Anatomic variation of extrahepatic biliary tree structures: importance in treatment planning for radiation therapy.
OBJECTIVE
To demonstrate the variable location of biliary tree components and to assess two treatment planning rules of thumb used for locating porta hepatic nodes for radiation therapy.


METHODS
The distance of the common hepatic duct bifurcation and duodenal papilla from adjacent vertebral bodies was measured on 34 cholangiograms, and their relationships to particular vertebral body levels were recorded. Adequacy of treatment volume to encompass porta hepatic lymph nodes was evaluated in 30 of these cholangiograms by constructing radiation portals according to the two rules of thumb.


RESULTS
Location of the common hepatic duct bifurcation and duodenal papilla varied widely. The treatment portal encompassed 13% (four of 30) of cases when the first rule of thumb was used and 80% (24 of 30) of cases when the second rule of thumb was used.


CONCLUSIONS
The wide variability of location of extrahepatic biliary tree structures suggests the need for individualized treatment planning so that sensitive and dose-limiting healthy tissues can be optimally excluded from radiation treatment portals. Computed tomography and other imaging modalities enable precise location of biliary tree components for radiation treatment planning.
Smith
R G
RG
Department of Radiation Oncology, Emory University College of Medicine, Atlanta, Ga, USA.
Keller
J W
JW
Landry
J C
JC
Tsujino
K
K
Torres
W E
WE
Davis
L W
LW
D014670:Ampulla of Vater / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D018281:Cholangiocarcinoma / Q000000981:diagnostic imaging; D002758:Cholangiography; D004067:Digestive System Neoplasms / Q000532:radiotherapy; D006500:Hepatic Duct, Common / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008099:Liver / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011880:Radiotherapy Planning, Computer-Assisted; D013904:Thoracic Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging