Usefulness of EZFluence software for radiotherapy planning of breast cancer treatment

This study compared the EZFluence planning technique for irradiation of the breast with commonly used Field-in-Field (FiF) technique by analyzing the dose uniformity, the dose to the lung, heart, and other organs at risk, the total Monitor Unit (MU), and the time spent for planning. Two different 3-dimensional conformal dose plans were created for 20 breast cancer patients. Six patients were treated to a dose of 5000 cGy in 25 fractions and 14 were treated to a dose of 4256 cGy in 16 fractions. Average breast volume was 800 cc (range 128 to 1892 cc). For the FiF technique, the planner manually created between 2 to 4 subfields per gantry angle and sequentially blocked the 115% and 110% isodose line until a homogenous dose distribution was achieved. For the EZFluence technique, the planner implemented the EZFluence script that created an optimal fluence pattern, which was then imported into Eclipse where dose was calculated. Both techniques were optimized to make sure 95% of the breast planning target volume (PTV) received at least 95% of the prescribed dose. Compared to FiF technique, the plans produced by using EZFluence technique, showed the MU increased by 36.9% (p = 0.0002), whereas the planning time decreased significantly by 84.6% (p = 0.00001). The mean heart dose and the relative volume of the heart receiving ≥ 30 Gy (V30) were similar for both techniques. The mean lung dose and the relative volume of lung receiving ≥ 20 Gy (V20) were also comparable between 2 techniques. The contralateral breast mean dose and its relative volume receiving ≥ 3 Gy (V3) and ≥10 Gy (V10) were equally spared and avoided. EZFluence planning technique yielded a 4.6% (p = 0.04) reduction in PTV receiving 105% of the prescribed dose (V105) for the large breast with separation > 22 cm and PTV volume > 650 cc. The EZFluence planning technique yielded the overall comparable or improved dosimetry while significantly reducing planning time.