Measurement of lung tumor motion using respiration-correlated CT
Measurement of lung tumor motion using respiration-correlated CT
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DOI：
10.1016/j.ijrobp.2004.06.021
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发表时间：
2004-11-01
影响因子：
7
通讯作者：
Ling, CC
中科院分区：
文献类型：
--
作者：
Mageras, GS;Pevsner, A;Ling, CC
目的：我们研究通过呼吸相关计算机断层扫描（RCCT）测量的肺部肿瘤运动特征，并检验该方法在放射治疗计划和治疗中的适用性。
方法和材料：6名非小细胞肺癌患者接受了螺旋单层计算机断层扫描（CT），扫描床缓慢移动（1毫米/秒），同时用外部位置敏感监测器记录呼吸。另外6名患者以电影模式接受4层CT扫描，在每个扫描床位置获取一个完整呼吸周期的连续图像，同时记录呼吸。根据外部监测器测量结果（4层数据）或图像中观察到的患者体表位移（单层数据），将图像回顾性地分类到不同呼吸阶段。在一个阶段描绘肺部的大体肿瘤体积（GTV），作为在其他阶段描绘的视觉指导。通过将治疗时门控射线照片中测量的膈肌位置变化按照RCCT数据中观察到的GTV与膈肌位移的比率进行缩放，来估计分次间GTV的变化。
结果：12名患者中有7名显示GTV随呼吸的位移超过1厘米，主要在上下（SI）方向；2名患者显示前后位移超过1厘米。在所有病例中，GTV在SI方向的极限位置与外部测量的呼吸极限一致。3名患者显示GTV运动存在滞后现象，即肿瘤轨迹在呼气时相对于吸气时向前位移0.2至0.5厘米。1名患者观察到GTV在SI方向随呼吸显著（>1厘米）扩张。在所有病例中，估计在呼气末进行门控治疗时的分次内GTV运动为0.6厘米或更小；然而，在3/9名患者中，分次间变化估计值（系统误差加随机误差）超过1厘米。
结论：利用现有的CT设备和采集设置可以进行呼吸相关CT扫描。RCCT不仅提供了分次内肿瘤运动和变形的三维信息，而且当与治疗期间膈肌位置变化的射线照相测量相结合时，还可以估计分次间肿瘤的变化。（C）2004爱思唯尔公司
Purpose: We investigate the characteristics of lung tumor motion measured with respiration-correlated computed tomography (RCCT) and examine the method's applicability to radiotherapy planning and treatment.Methods and Materials: Six patients treated for non-small-cell lung carcinoma received a helical single-slice computed tomography (CT) scan with a slow couch movement (1 mm/s), while simultaneously respiration is recorded with an external position-sensitive monitor. Another 6 patients receive a 4-slice CT scan in a cine mode, in which sequential images are acquired for a complete respiratory cycle at each couch position while respiration is recorded. The images are retrospectively resorted into different respiration phases as measured with the external monitor (4-slice data) or patient surface displacement observed in the images (single-slice data). The gross tumor volume (GTV) in lung is delineated at one phase and serves as a visual guide for delineation at other phases. Interfractional GTV variation is estimated by scaling diaphragm position variations measured in gated radiographs at treatment with the ratio of GTV:diaphragm displacement observed in the RCCT data.Results: Seven out of 12 patients show GTV displacement with respiration of more than 1 cm, primarily in the superior-inferior (SI) direction; 2 patients show anterior-posterior displacement of more than I cm. In all cases, extremes in GTV position in the SI direction are consistent with externally measured extremes in respiration. Three patients show evidence of hysteresis in GTV motion, in which the tumor trajectory is displaced 0.2 to 0.5 cm anteriorly during expiration relative to inspiration. Significant (>1 cm) expansion of the GTV in the SI direction with respiration is observed in 1 patient. Estimated intrafractional GTV motion for gated treatment at end expiration is 0.6 cm or less in all cases; however; interfraction variation estimates (systematic plus random) are more than 1 cm in 3/9 patients.Conclusion: Respiration-correlated CT can be performed with currently available CT equipment and acquisition settings. RCCT provides not only three-dimensional information on intrafractional tumor motion and deformation, but also allows estimates of interfractional tumor variation when combined with radiographic measurements of diaphragm position variation during treatment. (C) 2004 Elsevier Inc.