TY - JOUR A1 - Dobler, Barbara A1 - Maier, Johannes A1 - Knott, Bernadette A1 - Maerz, Manuel A1 - Löschel, Rainer A1 - Kölbl, Oliver T1 - Second Cancer Risk after simultaneous integrated boost radiation therapy of right sided breast cancer with and without flattening filter T2 - Strahlentherapie und Onkologie N2 - Background The aim of this study was to investigate if the flattening filter free mode (FFF) of a linear accelerator reduces the excess absolute risk (EAR) for second cancer as compared to the flat beam mode (FF) in simultaneous integrated boost (SIB) radiation therapy of right-sided breast cancer. Patients and methods Six plans were generated treating the whole breast to 50.4 Gy and a SIB volume to 63 Gy on CT data of 10 patients: intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and a tangential arc VMAT (tVMAT), each with flattening filter and without. The EAR was calculated for the contralateral breast and the lungs from dose-volume histograms (DVH) based on the linear-exponential, the plateau, and the full mechanistic dose-response model. Peripheral low-dose measurements were performed to compare the EAR in more distant regions as the thyroids and the uterus. Results FFF reduces the EAR significantly in the contralateral and peripheral organs for tVMAT and in the peripheral organs for VMAT. No reduction was found for IMRT. The lowest EAR for the contralateral breast and lung was achieved with tVMAT FFF, reducing the EAR by 25 % and 29 % as compared to tVMAT FF, and by 44 % to 58 % as compared to VMAT and IMRT in both irradiation modes. tVMAT FFF showed also the lowest peripheral dose corresponding to the lowest EAR in the thyroids and the uterus. Conclusion The use of FFF mode allows reducing the EAR significantly when tVMAT is used as the treatment technique. When second cancer risk is a major concern, tVMAT FFF is considered the preferred treatment option in SIB irradiation of right-sided breast cancer. KW - 3D-CRT KW - Breast Cancer KW - CONTRALATERAL BREAST KW - DOSES RELEVANT KW - flattening filter free KW - HODGKIN COHORTS KW - IMRT KW - INDUCTION KW - JAPANESE A-BOMB KW - Peripheral Dose KW - PREDICTED RISK KW - Radiotherapy KW - Second Cancer Risk KW - VMAT Y1 - 2016 UR - https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/3205 VL - 192 IS - 10 SP - 687 EP - 695 PB - Springer Nature CY - Heidelberg ER -