Impact of scanning parameters and breathing patterns on image quality and accuracy of tumor motion reconstruction in 4D CBCT: a phantom study.
Impact of scanning parameters and breathing patterns on image quality and accuracy of tumor motion reconstruction in 4D CBCT: a phantom study.
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DOI：
10.1120/jacmp.v16i6.5620
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发表时间：
2015-11-08
影响因子：
2.1
通讯作者：
Sanjiv SS
中科院分区：
文献类型：
--
作者：
Lee S;Yan G;Lu B;Kahler D;Li JG;Sanjiv SS
四维锥形束CT（4D CBCT）大大减少了三维（3D）CBCT中呼吸诱导的运动模糊伪影。然而，4D CBCT的图像质量显著下降，这可能影响其定位移动的肿瘤以进行高精度图像引导放射治疗（IGRT）的准确性。本研究的目的是研究扫描参数（以下统称为扫描序列）和呼吸模式对商业4D CBCT系统的图像质量和计算肿瘤轨迹的准确性的影响，为其临床实施做准备。我们模拟了一系列的周期性和非周期性的正弦呼吸模式与呼吸运动模型。通过改变单个正弦呼吸周期的周期或幅度来创建非周期性模式。使用制造商提供的扫描序列（4D-S-slow）和两个内部修改的扫描序列（4D-M-slow和4D-M-fast）获取体模的4D CBCT扫描。4D-S-slow使用小视场（FOV）、部分旋转（200°）和无成像滤波器，而4D-M-slow和4D-M-fast使用中等FOV、完全旋转和F1滤波器。在4D-M-fast（机架旋转100°/min）中，扫描速度加倍。使用对比噪声比（CNR）、信噪比（SNR）和运动模糊比（MBR）评价4D CBCT扫描的图像质量。通过将4D CBCT的每个相位与参考CT配准来重建运动目标的轨迹。均方根误差（RMSE）分析用于量化其准确性。观察到从3D CBCT到4D CBCT的CNR和SNR显著降低。4D-S-slow和4D-M-fast扫描的图像质量相当，而4D-M-slow扫描由于投影加倍而具有更好的性能。CNR和SNR都随着呼吸周期的增加而略有下降，但没有观察到对幅度的依赖性。周期性和非周期性呼吸模式的CNR和SNR差异不显著（）。在呼气末阶段，周期性和非周期性呼吸模式的运动模糊可忽略不计;在吸气中期阶段，运动模糊随着周期、振幅或振幅的周期间变化量的增加而增加。总体而言，在所有研究病例中，4D CBCT中定位移动靶的准确性均在2 mm以内。三种扫描序列的RMSE无差异。由于使用了更快的机架旋转和F1滤波器，4D-M-快速扫描（无体积截断伪影）在肿瘤运动重建中表现出与4D-S-慢速扫描相当的图像质量和准确性，但成像剂量降低（0.60 cGy vs. 0.99 cGy），表明其适用于临床使用。PACS编号：87.55.Qr
Four‐dimensional, cone‐beam CT (4D CBCT) substantially reduces respiration‐induced motion blurring artifacts in three‐dimension (3D) CBCT. However, the image quality of 4D CBCT is significantly degraded which may affect its accuracy in localizing a mobile tumor for high‐precision, image‐guided radiation therapy (IGRT). The purpose of this study was to investigate the impact of scanning parameters (hereinafter collectively referred to as scanning sequence) and breathing patterns on the image quality and the accuracy of computed tumor trajectory for a commercial 4D CBCT system, in preparation for its clinical implementation. We simulated a series of periodic and aperiodic sinusoidal breathing patterns with a respiratory motion phantom. The aperiodic pattern was created by varying the period or amplitude of individual sinusoidal breathing cycles. 4D CBCT scans of the phantom were acquired with a manufacturer‐supplied scanning sequence (4D‐S‐slow) and two in‐house modified scanning sequences (4D‐M‐slow and 4D‐M‐fast). While 4D‐S‐slow used small field of view (FOV), partial rotation (200°), and no imaging filter, 4D‐M‐slow and 4D‐M‐fast used medium FOV, full rotation, and the F1 filter. The scanning speed was doubled in 4D‐M‐fast (100°/min gantry rotation). The image quality of the 4D CBCT scans was evaluated using contrast‐to‐noise ratio (CNR), signal‐to‐noise ratio (SNR), and motion blurring ratio (MBR). The trajectory of the moving target was reconstructed by registering each phase of the 4D CBCT with a reference CT. The root‐mean‐squared‐error (RMSE) analysis was used to quantify its accuracy. Significant decrease in CNR and SNR from 3D CBCT to 4D CBCT was observed. The 4D‐S‐slow and 4D‐M‐fast scans had comparable image quality, while the 4D‐M‐slow scans had better performance due to doubled projections. Both CNR and SNR decreased slightly as the breathing period increased, while no dependence on the amplitude was observed. The difference of both CNR and SNR between periodic and aperiodic breathing patterns was insignificant (). At end‐exhale phases, the motion blurring was negligible for both periodic and aperiodic breathing patterns; at mid‐inhale phase, the motion blurring increased as the period, the amplitude or the amount of cycle‐to‐cycle variation on amplitude increased. Overall, the accuracy of localizing the moving target in 4D CBCT was within 2 mm under all studied cases. No difference in the RMSEs was noticed among the three scanning sequences. The 4D‐M‐fast scans, free of volume truncation artifacts, exhibited comparable image quality and accuracy in tumor motion reconstruction as the 4D‐S‐slow scans with reduced imaging dose (0.60 cGy vs. 0.99 cGy) due to the use of faster gantry rotation and the F1 filter, suggesting its suitability for clinical use. PACS number: 87.55.Qr
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DOI：
10.1016/j.ijrobp.2005.03.035
发表时间：
2005-07-15
影响因子：
7
作者：
Létourneau, D;Martinez, AA;Wong, J
通讯作者：
Wong, J
影响因子：
3.5
作者：
Dietrich, Lars;Jetter, Siri;Oelfke, Uwe
通讯作者：
Oelfke, Uwe
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：
5.7
作者：
Oldham, M;Létourneau, D;Wong, JW
通讯作者：
Wong, JW
影响因子：
3.5
作者：
Li, T;Schreibmann, E;Xing, L
通讯作者：
Xing, L