Radiation therapy (RT) for the management of lymphoma has evolved over the past few decades. Large, extended, or involved fields have been replaced by smaller involved sites or nodal volumes. Currently, customized plans are created for each individual patient, and these plans encompass only the areas involved by disease. A critical factor that has enabled this shift in practice is the evolving use of imaging studies. Imaging plays a key role in patient selection and RT planning and delivery. The objective of this manuscript is to provide guidelines for best practice of use of imaging in pretreatment evaluation, treatment choice, RT target volume definition, and RT treatment verification and delivery.