SU-E-J-172: Development of a Video Guided Real-Time Patient Motion Monitoring System for Helical Tomotherpay.

Area of Science:

• Medical Physics
• Radiation Oncology
• Image-Guided Therapy

Background:

• Patient motion during radiation therapy can lead to significant dose delivery errors.
• Real-time motion monitoring is crucial for maintaining treatment accuracy in advanced radiotherapy techniques like helical TomoTherapy.

Purpose of the Study:

• To develop and evaluate a video image-guided real-time patient motion monitoring system for helical TomoTherapy (VGRPM-Tomo).
• To assess the clinical utility and performance of the VGRPM-Tomo system using a motion phantom.

Main Methods:

• The VGRPM-Tomo system integrates PC cameras, a control computer with a radiation signal controller, and custom motion analysis software.
• It utilizes real-time frame difference analysis with an exponential weighting filter (EWF) to detect patient movement against a continuously updated background.
• The system synchronizes with the treatment beam trigger and provides audible and visual warnings when motion exceeds predefined criteria (δ_movement).

Main Results:

• The optimal EWF factor (a) for clinical use was determined to be between 0.85 and 0.9.
• The VGRPM-Tomo system successfully detected phantom motion as small as 0.2 cm with a tight δ_movement criterion (0.1% of reference image pixels).
• The overall system response time was measured at an efficient 0.1 seconds.

Conclusions:

• The VGRPM-Tomo system can significantly reduce treatment errors caused by patient motion.
• Implementation of this system is expected to enhance the accuracy of dose delivery in helical TomoTherapy (HD).
• The developed technology is protected by a Korean patent.