comparison of lung and contralateral scattered breast dose between field-in-field and wedge techniques in patients with early breast cancer

Purpose: this study aims to evaluate the dosimetric result of the field-in-field (fif) plans compared with tangential wedged beams (twb) plans for whole breast radiotherapy of patients.materials and methods: in this survey, we entered fifty patients with breast-conserving surgery and postoperative whole-breast radiotherapy. fif and a twb plan were made for each patient to compare dosimetric outcomes.results: the homogeneity index (hi) and conformity index (ci) were specified for the evaluation of planning target volume (ptv). the mean dose of the ipsilateral lung and contra-lateral breast for the evaluation of organs at risk dose were used. the fif plans had significantly lower hi (p < 0.01) and ci (p < 0.01) than those of the twb plans. it means in the dosimetric comparisons of the ptv, the fif plans were better than the twb plans. the v10lung (31.152vs. 32.72%, p < 0.01), v20lung (25.6064vs. 26.6%, p < 0.01) v30lung (17.4% vs. 18.4%, p < 0.01) were lower with the fif plans compared with those of the twb plans, with statistical significance. the fif plans had a lower mean dose for the lung than those of twb plans (1225.48 vs. 1670.32 cgy) but no statistical significance (p=0.06). the mean dose in the contra-lateral of the breast in fif plans was lower than in twb plans (61.666 vs. 163.45 cgy), with statistical significance (p < 0.01).conclusion: the fif plans increased the dose homogeneity, and conformity of the target volume for the whole-breast irradiation compared with the twb plans contralateral breast. moreover, the doses of organs at risk (ipsilateral lung and contralateral breast) were reduced with fif plans.