The effect of linear accelerator mechanical and dose errors on the validation pass rate of volume arc intensity modulated radiotherapy plan for brain gliomas
The effect of linear accelerator mechanical and dose errors on the validation pass rate of volume arc intensity modulated radiotherapy plan for brain gliomas
王猛 1孙维凯 1王凡 1王馨
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作者信息
1. 同济大学附属同济医院放射治疗科，上海 200065
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摘要
目的 研究加速器机械和剂量误差对胶质瘤容积旋转弧形调强放疗（VMAT）计划剂量验证γ通过率的影响。 方法 选取2022年7月至2023年7月同济大学附属同济医院放射治疗科20例高级别脑胶质瘤病例的VMAT，使用医科达直线加速器和PTW调强验证工具进行验证，统计通过率。利用软件修改这些VMAT计划的某些参数模拟加速器运行过程中可能出现的机械和剂量误差，获得改造后的计划。使用上述设备重新对改造后的VMAT计划进行验证，统计通过率，与原计划的通过率进行比较分析。 结果 机械误差[机架的角度、准直器到位误差和多叶准直器（MLC）不同类型的到位误差]和辐射剂量误差（MU）对胶质瘤VMAT计划的γ通过率均有影响，进一步的研究表明MLC的误差比机架的旋转角度、准直器的相对位置偏离和MU对绝对剂量验证γ通过率有更加明显的影响。 结论 针对胶质瘤患者的VMAT计划，应根据检测仪器的性能采用合适的通过率指标，并尽可能使用绝对剂量验证。 Objective To investigate the effects of accelerator mechanical and dose errors on the dose validation pass rate of the glioma Volumetric Modulated Arc Therapy (VMAT) plan. Methods The VMAT plan of 20 cases of high-grade glioma was selected and verified with Elekta linear accelerator and PTW intensity modulation verification tool, and the passing rate was counted. Use software Matlab to modify some parameters of these VMAT plans to simulate mechanical and dose errors that may occur during accelerator operation, and recalculate the dose. Use the above equipment again to verify the modified VMAT plan, calculate its pass rate, and compare and analyze it with the original plan's pass rate. Result Both mechanical errors (frame rotation angle, collimator positioning error, multi-leaf collimator (MLC) positioning error of different types) and dose errors (MU) have an impact on the validation pass rate of the glioma VMAT plan. Further research has shown that MLC errors have a more significant impact on the absolute dose validation pass rate than frame rotation angle errors, collimator errors and MU errors. Conclusion For the glioma VMAT plan, in order to improve the validation pass rate of the program, it is necessary to separately implement stricter quality control on MLC. Futhermore, appropriate pass rate indicators should be used based on the performance of the testing equipment, absolute dose validation should be used as much as possible.
Abstract
Objective To investigate the effects of accelerator mechanical and dose errors on the dose validation pass rate of the glioma Volumetric Modulated Arc Therapy (VMAT) plan. Methods The VMAT plan of 20 cases of high-grade glioma was selected and verified with Elekta linear accelerator and PTW intensity modulation verification tool, and the passing rate was counted. Use software Matlab to modify some parameters of these VMAT plans to simulate mechanical and dose errors that may occur during accelerator operation, and recalculate the dose. Use the above equipment again to verify the modified VMAT plan, calculate its pass rate, and compare and analyze it with the original plan's pass rate. Result Both mechanical errors (frame rotation angle, collimator positioning error, multi-leaf collimator (MLC) positioning error of different types) and dose errors (MU) have an impact on the validation pass rate of the glioma VMAT plan. Further research has shown that MLC errors have a more significant impact on the absolute dose validation pass rate than frame rotation angle errors, collimator errors and MU errors. Conclusion For the glioma VMAT plan, in order to improve the validation pass rate of the program, it is necessary to separately implement stricter quality control on MLC. Futhermore, appropriate pass rate indicators should be used based on the performance of the testing equipment, absolute dose validation should be used as much as possible.
关键词
机械和剂量误差/胶质瘤/容积旋转弧形调强放疗/通过率
Key words
Mechanical and dose errors/Glioma/Volume arc intensity modulated radiotherapy/Pass rate
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