Revised guidelines for the staging and response criteria of Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL) were recently published to include the expanding role of positron emission tomography/computed tomography (PET/CT) using (18)F-fluoro-2-deoxyglucose. Here, we discuss the new guidelines and the need for standardized PET acquisition and interpretation in HL and NHL. We also discuss how the role for CT is evolving in the process of making treatment decisions and provide insight on how best to standardize the use of PET/CT for making therapeutic choices.