title: The calibration of plane parallel ionisation chambers for the measurement of absorbed dose in electron beams of low to medium energies. Part 2: The PTW/MARKUS chamber.
abstract: The purpose of Part 2 study of calibration methods for plane parallel ionisation chambers was to determine the feasibility of using beams of calibration of the MARKUS chamber other than the standard AAPM TG39 reference beams of 60Co and a high energy electron beam (E0 > or = 15 MeV). A previous study of the NACP chamber had demonstrated an acceptable level of accuracy with corresponding spread of -0.5% to +0.8% for its calibration in non-standard situations (medium to low energy electron and photon beams). For non-standard situations the spread in NDMARKUS values was found to be +/-2.5%. The results suggest that user calibrations of the MARKUS chamber in non-standard situations are associated with more uncertainties than is the case with the NACP chamber.
authors.affiliation: Department of Radiation Oncology, St Vincent's Hospital, Darlinghurst, NSW.
authors.forename: P
authors.initials: P
authors.lastname: Cross
authors.forename: N
authors.initials: N
authors.lastname: Freeman
mesh_terms: D002138:Calibration; D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D011874:Radiometry / Q000295:instrumentation*; D011879:Radiotherapy Dosage
chemical_list: D003037:Cobalt Radioisotopes