Rojo-Santiago Jesús, Habraken Steven J M, Unipan Mirko, Both Stefan, Bosmans Geert, Perkó Zoltán, Korevaar Erik, Hoogeman Mischa S
Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, the Netherlands; HollandPTC, Delft, the Netherlands.
Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, the Netherlands; HollandPTC, Delft, the Netherlands.
Radiother Oncol. 2024 Oct;199:110441. doi: 10.1016/j.radonc.2024.110441. Epub 2024 Jul 26.
In the Netherlands, 2 protocols have been standardized for PT among the 3 proton centers: a robustness evaluation (RE) to ensure adequate CTV dose and a model-based selection (MBS) approach for IMPT patient-selection. This multi-institutional study investigates (i) inter-patient and inter-center variation of target dose from the RE protocol and (ii) the robustness of the MBS protocol against treatment errors for a cohort of head-and-neck cancer (HNC) patients treated in the 3 Dutch proton centers.
Clinical treatment plans of 100 HNC patients were evaluated. Polynomial Chaos Expansion (PCE) was used to perform a comprehensive robustness evaluation per plan, enabling the probabilistic evaluation of 100,000 complete fractionated treatments. PCE allowed to derive scenario distributions of clinically relevant dosimetric parameters to assess CTV dose (D/D, based on a prior photon plan calibration) and tumour control probabilities (TCP) as well as the evaluation of the dose to OARs and normal tissue complication probabilities (NTCP) per center.
For the CTV, doses from the RE protocol were consistent with the clinical plan evaluation metrics used in the 3 centers. For the CTV, D were consistent with the clinical plan evaluation metrics at center 1 and 2 while, for center 3, a reduction of 1 GyRBE was found on average. This difference did not impact modelled TCP at center 3. Differences between expected and nominal NTCP were below 0.3 percentage point for most patients.
The standardization of the RE and MBS protocol lead to comparable results in terms of TCP and the NTCPs. Still, significant inter-patient and inter-center variation in dosimetric parameters remained due to clinical practice differences at each institution. The MBS approach is a robust protocol to qualify patients for PT.
在荷兰，3个质子治疗中心针对调强质子治疗（PT）制定了2种标准化方案：一种是用于确保靶区适形调强放疗（IMRT）剂量充足的稳健性评估（RE）方案，另一种是用于IMPT患者选择的基于模型的选择（MBS）方法。这项多机构研究调查了（i）RE方案中患者间和中心间靶区剂量的差异，以及（ii）在荷兰3个质子治疗中心接受治疗的一组头颈癌（HNC）患者中，MBS方案针对治疗误差的稳健性。
对100例HNC患者的临床治疗计划进行了评估。采用多项式混沌展开（PCE）对每个计划进行全面的稳健性评估，从而能够对100,000次完整的分次治疗进行概率评估。PCE允许得出临床相关剂量学参数的情景分布，以评估靶区适形调强放疗（CTV）剂量（基于先前光子计划校准的D/D）和肿瘤控制概率（TCP），以及每个中心对危及器官（OAR）的剂量和正常组织并发症概率（NTCP）的评估。
对于CTV，RE方案的剂量与3个中心使用的临床计划评估指标一致。对于CTV，D在中心1和中心2与临床计划评估指标一致，而对于中心3，平均发现剂量降低了1 GyRBE。这种差异并未影响中心3的模拟TCP。大多数患者预期和标称NTCP之间的差异低于0.3个百分点。
RE和MBS方案的标准化在TCP和NTCP方面产生了可比的结果。尽管如此，由于每个机构的临床实践差异，剂量学参数在患者间和中心间仍存在显著差异。MBS方法是一种用于确定患者是否适合PT的稳健方案。
