基于OCTAVIUS 4D的全中枢容积旋转调强放疗的接野部位剂量验证研究

Dose verification study for irradiation field overlap area of craniospinal irradiation using volumetric modulated arc therapy based on OCTAVIUS 4D verification equipment

目的:研究使用OCTAVIUS 4D验证设备对全中枢容积旋转调强放疗计划进行接野部位剂量验证的可行性和准确性,为全中枢容积旋转调强放疗计划接野部位剂量验证提供参考方法。方法:选取12例接受全中枢容积旋转调强接野放疗的患者,在治疗计划系统中分别建立头部中心、胸部中心、腹部中心验证计划和头胸射野衔接处、胸腹射野衔接处验证计划,通过OCTAVIUS 4D验证设备采集真实剂量。通过前后移床验证相邻中心射野衔接处的剂量分布。使用Verisoft 7.1软件分析全中枢容积旋转调强放疗单中心验证计划和射野衔接处验证计划的γ通过率。结果:阈值为10%时,头部、胸部和腹部中心计划在3 mm/3%标准下的γ通过率分别为(99.68±0.60)%、(99.63±0.52)%和(99.53±0.86)%,高于美国医学物理学家协会(American Association of Physicists in Medicine,AAPM)报告的关于治疗前患者计划剂量验证通过率的建议。相同条件下不同相邻中心射野衔接处的剂量分布略有差异,头胸接野部位的γ通过率略低于胸腹接野部位的γ通过率,且差异具有统计学意义(P<0.05)。阈值为10%时,横断面、冠状面、矢状面3 mm/3%标准下的γ通过率超过92%,5 mm/5%标准下的γ通过率则超过97%,均符合放疗计划治疗前的要求。结论:OCTAVIUS 4D验证设备可以用于全中枢容积旋转调强放疗计划剂量验证和接野部位的剂量验证,且接野部位的剂量验证通过率符合相关质控要求。

Objective To investigate the feasibility and accuracy of dose verification for irradiation field overlap area using the OCTAVIUS 4D verification device in the craniospinal irradiation(CSI)by volumetric modulated arc therapy(VMAT)plan,and to provide a reference method for the dose verification of the CSI VMAT plan.Methods Twelve patients undergoing CSI VMAT were selected.The verification plans were established for the head center,chest center,abdomen center and the head-chest and chest-abdomen overlap areas,and the actual doses were collected by the OCTAVIUS 4D validation device.The dose distributions at the irradiation field overlap areas were verified by moving the bed back and forth.Verisoft 7.1 software was used to analyze theγpass rates of the verification plans for the centers and overlap areas of CSI VMAT.Results At a threshold of 10%,theγpass rates for the head,chest and abdominal center plans under the 3 mm/3%criterion were(99.68±0.60)%,(99.63±0.52)%and(99.53±0.86)%respectively,which were higher than the recommended values for dose verification pass rate before treatment by American Association of Physicists in Medicine(AAPM).The dose distributions at different overlap areas had slightly differences at the same conditions,theγpass rate at the head-chest overlap area was slightly lower than that at the chest-abdomen overlap area,and the differences were statistically significant(P<0.05).At a threshold of 10%,theγpass rates in the transverse,coronal and sagittal planes exceeded 92%under the 3 mm/3%criterion and 97%under the 5 mm/5%criterion,all of which met the pre-treatment requirements of the radiotherapy plan.Conclusion The OCTAVIUS 4D validation device can be used for dose verification of CSI VMAT plans and overlap areas,and the dose verification pass rate of overlap areas meets relevant quality control requirements.