The purpose of this paper is to describe key aspects of the integration and test of the Data Acquisition Electronics (DAE) in the PEM (Positron Emission Mammography) system. The main aspects highlighted are the methodology and strategies followed to test and validate the functionality and performance of the complete physical system. Test procedures are also described. These tests are controlled by the different FPGAs (Field Programmable Gate Array) that implement the DAE system functionality. Results of test and validation on FPGAs, boards and buses are presented.

The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A specialized gantry allows to perform exams of the breast and of the axilla. In this paper we present results of the measurement of detector modules that integrate the system under construction as well as the imaging performance estimated from Monte Carlo simulated data.

The Clear-PEM detector is a positron emission mammography scanner based on a high-granularity avalanche photodiode readout with 12 288 channels. The front-end sub-system is instrumented with low-noise 192:2 channel amplifier-multiplexer ASICs and free-running sampling ADCs. The off-detector trigger, implemented in a FPGA based architecture, computes the pulses amplitude and timing required for coincidence validation from the front-end data streams. A high-level C++ simulation tool was developed for data acquisition performance analysis and validated at bit-level against FPGA VHDL testbenches. In this work, simulation studies concerning the performance of the on-line/off-line energy and time extraction algorithms and the foreseen detector energy and time resolution are presented. Time calibration and trigger efficiency are also discussed.

The Clear-PEM detector system is a compact positron emission mammography scanner with about 12000 channels aiming at high sensitivity and good spatial resolution. Front-end, Trigger, and Data Acquisition electronics are crucial components of this system. The on-detector front-end is implemented as a data-driven synchronous system that identifies and selects the analog signals whose energy is above a predefined threshold. The off-detector trigger logic uses digitized front-end data streams to compute pulse amplitudes and timing. Based on this information it generates a coincidence trigger signal that is used to initiate the conditioning and transfer of the relevant data to the data acquisition computer. To minimize dead-time, the data acquisition electronics makes extensive use of pipeline processing structures and derandomizer memories with multievent capacity. The system operates at 100-MHz clock frequency, and is capable of sustaining a data acquisition rate of 1 million events per second with an efficiency above 95%, at a total single photon background rate of 10 MHz. The basic component of the front-end system is a low-noise amplifier-multiplexer chip presently under development. The off-detector system is designed around a dual-bus crate backplane for fast intercommunication between the system boards. The trigger and data acquisition logic is implemented in large FPGAs with 4 million gates. Monte Carlo simulation results evaluating the trigger performance, as well as results of hardware simulations are presented, showing the correctness of the design and the implementation approach

The design and evaluation of the imaging system Clear-PEM for positron emission mammography, under development by the PEM Consortium within the framework of the Crystal Clear Collaboration at CERN, is presented. The proposed apparatus is based on fast, segmented, high atomic number radiation sensors with depth-of-interaction measurement capabilities and state-of-the-art data acquisition techniques. The camera consists of two compact and planar detector heads with adequate field-of-view dimensions for breast and axilla imaging. Low-noise integrated electronics provide signal amplification and analog multiplexing based on a new data-driven architecture. The coincidence trigger and data acquisition architecture makes extensive use of pipeline processing structures and multi-event memories for high efficiency up to a data acquisition rate of one million events/s. Experimental validation of the detection techniques, namely the basic properties of the radiation sensors and the ability to measure the depth-of-interaction of the incoming photons, are presented. System performance in terms of detection sensitivity, count-rates and reconstructed image spatial resolution were also evaluated by means of a detailed Monte Carlo simulation and an iterative image reconstruction algorithm.

The purpose of this paper is to present the main aspects of a design and test (D&T) methodology used in the development of a specific type of system. The application focuses medical imaging using a compact positron emission mammography (PEM) detector with 12288 channels, targeting high selectivity and spatial resolution. The system operates at 100 MHz, with a data acquisition rate of 1 million events per second, under a total single photon background rate in the detector of 10 MHz. In this paper, the data acquisition electronics (DAE) system of the clear-PEM detector is used as vehicle for demonstrating the characteristics and versatility of the D&T methodology. For production and lifetime test, robust functional-oriented built-in self test (BIST) structures are developed. A design challenge in this context is the need to identify relevant data out of a huge amount of data streams. Another design challenge is the need to guaranty synchronism, without which data would become meaningless. Hierarchy, modularity, parallelism and pipelining are extensively exploited to meet these stringent system requirements. DAE implementation involves eight 4-million, one 2-million and one 1-million gate FPGAs (Xilinx Virtex II).

The main aspects of the design and test (D&T) of a reconfigurable architecture for the Data Acquisition Electronics (DAE) system of the Clear-PEM detector are presented in this paper. The application focuses medical imaging using a compact PEM (Positron Emission Mammography) detector with 12288 channels, targeting high sensitivity and spatial resolution. The DAE system processes data frames that come from a front-end (FE) electronics, identifies the relevant data and transfers it to a PC for image processing. The design is supported in a novel D&T methodology, in which hierarchy, modularity and parallelism are extensively exploited to improve design and testability features. Parameterization has also been used to improve design flexibility. Nominal frequency is 100 MHz. The DAE must respond to a data acquisition rate of 1 million relevant events (coincidences) per second, under a total single photon background rate in the detector of 10 MHz. Trigger and data acquisition logic is implemented in eight 4-million, one 2-million and one 1-million gate FPGAs (Xilinx Virtex II). Functional Built-In Self Test (BIST) and Debug features are incorporated in the design to allow on-board FPGA testing and self-testing during product lifetime.

First experimental results of the imaging system Clear-PEM for positron emission mammography, under development within the framework of the Crystal Clear Collaboration at CERN, are presented. The quality control procedures of crystal pixels, APD arrays and assembled detector modules are described. The detector module performance was characterized in detail. Results on measurements of light yield, energy resolution, depth-of-interaction and inter-channel cross-talk are discussed. The status of the development of the front-end electronics and of the data acquisition boards is reported.

The Clear-PEM detector system is a compact positron emission mammography scanner with about 12'000 channels aiming at high sensitivity and good spatial resolution. Front-end, Trigger and Data Acquisition electronics are crucial components of this system. Front-end system is implemented as a data-driven synchronous design that identifies and multiplexes the analogue signals (channels) whose associated energy is above a pre-defined threshold. The trigger and data acquisition logic uses digitized front-end data streams and computes the pulses amplitude and timing. Based on this information it generates a coincidence trigger signal that is used to initiate the conditioning and transfer processes of the corresponding data towards the data acquisition computer. To minimize dead-time, data acquisition electronics architecture makes extensive use of pipeline processing structures and de-randomizer memories with multi-event capacity. The system operates at 100 MHz clock frequency and is capable to sustain a data acquisition rate of 1 million events per second with efficiency above 95%, under a total single photon background rate of 10 MHz. The basic component of the front-end system is a low-noise amplifier-multiplexer chip presently under development. The off-detector system is designed around a dual-bus crate backplane for fast intercommunication among system modules. The trigger and data acquisition logic is implemented in large FPGAs with 4 million gates. Monte Carlo simulation results of the trigger efficiency, as well as results of hardware simulations are presented, showing the correctness of the design and implementation approach.