title: Modelling simple helically delivered dose distributions.
abstract: In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored.
authors.affiliation: Department of Human Oncology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, USA. john.fenwick@ccotrust.nhs.uk
authors.forename: John D
authors.initials: JD
authors.lastname: Fenwick
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Tomé
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kissick
authors.forename: T Rock
authors.initials: TR
authors.lastname: Mackie
mesh_terms: D001822:Body Burden; D003198:Computer Simulation; D019544:Equipment Failure Analysis / Q000379:methods; D008954:Models, Biological; D015233:Models, Statistical; D011785:Quality Assurance, Health Care / Q000379:methods; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000379:methods*; D012062:Relative Biological Effectiveness