Simultaneous integrated boost intensity-modulated radiotherapy for conserved breast: a comparative study on the dosimetric merits of photon and electron beams

Abstract

Objective To compare the dosimetric merits of photon beam and electron beam simultaneous integrated boost intensity modulated radiation therapy (SIB-IMRT) for conserved breast to explore the dose difference of photon and electron beam integrated boost for whole breast, ipsilateral lung and the heart. Methods Ten patients with breast cancer treated by conserving-breast operation were selected to study, the region marked by silver clips with extended margin of 10 mm was defined as gross target volume (GTV) and the whole breast was delineated as the clinical target volume (CTV). Photon beam and electron beam integrated boost planning were designed respectively for every patient using ADAC Pinnacle~3 planning system and the dosimetric merits were compared. Results There were not significant difference for dose uniformity and conformality between the plannings with photon beam and electron beam integrated boost. There were not significant difference for the volumes of the ipsilateral lung received ≥20 Gy and equal or more than the prescribed dose for GTV between different planning, but the volume of the lung received equal or more than prescribed dose for CTV in electron beam planning was significantly higher than that in photon beam planning(P=0.014). There were not significant difference for the volumes of the heart received ≥30 Gy and equal or more than prescribed dose for CTV in photon and electron beam planning. Conclusions There is not significant difference for most of the dosimetric parameters in photon beam and electron beam integrated boost planning, but the volume of the ipsilateral lung received equal or more than prescribed dose in electron planning is significantly higher than that in photon beam planning.;