Oncolytic virus-mediated tumor eradication can be evaluated noninvasively using the phosphorylation of radiolabeled thymidine analogs such as [125I or 124I]-FIAU (fial2′-fluoro-2′-deoxy-1-β-d-arabinofuranosyl-5-iodouracil), as well as radiolabeled guanosine analogs like 8-[18F]-fluoroganciclovir (18F-FGCV) and [18F]-FHBG (9-(4-fluoro-3-hydroxymethylbutyl) guanine) by HSV-1-TK [25, 35]. Here, TKT is linked to neoplasm.