A miniature phoswich detector for gamma-ray localization and beta imaging
A combined y-ray probe/imaging detector was created by modification of a beta imaging intra-operative probe. This phoswich detector consists of a thin CaF2(Eu) 1 imaging disk, coupled through a light diffuser to 7 or 19 parallelepiped highZ scintillation crystals arranged hexagonally in columns. These elements are either 2x2x10 mm3 or 4x4x10 mm3 LSO, GSO or BGO crystals, and act as both light guides for the imaging light and as intrinsic y detectors. The coincidence between the CaF2(Eu) and phoswich scintillators identifies + or trueevents and suppresses accompanying annihilation or background y events. The phoswich crystals are in turn coupled through optical fibers to a multi-channel PMT with positioning and discrimination electronics. Various characteristics of this novel imaging phoswich detector are investigated and presented for each of the phoswich combinations including: detector anisotropy, effects of time blocking and energy windows on phoswich imaging, intrinsic singles and phoswich spectral and spatial resolution characteristics, and phoswich imaging ability within y background environments. The performance characteristics of the assembled prototype devices demonstrate that in surgery, this device can be used three ways: (1) rapid localization of y emitting radionuclides with the modestly directional, self-collimated phoswich crystals; (2) high resolutionimaging or coarse (annihilation background corrupted) +imaging in singles mode; or (3) + imaging in coincidence mode with reduced y background contamination. © 1998 IEEE.
Tornai, MP; Levin, CS; MacDonald, LR; Holdsworth, CH; Hoffman, EJ
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