Study Of The Spatial-Resolution In Gamma-Detectors Using Photosensitive Wire Chambers In View Of Their Use As High-Resolution Pet Scanners

The spatial resolution in gamma detectors using BaF2 scintillators and photosensitive wire chambers was studied for 511 keV gamma rays with different crystal geometries. When a matrix of small crystals was used, the spatial resolution was dominated by the crystal dimensions. With crystals measuring 3 x 3 x 20 and 2 x 2 x 15 mm3 and with 0.3 mm dead space between them, we obtained a resolution FWHM of 3.7 and 3.0 mm, respectively. With one large crystal 20 mm thick a resolution of 7.9 mm FWHM was obtained. We used a Monte Carlo study to evaluate the performances of a high resolution PET scanner for small animals based on this principle. Such a device is presently under construction.