Energy-based image reconstruction for new generation PET

描述（由申请人提供）：本项目是一项长期努力的一部分，旨在提高正电子发射断层扫描（PET）获得的图像质量，PET已成为诊断放射学和核医学中重要的断层成像技术。该项目涉及从PET扫描仪的基本探测器数据生成图像的计算机方法，包括补偿数据的非理想特征的处理操作，以及从初始处理产生的投影数据重建图像的算法。使用现有的PET扫描仪和数据处理方法，我们发现，与正常大小的患者相比，大型患者的PET扫描数据集包含更大比例的散射光子和更小比例的未散射光子，因此获得的图像质量远低于正常大小的患者。该项目的目的是通过使用新的方法来处理数据，利用未散射和散射光子的能量分布之间的显著差异，从而改善PET中获得的图像。新的基于能量的方法将利用现代扫描仪更好的能量分辨率，并将充分利用下一代闪烁晶体和探测器的优异能量分辨率和时间。所提出的方法具有通用性，可以比目前使用的基于图像的散射估计方法更简单地应用于当前的常规PET扫描仪。它们的设计还将满足新一代飞行时间PET （TOF-PET）扫描仪的需要，目前尚未开发出适当的散射校正技术。该方法旨在开发、实施、测试和评估基于能量的PET和TOF-PET新方法的可行性，包括结合图像重建和散点估计。这些方法将与最广泛使用的传统方法，即单散射模拟方法的扩展进行比较。比较研究将使用模拟数据和物理测试模型的实验PET数据进行。基于能量的新方法有可能显著提高PET图像中逐体素估计放射性示踪剂吸收的准确性，这将改善PET的临床应用，例如PET对癌症的成像，这反过来将对公众健康产生重大影响。

DESCRIPTION (provided by applicant): This project is part of a long-term effort to improve the quality of the images obtained by positron emission tomography (PET), which has become an important technique for tomographic imaging in diagnostic radiology and nuclear medicine. The project involves computer methods for generating images from the basic detector data of PET scanners, including processing operations to compensate for non-ideal characteristics of the data, and algorithms for image reconstruction from the projection data produced by the initial processing. With the present PET scanners and methods for processing the data, it is found that the images obtained for large patients are of much lower quality than the images for normal-sized patients, because the data set from a PET scan of a large patient contains a larger proportion of scattered photons and a smaller proportion of unscattered photons, compared to the data from a normal-sized patient. The aim of this project is to improve the images obtained in PET through the use of new methods of processing the data that exploit the marked difference between the energy distributions of unscattered and scattered photons. The new energy-based methods will take advantage of the better energy resolution of modern scanners and will enable full use of the excellent energy resolution and timing of the next generation of scintillation crystals and detectors. The methods proposed are general and can be applied to the current conventional PET scanners in a simpler manner than the presently used image based scatter estimation methods. They will also be designed for the needs of the new generation of scanners for time-of-flight PET (TOF-PET), for which adequate scatter correction techniques have not yet been developed. The approach is to develop, implement, test, and evaluate for feasibility, new energy-based methods for PET and TOF-PET involving combined image reconstruction and scatter estimation. These methods will be compared with extensions of the most widely used conventional method, which is the single-scatter- simulation method. The comparison studies will be done using simulated data and using experimental PET data from physical test phantoms. New energy-based methods have the potential to significantly improve the accuracy of the voxel-by-voxel estimates of radiotracer uptake in PET images, which would lead to improvements in the clinical applications of PET, such as PET imaging of cancer, which would in turn have a significant impact on public health.