关键词: 全脊柱, 多中心, 转移瘤, 放射治疗

Abstract: Objective To investigate the application of volumetric modulated arc therapy（VMAT） in the radiotherapy for multiple bone metastases in the whole spine,and observe of efficacy and evaluation of safety．Methods The clinical data were selected from 50 patients who were treated in our department between January 2018 and January 2021 with palliative analgesic radiotherapy for multiple metastases of the whole spine．Conformal radiotherapy（CRT）and multicenter VMAT plans were respectively applied to target areas of whole spine,and dose volume histogram was used to evaluate the dose coverage of target area and organ at risk（OAR）. After radiotherapy,the short-term efficacy was evaluated by visual analog scale in between 1-8 weeks,and the whole spine MRI was reviewed every 3 months to observe the adverse reactions of radiotherapy．Results The dose coverage,target conformality index and homogeneity index of VMAT treatment were significantly better than those of CRT treatment（P<0.01）,and no obvious dose hotspots and cold spots were observed in the overlapping area of irradiation field. When VMAT treatment was applied,the exposure volume of V5 Gy in OAR was significantly higher when compared with CRT treatment（P<0.01）．Except for stomach,pancreas and small intestine,the exposure volume of V10 Gy in OAR was significantly higher for VMAT treatment when compared with CRT treatment （P<0.01 or P<0.05）．When VMAT treatment was applied,the exposure volume of V20 Gy in OAR was significantly lower when compared with CRT treatment（P<0.01）,and except for kidney,the exposure volume of V30 Gy in OAR was significantly lower when compared with CRT treatment（P<0.01）．When VMAT treatment was applied,the maximum exposure of OAR was significantly lower than that of CRT（P<0.01 or P<0.05）,however,except for the heart,pancreas and small intestine,the average exposure of VMAT treatment to OAR was higher than that of CRT （P<0.01 or P<0.05）．Compared with CRT,VMAT treatment had significantly increased beam-out time（P<0.01）,the therapist setting time of CRT was increased when compared with that of VMAT（P<0.05）,and the total treatment time of VMAT was increased when compared with that of CRT（P<0.01）. In the assessment 8 weeks after the treatments,16 patients had complete pain relief,22 had partial relief,8 had mild relief,and 4 had no effect,which total effective rate was 76%．The follow-up was ended in December 2021．There was no acute or chronic injury to the spinal cord and other tissues in the overlapping areas of the irradiation fields observed for all follow-up patients in the 3rd,6th,9th and 12th month whole-spine MRI re-examination．Conclusions VMAT has uniform dose distribution in multi-center radiotherapy for long target areas,with significant short-term efficacy and safety.

Key words: whole spine, multicenter, metastases, radiation therapy