Measurement of temperature distribution in phantom body by an ultrasonic CT method

An ultrasonic CT method was researched for measuring indirectly the interio r temperature distribution from a series of sound speed projections, which were taken at several different orientations relative to a phantom body. Fi rst, we compared three popular reconstruction algorithms to minimize a requ ired number of projections. Then, phantom made of agar was placed in a wate r bath, and a series of sound speed projections was measured when a pair of ultrasonic detectors were both translated and rotated. We could obtain the temperature distribution in phantom by subtracting the sound speed before heating from the sound speed after heating. When bone or gas is in the area of measurement, projections include a data missing part. If the missing pa rt was small, we could obtain approximately the reconstructed image by modi fying the projections.