8-Layer DOI encoding of 3-dimensional crystal array
8-Layer DOI encoding of 3-dimensional crystal array
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DOI：
10.1109/tns.2006.882795
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发表时间：
2006-10-01
影响因子：
1.8
通讯作者：
Nishikido, Fumihiko
中科院分区：
文献类型：
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作者：
Inadama, Naoko;Murayama, Hideo;Nishikido, Fumihiko
基于我们开发的四层互作用深度(DOI)探测器技术，设计了一种8层DOI探测器。新的探测器通过脉冲形状识别实现了8层DOI编码(2层DOI编码)，并在三维晶体阵列中优化了反射面布置(4层DOI编码)。通过一个8层10×10 Gd2SiO5(GSO)晶体阵列与256通道平板位置灵敏光电倍增管(256ch FP-PMT)的耦合，验证了它的性能。每个晶片的尺寸为2.90 mm×2.90 mm×3.75 mm，256ch FP-PMT的16×16多阳极间距为3.04 mm。在GSO中选择了两种不同掺杂浓度的GSO晶体进行脉冲波形识别：Ce掺杂量为0.5mol%和1.5mol%的GSO晶体的闪烁衰减时间分别为60 ns和35 ns。在晶体阵列中，离256ch FP-PMT最远的Layer-1、Layer-3、Layer-5和Layer-7由掺Ce量为0.5mol%的GSO晶体组成。其余各层均由掺杂量为1.5%Ce的GSO晶体组成。用662keV均匀伽马射线辐照8层DOI探测器，对探测器的性能进行了评价，评价为性能良好。为了证明层编码的有效性，将662keV伽马射线的扇束照射到每一层的侧面上。得到的二维位置直方图清楚地显示了相应层中的正确结构。对各层中心晶体的脉冲高度分布进行了测量，测量了各DOI层之间的光输出均匀性和能量分辨率。第二层和第三层晶体的光输出最小，其全能峰通道是第八层晶体分布的最大峰值通道的62%。所有八层的能量分辨率约为15%。
An 8-layer depth of interaction (DOI) detector was designed based on the technique we have developed for 4-layer DOI detectors. The new detector achieves 8-layer DOI encoding by pulse shape discrimination (2-layer DOI encoding) and an optimized reflector arrangement in a 3-dimensional crystal array (4-layer DOI encoding). Its capability was proved with an 8-layer 10 x 10 Gd2SiO5 (GSO) crystal array coupled to a 256-channel flat panel position sensitive photomultiplier tube (256ch FP-PMT). The dimensions of each crystal element were 2.90 mm x 2.90 mm x 3.75 mm and the interval between 16 x 16 multi anodes in the 256ch FP-PMT was 3.04 mm. Two different dopant concentrations in GSO were chosen for pulse shape discrimination: GSO crystals of 0.5 mol% and 1.5 mol% Ce dopant that have 60 ns and 35 ns scintillation decay times, respectively. In the crystal array, Layer-1, the farthest from the 256ch FP-PMT, and Layers-3, -5 and -7 were composed of GSO crystals of 0.5 mol% Ce dopant. All other layers were composed of GSO crystals of 1.5 mol% Ce dopant. Performance of the 8-layer DOI detector was evaluated by irradiating with 662 keV uniform gamma-rays and the capability was judged to be good. To prove the validity of the layer encoding, a fan-beam of 662 keV gamma-rays was irradiated onto the side face of each layer. The obtained 2-dimensional position histograms showed the right structure in each corresponding layer clearly. Light output uniformity among DOI layers and energy resolutions were measured on the pulse height distributions of the central crystal in each layer. The crystals in Layer-2 and Layer-3 showed the smallest light output and their full energy peak channels were 62% to the largest peak channel of the Layer-8 crystal distribution. Energy resolutions were about 15% for all eight layers.