Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding
Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding
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DOI：
10.1118/1.4890609
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发表时间：
2014-08-01
期刊：
影响因子：
3.8
通讯作者：
Pichler, B. J.
中科院分区：
文献类型：
--
作者：
Kolb, A.;Parl, C.;Pichler, B. J.
目的：本研究的目的是开发用于小动物正电子发射断层扫描和磁共振成像 (PET/MR') 组合系统的原型 PET 探测器模块。小动物成像应用最重要的因素是 PET 相机的检测灵敏度，可以通过使用更长的闪烁晶体来优化检测灵敏度。同时，小动物 PET 系统必须具有高空间分辨率。由于高场动物 MR 扫描仪的孔径有限，被测物体距离 PET 探测器非常近。当与长闪烁晶体结合使用时，这些小口径 PET 系统会产生视差误差，最终导致空间分辨率下降。因此，我们开发了一种交互深度（DoI）编码PET探测器模块，该模块在整个视场（FOY）上具有统一的空间分辨率、高探测灵敏度、紧凑性和对磁场不敏感。方法：该方法基于具有交叉带编码的盖革模式雪崩光电二极管（G-APD）探测器。对于所选块元件，读出通道的数量减少了 36 倍。将两个 12 x 2 G-APD 条形阵列（25 gm 单元）垂直放置在 12 x 12 氧原硅酸镥晶体块的每个面上，晶体尺寸为 1.55 x 1.55 x 20 mm。带状阵列被复用到两个通道中，并用于计算每个阵列的 x、y 坐标和沉积能量。 DoT 是通过准直 18F 光源以 1.8 mm 的步长测量的。通过采集每个事件的波形并应用数字前沿鉴别器，对所有 DoT 位置的重合分辨时间 (CRT) 进行分析。结果：所有 144 个晶体在晶体泛洪图中都得到了很好的分辨。探测器的平均半峰全宽 (FWHM) 能量分辨率为 12.8%+/- 1.5%，FWHM CRT 为 1.14 +/- 0.02 ns。 12 个晶体的平均 FWHM DoI 分辨率为 2.90 +/- 0.15 mm。结论：基于条状 G-APD 阵列的新型 DoT PET 探测器产生 2.9 mm 的 DoT 分辨率以及出色的定时和能量分辨率。其高复用系数减少了电子通道的数量。因此，这种交叉条带方法可以为专用小动物 PET 和 PET/MR' 以及潜在的临床 PET/MRI 系统提供低成本、高性能 PET 探测器。 (C) 2014 年美国医学物理学家协会。
Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MR') system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore.diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOY), high detection sensitivity, compactness, and insensitivity to magnetic fields.Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 x 2 G-APD strip arrays (25 gm cells) were placed perpendicular on each face of a 12 x 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 x 1.55 x 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoT was measured in step sizes of 1.8 mm by a collimated 18F source. The coincident resolved time (CRT) was analyzed at all DoT positions by acquiring the waveform for each event and applying a digital leading edge discriminator.Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8%+/- 1.5% with a FWHM CRT of 1.14 +/- 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 +/- 0.15 mm.Conclusions: The novel DoT PET detector, which is based on strip G-APD arrays, yielded a DoT resolution of 2.9 mm and excellent timing and energy resolution. Its high multiplexing factor reduces the number of electronic channels. Thus, this cross-strip approach enables low-cost, high-performance PET detectors for dedicated small animal PET and PET/MR' and potentially clinical PET/MRI systems. (C) 2014 American Association of Physicists in Medicine.