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Quality control procedures for dynamic treatment delivery techniques involving couch motion
Victoria Y Yu1, Benjamin P Fahimian1, Lei Xing1
1Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305-5847.
Medical Physics
|August 4, 2014
Summary
This study validates quality control for dynamic radiation therapy delivery, ensuring precise couch motion accuracy. Results show the Varian TrueBeam™ system achieves excellent geometric and dosimetric fidelity for complex treatments.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Technology
Background:
- Dynamic treatment delivery in radiation oncology requires precise patient positioning.
- Synchronizing couch motion with gantry and multileaf collimator (MLC) presents unique quality control challenges.
- Ensuring geometric and dosimetric fidelity is crucial for effective and safe cancer treatment.
Purpose of the Study:
- To introduce and demonstrate quality control (QC) procedures for dynamic treatment delivery involving synchronous couch motion.
- To evaluate the positional accuracy, velocity constancy, and accuracy of dynamic couch motion under load.
- To assess the geometric accuracy of complex dynamic treatment trajectories.
Main Methods:
- Developed custom XML scripts to control Varian TrueBeam™ STx axes in Developer Mode.
- Implemented tests for positional accuracy, velocity constancy, and accuracy of dynamic couch motion.
- Utilized radiographic film and electronic portal imaging device (EPID) to capture delivered dose patterns.
- Devised a test for geometric accuracy over complex dynamic trajectories.
Main Results:
- Couch translational accuracy in dynamic mode was 0.01 cm.
- Rotational accuracy was within 0.3°, with 0.04 cm axis displacement.
- Dose intensity profiles showed velocity constancy and accuracy deviations below 3%.
- Overall translational accuracy for complex MLC and couch motions was within 0.06 cm.
Conclusions:
- The Varian TrueBeam™ system, in Developer Mode, demonstrates high geometric and dosimetric fidelity for dynamic treatment delivery.
- The validated QC procedures are effective for ensuring the accuracy of advanced radiotherapy techniques.
- The findings support the clinical implementation of dynamic couch motion in radiation therapy.
