Peach Matthew S, Burke Aiden M, Jo Jasmine, Ju Andrew W, Yang Kaida
Department of Radiation Oncology, East Carolina University Brody School of Medicine, Greenville, USA.
Department of Neurology, Vidant Health, Greenville, USA.
Cureus. 2021 Nov 18;13(11):e19717. doi: 10.7759/cureus.19717. eCollection 2021 Nov.
Reirradiation of recurrent glioblastomas is most commonly managed with hypofractionated external beam radiation with a modest overall effect. GammaTile, which is a Cesium-131 source embedded in collagen mesh, is an approach that allows the surgical bed of resectable intracranial tumors to receive a greater biological dose than is possible with any form of external beam radiation therapy (EBRT). In this case report, a 28-year-old male presents with a WHO grade 4 isocitrate dehydrogenase (IDH)-mutant astrocytoma (formerly secondary glioblastoma) of the left occipital/parietal lobe after receiving 45 Gy and two cycles of adjuvant temozolomide four years prior for a grade 3 IDH-mutant astrocytoma. The patient proceeded to undergo craniotomy with maximal safe resection and application of GammaTile to a dose of 60 Gy at 5mm depth. Shortly afterward, he developed symptomatic progression of disease in the bilateral splenium and left thalamus/basal ganglia. We irradiated the undertreated residual disease with EBRT to a dose of 35 Gy in 10 fractions without introducing excessive dose to the GammaTile irradiated volume. This was achieved by creating one portion of the planning target volume with a homogeneous dose and another part where the delivered dose decreased with the GammaTile dose buildup. Treatment planning utilized the Gradient Optimization feathering technique with non-coplanar volumetric modulated arc therapy. The resulting composite between the hypofractionated EBRT and GammaTile dose distribution created an approximate dose equivalent of 50 Gy in 2 Gy fractions to the residual disease with no hot spots or areas of under coverage. This is the first report showing the feasibility of combining GammaTile with dose-matched EBRT volumes in a reproducible manner to sub-totally resected, recurrent intracranial neoplasms.
复发性胶质母细胞瘤的再照射通常采用大分割外照射治疗，总体效果一般。GammaTile是一种嵌入胶原网的铯-131源，该方法能使可切除颅内肿瘤的手术床接受比任何形式的外照射放疗（EBRT）更高的生物剂量。在本病例报告中，一名28岁男性，四年前因三级异柠檬酸脱氢酶（IDH）突变型星形细胞瘤接受了45 Gy的照射及两个周期的辅助替莫唑胺治疗，现左枕叶/顶叶出现世界卫生组织4级IDH突变型星形细胞瘤（原继发性胶质母细胞瘤）。该患者随后接受了开颅手术，进行了最大安全切除，并应用GammaTile至5mm深度处剂量达60 Gy。不久后，他在双侧胼胝体和左侧丘脑/基底神经节出现了有症状的疾病进展。我们用EBRT对未得到充分治疗的残留病灶进行照射，剂量为35 Gy，分10次进行，且未对GammaTile照射体积引入过量剂量。这是通过创建一个具有均匀剂量的计划靶体积部分和另一个剂量随GammaTile剂量积累而降低的部分来实现的。治疗计划采用了梯度优化羽化技术和非共面容积调强弧形治疗。大分割EBRT和GammaTile剂量分布之间的最终合成结果为残留病灶创造了相当于50 Gy、每次2 Gy分割的近似剂量等效，且无热点或照射不足区域。这是首份展示以可重复方式将GammaTile与剂量匹配的EBRT体积相结合用于次全切除的复发性颅内肿瘤的可行性的报告。
