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用锥形束CT图像引导技术分析肺癌放疗摆位误差及其对剂量分布影响
曹晓辉, 刘明, 翟福山, 王安峰, 杨永锋, 刘兵, 包超恩
050051 石家庄, 河北医科大学第三医院放疗科
Analysis of setup errors and its impact on dosimetric distribution for thoracic carcinoma radiotherapy with cone-beam CT-based image guidance
CAO Xiao-hui, LIU Ming, ZHAI Fu-shan, WANG An-feng, YANG Yong-feng, LIU Bing, BAO Chao-en
Department of Radiation Oncology, Third Hospital of Hebei Medical University, Shijiazhuang 050051, China Corresponding author:Email:lming65@yahoo.com.cn
Abstract：Objective To study the role of kilovolt cone beam CT (CBCT) on the geometrical accuracy of three-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) and to analyze the effect of the setup error on the dosimetric distribution of targets and peripheral organs at risk for thoracic carcinoma. Methods 23 patients with thoracic carcinoma were collected. Varian-IX linear accelerator on-board imaging system was used to acquire CBCT scans in 3DCRT or IMRT before delivery. The right-left (x), superior-inferior (y), anterior-posterior (z) setup errors can be obtained from the images automatically restructured by the system. And then CMS treatment planning system was used to analyze the impact of setup errors on dosimetric distribution of targets and peripheral organs at risk if the isocenter was replaced by the actual location which obtained from the CBCT scan. Results The setup error were －0.181 mm, －0.429 mm, －2.637 mm respectively and the absolute maximum was 13 mm, 21 mm, 8 mm respectively according to 182 CBCT scans on x, y, z directions. Within 5 mm of which accounted for 93.9%, 71.4%, 81.9% respectively. Target dose reduced with respect to treatment plan, mean value were 89.7%(F=7.04,P=0.011), 97.9%, 95.5% and 98.8%(F=0.32,1.68,0.11;P=0.572,0.201,0.740) for PTV D95%, PTV Dmean, GTV D95% and GTV Dmean. Mean value of the difference in normal organ dose were 102.7%, 103.1%, 105.0%, 110.6%, 103.0%, 98.1% for the volume of lung accept 5 Gy, 10 Gy, 20 Gy, 30 Gy, the mean dose of lung, the maximum dose of 1 cm3 spinal cord. The difference of PTV D95% was significant if setup errors more than 5 mm in any direction (F=14.58,P=0.001). Conclusions Setup errors of this group mostly within 5 mm. It was more obvious in the y directions. There was significantly difference if setup errors more than 5 mm in any direction.
CAO Xiao-hui,LIU Ming,ZHAI Fu-shan et al. Analysis of setup errors and its impact on dosimetric distribution for thoracic carcinoma radiotherapy with cone-beam CT-based image guidance[J]. Chinese Journal of Radiation Oncology, 2012, 21(2): 163-165.
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2012, Vol. 21 
