title: Clinic based transfer of the N(D,W)(60Co) calibration coefficient using a linear accelerator.
abstract: Ionization chambers used for reference dosimetry require a local secondary standard ionization chamber with a 60Co absorbed dose to water calibration coefficient N(D,W)(60Co) traceable to a national primary standards dosimetry laboratory or an accredited secondary dosimetry calibration laboratory. Clinic based (in-house) transfer of this coefficient to tertiary reference ionization chambers has traditionally been accomplished with chamber cross calibration in water using a 60Co beam; however, access to 60Co teletherapy machines has become increasingly limited for clinic based physicists. In this work, the accuracy of alternative methods of transferring the N(D,W)(60Co) calibration coefficient using 6 and 18 MV photon beams from a linear accelerator in lieu of 60Co has been investigated for five different setups and four commonly used chamber types.
authors.affiliation: Department of Medical Physics, McGill University Health Centre, 1650 Avenue Cedar Montreal, Quebec H3G 1A4, Canada. wabdel@medphys.mcgill.ca
authors.forename: W
authors.initials: W
authors.lastname: Abdel-Rahman
authors.forename: M D C
authors.initials: MD
authors.lastname: Evans
authors.forename: L
authors.initials: L
authors.lastname: Serré
authors.forename: J P
authors.initials: JP
authors.lastname: McCaffrey
authors.forename: E B
authors.initials: EB
authors.lastname: Podgorsak
authors.forename: J P
authors.initials: JP
authors.lastname: Seuntjens
mesh_terms: D055592:Biophysical Phenomena; D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy; D010315:Particle Accelerators / Q000706:statistics & numerical data*; D019047:Phantoms, Imaging; D011867:Radioisotope Teletherapy / Q000706:statistics & numerical data*; D011874:Radiometry / Q000706:statistics & numerical data; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data; D014867:Water
chemical_list: D003037:Cobalt Radioisotopes; D014867:Water