the imaging parameters differ from those in current use. The potential for such images is twofold: low level inducing fields such as rf or microwave could be used to generate diagnostic images, or the fields present in therapy could be used to generate information on energy deposition during tumor irradiation or offer thermometric assistance in hyperthermia. Earlier work presented in these symposia discussed the theory and presented confirming experimental results for various sources of radiation. These emissions were produced by low-level, pulsed microwave radiation. The present work represents a significant advance in two respects: resolution has been greatly improved with a highefficiency broadband transducer, and microwave radiation is coupled into an interrogated region of arbitrary size and shape using an applicator horn matched to water and fed from a 2450 MHz microwave source similar to that used in clinical hyperthermia.