PET/CT proved significantly more accurate in assessing tumors. It has become an important means of diagnosing different neoplastic lesions. Tumor staging with PET/CT is significantly more accurate than CT alone, PET alone, and side-by-side PET + CT. This diagnostic advantage translates into treatment plan changes in a substantial number of patients. This technique provides necessary information needed for tumor detection and staging.In our study we reviewed the advantages, clinical effects and accuracy of the PET/CT examinations and to determine the diagnostic improvement of fused PET/CT images compared with CT or PET images alone in tumor evaluation.