title: Quality assurance for the clinical implementation of kilovoltage intrafraction monitoring for prostate cancer VMAT.
abstract: OBJECTIVE
  Kilovoltage intrafraction monitoring (KIM) is a real-time 3D tumor monitoring system for cancer radiotherapy. KIM uses the commonly available gantry-mounted x-ray imager as input, making this method potentially more widely available than dedicated real-time 3D tumor monitoring systems. KIM is being piloted in a clinical trial for prostate cancer patients treated with VMAT (NCT01742403). The purpose of this work was to develop clinical process and quality assurance (QA) practices for the clinical implementation of KIM.
  
  
  METHODS
  Informed by and adapting existing guideline documents from other real-time monitoring systems, KIM-specific QA practices were developed. The following five KIM-specific QA tests were included: (1) static localization accuracy, (2) dynamic localization accuracy, (3) treatment interruption accuracy, (4) latency measurement, and (5) clinical conditions accuracy. Tests (1)-(4) were performed using KIM to measure static and representative patient-derived prostate motion trajectories using a 3D programmable motion stage supporting an anthropomorphic phantom with implanted gold markers to represent the clinical treatment scenario. The threshold for system tolerable latency is <1 s. The tolerances for all other tests are that both the mean and standard deviation of the difference between the programmed trajectory and the measured data are <1 mm. The (5) clinical conditions accuracy test compared the KIM measured positions with those measured by kV/megavoltage (MV) triangulation from five treatment fractions acquired in a previous pilot study.
  
  
  RESULTS
  For the (1) static localization, (2) dynamic localization, and (3) treatment interruption accuracy tests, the mean and standard deviation of the difference are <1.0 mm. (4) The measured latency is 350 ms. (5) For the tests with previously acquired patient data, the mean and standard deviation of the difference between KIM and kV/MV triangulation are <1.0 mm.
  
  
  CONCLUSIONS
  Clinical process and QA practices for the safe clinical implementation of KIM, a novel real-time monitoring system using commonly available equipment, have been developed and implemented for prostate cancer VMAT.
authors.affiliation: School of Medicine, University of Sydney, NSW 2006, Australia and School of Physics, University of Sydney, NSW 2006, Australia.
authors.forename: J A
authors.initials: JA
authors.lastname: Ng
authors.affiliation: School of Physics, University of Sydney, NSW 2006, Australia and Northern Sydney Cancer Centre, Royal North Shore Hospital, NSW 2065, Australia.
authors.forename: J T
authors.initials: JT
authors.lastname: Booth
authors.affiliation: School of Medicine, University of Sydney, NSW 2006, Australia.
authors.forename: R T
authors.initials: RT
authors.lastname: O'Brien
authors.affiliation: School of Medicine, University of Sydney, NSW 2006, Australia and Northern Sydney Cancer Centre, Royal North Shore Hospital, NSW 2065, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Colvill
authors.affiliation: School of Medicine, University of Sydney, NSW 2006, Australia.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Oncology, Aarhus University Hospital, Nørrebrogade 44, Aarhus C 8000, Denmark.
authors.forename: P R
authors.initials: PR
authors.lastname: Poulsen
authors.affiliation: School of Medicine, University of Sydney, NSW 2006, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Keall
mesh_terms: D000465:Algorithms; D002986:Clinical Trials as Topic; D006801:Humans; D008297:Male; D009068:Movement; D010865:Pilot Projects; D011336:Probability; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011785:Quality Assurance, Health Care; D011878:Radiotherapy / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D015203:Reproducibility of Results; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods