Comparison of six irradiation techniques for delivering hypofractionated whole-breast radiotherapy with a simultaneous integrated boost after breast-conserving surgery

Background: to compare the following techniques for hypofractionatedwhole-breast irradiation (wbi) with simultaneous integrated boost (sib) after breast-conserving surgery (bcs): three-dimensional conformal radiation therapy pluselectron boost (3dcrt-eb), intensity-modulated radiation therapy (imrt) plus eb(imrt-eb), field-in-field imrt plus eb (fif-imrt-eb), fif-imrt plus imrt boost(fif-imrt-ib), imrt plus imrt boost (imrt-ib), and volumetric-modulated arctherapy (vmat) plus vmat boost (vmat-vb). materials and methods: twentypatients with left breast cancer were enrolled. the prescribed dose was 40.05 gy in15 fractions to the whole breast and an sib to the tumor bed of 3.2 gy/fraction(total, 48 gy). target-volume coverage, dose-conformity index, homogeneity index(hi), doses to organs at risk (oar), and costs were compared. results: fif-imrt-ebperformed the best, while fif-imrt-ib, imrt-ib, and vmat-vb performed theworst. the mean dose to the planning target volume for breast evaluation(ptv eval-breast) was significantly lower for imrt-eb and fif-imrt-eb thanfor the other plans. for both ptv eval-breast and ptv eval-boost, vmat-vbhad the lowest target-volume coverage for 95% of the prescription dose andthe highest target-volume coverage for >105% of the prescription dose.among the six plans, vmat-vb had the best hi for ptv eval-boost and thehighest doses to all oar, except the coronary artery. plans with ebs had lowermean doses for the contralateral lung and contralateral breast than planswith imrt boosts. fif-imrt-eb had a low cost; plans with imrt boosts hadthe highest costs. conclusion: fif-imrt-eb may be the most suitable irradiationtechnique for hypofractionated wbi with sib after bcs.