FPGA-Only MVT Digitizer for TOF PET
FPGA-Only MVT Digitizer for TOF PET
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适用于 TOF PET 的仅 FPGA MVT 数字化仪
DOI：
10.1109/tns.2013.2277855
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发表时间：
2013-10-01
影响因子：
1.8
通讯作者：
Xie, Qingguo
中科院分区：
文献类型：
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作者：
Xi, Daoming;Kao, Chien-Min;Xie, Qingguo
多电压阈值（MVT）方法是我们提出的一种通过相对于特定参考电压进行采样来数字化PET事件脉冲的方法。以前，我们已经实现了这种方法，通过使用离散电压比较器连同离散时间数字转换器（TDC）或TDC上实现的现场可编程门阵列（FPGA），并表明该方法是有用的发展PET探测器能够飞行时间（TOF）测量。在本文中，我们研究了一种仅FPGA实现，其中在低电压差分信号（LVDS）接收器模式下工作的FPGA的差分I/O被配置为提供电压比较器的功能。使用Altera Cyclone II系列FPGA（EP 2C 70 F896 C7），我们构建了两个MVT数字化通道，每个通道包含四个比较器，为每个事件脉冲产生八个样本。我们描述的设计，实施和校准的FPGA只MVT数字化仪，并报告其性能特性。通过将通道连接到SensL的硅光电倍增管（SiPM）FM 30035，该硅光电倍增管（SiPM）FM 30035耦合到2 x 2 x 10 mm（3）LYSO晶体，我们测量了类似于16%的能量分辨率（在511 keV）和类似于500 ps（FWHM）的符合分辨时间（CRT）。这些分辨率对于开发PET和TOF PET探测器是有希望的。另一方面，基于通过使用50千兆采样每秒（Gsps）数字示波器（Tektronics DPO 71604 B）获得的由相同SiPM和LYSO产生的脉冲的数字化波形，我们测量了能量分辨率和类似于9%的CRT以及类似于390 ps的CRT。比较表明，我们目前实现的FPGA的MVT数字化仪有助于类似的13%的能量分辨率和类似的310 ps CRT。
The multi-voltage threshold (MVT) method, proposed by us, is a method for digitizing a PET event pulse by sampling with respect to certain reference voltages. Previously, we have implemented this method by using discrete voltage comparators together with discrete time-to-digital converters (TDCs) or TDCs implemented on a field-programmable-gate-array (FPGA), and shown that the method is useful for developing PET detectors capable of time-of-flight (TOF) measurement. In this paper, we investigate an FPGA-only implementation in which the differential I/Os of the FPGA operating in the low-voltage-differential-signaling (LVDS) receiver mode are configured to provide the function of the voltage comparators. Using an Altera Cyclone II Family FPGA (EP2C70F896C7), we built two MVT digitizing channels, each of which contains four comparators to yield eight samples for each event pulse. We describe the design, implementation and calibration of this FPGA-only MVT digitizer and report its performance properties. By connecting the channels to SensL's silicon photomultipliers (SiPMs) FM30035 coupled to 2 x 2 x 10 mm(3) LYSO crystals, we measured an energy resolution of similar to 16% (at 511 keV) and a coincidence resolving time (CRT) of similar to 500 ps (FWHM). These resolutions are promising for developing PET and TOF PET detectors. On the other hand, based on digitized waveforms of pulses generated by the same SiPMs and LYSOs acquired by using a 50 giga-sample-per-second (Gsps) digital oscilloscope (Tektronics DPO71604B), we measured an energy resolution of and a CRT of similar to 9% and a CRT of similar to 390 ps. The comparison suggests that our current implementation of the FPGA-only MVT digitizer contributes an similar to 13% energy resolution and similar to 310 ps CRT.