en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: The radiobiological effect of high dose rate FFF beams on the DU-145 cells was investigated with SBRT plans which have >10 Gy. Methods and Materials: To compare the radiobiological effect on DU-145 cell line four experiments designed: (1) the constant dose rate of 6 MV and 6 MV FFF with increased dose per pulse (2) the effect of dose per pulse while increasing instantaneous dose rate for 6 MV and 6 MV FFF, (3) the effect of increased average dose rate for 6 MV FFF and (4) the effect of protracted treatment time and modulation of 6 MV FFF beams. The survival fraction was counted with WST. Results: FF and FFF for 6 MV with same dose rate and treatment time has no effect on cell survival. Significant differences was observed on survival which were irradiated with 6 MV 600 MU/min and 6 MV FFF 1400 MU/min (p=0.024). There was no difference between 6 MV FFF 600 MU/min and 6 MV FFF 1400 MU/min for 10 Gy. The significant survival difference obtained for 20 Gy. The survival percentages for both 10 Gy and 20 Gy with Cyberknife were obtained higher than FFF. Conclusion: Our in-vitro study presented here show that higher dose rate and reduced treatment time might become a crucial factor for SBRT especially which has >10 Gy fraction dose.</div> Flattening filter free, Cell survival, Radiosurgery, Radiobiology 879 889 http://ijrr.com/browse.php?a_code=A-10-1-878&slc_lang=en&sid=1 C. Ceylan cemile.ceylan@istanbulonko.com 7900319475328460019694 7900319475328460019694 Yes Center for Stem Cell and Gene Therapies Research and Practice, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey A. Öztürk 7900319475328460019695 7900319475328460019695 No Center for Stem Cell and Gene Therapies Research and Practice, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey G. Güngör 7900319475328460019696 7900319475328460019696 No Department of Radiation Oncology, Acibadem University, Istanbul, Turkey A.U. Karabey 7900319475328460019697 7900319475328460019697 No Department of Radiation Oncology, Kocaeli University, Kocaeli, Turkey S. Şahin 7900319475328460019698 7900319475328460019698 No Vocational School of Health Services, Fenerbahce University, Istanbul, Turkey G. Duruksu 7900319475328460019699 7900319475328460019699 No Center for Stem Cell and Gene Therapies Research and Practice, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey Y. Yazır 7900319475328460019700 7900319475328460019700 No Center for Stem Cell and Gene Therapies Research and Practice, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey G. Aksu 7900319475328460019701 7900319475328460019701 No Department of Radiation Oncology, Kocaeli University, Kocaeli, Turkey Ö. Gündoğdu 7900319475328460019702 7900319475328460019702 No Deparment of Biomedical Engineering, Kocaeli Univetsity, Kocaeli, Turkey