Development of a DSP-based real-time position calculation circuit for a beta camera

A digital signal processor (DSP)-based position calculation circuit was dev eloped and tested for a beta camera. The previous position calculation circ uit which employed flash analog-to-digital (A-D) converters for A-D convers ion and ratio calculation produced significant line artifacts in the image due to the differential non-linearity of the A-D converters. The new positi on calculation circuit uses four A-D converters for A-D conversion of the a nalog signals from the position sensitive photomultiplier tube (PSPMT). The DSP reads the A-D signals and calculates the ratio of X-a/(X-a + X-b) and Y-a/(Y-a + Y-b) on an event-by-event basis. The DSP also magnifies the imag e to fit the useful field of view (FOV) and rejects the events out of the F OV. The line artifacts in the image were almost eliminated. (C) 2000 Elsevi er Science B.V. All rights reserved.