Depth of interaction calibration for PET detectors with dual-ended readout by PSAPDs.
Depth of interaction calibration for PET detectors with dual-ended readout by PSAPDs.
复制标题
PSAPD的双端读数的PET探测器的相互作用校准深度。
DOI：
10.1088/0031-9155/54/2/017
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发表时间：
2009-01-21
影响因子：
3.5
通讯作者：
Cherry SR
中科院分区：
文献类型：
--
作者：
Yang Y;Qi J;Wu Y;St James S;Farrell R;Dokhale PA;Shah KS;Cherry SR
许多实验室正在开发深度编码探测器，以改善正电子发射断层扫描(PET)扫描仪的空间分辨率和灵敏度之间的权衡。实现这些探测器的一个挑战是需要校准扫描仪中大量探测器元件的相互作用深度(DOI)响应。在这项工作中，我们评估了两种不同的方法，线性探测器校准和线性晶体校准，以确定DOI校准参数。这两种方法都可以使用来自任何震源分布和位置的测量，甚至可以使用LSO固有的背景活动，因此非常适合用于深度编码PET扫描仪。通过在一台原型深度编码PET扫描仪中测量所有八个探测器的探测器和晶体DOI响应来评估这些方法。探测器采用位置敏感型雪崩光电二极管(PSAPD)双端读出LSO闪烁体阵列。LSO阵列有7×7个单元，晶体尺寸为0.92×0.92×20 mm~3，间距为1.0 mm。阵列由放置在阵列相对两端的两个8×8mm2面积的PSAPD读出。DOI由两个PSAPD测量的总能量信号的幅度之比来测量。观察到阵列内不同晶体的DOI响应以及不同阵列的DOI响应的微小差异。观察到DOI比对深度的轻微非线性依赖关系，角晶体和边缘晶体的非线性较大。从单次模式下测得的DOI响应中获取DOI定标参数。如果使用线性探测器DOI校准，则校准后的DOI与已知DOI之间的平均误差为0.8 mm；如果使用线性晶体DOI校准，则校准后的DOI与已知DOI之间的平均误差为0.5 mm。在PET扫描仪上对线源体模和热棒体模进行了扫描。无论采用哪种DOI定标方法，DOI测量都能显著提高图像的空间分辨率。与线性探测器DOI校准相比，线性晶体DOI校准提供了略好的图像空间分辨率。
Many laboratories are developing depth-encoding detectors to improve the trade-off between spatial resolution and sensitivity in positron emission tomography (PET) scanners. One challenge in implementing these detectors is the need to calibrate the depth of interaction (DOI) response for the large numbers of detector elements in a scanner. In this work, we evaluate two different methods, a linear detector calibration and a linear crystal calibration, for determining DOI calibration parameters. Both methods can use measurements from any source distribution and location, or even the intrinsic LSO background activity, and are therefore well-suited for use in a depth-encoding PET scanner. The methods were evaluated by measuring detector and crystal DOI responses for all eight detectors in a prototype depth-encoding PET scanner. The detectors utilize dual-ended read out of lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiodes (PSAPDs). The LSO arrays have 7×7 elements, with a crystal size of 0.92×0.92×20 mm3 and pitch of 1.0 mm. The arrays are read out by two 8×8 mm2 area PSAPDs placed at opposite ends of the arrays. DOI is measured by the ratio of the amplitude of the total energy signals measured by the two PSAPDs. Small variations were observed in the DOI responses of different crystals within an array as well as DOI responses for different arrays. A slightly nonlinear dependence of the DOI ratio on depth was observed and the nonlinearity was larger for the corner and edge crystals. The DOI calibration parameters were obtained from the DOI responses measured in singles mode. The average error between the calibrated DOI and the known DOI was 0.8 mm if a linear detector DOI calibration was used, and 0.5 mm if a linear crystal DOI calibration was used. A line source phantom and a hot rod phantom were scanned on the prototype PET scanner. DOI measurement significantly improved the image spatial resolution no matter which DOI calibration method was used. A linear crystal DOI calibration provided slightly better image spatial resolution compared with a linear detector DOI calibration.
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