Silicon detector for a Compton camera in nuclear medical imaging

Electronically collimated gamma cameras based on Compton scattering in silicon pad sensors may improve imaging in nuclear medicine and bio-medical research. The work described here concentrates on the silicon pad detector for a prototype Compton camera. The silicon pad sensors are read out using low noise VLSI CMOS chips and novel fast triggering chips. Depending on the application a light weight and dense packaging of sensors and its readout electronics on a hybrid is required. The authors describe the silicon pad sensor and their readout on the newly designed hybrid. They also present a modular and low-cost data acquisition system (CCDAQ) based on a digital signal processor which is interfaced to the EPP port of widely available personal computers. Using the CCDAQ and the hybrids energy spectra of gamma-ray photons from technetium (₄₃^99mTc) an americium ( ₉₅²⁴¹Am) were acquired with an energy resolution of 2.45 keV FWHM for the 140.5 keV photo-absorption line of ₄₃^99mTc. For all pads the discrimination threshold in the trigger chip was between (15 and 25) keV