An application-specific integrated circuit for positron emission tomography

摘要

Improving the performance of positron-emission tomography (PET) systems for small animal imaging requires the use of high-speed detectors, such as a lutetium oxyorthosilicate (LSO) crystal coupled to avalanche photodiodes (APDs). We have developed an application-specific integrated circuit (ASIC) for reading out the multiple channels of an LSO-APD detector module for use in a small animal PET system. In this work, we characterize the performance of the ASIC, referred to as the AE172 chip. The AE172 can accommodate both positive and negative input signals, with a programmable conversion gain that ranges from 2.8 mV/fC to 21 mV/fC. The ASIC channels exhibit a linear response and an equivalent noise charge (ENC) of /spl sim/2000 electrons, RMS. The timing jitter depends on the amplitude of the input signal; and is less than 1 ns for test signals greater than 100,000 electrons. Connecting the ASIC to a linear APD detector reduces the relative readout noise to 26 electrons referenced to the input of the APD, which is operated at a gain of /spl sim/200. An LSO-APD-ASIC detector achieves an energy resolution of 13% for the 511 keV annihilation photons from a /sup 22/Na source, and a coincident timing resolution of /spl sim/13 ns.