Department of Medical Physics, Aarhus University Hospital, Denmark.
Department of Radiation Oncology, University of Florida, Jacksonville, USA.
Radiother Oncol. 2020 Jan;142:140-146. doi: 10.1016/j.radonc.2019.08.002. Epub 2019 Aug 28.
Reducing radiation exposure to the temporal lobes could be beneficial to preserve cognitive function in paediatric brain tumour patients. The distribution of doses to brain substructures associated with cognition (BSCs) both within and outside of the temporal lobe have not been reported. The aim of this study was therefore to investigate temporal lobe sparing photon vs. proton therapy for paediatric suprasellar tumours.
Data from ten anonymized craniopharyngioma patients were used in this study. Temporal lobe sparing volumetric modulated arc therapy (VMAT) and pencil beam scanning (PBS) proton therapy plans were optimized to maintain consistent target metrics as in the delivered double scattering proton therapy (DSPT) plans. Thirty BSCs were delineated, including temporal lobe substructures (i.e. amygdala, hippocampus, entorhinal cortex). The dose/volume fractions to each BSC were analysed, and intelligence quotient (IQ) as well as memory scores were estimated to compare the different modalities.
The exposed volumes of the temporal lobes and their substructures were consistently reduced with PBS compared to DSPT and VMAT, e.g. the left hippocampus V10Gy from 100% (VMAT) or 41% (DSPT) to 5% with PBS (p = 0.002). Some of the ventricular substructures were better spared with VMAT compared to both proton modalities. The reduced doses to the temporal lobes achieved with PBS translated into improved predicted memory outcomes, but not for the estimated IQ.
The irradiated volumes of temporal lobe BSCs were consistently the lowest with PBS, whereas the model-based estimates of cognitive outcomes were less consistent.
降低颞叶的辐射暴露可能有益于保护儿科脑瘤患者的认知功能。尚未报道与认知相关的脑亚结构（BSC）的剂量分布，包括颞叶内和颞叶外的剂量分布。因此，本研究旨在探讨儿童颅咽管瘤的颞叶 spared 光子与质子治疗。
本研究使用了十名匿名颅咽管瘤患者的数据。颞叶 sparing 容积调强弧形治疗（VMAT）和笔形束扫描（PBS）质子治疗计划被优化，以保持与双散射质子治疗（DSPT）计划一致的靶区指标。勾画了 30 个 BSC，包括颞叶亚结构（如杏仁核、海马体、内嗅皮层）。分析了每个 BSC 的剂量/体积分数，并估计智商（IQ）和记忆评分，以比较不同的治疗模式。
与 DSPT 和 VMAT 相比，PBS 始终降低了颞叶及其亚结构的暴露体积，例如左海马体 V10Gy 从 100%（VMAT）或 41%（DSPT）降至 5%（PBS）（P=0.002）。与两种质子模式相比，VMAT 更好地保护了脑室亚结构。PBS 实现的颞叶剂量降低转化为更好的预测记忆结果，但对估计的 IQ 没有影响。
PBS 始终使颞叶 BSC 的受照体积最低，而基于模型的认知结果估计则不太一致。
