Department of Radiation Oncology, University Hospital Zürich, Switzerland.
Radiother Oncol. 2011 Oct;101(1):226-32. doi: 10.1016/j.radonc.2011.05.072. Epub 2011 Jul 4.
To investigate if there is a statistically significant difference in cancer cell survival using a high dose per pulse flattening filter-free (FFF) beam compared to a standard flattened beam.
To validate the radiobiological effect of the flattened and FFF beam, two glioblastoma cell lines were treated with either 5 or 10 Gy using different dose rates. Dose verification was performed and colony formation assays were carried out. To compare the predictability of our data, radiobiological models were included.
The results presented here demonstrate that irradiation of glioblastoma cell lines using the FFF beam is more efficient in reducing clonogenic cell survival than the standard flattened beam, an effect which becomes more significant the higher the single dose. Interestingly, in our experimental setting, the radiobiological effect of the FFF beam is dependent on dose per pulse rather than on delivery time. The used radiobiological models are able to describe the observed dose rate dependency between 6 and 24 Gy/min.
The results presented here show that dose per pulse might become a crucial factor which influences cancer cell survival. Using high dose rates, currently used radiobiological models as well as molecular mechanisms involved urgently need to be re-examined.
研究使用高剂量脉冲平坦过滤自由（FFF）束与标准平坦束相比，癌细胞存活率是否存在统计学显著差异。
为了验证平坦束和 FFF 束的放射生物学效应，使用不同剂量率分别用 5 或 10Gy 对两种脑胶质瘤细胞系进行处理。进行剂量验证和集落形成测定。为了比较数据的可预测性，纳入了放射生物学模型。
本文介绍的结果表明，与标准平坦束相比，使用 FFF 束照射脑胶质瘤细胞系可更有效地降低集落形成细胞的存活率，而且随着单次剂量的增加，这种效果变得更加显著。有趣的是，在我们的实验设置中，FFF 束的放射生物学效应取决于每个脉冲的剂量，而不是输送时间。所使用的放射生物学模型能够描述在 6 至 24Gy/min 之间观察到的剂量率依赖性。
本文介绍的结果表明，每个脉冲的剂量可能成为影响癌细胞存活率的关键因素。使用高剂量率时，目前使用的放射生物学模型以及涉及的分子机制急需重新检查。
