Sub-3 mm, near-200 ps TOF/DOI-PET imaging with monolithic scintillator detectors in a 70 cm diameter tomographic setup
Sub-3 mm, near-200 ps TOF/DOI-PET imaging with monolithic scintillator detectors in a 70 cm diameter tomographic setup
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DOI：
10.1088/1361-6560/aad2a6
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发表时间：
2018-08-01
影响因子：
3.5
通讯作者：
Schaart, Dennis R.
中科院分区：
文献类型：
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作者：
Borghi, Giacomo;Tabacchini, Valerio;Schaart, Dennis R.
最近，开发了用于飞行时间（TOF）/相互作用深度（DOI）正电子发射断层扫描（PET）的单片闪烁体探测器。它具有类似于1.7 mm半高全宽（FWHM）的探测器空间分辨率，类似于215 ps FWHM的符合分辨时间（CRT），以及类似于4.7 mm FWHM DOI分辨率。在这里，我们展示了，第一次，这个探测器在70厘米直径的PET几何成像性能。我们建立了一个全身临床扫描仪，包括两个同轴旋转臂，每个携带一个探测器模块，和一个中央，旋转体模台的断层设置代表。全自动设置使用步进拍摄采集方法顺序采集完整探测器环的所有可能的响应线（LOR）。这些模块包含2 × 2个检测器，每个检测器由32 mm × 32 mm × 22 mm LYSO晶体和数字硅光电倍增管（dSiPM）阵列组成。使用Na-22点源在视场（FOV）中的不同径向距离处评估系统的空间分辨率。使用2D滤波反投影（2D FBP，非TOF），在FOV中心获得了类似于2.9 mm FWHM的切向和径向空间分辨率。DOI信息的使用导致直到25 cm的径向距离的整个FOV的几乎均匀的空间分辨率，其中径向和切向分辨率分别类似于3.3 mm FWHM和类似于4.7 mm FWHM，而没有DOI，分辨率恶化到类似于9 mm FWHM。使用Na-22填充的Derenzo样体模在FOV内的不同位置进行额外测量。用TOF最大似然期望最大化（TOF ML-EM）算法重建的图像表明，该系统能够清晰地分辨直径为3 mm的热棒，径向距离可达25 cm。其优异的均匀空间分辨率、10.2%FWHM的能量分辨率和接近212 ps FWHM的CRT显示器显示了单片放大器作为TOF/DOI-PET系统中实用的高性能探测器的巨大潜力。
Recently, a monolithic scintillator detector for time-of-flight (TOF)/depth-of-interaction (DOI) positron emission tomography (PET) was developed. It has a detector spatial resolution of similar to 1.7 mm full-width-at-half-maximum (FWHM), a coincidence resolving time (CRT) of similar to 215 ps FWHM, and similar to 4.7 mm FWHM DOI resolution. Here, we demonstrate, for the first time, the imaging performance of this detector in a 70 cm diameter PET geometry. We built a tomographic setup representative of a whole-body clinical scanner, comprising two coaxially rotating arms, each carrying a detector module, and a central, rotating phantom table. The fully automated setup sequentially acquires all possible lines of response (LORs) of a complete detector ring, using a stepand-shoot acquisition approach. The modules contained 2 x 2 detectors, each detector consisting of a 32 mm x 32 mm x 22 mm LYSO crystal and a digital silicon photomultiplier (dSiPM) array. The system spatial resolution was assessed using a Na-22 point source at different radial distances in the field-of-view (FOV). Using 2D filtered back projection (2D FBP, non-TOF), tangential and radial spatial resolutions of similar to 2.9 mm FWHM were obtained at the center of the FOV. The use of DOI information resulted in almost uniform spatial resolution throughout the FOV up to a radial distance of 25 cm, where the radial and tangential resolution are similar to 3.3 mm FWHM and similar to 4.7 mm FWHM, respectively, whereas without DOI the resolution deteriorates to similar to 9 mm FWHM. Additional measurements were performed with a Na-22 filled Derenzo-like phantom at different locations within the FOV. Images reconstructed with a TOF maximum-likelihood expectation-maximization (TOF ML-EM) algorithm show that the system is able to clearly resolve 3 mm diameter hot rods up to 25 cm radial distance. The excellent and uniform spatial resolution, combined with an energy resolution of 10.2% FWHM and a CRT of similar to 212 ps FWHM, indicates a great potential for monolithic scintillators as practical high-performance detectors in TOF/DOI-PET systems.