Enabling Ultra Low Dose PET/CT Imaging

描述（由申请人提供）：使用正电子发射断层扫描/计算机断层扫描（PET/CT）扫描仪进行癌症成像已成为肿瘤诊断和分期的标准组成部分。此外，定量PET/CT是评估个体对治疗的反应和新型癌症治疗的临床试验的有价值的工具。然而，肺和腹部的PET/CT成像通常受到患者呼吸运动的影响，这可能导致低估感兴趣区域内的示踪剂浓度、高估肿瘤体积以及产生衰减校正误差、配准误差和肿瘤错误定位的不匹配的PET和CT图像。第一个误差源（衰减失配）可以通过使用与呼吸门控PET扫描相位匹配的呼吸门控CT图像执行基于CT的衰减校正来解决。第二误差源（运动模糊）可以通过使用呼吸运动估计和/或门控的方法来解决。问题是，即使使用尽可能低的CT技术，辐射剂量对于诊断成像程序也是不可接受的高。我们的目标是显着降低CT辐射剂量，同时通过减少呼吸运动引入的误差来改善PET图像。这将通过实现呼吸运动引起的伪影的补偿来实现更准确的PET/CT成像。这一目标是可行的，因为PET/CT成像的CT组件要求与诊断CT不同。本文提出的方法将（1）减少基于CT的衰减校正方法的辐射剂量，以及（2）提供PET/CT成像中呼吸运动伪影的常规和高质量补偿。这将提高定量PET/CT成像在开发急需的癌症治疗、评价个体患者对治疗的反应以及在临床报告中记录病变摄取的能力。作为诊断和分期的主要工具，呼吸运动对检测的影响尚不清楚，但也尚未得到适当的评价。此外，本文开发的超低剂量CT方法可用于其他应用，例如肺部CT成像、使用对比剂或新示踪剂的动态CT、PET/CT引导的放射治疗计划和PET/CT心脏成像。

DESCRIPTION (provided by applicant): Imaging of cancer with combined positron emission tomography/computed tomography (PET/CT) scanners has become a standard component of oncology diagnosis and staging. Furthermore, quantitative PET/CT is a valuable tool for assessment of an individual's response to therapy and for clinical trials of novel cancer therapies. PET/CT imaging of the lung and abdomen, however, is generally affected by patient respiratory motion, which can lead to underestimation of tracer concentration within a region of interest, overestimation of tumor volume, and mis-matched PET and CT images that yield attenuation correction errors, registration errors and tumor mis-localization. The first source of error (attenuation mismatch) can be addressed by performing CT-based attenuation correction using respiratory gated CT images that are phase-matched with the respiratory gated PET scans. The second source of error (motion blurring) can be addressed by methods using respiratory motion estimation and/or gating. The problem is that even with the lowest possible CT technique, the radiation dose is unacceptably high for diagnostic imaging procedures. Our goal is to reduce CT radiation dose dramatically, while improving PET image by reducing errors introduced by respiratory motion. This will enable more accurate PET/CT imaging by enabling compensation of respiratory motion induced artifacts. This is goal is feasible due to the requirements for the CT component of PET/CT imaging, which are different than those for diagnostic CT. The methods proposed here will (1) reduce radiation dose from CT-based attenuation correction methods and (2) provide routine and high quality compensation of respiratory motion artifacts in PET/CT imaging. This will improve the capabilities of quantitative PET/CT imaging in the development of badly needed therapies for cancer, in the evaluation of response to therapy by for an individual patient, and where lesion uptake is noted is a clinical report. The impact of respiratory motion for detection, a primary tool in diagnosis and staging is not clear, but has also not been properly evaluated yet. In addition, the ultra low dose CT methods developed here may be useful for other applications, such as pulmonary CT imaging, dynamic CT with contrast or new tracers, PET/CT guided radiation treatment planning, and PET/CT cardiac imaging.