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Factor 10 Expedience of Monthly Linac Quality Assurance via an Ion Chamber Array and Automation Scripts
Lawrie B Skinner1, Yong Yang1, Annie Hsu1
1Department of Radiation Oncology, Stanford University, Palo Alto, CA, USA.
Technology in Cancer Research & Treatment
|November 12, 2019
Summary
Streamlining medical linear accelerator quality assurance (QA) with an automated ion chamber array workflow reduces testing time from 5 hours to 30 minutes. This method enhances accuracy and efficiency for essential radiotherapy QA tasks.
Area of Science:
- Medical Physics
- Radiotherapy Technology
- Quality Assurance
Background:
- Monthly quality assurance (QA) of medical linear accelerators is crucial for safe and accurate radiotherapy.
- Current QA methods are time-consuming, requiring significant physics resources.
- Previous institutional methods for mechanical and dosimetric QA took approximately 5 hours.
Purpose of the Study:
- To develop an improved workflow for medical linear accelerator QA that is faster and more accurate.
- To reduce the time burden of routine QA tests.
- To minimize error pathways in the QA process.
Main Methods:
- Combined a commercial ion chamber array (IC profiler) with automation scripts for consolidated QA.
- Measured various parameters including output, flatness, symmetry, jaw positions, and constancy tests.
- Implemented workflow on a standard Varian linac, adaptable to other C-arm accelerators.
Main Results:
- Reduced QA time to 30 minutes, covering 20 of 26 TG-142 recommended tests.
- Improved precision in beam profile, energy constancy, field size, and jaw position tests.
- Observed output constancy uncertainties within TG-142 guidelines (0.3% for photons, 0.5% for electrons).
Conclusions:
- The implemented equipment, procedure, and scripts significantly reduce the time required for routine linear accelerator QA.
- The new workflow generally improves precision compared to previous methods.
- This approach offers a more efficient and accurate solution for essential radiotherapy QA.
