SETIT 2004 International Conference: S ciences of E lectronic, Technologies of I nformation and Telecommunications March 15-20, 2004 – TUNISIA Gamma Camera Interface System Based on FPGA B. Mahmoud 2 , M.-H. Bedoui 1 , R. Raychev 1 , H. Essabbah 1 1 Laboratoire de Biophysique, Faculté de Médecine de Monastir - 5019 Monastir – Tunisie 2 Institut Supérieur de Musique de Sousse – Tunisie Bouraoui.Mahmoud@fsm.rnu.tn Abstract — We have carried out an interface system for semi-analog Gamma Camera. It consists of an Image Acquisition, Treatment and Display chain (IATD) ensuring the acquisition and the treatment of the signals resulting from the detection head. This chain is formed by a treatment analog board and a digital treatment board designed around a DSP (Digital signal Processor). In this paper we have described a new version of this system in which we have improved the performance and the flexibility of the digital part by using a specific reprogrammable FPGA (Field Programmable Gate Array) circuit. Key Words: — Gamma camera / Spectrometry / Linearity / DSP / FPGA . 1 INTRODUCTION The evolution in the technology of the integrated circuit contributes to a migration of the Gamma Camera design towards simpler and more preferment ones. Most recent are the digital cameras where the digitalization is done directly on each Photomultiplier’s (PM) output, a local event detection. The former generation which continues to equip much nuclear medicine services is that known as hybrid camera. It is an "Anger pseudo camera". We haven’t access to the PM output signal but to a signal resulting from a signals summation of all the PMs, a total event detection [1]. In this category we distinguish, according to the treatment held by the electronics of the Detection Head (DH), two types of Gamma Cameras. In the first, called analog gamma camera, the DH generates two position signals (X, Y) and an energy signal (E), all analogical. In the second, called semi-analog gamma camera, the DH generates an energy signal (E) and four position signals (X + ,X - ,Y + ,Y - ), all analogical. To make this generation profit from hybrid camera of advanced data-processing tools for treatment of the images without calling to an acquisition station suggested high- cost by the constructor and provided with closed software, we made an interface for semi-analog cameras of Sopha Medical Vision (SMVi) by taking as example SOPHY DS7 of the year 1989. The developed system consists of an Image Acquisition, Treatment and Display (IATD) ensuring the acquisition and the treatment of the signals resulting from the DH. The developed chain is formed by a treatment analog board and a digital treatment board designed around a DSP [2]. In this paper we have presented the architecture of a new version of our chain IATD in which the integration of the treatment algorithms is executed on an FPGA (Field Programmable Gate Array) circuit. 2 MATÉRIELS AND MÉTHODES 2.1 System’s architecture Figure 1: System Architecture Organ to be investigated γ Y X TD ADC Pile-up phenomenon Useful information Gain and offset compensation Digital block