Sensitivity estimation in time-of-flight list-mode positron emission tomography.

PURPOSE An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time-of-flight (TOF) list-mode PET data, which allows performing either or both, a self-attenuation correction, and self-normalization correction based on emission data only. METHODS The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list-mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated. RESULTS The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list-mode TOF-PET data. CONCLUSIONS A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list-mode data.

目的 正电子发射断层扫描（PET）中图像的准确定量需要了解每个体素的实际灵敏度，该灵敏度表示在该体素中发射的正电子最终作为PET扫描仪中一对探测器中的两个伽马射线符合事件被检测到的概率。这种灵敏度取决于采集的特性，因为它受到体内湮灭伽马射线衰减以及扫描仪探测器灵敏度可能变化的影响。在这项工作中，作者提出了一种处理飞行时间（TOF）列表模式PET数据的新方法，该方法允许仅基于发射数据进行自衰减校正和自归一化校正中的一项或两项。 方法 作者使用完整数据的完全贝叶斯统计模型推导出理论。作者使用具有不同TOF分辨率和检测到的符合事件总数的二维数值列表模式模拟，对从该理论推导并在本工作中提出的算法进行了初步评估。未模拟随机事件和散射的影响。 结果 作者发现，对于模拟的二维列表模式TOF - PET数据，所提出的算法成功地校正了未知衰减和扫描仪归一化。 结论 提出了一种可用于使用TOF列表模式数据进行衰减和归一化（灵敏度）校正的新方法。