Resolution improvement using a fiber optic plate for a small field-of-view NaI(Tl) gamma camera

To improve the spatial resolution of a small field-of-view gamma camera composed of a NaI(Tl) scintillator and a position sensitive photo-multiplier tube (PSPMT), the performance of an NaI(Tl) scintillator with a fiber optic plate for a light output was compared with that of such a scintillator using a conventional glass plate. Since the fiber optic plate limits the light distribution and makes it narrower, spatial resolution is improved. Using 20×20 mm, 2-mm-thick NaI(Tl) scintillators with a glass plate and with a fiber optic plate, performance was measured and compared. Using the fiber optic plate, the scintillation light output was 35% less than with a glass plate. The average spatial resolution with the fiber optic plate was 0.98-mm full width at half maximum (FWHM) while that with the glass plate was 1.48 mm FWHM for 122-keV, Co-57 gamma photons. Although light output decreased, spatial resolution dramatically improved. These results indicate that the NaI(Tl) with a fiber optic plate for light output is promising for PSPMT-based small field-of-view gamma cameras.