Conventional MR imaging, Target volume and Dosimetry of a Low-grade Glioma. A left thalamic low-grade oligodendroglioma in a 10 year-old boy after partial resection, without contrast enhancement. [A] T1-weighted transaxial MR image after administration of intravenous Gd-DTPA [B] T2 -weighted sequence which shows ill-defined nodular images. [C] Representation of Gross tumor volume (in red) and Clinical target volume (in green). [D] Radiation field encompassing medial part of the left thalamus.