RF diffraction effect in RF-induced thermoacoustic tomography: calibration and distortion

Because the wavelengths of radio-frequency (RF) waves used in thermoacoustic tomography (TAT) are comparable with the size of detected objects, RF diffraction plays important roles in TAT. The RF diffraction affects not only the global distribution of the RF field in the tissue, but also local RF energy deposition. In this paper, we discussed these two major effects. Both numerical simulations and phantom experiments are done to demonstrate these phenomena. We also provide a partial correction method for the image distortion and a calibration algorithm for image calibration.