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Target Contour Consistency During Magnetic Resonance-Guided Online Adaptive Stereotactic Body Radiation Therapy
Suzanne Kirby1, Kiana Rahimi1, William Song1
1Department of Radiation Oncology, Virginia Commonwealth University Health System, Richmond, Virginia.
Advances in Radiation Oncology
|April 17, 2025
Summary
Primary physicians showed greater gross tumor volume (GTV) changes than covering physicians in adaptive magnetic resonance-guided stereotactic body radiation therapy (MRgSBRT). Contouring support resources had minimal impact on GTV delineation consistency.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Cancer Treatment
Background:
- Adaptive magnetic resonance-guided stereotactic body radiation therapy (MRgSBRT) requires precise daily target volume recontouring.
- Gross tumor volume (GTV) contouring is often performed by covering physicians (CPs) less familiar with the case than primary physicians (PPs).
Purpose of the Study:
- To assess GTV contouring consistency between PPs and CPs in MRgSBRT.
- To analyze the impact of contouring support resources on GTV delineation accuracy.
Main Methods:
- Analysis of 302 MRgSBRT fractions from 59 patients treated between 2021-2023.
- Comparison of GTV volume changes between PPs and CPs.
- Evaluation of three contouring support resources: slice count, external software, and volume difference alerts.
Main Results:
- CPs exhibited significantly smaller mean absolute percent GTV volume changes (4.6%) compared to PPs (11.1%).
- Significant differences were noted for pancreas, liver, and lymph node GTVs, with PPs showing larger variations.
- No significant impact of contouring support resources on GTV differences was observed.
Conclusions:
- PPs demonstrate greater variability in GTV contouring compared to CPs across most tumor sites.
- Current contouring support resources appear to have limited effect on improving consistency.
- Further research is needed to enhance contouring support methods for adaptive MRgSBRT.
