Dosimetric comparison of the heart substructures with IMRT and VMAT techniques in left breast radiotherapy: the effect of deep inspiratory breath-hold

Background: this study aimed to compare the doses received by the four chambers and vascular structures of the heart during adjuvant radiotherapy (rt) after left breast -conserving surgery (bcs) using intensity-modulated rt (imrt) and volumetricmodulated arc therapy (vmat) techniques. material and methods: simulation images were taken of 14 patients who underwent left bcs with both free-breathing (fb) and deep inspiration breath-hold (dibh) techniques. left breast rt was planned with both imrt and vmat. planned target volumes 50 and 60, homogeneity index, conformity index, and monitor unit values, as well as radiation doses received by organs at risk, were compared. results: in imrt compared to vmat, in the heart (dmean, v10, v2 ) and heart substructures (left ventricle [v5] , right ventricle [dmean], right atrium [dmean, dmax], left atrium [dmean, v5], right coronary artery [rca; dmean, dmax], left artery coronary main [lacm; dmean], and left circumflex artery [lcxa; dmean, dmax]), significant dose reductions were observed. when fb and dibh results were compared, in the dibh technique, the heart (dmean, v25, v10, v2) and heart substructures (left ventricle [dmean, dmax, v23, v5], right ventricle [dmean, dmax], right atrium [dmean, dmax], left atrium [dmean, dmax], left anterior descending artery [dmean, dmax, v20], rca [dmax], lacm [dmean], and lcxa [dmean, dmax]), doses were significantly decreased. conclusion: in rt of patients with left bcs, significant dose reductions occurred in the lung, heart, and almost all substructures of the heart using dibh compared to fb.