Additional PET-CT will not increase radiation dose significantly. The mean estimated radiation dose for a limited CT of the chest is about 14 mSv (i.e., 7mSv for limited diagnostic CT and FDG ([18F]-fluorodeoxyglucose), each). The dynamic stage will add radiation dose of about 0.3mSv. Of note, the significance of adding radiation dose is less of importance with regard to treatment of patients with aggressive cancer.