title: Microdosimetric assessment of the radiation quality of a therapeutic proton beam: comparison between numerical simulation and experimental measurements.
abstract: Using protons for the treatment of ocular melanoma (especially of posterior pole tumours), the radiation quality of the beam must be precisely assessed to preserve the vision and to minimise the damage to healthy tissue. The radiation quality of a therapeutic proton beam at the Centre Antoine Lacassagne in Nice (France) was measured using microdosimetric techniques, i.e. a miniaturised version of a tissue-equivalent proportional counter. Measurements were performed in a 1-µm site at different depths in a Lucite phantom. Experimental data showed a significant increase in the beam quality at the distal edge of the spread-out Bragg peak (SOBP). In this paper, the numerical simulation of the experimental setup is done with the FLUKA Monte Carlo radiation transport code. The calculated microdosimetric spectra are compared with the measured ones at different depths in tissue for a monoenergetic proton beam (E=62 MeV) and for a modulated SOBP. Numerically and experimentally predicted relative biological effectiveness values are in good agreement. The calculated frequency-averaged and dose-averaged lineal energy mean values are consistent with measured data.
authors.affiliation: Department Health and Environment, Austrian Institute of Technology, A-1220 Vienna, Austria. sofia.rollet@ait.ac.at
authors.forename: S
authors.initials: S
authors.lastname: Rollet
authors.forename: P
authors.initials: P
authors.lastname: Colautti
authors.forename: B
authors.initials: B
authors.lastname: Grosswendt
authors.forename: J
authors.initials: J
authors.lastname: Herault
authors.forename: M
authors.initials: M
authors.lastname: Wind
authors.forename: E
authors.initials: E
authors.lastname: Gargioni
authors.forename: P
authors.initials: P
authors.lastname: Beck
authors.forename: M
authors.initials: M
authors.lastname: Latocha
authors.forename: D
authors.initials: D
authors.lastname: Moro
mesh_terms: D003198:Computer Simulation; D005134:Eye Neoplasms / Q000503:physiopathology* / Q000532:radiotherapy*; D006801:Humans; D008545:Melanoma / Q000503:physiopathology* / Q000532:radiotherapy*; D008954:Models, Biological; D061766:Proton Therapy; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D016896:Treatment Outcome; D011522:Protons
chemical_list: D011522:Protons