Dosimetric Evaluation of the Field in Field Technique for Large Breast Cancer Irradiation

The aim of this work is using multi segmented conformal radiotherapy, field in field (FIF) for large breast cancer treatment, the dose coverage of the planning target volume (PTV) and evaluation the radiation load on the organs at risk (OARs). Ten patients with large breasts of mean PTV was 1489 ± 335 Cm³ were included. Many parameters were used in the dose evaluations in the PTV OARs volume including ipsi lateral lung, heart, and the contralateral breast, Dose homogeneity index (DHI) and conformity index (PITV). The FIF technique for all patients improved the homogeneity and conformity of the PTV, where the mean values of maximum dose of the PTV was 107%, the volumes over the prescription dose in irradiated volumes received very low doses. For each dosimetry of the organs at risk, the FIF technique reduced the dose that these organs received. It could be concluded that the FIF technique provided a better dose distribution in the PTV, reduced the doses in the OARs and improved the homogeneity and conformity of the planning volume