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Liao Y.-L.,National Cheng Kung University | Lu C.-F.,National Yang Ming University | Sun Y.-N.,National Cheng Kung University | Wu C.-T.,Medical Augmented Reality Research Center | And 4 more authors.
Medical and Biological Engineering and Computing | Year: 2011

In neurosurgery, cranial incisions during craniotomy can be recovered by cranioplasty-a surgical operation using cranial implants to repair skull defects. However, surgeons often encounter difficulties when grafting prefabricated cranial plates into defective areas, since a perfect match to the cranial incision is difficult to achieve. Previous studies using mirroring technique, surface interpolation, or deformed template had limitations in skull reconstruction to match the patient's original appearance. For this study, we utilized low-resolution and high-resolution computed tomography images from the patient to repair skull defects, whilst preserving the original shape. Since the accuracy of skull reconstruction was associated with the partial volume effects in the low-resolution images and the percentage of the skull defect in the high-resolution images, the low-resolution images with intact skull were resampled and thresholded followed by active contour model to suppress partial volume artifacts. The resulting low-resolution images were registered with the high-resolution ones, which exhibited different percentages of cranial defect, to extract the incised cranial part. Finally, mesh smoothing refined the three-dimensional model of the cranial defect. Simulation results indicate that the reconstruction was 93.94% accurate for a 20% skull material removal, and 97.76% accurate for 40% skull material removal. Experimental results demonstrate that the proposed algorithm effectively creates a customized implant, which can readily be used in cranioplasty. © 2010 International Federation for Medical and Biological Engineering. Source

Lee J.-D.,Chang Gung University | Huang C.-H.,Chang Gung University | Huang T.-C.,Chang Gung University | Hsieh H.-Y.,Chang Gung University | And 2 more authors.
Expert Systems with Applications | Year: 2012

This study proposes a cranial augmented-reality (AR) system which characterizes on performing image-to-patient registration using only natural facial features. Its hardware includes only three calibrated CCD cameras but any commercial spatial digitizing devices or artificial skin markers. Two of the cameras are mounted together to form a stereo-vision system, while the third camera moves freely and captures real-time images for AR-fusion display. The facial surface of a patient is first reconstructed by stereo vision. Meanwhile, another facial surface is reconstructed from preoperative computed tomography (CT) images of the patient. A iterative closest point (ICP)-based algorithm is then used to register the two facial data sets, which transfers the anatomical information from the CT images to the physical space. Since the natural of stereo-vision reconstruction usually accompanies with noisy data, the conventional ICP also suffers from its inherent local-minimum problem. Therefore, we propose an improved ICP which embeds a weighting and perturbing strategy to increase robustness and the ability of noise resistance. As a result, with a seamless integration among the preoperative CT images, the patient, the stereo-vision cameras, and the movable camera, an immersive medical AR environment based on a markerless image-to-patient registration is thus accomplished. © 2011 Elsevier Ltd. All rights reserved. Source

Essomba T.,Medical Augmented Reality Research Center | Wu C.-T.,Medical Augmented Reality Research Center | Lee S.-T.,Chang Gung Memorial Hospital | Kuo C.-H.,National Taiwan University of Science and Technology
Mechanisms and Machine Science | Year: 2016

The present paper introduces the mechanical design of a robotic manipulator for craniotomy application considering its kinematic and force transmission ability. The craniotomy is a surgical technique that allows the surgeon to access the patient’s brain by drilling and cutting the skull. The technical requirements of this application are explained. A dedicated mechanical architecture is proposed. This serial spherical arm is analysed in terms of kinematic and force transmission. An optimal mechanism is selected, designed and its actuator are selected to with respect to the identified performances. The global design of the manipulator is analysed and adjusted to reduce the structural deformation. © Springer International Publishing Switzerland 2016. Source

Lee H.-C.,Chang Gung University | Lee J.-D.,Chang Gung University | Lee S.-T.,Medical Augmented Reality Research Center | Wu C.-T.,Medical Augmented Reality Research Center
2015 IEEE International Conference on Consumer Electronics - Taiwan, ICCE-TW 2015 | Year: 2015

The paper presents a novel scheme that uses a projector to project a corrected CT image on the craniofacial surface for augmented reality visualization. The deformation of the projected image due to curved surface can be successful recovered via homography projection correction. The experimental result that shows the superior performance of this work is also included. © 2015 IEEE. Source

Liao Y.-L.,National Cheng Kung University | Liao Y.-L.,National Yang Ming University | Lu C.-F.,National Yang Ming University | Wu C.-T.,Medical Augmented Reality Research Center | And 6 more authors.
Medical and Biological Engineering and Computing | Year: 2013

In cranioplasty, neurosurgeons use bone grafts to repair skull defects. To ensure the protection of intracranial tissues and recover the original head shape for aesthetic purposes, a custom-made pre-fabricated prosthesis must match the cranial incision as closely as possible. In our previous study (Liao et al. in Med Biol Eng Comput 49:203-211, 2011), we proposed an algorithm consisting of the 2D snake and image registration using the patient's own diagnostic low-resolution and defective high-resolution computed tomography (CT) images to repair the impaired skull. In this study, we developed a 3D multigrid snake and employed multiresolution image registration to improve the computational efficiency. After extracting the defect portion images, we designed an image-trimming process to remove the bumped inner margin that can facilitate the placement of skull implants without manual trimming during surgery. To evaluate the performance of the proposed algorithm, a set of skull phantoms were manufactured to simulate six different conditions of cranial defects, namely, unilateral, bilateral, and cross-midline defects with 20 or 40 % skull defects. The overall image processing time in reconstructing the defect portion images can be reduced from 3 h to 20 min, as compared with our previous method. Furthermore, the reconstruction accuracies using the 3D multigrid snake were superior to those using the 2D snake. © 2012 International Federation for Medical and Biological Engineering. Source

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