Department of Radiation Oncology, Halifax Health, Daytona Beach, Florida 32114, USA.
Med Phys. 2013 Aug;40(8):081716. doi: 10.1118/1.4812432.
To investigate the effect of radiation protraction on biologically effective dose (BED) in the case when dose per fraction is significantly greater than the standard dose of 2 Gy.
By using the modified linear-quadratic model with monoexponential repair, the authors investigate the effect of long treatment times combined with dose escalation.
The dependences of the protraction factor and the corresponding BED on fraction time were determined for different doses per fraction typical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). In the calculations, the authors consider changes in the BED to the normal tissue under the condition of fixed BED to the target.
The obtained results demonstrate that simultaneous increase in fraction time and dose per fraction can be beneficial for SRS and SBRT because of the related decrease in BED to normal structures while BED to the target is fixed.
当每分次剂量显著大于标准剂量 2 Gy 时，研究放射分割对生物有效剂量（BED）的影响。
通过使用具有单指数修复的改良线性二次模型，作者研究了长治疗时间与剂量递增相结合的效果。
针对立体定向放射外科（SRS）和立体定向体部放射治疗（SBRT）中典型的每分次剂量，确定了分割因子和相应 BED 与分次时间的依赖性。在计算中，作者考虑了在固定靶区 BED 的情况下，正常组织 BED 变化的情况。
所得结果表明，由于正常结构的 BED 相关下降，同时增加分次时间和每分次剂量可能对 SRS 和 SBRT 有益，而靶区的 BED 是固定的。
