What new dose distribution statistics may be included in the optimization of dose distribution in radiotherapy for post-mastectomy patients

Abstract

Introduction. The main aim of this study was to evaluate the doses delivered to heart substructures and calculate normal tissue complication probability (NTCP) for the intensity modulation radiotherpy (IMRT) irradiated group of left-sided post-mastectomy patients. Material and methods. In this retrospective study for 30 randomly chosen breast cancer patients, the mean dose, V2, V4, V10, V20 and D2% in the heart substructures were evaluated. Results. The mean heart dose was 12.3 Gy, the mean left anterior descending artery (LAD) dose was 28.5 Gy. The average value of long-term cardiac mortality was 0.17%, pericarditis 0.0%, left ventricle perfusion defects 24.5% and LAD toxicity 0.2%. In the literature, for the IMRT technique for left-sided mastectomy patients, the mean heart dose ranged from 8.7–14.0 Gy and the V20 10.5–14%. Additional studies are needed to describe the cardiac toxicity. Conclusions. It is necessary to contour cardiac substructures for reliable assessment of the dose distribution, although the mean heart dose is simplification for modern radiotherapy techniques.