title: Sensitivity variation of doped Fricke gel irradiated with monochromatic synchrotron X rays between 33.5 and 80 keV.
abstract: An experimental binary radiotherapy proposes the concomitant use of a high-Z compound and synchrotron X rays for enhancing radiation dose selectively in tumours by a photoelectric effect. This study aimed at measuring the resulting dose enhancement in irradiated material. A doped Fricke gel dosemeter model was manufactured with 10 mg ml(-1) of iodine (Telebrix) or barium (Micropaque). Samples were irradiated with a monochromatic synchrotron beam at 33.5, 50, 65 and 80 keV. The ensuing enhancement of the sensitivity of the dosemeter was derived from the nuclear magnetic resonance relaxation rates measured at different X-ray doses. Our results demonstrate (1) the preservation of a linear relationship between relaxation rates and X-ray doses for dosemeters doped with high-Z atoms and (2) a clear energy-dependent sensitivity enhancement for barium-doped Fricke gels. This enhancement was neither reproducible with iodinated compounds nor clearly related to the expected dose enhancement factor. However 1% barium sulphate in the gel could significantly improve the gel's response when it was irradiated by low-energy X rays.
authors.affiliation: INSERM-U647 Rayonnement synchrotron et recherche médicale and ID17 Biomedical Beamline of the European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, F-38043 Grenoble Cedex, France. stephanie_corde@yaoo.fr
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Corde
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Adam
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Biston
authors.forename: Aurélie
authors.initials: A
authors.lastname: Joubert
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Charvet
authors.forename: François
authors.initials: F
authors.lastname: Estève
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Le Bas
authors.forename: Hélène
authors.initials: H
authors.lastname: Elleaume
authors.forename: Jacques
authors.initials: J
authors.lastname: Balosso
mesh_terms: D001466:Barium Sulfate / Q000737:chemistry; D002138:Calibration; D004307:Dose-Response Relationship, Radiation; D005782:Gels; D007477:Ions; D007483:Iothalamic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009369:Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D017356:Synchrotrons; D014965:X-Rays
chemical_list: D005782:Gels; D007477:Ions; D007483:Iothalamic Acid; D001466:Barium Sulfate; C002587:ioxitalamic acid