Image reconstruction FPGA prototype applied to a mini gamma camera

In this work a read out electronics prototype for reconstruction of two-dimensional images based on Field Programmable Gate Arrays (FPGAs) is presented. The front-end includes two main modules, the data acquisition electronics and a hardware architecture for data processing. The read out electronics consists mainly of a Resistive Chain, analog-to-digital converters and a FPGA Virtex IV of the Xilinx´s family. This module reads the electrical signals produced by a position-sensitive photomultiplier tube (PS-PMT) coupled to a cerium-doped lutetium yttrium orthosilicate (LYSO) crystal. The hardware architecture takes the digitized signals produced by the acquisition module and processes them to determine the position of the interactions based on the Anger logic to form a planar image. The hardware architecture performs arithmetic operations, formats and stores the data in order to send them to the displaying stage. The resulting image represents a 2D histogram for the intensity distribution of the radioactivity. Both systems interact to operate at a clock frequency of 322 MHz reducing the processing time to reach real time performance. Using parallel techniques and an appropriate management of memory, the necessary logic to implement the system has been developed improving flexibility for adjustment to new requirements or new algorithms. The main contribution of this work consists on validating the use of a FPGA in the image processing stage in a nuclear medicine application, such as the Gamma Camera.