A comparative study of image reconstructions in SPECT and ultrasonic diffraction tomography

Single-photon emission computed tomography (SPECT) and ultrasonic diffracti on tomography (UDT) are tomographic imaging modalities that are based upon entirely different physical processes. In SPECT, from the measured intensit y of the electromagnetic wave (i.e., the gamma-ray), one seeks to determine the distribution of the gamma-ray emitter within an object. In UDT, from t he measured scattered fields (i.e., the scattered ultrasonic wave), one det ermines the refractive index distribution. However, in this work, we demons trate that the mathematics describing image reconstruction and the statisti cal analysis of image-noise properties are virtually identical for SPECT an d UDT. We also conducted computer-simulation studies, which quantitatively corroborated our theoretical analysis.