Characterization and correction of pulse pile-up in simultaneous emission-transmission computed tomography.
Characterization and correction of pulse pile-up in simultaneous emission-transmission computed tomography.
复制标题
同时发射传输计算机断层扫描中脉冲堆积的表征和校正。
DOI：
10.1118/1.597692
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发表时间：
1996
期刊：
影响因子：
3.8
通讯作者：
Hasegawa,BH
中科院分区：
文献类型：
--
作者：
Wu,X;Brown,JK;Kalki,K;Hasegawa,BH
我们开发了一种发射-透射式CT(ETCT)系统，使用普通的光子计数探测器，既可以进行单光子发射计算机层析成像(SPECT)，也可以进行X射线透射式CT成像。原则上，使用ETCT系统可以同时采集SPECT和X射线CT投影数据；但是，这样做会导致SPECT投影数据受到污染，因为相对较高的X射线注量率会造成脉冲堆积。在这项研究中，我们通过计算机模拟和实验研究来表征脉冲堆积对同时ETCT成像的影响。我们证明，对于足够小的X射线注量率，SPECT能量窗内的脉冲堆积可以用堆积率和X射线注量率之间的简单的二次关系来很好地近似。利用这种二次关系，我们开发了一种简单的堆积校正方案，该方案从排放数据中减去堆积计数，并截断排放预测数据的外部区域。对不同图像和轮廓的分析表明，这种方法允许我们重建SPECT图像，与通过顺序发射和传输扫描获得的图像相比，没有明显的噪声或分辨率下降。
We have developed an emission–transmission CT (ETCT) system capable of both single‐photon emission computed tomography (SPECT) imaging and x‐ray transmission CT imaging using a common photon counting detector. In principle, SPECT and x‐ray CT projection data can be acquired simultaneously with the ETCT system; however, doing so results in contamination of the SPECT projection data due to pulse pile‐up caused by the relatively high x‐ray fluence rate. In this study, we characterize the effects of pulse pile‐up for simultaneous ETCT imaging through computer simulation and experimental studies. We demonstrate that pulse pile‐up in the SPECT energy window can be well approximated by a simple quadratic relationship between the pile‐up rate and the x‐ray fluence rate for sufficiently small x‐ray fluence rates. Using this quadratic relationship, we developed a simple pile‐up correction scheme that subtracts the pile‐up counts from the emission data and also truncates the exterior regions of the emission projection data. Analysis of difference images and profiles indicate that this method permits us to reconstruct SPECT images with no apparent noise or resolution degradation in comparison to those obtained via sequential emission and transmission scans.