Axial Resolution of Helical-Orbit Pinhole SPECT With Synchronized and Unsynchronized Motion

Pinhole SPECT imaging is widely used in small-animal imaging. Helical orbits provide better sampling and axial resolution compared to circular ones; however, the unsynchronized axial translation of the imaged object and the camera rotation may cause blurring in the image resulting in poorer resolution. In this study, we investigated the axial resolution for synchronized and unsynchronized motions with a small phantom (Ultra-Micro-Defrise) that closely mimics the size of a mouse. We applied angular-dependent axial mechanical shift corrections that substantially improved axial resolution in this regime. Further, we developed custom-designed electronic circuitry to achieve synchronization of the SPECT scanner and the imaged object. The results show that synchronized motion improves axial resolution especially when the angular step of the scanner's rotation is large.