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The Journal of the Korean Society for Therapeutic Radiology and Oncology 2006;24(4): 300-308. |
Patient Setup Aid with Wireless CCTV System in Radiation Therapy |
Yang Kyun Park, Sung Whan Ha, Sung Joon Ye, Woong Cho, Jong Min Park, Suk Won Park, Soon Nyung Huh |
1Department of Radiation Applying Life Science, Seoul National University Graduate School, Korea. 2Department of Radiation Oncology, Seoul National University College of Medicine, Korea. 3Institute of Radiation Medicine, Medical Research Center, Seoul National University, Korea. meditronic@freechal.com 4Department of Radiation Oncology, Chung-Ang University College of Medicine, Korea. 5Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea. |
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ABSTRACT |
PURPOSE: To develop a wireless CCTV system in semi-beam's eye view (BEV) to monitor daily patient setup in radiation therapy.
MATERIALS AND METHODS: In order to get patient images in semi-BEV, CCTV cameras are installed in a custom-made acrylic applicator below the treatment head of a linear accelerator. The images from the cameras are transmitted via radio frequency signal (~2.4 GHz and 10 mW RF output). An expected problem with this system is radio frequency interference, which is solved utilizing RF shielding with Cu foils and median filtering software. The images are analyzed by our custom-made software. In the software, three anatomical landmarks in the patient surface are indicated by a user, then automatically the 3 dimensional structures are obtained and registered by utilizing a localization procedure consisting mainly of stereo matching algorithm and Gauss-Newton optimization. This algorithm is applied to phantom images to investigate the setup accuracy.
Respiratory gating system is also researched with real-time image processing. A line-laser marker projected on a patient's surface is extracted by binary image processing and the breath pattern is calculated and displayed in real-time.
RESULTS: More than 80% of the camera noises from the linear accelerator are eliminated by wrapping the camera with copper foils. The accuracy of the localization procedure is found to be on the order of 1.5+/-0.7 mm with a point phantom and sub-millimeters and degrees with a custom-made head/neck phantom. With line-laser marker, real-time respiratory monitoring is possible in the delay time of ~0.17 sec.
CONCLUSION: The wireless CCTV camera system is the novel tool which can monitor daily patient setups. The feasibility of respiratory gating system with the wireless CCTV is hopeful. |
Key Words:
IGRT, Patient setup, Wireless CCTV, Image processing, Stereo matching, Respiratory gating |
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