Task-driven dynamic beam modulation for high-performance,low-dose CT.

描述（由申请人提供）：正如FOA对亚msv CT的认识，CT利用率的增加和相关人群辐射剂量的增加促使了剂量减少方法的发展。任何有意义的剂量减少策略都必须与图像质量分析相结合。然而，剂量和图像质量之间的关系是复杂的，因为依赖于成像任务和患者的特定特征。该计划通过硬件修改来开发任务驱动型CT，允许为患者定制CT采集，并通过基于任务的性能预测框架来驱动特定成像场景的最佳剂量利用率。具体而言，将基于多孔径器件（MADs）开发一种新型的轻型紧凑x射线束调制器，该调制器具有高动态范围调制能力，适合典型的CT龙门旋转速率。这种方法允许对x射线束的空间剖面进行高度控制，包括到达探测器的通量剖面的平坦化和感兴趣区域（ROI）扫描。这些设备的驱动将由基于3D侦察体积的图像质量计划和基于任务的可检测性框架驱动，该框架包括测量物理的复杂模型、成像任务定义、人类视觉系统和应用于数据的特定重建方法。虽然动态波束调制单独产生显著的剂量减少，但通过使用为波束调制获取定制的先进统计重建算法，这些优势将与额外的减少协同作用。我们假设，为患者的特定成像需求量身定制的任务驱动型诊断CT扫描仪将提供足够大的剂量降低，从而使许多身体CT扫描场景可以被驱动到低于msv的水平，这是本计划公告的目标。研究任务驱动型CT的具体目标如下：1)开发集成到诊断型CT扫描仪中的动态波束调制硬件。设计，表征，并将MAD调制器集成到CT采集系统中。2)创建动态调制CT采集的重构框架。对波束调制数据采用传统和统计重构算法。3)开发动态调制CT的性能预测框架。将开发一个复杂的物理模型和基于任务的数学观测器，以预测移位变量、患者特异性和获取依赖的图像质量。4)制定驱动基于患者和任务的光束调制的策略。使用图像质量计划（包括可能的移位变量规格，例如ROI成像）和预测框架前瞻性地设计剂量限制内的最佳光束调制。5)评估患者和特定任务的束调制CT。评估结果措施将包括定量成像性能指标，吸收剂量测量和基于蒙特卡罗估计的剂量图，以及使用尸体研究的观察者偏好测试，包括与最小剂量方案的关系。

DESCRIPTION (provided by applicant): As recognized in the FOA for sub-mSv CT, the increased CT utilization and the associated increase in population radiation dose motivates the development of dose reduction methods. Any meaningful strategies for dose reduction must be coupled with an analysis of image quality. However, the relationship between dose and image quality is complex due to dependencies on the imaging task and patient-specific characteristics. The pro- posed effort develops task-driven CT through hardware modifications that permit customizing the CT acquisition to the patient, and through a task-based performance prediction framework that is used to drive optimal dose utilization for specific imaging scenarios. Specifically, a novel lightweight and compact x-ray beam modulator capable of high dynamic range modulations and suitable for typical CT gantry rotation rates will be developed based on multiple aperture devices (MADs). This approach allows for a high degree of control over the spatial profile of the x-ray beam including flattening of fluence profile arriving at the detector nd region-of- interest (ROI) scanning. Actuation of these devices will be driven by an image quality plan based on a 3D scout volume and a task-based detectability framework that includes sophisticated models of the measurement physics, imaging task definitions, the human visual system, and the particular reconstruction approaches applied to the data. While dynamic beam modulation alone yields significant dose reductions, these advantages will be synergized with additional reductions through the use of advanced statistical reconstruction algorithms customized for beam modulated acquisitions. We hypothesize that a task-driven diagnostic CT scanner tailored to the specific imaging needs of the patient will provide large enough dose reductions that many body CT scanning scenarios can be driven to sub-mSv levels as targeted by this program announcement. The following Specific Aims are proposed to develop and investigate task-driven CT: 1) Develop dynamic beam modulation hardware for integration into diagnostic CT scanners. Design, characterize, and integrate the MAD modulators into CT acquisition systems. 2) Create a reconstruction framework for dynamically modulated CT acquisitions. Adapt both traditional and statistical reconstruction algorithms to beam modulated data. 3) Develop a performance prediction framework for dynamically modulated CT. A sophisticated physical model and task-based mathematical observer will be developed that predicts the shift-variant, patient-specific, and acquisition-dependent image quality. 4) Develop strategies for driving patient- and task-based beam modulations. Using image quality plans (including possibly shift-variant specification, e.g. ROI imaging) and the prediction framework prospectively design optimal beam modulations within dose constraints. 5) Assess patient- and task-specific beam-modulated CT. Evaluation outcome measures will include quantitative imaging performance metrics, absorbed dose measurements and dose maps based on Monte Carlo estimation, and an observer preference test using cadaver studies including relations to minimum dose protocols.