title: The matching of wedge transmission factors across six multi-energy linear accelerators.
abstract: Elekta Precise linear accelerators create a wedged isodose distribution using a single, fixed, motorized wedge with a nominal wedge angle of 60 degrees. Wedge angles of less than 60 degrees can be produced by varying the proportion of open and wedge monitor units for a given exposure. The fixed wedge can be replaced with a mobile wedge, the position of which can be moved in order to adjust the wedge transmission factor (WTF). Using the original fixed wedges installed in our fleet of six Elekta accelerators, we found a range of 4% in measured wedge transmission factor for 6 MV beams. Results are presented which demonstrate that by using the mobile wedge it is possible to match the wedge transmission factors to within 1% for the six linear accelerators over three energies.
authors.affiliation: Department of Medical Physics, Cookridge Hospital, Leeds Teaching Hospitals Trust, Leeds LS16 6QB, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Weston
authors.forename: R C A
authors.initials: RC
authors.lastname: Thompson
authors.forename: A M
authors.initials: AM
authors.lastname: Morgan
mesh_terms: D002138:Calibration; D004867:Equipment Design; D010315:Particle Accelerators / Q000592:standards*; D019047:Phantoms, Imaging; D011786:Quality Control; D016634:Radiosurgery / Q000295:instrumentation* / Q000592:standards; D012015:Reference Standards