A COMPARATIVE DOSIMETRIC STUDY OF LEFT SIDED BREAST CANCER AFTER BREAST CONSERVING SURGERY WITH 3D-CRT AND VMAT

Purpose: This paper aims to compare dosimetric differences based between three-dimensional conformal radiotherapy (3D-CRT), and volumetric modulated arc therapy(VMAT) techniques of radiotherapy plans for postoperative left breast cancer after breast conserving surgery. Materials and Methods: Nineteen patients with left breast cancer who had received breast conserving surgery without nodal involvement. Two separate treatment plans with an identical isocenter were created to each patient: 3D radiotherapy plan with 2 tangent isocentric beams with field-in-field technique andVMAT plan with Two duplicate sets of partial arcs. Results: The VMAT plan showed superior to PTV dose conformity index (CI), homogeneity index (HI), protection of the ipsilateral lung, and heart compared with 3D plan. However, it increases significantly dose to the contralateral breast with D mean which were 0.1±0.003 Gy and 5.31±1.04 Gy, respectively. Conclusion: VMAT greatly decreases the radiation doses delivered to the OAR with maintained therapeutic efficacy.However, further studies evaluating the clinical outcome of treatments are needed to proof the clinical value of this radiation technique.