title: Measurement of Prepl Pwall factors in electron beams and in a 60Co beam for plane-parallel chambers.
abstract: This paper describes a method to measure the product of Prepl Pwall correction factors for ionization chambers and presents our measured values of Prepl Pwall for Markus plane-parallel chambers in electron beams. It is shown that the measured values of Prepl Pwall can be fitted to an equation, Prepl Pwall = c1 + c2 R50 + c3 (R50)2, for Markus chambers at the new reference depth for electron beams (6 MeV < or = nominal energy E < or = 20 MeV). We also present our measured values of Prepl Pwall for NACP and Markus chambers in a water phantom irradiated in a 60Co beam.
authors.affiliation: Fraser Valley Cancer Centre, British Columbia Cancer Agency, Surrey, Canada. gding@bccancer.bi.ca
authors.forename: G X
authors.initials: GX
authors.lastname: Ding
authors.forename: J E
authors.initials: JE
authors.lastname: Cygler
mesh_terms: D002138:Calibration; D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D004583:Electrons; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014867:Water
chemical_list: D003037:Cobalt Radioisotopes; D014867:Water