Thermoacoustic tomography - Inversion of a spherical radon transform with partial data

Saturday, February 5, 2005 - 11:45am - 12:15pm
EE/CS 3-180
Sarah Patch (General Electric Corp., Research and Development Center)
Thermoacoustic tomography (TCT) is a hybrid imaging technique proposed as an alternative to xray mammography. Radiofrequency (RF) energy is deposited into the breast tissue uniformly in space, but impulsively in time. This heats the tissue causing thermal expansion. Cancerous masses absorb more RF energy than healthy tissue, creating a pressure wave which is detected by standard ultrasound transducers placed on the surface of a hemisphere surrounding the breast. Assuming constant sound speed, the data represent integrals of the tissue's RF absorptivity over a sphere centered about the transducers.

The inversion problem for TCT is to recover data from integrals over spheres centered on a hemisphere. We present an inversion formula for the complete data case, where integrals are measured for centers on the entire sphere. We will derive consistency conditions upon TCT data and discuss their implications for reconstructing clinically realizable 1/2-scan data sets.