Beam orientation optimization in intensity-modulated radiation treatment planning

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Imaging

Background:

• Optimizing beam directions is crucial in radiation therapy, particularly for intensity modulated radiation therapy (IMRT).
• The coupled nature of beam directions and intensity profiles complicates traditional optimization methods in IMRT.
• Iterative or stochastic methods require frequent beam profile recalculation during beam direction optimization.

Purpose of the Study:

• To develop and report an effective algorithm for optimizing gantry angles in IMRT.
• To decouple the optimization of gantry angles and beam profiles for improved computational efficiency.
• To evaluate the performance of a fast filtered backprojection (FBP) method for beam orientation optimization.

Main Methods:

• Gantry angles and beam profiles (beamlet weights) were treated as separate variable groups.
• Simulated annealing was employed for sampling gantry angles and optimizing beam profiles.
• A fast filtered backprojection (FBP) method was used for beam profile calculation.
• Relative importance factors were integrated into the objective function to balance target coverage and sensitive structure sparing.

Main Results:

• The algorithm successfully optimized gantry angles and beam profiles by minimizing the objective function.
• Simulated annealing demonstrated effectiveness for beam orientation optimization using the FBP method.
• The approach yielded optimal beam orientations and profiles based on the defined objective function.

Conclusions:

• The proposed method effectively optimizes gantry angles and beam profiles independently in IMRT.
• This approach shows significant potential for enhancing treatment planning in IMRT applications.
• The algorithm offers a promising strategy for improving the precision and efficiency of radiation therapy planning.