Effect of different optimization parameters in single isocenter multiple brain metastases radiosurgery

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• Automated treatment planning for multiple brain metastases presents unique challenges compared to traditional methods.
• Understanding optimization parameters and their impact on plan quality is crucial for effective treatment design.

Purpose of the Study:

• To provide a reference for designing multi-metastases treatment plans.
• To define quality endpoints for benchmarking automated planning techniques.

Main Methods:

• Retrospective planning of 183 lesions in 20 patients across four optimization scenarios.
• Evaluation of plan quality using conformity index, gradient index, and normal tissue dose.
• Analysis of parameter variations, lesion number, and beam types.

Main Results:

• Minor plan quality differences observed across scenarios; increased lesions led to higher monitor units and dose to healthy tissue.
• Highly modulated plans showed slightly increased V10% but no increase in monitor units.
• Flattening filter-free (FFF) beams reduced local V12Gy and treatment time by 46%, despite a 13-15% increase in monitor units.

Conclusions:

• No clinically significant parameter differences were found, but dose distribution variations exist.
• Less complex scenarios showed more dose overlap, suggesting complex scenarios might be preferable.
• Quality metrics showed minor differences, but dose distribution nuances warrant consideration.