The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Brian R Davidson - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic tracking in image guided laparoscopic surgery comparison with optical tracking and feasibility study of a combined Laparoscope and laparoscopic ultrasound system
Medical Physics, 2018Co-Authors: Guofang Xiao, Ester Bonmati, Joe Evans, John H. Hipwell, Daniil I. Nikitichev, Stephen A. Thompson, Kurinchi Selvan Gurusamy, David J. Hawkes, Sebastien Ourselin, Brian R DavidsonAbstract:Purpose In image-guided laparoscopy, optical tracking is commonly employed, but electromagnetic (EM) systems have been proposed in the literature. In this paper, we provide a thorough comparison of EM and optical tracking systems for use in image-guided laparoscopic surgery and a feasibility study of a combined, EM-tracked Laparoscope and laparoscopic ultrasound (LUS) image guidance system. Methods We first assess the tracking accuracy of a Laparoscope with two optical trackers tracking retroreflective markers mounted on the shaft and an EM tracker with the sensor embedded at the proximal end, using a standard evaluation plate. We then use a stylus to test the precision of position measurement and accuracy of distance measurement of the trackers. Finally, we assess the accuracy of an image guidance system comprised of an EM-tracked Laparoscope and an EM-tracked LUS probe. Results In the experiment using a standard evaluation plate, the two optical trackers show less jitter in position and orientation measurement than the EM tracker. Also, the optical trackers demonstrate better consistency of orientation measurement within the test volume. However, their accuracy of measuring relative positions decreases significantly with longer distances whereas the EM tracker's performance is stable; at 50 mm distance, the RMS errors for the two optical trackers are 0.210 and 0.233 mm, respectively, and it is 0.214 mm for the EM tracker; at 250 mm distance, the RMS errors for the two optical trackers become 1.031 and 1.178 mm, respectively, while it is 0.367 mm for the EM tracker. In the experiment using the stylus, the two optical trackers have RMS errors of 1.278 and 1.555 mm in localizing the stylus tip, and it is 1.117 mm for the EM tracker. Our prototype of a combined, EM-tracked Laparoscope and LUS system using representative calibration methods showed a RMS point localization error of 3.0 mm for the Laparoscope and 1.3 mm for the LUS probe, the lager error of the former being predominantly due to the triangulation error when using a narrow-baseline stereo Laparoscope. Conclusions The errors incurred by optical trackers, due to the lever-arm effect and variation in tracking accuracy in the depth direction, would make EM-tracked solutions preferable if the EM sensor is placed at the proximal end of the Laparoscope.
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Electromagnetic tracking in image‐guided laparoscopic surgery: Comparison with optical tracking and feasibility study of a combined Laparoscope and laparoscopic ultrasound system
Medical Physics, 2018Co-Authors: Guofang Xiao, Ester Bonmati, Joe Evans, John H. Hipwell, Daniil I. Nikitichev, Stephen A. Thompson, Kurinchi Selvan Gurusamy, David J. Hawkes, Sebastien Ourselin, Brian R DavidsonAbstract:In image-guided laparoscopy, optical tracking is commonly employed, but electromagnetic (EM) systems have been proposed in the literature. In this paper, we provide a thorough comparison of EM and optical tracking systems for use in image-guided laparoscopic surgery and a feasibility study of a combined, EM-tracked Laparoscope and laparoscopic ultrasound (LUS) image guidance system. We first assess the tracking accuracy of a Laparoscope with two optical trackers tracking retroreflective markers mounted on the shaft and an EM tracker with the sensor embedded at the proximal end, using a standard evaluation plate. We then use a stylus to test the precision of position measurement and accuracy of distance measurement of the trackers. Finally, we assess the accuracy of an image guidance system comprised of an EM-tracked Laparoscope and an EM-tracked LUS probe. In the experiment using a standard evaluation plate, the two optical trackers show less jitter in position and orientation measurement than the EM tracker. Also, the optical trackers demonstrate better consistency of orientation measurement within the test volume. However, their accuracy of measuring relative positions decreases significantly with longer distances whereas the EM tracker's performance is stable; at 50 mm distance, the RMS errors for the two optical trackers are 0.210 and 0.233 mm, respectively, and it is 0.214 mm for the EM tracker; at 250 mm distance, the RMS errors for the two optical trackers become 1.031 and 1.178 mm, respectively, while it is 0.367 mm for the EM tracker. In the experiment using the stylus, the two optical trackers have RMS errors of 1.278 and 1.555 mm in localizing the stylus tip, and it is 1.117 mm for the EM tracker. Our prototype of a combined, EM-tracked Laparoscope and LUS system using representative calibration methods showed a RMS point localization error of 3.0 mm for the Laparoscope and 1.3 mm for the LUS probe, the lager error of the former being predominantly due to the triangulation error when using a narrow-baseline stereo Laparoscope. The errors incurred by optical trackers, due to the lever-arm effect and variation in tracking accuracy in the depth direction, would make EM-tracked solutions preferable if the EM sensor is placed at the proximal end of the Laparoscope. © 2018 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
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on pattern selection for Laparoscope calibration
Proceedings of SPIE, 2017Co-Authors: Stephen A. Thompson, David J. Hawkes, Brian R Davidson, Sebastien Ourselin, Yannic Meuer, Eddie Edwards, Joao Ramalhinho, Maria Robu, Danail Stoyanov, Matthew J ClarksonAbstract:Camera calibration is a key requirement for augmented reality in surgery. Calibration of Laparoscopes provides two challenges that are not sufficiently addressed in the literature. In the case of stereo Laparoscopes the small distance (less than 5mm) between the channels means that the calibration pattern is an order of magnitude more distant than the stereo separation. For Laparoscopes in general, if an external tracking system is used, hand-eye calibration is difficult due to the long length of the Laparoscope. Laparoscope intrinsic, stereo and hand-eye calibration all rely on accurate feature point selection and accurate estimation of the camera pose with respect to a calibration pattern. We compare 3 calibration patterns, chessboard, rings, and AprilTags. We measure the error in estimating the camera intrinsic parameters and the camera poses. Accuracy of camera pose estimation will determine the accuracy with which subsequent stereo or hand-eye calibration can be done. We compare the results of repeated real calibrations and simulations using idealised noise, to determine the expected accuracy of different methods and the sources of error. The results do indicate that feature detection based on rings is more accurate than a chessboard, however this doesn’t necessarily lead to a better calibration. Using a grid with identifiable tags enables detection of features nearer the image boundary, which may improve calibration.
Mike Nguyen - One of the best experts on this subject based on the ideXlab platform.
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comparison of six display modes for a multi resolution foveated Laparoscope
Surgical Endoscopy and Other Interventional Techniques, 2019Co-Authors: Sangyoon Lee, Hong Hua, Mike Nguyen, Allan J HamiltonAbstract:Background To overcome the field of view and ergonomic limitations of standard Laparoscopes, we are developing a multi-resolution foveated Laparoscope that can simultaneously obtain both wide- and zoomed-in-view images through a single scope. To facilitate the effective access to the dual views of images with different resolution and field coverage acquired by our Laparoscope, six different display modes have been developed. Each of the six display modes has inherent advantages and disadvantages. This study compares the six display modes through a human-subject experiment, which was conducted with an emulated Laparoscope using a 4K camera. Methods Twenty-four subjects without medicine background performed three evaluation trials of a touching task with each of the display modes. Various objective measurements including task completion time, the number of collisions, gaze position, and tooltip position, and subjective preference for the display modes were recorded. Results For all the measurements except for task completion time and moving speed of tooltip, there were statistically significant differences among the display modes. Although the focus plus warped context view mode was selected as one of the least preferred modes, it showed the best task performance. Conclusions The unblocked wide context view was useful to provide a situational awareness even when it was severely distorted in some of the display modes, and information continuity played an important role in improving task performance. Moreover, the position change of viewing window coupled to the location of region of interest helped improve task performance, by providing an additional cue for spatial awareness.
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characterization and in vivo evaluation of a multi resolution foveated Laparoscope for minimally invasive surgery
Biomedical Optics Express, 2014Co-Authors: Yi Qin, Hong Hua, Mike NguyenAbstract:The state-of-the-art Laparoscope lacks the ability to capture high-magnification and wide-angle images simultaneously, which introduces challenges when both close- up views for details and wide-angle overviews for orientation are required in clinical practice. A multi-resolution foveated Laparoscope (MRFL) which can provide the surgeon both high-magnification close-up and wide-angle images was proposed to address the limitations of the state-of-art surgical Laparoscopes. In this paper, we present the overall system design from both clinical and optical system perspectives along with a set of experiments to characterize the optical performances of our prototype system and describe our preliminary in-vivo evaluation of the prototype with a pig model. The experimental results demonstrate that at the optimum working distance of 120mm, the high-magnification probe has a resolution of 6.35lp/mm and image a surgical area of 53 × 40mm2; the wide-angle probe provides a surgical area coverage of 160 × 120mm2 with a resolution of 2.83lp/mm. The in-vivo evaluation demonstrates that MRFL has great potential in clinical applications for improving the safety and efficiency of the laparoscopic surgery.
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Multiresolution foveated Laparoscope with high resolvability
Optics letters, 2013Co-Authors: Yi Qin, Hong Hua, Mike NguyenAbstract:A key limitation of the state-of-the-art Laparoscopes for minimally invasive surgery is the tradeoff between the field of view and spatial resolution in a single-view camera system. As such, surgical procedures are usually performed at a zoomed-in view, which limits the surgeon’s ability to see much outside the immediate focus of interest and causes a situational awareness challenge. We proposed a multiresolution foveated Laparoscope (MRFL) aiming to address this limitation. The MRFL is able to simultaneously capture wide-angle overview and high-resolution images in real time; it can scan and engage the high-resolution images to any subregion of the entire surgical field in analogy to the fovea of human eye. The MRFL is able to render equivalently 10 million pixel resolution with a low data bandwidth requirement. The system has a large working distance (WD) from 80 to 180 mm. The spatial resolvability is about 45 μm in the object space at an 80 mm WD, while the resolvability of a conventional Laparoscope is about 250 μm at a typically 50 mm surgical distance.
Nancy J. Hogle - One of the best experts on this subject based on the ideXlab platform.
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initial trial of a stereoscopic insertable remotely controlled camera for minimal access surgery
Surgical Endoscopy and Other Interventional Techniques, 2010Co-Authors: Dennis L. Fowler, Tejas Nadkarni, Peter K. Allen, Nancy J. HogleAbstract:Background Although video-laparoscopy has enabled successful minimal access surgery, the nature of the technology causes many troublesome limitations: (1) the fulcrum effect of the insertion site through the abdominal wall limits the angle of view, (2) the camera operator must use counterintuitive movements, (3) the Laparoscope occupies an incision which otherwise could be used for an instrument, and (4) the Laparoscope provides a two-dimensional image. Methods A stereoscopic, insertable, remotely controlled camera was developed to overcome the limitations imposed by traditional video-laparoscopy. Additional functionality included digital zoom, picture-in-picture (PIP), and tracking capability for autonomous function of the camera. Four surgical tasks were performed twice in a porcine model, once using the insertable camera and once using a standard video-Laparoscope setup for visualization. Running the bowel, simulated laparoscopic appendectomy, laparoscopic nephrectomy, and laparoscopic suturing and tying were measured for time, blood loss, and complications. Digital zoom, PIP, and the ability of the computer to move the camera to track a marked instrument were subjectively evaluated. Results The tasks were aborted in one animal because a new three-dimensional (3D) display could not be synchronized with the camera and in another animal because a motor in the camera failed. The tasks were all completed twice in two animals. The mean time was less for all procedures using the insertable camera. There was no significant blood loss and there were no complications. Digital zoom and PIP displaying both a close-up and a panoramic view were subjectively felt to improve visualization by all observers. The computer could reliably move the camera to track a marked instrument to keep it in the center of the field of view. Conclusions This preliminary proof-of-concept study suggests that a stereoscopic, insertable, remotely controlled camera may provide better visualization during minimal access surgery by overcoming many of the limitations of
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Initial trial of a stereoscopic, insertable, remotely controlled camera for minimal access surgery
Surgical Endoscopy, 2009Co-Authors: Dennis L. Fowler, Tie Hu, Tejas Nadkarni, Peter K. Allen, Nancy J. HogleAbstract:Background Although video-laparoscopy has enabled successful minimal access surgery, the nature of the technology causes many troublesome limitations: (1) the fulcrum effect of the insertion site through the abdominal wall limits the angle of view, (2) the camera operator must use counterintuitive movements, (3) the Laparoscope occupies an incision which otherwise could be used for an instrument, and (4) the Laparoscope provides a two-dimensional image. Methods A stereoscopic, insertable, remotely controlled camera was developed to overcome the limitations imposed by traditional video-laparoscopy. Additional functionality included digital zoom, picture-in-picture (PIP), and tracking capability for autonomous function of the camera. Four surgical tasks were performed twice in a porcine model, once using the insertable camera and once using a standard video-Laparoscope setup for visualization. Running the bowel, simulated laparoscopic appendectomy, laparoscopic nephrectomy, and laparoscopic suturing and tying were measured for time, blood loss, and complications. Digital zoom, PIP, and the ability of the computer to move the camera to track a marked instrument were subjectively evaluated. Results The tasks were aborted in one animal because a new three-dimensional (3D) display could not be synchronized with the camera and in another animal because a motor in the camera failed. The tasks were all completed twice in two animals. The mean time was less for all procedures using the insertable camera. There was no significant blood loss and there were no complications. Digital zoom and PIP displaying both a close-up and a panoramic view were subjectively felt to improve visualization by all observers. The computer could reliably move the camera to track a marked instrument to keep it in the center of the field of view. Conclusions This preliminary proof-of-concept study suggests that a stereoscopic, insertable, remotely controlled camera may provide better visualization during minimal access surgery by overcoming many of the limitations of video-laparoscopy.
Guofang Xiao - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic tracking in image guided laparoscopic surgery comparison with optical tracking and feasibility study of a combined Laparoscope and laparoscopic ultrasound system
Medical Physics, 2018Co-Authors: Guofang Xiao, Ester Bonmati, Joe Evans, John H. Hipwell, Daniil I. Nikitichev, Stephen A. Thompson, Kurinchi Selvan Gurusamy, David J. Hawkes, Sebastien Ourselin, Brian R DavidsonAbstract:Purpose In image-guided laparoscopy, optical tracking is commonly employed, but electromagnetic (EM) systems have been proposed in the literature. In this paper, we provide a thorough comparison of EM and optical tracking systems for use in image-guided laparoscopic surgery and a feasibility study of a combined, EM-tracked Laparoscope and laparoscopic ultrasound (LUS) image guidance system. Methods We first assess the tracking accuracy of a Laparoscope with two optical trackers tracking retroreflective markers mounted on the shaft and an EM tracker with the sensor embedded at the proximal end, using a standard evaluation plate. We then use a stylus to test the precision of position measurement and accuracy of distance measurement of the trackers. Finally, we assess the accuracy of an image guidance system comprised of an EM-tracked Laparoscope and an EM-tracked LUS probe. Results In the experiment using a standard evaluation plate, the two optical trackers show less jitter in position and orientation measurement than the EM tracker. Also, the optical trackers demonstrate better consistency of orientation measurement within the test volume. However, their accuracy of measuring relative positions decreases significantly with longer distances whereas the EM tracker's performance is stable; at 50 mm distance, the RMS errors for the two optical trackers are 0.210 and 0.233 mm, respectively, and it is 0.214 mm for the EM tracker; at 250 mm distance, the RMS errors for the two optical trackers become 1.031 and 1.178 mm, respectively, while it is 0.367 mm for the EM tracker. In the experiment using the stylus, the two optical trackers have RMS errors of 1.278 and 1.555 mm in localizing the stylus tip, and it is 1.117 mm for the EM tracker. Our prototype of a combined, EM-tracked Laparoscope and LUS system using representative calibration methods showed a RMS point localization error of 3.0 mm for the Laparoscope and 1.3 mm for the LUS probe, the lager error of the former being predominantly due to the triangulation error when using a narrow-baseline stereo Laparoscope. Conclusions The errors incurred by optical trackers, due to the lever-arm effect and variation in tracking accuracy in the depth direction, would make EM-tracked solutions preferable if the EM sensor is placed at the proximal end of the Laparoscope.
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Electromagnetic tracking in image‐guided laparoscopic surgery: Comparison with optical tracking and feasibility study of a combined Laparoscope and laparoscopic ultrasound system
Medical Physics, 2018Co-Authors: Guofang Xiao, Ester Bonmati, Joe Evans, John H. Hipwell, Daniil I. Nikitichev, Stephen A. Thompson, Kurinchi Selvan Gurusamy, David J. Hawkes, Sebastien Ourselin, Brian R DavidsonAbstract:In image-guided laparoscopy, optical tracking is commonly employed, but electromagnetic (EM) systems have been proposed in the literature. In this paper, we provide a thorough comparison of EM and optical tracking systems for use in image-guided laparoscopic surgery and a feasibility study of a combined, EM-tracked Laparoscope and laparoscopic ultrasound (LUS) image guidance system. We first assess the tracking accuracy of a Laparoscope with two optical trackers tracking retroreflective markers mounted on the shaft and an EM tracker with the sensor embedded at the proximal end, using a standard evaluation plate. We then use a stylus to test the precision of position measurement and accuracy of distance measurement of the trackers. Finally, we assess the accuracy of an image guidance system comprised of an EM-tracked Laparoscope and an EM-tracked LUS probe. In the experiment using a standard evaluation plate, the two optical trackers show less jitter in position and orientation measurement than the EM tracker. Also, the optical trackers demonstrate better consistency of orientation measurement within the test volume. However, their accuracy of measuring relative positions decreases significantly with longer distances whereas the EM tracker's performance is stable; at 50 mm distance, the RMS errors for the two optical trackers are 0.210 and 0.233 mm, respectively, and it is 0.214 mm for the EM tracker; at 250 mm distance, the RMS errors for the two optical trackers become 1.031 and 1.178 mm, respectively, while it is 0.367 mm for the EM tracker. In the experiment using the stylus, the two optical trackers have RMS errors of 1.278 and 1.555 mm in localizing the stylus tip, and it is 1.117 mm for the EM tracker. Our prototype of a combined, EM-tracked Laparoscope and LUS system using representative calibration methods showed a RMS point localization error of 3.0 mm for the Laparoscope and 1.3 mm for the LUS probe, the lager error of the former being predominantly due to the triangulation error when using a narrow-baseline stereo Laparoscope. The errors incurred by optical trackers, due to the lever-arm effect and variation in tracking accuracy in the depth direction, would make EM-tracked solutions preferable if the EM sensor is placed at the proximal end of the Laparoscope. © 2018 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
Hong Hua - One of the best experts on this subject based on the ideXlab platform.
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comparison of six display modes for a multi resolution foveated Laparoscope
Surgical Endoscopy and Other Interventional Techniques, 2019Co-Authors: Sangyoon Lee, Hong Hua, Mike Nguyen, Allan J HamiltonAbstract:Background To overcome the field of view and ergonomic limitations of standard Laparoscopes, we are developing a multi-resolution foveated Laparoscope that can simultaneously obtain both wide- and zoomed-in-view images through a single scope. To facilitate the effective access to the dual views of images with different resolution and field coverage acquired by our Laparoscope, six different display modes have been developed. Each of the six display modes has inherent advantages and disadvantages. This study compares the six display modes through a human-subject experiment, which was conducted with an emulated Laparoscope using a 4K camera. Methods Twenty-four subjects without medicine background performed three evaluation trials of a touching task with each of the display modes. Various objective measurements including task completion time, the number of collisions, gaze position, and tooltip position, and subjective preference for the display modes were recorded. Results For all the measurements except for task completion time and moving speed of tooltip, there were statistically significant differences among the display modes. Although the focus plus warped context view mode was selected as one of the least preferred modes, it showed the best task performance. Conclusions The unblocked wide context view was useful to provide a situational awareness even when it was severely distorted in some of the display modes, and information continuity played an important role in improving task performance. Moreover, the position change of viewing window coupled to the location of region of interest helped improve task performance, by providing an additional cue for spatial awareness.
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characterization and in vivo evaluation of a multi resolution foveated Laparoscope for minimally invasive surgery
Biomedical Optics Express, 2014Co-Authors: Yi Qin, Hong Hua, Mike NguyenAbstract:The state-of-the-art Laparoscope lacks the ability to capture high-magnification and wide-angle images simultaneously, which introduces challenges when both close- up views for details and wide-angle overviews for orientation are required in clinical practice. A multi-resolution foveated Laparoscope (MRFL) which can provide the surgeon both high-magnification close-up and wide-angle images was proposed to address the limitations of the state-of-art surgical Laparoscopes. In this paper, we present the overall system design from both clinical and optical system perspectives along with a set of experiments to characterize the optical performances of our prototype system and describe our preliminary in-vivo evaluation of the prototype with a pig model. The experimental results demonstrate that at the optimum working distance of 120mm, the high-magnification probe has a resolution of 6.35lp/mm and image a surgical area of 53 × 40mm2; the wide-angle probe provides a surgical area coverage of 160 × 120mm2 with a resolution of 2.83lp/mm. The in-vivo evaluation demonstrates that MRFL has great potential in clinical applications for improving the safety and efficiency of the laparoscopic surgery.
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Multiresolution foveated Laparoscope with high resolvability
Optics letters, 2013Co-Authors: Yi Qin, Hong Hua, Mike NguyenAbstract:A key limitation of the state-of-the-art Laparoscopes for minimally invasive surgery is the tradeoff between the field of view and spatial resolution in a single-view camera system. As such, surgical procedures are usually performed at a zoomed-in view, which limits the surgeon’s ability to see much outside the immediate focus of interest and causes a situational awareness challenge. We proposed a multiresolution foveated Laparoscope (MRFL) aiming to address this limitation. The MRFL is able to simultaneously capture wide-angle overview and high-resolution images in real time; it can scan and engage the high-resolution images to any subregion of the entire surgical field in analogy to the fovea of human eye. The MRFL is able to render equivalently 10 million pixel resolution with a low data bandwidth requirement. The system has a large working distance (WD) from 80 to 180 mm. The spatial resolvability is about 45 μm in the object space at an 80 mm WD, while the resolvability of a conventional Laparoscope is about 250 μm at a typically 50 mm surgical distance.
