An attempt of time domain microwave computed tomography for biomedical use

So-called time-domain measurement techniques were employed for visualizing the complex permittivity distribution inside a human body. A microwave pulse with a bandwidth from 0.8 GHz to 4.2 GHz is radiated from a transmitting antenna toward the object immersed in a saline solution that is called a bolus. The transmitted signal is detected by a receiving antenna that is placed on the opposite side of the transmitting antenna. The signal transmitted on the straight path between those two antennas is measured by leaving only the signal that corresponds to the transmission time between those two antennas. This procedure is repeated to obtain a complete set of projection data of the target while the antenna pair is moved on and around the translation- and rotation-axes just like the first generation X-ray CT. The transmission time between two antennas is estimated from complex permittivity of a bolus and biological phantoms. It was demonstrated that time-domain microwave computed tomography (TD-MCT) is feasible by measuring only the transmitted signal on a straight-transmission-path between two antennas by means of a time-domain measurement technique.