Dosimetric analysis of intensity-modulated radiotherapy and three-dimensional conformal radiotherapy for chest wall irradiation in breast cancer patients

Background: For chest wall irradiation in breast cancer patients, three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) have made tremendous changes in treatment delivery. Purpose: The purpose of this study is to compare the dosimetric parameters in IMRT and 3DCRT plans. Materials and methods: IMRT and 3DCRT plans were generated for 25 randomly selected postmastectomy breast cancer patients. The prescribed dose (PD) was 50 Gray (Gy) in 25 fractions (#) at the rate of 2 Gy/# with 5#/week. Dose volume histogram was evaluated for planning target volume (PTV) coverage and dose to organs at risk (OARs). All the dosimetric parameters were compared using unpaired student's t-test. Results: PTV coverage was significantly better in IMRT, although the 90% of PTV was well covered by 90% of PD in all plans by both the techniques. Homogeneity index and conformity index were better in IMRT. V-5 Gy and D-mean of contralateral lung, contralateral breast and heart (right side chest wall cases) were found to be lesser in 3DCRT compared with that in IMRT. However, there was no significant difference in V-20 Gy of ipsilateral lung and V-25 Gy of heart (left side chest wall cases) in all the plans by both the techniques. Conclusion: Adequate target coverage was achieved by both the techniques, however, dose to OARs were lesser in 3DCRT plans as compared with that in IMRT plans. Thus, it can be concluded that 3DCRT is as efficient as IMRT for the chest wall irradiation.