In the past few years, positron emission tomography/computed tomography (PET/CT) imaging has increasingly been used for the diagnosis, staging, and restaging of malignant diseases. The success of this emerging modality has primarily been due to its ability to combine the advantages of both PET and CT imaging while minimizing their separate weaknesses. The aim of this paper is to provide an overview of the basis behind PET/CT imaging, its advantages, and discuss its imaging artifacts with special emphasis on proposed correction techniques. A brief discussion regarding the use of PET/CT imaging for radiation treatment planning is also presented.