A new modular detector for a cylindrical brain SPECT system

A new detector module has been developed for a prototype system, McSPECT II, which is being constructed for high-resolution clinical brain imaging. The detector module is the building block of the cylindrical detector system of the McSPECT II. Each detector module contains 5 NaI(Tl) bars and is backed by a glass window in an aluminum housing. Each detector module is associated with 6 PMTs to form a functional unit for position estimation. Bench-top tests performed on a sample unit demonstrated an average of 10.5% local energy resolution (ER) at 140 keV. Centroid calculations were applied in both orthogonal directions of the module for position estimation. In the longitudinal direction, a two-step centroid method yields a 13 cm UFOV (useful field-of-view) along the bar and an 11 cm CFOV (center FOV), with intrinsic spatial resolution of <5.5 and 3.8±0.3 mm FWHM, respectively. In the transverse direction, the task of identifying the bar detector involved in an event is simplified, with an accuracy better than 99% when photons are incident normally