Ultrasonic B-scanning: a Computer Simulation

A method has been developed which can predict the appearance and properties of B-scan images. The theoretical basis for the tissue models used, and the assumptions made in the simulation concerning the nature of pulse-echo imaging, are discussed. A key feature of the simulation is the Fourier domain synthesis of the tissue model, which permits convenient specification of some statistical properties of a randomly inhomogeneous scattering medium. Other characteristics that may be specified include the ultrasonic pulse and beam shapes, and subsequent signal processing. Both the initial tissue model and the simulated B-scan image are displayed as grey-scale pictures, allowing visual comparison in the same way that clinical B-scans are currently observed. Preliminary results of applying the simulation are shown to have a number of features in common with clinical images and with scans of a test object. A better understanding of the nature of pulse-echo images is gained and conclusions drawn regarding the range of system and tissue parameters over which these images convey information about the tissue structure. The method may also be of use to determine optimum design of equipment for imaging and tissue characterisation, and to investigate the extent to which the acoustic structure of tissues can be described in terms of simple mathematical models.