The purpose of this work is to develop a procedure for commissioning four‐dimensional computed tomography (4DCT) algorithms for minimum target reconstruction size, to quantify the effect of anterior–posterior (AP) motion artifacts on known object reconstruction for periodic and irregular breathing patterns, and to provide treatment planning recommendations for target sizes below a minimum threshold. A mechanical platform enabled AP motion of a rod and lung phantom during 4DCT acquisition. Static, artifact‐free scans of the phantoms were first acquired. AP sinusoidal and patient breathing motion was applied to obtain 4DCT images. 4DCT reconstruction artifacts were assessed by measuring the apparent width and angle of the rod. Comparison of known tumor diameters and volumes between the static image parameters with the 4DCT image sets was used to quantify the extent of AP reconstruction artifact and contour deformation. Examination of the rod width, under sinusoidal motion, found it was best represented during the inhale and exhale phases for all periods and ranges of motion. From the gradient phases, the apparent width of the rod decreased with increasing amplitude and decreasing period. The rod angle appeared larger on the reconstructed images due to the presence of motion artifact. The apparent diameters of the spherical tumors on the gradient phases were larger/equivalent than the true values in the AP/LR direction, respectively, while the exhale phase consistently displayed the spheres at the approximately correct diameter. The Eclipse calculated diameter matched closely with the true diameter on the exhale phase and was found to be larger on the inhale, MIP, and Avg scans. The procedure detailed here may be used during the acceptance and commissioning period of a computed tomography simulator or retroactively when implementing a SBRT program to determine the minimum target size that can be reliably reconstructed.

中文翻译：

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试运行一个二维计算机断层摄影模拟器，以使由于前后方向的运动而导致的最小目标尺寸最小化：一种程序和治疗计划建议。

这项工作的目的是开发一种程序，以调试用于最小目标重建尺寸的四维计算机断层扫描（4DCT）算法，以量化前后（AP）运动伪影对已知对象重建的周期性和不规则呼吸模式的影响，并针对低于最小阈值的目标大小提供治疗计划建议。一个机械平台使4DCT采集过程中AP和视杆幻影运动。首先获得了对模型的静态无伪影扫描。应用AP正弦曲线和患者呼吸运动以获取4DCT图像。通过测量杆的表观宽度和角度来评估4DCT重建伪像。静态图像参数与4DCT图像集之间已知肿瘤直径和体积的比较用于量化AP重建伪影和轮廓变形的程度。在正弦运动下检查杆的宽度，发现在所有阶段和运动范围的吸气和呼气阶段均能最好地代表杆的宽度。从梯度阶段开始，杆的表观宽度随振幅的增加和周期的减小而减小。由于运动伪影的存在，杆角度在重建图像上显得更大。梯度相上球形肿瘤的表观直径分别大于/等效于AP / LR方向上的真实值，而呼气相则始终以近似正确的直径显示球体。Eclipse计算出的直径与呼气阶段的真实直径紧密匹配，并且在吸气，MIP和Avg扫描中发现更大。此处详述的过程可以在计算机断层扫描模拟器的接受和调试期间使用，也可以在实施SBRT程序时追溯以确定可以可靠重建的最小目标尺寸。