William Tobocman

Emeritus Professor of Physics

Analysis of wave field scattering is the primary method we have for learning about the world about us. Our eyes detect scattered light and our ears detect scattered sound. These signals are then processed by our brain to provide us with information about the outside world. This is called remote sensing. By means of scattering theory this process may be extended to include wave fields which are beyond the range of sensitivity of our eyes and ears; for example, x-rays, radio waves, ultrasound, electron beams, etc. In scattering theory there are two classes of problems: direct scattering and inverse scattering. In the direct scattering problem the task is to calculate the scattered wave field given a knowledge of the incident wave field and the target. The inverse scattering problem, on the other hand, sets the task of determining the properties of the target from knowledge of the incident and scattered wave fields. In recent years I have worked on the direct and inverse scattering problems for acoustic waves. The particular object of this research has been the refinement of ultrasound medical imaging. We have developed a technique for processing the reflected ultrasound so that one recovers a more detailed (better resolved) image of tissue structures within the body. To test the concept we have been collecting ultrasound data in our laboratory from autopsied human tissue specimens. The data is processed with inverse scattering computer programs developed for the purpose. We have gotten good results with artery specimens where we could provide detailed information concerning the nature and extent of atherosclerotic disease in the artery wall. We are currently working with prostate specimens to see if we can make ultrasound a better tool for detecting prostate cancer.