Aperture optimization for 3D ultrasound computer tomography

At Forschungszentrum Karlsruhe an ultrasound computer tomograph is developed for breast imaging in 3D. The aim of this project is the support of early diagnosis of breast cancer. Our current setup consists of a cylindrical tank assembled with 384 emitter and 1536 receiver elements which are grouped to 48 rectangular transducer array systems (TAS). It has been shown in previous work that the cylindrical aperture has major drawbacks in the vertical resolution. Given a new square TAS pattern with 4 emitters and 9 receivers, a new aperture for 160 TAS is derived which optimizes the image quality regarding three criteria. The optimization criteria regard the resolution of this 3D imaging system, the image contrast and utilization of the available ultrasound energy. An optimization with equal weighting of these criteria resulted in an 40% improvement of the resolution regarding the size and isotropy compared to the current cylindrical aperture. The resolution could be improved by 40% regarding the size and isotropy. Yet the contrast is degraded by 13%. Further work will be to find a reasonable weighting of the the three criteria. It could be shown that the presented method for aperture optimization makes this high-dimensional optimization problem feasible. The most important physical parameters like tissue attenuation, beam profile and scatterer profile, could be included to increase the authenticity of the results.