FPGA-based multichannel data acquisition system for prototype in-beam PET

Abstract

In-beam positron emission tomography (PET) is a clinically proven imaging technique for the online investigation of position emitters induced by hadron irradiation. Because the PET involves the use of many photodetectors, the data acquisition (DAQ) system of the PET system requires many elements and a high processing speed to handle many input signals and complex data sets simultaneously. To create a fast and compact DAQ system for a prototype in-beam PET system, we used an FPGA-based multichannel analysis board and developed a firmware program that was geared to acquire the prototype in-beam PET data. As a result, a flood map of the detector block with <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na 10μCi sources was acquired, and all pixels were well separated. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> F-FDG (4-mm diameter, 3 mCi), which was located in the center of a PET ring, was explored to acquire preliminary results from the prototype in-beam PET system. We produced an energy histogram with an energy resolution of 26% at 511 keV and a reconstructed point image. The measured maximum count rate on the host PC using the developed DAQ system was 120,000 cps. Although there were many improvements in terms of the count rate, the calculation of the pulse timing and correction methods can still be improved, and we were able to assess the feasibility of the prototype in-beam PET system from the achieved preliminary results.