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Analysis of the inter-and intra-fraction setup errors and residual errors during stereotactic radiotherapy for brain metastasis
Zhang Yanxin, Fu Guishan, Xu Yingjie, Chen Bing, Fang Hao, Liu Bofei, Liu Qingfeng, Xiao Jianping, Dai Jianrong
Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences ( CAMS ) and Peking Union Medical College (PUMC),Beijing 100021,China
AbstractObjective To evaluate the necessity of arc by arc setup verification in patients with brain metastases receiving stereotactic radiotherapy (SRT) by analyzing the inter-and intra-fraction setup errors and residual errors collected from the ExacTrac X-ray portal image.Methods Clinical data of brain metastases patients treated with SRT in the previous two years were retrospectively analyzed. The ExacTrac X-ray setup images were collected after the normal setup procedure. Setup errors were calculated by registering the cranial bony structures of the ExacTrac X-ray setup images to that of the digitally reconstructed setup images. The inter-and intra-fraction setup errors and residual errors were statistically analyzed.Results Seventy-five patients from 116 lesions received 337 cycles of SRT of the head. The inter-and intra-fraction translational setup errors in the x,yand zdirections were (0.93±0.86) mm and (0.15±0.59) mm;(1.83±1.27) mm and (0.25±0.73) mm;(0.96±0.80) mm and (0.14±0.56) mm,respectively. The inter-and intra-fraction rotational setup errors in the x,y,zdirections were (0.65°±0.62°) and (0.19°±0.40°);(0.97°±0.94°) and (0.13°±0.25°);(0.92°±0.71°) and (0.10°±0.29°),respectively. The residual translational setup errors in the x,y,zdirections were (0.06±0.23) mm,(0.08±0.24) mm and (0.08±0.22) mm,and (0.12°±0.27°),(0.09°±0.18°) and (0.06°±0.19°) for the residual rotational setup errors,respectively. For a reference setup error threshold of 0.7 mm/0.7°,99.1% of the SRT exceeded the threshold and required setup correction. For 1 006 non-coplanar arcs,rotating the treatment couch from 0° to the treatment angle made 66.4% of arcs exceed the threshold and require at least once setup correction.Conclusions During SRT for brain metastasis,the inter-and intra-fraction setup errors should be emphasized. It is necessary to perform arc by arc setup error verification.
Fund:Beijing Hope Run Special Fund of Cancer Foundation of China(LC2015B02);National Key Projects of Research and Development of China (2016YFC0904600) ;Chinese Academy of Medical Science (CAMS) Innovation Fund for Medical Sciences (CIFMS, 2016-I2M-1-001)
Corresponding Authors:
Fu Guishan,Email:guishan11@163.com;Xu Yingjie,Email:xuyingjie08@126.com
Cite this article:
Zhang Yanxin,Fu Guishan,Xu Yingjie et al. Analysis of the inter-and intra-fraction setup errors and residual errors during stereotactic radiotherapy for brain metastasis[J]. Chinese Journal of Radiation Oncology, 2019, 28(6): 448-451.
Zhang Yanxin,Fu Guishan,Xu Yingjie et al. Analysis of the inter-and intra-fraction setup errors and residual errors during stereotactic radiotherapy for brain metastasis[J]. Chinese Journal of Radiation Oncology, 2019, 28(6): 448-451.
2019, Vol. 28 
