title: Optimizing the modified microdosimetric kinetic model input parameters for proton and4He ion beam therapy application.
abstract: Models able to predict relative biological effectiveness (RBE) values are necessary for an accurate determination of the biological effect with proton and4He ion beams. This is particularly important when including RBE calculations in treatment planning studies comparing biologically optimized proton and4He ion beam plans. In this work, we have tailored the predictions of the modified microdosimetric kinetic model (MKM), which is clinically applied for carbon ion beam therapy in Japan, to reproduce RBE with proton and4He ion beams. We have tuned the input parameters of the MKM, i.e. the domain and nucleus radii, reproducing an experimental database of initial RBE data for proton and He ion beams. The modified MKM, with the best fit parameters obtained, has been used to reproduce in vitro cell survival data in clinically-relevant scenarios. A satisfactory agreement has been found for the studied cell lines, A549 and RENCA, with the mean absolute survival variation between the data and predictions within 2% and 5% for proton and4He ion beams, respectively. Moreover, a sensitivity study has been performed varying the domain and nucleus radii and the quadratic parameter of the photon response curve. The promising agreement found in this work for the studied clinical-like scenarios supports the usage of the modified MKM for treatment planning studies in proton and4He ion beam therapy.
authors.affiliation: Medical Physics Unit, CNAO Foundation, Via Strada Campeggi 53, I-27100 Pavia, Italy. Heidelberg Ion Beam Therapy Center, Im Neuenheimer Feld 450, D-69120 Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mairani
authors.forename: G
authors.initials: G
authors.lastname: Magro
authors.forename: T
authors.initials: T
authors.lastname: Tessonnier
authors.forename: T T
authors.initials: TT
authors.lastname: Böhlen
authors.forename: S
authors.initials: S
authors.lastname: Molinelli
authors.forename: A
authors.initials: A
authors.lastname: Ferrari
authors.forename: K
authors.initials: K
authors.lastname: Parodi
authors.forename: J
authors.initials: J
authors.lastname: Debus
authors.forename: T
authors.initials: T
authors.lastname: Haberer
mesh_terms: D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D061766:Proton Therapy; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D012062:Relative Biological Effectiveness
chemical_list: D006371:Helium