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Verification of Commercial Respiratory Tracking System Using Scintillation Screen

S Lim

S Lim*, Department of Radiation Oncology, Kosin University College of Medicine, Busan

SU-E-J-164 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall

Purpose: The accuracy of the tracking system is critical for the result of four-dimensional radiation therapy. The objective of this study is to propose the method of verifying the accuracy of respiratory tracking system.
Methods: The scintillation screen and the light marker between the transparent acrylic plates were designed to move according to the pre-recorded respiratory organ motion of volunteers. A vertical circle photon beam with 3 cm diameters from the cyberknife unit was planned to track the motion of the scintillation screen with the plates. In dark room, the CCD camera outside of the phantom captured the scintillation from the screen and the light marker in 30 frames per second when the photon beam was incident. The pictures were captured by the CCD camera were analyzed frame by frame, and the discrepancy between the scintillating circle on the scintillation screen and the light marker depending on the time was measured. The discrepancy of the motions of the delivered photon beam and the light marker was analyzed.
Results: In the preliminary study, the maximum discrepancy was measured less than 1.5 mm in normal breathing pattern as the manufacturer specified it.
Conclusions: As the speed of the motion was increased, the discrepancy between the position of the beam and internal marker increased. However, the error was clinically acceptable. The further study will be performed for the irregular respiratory motion patterns.

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