We showed that although the 18F-Z HER2-Affibody radiotracer in PET imaging is often used for characterization of tumors rather than detection, sensitivity and specificity of the localized radiotracer in the tumor region were informative enough; therefore, roughly determined tumor regions from PET images guided the delineation process well in the anatomical image domain for extracting accurate tumor volume information. Here, ERBB2 is linked to neoplasm.