title: Comparative evaluation of Wellhöfer ion chamber array and Scanditronix diode array for dynamic wedge dosimetry.
abstract: Normalised profiles have been measured using the Scanditronix diode array and the Wellhöfer ion chamber array for the Varian dynamic wedge. Agreement was of the order of 0.1% of central axis peak dose for an open beam at depth, 0.3% for a dynamic wedge field at depth, and up to 0.6% at the peak depth. The use of the arrays for data acquisition is discussed, including user interface limitations. Data reproducibility is determined to be of the order of 0.1% for both systems. The issue of beam hardening within dynamic wedges is discussed and resolved in terms of the dose-gradient effect. A method for interpolation between dynamic wedge profiles using open beam data is presented that allows construction of isodoses to an estimated accuracy of 0.7%. Finally a benchmark for comparison of different measuring systems based on quality assurance requirements for the enhanced dynamic wedge is suggested.
authors.affiliation: Department of Physical Sciences, Peter MacCallum Cancer Institute, East Melbourne, Victoria. tackerly@petermac.unimelb.edu.au
authors.forename: T
authors.initials: T
authors.lastname: Ackerly
authors.forename: S
authors.initials: S
authors.lastname: Todd
authors.forename: I
authors.initials: I
authors.lastname: Williams
authors.forename: M
authors.initials: M
authors.lastname: Geso
authors.forename: J
authors.initials: J
authors.lastname: Cramb
mesh_terms: D010315:Particle Accelerators; D011879:Radiotherapy Dosage; D013679:Technology, Radiologic