Fractionated Stereotactic Intensity-Modulated Radiotherapy for Large Brain Metastases: Comprehensive Analyses of...

Area of Science:

• Radiation Oncology
• Medical Physics
• Neurology

Background:

• Fractionated stereotactic radiotherapy (SRT) is used for brain metastases (BMs).
• Brain necrosis (BN) is a potential complication of SRT.
• Identifying dosimetric predictors of BN is crucial for treatment planning.

Purpose of the Study:

• To investigate dosimetric predictors of brain necrosis (BN) in patients undergoing fractionated stereotactic radiotherapy (SRT).
• To analyze the relationship between dose-volume parameters and BN incidence in brain metastases treatment.

Main Methods:

• Multivariate logistic models were used to analyze dosimetric predictors in patients receiving fractionated SRT for BMs.
• Normal brain volume receiving biologically equivalent doses (VxxEQD2) was calculated.
• Analysis focused on five- and ten-fraction SRT protocols.

Main Results:

• Higher incidence of symptomatic BN was observed with larger V50EQD2, V55EQD2, and V60EQD2 in five- and ten-fraction SRT groups.
• Specific thresholds for V55EQD2 (>30 cc) and V60EQD2 (>20 cc) were associated with increased BN risk.
• These findings were significant after excluding three-fraction SRT groups.

Conclusions:

• Larger V55EQD2 and V60EQD2 are significant predictors of brain necrosis in five- or ten-fraction SRT.
• Biologically high doses to normal brain tissue may increase BN incidence.
• Minimizing planning target volume margins is recommended to reduce BN risk.