The optimal management of children with Hodgkin lymphoma (HL) should limit the risk of treatment-related toxicity without compromising disease control. Consequently, increasing effort is being directed to retaining the demonstrated efficacy of radiation therapy (RT) in maximizing the cure of HL while reducing the radiation exposure of normal tissues. Historically, guidelines for RT volume definition used in pediatric HL trials have referenced 2-dimensional imaging and bony landmarks to define classical involved field RT. With recognition of the efficacy of chemotherapy, the data on the adverse late effects of radiation, and the evolution of advanced imaging techniques that reveal the location of both tumor and normal tissues, it is necessary that radiation techniques for children and adolescents be refined. The concepts described by the International Commission on Radiation Units provide a common approach for field definition using 3-dimensional computed tomographic--based RT planning and volumetric image guidance. Here we describe the application of these concepts in the planning of RT for pediatric HL. This will be increasingly important as current and upcoming pediatric HL trials will employ these concepts to deliver RT.