SU-E-J-166: Development of Real-Time Motion Verification System for Respiratory-Gated Radiotherapy

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Image Guidance

Background:

• Real-time position management (RPM) systems are crucial for precise radiotherapy.
• Phase-based gating in radiotherapy requires accurate verification of patient motion.
• Current quality assurance methods for RPM may not fully capture real-time motion variations.

Purpose of the Study:

• To develop an on-line quality assurance tool for real-time position management (RPM) phase-based gated radiotherapy.
• To verify the positional reproducibility of patient breathing between CT simulation and treatment using a novel system.

Main Methods:

• Developed a real-time motion verification system (RMVS) using infrared reflective markers and a stereo camera system.
• Extracted 4D reference lines from 4D-CT data for phase-resolved motion analysis.
• Integrated RMVS with RPM for real-time comparison of patient's position against 4D reference lines.

Main Results:

• The RMVS demonstrated compatibility with RPM and detected motion errors in phantom studies.
• Mean absolute errors (MAE) ranged from 1.0 mm (ideal/cycle change) to 9.8 ± 1.2 mm (10.0 mm baseline shift).
• The system showed MAE between 1.5 ± 1.1 mm and 4.9 ± 2.5 mm for varying amplitudes.

Conclusions:

• The developed RMVS is competent in detecting phase-matching errors between real-time patient motion and 4D-CT references.
• The system can serve as an effective on-line quality assurance tool for RPM phase-based radiotherapy.
• This technology enhances the precision and safety of image-guided radiotherapy treatments.