Chaikh Abdulhamid, Docquière Nicolas, Bondiau Pierre-Yves, Balosso Jacques
Department of Radiation Oncology and Medical Physics, University Hospital of Grenoble, Grenoble, France; ; France HADRON National Research Infrastructure, Lyon, France.
Department of Radiation Oncology and Medical Physics, University Hospital of Grenoble, Grenoble, France.
Transl Lung Cancer Res. 2016 Dec;5(6):673-680. doi: 10.21037/tlcr.2016.11.04.
The equivalent uniform dose (EUD) radiobiological model can be applied for lung cancer treatment plans to estimate the tumor control probability (TCP) and the normal tissue complication probability (NTCP) using different dose calculation models. Then, based on the different calculated doses, the quality adjusted life years (QALY) score can be assessed versus the uncomplicated tumor control probability (UTCP) concept in order to predict the overall outcome of the different treatment plans.
Nine lung cancer cases were included in this study. For the each patient, two treatments plans were generated. The doses were calculated respectively from pencil beam model, as pencil beam convolution (PBC) turning on 1D density correction with Modified Batho's (MB) method, and point kernel model as anisotropic analytical algorithm (AAA) using exactly the same prescribed dose, normalized to 100% at isocentre point inside the target and beam arrangements. The radiotherapy outcomes and QALY were compared. The bootstrap method was used to improve the 95% confidence intervals (95% CI) estimation. Wilcoxon paired test was used to calculate P value.
Compared to AAA considered as more realistic, the PBC overestimated the TCP while underestimating NTCP, P<0.05. Thus the UTCP and the QALY score were also overestimated.
To correlate measured QALY's obtained from the follow-up of the patients with calculated QALY from DVH metrics, the more accurate dose calculation models should be first integrated in clinical use. Second, clinically measured outcomes are necessary to tune the parameters of the NTCP model used to link the treatment outcome with the QALY. Only after these two steps, the comparison and the ranking of different radiotherapy plans would be possible, avoiding over/under estimation of QALY and any other clinic-biological estimates.
等效均匀剂量（EUD）放射生物学模型可应用于肺癌治疗计划，以使用不同的剂量计算模型来估计肿瘤控制概率（TCP）和正常组织并发症概率（NTCP）。然后，基于不同的计算剂量，可以相对于无并发症肿瘤控制概率（UTCP）概念评估质量调整生命年（QALY）评分，以预测不同治疗计划的总体结果。
本研究纳入9例肺癌病例。对于每位患者，生成两个治疗计划。剂量分别根据笔形束模型计算，即笔形束卷积（PBC）并使用修正的巴托（MB）方法开启一维密度校正，以及点核模型，即各向异性解析算法（AAA），使用完全相同的处方剂量，在靶区内等中心点和射束布置处归一化为100%。比较放疗结果和QALY。采用自助法改进95%置信区间（95%CI）估计。使用Wilcoxon配对检验计算P值。
与被认为更符合实际情况的AAA相比，PBC高估了TCP，同时低估了NTCP，P<0.05。因此，UTCP和QALY评分也被高估。
为了将患者随访获得的实测QALY与DVH指标计算的QALY相关联，应首先将更准确的剂量计算模型纳入临床应用。其次，临床实测结果对于调整用于将治疗结果与QALY联系起来的NTCP模型参数是必要的。只有在这两个步骤之后，才有可能对不同的放疗计划进行比较和排序，避免对QALY和任何其他临床生物学估计的高估或低估。
