SU-E-T-607: Determining Critical Objectives and Importance Factors for Prostate IMRT Treatment Planning

Area of Science:

• Radiation Oncology
• Medical Physics
• Computational Biology

Background:

• Prostate intensity-modulated radiation therapy (IMRT) requires complex treatment planning.
• Optimizing multiple objectives is computationally intensive.
• Identifying critical objectives can streamline planning.

Purpose of the Study:

• To identify the most critical optimization objectives in prostate IMRT planning.
• To demonstrate that clinically acceptable treatments can be achieved with fewer objectives and optimized importance factors.
• To enhance computational efficiency in treatment planning.

Main Methods:

• A novel inverse optimization method was developed using historical prostate IMRT treatments.
• Importance factors for candidate objectives were quantified.
• A simplified formulation with critical objectives and inversely optimized importance factors was compared to a comprehensive formulation.

Main Results:

• A treatment plan with 18 objectives was successfully replicated using only six objectives.
• Minimizing mean dose and penalizing dose above 50 Gy were critical for bladder and rectum.
• Minimizing maximum dose was critical for femoral heads; bladder and rectum objectives accounted for >95% of importance.

Conclusions:

• Identifying critical objectives significantly enhances computational efficiency in treatment planning.
• A simplified formulation with inversely optimized importance factors reduces iterative planning.
• This approach offers a more efficient and potentially less error-prone treatment planning process.