Numerical study of microwave-induced thermoacoustic effect for early breast cancer detection

In this paper, the relation of the induced acoustic waves to the width, carrier frequency and polarization of irradiation pulse is studied based on FDTD numerical simulation. Thermoacoustic signals of a single tumor induced by microwave pulses with different characteristics were obtained and the excited acoustic signals of two breast cancers observed at different positions were also described. It is shown that: (1) the induced thermoacoustic signal does not have the changeless relation to the carrier frequency of the irradiation pulse; (2) the width of the induced thermoacoustic signal is directly determined by the width of the microwave pulse and the amplitude of the acoustic signal is inversely proportional to the microwave pulse width; (3) the excited acoustic wave of geometrical non-symmetry breast cancer varies with the polarization of the irradiation pulse; (4) the thermoacoustic signals of two closely located breast cancers observed at different positions are different, and the two tumors can be distinguished clearly from the observed signal when the observed position is suitably chosen.