Study of the effect of energy window width and peak shift on SPECT images to evaluate false diagnosis

Introduction: The different factors that affect the camera uniformity of Single Photon Emission Computed Tomography (SPECT) technique have been analyzed including peak shift (%) and window width of energy. The effect of peak shift and window width on SPECT image uniformity has been investigated using a point source to perform intrinsic flood images. Methods:The relation between calculated integral & differential Center Field of View (CFOV) and Useful Field of View (UFOV) uniformity values were plotted with peak shift and window width change. The effects of window width of energy 5%, 10%, 15%, 20% and 25% on SPECT images were investigated using the 99mTc radioisotope with energy of 140 keV. Results:Although 0% shift is the optimum peak shift, but in the current research we have found that the data in the range of 0% to 2% peak shift provides result with satisfactory image quality. Integral Uniformity (IU %) and Differential Uniformity (DU %) values of CFOV and UFOV were noticeably changed with the change of energy window width. In this research, the optimum energy window width of the images of different flood phantom has been found to be in the range from 15% to 20%. Conclusion: Finally, 0% to 2% peak shift at 15% energy window width applied on heart phantom provides suitable images leading to proper diagnosis which conform our findings.