Stentz Dale J, Sankar Poopalasingam, Johnson Lindsay C, Metzler Scott D
Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 USA.
IEEE Trans Radiat Plasma Med Sci. 2025 May;9(5):531-541. doi: 10.1109/trpms.2024.3517421. Epub 2024 Dec 13.
An array of photomultiplier tubes (PMTs) provides energy readout for gamma cameras, leading to event selection and positioning. However, operational and environmental changes, such as temperature, can cause PMTs to "drift" away from their nominal energy readouts and, therefore, require a correction procedure to return to their reference energies. We present two methods for determining the energy-scale change of each PMT using data collected on C-SPECT, a dedicated cardiac single photon emission computational tomography (SPECT) scanner. A scan of a vertical line source of Tc provides the data from which we produce an energy histogram for each of the 130 PMTs. Each energy histogram is composed of events passing an energy-fraction selection to give events closest to the PMT center. We consider energy fractions ranging from 0.25% to 5.00%. For our analysis, we use bootstrapping to create data realizations as well as emulating energy-scale changes (simultaneously and independently for all PMTs) in the data. Using the average relative error as a measurement of the accuracy and the standard deviation from taking bootstrapped replicates of our data as a measurement of our precision, we determine the energy-scaling to within -0.05% ± 0.03% (mean and standard deviation, respectively).
一组光电倍增管（PMT）为伽马相机提供能量读数，从而实现事件选择和定位。然而，诸如温度等操作和环境变化会导致光电倍增管偏离其标称能量读数，因此需要一个校正程序使其回到参考能量。我们提出了两种方法，利用在专用心脏单光子发射计算机断层扫描（SPECT）扫描仪C-SPECT上收集的数据来确定每个光电倍增管的能量刻度变化。对锝的垂直线源进行扫描可提供数据，据此我们为130个光电倍增管中的每一个生成能量直方图。每个能量直方图由通过能量分数选择的事件组成，以给出最接近光电倍增管中心的事件。我们考虑的能量分数范围为0.25%至5.00%。在我们的分析中，我们使用自助法来创建数据实现，并在数据中模拟能量刻度变化（对所有光电倍增管同时且独立地进行）。使用平均相对误差作为准确性的度量，以及通过对我们的数据进行自助重复抽样得到的标准偏差作为精度的度量，我们确定能量刻度在-0.05%±0.03%（分别为均值和标准偏差）以内。
