title: Investigation on the reduction of electron contamination with a 6-MV x-ray beam.
abstract: Experimental investigations have been carried out on the reduction of electron contamination of a 6-MV x-ray beam of Clinac model 1800 for square field sizes 5 X 5 to 30 X 30 cm2 in steps of 5 cm and for rectangular field sizes 19 X 7 and 7 X 19 cm2. The electron contamination of both the open beam and the beam with the tray can be effectively reduced by placing a lead foil filter immediately below the blocking tray. Measurements at 100-cm source-skin distance with filter in place showed a reduction in dose in the buildup region and also a displacement of the location of Dmax to greater depths, even for small field sizes such as 10 X 10 cm2.
authors.affiliation: Division of Medical Physics, Evanston Hospital, Northwestern University Medical School, Illinois 60201.
authors.forename: K
authors.initials: K
authors.lastname: Parthasaradhi
authors.forename: S G
authors.initials: SG
authors.lastname: Prasad
authors.forename: B M
authors.initials: BM
authors.lastname: Rao
authors.forename: Y
authors.initials: Y
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Ruparel
authors.forename: R
authors.initials: R
authors.lastname: Garces
mesh_terms: D004583:Electrons; D005374:Filtration / Q000295:instrumentation*; D007854:Lead; D010315:Particle Accelerators; D011882:Radiotherapy, High-Energy / Q000295:instrumentation
chemical_list: D007854:Lead