Comparison of Continuous Step-and-Shoot versus Step-and-Shoot Acquisition SPECT

This study compared the quality of SPECT images obtained with step-and-shoot mode (SSM) and continuous step-and-shoot mode (CSSM). Methods : Computer simulations of SSM and CSSM were performed with a two-dimensional Shepp-Logan head phantom and a high-resolution parallel-hole collimator. The effects of noise and photon attenuation were examined. Results : Without noise and without attenuation, small structures in reconstructed images obtained using fast CSSM (less than 4 sec per view plus the moving time from one view to the next) were slightly blurred and rotated in the opposite direction of detector motion. With both noise and attenuation, these artifacts were not visible, and the image quality obtained from CSSM, especially from fast CSSM, was improved as compared to that resulting from the corresponding SSM due to the increasing number of counts. The improvement of image quality became less significant with increasing acquisition time and in the presence of attenuation. Conclusion : For fast SPECT, CSSM provided better image quality than the corresponding SSM, especially when attenuation effects were not present. For relatively long time SPECT without attenuation compensation that is typical for clinical studies, the image quality of CSSM was similar to that of SSM.