The impact of the radiotherapy technique in sparing the heart substructures in central tumor irradiation in lung cancer

Abstract Introduction: In thoracic radiotherapy (RT), heart sparing is very essential, as the high cardiac dose is associated with poor survival in patients with locally advanced non-small-cell lung cancer (NSCLC). The study aims to determine the doses exposed to heart substructures and coronary arteries by different RT techniques in central tumor irradiation in lung cancer. Methods: Twenty patients with NSCLC, irradiated between January 2018 and December 2020 in our department, were included in this study. Patients whose primary tumor was centrally located in the left lung were selected. The heart substructures [left atrium, right atrium (RA), left ventricle, and right ventricle] and coronary arteries (left main, left anterior descending, circumflex, and right coronary arteries) were delineated by the same physician. The doses of 60 Gy external RT were prescribed in 30 fractions using three-dimensional conformal radiotherapy (3D-CRT), static intensity-modulated radiotherapy (s-IMRT), and dynamic intensity-modulated radiotherapy (d-IMRT) techniques in all patients. The obtaining plans using three different techniques were compared. Results: The d-IMRT plans were statistically the best optimal plan for planning target volume (PTV) [D mean ( p = 0 04), D max ( p < 0 0001), V 95 ( p < 0 0001), V 107 ( p < 0 0001), CI ( p < 0 0001) and HI ( p < 0 0001)]. The s-IMRT plans were significantly superior to 3D-CRT plans for PTV. RA D max and V 45 were not different between the three techniques [D max ( p = 0 148) and V 45 ( p = 0 12)]. The d-IMRT technique was significantly better in other heart substructures and coronary arteries. Conclusions: Compared to 3D-CRT and s-IMRT techniques, the d-IMRT technique provided the best protection in all heart substructures except for a few parameters (RA D max and V 45 doses).