Study on the stability of the calibration and normalization in PET and the influence of drifts on the accuracy of quantification
Study on the stability of the calibration and normalization in PET and the influence of drifts on the accuracy of quantification
复制标题
PET校准和归一化的稳定性以及漂移对定量准确度的影响研究
DOI：
10.1007/bf00631766
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Werner Kleeb
中科院分区：
文献类型：
--
作者：
H. Reist;O. Stadelmann;Werner Kleeb
对正电子发射层析成像定量的质量控制进行了研究，以建立一种简便的方法进行频繁监测。通过绘制非归一化计数率的均方根偏差和归一化计数率的标准差，分别归一化到校准或归一化后的值，来检验检测器计数率的稳定性和均匀性。关闭单个检测器不会影响图像质量，但当关闭检测器块时，归一化图像像素计数减少2%-3%。因此，在需要的情况下，仍然可以使用弱检测器来执行扫描。与一年前获得的最大可用活性8x104Bq/ml相比，在特定活性高于5x104Bq/ml（校正后的系统真计数/s或飞机上的1.5x104/s）的计数率能力降低，这表明计数损失校正存在漂移。室温的变化使龙门架内部的温度分布每°C变化5%，灵敏度（归一化图像像素计数）的漂移为每°C 2%。
With regard to the quality control of quantification in positron emission tomography some characteristics were examined, to develop a simple method for frequent monitoring. The stability and uniformity of the detector count rate was checked by plotting the RMS deviation of the non normalized count rate and the standard deviation of the normalized count rate, each normalized to its value after the calibration or normalization respectively. Switching off a single detector did not impair the image quality, but the normalized image pixel counts were reduced by 2%–3% when a detector block was switched off. Thus in case of need, a weak detector can still be used to perform a scan. A reduced count rate capability at specific activities above 5x104Bq/ml (∼1.5x105corrected true system counts/s or ∼1.5x104/s for a plane) was found compared to the maximum usable activity of 8x104Bq/ml obtained 1 year earlier, indicating a drift in the count loss corrections. A variation of the room temperature changes the temperature distribution inside the gantry by 5% per °C and the drift of the sensitivity (normalized image pixel counts) is 2% per °C.