Ultrasonic imaging by attenuation and pseudo-random signal

Extensive work has been done on medical ultrasonic tomography. However, the conventional pulse-echo technique suffers from various drawbacks; such as inability of obtaining image through tissue attenuation as those from the CAT scanner and limited resolution. The reflected ultrasound signal from a target by the conventional pulse-echo technique is determined by the reflection coefficient at the interface as well as the attenuation of the substance along the path. It is, therefore, impossible to retrieve these two types of information separately by the knowledge of a single reflected signal. Sophisticated techniques have been used to estimate the attenuation property by making assumptions that the reflection coefficient is independent of frequency. The resolution is inherently limited by the pulse width of the transmitting pulse. The work reported here focuses on the improvement of the above drawbacks