Performance characteristics of a compact position-sensitive LSO detector module

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We assembled a compact detector module comprised of an array of small, individual crystals of lutetium oxyorthosilicate: Ce (LSO) coupled directly to a miniature, metal-can, position-sensitive photomultiplier tube (PSPMT).We exposed this module to sources of 511-keV annihilation radiation and beams of 30- and 140-keV photons and measured spatial linearity; spatial variations in module gain, energy resolution, and event positioning; coincidence timing; the accuracy and sensitivity of identifying the crystal-of-first-interaction at 511 keV; and the effects of intercrystal scatter and LSO background radioactivity. The results suggest that this scintillator/phototube combination should be highly effective in the coincidence mode and can be used, with some limitations, to image relatively low-energy single photon emitters. Photons that are completely absorbed on their first interaction at 511 keV are positioned by the module at the center of a crystal. Intercrystal scatter events, even those that lead to total absorption of the incident photon, are placed by the module in a regular “connect-the-dot” pattern that joins crystal centers. As a result, the accuracy of event positioning can be made to exceed 90%, though at significantly reduced sensitivity, by retaining only events that occur within small regions-of-interest around each crystal center and rejecting events that occur outside these regions in the connect-the-dot pattern.
Intercrystal scatter, Lutetium oxyorthosilicate:Ce (LSO), Position-sensitive photomultiplier tubes, Small animal positron emission tomography (PET)
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IEEE Transactions on Medical Imaging, vol. 17, n. 6, dec. 1998. Pp. 967-978