title: Wide dynamic dose range of VIPAR polymer gel dosimetry.
abstract: In this work the extent of the linear dose response and the dynamic dose range of N-vinylpyrrolidone-argon based (VIPAR) polymer gels were investigated. VIPAR gels were irradiated using a 6 MV linear accelerator up to 60 Gy and a Nucletron microSelectron 192Ir HDR brachytherapy source to much higher doses to cover a dose range of two orders of magnitude. They were then MR scanned at 1.5 T to obtain T2-maps. VIPAR gel measurements obtained from the two irradiation regimes were calibrated against ion chamber measurements and dose calculations derived using the AAPM TG-43 protocol respectively. A satisfying agreement between the calibration results derived using the 6 MV x-rays and the 192Ir source was found for doses up to 60 Gy, implying that the response of the VIPAR gels is independent of photon energy and dose rate. A linear R2 dose response up to approximately 40 Gy and a dynamic dose range up to at least approximately 250 Gy were observed. VIPAR gel dose measurements derived using the monoexponentially fitted brachytherapy calibration data were found to be quite accurate.
authors.affiliation: Physics Department, University of Athens, Panepistimioupolis, Ilisia, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Kipouros
authors.forename: E
authors.initials: E
authors.lastname: Pappas
authors.forename: P
authors.initials: P
authors.lastname: Baras
authors.forename: D
authors.initials: D
authors.lastname: Hatzipanayoti
authors.forename: P
authors.initials: P
authors.lastname: Karaiskos
authors.forename: L
authors.initials: L
authors.lastname: Sakelliou
authors.forename: P
authors.initials: P
authors.lastname: Sandilos
authors.forename: I
authors.initials: I
authors.lastname: Seimenis
mesh_terms: D000465:Algorithms; D001128:Argon; D001918:Brachytherapy / Q000379:methods*; D002138:Calibration; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D008279:Magnetic Resonance Imaging; D010315:Particle Accelerators; D011145:Polyvinyls
chemical_list: D007496:Iridium Radioisotopes; D011145:Polyvinyls; D001128:Argon