Clinical application of radiotherapy for breast cancer after breast-conserving surgery on Halcyon accelerator
Objective To explore the clinical application of intensity modulated radiation therapy(IMRT)and volumetric mod ulated 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,NO and MO.The plans were designed on Eclipse planning system,the IMRT and VMAT were both used in each patient.The main dosimetric parameters,dose distribution,γ pass rate and irradi-ation time of 2 plans were compared.Results All plans were available for clinical,there was no significant difference in D95％and mean dose Dmean 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 V5,V20 and Dmean of affected lung,heart Dmean,and healthy lung V5 in IMRT group were statistically significantly lower than those in VMAT group[affected lung V5(41.36±2.04)％vs(47.58±2.42)％,affected lung V20(15.04±2.90)％vs(16.35±1.97)％,affected lung Dmean(886.32±79.41)cGy vs(993.49±50.14)cGy,heart Dmean(209.23±98.12)cGy vs(277.60±83.18)cGy,healthy lung V5(2.10±1.35)％vs(14.06±8.62)％.P＜0.05].The γ pass 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 demonstrat-ed 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 sig-nificantly improve efficiency of plan execution.
eclipseHalcyonradiotherapy after breast-conserving surgeryintensity modulated radiation therapydose distributionsirradiation time
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