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肝癌术后简化调强放疗临床靶体积误差的锥形束CT分析
张涛, 王维虎, 金晶, 王淑莲, 宋永文, 刘跃平, 戴建荣, 李晔雄
100021 北京,中国医学科学院北京协和医学院肿瘤医院肿瘤研究所放疗科
Analysis of clinical target volume positioning errors using cone beam computed tomography for patients with liver tumors with postoperative simplefied intensity-modulated radiotherapy
ZHANG Tao, WANG Wei-hu, JIN Jing, WANG Shu-lian, SONG Yong-wen, LIU Yue-ping, DAI Jian-rong, LI Ye-xiong
Department of Radiation Oncology, Cancer Institute (Hospital), Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100021, China Corresponding author:WANG Wei-hu, Email:weihu06@yahoo.com.cn;LI Ye-xiong yexiong3@yahoo.com.cn
Abstract：Objective To evaluate the inter-and intra-fractional clinical target volume (CTV) positioning errors of patients receiving postoperative simplified intensity-modulated radiotherapy (SIMRT) using cone beam computed tomography (CBCT). Methods Twelve patients with liver tumors underwent postoperative SIMRT. CBCT images were acquired before and after the treatment. The clipbox volume for registration included the fiducial markers in the tumor bed and excluded the ribs and vertebral bodies. If any translational parameter of setup error before treatment exceeded 3 mm or rotational parameter exceeded 3°, the treatment couch was adjusted and a verification CBCT was acquired to assess residual setup error. Automatic bone match was used. A total of 214 acquisitions of CBCTs in 111 groups were analyzed. Inter-fractional translational CTV positioning errors in left-right (x), superior-inferior (y) and anterior-posterior (z) axis were calculated in 111 groups, and intra-fractional translational CTV positioning errors in 70 groups. Clinical to planning target volume (PTV) margins were calculated according to the formula:margin= 2.0∑+0.7σ(∑ is systematic error,σ is random error). Results Inter-fractional translational CTV positioning errors in x, y and z axis were －0.03 mm,－0.43 mm,1.02 mm,with systematic error (∑) of 1.50 mm, 5.89 mm, 1.97 mm, and random error (σ) of 1.76 mm, 4.13 mm, 2.42 mm, respectively. Intra-fractional translational CTV positioning errors in the x, y, z axis were 0.04 mm,0.86 mm,－0.46 mm, with systematic error (∑) of 0.46 mm, 1.14 mm, 0.31 mm, and random error (σ) of 0.95 mm, 1.38 mm, 0.91 mm,respectively. The calculate CTV to PTV margins were 4.5 mm, 15.0 mm, 5.8 mm in the x, y, z axis, respectively. Conclusions The CTV errors were inevitable when patientswith liver tumors received SIMRT. Fiducial markers placed in tumor bed during operation were helpful for accurate positioning error analysis.
ZHANG Tao,WANG Wei-hu,JIN Jing et al. Analysis of clinical target volume positioning errors using cone beam computed tomography for patients with liver tumors with postoperative simplefied intensity-modulated radiotherapy[J]. Chinese Journal of Radiation Oncology, 2012, 21(4): 361-363.
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