Phantom Experimentation on SPECT, Infrared and Optical Tomography

The Single Photon Emission Computed Tomography (SPECT) using simple γ - radiotracers has been established as a standard technique in the physiological and functional nuclear imaging. On the other hand, accurate reconstruction of abnormalities inside biological tissues based on the detected temperature distribution obtained at the surface of the skin presents a major challenge in emission thermography. The present work focuses on the experimental study with these modalities using appropriately constructed 99 Tc and thermal phantoms. Special emphasis was given to the relationship between the physical characteristics, such as the location and the emission power of an embedded heat source inside an absorbing medium and the measured temperature distribution by means of infrared imaging. Those thermal phantoms were studied at temperature 35 0 − 40 0 C, which corresponds to mammal’s core temperature. The obtained planar information was further analyzed to reconstruct the tomographic images, and from them, the final 3D image of the phantoms. The reconstruction procedure was performed with iterative algorithms based on MLEM and accelerated ART techniques. In order to investigate scattering and absorption effects, the same reconstruction procedure has been applied to optical (fluorescence) tomography with appropriately constructed phantoms. Recon- structions results are presented in this study for different phantom depth locations and heat generation rates.