Mireștean Camil Ciprian, Buzea Călin Gheorghe, Zară Alexandru Dumitru, Iancu Roxana Irina, Iancu Dragoș Petru Teodor
Regional Institute of Oncology, 700483 Iaşi, Romania.
"Prof. Dr. N. Oblu" Emergency Clinic Hospital, 700309 Iași, Romania.
Medicina (Kaunas). 2025 Apr 27;61(5):810. doi: 10.3390/medicina61050810.
: Brain radionecrosis is an under-recognized but potentially life-altering late complication of radiotherapy in patients with locally advanced nasopharyngeal cancer. Temporal lobe radionecrosis and high-dose exposure to the hippocampus are strongly associated with cognitive decline and radiation-induced dementia, negatively impacting patients' long-term quality of life (QoL). This study aimed to evaluate and compare radiation dose distributions to critical brain structures across three radiotherapy techniques-3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT)-in order to assess potential neurocognitive risks and support hippocampal-sparing protocols. : Ten patients previously treated with 3D-CRT were retrospectively replanned using IMRT and VMAT techniques on the Eclipse v13.3 (VARIAN) planning system. Bilateral hippocampi and temporal lobes were delineated as organs at risk (OARs) according to the RTOG atlas, and dosimetric parameters including D_max, D_mean, and D_min were recorded. V7.3 values were evaluated for hippocampal avoidance regions. : While IMRT and VMAT provided improved target volume coverage and reduced high-dose exposure to many standard OARs, both techniques were associated with increased D_mean and D_min to the hippocampus and temporal lobes compared to 3D-CRT. The highest D_max values to the temporal lobes were observed in 3D-CRT plans, indicating a potential risk of radionecrosis. VMAT plans showed hippocampal mean doses exceeding 10 Gy in some cases, with V7.3 > 40%, breaching established neurocognitive risk thresholds. : These findings support the routine delineation of the hippocampus and temporal lobes as OARs in radiotherapy planning for nasopharyngeal cancer. The implementation of hippocampal-sparing strategies, particularly in IMRT and VMAT, is recommended to reduce the risk of radiation-induced cognitive toxicity and preserve long-term QoL in survivors.
脑放射性坏死是局部晚期鼻咽癌患者放疗后一种未被充分认识但可能改变生活的晚期并发症。颞叶放射性坏死和海马体高剂量照射与认知功能下降和放射性痴呆密切相关，对患者的长期生活质量产生负面影响。本研究旨在评估和比较三种放疗技术——三维适形放疗（3D-CRT）、调强放疗（IMRT）和容积调强弧形放疗（VMAT）——对关键脑结构的辐射剂量分布，以评估潜在的神经认知风险并支持海马体保护方案。
对10例先前接受3D-CRT治疗的患者在Eclipse v13.3（瓦里安）计划系统上使用IMRT和VMAT技术进行回顾性重新计划。根据RTOG图谱将双侧海马体和颞叶划定为危及器官（OARs），并记录包括D_max、D_mean和D_min在内的剂量学参数。对海马体避让区域评估V7.3值。
虽然IMRT和VMAT提供了更好的靶区覆盖，并减少了对许多标准OARs的高剂量照射，但与3D-CRT相比，这两种技术均与海马体和颞叶的D_mean和D_min增加有关。在3D-CRT计划中观察到颞叶的D_max值最高，表明存在放射性坏死的潜在风险。VMAT计划在某些情况下显示海马体平均剂量超过10 Gy，V7.3>40%，突破了既定的神经认知风险阈值。
这些发现支持在鼻咽癌放疗计划中将海马体和颞叶常规划定为OARs。建议实施海马体保护策略，尤其是在IMRT和VMAT中，以降低放射性认知毒性风险并保留幸存者的长期生活质量。
