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Trajectory log file sensitivity: A critical analysis using DVH and EPID.

Wui Ann Woon1,2, Paul B Ravindran2,3, Piyasiri Ekayanake2

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PubMed
Summary
This summary is machine-generated.

Trajectory log files effectively detect multileaf collimator (MLC) positioning errors in radiation therapy. This quality assurance method correlates well with dose errors, improving treatment accuracy.

Keywords:
Dose errorIntensity-modulated radiation therapyMultileaf collimatorTrajectory log filesVolumetric arc therapy

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Area of Science:

  • Medical Physics
  • Radiation Oncology
  • Quality Assurance

Background:

  • Quality assurance in radiation therapy is crucial for patient safety.
  • Trajectory log files offer a novel method for monitoring treatment delivery accuracy.
  • Electronic portal imaging device (EPID) measurements are a standard for verification.

Purpose of the Study:

  • To evaluate the sensitivity of trajectory log file analysis in detecting MLC and gantry positioning errors.
  • To compare log file-based quality assurance with EPID measurements using the 3%/3mm criteria.
  • To analyze the correlation between gamma passing rates and dose errors.

Main Methods:

  • An in-house program modified treatment plans using log file data to recalculate dose distributions.
  • Recalculated dose-volume histograms (DVHs) were compared to original DVHs.
  • Differences in DVH were compared with EPID dosimetry.

Main Results:

  • A strong positive linear relationship was observed between MLC positioning errors and dose errors for IMRT and VMAT plans.
  • Gantry positioning errors had minimal impact on VMAT delivery.
  • A significant positive correlation was found between VMAT gamma passing rates (3%/3mm) and mean DVH dose error (r=0.59, P<0.001).

Conclusions:

  • Trajectory log files are sensitive to systematic MLC errors and random errors in dose delivery.
  • The study successfully analyzed the correlation between gamma passing rates and DVH metrics.
  • Log file analysis provides a valuable tool for quality assurance in radiation therapy.