نوع مقاله : مقاله پژوهشی
1 دانشجوی کارشناسی ارشد، دانشگاه تربیت مدرس، تهران، ایران
2 دانشیار، دانشگاه تربیت مدرس، تهران، ایران
3 دانشجوی دکتری، دانشگاه تربیت مدرس، تهران، ایران
عنوان مقاله [English]
In this paper, we studied the effect of increasing number of projections in Myocardial SPECT from 32 to 64 while maintaining imaging time, on the final parameters of image quality using MonteCarlo simulation. Simulations performed by SimSET Monte Calro code on NCAT humanoid digital torso phantom. Three groups of images were simulated. First group with 32 projections and average 100k counts per view. The second group was simulated with 64 projections and average 50k counts per view for maintaining simulation time constant, and third group simulated with 64 projections but average 600k counts per view as reference. FBP method was use for reconstruction. Resolution, contrast and SNR parameters were calculated in each group and compared to each other. Increasing number of projections while reducing average counts per view, resulted to improvement of wall to cavity and wall to background contrasts. Reducing average counts per view caused a reduction in SNR value. In resolution comparison using FWHM, improvement was observed. According to FBP mathematical theory and effect of number of projections in reconstructed image, contrast enhancement was expectable. In nuclear medicine imaging, SNR would decrease by reducing the number of photons due to the statistical nature of radioactive decay. This reduction can cause some blurring in the reconstructed images that would be suppressed by increased number of projections. These phenomena leaded to resolution enhancement. It can be concluded that increasing in number of projection while decreasing number of photons could results enhancement in contrast and resolution.