Set-up errors and planning target volume margins in head and neck cancer radiotherapy: a clinical study of image guidance with on-line cone-beam computed tomography

Background Set-up errors represent a source of uncertainty in head and neck (H&N) cancer radiotherapy. The present study evaluated set-up accuracy with the use of cone-beam computed tomography (CBCT) in order to establish the proper clinical target volume (CTV) to planning target volume (PTV) margins to be adopted.