Technical Report: TG-142 compliant and comprehensive quality assurance tests for respiratory gating

Kyle Woods, Yi Rong

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Purpose: To develop and establish a comprehensive gating commissioning and quality assurance procedure in compliance with TG-142. Methods: Eight Varian TrueBeam Linacs were used for this study. Gating commissioning included an end-to-end test and baseline establishment. The end-to-end test was performed using a CIRS dynamic thoracic phantom with a moving cylinder inside the lung, which was used for carrying both optically simulated luminescence detectors (OSLDs) and Gafchromic EBT2 films while the target is moving, for a point dose check and 2D profile check. In addition, baselines were established for beam-on temporal delay and calibration of the surrogate, for both megavoltage (MV) and kilovoltage (kV) beams. A motion simulation device (MotionSim) was used to provide periodic motion on a platform, in synchronizing with a surrogate motion. The overall accuracy and uncertainties were analyzed and compared. Results: The OSLD readings were within 5% compared to the planned dose (within measurement uncertainty) for both phase and amplitude gated deliveries. Film results showed less than 3% agreement to the predicted dose with a standard sinusoid motion. The gate-on temporal accuracy was averaged at 139�10 ms for MV beams and 92�11 ms for kV beams. The temporal delay of the surrogate motion depends on the motion speed and was averaged at 54.6�3.1 ms for slow, 24.9�2.9 ms for intermediate, and 23.0�20.1 ms for fast speed. Conclusions: A comprehensive gating commissioning procedure was introduced for verifying the output accuracy and establishing the temporal accuracy baselines with respiratory gating. The baselines are needed for routine quality assurance tests, as suggested by TG-142.

Original languageEnglish (US)
Pages (from-to)6488-6497
Number of pages10
JournalMedical Physics
Volume42
Issue number11
DOIs
StatePublished - Nov 1 2015

Keywords

  • calibration of surrogate
  • real-time position management
  • respiratory gating
  • temporal accuracy
  • time delays

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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