Feasibility testing of a simultaneous sparing approach of hippocampus, hypothalamus and pituitary gland in patients undergoing whole-brain radiotherapy (WBRT) with and without a concomitant boost to metastatic sites. Cognitive impairment and hormonal dysfunction are common side effects of cranial radiotherapy. A reduced dose application to the patho-physiologically involved functional brain areas, i.e. hippocampus, hypothalamus and pituitary gland, could reduce these common side effects. While hippocampal sparing is already a common practice to improve cognitive outcome, technical experience of additional combined sparing of the hypothalamus/pituitary gland (HT-P) is insufficient. Twenty patients were included in the planning study. In 11 patients, a total dose of 36 Gy of WBRT (2 Gy per fraction) plus a simultaneous integrated boost (SIB) of 9 Gy (0.5 Gy per fraction, total dose: 45 Gy) to the brain metastases was applied. In 9 patients, prophylactic cranial irradiation (PCI) was simulated with a total dose of 30 Gy (2 Gy per fraction). In both patient cohorts, a sparing approach of the hippocampus and the HT-P area was simulated during WBRT. For all treatment plans, volumetric modulated arc therapy (VMAT) was used. Quality assurance included assessment of homogeneity, conformality and target coverage. The mean dose to the hippocampus and HT-P region was limited to less than 50% of the prescribed dose to the planning target volume (PTV) in all treatment plans. Dose homogeneity (HI) of the target volume was satisfying (median HI = 0.16 for WBRT+SIB and 0.1 for PCI) and target coverage (conformation number, CN) was not compromised (median CN = 0.82 for SIB and 0.86 for PCI). Simultaneous dose reduction to the hippocampus and the HT-P area did not compromise the PTV coverage in patients undergoing WBRT+SIB or PCI using VMAT. While the feasibility of the presented approach is promising, prospective neurologic, endocrine outcome and safety studies are required.

中文翻译：

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在全脑放射治疗期间保护海马体和下丘脑-垂体区域：体积调制弧形治疗计划研究。


对接受全脑放疗 (WBRT) 的患者进行海马体、下丘脑和垂体同时保留方法的可行性测试，无论是否同时对转移部位进行加强治疗。认知障碍和激素功能障碍是颅脑放疗的常见副作用。减少对涉及病理生理学的功能性大脑区域（即海马体、下丘脑和垂体）的剂量，可以减少这些常见的副作用。虽然海马保留已经是改善认知结果的常见做法，但额外的下丘脑/垂体联合保留（HT-P）的技术经验还不够。二十名患者被纳入计划研究中。在 11 名患者中，对脑转移瘤应用了总剂量 36 Gy 的 WBRT（每次 2 Gy）加上 9 Gy（每次 0.5 Gy，总剂量：45 Gy）的同时积分加强 (SIB)。对 9 名患者进行了模拟预防性颅脑照射 (PCI)，总剂量为 30 Gy（每次 2 Gy）。在这两个患者队列中，在 WBRT 期间模拟了海马和 HT-P 区域的保留方法。所有治疗计划均采用容积调节弧疗法 (VMAT)。质量保证包括对同质性、共形性和目标覆盖率的评估。在所有治疗计划中，海马和 HT-P 区域的平均剂量限制为低于计划目标体积 (PTV) 处方剂量的 50%。靶区的剂量均匀性 (HI) 令人满意（WBRT+SIB 的中位 HI = 0.16，PCI 的中位 HI = 0.1），并且靶区覆盖范围（构象数 CN）未受影响（SIB 的中位 CN = 0.82，PCI 的中位 CN = 0.86）。 同时减少海马和 HT-P 区域的剂量不会影响接受 WBRT+SIB 或使用 VMAT 进行 PCI 的患者的 PTV 覆盖范围。虽然所提出的方法的可行性很有希望，但仍需要进行前瞻性神经学、内分泌结果和安全性研究。