High resolution detector modules based on NaI(Tl) arrays for small animal imaging

We are developing high spatial resolution detector modules based on recently available NaI(Tl) crystal scintillator arrays that are capable of detecting photons over a range of energies. We report on the testing of an array with individual element sizes of 1 mm/spl times/1 mm arrays over the energy range of 28 keV to 511 keV. It is anticipated that these detector modules could be applied to small animal imaging utilizing single photon emitters such as iodine-125 (28-35 keV) and technetium-99 m (140 keV); and also positron emitters such as fluorine-18. The performance of a 5 cm square array of NaI(Tl) crystal scintillators in which each element is 1 mm 1 mm x 5 mm in dimension was measured. The NaI(Tl) array manufactured by Saint-Gobain was coupled to Hamamatsu position sensitive photomultiplier tubes and tested over a range of photon energies. In particular, we tested the NaI(Tl) array with the Hamamatsu model R2487 position sensitive photomultiplier tube and the new Hamamatsu model 8500 flat panel position sensitive photomultiplier tube. Though the NaI(Tl) module performed best for the single photon emitters its use in positron emission tomography applications for small animal imaging could be possible even though resulting sensitivity is not ideal.