{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T15:09:41Z","timestamp":1779894581650,"version":"3.53.1"},"reference-count":43,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T00:00:00Z","timestamp":1779840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Background: Recent improvements, such as flattening filter-free (FFF) beams, enable the delivery of treatments at higher dose rates and in shorter times. However, the biological influence still remains uncertain. Here, we examined how dose rate and dose per pulse influence responses to FFF beams compared with flattened beams in cancer cells with different radiosensitivities. Methods: A549 (lung, high \u03b1\/\u03b2) and MCF-7 (breast, low \u03b1\/\u03b2) cells were irradiated using VMAT (6 MV FF, 6 and 10 MV FFF; 600\u20132400 MU\/min; 5\u201320 Gy). Cell viability was assessed by the WST-1 assay, and reproductive survival by clonogenic assay. Results: The responses differed by cell type and dose, with A549 exhibiting restricted sensitivity, demonstrating more pronounced effects at 10 Gy, while MCF-7 displayed greater responsiveness at 5\u201310 Gy under elevated dose rates. At 20 Gy, differences were reduced. Metabolic readouts did not consistently match clonogenic survival. Conclusions: Overall, FFF effects appear cell-specific, and the suggestion is that clinical translation should be guided by tumor-specific radiosensitivity rather than an assumption of universal benefit.<\/jats:p>","DOI":"10.3390\/life16060903","type":"journal-article","created":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T14:36:56Z","timestamp":1779892616000},"page":"903","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Radiobiological Effect of Flattening Filter Free (FFF) Beam Delivery Parameters on A549 and MCF-7 Cell Survival: An In Vitro Study"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6423-8956","authenticated-orcid":false,"given":"Cemile","family":"Ceylan","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology, Medicalpark Istanbul Oncology Hospital, 34180 Istanbul, T\u00fcrkiye"},{"name":"Department of Medical Physics, Yeditepe University, 34755 Istanbul, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kamil Can","family":"K\u0131l\u0131\u00e7","sequence":"additional","affiliation":[{"name":"Department of Stem Cell, Institute of Health Sciences, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Center for Stem Cell and Gene Therapies Research and Practice, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Department of Histology and Embryology, Faculty of Medicine, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahmet","family":"\u00d6zt\u00fcrk","sequence":"additional","affiliation":[{"name":"Department of Stem Cell, Institute of Health Sciences, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Center for Stem Cell and Gene Therapies Research and Practice, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Department of Histology and Embryology, Faculty of Medicine, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Canan","family":"\u00d6zt\u00fcrk","sequence":"additional","affiliation":[{"name":"Department of Stem Cell, Institute of Health Sciences, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Center for Stem Cell and Gene Therapies Research and Practice, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yusufhan","family":"Yaz\u0131r","sequence":"additional","affiliation":[{"name":"Department of Stem Cell, Institute of Health Sciences, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Center for Stem Cell and Gene Therapies Research and Practice, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"},{"name":"Department of Histology and Embryology, Faculty of Medicine, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maksut G\u00f6rkem","family":"Aksu","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Faculty of Medicine, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00d6zcan","family":"G\u00fcndo\u011fdu","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Faculty of Technology, Kocaeli University, 41380 Kocaeli, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"259","DOI":"10.2217\/cns.13.11","article-title":"Stereotactic body radiotherapy: A new paradigm in the management of spinal metastases","volume":"2","author":"Husain","year":"2013","journal-title":"CNS Oncol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"265","DOI":"10.3857\/roj.2015.33.4.265","article-title":"Radiobiological mechanisms of stereotactic body radiation therapy and stereotactic radiation surgery","volume":"33","author":"Kim","year":"2015","journal-title":"Radiat. 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