title: Comparison of build-up dose between Elekta and Varian linear accelerators for high-energy photon beams using radiochromic film and clinical implications for IMRT head and neck treatments.
abstract: Skin toxicity has been reported for IMRT of head and neck cancer. The purpose of this study was to investigate the dose in the build-up region delivered by a 6 MV treatment plan for which important skin toxicity was observed. We also investigated if the different designs of the treatment head of an Elekta and a Varian linear accelerator, especially the lower position of the Varian multi-leaf collimator, give rise to different build-up doses. For regular square open beams, the build-up dose along the central beam axis is higher for the Varian machine than for the Elekta machine, both for 6 MV and 18 MV. At the Elekta machine at 18 MV, the superficial dose of a diamond shaped 10 x 10 cm2 field is 3.6% lower than the superficial dose of a regular 10 x 10 cm2 field. This effect is not seen at 6 MV. At the Varian machine, the superficial dose of the diamond shaped field is respectively 3.5 and 14.2% higher than the superficial dose of the regular 10 x 10 cm2 field for 6 MV and 18 MV. Despite the differences measured in build-up dose for single beams between the Elekta and the Varian linear accelerator, there were no measurable differences in superficial dose when a typical IMRT dose plan of 6 MV for a head and neck tumour is executed at the two machines.
authors.affiliation: Ghent University Hospital, De Pintelaan 185, B-9000 Gent, Belgium. Leen@krtkg1.UGent.be
authors.forename: L
authors.initials: L
authors.lastname: Paelinck
authors.forename: C
authors.initials: C
authors.lastname: De Wagter
authors.forename: A
authors.initials: A
authors.lastname: Van Esch
authors.forename: W
authors.initials: W
authors.lastname: Duthoy
authors.forename: T
authors.initials: T
authors.lastname: Depuydt
authors.forename: W
authors.initials: W
authors.lastname: De Neve
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D010315:Particle Accelerators; D017785:Photons; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*; D011882:Radiotherapy, High-Energy / Q000295:instrumentation; D012542:Scattering, Radiation; D014962:X-Ray Film