Non-Invasive Thermometry Using a Chirp Pulse Microwave---- Tomographic Measurement of Temperature Change in Saline Solution Phantoms of the Human Body

The paper is concerned with the non-invasive thermometry system of the human body using the chirp pulse microwave between 1 and 2 GHz. By spectral analysis of the beat signal between the incident and transmitted waves, only the signal transmitted on the straight line between the transmitting and receiving antennas is discriminated from multipath signals. The microwave tomogram can therefore be reconstructed easily using the conventional algorithms for an X-ray CT image. The microwave CT employs the chirp signal to remove the effect of multipath signals caused by diffraction and reflection, thereby permitting the imaging of dielectric materials with complicated structures, such as a human body. The experimental results show that the spatial resolution of the developed microwave CT is approximately 10 mm and that it is possible to measure the distribution of a temperature change of 0.7°C.