Anatomical structures for the high risk lymph nodal regions of the head pancreatic cancer. Transverse CT slices through high risk lymph node regions of the head pancreatic cancer from cranial to caudal direction. The abdominal artery and the anatomical structures were identified as a surrogate target for lymph node regions. A margin of 10 mm was added to the artery to delineate lymph node area, including the soft tissue with lymphatic and neural plexus. CTV was formed by the union of the identified lymph node areas. Abbreviations: Ao = Aorta; APLn = Anterior Pancreaticoduodenal Lymph nodes; CBD = Common Bile Duct; CeLn = Celiac Lymph nodes; CHA = Common Hepatic Artery; ChLn = Common hepatic and hepatoduodenal ligament Lymph nodes; CT = Celiac Trunk; 1st D = first part of Duodenum; GdA = Gastroduodenal Artery; InLn = Infrapyloric Llymph nodes; IPdA = Inferior Pancreaticoduodenal Artery; IVC = Inferior Vena Cava; JA = Jejunal Artery; MCA = Medial Colic Artery; PaLn = Paraaortic Lymph nodes; Pb = Pancreatic body; Ph = Pancreatic head; Pt = Pancreatic tail; Pyl = Pylorus; PPLn = Posterior Pancreaticoduodenal Lymph nodes; PV = Portal Vein; 2nd D = second part of Duodenum; SMA = Superior Mesenteric Artery; SMLn = Superior Mesenteric Lymph nodes; SMV = Superior Mesenteric Vein; SPdA = Superior Pancreaticoduodenal Artery; SpV = Splenic Vein; * = pillar of the diaphragm.