A practical cone-beam CT scatter correction method with optimized Monte Carlo simulations for image-guided radiation therapy.
A practical cone-beam CT scatter correction method with optimized Monte Carlo simulations for image-guided radiation therapy.
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DOI：
10.1088/0031-9155/60/9/3567
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发表时间：
2015-05-07
影响因子：
3.5
通讯作者：
Jia X
中科院分区：
文献类型：
--
作者：
Xu Y;Bai T;Yan H;Ouyang L;Pompos A;Wang J;Zhou L;Jiang SB;Jia X
锥形束CT （CBCT）已成为图像引导放射治疗中患者设置的标准图像引导工具。然而，由于其较大的照明场，散射光子严重降低了其图像质量。虽然基于核的散射校正方法已在临床中常规使用，但由于其准确性，仍然需要开发基于蒙特卡罗（MC）模拟的方法。然而，MC方法的高计算负担阻碍了常规临床应用。本文报道了我们最近开发的一种实用的基于mc的CBCT散点估计和去除方法。与传统MC方法使用受散射污染的CBCT图像估计散射信号相比，该方法使用规划的CT图像进行MC模拟，具有图像强度准确和没有图像截断的优点。在我们的方法中，首先将规划CT与CBCT进行严格注册。然后通过MC模拟估计散射信号。从原始CBCT投影中去除散射信号后，重建校正后的CBCT图像。整个流程在GPU平台上实现，计算效率高。采用投影去噪、CT图像降采样、沿角方向插值等策略进一步提高计算速度。研究了工作流中关键参数对结果精度和效率的影响，并在此基础上确定了最优参数值。我们的方法在数值模拟、模拟和真实病例中进行了评估。在全扇和半扇情况下，我们的方法分别将平均HU误差从44 HU降低到3 HU和从78 HU降低到9 HU。在幻像和患者病例中，由散射引起的图像伪影，如领结区域周围的环形伪影，都减少了。使用所有技术，我们实现了计算时间小于30秒，包括散点估计和CBCT重建步骤的时间。该方法的有效性和较高的计算效率使其具有临床应用的吸引力。
Cone-beam CT (CBCT) has become the standard image guidance tool for patient setup in image-guided radiation therapy. However, due to its large illumination field, scattered photons severely degrade its image quality. While kernel-based scatter correction methods have been used routinely in the clinic, it is still desirable to develop Monte Carlo (MC) simulation-based methods due to their accuracy. However, the high computational burden of the MC method has prevented routine clinical application. This paper reports our recent development of a practical method of MC-based scatter estimation and removal for CBCT. In contrast with conventional MC approaches that estimate scatter signals using a scatter-contaminated CBCT image, our method used a planning CT image for MC simulation, which has the advantages of accurate image intensity and absence of image truncation. In our method, the planning CT was first rigidly registered with the CBCT. Scatter signals were then estimated via MC simulation. After scatter signals were removed from the raw CBCT projections, a corrected CBCT image was reconstructed. The entire workflow was implemented on a GPU platform for high computational efficiency. Strategies such as projection denoising, CT image downsampling, and interpolation along the angular direction were employed to further enhance the calculation speed. We studied the impact of key parameters in the workflow on the resulting accuracy and efficiency, based on which the optimal parameter values were determined. Our method was evaluated in numerical simulation, phantom, and real patient cases. In the simulation cases, our method reduced mean HU errors from 44 HU to 3 HU and from 78 HU to 9 HU in the full-fan and the half-fan cases, respectively. In both the phantom and the patient cases, image artifacts caused by scatter, such as ring artifacts around the bowtie area, were reduced. With all the techniques employed, we achieved computation time of less than 30 sec including the time for both the scatter estimation and CBCT reconstruction steps. The efficacy of our method and its high computational efficiency make our method attractive for clinical use.
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DOI：
10.1016/s0360-3016(02)02884-5
发表时间：
2002-08-01
影响因子：
7
作者：
Jaffray, DA;Siewerdsen, JH;Martinez, AA
通讯作者：
Martinez, AA
影响因子：
3.5
作者：
CHO, PS;JOHNSON, RH;GRIFFIN, TW
通讯作者：
GRIFFIN, TW
影响因子：
3.8
作者：
Jia, Xun;Yan, Hao;Jiang, Steve B.
通讯作者：
Jiang, Steve B.
影响因子：
3.5
作者：
Kyriakou, Yiannis;Riedel, Thomas;Kalender, Willi A.
通讯作者：
Kalender, Willi A.
影响因子：
2.5
作者：
Fedorov, Andriy;Beichel, Reinhard;Kalpathy-Cramer, Jayashree;Finet, Julien;Fillion-Robin, Jean-Christophe;Pujol, Sonia;Bauer, Christian;Jennings, Dominique;Fennessy, Fiona;Sonka, Milan;Buatti, John;Aylward, Stephen;Miller, James V.;Pieper, Steve;Kikinis, Ron
通讯作者：
Kikinis, Ron