[Radiotherapy of cancers of the pancreas and extrahepatic biliary tree. Gross tumor volume (GTV). Clinical target volume (CTV)].

Anatomical data of pancreas, biliary tree, regional lymph nodes is required to define GTV and CTV. In case of postoperative irradiation, CTV is designed in collaboration with radiation oncologist and surgeon oncologist. For exclusive radiotherapy, endodigestive ultrasonography, CT scan and MRI could help radiation oncologist defining GTV. Although, accuracy of all the imaging techniques in past years remains poor. Currently, no available literature is published regarding security margins for the definition of CTV. Therefore, recommendations according to clinical experience are proposed.