SU-GG-T-149: A Dosimetric Comparison of Conventional Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Radiotherapy for Left-Breast Cancer after Breast-Conserving Surgery

Abstract

Objective To compare the dosimetric differences of forward intensity‐modulated radiotherapy,inverse intensity‐modulated radiotherapy and volumetric modulated arc radiotherapy(IMAT) for left‐breast cancer after breast‐conserving surgery. Methods Ten patients with left‐breast cancer receiving breast‐conserving surgery were enrolled in the study.Three treatment techniques including forward intensity‐modulated radiotherapy(f‐IMRT), inverse intensity‐modulated radiotherapy(IMRT) and volumetric modulated arc radiotherapy(RA) were designed for each patient. The dose distribution in the target,the dose to the organs at risk,total MU and delivery time were compared.Results All three plans met the clinical requirement.RA plans showed the best conformity in target and IMRT plans were better than f‐IMRT plans.F‐IMRT plans showed the best homogeneity in target,no statistically significant differences were observed between RA and IMRT plans.For the V5 and V10 in left lung,f‐IMRT and RA plans were statistically significant lower than IMRT plans.and f‐IMRT plans showed the lowest value. For the V20 and V30 in left lung, the IMRT and RA plans were statistically significant lower than f‐IMRT plans.and the RA plans showed the lowest value.The maximum dose and V40 in heart were lowest for the RA plans.and RA plans showed statistically significant lower for the mean dose in heart versus IMRT plans.The V5, V10 and the mean dose in right lung,and the mean dose to the contra‐lateral breast were lowest for f‐IMRT plans.No statistically significant differences were observed in these indexes for IMRT versus RA plans.The maximum dose to the contra‐lateral breast was lowest for RA plans.For the number of MU.IMRT and f‐IMRT plans showed the highest and lowest value respectively. The RA plans reduced the delivery time by 84.6%and 88.23% compared to f‐IMRT and IMRT plans.Conclusions Compared to f‐IMRT and IMRT plans,the RA plans showed a better conformity in target,reduced the irradiated volume of high dose region in the left lung and heart as well as significantly decreased the delivery time.