In our previous report[35], we used C6 cells to construct C6TL cells containing the herpes simplex virus type-1 thymidine kinase (HSV1-tk) and firefly luciferase (fLuc) genes for gene therapy against glioma and found that the genetically modified C6 cell line is a very effective monitoring system for Bioluminescence imaging or microPET due to their high fLuc activity and iodine-125 iodovinyldeoxyuridine uptake. Here, TKT is linked to glioma.