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，这加剧了对整个人群集体辐射暴露的担忧，以及对因慢性疾病或持续性投诉接受复发性成像的患者的潜在风险。这些关切促使人们高度重视减少辐射剂量的实际战略。目前的剂量减少方法，如迭代重建或改进的探测器技术，每种方法都只能提供比现有技术水平低30- 40%的中等剂量减少。我们将通过改变当前的CT数据采集和图像重建模式来追求辐射剂量的增量改进：将以与随机出现或“不相干”伪影相关的角度子选择图案采集减少数量的X射线投影，然后将通过压缩感测（CS）重建算法去除所述伪影。几个小组已经显示了CS在模拟中重建欠采样CT数据的潜力，但是在快速旋转CT机架的具有挑战性的物理环境中还没有证明不相干欠采样的实用方法。 在这个项目中，我们将开发和评估新的方法，快速和不相干中断的X射线源的CT机架，当结合我们的稀疏性为基础的CS重建算法，将使高质量的图像重建从一个显着减少的投影数量。特别是，我们将研究一种新的移动多孔准直器的设计，这将阻止X射线在不同的机架角度指向不同的探测器子集。 我们已经证明了这些方法能够在幻影和人类受试者的初步模拟中减少数量级的剂量，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密切合作，他们将在Forchheim的CT工厂专门建立一个实验测试台，以开发一个实用的测试系统，作为功能性临床扫描仪原型的前奏。成功完成这项研究的目的将奠定基础的一个范式改变的方法，CT数据采集和重建，使迄今无法达到的剂量减少。具体目标如下：1.使用经过精心设计的真实模拟来验证非相干中断束采集和稀疏重建的剂量降低潜力，以纳入修改后的采集过程的物理特性。2.使用临床扫描数据的回顾性欠采样（使用目标1中的模型）评价在保留图像质量的情况下可实现的剂量降低，并与金标准剂量降低方法进行比较。3.与我们的行业合作伙伴合作开发用于中断束CT采集的测试系统，并评估体模性能。

 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.