医科达磁共振加速器初步临床实践

目的 初步分析医科达磁共振加速器(Unity MR-Linac)摆位精度及流程时间等相关问题。方法 回顾Unity MR-Linac实验入组患者共 14例,统计分析所有分次的治疗时间(包括摆位、扫描、重新制订计划和出束时间)和各个方向的摆位误差。随机选取常规加速器使用一体架固定的患者 11例,统计摆位误差。成组t检验两组摆位误差的差异。结果 Unity组患者在左右、进出、升降方向的摆位误差分别为(-0.15±0.30)、(0.02±0.57)、(-0.10±0.28) cm;总体平均治疗时间为36.87min,其中摆位平均时长5.40min,扫描平均时长7.48min,自适应计划平均时长7.46min,出束平均时长9.48min。常规加速器组患者在上述3个方向的误差分别为(0.05±0.25)、(-0.01±0.25)、(-0.03±0.23) cm。两组摆位误差在左右方向不同(P<0.001),进出和升降方向相近(P=0.061、0.374)。结论 除左右方向外,在无激光灯情况下患者的摆位误差与常规加速器摆位误差相近。应用流程在顺利情况下治疗时间也在患者承受范围之内。MR引导放疗应用前景广阔,流程上需要优化。

Preliminary clinical practice of Elekta Unity MR-linac

Objective To summarize the experience of ELEKTA Unity MR-linac in clinical application in our hospital and analyze the positioning accuracy, process time and other related issues. Methods A total of 14 patients enrolled in the Unity MR-Linac study were reviewed. All treatment time (including positioning, scanning, replanning, and beam discharge) and setup errors in 3directions were statistically analyzed. 11 patients with conventional accelerators using the multifunctional immobilization system (MIS) were randomly selected to make statistical analysis of the setup errors, and the differences between the Unity group and the conventional accelerators using the MIS were compared using t-test. Results In the Unity group, the setup errors in X,Y and Z directions were (-0.15±0.30) cm,(0.02±0.57) cm and (-0.10±0.28) cm, respectively. The average treatment time was 36.87minutes. The average positioning time was 5.40minutes. The mean scan time was 7.48minutes, the mean adaptive plan time was 7.46minutes, and the mean beam time was 9.48minutes. In the conventional accelerator group, the setup errors were (0.05±0.25) cm,(-0.01±0.25) cm and (-0.03±0.23) cm, respectively. The results of the setup errors of patients fixed with MIS showed that there were significant differences in the left and right directions (P<0.001), while there were no significant differences in the Y and Z directions (P=0.061 and 0.374) between two groups. Conclusions Except in the X direction, there is no significant difference in setup errors between the Unity and conventional accelerator groups in the condition of laser-free system. Under smooth circumstances, the treatment time by using ATP (adapt to position) workflow will also be within the range of tolerance of the patients. Magnetic-guided radiotherapy has a promising application prospect, whereas the procedure needs to be optimized.