Adaptation of the CVT algorithm for catheter optimization in high dose rate brachytherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• High dose rate (HDR) brachytherapy requires precise catheter placement for effective tumor coverage and minimal dose to organs at risk.
• Optimizing catheter number and position is crucial for treatment planning but can be computationally intensive.

Purpose of the Study:

• To present an innovative, simple, and fast method for optimizing catheter number and position in prostate and breast HDR brachytherapy.
• To evaluate the method's efficiency and robustness for both arbitrary and template-free implant techniques.

Main Methods:

• Adapted the 2D Centroidal Voronoi Tessellations (CVT) algorithm for uniform catheter distribution within the planning target volume.
• Integrated the inverse planning simulated annealing algorithm (IPSA) for catheter optimization and treatment plan generation.
• Validated the method using clinical cases for prostate and breast HDR brachytherapy, assessing dosimetric parameters and robustness to implantation errors.

Main Results:

• Treatment plans with equivalent or better dose distributions were achieved using fewer catheters (down to 12 for prostate and breast).
• Plans with nine or fewer catheters were deemed clinically unacceptable based on key dosimetric indices (V100, D90).
• The method demonstrated robustness to implantation errors up to 3 mm and achieved clinically acceptable planning times (90 seconds for ten plans).

Conclusions:

• A simple, fast, and efficient method for optimizing catheter number and position in interstitial HDR brachytherapy has been developed.
• The method is robust for both prostate and breast HDR brachytherapy and offers acceptable computation times for clinical application.
• The algorithm holds potential for integration with real-time guidance systems, such as 3D ultrasound, for enhanced brachytherapy planning.