Reflex Transmission Imaging

Abstract

Reflex transmission imaging (RTI) is a method for making orthographic acoustic transmission images without requiring the presence of an acoustic source on the opposite side of the object. It is well-suited to imaging specific planes in objects of moderate scatter cross section, such as human tissue. Each pixel of the image is formed by pulsing a transducer that is well-focused at the image plane, then rectifying and integrating the signals received from a selected range zone beyond the focus. This zone acts as a spatially and temporally incoherent insonification source. The pixel value is diminished twice by the attenuation at that focal point. A complete image is produced by raster scanning or bidirectional sector scanning; a reflection C-scan can be acquired simultaneously. Reflex transmission images can be made with a relatively small transducer. For medical diagnosis, RTI can be readily integrated with a real-time B-scanner, allowing multimodal imaging. The RTI process also can be used to form attenuation B-mode images.

Several factors affecting image quality are evaluated, including statistical fluctuations in the integral of the random backscatter and variations in backscatterer uniformity. Ex-vivo images of various organs illustrate RTI’s diagnostic potential.