Quality assurance for the clinical implementation of kilovoltage intrafraction monitoring for prostate cancer VMAT

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    J. A. Ng, 1] Neuroscience Research Australia, Randwick, Sydney, New South Wales 2031, Australia [2] School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia., AustraliaJ. T. Booth, Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006, Australia, AustraliaR. T. O'Brien, 1] Neuroscience Research Australia, Randwick, Sydney, New South Wales 2031, Australia [2] School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia., AustraliaE. Colvill, 1] Neuroscience Research Australia, Randwick, Sydney, New South Wales 2031, Australia [2] School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia., AustraliaC. Y. Huang, School of Medicine, University of Sydney, NSW 2006, Australia
  • Per Rugaard Poulsen
  • P. J. Keall, 1] Neuroscience Research Australia, Randwick, Sydney, New South Wales 2031, Australia [2] School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia., Australia
Purpose: 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.
Original languageEnglish
Article number111712
JournalMedical Physics
Volume41
Issue number11
Number of pages9
ISSN0094-2405
DOIs
StatePublished - 21 Oct 2014

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