Objective.不同的放射治疗(RT)策略,例如,常规分馏RT(CFRT),高分割RT(HFRT),立体定向体RT(SBRT),自适应RT,和再照射通常用于治疗头颈部(HN)癌症。组合和/或比较这些策略需要计算生物有效剂量(BED)。这项研究的目的是开发一种实用的过程来估计器官特异性放射生物学模型参数,该参数可用于HN癌症的个性化RT计划中的BED计算。方法。CFRT的临床剂量约束数据,HFRT和SBRT用于5个危险器官(OAR),即脊髓,脑干,臂丛神经,光学通路,从文献中获得的食管进行分析。这些临床数据对应于特定的终点。线性二次(LQ)和线性-二次线性(LQ-L)模型用于拟合这些临床数据并提取相关模型参数(α/β比,gamma/alpha,DTandBED)来自等有效曲线。使用获得的参数计算2Gy分数(EQD2)中等效物理剂量方面的剂量约束。主要结果。LQ-L和LQ模型很好地拟合了从CFRT到SBRT的临床数据,其中LQ-L代表了对大多数OAR的更好拟合。LQ-L(LQ)的α/β值为2.72(2.11)Gy,0.55(0.30)Gy,2.82(2.90)Gy,6.57(3.86)Gy,5.38(4.71)Gy,剂量约束EQD2为55.91(54.90)Gy,57.35(56.79)Gy,57.54(56.35)Gy,脊髓60.13(59.72)Gy和65.66(64.50)Gy,光学通路,脑干,臂丛神经,和食道,分别。另外两个LQ-L参数为5.24Gy,5.09Gy,7.00Gy,5.23Gy,和6.16Gy,γ/α分别为7.91、34.02、8.67、5.62和4.95。意义。开发了一种实用的方法来从临床数据中提取器官特异性放射生物学模型参数。所获得的参数可以用于基于生物的辐射规划,诸如计算不同分次方案的剂量约束。
Objective.Different radiation therapy (RT) strategies, e.g. conventional fractionation RT (CFRT), hypofractionation RT (HFRT), stereotactic body RT (SBRT), adaptive RT, and re-irradiation are often used to treat head and neck (HN) cancers. Combining and/or comparing these strategies requires calculating biological effective dose (BED). The purpose of this study is to develop a practical process to estimate organ-specific radiobiologic model parameters that may be used for BED calculations in individualized RT planning for HN cancers.Approach.Clinical dose constraint data for CFRT, HFRT and SBRT for 5 organs at risk (OARs) namely spinal cord, brainstem, brachial plexus, optic pathway, and esophagus obtained from literature were analyzed. These clinical data correspond to a particular endpoint. The linear-quadratic (LQ) and linear-quadratic-linear (LQ-L) models were used to fit these clinical data and extract relevant model parameters (alpha/beta ratio, gamma/alpha,dTand BED) from the iso-effective curve. The dose constraints in terms of equivalent physical dose in 2 Gy-fraction (EQD2) were calculated using the obtained parameters.Main results.The LQ-L and LQ models fitted clinical data well from the CFRT to SBRT with the LQ-L representing a better fit for most of the OARs. The alpha/beta values for LQ-L (LQ) were found to be 2.72 (2.11) Gy, 0.55 (0.30) Gy, 2.82 (2.90) Gy, 6.57 (3.86) Gy, 5.38 (4.71) Gy, and the dose constraint EQD2 were 55.91 (54.90) Gy, 57.35 (56.79) Gy, 57.54 (56.35) Gy, 60.13 (59.72) Gy and 65.66 (64.50) Gy for spinal cord, optic pathway, brainstem, brachial plexus, and esophagus, respectively. Additional two LQ-L parametersdTwere 5.24 Gy, 5.09 Gy, 7.00 Gy, 5.23 Gy, and 6.16 Gy, and gamma/alpha were 7.91, 34.02, 8.67, 5.62 and 4.95.Significance.A practical process was developed to extract organ-specific radiobiological model parameters from clinical data. The obtained parameters can be used for biologically based radiation planning such as calculating dose constraints of different fractionation regimens.