Abstract
Purpose:This study aimed to compare estimates of secondary cancer risks using five radiotherapy modalities to treat breast cancer: intensity‐modulated radiotherapy (IMRT), 3‐dimensional conformal radiation therapy (3D‐CRT), field‐in‐field forward‐planned intensity‐modulated radiation (FinF), volumetric modulated arc therapy (VMAT), and TomoHDA (TOMO).Methods:Each of 10 selected breast patients was re‐planned with the five different modalities. The planning target volume (PTV) was defined as the contoured breast subtracted 5 mm from the skin, and lungs, heart, and contralateral breast were contoured as OARs. The prescription (Rx) was 50.4 Gy in 28 fractions, which covered 95% of the PTV. Dose constraints for the contralateral lung of volumes receiving 20 Gy and 10 Gy (V20Gy and V10Gy) were less than 20% and 40%, respectively, a maximum cord dose less than 45 Gy and for the rest. Qrgan equivalent doses (OEDs), dose characteristics, and lifetime attributable risks (LARs) were derived from dose‐volume histograms for in‐field regions and radio‐photoluminescence glass dosimeter (RPLGD) measurements for out‐of‐field regions.Results:TOMO had a better target dose distribution than 3D‐CRT and FinF. OEDs for TOMO were similar to those of 3D‐CRT in in‐field region but increased as distance from the field boundary increased. LARs of the lung and contralateral breast were highest for VMAT, followed by IMRT, FinF, 3D‐CRT, and TOMO. IMRT and VMAT had a 40–50% lower in V20Gy than 3D‐CRT.Conclusion:Our results indicate that TOMO provides comparable plan quality for breast cancer radiotherapy compared to IMRT/VMAT, and, at the same time, the lowest cancer risk in in‐field regions among all studied treatment modalities. Therefore TOMO could be a better alternative treatment modality than 3D‐CRT for breast cancer patients.
Published Version
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