Halcyon加速器在乳腺癌保乳术后放射治疗中的临床应用

Clinical application of radiotherapy for breast cancer after breast-conserving surgery on Halcyon accelerator

目的探究在Halcyon直线加速器上使用调强适形放射治疗(IMRT)和容积旋转调强放射治疗(VMAT)进行乳腺癌保乳术后放射治疗的临床应用。方法选择乳腺癌保乳术后放射治疗患者25例,年龄36~61岁,平均年龄50.9岁;左侧乳腺癌15例,右侧乳腺癌10例;肿瘤分期均为T1~T2、N0、M0。计划设计均在Eclipse计划系统上,每例患者分别采用IMRT和VMAT进行计划设计。对两类计划的主要剂量学参数、剂量分布、γ通过率和照射时间进行比较。结果所有计划均可临床使用,两组计划靶区D_(95%)、平均剂量D_(mean)差异较小(P>0.05),靶区均匀性指数(HI)(IMRT组0.06±0.01 vs VMAT组0.06±0.01),差异无统计学意义(P>0.05),适形性指数(CI)(IMRT组0.85±0.03 vs VMAT组0.92±0.02),差异有统计学意义(P<0.05)。IMRT组患侧肺V_(5)、V_(20)和平均剂量,心脏平均剂量,健侧肺V_(5)均低于VMAT组,差异具有统计学意义[患侧肺V_(5)(41.36±2.04)%vs(47.58±2.42)%、患侧肺V_(20)(15.04±2.90)%vs(16.35±1.97)%、患侧肺平均剂量(886.32±79.41)cGy vs(993.49±50.14)cGy、心脏平均剂量(209.23±98.12)cGy vs(277.60±83.18)cGy、健侧肺V_(5)(2.10±1.35)%vs(14.06±8.62)%。P<0.05]。VMAT组γ通过率优于IMRT组,差异有统计学意义[3 mm/3%(99.72±0.20)%vs(99.38±0.37)%;2 mm/2%(97.22±1.05)%vs(96.99±0.91)%。P<0.05]。IMRT组照射时间(2.08±0.27)min,VMAT组照射时间(0.87±0.04)min,VMAT组节省超过55%照射时间,差异有统计学意义(P<0.05)。结论使用Halcyon直线加速器进行保乳术后放射治疗,IMRT计划和VMAT计划均能满足临床治疗需求,采用VMAT技术会提高靶区的剂量分布,明显提高计划执行效率。

Objective To explore the clinical application of intensity modulated radiation therapy(IMRT)and volumetric modulated arc therapy(VMAT)on Halcyon linear accelerator for radiotherapy after breast-conserving surgery in patients with breast cancer.Methods A total of 25 female patients with breast cancer performed radiotherapy after breast-conserving surgery were enrolled,which aged 36-61 years old with mean age of 50.9 years old;15 cases of left breast cancer and 10 of right breast cancer;the tumor stages were T1-T2,N0 and M0.The plans were designed on Eclipse planning system,the IMRT and VMAT were both used in each patient.The main dosimetric parameters,dose distribution,γpass rate and irradiation time of 2 plans were compared.Results All plans were available for clinical,there was no significant difference in D_(95%)and mean dose D_(mean)between 2 groups(P>0.05).The target homogeneity index(HI)of 2 groups(IMRT group 0.06±0.01 vs VMAT group 0.06±0.01)(P>0.05)were barely the same.In addition,the difference conformity index(CI)of IMRT group(0.85±0.03)was statistically significantly lower than VMAT group(0.92±0.02)(P<0.05).The V_(5),V_(20)and D_(mean)of affected lung,heart D_(mean),and healthy lung V_(5)in IMRT group were statistically significantly lower than those in VMAT group[affected lung V_(5)(41.36±2.04)%vs(47.58±2.42)%,affected lung V_(20)(15.04±2.90)%vs(16.35±1.97)%,affected lung D_(mean)(886.32±79.41)cGy vs(993.49±50.14)cGy,heart D_(mean)(209.23±98.12)cGy vs(277.60±83.18)cGy,healthy lung V_(5)(2.10±1.35)%vs(14.06±8.62)%.P<0.05].Theγpass rate of VMAT group was better than that of IMRT group,and the difference was statistically significant[3 mm/3%(99.72±0.20)%vs(99.38±0.37)%;2 mm/2%(97.22±1.05)%vs(96.99±0.91)%.P<0.05].The irradiation time of IMRT group was(2.08±0.27)minutes,and irradiation time of VMAT group was(0.87±0.04)minutes,the VMAT group saved more than 55%of irradiation time,and the difference was statistically significant(P<0.05).Conclusion It is demonstrated that both IMRT plan and VMAT plan could meet the clinical requirements when Halcyon linear accelerator is used for radiotherapy after breast-conserving surgery,and VMAT technology could improve dose distribution of target area and significantly improve efficiency of plan execution.