SEQUENTIAL VOLUMETRIC MODULATED ARC THERAPY (VMAT) BOOST IN HYBRID PLAN WITH TANGENTIAL BEAMS FOR WHOLE BREAST TREATMENT: A DOSIMETRIC STUDY
Publication Date : 24/02/2022
Purpose Whole breast radiation therapy (WBRT) with a boost to the tumor bed following conservative primary surgery in women with breast cancer (BC) plays a central role in reducing local recurrences and mortality. Volumetric modulated arc therapy (VMAT) technique has been shown to allow better dose conformation with low dose levels to organs at risk (OARs), compared to static fields three-dimensional Conformal Radiotherapy (3D-CRT). Aim of this study was to evaluate the feasibility and dosimetric advantages of sequential boost (SB), administered with VMAT technique in hybrid plans with tangential beams for whole breast treatment. Material and methods BC patients undergoing adjuvant RT from June to October 2020 were selected. ESTRO guidelines for the Clinical Target Volume (CTV) delineation were used. Total delivered dose was 60-66 Gy; 50 Gy in 2 Gy daily fractions for whole breast and 10-16 in 2 Gy daily fractions Gy to tumor bed was 10-16 Gy in 2 Gy daily fractions. Results The analysis included 31 patients with BC treated with adjuvant RT following conservative surgery. Hybrid treatment plans characterized by a 3D-CRT plan using tangential mediolateral and lateromedial fields for the irradiation of the whole breast Planning Target Volume (PTV) and a sequential VMAT plan with 2 coplanar arches for boost PTV irradiation were generated. As regarding to organs at risks (OARs), contralateral breast, ipsi- and contro-lateral lung and heart costraints values were analysed. Conclusions In the frame BC RT, this dosimetric study showed that hybrid plans performed with 3D-CRT and VMAT techniques are feasible in terms of dosimetric outcomes.
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