Consistency Conditions for Artifact Reduction in Cone-beam CT

锥束CT伪影减少的一致性条件

基本信息

批准号：
273134754
负责人：
Professor Dr.-Ing. Andreas Maier
金额：
--
依托单位：
Lehrstuhl für Informatik 5: Mustererkennung
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/273134754?language=en
关键词：
Consistency Conditions Artifact Reduction Cone

项目摘要

Tomographic reconstruction is the enabling technology for a wide range of transmission-based 3D imaging modalities, most notably X-ray Computed Tomography (CT). The first CT scanners built in the 70ies used parallel geometries. In order to speed up acquisition, the systems soon moved to fan-beam geometries and a much faster rotation speed. Today´s CT systems rotate four times per second and use a cone-beam geometry. This is fast enough to cover even complex organ motion such as the beating heart. However, there exists a large class of specialized CT systems that are not able to perform such fast scans. Systems using a flat-panel detector, as they are employed in C-arm angiography systems, on-board imaging systems in radiation therapy, or mobile C-arm systems, face mechanical challenges as they were mainly built to perform 2D imaging. About 15 years ago flat-detector scanners have been enabled to acquire three dimensional data. 3D imaging on these systems, however, is challenging due to their slower acquisition speed between five seconds and one minute and a small field-of-view (FOV) with a diameter of 25 to 40 cm. These drawbacks are related to the scanners´ design as highly specialized modalities. In contrast to other disadvantages of flat panel detectors like increased X-ray scattering and limited dynamic range, they will not be remedied by hardware evolution in the foreseeable future, e.g. faster motion is impossible because of the risk of collisions in the operation room. As a result, Flat-Detector Computed Tomography (FDCT) will continue to be more susceptible to artifacts in the reconstructed image due to motion and truncation. The goal of this project is to extend existing data consistency conditions, which can be practically used for FDCT to remedy intrinsic weaknesses of FDCT imaging, most importantly motion and truncation. Our goal is the practical applicability on clinical data. Thus, the new algorithms will be tested on physical phantom and patient data acquired on real FDCT scanners of our project partners. Our long-term vision behind this project is to find a concise and complete formulation for all redundancies within FDCT projection data for general trajectories and fully exploit them in the reconstruction process. Redundancies are inherent to every FDCT scan done in today´s clinical practice, but they are ignored entirely as a source of information. Data consistency conditions do not require any additional effort during the acquisitions and only little prior knowledge such as the object extent or even no assumptions about the underlying object, unlike for example total variation regularization in iterative reconstruction. Hence, they rely solely on information which is naturally present in the data.

层析成像重建是针对广泛基于传输的3D成像方式的能力技术，最著名的是X射线计算机断层扫描（CT）。建于70年代的第一个CT扫描仪使用了平行的几何形状。为了加快采集的速度，系统很快转移到了风扇梁的几何形状和更快的旋转速度。当今的CT系统每秒旋转四次，并使用锥束几何形状。这足以涵盖复杂的器官运动，例如跳动的心脏。但是，存在大量的专业CT系统，这些系统无法执行如此快速的扫描。使用平板探测器的系统，因为它们在C臂血管造影系统，放射治疗中的板载成像系统或移动C臂系统中使用，因为它们主要是为执行2D成像而面临的机械挑战。大约15年前，扁平探测器扫描仪已被允许获取三维数据。然而，这些系统上的3D成像受到挑战，因为它们的获取速度在五秒钟至一分钟之间，并且直径为25至40厘米的小型视野（FOV）。这些缺点与扫描仪的设计是高度专业的方式。与其他平板探测器（例如增加X射线散射和有限的动态范围）的其他灾难相反，在可预见的将来，硬件演变将无法补救，例如由于操作室有碰撞的风险，更快的运动是不可能的。结果，由于运动和截断，扁平探测器计算机断层扫描（FDCT）将继续更容易受到重建图像中的伪影的影响。该项目的目的是扩展现有的数据一致性条件，该条件实际上可用于FDCT来纠正FDCT成像的固有弱点，最重要的是运动和截断。我们的目标是对临床数据的实际适用性。这是在我们项目合作伙伴的实际FDCT扫描仪上获取的物理幻影和患者数据上测试新算法。该项目背后的长期愿景是为一般轨迹的FDCT项目数据中的所有冗余找到一个简洁而完整的公式，并在重建过程中充分利用它们。冗余是在当今临床实践中所做的每项FDCT扫描继承的，但它们被忽略为信息来源。数据一致性条件在采集期间不需要任何额外的努力，只有很少的先验知识，例如对象范围，甚至没有对基础对象的假设，与例如迭代重建中调节的总变化不同。因此，他们仅依靠数据中自然存在的信息。