title: A method for producing uniform dose distributions in the junction regions of large hinge angle electron fields.
abstract: OBJECTIVE
  The planning problems presented by abutting electron fields are well recognized. Junctioning electron fields with a large hinge angle compounds the problems because of the creation of closely situated high dose and low-dose regions.
  
  
  METHODS
  The technique involving a compensated superficial x-ray (SXR) field to treat the junction region between electron fields was developed and used in a particular clinical case (treatment of a squamous cell carcinoma of the forehead/scalp). The superficial x-ray beam parameters were chosen and the compensator was designed to make the SXR field complementary to the electron fields.
  
  
  RESULTS
  Application of a compensated SXR field eliminated low dose zones in the junction region and reduced high dose zones to 110%. In the clinical case discussed, the high-dose areas due to the SXR field would not appear because of increased attenuation of the soft X-rays in bone.
  
  
  CONCLUSIONS
  The technique proposed produces uniform dose distribution up to 3 cm deep and can be considered as an additional tool for dealing with electron field junctioning problems.
authors.affiliation: Department of Medical Physics, Royal Adelaide Hospital, SA, Australia. szavgoro@physics.adelaide.edu.au
authors.forename: S F
authors.initials: SF
authors.lastname: Zavgorodni
authors.forename: W A
authors.initials: WA
authors.lastname: Beckham
authors.forename: D E
authors.initials: DE
authors.lastname: Roos
mesh_terms: D000368:Aged; D004583:Electrons; D005260:Female; D006801:Humans; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage