Imperial College London

Dr George Mylonas

Faculty of MedicineDepartment of Surgery & Cancer

Lecturer in Robotics and Technology in Cancer



+44 (0)20 3312 5145george.mylonas Website




Room 5Paterson WingSt Mary's Campus





Publication Type

70 results found

Mylonas GP, Stoyanov D, Darzi A, Yang GZet al., 2007, Assessment of perceptual quality for gaze-contingent motion stabilization in robotic assisted minimally invasive surgery, Pages: 660-667, ISSN: 0302-9743

With the increasing sophistication of surgical robots, the use of motion stabilisation for enhancing the performance of micro-surgical tasks is an actively pursued research topic. The use of mechanical stabilisation devices has certain advantages, in terms of both simplicity and consistency. The technique, however, can complicate the existing surgical workflow and interfere with an already crowded MIS operated cavity. With the advent of reliable vision-based real-time and in situ in vivo techniques on 3D-deformation recovery, current effort is being directed towards the use of optical based techniques for achieving adaptive motion stabilisation. The purpose of this paper is to assess the effect of virtual stabilization on foveal/parafoveal vision during robotic assisted MIS. Detailed psychovisual experiments have been performed. Results show that stabilisation of the whole visual field is not necessary and it is sufficient to perform accurate motion tracking and deformation compensation within a relatively small area that is directly under foveal vision. The results have also confirmed that under the current motion stabilisation regime, the deformation of the periphery does not affect the visual acuity and there is no indication of the deformation velocity of the periphery affecting foveal sensitivity. These findings are expected to have a direct implication on the future design of visual stabilisation methods for robotic assisted MIS. © Springer-Verlag Berlin Heidelberg 2007.

Conference paper

Leong JJ, Nicolaou M, Atallah L, Mylonas GP, Darzi AW, Yang GZet al., 2007, HMM assessment of quality of movement trajectory in laparoscopic surgery., Medical Image Computing and Computer Aided Intervention - MICCAI 2006, Pages: 335-346

Conference paper

Lerotic M, Chung A, Mylonas G, Yang Get al., 2007, pq-space Based Non-Photorealistic Rendering for Augmented Reality, Medical Image Computing and Computer-Assisted Intervention – MICCAI 2007, Publisher: Springer Berlin Heidelberg, Pages: 102-109

Conference paper

Mylonas GP, Darzi A, Yang GZ, 2006, Gaze-contingent control for minimally invasive robotic surgery., Comput Aided Surg, Vol: 11, Pages: 256-266, ISSN: 1092-9088

OBJECTIVE: Recovering tissue depth and deformation during robotically assisted minimally invasive procedures is an important step towards motion compensation, stabilization and co-registration with preoperative data. This work demonstrates that eye gaze derived from binocular eye tracking can be effectively used to recover 3D motion and deformation of the soft tissue. METHODS: A binocular eye-tracking device was integrated into the stereoscopic surgical console. After calibration, the 3D fixation point of the participating subjects could be accurately resolved in real time. A CT-scanned phantom heart model was used to demonstrate the accuracy of gaze-contingent depth extraction and motion stabilization of the soft tissue. The dynamic response of the oculomotor system was assessed with the proposed framework by using autoregressive modeling techniques. In vivo data were also used to perform gaze-contingent decoupling of cardiac and respiratory motion. RESULTS: Depth reconstruction, deformation tracking, and motion stabilization of the soft tissue were possible with binocular eye tracking. The dynamic response of the oculomotor system was able to cope with frequencies likely to occur under most routine minimally invasive surgical operations. CONCLUSION: The proposed framework presents a novel approach towards the tight integration of a human and a surgical robot where interaction in response to sensing is required to be under the control of the operating surgeon.

Journal article

Leong J, Nicolaou M, Atallah L, Mylonas G, Darzi A, Yang Get al., 2006, HMM Assessment of Quality of Movement Trajectory in Laparoscopic Surgery, Medical Image Computing and Computer Aided Intervention - MICCAI 2006

Conference paper

Leong JJ, Nicolaou M, Atallah L, Mylonas GP, Darzi AW, Yang GZet al., 2006, HMM assessment of quality of movement trajectory in laparoscopic surgery., Med Image Comput Comput Assist Interv Int Conf Med Image Comput Comput Assist Interv., Vol: 9, Pages: 752-759

Journal article

Mylonas G, Stoyanov D, Deligianni F, Darzi A, Yang Get al., 2005, Gaze-contingent soft tissue deformation tracking for minimally invasive robotic surgery, Medical Image Computing and Computer Assisted Intervention (MICCAI05), Pages: 843-850

The introduction of surgical robots in Minimally Invasive Surgery (MIS) has allowed enhanced manual dexterity through the use of microprocessor controlled mechanical wrists. Although fully autonomous robots are attractive, both ethical and legal barriers can prohibit their practical use in surgery. The purpose of this paper is to demonstrate that it is possible to use real-time binocular eye tracking for empowering robots with human vision by using knowledge acquired in situ. By utilizing the close relationship between the horizontal disparity and the depth perception varying with the viewing distance, it is possible to use ocular vergence for recovering 3D motion and deformation of the soft tissue during MIS procedures. Both phantom and in vivo experiments were carried out to assess the potential frequency limit of the system and its intrinsic depth recovery accuracy. The potential applications of the technique include motion stabilization and intra-operative planning in the presence of large tissue deformation.

Conference paper

Stoyanov D, Mylonas G, Deligianni F, Darzi A, Yang Get al., 2005, Soft-tissue motion tracking and structure estimation for robotic assisted MIS procedures, Medical Image Computing and Computer Assisted Intervention (MICCAI05), Pages: 139-146

In robotically assisted laparoscopic surgery, soft-tissue motion tracking and structure recovery are important for intraoperative surgical guidance, motion compensation and delivering active constraints. In this paper, we present a novel method for feature based motion tracking of deformable soft-tissue surfaces in totally endoscopic coronary artery bypass graft (TECAB) surgery. We combine two feature detectors to recover distinct regions on the epicardial surface for which the sparse 3D surface geometry may be computed using a pre-calibrated stereo laparoscope. The movement of the 3D points is then tracked in the stereo images with stereo-temporal constrains by using an iterative registration algorithm. The practical value of the technique is demonstrated on both a deformable phantom model with tomographically derived surface geometry and in vivo robotic assisted minimally invasive surgery (MIS) image sequences.

Conference paper

Mylonas GP, Darzi A, Yang GZ, 2004, Gaze contingent depth recovery and motion stabilisation for minimally invasive robotic surgery, Berlin, 2nd international workshop on medical imaging and augmented reality (MIAR 2004), Beijing, Peoples Republic of China, Publisher: Springer-Verlag, Pages: 311-319

Conference paper

Vrielink TJCO, Pang YW, Zhao M, Lee S-L, Darzi A, Mylonas GPet al., Surgical task-space optimisation of the CYCLOPS robotic system

The CYCLOPS is a cable-driven parallel mechanism used for minimally invasiveapplications, with the ability to be customised to different surgical needs;allowing it to be made procedure- and patient-specific. For adequateoptimisation, however, appropriate data on clinical constraints and task-spaceis required. Whereas the former can be provided through preoperative planningand imaging, the latter remains a problem, primarily for highly dexterous MISsystems. The current work focuses on the development of a task-spaceoptimisation method for the CYCLOPS system and the development of a datacollection method in a simulation environment for minimally invasivetask-spaces. The same data collection method can be used for the development ofother minimally invasive platforms. A case-study is used to illustrate thedeveloped method for Endoscopic Submucosal Dissection (ESD). This paper showsthat using this method, the system can be succesfully optimised for thisapplication.

Journal article

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