Electromagnetic-guided dynamic multileaf collimator tracking enables motion management for intensity-modulated arc...

Area of Science:

• Radiation Oncology
• Medical Physics
• Image-Guided Therapy

Background:

• Intensity-modulated arc therapy (IMAT) offers high-dose conformity and efficient delivery.
• Managing intrafraction motion remains a significant challenge for IMAT efficacy.
• Current clinical practices struggle to accurately treat moving targets during IMAT.

Purpose of the Study:

• To develop and evaluate an electromagnetically guided dynamic multileaf collimator (DMLC) tracking system.
• To investigate DMLC tracking as a method for treating moving targets during IMAT.
• To assess the dosimetric accuracy and efficiency of DMLC-IMAT for mobile tumors.

Main Methods:

• A real-time 3D DMLC tracking system was integrated with a linear accelerator.
• The system dynamically adjusted leaf positions based on electromagnetic target position data and IMAT plans.
• Dosimetric measurements were performed on a motion platform simulating patient movement, comparing DMLC tracking, no tracking, and static conditions using a gamma-test.

Main Results:

• With DMLC tracking, only 1.6% (lung) and 1.2% (prostate) of dose points failed the 3-mm/3% gamma-test.
• Without tracking, failure rates increased significantly to 34% (lung) and 14% (prostate).
• Treatment delivery time remained consistent with or without DMLC tracking.

Conclusions:

• Electromagnetic-guided DMLC target tracking represents a novel approach for IMAT.
• DMLC tracking demonstrated significantly superior dose distributions for moving targets compared to non-tracking methods.
• This technology enhances treatment accuracy for moving targets in IMAT without sacrificing treatment efficiency.