Halcyon 3.0双等中心调强放射治疗计划在左侧乳腺癌根治术后放射治疗中的可行性评估

Feasibility assessment of Halcyon 3.0 dual-isocenter IMRT plan in postoperative radiotherapy of radical mastectomy for left side of breast cancer

目的:评估基于Halcyon 3.0直线加速器设计的双等中心调强放射治疗(IMRT)计划在左侧乳腺癌根治术后放射治疗中的可行性。方法:选取2022年12月至2023年6月上海中医药大学附属曙光医院收治的左侧乳腺癌根治术后放射治疗患者16例,分别基于Halcyon 3.0直线加速器设计双等中心计划和Truebeam加速器设计常规单等中心计划,统计两种计划的靶区适形度(CI)、均匀性(HI)和危及器官受照剂量等剂量学参数,对比分析Halcyon 3.0双等中心计划的剂量学表现。使用ArcCHECK和Portal Dosimetry两种剂量验证工具评估Halcyon 3.0双等中心计划射束输送的精准性。结果:Halcyon双等中心计划和Truebeam单等中心计划具有相似的计划质量。靶区的CI、HI、2%靶区体积的受照剂量(D_(2%))及98%靶区体积的受照剂量(D_(98%))等剂量学参数差异均无统计学意义(P>0.05)。Halcyon 3.0双等中心计划的机器跳数相比于Truebeam单等中心计划平均机器跳数增加366 MU,但差异无统计学意义(P>0.05)。Halcyon 3.0双等中心计划对于危及器官的保护全面优于Truebeam单等中心计划,其中Halcyon 3.0双等中心计划和Truebeam单等中心计划的20 Gy剂量覆盖的左侧肺体积(V_(20))分别为(20.41±1.56)%和(24.88±2.95)%,差异具有统计学意义(t=6.413,P<0.05),其他危及器官剂量学参数差异无统计学意义(P>0.05)。剂量容差(DT)/距离一致性(DTA)设置为2%/2 mm时,Halcyon 3.0双等中心计划在ArcCHECK和Portal Dosimetry平台的验证γ通过率分别为97.6%~98.9%和98.1%~100%;DT/DTA设置为3%/3 mm时,Halcyon 3.0双等中心计划在ArcCHECK和Portal Dosimetry平台的验证γ通过率分别为99.1%~100%和99.7%~100%,Halcyon 3.0双等中心计划射束输送精度符合临床治疗验证标准。结论:Halcyon 3.0双等中心IMRT计划在左侧乳腺癌根治术后的放射治疗中具有较高的可行性。计划剂量输送精准性高,靶区剂量充分、均匀、适形度良好,同时能够较好地限制危及器官的受照剂量。

Objective:To assess the feasibility of the designed dual-isocenter IMRT plans based on Halcyon 3.0 linear accelerator in postoperative radiotherapy of radical mastectomy for left side of breast cancer.Methods:A total of sixteen patients received the postoperative radiotherapy of radical mastectomy for left side of breast cancer at Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine from December 2022 to June 2023 were retrospectively selected.The dual-isocenter plans based respectively on Halcyon 3.0 linear accelerator and Truebeam linear accelerator were designed,and the dosimetric parameters included conformity index(CI)values of target region,homogeneity index(HI)values and doses to organs at risk(OAR)of the two plans were calculated as statistic method.And then,the dosimetric performance of Halcyon 3.0 dual-isocenter plan was compared and analyzed.Utilizing two dose verification tools,ArcCHECK and Portal Dosimetry,to assess the precision of beam delivery of Halcyon 3.0 dual-isocenter plan.Results:The Halcyon dual-isocenter plan and the Truebeam single-isocenter plan had similar plan quality.There were not statistically significant differences(P>0.05)in dosimetric parameters such as CI,HI,exposure dose to 2%of the target volume(D_(2%))and exposure dose to 98%of the target volume(D_(98%)).Compared to the average monitor unit(MU)of Truebeam single-isocenter plan,the MU values of Halcyon 3.0 dual-isocenter plan increased by 366 MU,while the difference was not statistically significant(P>0.05).The Halcyon 3.0 dual-isocenter plan provided comprehensive protection for OAR,which was better than that of the Truebeam single-isocenter plan.The values of the left side of lung volume(V_(20))that were covered by 20 Gy dose of the Halcyon 3.0 dual-isocenter plan and the Truebeam single-isocenter plan were respectively 20.41%±1.56%and 24.88%±2.95%,and the difference was statistically significant(t=6.413,P<0.05).There were not significant differences in other OAR dosimetric parameters between the two kinds of plans(P>0.05).The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 97.6%-98.9%and 98.1%-100%when the ratio of dose tolerance(DT)to distance to agreement(DTA)was set at 2%/2 mm.The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 99.1%-100%and 99.7%-100%when DT/DTA was set at 3%/3 mm.The beam delivery precision of the Halcyon 3.0 dual-isocenter plan could meet verification standards of clinical treatments.Conclusion:The Halcyon 3.0 dual-isocenter IMRT plan demonstrates a higher feasibility in the postoperative radiotherapy of radical mastectomy for left side of breast cancer.The precision of dose delivery of plan is high,and the dose of target area is sufficient,uniform and favorable conformability.It can effectively limit the OAR exposure dose at the same time.