Axillary radiotherapy for nodal lymphoma: What CTV expansion is required to account for absence of pre-chemotherapy treatment position FDG PET-CT?

Involved site lymphoma radiotherapy clinical target volumes (CTV) require expansion in the absence of treatment-position pre-chemotherapy PET-CT. This prospective imaging study evaluates CTV contouring for axillary lymphoma using diagnostic imaging compared with co-registered treatment-position PET-CT. Generous expansion axially and cranio-caudally is required to encompass pre-chemotherapy disease without treatment-position pre-chemotherapy PET-CT.