Real-time dynamic MLC tracking for inversely optimized arc radiotherapy

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Accurate radiotherapy delivery is crucial for effective cancer treatment.
• Target motion during treatment can compromise dose accuracy.

Purpose of the Study:

• To evaluate the efficacy of MLC tracking for motion compensation in inversely optimized arc radiotherapy.
• To assess the impact of target displacement size and leaf trajectory angle on dosimetric accuracy.

Main Methods:

• An MLC-tracking algorithm adjusted MLC positions in real-time based on optical positioning data.
• Two treatment plans (45 and 90 degrees collimator angles) were delivered with simulated target displacements (5-25 mm).
• Dosimetric measurements were performed using a Delta(4)(R) device.

Main Results:

• MLC tracking achieved a >98% pass rate for 3%/3 mm gamma index criteria across all displacement sizes.
• Without motion compensation, average pass rates dropped to 75% and 70% for 25 mm displacement.
• Dosimetric accuracy with MLC tracking was independent of displacement magnitude and leaf trajectory angle.

Conclusions:

• MLC tracking enhances the accuracy of inversely optimized arc radiotherapy delivery.
• The technique effectively mitigates the impact of target motion on dose delivery accuracy.
• MLC tracking offers a robust solution for motion management in arc radiotherapy.