27 February 2015 Image calibration and registration in cone-beam computed tomogram for measuring the accuracy of computer-aided implant surgery
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Medical radiography is the use of radiation to “see through” a human body without breaching its integrity (surface). With computed tomography (CT)/cone beam computed tomography (CBCT), three-dimensional (3D) imaging can be produced. These imagings not only facilitate disease diagnosis but also enable computer-aided surgical planning/navigation. In dentistry, the common method for transfer of the virtual surgical planning to the patient (reality) is the use of surgical stent either with a preloaded planning (static) like a channel or a real time surgical navigation (dynamic) after registration with fiducial markers (RF). This paper describes using the corner of a cube as a radiopaque fiducial marker on an acrylic (plastic) stent, this RF allows robust calibration and registration of Cartesian (x, y, z)- coordinates for linking up the patient (reality) and the imaging (virtuality) and hence the surgical planning can be transferred in either static or dynamic way. The accuracy of computer-aided implant surgery was measured with reference to coordinates. In our preliminary model surgery, a dental implant was planned virtually and placed with preloaded surgical guide. The deviation of the placed implant apex from the planning was x=+0.56mm [more right], y=- 0.05mm [deeper], z=-0.26mm [more lingual]) which was within clinically 2mm safety range. For comparison with the virtual planning, the physically placed implant was CT/CBCT scanned and errors may be introduced. The difference of the actual implant apex to the virtual apex was x=0.00mm, y=+0.21mm [shallower], z=-1.35mm [more lingual] and this should be brought in mind when interpret the results.
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Walter Y. H. Lam, Walter Y. H. Lam, Henry Y. T. Ngan, Henry Y. T. Ngan, Peter Y. P. Wat, Peter Y. P. Wat, Henry W. K. Luk, Henry W. K. Luk, Tazuko K. Goto, Tazuko K. Goto, Edmond H. N. Pow, Edmond H. N. Pow, "Image calibration and registration in cone-beam computed tomogram for measuring the accuracy of computer-aided implant surgery", Proc. SPIE 9405, Image Processing: Machine Vision Applications VIII, 94050A (27 February 2015); doi: 10.1117/12.2083341; https://doi.org/10.1117/12.2083341

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