Optimizing robot motion for robotic ultrasound-guided radiation therapy

Area of Science:

• Robotics in Medicine
• Medical Imaging
• Radiation Oncology

Background:

• Active compensation of target motion is crucial for robotic radiation therapy.
• Real-time volumetric ultrasound imaging offers a non-ionizing method for tracking abdominal organ motion.
• Robotic arms can enable flexible ultrasound probe placement during treatment fractions.

Purpose of the Study:

• To develop and evaluate an optimized motion coordination strategy for robotic systems used in radiation therapy with integrated ultrasound.
• To assess the feasibility and impact on treatment time of using a kinematically redundant robot for ultrasound probe manipulation to minimize beam blocking.
• To investigate the application of a generalized traveling salesman problem approach for optimizing the coordinated motion of treatment delivery and ultrasound probe robots.

Main Methods:

• Proposed an optimization approach based on the generalized traveling salesman problem for coordinating two robots: one for beam delivery and one for ultrasound probe holding.
• Utilized a kinematically redundant robot to maintain ultrasound probe pose while adjusting for beam path clearance.
• Compared heuristic and approximation algorithms for solving the complex optimization problem, applying the model to a prostate treatment scenario.

Main Results:

• Integration of the ultrasound probe-holding robot is feasible within radiation therapy workflows.
• The optimized coordination resulted in an acceptable overhead in overall treatment time, less than 4% for clinically realistic robot velocities.
• This approach provides continuous, volumetric, and non-ionizing organ motion tracking, offering advantages over periodic X-ray-based methods.

Conclusions:

• Coordinated robotic motion optimization allows for the integration of real-time ultrasound organ motion tracking in radiation therapy.
• The proposed method effectively minimizes beam blocking and treatment time overhead.
• This technology enhances radiation therapy precision and safety through superior motion compensation.