SparseCT: Order-of-Magnitude Dose Reduction with Interrupted-Beam Acquisition

 描述(由申请人提供)：X射线计算机断层扫描(CT)的使用迅速增加，这加剧了人们对整体人群的集体辐射暴露的担忧，以及对因慢性病或持续主诉而接受反复成像的患者的潜在风险。这些担忧促使人们极大地关注实用的辐射剂量减少策略。目前的剂量减少方法，如迭代重建或改进的探测器技术，每种方法都只提供比现有技术状态高达30%-40%的中等剂量减少。我们将通过改变目前CT数据采集和图像重建的范例来追求辐射剂量的更大改善：将以与随机出现或“非相干”伪影相关的角度精选模式获取更少数量的X射线投影，然后通过压缩传感(CS)重建算法去除这些伪影。几个小组已经在模拟中显示了CS重建欠采样CT数据的潜力，但在具有挑战性的快速旋转CT门架的物理环境中，尚未证明非相干欠采样的实用方法。在这个项目中，我们将开发和评估用于快速和非相干中断CT机架上的X射线源的新方法，当与我们的基于稀疏性的CS重建算法相结合时，将能够从显著减少的投影数重建高质量的图像。特别是，我们将研究一种新的移动多孔准直器设计，它将阻止以不同机架角度指向不同探测器子集的X射线。我们已经在模体和人体受试者的初步模拟中证明了这些方法能够按数量级减少剂量，但为了在实际实践中评估我们的方法，我们将与西门子医疗解决方案公司密切合作，后者将在其位于Forchheim的CT工厂专门设立一个实验测试台，开发实用的测试系统，作为功能性临床扫描仪原型的前奏。这项研究的目标的成功完成将为改变CT数据采集和重建模式的方法奠定基础，使迄今为止无法获得的剂量减少成为可能。具体目标如下：1.使用精心设计的真实模拟来验证非相干中断束捕获和稀疏重建的剂量减少潜力，以结合改进的捕获过程的物理原理。2.使用临床扫描数据的回溯性欠抽样(使用Aim 1中的模型)评估在保持图像质量的情况下可实现的剂量减少，并与金标准剂量减少方法进行比较。3.与业界合作伙伴合作开发中断波束CT采集测试系统，并在体模中进行性能评估。

 DESCRIPTION (provided by applicant): Rapidly increasing utilization of X-ray computed tomography (CT) has heightened concerns about the collective radiation exposure to the population as a whole, and about potential risks to patients undergoing recurrent imaging for chronic conditions or persistent complaints. These concerns have motivated a great deal of attention to practical radiation-dose-reduction strategies. Current dose reduction approaches, such as iterative reconstruction or improved detector technology, each offer only moderate dose reductions up to 30- 40% below the prior state of the art. We will pursue more-than-incremental improvements in radiation dose by changing the current paradigm of CT data acquisition and image reconstruction: a reduced number of X-ray projections will be acquired, in an angularly subselected pattern associated with random-appearing or "incoherent" artifacts which will then be removed by compressed-sensing (CS) reconstruction algorithms. Several groups have shown the potential of CS to reconstruct undersampled CT data in simulations, but no practical means of incoherent undersampling has yet been demonstrated in the challenging physical environment of a rapidly rotating CT gantry. In this project, we will develop and evaluate novel approaches for rapid and incoherent interruption of the X-ray source on the CT gantry which, when combined with our sparsity-based CS reconstruction algorithms, will enable reconstruction of high-quality images from a markedly reduced number of projections. In particular, we will investigate a novel moving multihole collimator design which will block X-rays directed towards different subsets of detectors at different gantry angles. We have already shown these approaches to be capable of order-of-magnitude dose reductions in preliminary simulations in both phantoms and human subjects, but in order to evaluate our methods in actual practice, we will work closely with Siemens Medical Solutions, who will dedicate an experimental test bay at their CT plant in Forchheim to develop a practical test system as a prelude to functional clinical scanner prototypes. Successful completion of the aims of this study will lay the groundwork for a paradigm-changing approach to CT data acquisition and reconstruction, enabling heretofore inaccessible dose reductions. Specific Aims are as follows: 1. Validate the dose-reduction potential of incoherent interrupted-beam acquisition and sparse reconstruction using realistic simulations carefully designed to incorporate the physics of the modified acquisition process. 2. Evaluate achievable dose reduction with preserved image quality using retrospective undersampling of clinical scan data (using the model from Aim 1), and compare with gold-standard dose reduction methods. 3. Develop a test system for interrupted-beam CT acquisition in collaboration with our industry partner, and evaluate performance in phantoms.