Enabling Ultra Low Dose PET/CT Imaging

描述(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)扫描仪对癌症进行成像已成为肿瘤学诊断和分期的标准组成部分。此外，定量PET/CT对于评估个体对治疗的反应和新的癌症疗法的临床试验是一个有价值的工具。然而，肺部和腹部的PET/CT成像通常受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，以及导致衰减校正误差、配准误差和肿瘤误定位的PET和CT图像不匹配。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。第二个误差源(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，对于诊断成像程序来说，辐射剂量也高得令人无法接受。我们的目标是大幅减少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。这将通过补偿呼吸运动引起的伪影来实现更准确的PET/CT成像。这一目标是可行的，因为对PET/CT成像的CT分量的要求不同于诊断性CT。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，(2)在PET/CT成像中提供常规和高质量的呼吸运动伪影补偿。这将提高定量PET/CT成像的能力，用于开发急需的癌症治疗方法，评估单个患者的治疗反应，并在注意到病变吸收的情况下进行临床报告。呼吸运动检测是诊断和分期的主要工具，其影响尚不清楚，但也尚未得到适当的评估。此外，本文开发的超低剂量CT方法还可用于其他应用，如肺部CT成像、动态增强CT或新的示踪剂、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.