Thermoacoustic imaging is a hybrid technique combining electromagnetic and ultrasound waves to improve resolution and contrast. Short pulses of microwaves are used to excite ultrasound waves which are subsequnetly processed for image reconstruction. Using a new experimental setup we demonstrate results using ∼1 μμsec pulses with less than 5 kW peak power, significantly less than in previous works. Experimental results show agreement with numerical finite element modeling. Simulations suggests targets with conductivity in the range of 0.01 - 0.1 S/m and relative dielectric constants of ….

Microwave-Induced Thermoacoustic Imaging (TAI) is a noninvasive hybrid modality which improves contrast by using thermoelastic wave generation induced by microwave absorption. Ultrasonography is widely used in medical practice as a low-cost alternative and supplement to magnetic resonance imaging (MRI). Although ultrasonography has relatively high image resolution (depending on the ultrasonic wavelength at diagnostic frequencies), it suffers from low image contrast of soft tissues. In this work samples are irradiated with sub-microsecond electromagnetic pulses inducing acoustic waves in the sample that are then detected with an unfocused transducer. The advantage of this hybrid modality is the ability to take advantage of the microwave absorption coefficients which provide high contrast in tissue samples. This in combination with the superior spatial resolution of ultrasound waves is important to providing a low-cost alternative to MRI and early breast cancer detection methods. This work describes the implementation of a thermoacoustic experiment using a 5 kW peak power microwave source.