Self-adapting cyclic registration for motion-compensated cone-beam CT in image-guided radiation therapy
Self-adapting cyclic registration for motion-compensated cone-beam CT in image-guided radiation therapy
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DOI：
10.1118/1.4766435
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发表时间：
2012-12-01
期刊：
影响因子：
3.8
通讯作者：
Kachelriess, Marc
中科院分区：
文献类型：
--
作者：
Brehm, Marcus;Paysan, Pascal;Kachelriess, Marc
目的：在图像引导放射治疗中，在直线粒子加速器旁边附加一个千伏成像系统，为准确的患者定位提供信息。然而，由于龙门旋转速度较低，系统的采集时间比患者的呼吸周期长得多。我们的目的是在运动补偿图像重建的背景下进行循环配准，为机载平板探测器锥束CT扫描提供高质量的呼吸相关4D体积。方法：基于在配准算法中广泛使用的小运动假设，提出了一种运动估计策略。在这个策略中，时间限制被纳入，例如，呼吸的循环运动模式。由此产生的循环配准方法对图像伪影的灵敏度较低，特别是由于投影数据稀疏造成的伪影。采用一种新的循环配准方法对呼吸相关重构进行运动估计，并利用得到的运动矢量场进行运动补偿。结果：在使用模拟数据和患者数据进行运动补偿图像重建的背景下，对所提出的循环配准进行了评估。通过由此产生的循环运动补偿，可以显著减少三维标准重建的运动伪影。该方法在保持高时间分辨率的同时，在稀疏视图伪影方面优于呼吸相关重建方法。使用循环配准的图像伪影对运动估计只有轻微到几乎没有影响。结论：循环运动补偿方法提供了高质量的呼吸相关体积图像。循环运动估计对稀疏视图伪影的敏感性很低，因此它能够基于低采样数据的重建确定高质量的运动向量场。(C) 2012年美国医学物理学家协会。[http://dx.doi.org/10.1118/1.4766435]
Purpose: In image-guided radiation therapy an additional kV imaging system next to the linear particle accelerator provides information for an accurate patient positioning. However, the acquisition time of the system is much longer than the patient's breathing cycle due to the low gantry rotation speed. Our purpose is a cyclic registration in the context of motion-compensated image reconstruction that provides high quality respiratory-correlated 4D volumes for on-board flat panel detector cone-beam CT scans.Methods: Based on the small motion assumption, widely used within registration algorithms, a strategy is developed for motion estimation. In this strategy temporal restrictions are incorporated, for example, the cyclic motion patterns of respiration. The resultant cyclic registration method is to show less sensitivity on image artifacts, in particular on artifacts due to projection data sparsification. Using a new cyclic registration method a motion estimation is performed on respiratory-correlated reconstructions, and the obtained motion vector fields are used for motion compensation.Results: The proposed cyclic registration is evaluated in the context of motion-compensated image reconstruction using simulated data and patient data. Motion artifacts of 3D standard reconstructions can be significantly reduced by the resulting cyclic motion compensation. The method outperforms the respiratory-correlated reconstructions regarding sparse-view artifacts and maintains the high temporal resolution at the same time. Image artifacts show only minor to almost no effect on the motion estimation using the cyclic registration.Conclusions: The cyclic motion compensation approach provides respiratory-correlated volumes with high image quality. The cyclic motion estimation is of such low sensitivity to sparse-view artifacts, that it is capable to determine high quality motion vector fields based on reconstructions of low sampled data. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4766435]