Crosstalk Effect in Medical Ultrasound Tomography Imaging

Ultrasound tomography (UT) is a modern method of medical imaging that has been intensively developed recently to diagnose female breasts in vivo. This method makes it possible to acquire images in various ultrasound modalities simultaneously - both transmission and reflection ones, without any focusing. Therefore, the ultrasound intensity level when scanning individual coronal breast sections is relatively low. Data for reconstruction of images is obtained by means of a multi-element array of small piezoceramic transducers spaced evenly on the inner side of the ring surrounding the breast immersed in water. The main problem with such arrangements is the occurrence of crosstalk, which introduces specific errors to measurement data. Crosstalk is a result of a deficiency in electrical or mechanical isolation between array elements. Such errors lead to distortions in the reconstructed images. In the paper, the effect of crosstalk in the ultrasound tomography ring array was examined and analyzed. The influence of crosstalk on the reconstructed images of the breast structure was shown as well. Conducted studies enabled the detection of the sources and paths of crosstalk and, as a consequence, it allowed us to improve the design of the multi-element ultrasonic transducer ring array, and to reduce crosstalk.