Maximum-likelihood calibration of small gamma cameras for 511 keV positron annihilation radiation

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Conference Proceeding

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The feasibility of employing maximum-likelihood (ML) position estimation in small scintillation cameras for use in FDG coincidence imaging was investigated. A small camera consisting of a Hamamatsu R-2487 position-sensitive photomultiplier tube (PSPMT) coupled to a single 8 mm thick NaI(Tl) crystal was calibrated with a tungsten and lead shielded 511 keV 18F source. The same calibration method has been previously employed at 140 keV using 99mTc. The source was positioned at each location of the image space to determine detector-signal distributions used in look-up table (LUT) generation. Corrected 511 keV point-array and flood images were obtained using the resulting 511 keV calibration LUT. Resolution was 2.0 mm - 2.5 mm full-width at half maximum (FWHM). This demonstrates that it may be feasible to use ML estimation to obtain accurate event positioning in similar imaging detectors employing more suitable scintillators.

Publication Source (Journal or Book title)

IEEE Nuclear Science Symposium & Medical Imaging Conference

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