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Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
Real-time motion-adaptive delivery (MAD) using binary MLC: II. Rotational beam (tomotherapy) delivery
1TomoTherapy Incorporated, 1240 Deming Way Madison, WI 53717, USA. wlu@tomotherapy.com
Physics in Medicine and Biology
|November 4, 2008
Summary
This study introduces a novel software solution for real-time motion compensation in TomoTherapy, enabling accurate radiation delivery by adapting planned treatment sequences to tumor movement. The motion-adaptive delivery (MAD) technique effectively reduces dose errors, even with irregular breathing patterns.
Area of Science:
- Medical Physics
- Radiation Oncology
- Image-Guided Radiation Therapy
Background:
- TomoTherapy delivery relies on pre-planned sinograms for radiation delivery.
- Tumor motion during treatment can lead to significant dose inaccuracies.
- Existing motion compensation methods may require hardware modifications or complex dynamic multi-leaf collimator (MLC) adjustments.
Purpose of the Study:
- To develop and validate a software-based, real-time motion compensation technique for helical TomoTherapy.
- To enable accurate dose delivery without altering the TomoTherapy hardware or workflow.
- To simplify motion compensation by requiring only instantaneous tumor positions.
Main Methods:
- A novel motion-adaptive delivery (MAD) technique was developed, re-using planned sinograms by shuffling projections and leaf sequences.
- Longitudinal tumor motion was compensated by executing projections out of order based on real-time tumor position.
- Transverse motion was managed by adjusting leaf open times for the selected projection.
- The technique was tested with various sinograms, including patient-specific lung cancer data, under different respiratory patterns.
Main Results:
- The MAD technique demonstrated excellent agreement between delivered and planned doses, confirmed by DVH and dose profile analysis.
- Dose errors remained well below established clinical criteria (3 mm and 3%) for regular and minor irregular respiration.
- The method proved effective even for irregular breathing with missing cycles, showing potential for motion margin reduction.
- No significant hot or cold spots were observed in the delivered dose distributions.
Conclusions:
- The developed software solution provides effective real-time motion compensation for helical TomoTherapy.
- The motion-adaptive delivery (MAD) technique simplifies implementation by not requiring hardware changes or dynamic MLC adjustments.
- This approach significantly improves dose accuracy and has the potential to reduce planning margins, enhancing treatment efficacy for moving tumors.
