The association of linear energy transfer and dose with radiation necrosis after pencil beam scanning proton therapy in pediatric posterior fossa tumors: Association of dose and LET with radiation necrosis.

IF 6.4 1区医学 Q1 ONCOLOGY International Journal of Radiation Oncology Biology Physics Pub Date : 2024-11-21 DOI:10.1016/j.ijrobp.2024.11.086

Jarey H Wang, Ryan Oglesby, Anh Tran, Melike Guryildirim, Mattea Miller, Khadija Sheikh, Heng Li, Matthew Ladra, William T Hrinivich, Sahaja Acharya

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Abstract

Introduction: Proton therapy is the preferred treatment modality for most pediatric central nervous system (CNS) tumors. The risk of radiation necrosis may be increased at the distal end of the beam due to an increase in linear energy transfer (LET) and relative biological effective (RBE) dose. We report on the association of linear energy transfer (LET) and dose with radiation necrosis after pencil beam scanning proton therapy in pediatric posterior fossa tumors using a case-control framework.

Materials and methods: From 2019 to 2022, 33 patients less than or equal to 18 years of age treated with first line proton therapy for primary tumors in the posterior fossa and with 6 or more months of follow up MRI imaging were retrospectively identified. Nine patients with imaging changes consistent with necrosis were matched with controls in a 1:2 fashion based on age, sex, dose, and follow-up time from proton therapy. Dose [Gy (RBE)] and dose-averaged LET (LETd) values for target structures and organs at risk (OAR) were computed and compared between cases and controls.

Results: Within the whole cohort, mean age was 6.6 years (SD=4.77) with a median follow up time of 24.1 months. Within the case-control matched cohort (18 controls, 9 cases), there were no significant differences in age, sex, time to follow up, tumor location, dose, and use of concurrent chemotherapy. Mean time to necrotic imaging finding was 4.47 months (SD=2.03). Cases demonstrated significantly higher brainstem D50 (p=0.02). LETd was not different between cases and controls. However, when using a combined metric of higher brainstem dose (> 47.5 [Gy (RBE)]) and higher LETd (>3.5 keV/µm), a greater proportion of cases compared to controls met this metric (89% vs. 39%, p=0.02).

Conclusions: Combined effects of intermediate-to-high dose and LETd in the brainstem may contribute to greater necrosis risk after pencil beam scanning proton therapy in children with posterior fossa tumors.

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铅笔束扫描质子治疗小儿后窝肿瘤后线性能量传递和剂量与辐射坏死的关系：剂量和线性能量传输与辐射坏死的关系

介绍：质子疗法是大多数儿科中枢神经系统（CNS）肿瘤的首选治疗方式。由于线性能量传递（LET）和相对生物有效剂量（RBE）的增加，射束远端的辐射坏死风险可能会增加。我们采用病例对照框架报告了小儿后窝肿瘤铅笔束扫描质子治疗后线性能量传递（LET）和剂量与辐射坏死的关系：从2019年至2022年，对33名小于或等于18岁的后窝原发性肿瘤一线质子治疗患者进行了回顾性鉴定，并进行了6个月或更长时间的磁共振成像随访。根据年龄、性别、剂量和质子治疗后的随访时间，将影像学变化与坏死一致的 9 例患者与对照组按 1:2 的比例进行配对。计算了靶结构和危险器官（OAR）的剂量[Gy (RBE)]和剂量平均 LET (LETd)值，并对病例和对照组进行了比较：整个队列的平均年龄为 6.6 岁（SD=4.77），中位随访时间为 24.1 个月。在病例对照匹配队列（18 名对照组患者，9 名病例组患者）中，年龄、性别、随访时间、肿瘤位置、剂量以及是否同时接受化疗等方面均无显著差异。影像学发现坏死的平均时间为 4.47 个月（SD=2.03）。病例的脑干D50明显更高（P=0.02）。病例和对照组的 LETd 没有差异。然而，当使用较高脑干剂量（> 47.5 [Gy (RBE)]）和较高 LETd（>3.5 keV/µm）的综合指标时，符合该指标的病例比例高于对照组（89% vs. 39%，p=0.02）：结论：脑干中高剂量和LETd的综合效应可能会导致后窝肿瘤患儿在接受铅笔束扫描质子治疗后出现更高的坏死风险。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Radiation Oncology Biology Physics 医学-核医学

CiteScore

11.00

自引率

7.10%

发文量

2538

审稿时长

6.6 weeks

期刊介绍： International Journal of Radiation Oncology • Biology • Physics (IJROBP), known in the field as the Red Journal, publishes original laboratory and clinical investigations related to radiation oncology, radiation biology, medical physics, and both education and health policy as it relates to the field. This journal has a particular interest in original contributions of the following types: prospective clinical trials, outcomes research, and large database interrogation. In addition, it seeks reports of high-impact innovations in single or combined modality treatment, tumor sensitization, normal tissue protection (including both precision avoidance and pharmacologic means), brachytherapy, particle irradiation, and cancer imaging. Technical advances related to dosimetry and conformal radiation treatment planning are of interest, as are basic science studies investigating tumor physiology and the molecular biology underlying cancer and normal tissue radiation response.