Influence of respiratory movement during post mastectomy radiotherapy on targets and heart for breast cancer

Background/aim: This study aimed to compare the dosimetric consequences of respiratory movement in volumetric-modulated arc therapy (VMAT) and three-dimensional conformal radiation therapy (3D-CRT) during postmastectomy radiation therapy, including internal mammary nodes (IMNs). Materials and methods: Respiratory motion was implemented to a phantom using a dynamic device. The plans were delivered during cranial-caudal and ventral-dorsal movement in 5-mm (R05) and 10-mm (R10) amplitudes. Results: At the IMN, the dose errors were –2.8% (R05) and –6.2% (R10) for 3D-CRT and –4.9% (R05) and –8.5% (R10) for VMAT. The dose errors in chest wall were –.5% (R05) and –6.0% (R10) for 3D-CRT and –1.9% (R05) and –5.3% (R10) for VMAT. The left anterior descending doses showed significantly small absolute values. The gamma pass rates of VMAT were higher than those of 3D-CRT. Conclusions: The benefit of VMAT technique in dose distribution was maintained, except in occasional instances of large breathing motion.