Half-millimeter animal SPECT imaging on a clinical SPECT scanner with highly flexible collimator design

In order to develop animal SPECT imaging technology on clinical SPECT scanners, we propose a highly flexible multi-pinhole collimator design scheme. The proposed design allows individual adjustment of important system parameters, so that the collimator device is adaptable to various SPECT systems, and one can also optimize different specific aspects of system performance (e.g. improving spatial resolution, maximizing sensitivity or increasing FOV) for different application purposes. This work is focused on achieving half-mm SPECT imaging resolution on a single-head clinical SPECT scanner. A seven-pinhole collimator and a four-degree-of-freedom motion control stage are assembled. High accuracy geometrical calibration is performed by scanning a point source in a hybrid orbit, which consists of three circular orbits in different axial positions and a helical orbit. The system matrix is derived from Monte-Carlo simulation and de-noised by fitting each point spread function (PSF) to a 2D Gaussian function. Dual-point-source studies show that 0.5 mm reconstruction resolution is achievable in the studied system. Preliminary ultra micro hot rod phantom experiments demonstrate 0.6 mm hot rods are identifiable clearly. The proposed technology is attractable for its low cost, high flexibility, high feasibility and reproducibility.