High resolution positron emission tomography with a prototype camera based on solid state scintillation detectors

The prototype of a high-resolution PET (positron emission tomography) camera consisting of two opposite arrays of detectors with independent solid-state readout was built and tested. The basic detector unit is the RCA C30994 detector module consisting of two 3-mm×5-mm×20-mm BGO scintillators, each coupled to one silicon avalanche photodiode. The two-dimensional stacking capability of the module allows a high-resolution multiring detection system to be assembled without crystal coding. The prototype was used to simulate a 31-cm-diameter dual ring tomograph suitable for animal studies. Coincident detector pair resolution was measured, and the contributions to resolution loss were estimated using a platinum-sheathed 0.75 mm ⁶⁸Ge line source. The intrinsic resolution is 1.9 mm FWHM (full width at half maximum), 3.5 mm FWTM at the center of the field. The reconstructed point spread function resolution in a stationary mode is 2.3 mm FWHM at the center and 3.1 mm FWHM (tangential), 3.9 mm FWHM (radial) 5 cm from the center. The axial resolution is less than 3.5 mm FWHM throughout the field. The ring sensitivity for an animal system is 67 kcps/mCi in air for an axial line source and 3.3 kcps/μCi/ml for a 10-cm-diameter cylinder of ²²Na solution