Modular Scintillation Cameras: A Progress Report
Modular Scintillation Cameras: A Progress Report
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模块化闪烁相机：进展报告
DOI：
10.1117/12.968647
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发表时间：
1988
影响因子：
--
通讯作者：
L. M. Strimbu
中科院分区：
文献类型：
--
作者：
J. Aarsvold;H. Barrett;J. C. Chen;A. Landesman;T. Milster;D. Patton;T. Roney;R. K. Rowe;R. H. Seacat;L. M. Strimbu
模块化闪烁相机是具有相对较小晶面、少量光电倍增管 (PMT) 和独立处理电子器件的伽马相机。我们的原型模块具有 10 厘米见方的晶面、四个 PMT 和数字处理电子器件。通过将数字化 PMT 响应组合映射到事件位置的最佳位置估计，将闪烁事件信息传输到图像。在我们的原型中，使用查找表来执行此映射。为了更有效地编码闪烁事件信息，我们对每个 PMT 信号使用非线性压缩。还介绍了对数匹配滤波和似然加窗，这是利用光峰值事件分布的泊松模型产生的两种处理技术。对数匹配滤波是一种获得平均检测器响应函数估计的方法，其精度比 PMT 响应的数字化所指示的精度更高。似然窗口是利用似然阈值，而不是熟悉的能量窗口，作为光峰和散射事件的判别式。我们已经在我们的原型模块上实现了上述每一项。该模块的性能特征包括 140 keV 下 10% 半峰全宽 (FWHM) 的能量分辨率以及 90% 晶体上优于 4mm FWHM 的空间分辨率。
Modular scintillation cameras are gamma cameras with relatively small crystal faces, a small number of photomultiplier tubes (PMTs), and independent processing electronics. Our prototypical module has a 10 cm square crystal face, four PMTs, and digital processing electronics. Scintillation event information is transferred to images by mapping digitized PMT response combinations to optimal position estimates of event locations. In our prototype, a look-up table is used to perform this mapping. To encode scintillation event information more effectively, we use nonlinear compression of each of the PMT signals. Also introduced are logarithmic matched filtering and likelihood windowing, two processing techniques that result from exploitations of the Poisson model of the distribution of photopeak events. Logarithmic matched filtering is a method of obtaining estimates of mean detector response functions having greater accuracy than that indicated by the digitization of the PMT responses. Likelihood windowing is the utilization of a likelihood threshold, rather than the familiar energy window, as a discriminant of photopeak and scatter events. We have implemented each of the above on our prototypical module. Performance characteristics of this module include energy resolution of 10% full width at half maximum (FWHM) at 140 keV and spatial resolution of better than 4mm FWHM over 90% of the crystal.