Microwave-induced thermo-acoustic (MITA) Tomography is a promising technique in medical imaging area. It is a combination of the microwave and ultrasound techniques. In this paper

an experimental system of MITA is briefly presented. The mechanism of MITA and some signal processing methods are applied in analyzing the characteristics and affects of the MITA signals. The affects

the irradiated microwave pulse and the geometry of the tissue are studied. Experiment results and theoretic analysis show that the amplitude of the time domain MITA signals are proportional to the intensity of the irradiated microwave pulse and the cross-section of the sample. The spectrum distribution of the MITA signals are not only affected by the spectrum of the irradiated microwave

but also affected by the intrinsic frequency determined by the tissue’s thickness. The center frequency of the MITA signals recorded in experiment accord with this hypothesis.