ArticleStrahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al]2015
Impact of flattening-filter-free radiation on the clonogenic survival of astrocytic cell lines.
Article in Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al], 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
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Who cites it
3 citing papers in PubMed.
- The Radiobiological Effect of Flattening Filter Free (FFF) Beam Delivery Parameters on A549 and MCF-7 Cell Survival: An In Vitro Study.Life (Basel, Switzerland) · 2026Article
- Effect of plan complexity on the dosimetry, delivery accuracy, and interplay effect in lung VMAT SBRT with 6 MV FFF beam.Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al] · 2022Article
- Automatically gated image-guided breath-hold IMRT is a fast, precise, and dosimetrically robust treatment for lung cancer patients.Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al] · 2016Article
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Authors and funding
11 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
background and purposeFlattening-filter-free (FFF) beams are increasingly used in radiotherapy as delivery times can be substantially reduced. However, the relative biologic effectiveness (RBE) of FFF may be increased relative to conventional flattened (FLAT) beams due to differences in energy spectra. Therefore, we investigated the effects of FFF and FLAT beams on the clonogenic survival of astrocytoma cells. MATERIAL AND
methodsThree cell lines (U251, U251-MGMT, and U87) were irradiated with 6-MV and 10-MV X-rays from a linear accelerator in FFF- or FLAT-beam modes at dose rates in the range of 0.5-24 Gy/min. The surviving fraction (SF) as function of dose (2-12 Gy) was determined by the colony formation assay and fitted by the linear-quadratic model. For both beams (FFF or FLAT), the cells were pelleted in conical 15-ml centrifuge tubes and irradiated at 2-cm depth in a 1 × 1-cm(2) area on the central axis of a 30 × 30-cm(2) field. Dosimetry was performed with a 0.3-cm(3) rigid ionization chamber. RBE was determined for FFF versus FLAT irradiation.
resultsThe RBE of FFF at 7.3-11.3 Gy was 1.027 ± 0.013 and 1.063 ± 0.018 relative to FLAT beams for 6- and 10-MV beams, respectively, and was only significantly higher than 1 for 10 MV. Significantly increased survival rates were seen for lower dose rates (0.5 Gy/min FLAT vs. 5 Gy/min FLAT) at higher doses (11.9 Gy), while no differences were seen at dose rates ≥ 1.4 Gy/min (1.4 Gy/min FFF vs. 14 Gy/min FFF and 2.4 Gy/min FFF vs. 24 Gy/min FFF).
conclusionsFFF beams showed only a slightly increased RBE relative to FLAT beams in this experimental set-up, which is unlikely to result in clinically relevant differences in outcome.
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