Correction of count losses due to deadtime on a DST-XLi (SMVi-GE) camera during dosimetric studies in patients injected with iodine-131
Correction of count losses due to deadtime on a DST-XLi (SMVi-GE) camera during dosimetric studies in patients injected with iodine-131
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DOI：
10.1088/0031-9155/47/7/402
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发表时间：
2002-04-07
影响因子：
3.5
通讯作者：
Bardiès, M
中科院分区：
文献类型：
--
作者：
Delpon, G;Ferrer, L;Bardiès, M
在治疗性注射后进行的剂量测定研究中，必须校正由于伽马相机上的死区时间造成的计数损失。本说明描述了四种死区时间校正方法，一种基于使用标准源而不进行初步校准，三种需要特定校准并基于在不同光谱窗口（20%，20%加上较低能量窗口，以及50-750 keV的全光谱）中观察到的计数率。在体模上进行了实验，在越来越高的计数率下检查不同方法的校正精度。使用标准源的误差小于+7%，而基于计数率的方法给出了更准确的结果。假设该模型是可瘫痪的，初步校准允许将观察到的计数率曲线绘制为真实的计数率的函数。使用全光谱导致对成像的最高活性低估3.0%。由于计数损失取决于与能量无关的光子通量，因此在测量期间使用全光谱允许考虑散射条件。开发了一个协议，将这种校正方法应用于全身采集。
In dosimetric studies performed after therapeutic injection, it is essential to correct count losses due to deadtime on the gamma camera. This note describes four deadtime correction methods, one based on the use of a standard source without preliminary calibration, and three requiring specific calibration and based on the count rate observed in different spectrometric windows (20%, 20% plus a lower energy window, and the full spectrum of 50-750 keV). Experiments were conducted on a phantom at increasingly higher count rates to check correction accuracy with the different methods.The error was less than +7% with a standard source, whereas count-rate-based methods gave more accurate results. On the assumption that the model was paralysable, preliminary,, calibration allowed an observed count rate curve to be plotted as a function of the real count rate. The use of the full spectrum led to a 3.0% underestimation for the highest activity imaged. As count losses depend on photon flux independent of energy,the use of the full spectrum during measurement allowed scatter conditions to be taken into account. A protocol was developed to apply this correction method to whole-body acquisitions.