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Establishment of a dose-conversion model for use in high-dose-per-fraction radiotherapy

高剂量分次放疗剂量转换模型的建立

基本信息

批准号：
20591501
负责人：
SHIBAMOTO Yuta
金额：
$ 2.41万
依托单位：
Nagoya City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20591501/
关键词：
定位照射放射線治療生物学 LQモデル分割照射線量換算

项目摘要

The reliability of the linear-quadratic (LQ) formalism in assessing biological equivalence between single high and hypofractionated radiation doses were investigated using single cells, spheroids and murine tumors. Single doses of 2-26Gy and 2-5 fractions of 4-12Gy were used. The α/β ratio was obtained from the cell survival curves, and using it and the LQ formalism, equivalent single doses for the hypofractionated doses were calculated. They were then compared with actually-determined equivalent single doses for the hypofractionated doses. In all experiments, equivalent single doses for hypofractionated doses calculated from the LQ formalism were lower than the actually-measured biologically-equivalent single doses by 10-40%. Conversion of hypofractionated radiation doses to single doses using the LQ formalism underestimated the effect of hypofractionated radiation. In direct comparison of the 2- to 5-fraction schedules, respective dose-response curves almost overlapped when cell survival was plotted against actual radiation doses. However, the curves tended to shift downwards by increasing the fraction number when cell survival was plotted against biologically effective doses (BED) calculated using an α/β ratio for in vitro EMT6 cells. Thus, BED was inappropriate. Using the multi-target model, the compatibility improved at high doses, but still dose conversion was not perfect. Other biological models are now being investigated.

使用单细胞、球体和小鼠肿瘤研究了线性二次（LQ）形式主义在评估单次高分次和低分次辐射剂量之间生物等效性方面的可靠性。单次剂量2- 26 Gy，4- 12 Gy分次2-5次。从细胞存活曲线中获得α/β比值，并使用该比值和LQ形式，计算低分次剂量的等效单次剂量。然后将其与实际确定的低分次剂量的等效单次剂量进行比较。在所有实验中，根据LQ形式计算的大剂量的等效单次剂量比实际测量的生物等效单次剂量低10- 40%。使用LQ公式将大分割放射剂量转换为单次剂量低估了大分割放射的效果。在直接比较的2至5部分的时间表，各自的剂量-反应曲线几乎重叠时，细胞存活率对实际辐射剂量绘制。然而，当细胞存活率与使用体外EMT 6细胞的α/β比计算的生物有效剂量（BED）作图时，曲线倾向于通过增加分数而向下移动。因此，床是不合适的。使用多靶点模型，在高剂量下相容性得到改善，但剂量转换仍不完美。目前正在研究其他生物模型。