Use of internal scintillator radioactivity to calibrate DOI function of a PET detector with a dual-ended-scintillator readout
Use of internal scintillator radioactivity to calibrate DOI function of a PET detector with a dual-ended-scintillator readout
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DOI：
10.1118/1.3676688
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发表时间：
2012-02-01
期刊：
影响因子：
3.8
通讯作者：
Shao, Yiping
中科院分区：
文献类型：
--
作者：
Bircher, Chad;Shao, Yiping
目的：使用双端闪烁体读出来测量相互作用深度（DOI）的正电子发射断层摄影（PET）探测器必须具有精确的DOI函数，以提供DOI与信号比之间的关系，以用于探测器校准和重新校准。在先前的研究中，作者使用了一种新颖而简单的方法，通过用外部均匀泛源照射探测器来准确快速地测量DOI函数;然而，作为一个实际问题，在组装的PET系统中实施外部均匀泛源在技术上具有挑战性且昂贵。因此，在当前的研究中，作者研究了是否可以使用相同的方法从闪烁体生成的（即，内部）辐射。作者还开发了一种用于校准所需的能量window.Methods内选择的事件的能量尺度的方法：作者测量的DOI功能的PET探测器与正硅酸钇镥（LYSO）emulator。辐射事件起源于放射性物质的内部Lu-176 β衰变被用来测量DOI函数，然后将其与从外部均匀泛源和电子准直外部点源测量的DOI函数进行比较。作者用几种不同几何形状的蒸发器进行了这些研究（1.5 x 1.5和2.0 x 2.0 mm（2）横截面积和20、30和40 mm长度）和各种表面处理（镜面抛光、锯切粗糙以及介于两者之间的其他抛光）和原型阵列。结果：所有使用内部和外部辐射源的测量结果显示出良好的协议在DOI功能测量。从内部和外部辐射源测量的所有闪烁器的DOI值之间的平均差异小于1.0 mm的不同闪烁体的几何形状和各种表面finishing.Conclusions：LYSO闪烁器的内部放射性可以用来准确地测量DOI功能PET探测器，无论闪烁体的几何形状或表面光洁度。由于不需要外部辐射源，这种DOI函数测量方法可以实际应用于单个PET探测器以及组装系统。(C)2012年美国医学物理学家协会。[DOI 10.1118/1.3676688]
Purpose: Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous study, the authors used a novel and simple method to accurately and quickly measure DOI function by irradiating the detector with an external uniform flood source; however, as a practical concern, implementing external uniform flood sources in an assembled PET system is technically challenging and expensive. In the current study, therefore, the authors investigated whether the same method could be used to acquire DOI function from scintillator- generated (i.e., internal) radiation. The authors also developed a method for calibrating the energy scale necessary to select the events within the desired energy window.Methods: The authors measured the DOI function of a PET detector with lutetium yttrium orthosilicate (LYSO) scintillators. Radiation events originating from the scintillators' internal Lu-176 beta decay were used to measure DOI functions which were then compared with those measured from both an external uniform flood source and an electronically collimated external point source. The authors conducted these studies with several scintillators of differing geometries (1.5 x 1.5 and 2.0 x 2.0 mm(2) cross-section area and 20, 30, and 40 mm length) and various surface finishes (mirror-finishing, saw-cut rough, and other finishes in between), and in a prototype array.Results: All measured results using internal and external radiation sources showed excellent agreement in DOI function measurement. The mean difference among DOI values for all scintillators measured from internal and external radiation sources was less than 1.0 mm for different scintillator geometries and various surface finishes.Conclusions: The internal radioactivity of LYSO scintillators can be used to accurately measure DOI function in PET detectors, regardless of scintillator geometry or surface finish. Because an external radiation source is not needed, this method of DOI function measurement can be practically applied to individual PET detectors as well as assembled systems. (C) 2012 American Association of Physicists in Medicine. [DOI: 10.1118/1.3676688]