| The subject of this dissertation is the development of corrections for physical problems that limit the accuracy of tomographic images used in diagnostic nuclear medicine. These limitations can, and sometimes do lead to incorrect diagnosis by the nuclear medicine physician. These problems either deal with the basic interactions of photons with matter, or are intrinsic to the imaging process. Corrections have been developed to compensate for the following problems: (1) Compton scatter, (2) Photon attenuation (due to the photoelectric effect), and (3) Finite resolution effects.;A method of scatter compensation has been investigated that subtracts counts in an energy window that primarily contains Compton scattered photons from the counts obtained from a photopeak energy window. A novel nonuniform attenuation correction methodology has been proposed and investigated that used a transmission scan to construct an attenuation map of the patient. Attenuation coefficients are assigned to areas defined in this map and used in the construction of an attenuation correction map. A three-dimensional convolution model has been developed to investigate finite resolution effects in tomographic imaging. This model has been used to develop corrections for these resolution effects in situations where the geometry of the radionuclide distribution is known. A combined methodology has been developed which incorporates aspects of the corrections for Compton scatter, attenuation, and finite resolution effects. |
