SU‐E‐T‐263: Development of a Video Guided Real‐Time Patient Motion Monitoring System

Abstract

Purpose: Using conventional CCD camera systems, we developed a video image guided real‐time patientˈs motion monitoring (VGRPM) system; a motion phantom was used for evaluation of its performance for clinical use. Methods: The VGRPM system consists of three parts: an image acquisition device, a main control computer, and in‐house developed patient motion analysis software. For development of an intelligent patient motion monitoring system that works only during treatment time and for system automation, the system was designed for synchronization with a beam on/off trigger signal. Patient movement during radiation is detected by real‐time frame difference based in‐house developed analysis software. When the error range exceeds the set criteria, (Cmove), a warning message is generated in the form of light and sound. The described procedure repeats automatically for each patient. A motion phantom, which operates by moving a distance of 0.5, 1, and 2 cm for 1 and 2 sec, respectively, was used for evaluation of system performance. We measured optimal Cmove for clinical use, minimum distance, which can be detected in this system, and response time of the whole system. The stability of the system in a linear accelerator unit was evaluated for a period of 6 months. Results: : As a result of the moving phantom test, the Cmove for detection of all simulated phantom motion was determined to be 0.5%. The system can detect phantom motion as small as 0.5 cm. The measured response time from detection of phantom movement to warning signal through video analysis was 0.1 sec. During this testing period, no significant functional disorder was observed. Conclusions: The VGRPM system can contribute to reduction of treatment error by patientˈs motion and increase the accuracy of treatment dose delivery.