Identification And Correction Of Artifacts On SPECT Image

The mechanism of artifact in SPECT image and the techniques of identification and correction were systematically described in this thesis. Five studies on artifact identification and correction were reported.1. Study on improving image quality with transmission attenuation correction [OBJECTIVE] A ¹⁵³Gd scanning line source transmission attenuation correction system (TAC) of SPECT was evaluated with phantoms and patients. [METHODS] (1) Phantom acquisition: Jaszczak phantom inserted with six rods and myocardial phantom, filled with ^99mTc or ²⁰¹T1 solution, was imaged with or without TAC respectively. (2) Patient acquisition: the total number of 86 patients, 39 with ²⁰¹Tl and 57 with ^99mTc-MIBI, were carried out myocardial perfusion tomography with TAC. (3) Phantom result analysis: A profile of the cross transverse slice across the phantom was drawn to calculate uniformity and contrast. The count ratios between anterior and posterior wall, septal and lateral wall in the short axis slice of the myocardial phantom were calculated. (4) Patient result analysis: The reconstructed images were diagnosed and evaluated by the nuclear medicine specialists. [RESULTS] The profile of the Jaszczak phantom showed that the attenuation of the image was well corrected, therefor the contrast of the image was improved in deep location lesions. The count ratios of the myocardial phantom were increased after attenuation correction. The results of the patient study showed that the image quality were significantly different with and without attenuation correction, but the effects of the correction for ^99mTc was better than ²⁰¹Tl. [DISCUSSIONS] This study on TAC was specially designed for myocardial perfusion imaging, so it works well for the organs in the deep location of the body, for instance, Heart, but it is not suitable to the organs, which are near the surface of the body. [CONCLUSIONS] TAC can effectively compensate reduction of the photon flow caused by the attenuation of the human body and improve image contrast and diagnosis accuracy in the deep location lesions.2. Effect of patient motion on dual head tomographic myocardial perfusion [OBJECTIVE] To evaluate the effect of patient motion on dual head tomography and compare the differences of the effects between single head SPECT and dual head SPECT. [METHODS] By setting the heads of the dual-head SPECT in 90 degrees orientation, a 90 degrees tomographic myocardial perfusion image was acquired on dual head and a 180 degrees image was acquired on single head (closed another head). During data acquisition the myocardial phantom was moved...