SBRT planning for spinal metastasis: indications from a large multicentric study

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Investigated dosimetric variability in spine stereotactic body radiation therapy (SBRT) planning across multiple centers.
• Aimed to identify crowd knowledge-based solutions to reduce planning inconsistencies.

Purpose of the Study:

• To assess the impact of knowledge sharing on spine SBRT planning quality.
• To identify key factors influencing dosimetric outcomes in spine SBRT.

Main Methods:

• 48 planners from 38 centers planned two spinal cases with specific prescription dose (PD) and planning target volume (PTV) coverage requirements.
• Dose constraints for the spinal cord and esophagus were defined; re-optimization was performed for non-compliant plans using peer results.
• Statistical analysis correlated dosimetric results with planning parameters, and a quality index (QI) was developed.

Main Results:

• Initially, 12.5% of plans failed to meet protocol requirements; this improved to 98% after re-optimization, demonstrating the value of knowledge sharing.
• Significant correlations were found between the homogeneity index (HI) and PTV coverage, and between HI and spinal cord sparing in specific cases.
• Multileaf collimator leaf thickness correlated with spinal cord sparing, and planner skill significantly impacted the quality index (QI) despite similar technology.

Conclusions:

• Both technological factors and planner expertise are essential for optimizing spine SBRT plans.
• Collaborative knowledge sharing effectively guided planners toward achieving desired plan objectives in spine SBRT.