Development of Two-Dimensional PVDF Arrays for Transmission Computed Tomography of Attenuation

Diffraction, refraction and reflection of the ultrasonic beam interrogating tissue are major causes of artifacts in transmission ultrasonic comupted tomography (UCT) of the female breast. Large aperture receiving arrays and phase insensitive signal processing have been shown to reduce those errors dramatically in the scanning plane. To avoid errors from refraction perpendicular to the scanning plane, two dimensional matrix arrays are necessary. Aspects of the phase insensitivity provided by two signal processing schemes for evaluating attenuation with an array receiver have been explored. Several two-dimensional PVDF arrays have been fabricated and initial testing of single-element directivity patterns has been measured. Construction of 2-D arrays with the element density required for minimizing UCT refraction artifacts is now possible.