Evaluation of respiratory movement during gated radiotherapy using film and electronic portal imaging
Evaluation of respiratory movement during gated radiotherapy using film and electronic portal imaging
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DOI：
10.1016/s0360-3016(01)02681-5
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发表时间：
2002-02-01
影响因子：
7
通讯作者：
Ling, CC
中科院分区：
文献类型：
--
作者：
Ford, EC;Mageras, GS;Ling, CC
目的：为了评估商业系统的有效性，减少呼吸引起的治疗不确定性门控辐射delivery.Methods和Materials：门控系统在这里考虑的措施呼吸从病人的胸部上的反射标记的位置。在预期呼吸时相（6例在呼气末，2例在吸气末）获得8例患者（4例肺部，4例肝脏）的呼吸触发计划CT扫描。此外，荧光透视电影与呼吸波形同时记录。在治疗过程中，使用门控定位片测量横膈膜相对于椎体的位置，并与呼吸触发计划CT的参考数字重建X线片进行比较。通过平均位置的标准差量化变异性。我们还评估了interfraction变异性的软组织结构在门控治疗过程中2例使用非晶硅电子门户imaging device.Results：门控定位电影显示interfraction患者平均隔膜变异性为2.8 +/- 1.0 mm（误差线表示在患者人群的标准差）。X线透视数据显示患者平均分次内横膈膜变异性为2.6 +/- 1.7 mm。无门控时，该分次内偏移变为6.9 +/- 2.1 mm。在门控定位片中，横膈膜相对于计划位置的患者平均平均位移为0.0 +/- 3.9 mm。然而，在8例患者中的4例中，平均（过定位片）位移>4 mm，表明治疗位置与计划位置之间存在系统性位移。在门控治疗期间，在几个部分的射野图像中观察到的软组织特征的位置显示平均变异性在2.6和5.7 mm之间。然而，部分内变异性在0.6和1.4 mm之间，表明大部分变异性是由于患者设置错误而不是呼吸运动。这里评估的门控系统减少了由于呼吸运动引起的解剖结构的分次内和分次间变异性。然而，在某些情况下，在模拟时的解剖特征位置与治疗期间的位置之间观察到系统性位移。建议使用胶片或射野成像进行频繁监测。(C)2002年爱思唯尔科技有限公司
Purpose: To evaluate the effectiveness of a commercial system in reducing respiration-induced treatment uncertainty by gating the radiation delivery.Methods and Materials: The gating system considered here measures respiration from the position of a reflective marker on the patient's chest. Respiration-triggered planning CT scans were obtained for 8 patients (4 lung, 4 liver) at the intended phase of respiration (6 at end expiration and 2 at end inspiration). In addition, fluoroscopic movies were recorded simultaneously with the respiratory waveform. During the treatment sessions, gated localization films were used to measure the position of the diaphragm relative to the vertebral bodies, which was compared to the reference digitally reconstructed radiograph derived from the respiration-triggered planning CT. Variability was quantified by the standard deviation about the mean position. We also assessed the interfraction variability of soft tissue structures during gated treatment in 2 patients using an amorphous silicon electronic portal imaging device.Results: The gated localization films revealed an interfraction patient-averaged diaphragm variability of 2.8 +/- 1.0 mm (error bars indicate standard deviation in the patient population). The fluoroscopic data yielded a patient-averaged intrafraction diaphragm variability of 2.6 +/- 1.7 mm. With no gating, this intrafraction excursion became 6.9 +/- 2.1 mm. In gated localization films, the patient-averaged mean displacement of the diaphragm from the planning position was 0.0 +/- 3.9 mm. However, in 4 of the 8 patients, the mean (over localization films) displacement was >4 mm, indicating a systematic displacement in treatment position from the planned one. The position of soft tissue features observed in portal images during gated treatments over several fractions showed a mean variability between 2.6 and 5.7 mm. The intrafraction variability, however, was between 0.6 and 1.4 mm, indicating that most of the variability was due to patient setup errors rather than to respiratory motion.Conclusions: The gating system evaluated here reduces the intra- and interfraction variability of anatomy due to respiratory motion. However, systematic displacements were observed in some cases between the location of an anatomic feature at simulation and its location during treatment. Frequent monitoring is advisable with film or portal imaging. (C) 2002 Elsevier Science Inc.