Development of a Real-time Patient's Intrafraction Motion Monitoring System During Radiation Treatment

概要

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In high precise conformal radiation therapy, patient's intrafraction motion decreases the accuracy of target coverage and organs at risk sparing. In our study, we designed and developed a new monitoring system for the motion. The system consisted of a web camera and a computer running our in-house software in which template matching algorithms with pre-image processing were implemented. The motion of a marker box on patient was tracked as a surrogate of the motion. The system accuracy was evaluated by employing a respiratory motion phantom. Additionally, the effectiveness of the system was investigated in healthy volunteers, in terms of the results from the differences in the intrafraction motion detectable between the marker positions. The monitoring system could achieve a 1 mm positional accuracy and also 50 msec temporal resolution. The system was found to be within AAPM Task Group 142 tolerance for respiratory-gated radiation therapy. The movement of the marker on the sternum was substantially decreased as compared with the abdomen. The measurement of the motion could be measured using the sternum as a position of the marker box. Our system can manage the intrafraction motion and also enables treatment irradiation to be undertaken with high accuracy.