Dosimetric difference between VMAT and dMLC-IMRT after breast-conserving surgery for left-sided breast cancer / 医疗卫生装备

ABSTRACT

Objective To investigate the dosimetric difference between volume modulated arc therapy(VMAT)and dynamic multi-leaf collimator intensity modulated radiation therapy(dMLC-IMRT)after breast-conserving surgery for left-sided breast cancer so as to optimize the treatment plan for the patient.Methods The clinical data of 15 patients admitted to the radiothe-rapy department of some hospital after breast-conserving surgery for left-sided breast cancer were selected retrospectively.Three groups of plans were designed for each patient,including continue volume modulated arc therapy(cVMAT),tangent volume modulated arc therapy(tVMAT)and dMLC-IMRT plans,and then compared in terms of the dosimetric parameters of the tumor target areas and organs at risk.SPSS 25.0 software was used for statistical analysis.Results The three groups had the dose distribution of the tumor target areas meet clinical requirements,which had significant differences between the values of D2,Dmean,conformity index(CI)and homogeneity index(HI),while the difference between the numbers of monitor units were not statistically significant.The dMLC-IMRT group had higher D2 value while lowerDmeanthan the cVMAT and tVMAT groups;for CI the cVMAT behaved the best in the three groups,followed by the tVMAT group.In the low-dose region,the cVMAT and tVMAT groups had larger illuminated volumes of the affected lung than the dMLC-IMRT group;the tVMAT group had the smallest illuminated volume of heart in the three groups,and the cVMAT group had the illuminated volume of heart slightly higher than that of the dMLC-IMRT group.In the high-dose region,the cVMAT and tVMAT groups had smaller illuminated volumes of the affected lung than the dMLC-IMRT group,and the illuminated volume of the affected lung of the tVMAT group was larger than that of the cVAMT group;the dMLC-IMAT group had the largest illuminated volume of heart in the three groups,and the differences between the tVMAT and cVMAT groups were not statistically significant.Conclusion In the design of intensity-modulated radiotherapy plans after breast-conserving surgery for left-sided breast cancer,VMAT behaves better than dMLC-IMRT in conformability to the tumor target area and protection of heart and lung at risk.[Chinese Medical Equipment Journal,2023,44(9)59-63]