Front-end electronics for the RatCAP mobile animal PET scanner

We report on the development of the front-end electronics for rat conscious animal positron emission tomography (RatCAP), a portable and miniature positron emission tomography scanner. The application-specific integrated circuit (ASIC) is realized in a complementary metal-oxide-semiconductor 0.18 /spl mu/m technology and is composed of 32 channels of charge sensitive preamplifier, third-order semi-Gaussian bipolar shaper, timing discriminator with independent channel adjustable threshold, and a 32-line address serial encoder to minimize the number of interconnections between the camera and the data acquisition system. Each chip has a maximum power dissipation of 125 mW. A mathematical model of the timing resolution as a function of the noise and slope at the discrimination point as well as the photoelectron statistics was developed and validated. So far, three ASIC prototypes implementing part of the electronics were sent to fabrication. Results from the characterization of the first two prototypes are presented and discussed.