Retrospective investogation of dosimetric comparasion of hybrid (conformal and tangential intensity modulated radiotherapy), field in field conformal radiotherapy techniques in breast cancer

It is aimed to compare the dosimetric results of Field in Field Conformal Radiotherapy (FinF-3DCRT), Tangential Intensity Modulated Radiotherapy (tIMRT), and Hybrid Tangential Intensity Modulated Radiotherapy (Hybrid-IMRT) in the radiotherapy techniques after breast conserving surgical (BCS) for early stage left–sided patients. In this study, different treatment techniques were planned for CT images of ten patients with early stage left breast cancer, FiF - 3BKRT, tYART and hybrid (MONACO TPS). Hybrid plans were generated for each study case by combining different dose proportions of FinF-3DCRT and tIMRT plans including: 20% FinF – 3DCRT /80% tIMRT, 40% FinF – 3DCRT 3DCRT/60% tIMRT, 60% FinF – 3DCRT /40% tIMRT, 80% FinF – 3DCRT /20% tIMRT. We used two opposed tangential fields including 3-segments for FinF –3DCRT plans. tYART plans were planned with two tangential fields gantry angle is same in FinF – 3DCRT. In the simulation plans created, the target volume, left lung, heart, LAD (left descending artery), opposite breast and healthy tissue doses, as well as the Conformity Index (CI), Homogeneity Index (HI) were evaluated. As a result, t-YART technique has obtained a more homogeneous and conformal dose distribution than other techniques. The techniques tYART and Hybrid techniques are superior to other techniques in terms of low dose radiation in healthy tissues. Keywords: Radiotherapy, Breast Cancer, FiF-3DCRT, tIMRT, Hybrid - IMRT