title: Implication of Bifurcation of Abdominal Aorta for Radiotherapy Planning for Cervical Cancers.
abstract: BACKGROUND
  External Beam Radiotherapy plays a major role in the management of Carcinoma Cervix. The Radiotherapy treatment portals are designed to adequately cover the gross disease and areas of microscopic spread. The upper border of Radiotherapy field is traditionally placed at the level of L4-L5 intervertebral space to cover the common iliac nodal area. It is determined based on anatomical and surgical series which have shown that division of Abdominal aorta occurs at that level.
  
  
  OBJECTIVE
  To study the level of the division of abdominal aorta in relation to the lumbar vertebral levels. To propose the change in the upper border of Radiotherapy portals used in the treatment of Cervical Cancers.
  
  
  METHODS
  Patients who underwent Radiotherapy for Cervical Cancer from December 2010 to January 2012 formed the subjects of this prospective study. All the patients underwent aquaplast immobilization in supine position and contrast enhanced Computed Tomography (CT) simulation for Radiotherapy planning following bladder protocol. The Radiotherapy planning was done on commercial treatment planning system, Prowess version 4.71. The level of division of Abdominal Aorta into right and left Common Iliac arteries with respect to vertebral level was determined and studied.
  
  
  RESULTS
  The division of abdominal aorta into common iliac arteries occurred at the level of L3-L4 intervertebral space, in front of body of L4 vertebra and L4-L5 intervertebral space in 53.84%, 30.76% and 15.40% of the patients respectively.
  
  
  CONCLUSIONS
  The division of abdominal aorta occurs at a higher level than L4-L5 intervertebral space in majority of patients. It is highly recommended to use CT scan based planning. However, in institutes where there are no facilities for CT based planning, it is advisable to shift the upper border of Radiotherapy treatment portal above the L3-L4 intervertebral space for delivering adequate doses to the common iliac lymphnodes.
authors.affiliation: Associate Professor, Department of Radiation Oncology, M.S. Ramaiah Medical College Hospital , Bangalore, India .
authors.forename: Thiru Raju Arul
authors.initials: TR
authors.lastname: Ponni
authors.affiliation: Senior Resident, Department of Radiation Oncology, St John's Medical College Hospital , Bangalore, India .
authors.forename: Handanakere Udayashankara
authors.initials: HU
authors.lastname: Avinash
authors.affiliation: Professor, Department of Radiation Oncology, M.S. Ramaiah Medical College Hospital , Bangalore, India .
authors.forename: Manur Gururajachar
authors.initials: MG
authors.lastname: Janaki
authors.affiliation: Associate Professor, Department of Radiation Oncology, M.S. Ramaiah Medical College Hospital , Bangalore, India .
authors.forename: Agrahara Srinivas Kirthi
authors.initials: AS
authors.lastname: Koushik
authors.affiliation: Assistant Professor, Department of Radiation Oncology, M.S. Ramaiah Medical College Hospital , Bangalore, India .
authors.forename: Mohan Kumar
authors.initials: MK
authors.lastname: Somashekar
keywords: Carcinoma cervix; Conventional radiotherapy; Division of abdominal aorta
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