A Comprehensive Dosimetric Analysis of Inverse Planned Intensity Modulated Radiation Therapy and Multistatic Fields Technique for Left Breast Radiotherapy

Moon, Sung Kwon; Youn, Seon Min

Abstract

PURPOSE
This aim of this study is to analyze the dosimetric difference between intensity-modulated radiation therapy (IMRT) using 3 or 5 beams and MSF in the radiotherapy of the left breast.
MATERIALS AND METHODS
We performed a comparative analysis of two radiotherapy modalities that can achieve improved dose homogeneity. First is the multistatic fields technique that simultaneously uses both major and minor irradiation fields. The other is IMRT, which employs 3 or 5 beams using a fixed multileaf collimator. We designed treatment plans for 16 early left breast cancer patients who had taken breast conservation surgery and radiotherapy, and analyzed them from a dosimetric standpoint.
RESULTS
For the mean values of V95 and dose homogeneity index, no statistically significant difference was observed among the three therapies. Extreme hot spots receiving over 110% of the prescribed dose were not found in any of the three methods. A Tukey test performed on IMRT showed a significantly larger increase in exposure dose to the ipsilateral lung and heart than multistatic fields technique (MSF) in the low-dose area, but in the high-dose area, MSF showed a slight increase.
CONCLUSION
In order to improve dose homogeneity, the application of MSF, which can be easily planned and applied more widely, is considered an optimal alternative to IMRT for radiotherapy of early left breast cancer.