Clinical treatment planning optimization by Powell's method for gamma unit treatment system

Area of Science:

• Medical Physics
• Radiotherapy
• Computational Biology

Background:

• Stereotactic radiosurgery (SRS) using gamma units has been a clinical practice for approximately 30 years.
• Current treatment planning relies on time-consuming, iterative trial-and-error methods by physician-physicist teams.
• Existing methods often struggle to achieve optimal treatment plans, particularly concerning isocenter weights and precise target coverage.

Purpose of the Study:

• To present a novel computational optimization method for stereotactic radiosurgery treatment planning.
• To enhance the efficiency and accuracy of treatment plan development for gamma unit systems.
• To improve the conformity of radiation dose distribution to the target volume while considering sensitive tissue protection.

Main Methods:

• Development of a computer-based treatment planning system implementing Powell's optimization algorithm.
• Initial treatment parameters (isocenters, collimator sizes, weights) are roughly estimated by the clinical team.
• The objective function is adaptable to incorporate constraints for protecting critical structures.

Main Results:

• The optimization procedure was tested using initial parameters provided by experienced clinicians and author-generated estimates.
• Dosimetric analysis demonstrated superior high-dose volume conformation to the target volume compared to manually generated treatment plans.
• The automated method achieved excellent agreement between isodose curves and target volume contours.

Conclusions:

• The developed optimization method exhibits rapid convergence and robustness, showing minimal sensitivity to initial parameter variations.
• The system consistently produces treatment plans with excellent conformity of radiation dose to the target.
• Dosimetric outcomes remain largely consistent even with variations in initial parameter configurations, ensuring reliable plan quality.