title: Verification of dose calculations with a treatment planning system for open and wedged fields of a 60Co unit with a new asymmetric collimator.
abstract: A Cobalt-60 treatment unit was equipped with a new collimator with asymmetrical capability of both the X-and Y-jaws. This new collimator design opens possibilities for treatment techniques with this apparatus, which, until now, were only achievable with linear accelerators. Before accepting the device and taking it into clinical routine, a dosimetric verification was performed, which compared results of dose measurements with the results of dose calculations of the treatment planning system. For this purpose, the approach of Report 55 of the AAPM Task Group 23 for testing a treatment planning system was followed, with modifications to comply with the asymmetrical settings of the fields. The study shows that criteria for acceptance of the treatment planning algorithm were met for the asymmetrical open fields and for asymmetrical fields with a 22 degrees and a 45 degrees wedge. However, deviations tended to be too high under the thick part of the thickest wedge.
authors.affiliation: Department of Clinical Physics, Dr. B. Verbeeten Institute, Tilburg, The Netherlands. Venselaar@bvi.nl
authors.forename: J L
authors.initials: JL
authors.lastname: Venselaar
authors.forename: H W
authors.initials: HW
authors.lastname: Bierhuizen
authors.forename: P H
authors.initials: PH
authors.lastname: Van Der Giessen
mesh_terms: D000465:Algorithms; D003037:Cobalt Radioisotopes / Q000592:standards; D004867:Equipment Design; D006801:Humans; D008432:Mathematical Computing; D009369:Neoplasms / Q000532:radiotherapy*; D011878:Radiotherapy / Q000295:instrumentation* / Q000592:standards*; D011879:Radiotherapy Dosage / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000592:standards*; D015203:Reproducibility of Results
chemical_list: D003037:Cobalt Radioisotopes