title: Assessment and Implications of Scattered Microbeam and Broadbeam Synchrotron Radiation for Bystander Effect Studies.
abstract: Synchrotron radiation is an excellent tool for investigating bystander effects in cell and animal models because of the well-defined and controllable configuration of the beam. Although synchrotron radiation has many advantages for such studies compared to conventional radiation, the contribution of dose exposure from scattered radiation nevertheless remains a source of concern. Therefore, the influence of scattered radiation on the detection of bystander effects induced by synchrotron radiation in biological in vitro models was evaluated. Radiochromic XRQA2 film-based dosimetry was employed to measure the absorbed dose of scattered radiation in cultured cells at various distances from a field exposed to microbeam radiotherapy and broadbeam X-ray radiation. The level of scattered radiation was dependent on the distance, dose in the target zone and beam mode. The number of γ-H2AX foci in cells positioned at the same target distances was measured and used as a biodosimeter to evaluate the absorbed dose. A correlation of absorbed dose values measured by the physical and biological methods was identified. The γ-H2AX assay successfully quantitated the scattered radiation in the range starting from 10 mGy and its contribution to the observed radiation-induced bystander effect.
authors.affiliation: a  Molecular Radiation Biology Laboratory, Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia;|b  Sir Peter MacCallum Department of Oncology, the University of Melbourne, Melbourne, VIC, Australia;
authors.forename: Pavel
authors.initials: P
authors.lastname: Lobachevsky
authors.affiliation: c  MIMR-PHI Institute of Medical Research and.|e  College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, Australia;
authors.forename: Alesia
authors.initials: A
authors.lastname: Ivashkevich
authors.affiliation: c  MIMR-PHI Institute of Medical Research and.|d  Hudson Institute, Centre for Innate Immunity and Infectious Diseases, Clayton, VIC, Australia;|f  Monash University, Department of Molecular and Translational Sciences, Clayton, VIC, Australia;
authors.forename: Helen B
authors.initials: HB
authors.lastname: Forrester
authors.affiliation: g  CSIRO Division of Materials Science and Engineering, Clayton, VIC, Australia;|h  Australian Synchrotron, Clayton, VIC, Australia; and.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Stevenson
authors.affiliation: g  CSIRO Division of Materials Science and Engineering, Clayton, VIC, Australia;
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hall
authors.affiliation: c  MIMR-PHI Institute of Medical Research and.|d  Hudson Institute, Centre for Innate Immunity and Infectious Diseases, Clayton, VIC, Australia;|f  Monash University, Department of Molecular and Translational Sciences, Clayton, VIC, Australia;
authors.forename: Carl N
authors.initials: CN
authors.lastname: Sprung
authors.affiliation: a  Molecular Radiation Biology Laboratory, Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia;|b  Sir Peter MacCallum Department of Oncology, the University of Melbourne, Melbourne, VIC, Australia;|i  Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Martin
mesh_terms: D024201:Bystander Effect / Q000502:physiology* / Q000528:radiation effects*; D002478:Cells, Cultured; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005373:Film Dosimetry; D006801:Humans; D008214:Lymphocytes / Q000502:physiology* / Q000528:radiation effects*; D011829:Radiation Dosage; D012542:Scattering, Radiation; D017356:Synchrotrons / Q000295:instrumentation*