BASIC INVESTIGATION ON REFLECTION MODE ULTRASONIC-ATTENUATION TOMOGRAPHY

Quantitative evaluation of tissue character by medical ultrasound is c alled ''tissue characterization'', and it is one of the most important themes for medical ultrasonics. ''Ultrasonic computed tomography (CT) '' is expected to enable reconstruction of a quantitative image, which can show new diagnostic information such as the slope of the attenuat ion coefficient. Transmission mode CT and diffraction tomography, howe ver, are affected by bone and unknown ultrasonic characters. In this p aper, a new method of reconstructing an exact and quantitative distrib ution of the slope of the attenuation coefficient is proposed. This me thod uses reflected pulse waves in order to avoid the influence of bon e. Moreover, this method is independent of unknown sound velocities, t ransmittances, reflectances and white noise. Simulation results show t hat it is possible to reconstruct a quantitative image of a region inc luding bone from noisy data, by this method.