Basic investigation on reflection mode ultrasonic attenuation tomography

Quantitative evaluation of tissue character by medical ultrasound is called \lq\lqtissue characterization”, and it is one of the most important themes for medical ultrasonics. \lq\lqUltrasonic computed tomography (CT)” is expected to enable reconstruction of a quantitative image, which can show new diagnostic information such as the slope of the attenuation coefficient. Transmission mode CT and diffraction tomography, however, are affected by bone and unknown ultrasonic characters. In this paper, a new method of reconstructing an exact and quantitative distribution of the slope of the attenuation coefficient is proposed. This method uses reflected pulse waves in order to avoid the influence of bone. Moreover, this method is independent of unknown sound velocities, transmittances, reflectances and white noise. Simulation results show that it is possible to reconstruct a quantitative image of a region including bone from noisy data, by this method.