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

To improve the spatial resolution of small field-of-view gamma camera composed of a NaI(Tl) scintillator and a position sensitive photo-multiplier tube (PSPMT). An NaI(Tl) scintillator with fiber plate light output was tried and was compared the performance with that with conventional glass plate light output. Since the fiber plate limits the scintillation light distribution and make it narrower, spatial resolution is improved. Using the 20 mm×20 mm, 2 mm thick NaI(Tl) scintillators with glass plate and with fiber plate light outputs, performance was measured and compared. Using the fiber plate, the scintillation light output was 35% smaller than that with glass plate. The average spatial resolution with fiber plate was 0.98 mm FWHM while that with glass plate was 1.67 mm FWHM for 122 keV Co-57 gamma photons. Although the light output was decreased, the spatial resolution was dramatically improved. These results indicate that the NaI(Tl) with fiber plate light output is promising for PSPMT based small field-of-view gamma cameras.