Deformable image registration for composite planned doses during adaptive radiation therapy.
Joshua Torchia1, Michael Velec1
1Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
Journal of Medical Imaging and Radiation Sciences
|January 13, 2024
Summary
Deformable image registration (DIR) accurately aligns radiotherapy scans, revealing significant dose differences compared to standard methods. Using DIR for adaptive re-planning improves total dose accuracy and aids in precise re-contouring for better patient outcomes.
Area of Science:
- Medical Physics
- Radiotherapy
- Image Analysis
Background:
- Anatomic changes during radiotherapy necessitate adaptive re-planning, creating dual planning datasets and dose record uncertainty.
- Accurate total dose records are crucial for evaluating treatment efficacy and patient outcomes.
Purpose of the Study:
- To investigate the impact of deformable image registration (DIR) on calculating total planned dose distributions in adaptive radiotherapy.
- To compare dose accumulation using DIR with standard parameter addition methods.
Main Methods:
- Analyzed data from 15 patients (head-and-neck, lung, sarcoma) requiring re-planning.
- Calculated total planned doses using 'parameter addition' (summing DVH metrics) and 'dose accumulation' (using DIR to align CTs and dose distributions).
- Assessed dose differences (≥100 cGy) for organs-at-risk and attributed variations to registration accuracy or contouring differences.
Main Results:
- DIR achieved high accuracy in aligning repeat CT-simulation images.
- Significant dose differences (≥100 cGy) were observed in 11 of 15 patients when comparing DIR-based dose accumulation with parameter addition.
- Contouring variability accounted for 22 of 41 relevant dose differences; DIR-corrected contours showed reduced variations.
Conclusions:
- Deformable image registration (DIR) is recommended for adaptive radiotherapy re-planning to generate accurate total planned dose records.
- DIR facilitates precise re-contouring and improves the reliability of dose calculations, potentially enhancing clinical outcome understanding.
- DIR revealed substantial dose differences compared to standard clinical methods, altering planned acceptance criteria in some cases.
