IMRT for the breast: a comparison of tangential planning techniques

Three intensity-modulated tangential beam radiotherapy plan types for breast cancer treatment were evaluated based on PTV homogeneity index (HI) and equivalent uniform dose (EUD), heart V30 and EUD, whole lung V20 and EUD, and typical planning time compared to conventional 2D plans. 20 early-stage breast cancer patients were CT-scanned in the supine position, and tangential field extent, gantry and collimator angles were chosen. Four treatment plans were created for each patient: conventional, dynamically wedged plan based on the dose distribution on the central axial slice; forward planned IMRT; surface compensated plan created using an Eclipse tool and hybrid IMRT plan combining open and inverse-optimized fields. All three IMRT planning techniques represent significant improvement in PTV HI and EUD compared to conventional plans. Among the IMRT plans, the hybrid IMRT plan produced the best HI. IMRT lowered heart V30 and lung V20, but no significant differences in heart or lung EUD were detected between IMRT techniques. The IMRT technique with the shortest planning time was the compensated plan, followed by the hybrid IMRT. IMRT planning provides dosimetric benefits in breast cancer patients. The selection of the most appropriate IMRT technique must include careful consideration of the resources available.