title: High resolution 3D imaging of synchrotron generated microbeams.
abstract: OBJECTIVE
  Microbeam radiation therapy (MRT) techniques are under investigation at synchrotrons worldwide. Favourable outcomes from animal and cell culture studies have proven the efficacy of MRT. The aim of MRT researchers currently is to progress to human clinical trials in the near future. The purpose of this study was to demonstrate the high resolution and 3D imaging of synchrotron generated microbeams in PRESAGE® dosimeters using laser fluorescence confocal microscopy.
  
  
  METHODS
  Water equivalent PRESAGE® dosimeters were fabricated and irradiated with microbeams on the Imaging and Medical Beamline at the Australian Synchrotron. Microbeam arrays comprised of microbeams 25-50 μm wide with 200 or 400 μm peak-to-peak spacing were delivered as single, cross-fire, multidirectional, and interspersed arrays. Imaging of the dosimeters was performed using a nikon a1 laser fluorescence confocal microscope.
  
  
  RESULTS
  The spatial fractionation of the MRT beams was clearly visible in 2D and up to 9 mm in depth. Individual microbeams were easily resolved with the full width at half maximum of microbeams measured on images with resolutions of as low as 0.09 μm/pixel. Profiles obtained demonstrated the change of the peak-to-valley dose ratio for interspersed MRT microbeam arrays and subtle variations in the sample positioning by the sample stage goniometer were measured.
  
  
  CONCLUSIONS
  Laser fluorescence confocal microscopy of MRT irradiated PRESAGE® dosimeters has been validated in this study as a high resolution imaging tool for the independent spatial and geometrical verification of MRT beam delivery.
authors.affiliation: Alfred Health Radiation Oncology, The Alfred, Melbourne, Victoria 3004, Australia and School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Gagliardi
authors.affiliation: Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales 2500, Australia.
authors.forename: Iwan
authors.initials: I
authors.lastname: Cornelius
authors.affiliation: Division of Health Sciences, School of Pharmacy and Medical Sciences, The University of South Australia, Adelaide, South Australia 5000, Australia and Division of Information Technology, Engineering and the Environment, Mawson Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia.
authors.forename: Anton
authors.initials: A
authors.lastname: Blencowe
authors.affiliation: School of Applied Sciences and Health Innovations Research Institute, RMIT University, Melbourne, Victoria 3000, Australia.
authors.forename: Rick D
authors.initials: RD
authors.lastname: Franich
authors.affiliation: School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
authors.forename: Moshi
authors.initials: M
authors.lastname: Geso
mesh_terms: D004867:Equipment Design; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods*; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D011878:Radiotherapy / Q000295:instrumentation* / Q000379:methods*; D017356:Synchrotrons / Q000295:instrumentation