Fan Xing-Wen, Wang Juan-Qi, Wu Jun-Lan, Wang Hong-Bing, Wu Kai-Liang
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China; Department of Oncology, Shanghai Armed Police Corps Hospital, Shanghai 201103, China.
Med Dosim. 2019;44(2):130-135. doi: 10.1016/j.meddos.2018.04.004. Epub 2018 May 31.
Whole brain radiotherapy (WBRT) is the preferred treatment for multiple brain metastases, and patients with limited-stage small cell lung cancer undergo prophylactic cranial irradiation after complete remission. However, neurotoxicity remains a complication. In addition to protecting the hippocampus from irradiation to preserve cognitive function, it is also critical to avoid irradiating the hypothalamic-pituitary axis to preserve endocrine and immune function. This study aimed to evaluate the feasibility of delivering WBRT while protecting the hippocampus and hypothalamic-pituitary axis. Thirteen patients with limited-stage small cell lung cancer were enrolled in this study. The hippocampus, hypothalamus, and pituitary gland were contoured based on T1-weighted magnetic resonance imaging. The prescribed dose to the whole brain planning target volume was 25 Gy in 10 fractions. Two treatment plans using equispaced coplanar intensity-modulated radiotherapy (IMRT) were generated: WBRT with hippocampus avoidance (H-A) and WBRT with hippocampus, hypothalamus, and pituitary gland avoidance (H-HP-A). Both "H-A" and "H-HP-A" plans successfully protected the hippocampus, which received mean doses of 9.1 and 9.6 Gy, respectively (p = 0.0002), whereas the "H-HP-A" plan decreased the doses to both the hypothalamus (mean dose 11.06 Gy) and the pituitary gland (mean dose 10.66 Gy). Both "H-A" and "H-HP-A" plans showed similar target coverage of 95.1%. The homogeneity index of the "H-A" plan was slightly better than that of the "H-HP-A" plan (0.20 vs 0.23, p= 0.0012). In conclusion, the use of equispaced coplanar IMRT was found to simultaneously protect the hippocampus and hypothalamic-pituitary axis while delivering WBRT with acceptable target coverage and homogeneity.
全脑放疗（WBRT）是多发性脑转移瘤的首选治疗方法，局限期小细胞肺癌患者在完全缓解后接受预防性颅脑照射。然而，神经毒性仍然是一种并发症。除了保护海马体免受照射以保留认知功能外，避免照射下丘脑 - 垂体轴以保留内分泌和免疫功能也至关重要。本研究旨在评估在保护海马体和下丘脑 - 垂体轴的同时进行WBRT的可行性。13例局限期小细胞肺癌患者纳入本研究。根据T1加权磁共振成像勾勒出海马体、下丘脑和垂体的轮廓。全脑计划靶体积的处方剂量为25 Gy，分10次给予。生成了两个使用等间距共面调强放疗（IMRT）的治疗计划：避免海马体的WBRT（H - A）和避免海马体、下丘脑和垂体的WBRT（H - HP - A）。“H - A”和“H - HP - A”计划均成功保护了海马体，其平均剂量分别为9.1 Gy和9.6 Gy（p = 0.0002），而“H - HP - A”计划降低了下丘脑（平均剂量11.06 Gy）和垂体（平均剂量10.66 Gy）的剂量。“H - A”和“H - HP - A”计划的靶区覆盖率相似，均为95.1%。“H - A”计划的均匀性指数略优于“H - HP - A”计划（0.20对0.23，p = 0.0012）。总之，发现使用等间距共面IMRT在进行WBRT时能同时保护海马体和下丘脑 - 垂体轴，且靶区覆盖率和均匀性可接受。
