Reducing Residual-Motion Artifacts in Iterative 3D CBCT Reconstruction in Image-Guided Radiation Therapy.
Reducing Residual-Motion Artifacts in Iterative 3D CBCT Reconstruction in Image-Guided Radiation Therapy.
复制标题
减少图像引导放射治疗中迭代 3D CBCT 重建中的残余运动伪影。
DOI：
10.1002/mp.15236
复制
发表时间：
2021
期刊：
影响因子：
3.8
通讯作者：
D. Seghers
中科院分区：
文献类型：
--
作者：
I. Peterlík;A. Strzelecki;M. Lehmann;P. Messmer;P. Munro;P. Paysan;M. Plamondon;D. Seghers
目的
最近对瓦里安放射治疗设备上可用的三维迭代锥束CT(ICBCT)重建方法的评估表明，与分析性FDK方法相比，iCBCT提供了更好的图像质量。然而，iCBCT使用了统计惩罚似然(PL)，它对由于采集过程中发生的生理运动而引起的不一致非常敏感。我们提出了一种计算成本较低的iCBCT扩展，以解决这一不足。
方法
在迭代过程中，修改了PL的梯度，以避免产生与运动相关的伪影。为了评估这一修改的影响，我们提出了一个运动模拟，生成运动解剖的CBCT投影以及用作地面真实的无伪影图像。计算不同图像的对比度噪声比和功率谱，以量化运动对重建的CBCT体积的影响以及拟议的图像修改的影响。
结果
使用模拟和临床数据表明，采集过程中患者腹壁的运动会产生伪影，这些伪影可以量化为iCBCT重建的体积中的低频分量。此外，定量评估表明，拟议的PL修改减少了这些低频分量。在保留PL优势的同时，有效地抑制了运动相关伪影向临床重要区域的传播，从而提高了iCBCT的运动弹性。
结论
提出的改进迭代重建方法显著提高了存在残余运动的解剖的CBCT图像质量。
PURPOSE
Recent evaluations of a 3D iterative cone-beam CT (iCBCT) reconstruction method available on Varian radiation treatment devices demonstrated that iCBCT provides superior image quality when compared to analytical FDK method. However, iCBCT employs statistical penalized likelihood (PL) which is known to be highly sensitive to inconsistencies due to physiological motion occurring during the acquisition. We propose a computationally inexpensive extension of iCBCT addressing this deficiency.
METHODS
During the iterative process, the gradients of PL are modified in order to avoid the generation of motion-related artifacts. To assess the impact of this modification, we propose a motion simulation generating CBCT projections of a moving anatomy together with artifact-free images used as ground truth. Contrast-to-noise ratio and power spectra of difference images are computed to quantify the impact of the motion on reconstructed CBCT volumes as well as the effect of the proposed modification.
RESULTS
Using both simulated and clinical data it is shown that the motion of patient's abdominal wall during the acquisition results in artifacts which can be quantified as low-frequency components in volumes reconstructed with iCBCT. Further, a quantitative evaluation demonstrates that the proposed modification of PL reduces these low-frequency components. While preserving the advantages of PL, it effectively suppresses the propagation of motion-related artifacts into clinically important regions, thus increasing the motion resiliency of iCBCT.
CONCLUSIONS
The proposed modified iterative reconstruction method significantly improves the quality of CBCT images of anatomies suffering from residual motion.