Abstract
In clinical diagnosis, ultrasound is superior to X-ray in respects of safety and ability to image characteristic of soft tissues. A pulse-echo ultrasonic imaging is now widely applied to the clinical use. Unfortunately, however, the images are not quantitative and their resolution is not sufficient since the imaging uses reflected ultrasound signals on the assumption that the ultrasonic beam is very sharp and travels in straight lines. The assumption is not true in all biological tissues. Images of ultrasonic CT by using technique of X-ray CT also have artifacts because of the same reasons.
Diffraction tomography, which is CT considering wave diffraction effect, is expected to reconstruct quantitatively a higher resolution image. In clinical use, however, the range of insonifying angle is often limited. It is therefore an important problem how accurate image under this ill-posed condition can be reconstructed. In regard to this problem, we have proposed a new restoration method by using maximum entropy method and iterative revisions. Simulation results have shown that it is possible to restore the image under this ill-posed condition.
In this paper, we present the results of experimental investigation on this method. The results coincide with the same tendency as simulation results.
