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A new high energy scintillating fiber optic single photon computed tomography detector
Author(s) -
Monroe James I.
Publication year - 2000
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.599039
Subject(s) - collimator , detector , optics , scintillator , physics , full width at half maximum , collimated light , image resolution , photon , materials science , medical physics , laser
A new detector for imaging annihilation radiation is designed as an auxiliary unit for single photon computed tomography (SPECT) systems. Increased interest in higher energy medical imaging creates a demand for a low cost device that can be used with existing SPECT units. Key design features are: a custom high‐resolution collimator, a scintillator formed from plastic optical fibers, and a position‐sensitive photomultiplier. The optical fiber core is a ternary scintillator: Polystyrene (solvent) with solutes PPO and BS–MSB. High‐energy resolution (7.5 mm full‐width at half max (FWHM) at a source‐to‐collimator distance of 10 cm), improved total efficiency( 2.7 × 10− 5at a SCD of 10 cm), and low cost are hallmarks of the new detector. The FWHM is more than twice that available imaging 511 keV gammas with conventional SPECT cameras. Images are formed using Compton electrons, which are limited to one interaction inside the detector as opposed to detection by photoelectric interactions in conventional cameras. Computer simulations with the radiation transport code EGS4 verified the basic imaging concept and were then used to optimize the detector and collimator designs. A working prototype detector was manufactured, tested, and characterized. Positron emitting Germanium‐68 (Ge‐68) was used as a laboratory point source of annihilation radiation for testing. A larger area detector (4×4 array of 16 identical modules, each 5 cm ×5 cm ×20 cm with an expected planar sensitivity of4 × 10− 4) specifically for augmented breast cancer diagnosis was then proposed and simulated as a possible application of this technology.