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Accurate calibration of a stereo‐vision system in image‐guided radiotherapy
Author(s) -
Liu Dezhi,
Li Shidong
Publication year - 2006
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2362873
Subject(s) - computer vision , artificial intelligence , calibration , coordinate system , computer science , image registration , stereo imaging , camera resectioning , medical imaging , mathematics , image (mathematics) , statistics
Image‐guided radiotherapy using a three‐dimensional (3D) camera as the on‐board surface imaging system requires precise and accurate registration of the 3D surface images in the treatment machine coordinate system. Two simple calibration methods, an analytical solution as three‐point matching and a least‐squares estimation method as multipoint registration, were introduced to correlate the stereo‐vision surface imaging frame with the machine coordinate system. Both types of calibrations utilized 3D surface images of a calibration template placed on the top of the treatment couch. Image transformational parameters were derived from corresponding 3D marked points on the surface images to their given coordinates in the treatment room coordinate system. Our experimental results demonstrated that both methods had provided the desired calibration accuracy of 0.5 mm . The multipoint registration method is more robust particularly for noisy 3D surface images. Both calibration methods have been used as our weekly QA tools for a 3D image‐guided radiotherapy system.