Purpose: In this work, we describe five oncology patients whose clinical management were uniquely benefited by a novel scanner that acquires positron emission tomography (PET) and x-ray computed tomography (CT) in the same imaging session.Procedures: Co-registered 2-[F(18)]-fluoro-2-deoxy-D-glucose (FDG)-PET and CT images were acquired using a combined PET/CT scanner. Pathology and clinical follow-up data were used to confirm PET/CT scan results.Results: The combined PET/CT scanner demonstrated the ability to distinguish malignant lesions from normal physiologic FDG uptake in the striated muscles of the head and neck as well as excretory and bowel activity in the abdomen and pelvis. Additionally, the technology positively affected patient management through localization for surgical and radiation therapy planning as well as assessment of tumor response.Conclusion: Our experience indicates that simultaneous acquisition of co-registered PET and CT images enabled physicians to more precisely discriminate between physiologic and malignant FDG uptake and more accurately localize lesions, improving the value of diagnostic PET in oncologic applications.