A comparison of performance of three gamma camera systems for positron emission tomography

The development of coincidence positron imaging using a gamma camera should significantly increase PET utilization. This study has compared the performance of three such systems with each other and with an equivalent single photon emission computed tomography (SPECT) measurement. A Carlson phantom, which consisted of a 20 cm diameter cylinder containing areas of uniform activity, hot lesions, cold lesions and orthogonal alternate hot and cold lines, was filled with an activity of 18F chosen to try and best exploit each camera and imaged for a fixed time (27 min). The image quality of 9 mm thick slices in each section of the phantom was compared visually. Several image quality parameters were also compared including line source resolution and noise equivalent count rate. There were considerable differences in PET image quality between the three cameras but all were at least as good as the SPECT image. The full width at half maximum (FWHM) resolution of all systems was similar (approximately 4.5 mm) but the maximum noise equivalent count rates in a 20 cm cylinder were significantly different (6.3, 2.6 and 1.6 kcps) (where cps is counts per second) and correlated with the phantom image quality.