@article{MaierKnottMaerzetal., author = {Maier, Johannes and Knott, Bernadette and M{\"a}rz, Manuel and L{\"o}schel, Rainer and K{\"o}lbl, Oliver and Dobler, Barbara}, title = {Simultaneous integrated boost (SIB) radiation therapy of right sided breast cancer with and without flattening filter - A treatment planning study}, series = {Radiation oncology}, volume = {11}, journal = {Radiation oncology}, publisher = {BMC, Part of Springer Nature}, doi = {10.1186/s13014-016-0687-6}, abstract = {Background: The aim of the study was to compare the two irradiation modes with (FF) and without flattening filter (FFF) for three different treatment techniques for simultaneous integrated boost radiation therapy of patients with right sided breast cancer. Methods: An Elekta Synergy linac with Agility collimating device is used to simulate the treatment of 10 patients. Six plans were generated in Monaco 5.0 for each patient treating the whole breast and a simultaneous integrated boost (SIB) volume: intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and a tangential arc VMAT (tVMAT), each with and without flattening filter. Plan quality was assessed considering target coverage, sparing of the contralateral breast, the lungs, the heart and the normal tissue. All plans were verified by a 2D-ionisation-chamber-array and delivery times were measured and compared. The Wilcoxon test was used for statistical analysis with a significance level of 0.05. Results: Significantly best target coverage and homogeneity was achieved using VMAT FFF with V95\% = (98.7 +/- 0.8) \% and HI = (8.2 +/- 0.9) \% for the SIB and V95\% = (98.3 +/- 0.7) \% for the PTV, whereas tVMAT showed significantly lowest doses to the contralateral organs at risk with a D-mean of (0.7 +/- 0.1) Gy for the contralateral lung, (1.0 +/- 0.2) Gy for the contralateral breast and (1.4 +/- 0.2) Gy for the heart. All plans passed the gamma evaluation with a mean passing rate of (99.2 +/- 0.8) \%. Delivery times were significantly reduced for VMAT and tVMAT but increased for IMRT, when FFF was used. Lowest delivery times were observed for tVMAT FFF with (1:20 +/- 0:07) min. Conclusion: Balancing target coverage, OAR sparing and delivery time, VMAT FFF and tVMAT FFF are considered the preferable of the investigated treatment options in simultaneous integrated boost irradiation of right sided breast cancer for the combination of an Elekta Synergy linac with Agility and the treatment planning system Monaco 5.0.}, language = {en} } @article{DoblerMaierKnottetal., author = {Dobler, Barbara and Maier, Johannes and Knott, Bernadette and Maerz, Manuel and L{\"o}schel, Rainer and K{\"o}lbl, Oliver}, title = {Second Cancer Risk after simultaneous integrated boost radiation therapy of right sided breast cancer with and without flattening filter}, series = {Strahlentherapie und Onkologie}, volume = {192}, journal = {Strahlentherapie und Onkologie}, number = {10}, publisher = {Springer Nature}, address = {Heidelberg}, doi = {10.1007/s00066-016-1025-5}, pages = {687 -- 695}, abstract = {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.}, language = {en} }