title: Characterization of a synthetic single crystal diamond detector for dosimetry in spatially fractionated synchrotron x-ray fields.
abstract: OBJECTIVE
  Modern radiotherapy modalities often use small or nonstandard fields to ensure highly localized and precise dose delivery, challenging conventional clinical dosimetry protocols. The emergence of preclinical spatially fractionated synchrotron radiotherapies with high dose-rate, sub-millimetric parallel kilovoltage x-ray beams, has pushed clinical dosimetry to its limit. A commercially available synthetic single crystal diamond detector designed for small field dosimetry has been characterized to assess its potential as a dosimeter for synchrotron microbeam and minibeam radiotherapy.
  
  
  METHODS
  Experiments were carried out using a synthetic diamond detector on the imaging and medical beamline (IMBL) at the Australian Synchrotron. The energy dependence of the detector was characterized by cross-referencing with a calibrated ionization chamber in monoenergetic beams in the energy range 30-120 keV. The dose-rate dependence was measured in the range 1-700 Gy/s. Dosimetric quantities were measured in filtered white beams, with a weighted mean energy of 95 keV, in broadbeam and spatially fractionated geometries, and compared to reference dosimeters.
  
  
  RESULTS
  The detector exhibits an energy dependence; however, beam quality correction factors (kQ) have been measured for energies in the range 30-120 keV. The kQ factor for the weighted mean energy of the IMBL radiotherapy spectrum, 95 keV, is 1.05 ± 0.09. The detector response is independent of dose-rate in the range 1-700 Gy/s. The percentage depth dose curves measured by the diamond detector were compared to ionization chambers and agreed to within 2%. Profile measurements of microbeam and minibeam arrays were performed. The beams are well resolved and the full width at halfmaximum agrees with the nominal width of the beams. The peak to valley dose ratio (PVDR) calculated from the profiles at various depths in water agrees within experimental error with PVDR calculations from Gafchromic film data.
  
  
  CONCLUSIONS
  The synthetic diamond detector is now well characterized and will be used to develop an experimental dosimetry protocol for spatially fractionated synchrotron radiotherapy.
authors.affiliation: Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia.
authors.forename: Jayde
authors.initials: J
authors.lastname: Livingstone
authors.affiliation: Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia and CSIRO Manufacturing, Clayton South, Victoria 3169, Australia.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Stevenson
authors.affiliation: Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085, Australia.
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Butler
authors.affiliation: Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Häusermann
authors.affiliation: Equipe d'accueil Rayonnement Synchrotron et Recherche Médicale, Université Grenoble Alpes, European Synchrotron Radiation Facility - ID17, Grenoble 38043, France and Centre Hospitalier Universitaire de Grenoble, Grenoble 38043, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Adam
mesh_terms: D002138:Calibration; D004867:Equipment Design; D016014:Linear Models; D017785:Photons; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011878:Radiotherapy / Q000295:instrumentation / Q000379:methods; D017356:Synchrotrons; D014867:Water; D014965:X-Rays
chemical_list: D014867:Water