The ClearPET/spl trade/ data acquisition

Abstract

Within the Crystal Clear Collaboration a modular system for a small animal PET scanner (ClearPET TM ) has been developed. The modularity allows the assembly of scanners of different sizes and characteristics in order to fit the specific needs of the individual member institutions. Now a first demonstrator is being completed in Jülich. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to multi-channel photomultipliers (PMTs). A free-running ADC digitizes the signal from the PMT and the complete scintillation pulses are sampled by an FPGA and sent with 20 MB/s to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. An advantage of that is that the coincidence window and the dimensions of the field of view can be adjusted easily.The ClearPET TM demonstrator is equipped with 10240 crystals on 80 PMTs. This paper presents an overview of the data acquisition system.

A cross-correlation method for crystal identification in APD-based phoswich detectors used in small animal PET scanner

“…Among these methods, the pulse shaping discrimination (PSD), which is sensitive to noise, uses temporal or frequency features of the extracted signal for identification [3]. On the other hand, the auto-regressive with exogenous variable (ARX) model [4] or its fast version, the auto-regressive (AR) model [5,6], extract the decay time by using an adaptive filter.…”

System Integration of the LabPET Small Animal PET Scanner

“…However, new multi-crystal detector modules used in medical imaging require flexible and adaptive detection schemes that analog circuitry can hardly provide. On the other hand, the increased processing power in recent digital programmable electronics allows designers to build systems with either fully digital [1][2][3][4][5] or mixed analog/digital [6] signal analysis. Such scanners can correctly extract and refine parameters from events of interest even in noisy environments.…”

“…Tétrault Complete data recording allows maximum flexibility for data analysis [4,5], but is impractical for real-life imaging protocols. These require real-time signal processing to minimize file size and post-acquisition processing delays.…”

Wavelets-Based Crystal Identification of Phoswich Detectors for Small-Animal PET

“…All those problems can be addressed with crystal identification (CI) from phoswich detectors [2]. Current CI techniques rely mainly on two methods: Pulse Shape Discrimination (PSD) [3,4] and advanced digital signal processing [5,6]. PSD methods use temporal or frequency information (Fourier's analysis) for CI [4].…”

“…Current CI techniques rely mainly on two methods: Pulse Shape Discrimination (PSD) [3,4] and advanced digital signal processing [5,6]. PSD methods use temporal or frequency information (Fourier's analysis) for CI [4]. Although there are quite easy to implement, there are also fairly sensitive to noise and, most of the time, limited to specific crystal pairs with rather different characteristics.…”