Читать книгу Intracranial Gliomas Part II - Adjuvant Therapy - Группа авторов - Страница 52

Whole-brain radiation therapy (WBRT) of intracranial gliomas has no benefit over partial brain irradiation with focal FRT [12]. However, there is variability in what constitutes partial brain irradiation. Analysis of the patterns of failure has shown that 90% of GBM recurrences occur within 2 cm of the original tumor border [13]. As such, at least a 2–3 cm margin on the resection cavity/residual enhancing disease is typically targeted. Treatment planing is based on MRI. A gross tumor volume (GTV) is defined as the resection cavity with residual enhancing disease with or without surrounding hyperintensity on T2-weighted or fluid-attenuated inversion recovery (FLAIR) images. For example, the Radiation Therapy Oncology Group (RTOG) includes the surrounding T2/FLAIR abnormality as part of the GTV while the European Organization for Research and Treatment of Cancer (EORTC) does not. A clinical target volume (CTV) includes a 2–3 cm at-risk margin surrounding the GTV shortened when appropriate around anatomical barriers (e.g., bone, falx, tentorium). A planning target volume (PTV) includes an additional 3–5 mm of margin to account for daily setup uncertainty. The PTV is ultimately the volume targeted with the prescription dose.