Application of the linear-quadratic model to combined modality radiotherapy
Application of the linear-quadratic model to combined modality radiotherapy
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DOI：
10.1016/j.ijrobp.2003.12.031
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发表时间：
2004-05-01
影响因子：
7
通讯作者：
Flux, GD
中科院分区：
文献类型：
--
作者：
Bodey, RK;Evans, PM;Flux, GD
目的：采用生物有效剂量（BED）建立了由靶向放射性核素治疗（TRT）和单独外照射治疗（EBT）组成的联合模式放射治疗（CMRT）的剂量测定方法。然而，同时提供的两种疗法可能会影响治疗的放射生物学效应的治疗之间的相互作用，这种情况已被建模，以评估可能的后果，这种regiment.Methods和Materials：一个一般形式的线性二次模型与剂量延长因子被施加到EBT和TRT的同时交付。计算了模态内和模态间效应对总BED的贡献，并改变参数值以确定模态间贡献可能最显著的条件。一个泊松模型的肿瘤控制概率（TCP）被用来评估的预测效果的同时交付的治疗outcome.Results：在一般情况下，在广泛的参数值，在CMRT的影响是小的，增加总BED交付给肿瘤约1%，并产生一个可以忽略不计的TCP增加。如果从两种疗法中接受高剂量，则在正常组织中的协同效应可能更大，在一般情况下，多模态项使总BED增加约6%，在脊髓缓慢修复的情况下增加约18%。当α/β = 1.2戈伊、α = 0.026戈伊、mu = 0.36 h（-1）和N-0 = 138克隆原时，预测EBT和I-125粒子治疗前列腺之间具有显著的协同效应，TCP从约0.5增加到0.6。在大多数临床条件下，这两种疗法的相对时间递送不太可能显著影响细胞水平上对肿瘤的总体放射生物学效应。然而，协同效应在正常组织和具有低α/β和α值的肿瘤中可能更显著。(C)2004年爱思唯尔公司
Purpose: Methods of performing dosimetry for a combined modality radiotherapy (CMRT) consisting of a targeted radionuclide therapy (TRT) and separately delivered external beam therapy (EBT) have been established using the biologically effective dose (BED). However, a concurrent delivery of the two therapies may influence the radiobiologic effect of the treatment resulting from interaction between the therapies, and this situation has been modeled to assess the likely consequences of this regime.Methods and Materials: A general form of the linear-quadratic model with a dose protraction factor was applied to concurrent delivery of EBT and TRT. Contributions to total BED from intra- and intermodality effects were calculated, and parameter values varied to determine conditions under which the intermodality contributions were likely to be most significant. A Poisson model of tumor control probability (TCP) was used to assess the predicted effect of concurrent delivery on treatment outcome.Results: In general, over a wide range of parameter values, the effect of intermodality interactions in CMRT is small, increasing total BED delivered to tumor by approximately 1%, and producing a negligible increase in TCP. Synergistic effects could be greater in normal tissues if high doses were received from both therapies, with intermodality terms increasing total BED delivered by approximately 6% in the general case, and by approximately 18% for the case of slow repair in the spinal cord. A significant synergistic effect was predicted between EBT and I-125 seed therapy of the prostate when values of alpha/beta = 1.2 Gy, alpha = 0.026 Gy, mu = 0.36 h(-1) and N-0 = 138 clonogens were used, with TCP increasing from approximately 0.5 to 0.6.Conclusions: Under most clinical conditions, the relative temporal delivery of these two therapies is unlikely to significantly influence the overall radiobiologic effect to tumor at the cellular level. Synergistic effects may, however, be more significant in normal tissues and for tumors with low values of alpha/beta and alpha. (C) 2004 Elsevier Inc.