Dead time correction and counting statistics for positron tomography.
Dead time correction and counting statistics for positron tomography.
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DOI：
10.1088/0031-9155/30/5/002
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发表时间：
1985-05
影响因子：
3.5
通讯作者：
B. Mazoyer;M. Roos;R. Huesman
中科院分区：
文献类型：
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作者：
B. Mazoyer;M. Roos;R. Huesman
对动态正电子发射断层扫描（PET）中由于死区时间造成的事件损失进行了修正。该模型采用瘫痪死区时间来描述层析成像在患者研究中通常遇到的事件率范围内的行为（每个检测器层高达20万事件/秒）。Donner 280晶体正电子层析成像的死区时间为1.8微秒/事件，观察到的计数率小于200000事件/秒。在18万事件/秒时，死区时间校正系数为1.8。将校正应用于动态PET研究的投影数据和兴趣区域分析，并建立了同一动态研究中不同图像中校正后的投影数据与兴趣区域计数之间的协方差公式。在18万事件/秒时，在包含3.34 X 10(5)个实际事件的区域中，实际（修正）事件数的方差从模型中预测为3.86 X 10(6)（事件）2，是从泊松统计的朴素假设中期望的方差的10倍以上。这些统计结果得到了实验验证。如果不应用死区时间补偿，在心肌流量中观察到25%的误差，表明这种校正的必要性。
A correction for loss of events due to dead time in dynamic positron emission tomography (PET) is presented. The model employs a paralysing dead time to describe the behaviour of a tomograph over the range of event rates normally encountered in patient studies (up to 200 000 events/s per detector layer). The Donner 280-crystal positron tomograph has a dead time of 1.8 microseconds/event for observed count rates less than 200 000 events/s. The dead time correction factor is 1.8 at 180 000 events/s. The correction is applied to projection data and region of interest analysis of dynamic PET studies, and formulae for the covariances between corrected projection data and between counts in regions of interest in different images from the same dynamic study are established. At 180 000 events/s, the variance of the actual (corrected) number of events in a region containing 3.34 X 10(5) actual events is predicted from the model to be 3.86 X 10(6) (events)2, more than 10 times the variance that would be expected from a naive assumption of Poisson statistics. These statistical results are verified experimentally. An error of 25% is observed in myocardial flow if dead time compensation is not applied, showing the necessity for this correction.