Background:
There are many challenges in oncologic imaging including: more accurate staging, determine site with highest probability of tumor existence for biopsy, especially for brain tumors because of the sensitive anatomical position, determine the exact location of the tumor for radiotherapy treatment planning and etc. Positron emission tomography (PET) is imaging modality which provides some special functional information. The basis of the PET system is detection of tow photons which are generated by positron/electron encounter which occurs directly after positron emission by radionuclide. However, it is powerless in providing anatomical information. Computed tomography (CT) generates three dimensional reconstructions of patients anatomy based on differences in X-ray attenuation. Combination of PET and CT is able to provide anatomical and physiological information of patients synchronizes.