Saito Tetsuo, Matsuyama Tomohiko, Toya Ryo, Fukugawa Yoshiyuki, Toyofuku Takamasa, Semba Akiko, Oya Natsuo
Department of Radiation Oncology, Kumamoto University Hospital, Kumamoto, Japan.
PLoS One. 2014 Nov 7;9(11):e112824. doi: 10.1371/journal.pone.0112824. eCollection 2014.
We evaluated the effects of respiratory gating on treatment accuracy in lung cancer patients undergoing lung stereotactic body radiotherapy by using electronic portal imaging device (EPID) images.
Our study population consisted of 30 lung cancer patients treated with stereotactic body radiotherapy (48 Gy/4 fractions/4 to 9 days). Of these, 14 were treated with- (group A) and 16 without gating (group B); typically the patients whose tumors showed three-dimensional respiratory motion ≧5 mm were selected for gating. Tumor respiratory motion was estimated using four-dimensional computed tomography images acquired during treatment simulation. Tumor position variability during all treatment sessions was assessed by measuring the standard deviation (SD) and range of tumor displacement on EPID images. The two groups were compared for tumor respiratory motion and position variability using the Mann-Whitney U test.
The median three-dimensional tumor motion during simulation was greater in group A than group B (9 mm, range 3-30 mm vs. 2 mm, range 0-4 mm; p<0.001). In groups A and B the median SD of the tumor position was 1.1 mm and 0.9 mm in the craniocaudal- (p = 0.24) and 0.7 mm and 0.6 mm in the mediolateral direction (p = 0.89), respectively. The median range of the tumor position was 4.0 mm and 3.0 mm in the craniocaudal- (p = 0.21) and 2.0 mm and 1.5 mm in the mediolateral direction (p = 0.20), respectively.
Although patients treated with respiratory gating exhibited greater respiratory tumor motion during treatment simulation, tumor position variability in the EPID images was low and comparable to patients treated without gating. This demonstrates the benefit of respiratory gating.
我们使用电子射野影像装置（EPID）图像评估了呼吸门控对接受肺部立体定向体部放疗的肺癌患者治疗准确性的影响。
我们的研究对象包括30例接受立体定向体部放疗（48 Gy/4次分割/4至9天）的肺癌患者。其中，14例接受门控治疗（A组），16例未接受门控治疗（B组）；通常选择肿瘤三维呼吸运动≥5 mm的患者进行门控。使用治疗模拟期间采集的四维计算机断层扫描图像估计肿瘤呼吸运动。通过测量EPID图像上肿瘤位移的标准差（SD）和范围，评估所有治疗疗程中肿瘤位置的变异性。使用Mann-Whitney U检验比较两组的肿瘤呼吸运动和位置变异性。
模拟期间A组肿瘤的三维运动中位数大于B组（9 mm，范围3 - 30 mm vs. 2 mm，范围0 - 4 mm；p<0.001）。在A组和B组中，肿瘤位置的SD中位数在头脚方向分别为1.1 mm和0.9 mm（p = 0.24），在内外侧方向分别为0.7 mm和0.6 mm（p = 0.89）。肿瘤位置的范围中位数在头脚方向分别为4.0 mm和3.0 mm（p = 0.21），在内外侧方向分别为2.0 mm和1.5 mm（p = 0.20）。
尽管接受呼吸门控治疗的患者在治疗模拟期间表现出更大的肿瘤呼吸运动，但EPID图像中肿瘤位置的变异性较低，与未接受门控治疗的患者相当。这证明了呼吸门控的益处。
