Ex Vivo Thermoacoustic Imaging Over Large Fields of View With 108 MHz Irradiation

Thermoacoustic signals are generated over a large field of view by 900 ns TE₁₀ pulses with 108 MHz carrier frequency. Test specimens selectively absorb the TE₁₀ pulse energy producing rapid thermal expansions that generate ultrasonic pulses. 108 MHz irradiation provides excellent depth penetration in soft tissue, allowing blood and physiologic saline to generate strong signals. Thermoacoustic signal generation from a depth of several cm is well above our system´s noise floor. Rotating the test specimen provides single-slice tomographic signal encoding. Filtered back-projection reconstruction yields images over a 6.4 cm field of view. Reconstructions of tissue mimicking prostate phantoms and fresh porcine kidney tissue are presented.