No abstract

We conclude that, in agreement with individual experiments, the current overall overlay accuracy is of the order of 2-3 mm in the x-y plane, which is in line with current conventional SN systems. The method which is most in need of improvement is registration, hence we wish to investigate the application of the proposed photo-consistency method further.

The virtual medical laboratory (VML) was conceived to provide an Internet-accessible resource, offering access for clinicians and scientists to an invaluable data archive at the institute of Laryngology and Otology, London. The Institute is home to the largest collection of temporal bone, laryngeal, skull and sinus sections in Europe. The skull and sinus collections include an extensive section consisting of animal material. These were contributions from zoos around the world. Over the last 50 years, samples have been carefully sectioned and stained by specialized technicians to produce histology slices of most regions of the head and neck. The aim of the project is to create a virtual medical laboratory, which will provide access to archived histological material as well as computerized tomography and magnetic resonance data. Central to this aim is the reconstruction of the internal anatomy of the temporal bone from two-dimensional histology slices, to create three-dimensional views that can be used for anatomical simulation and surgical training in otolaryngology. State-of-the-art three-dimensional reconstruction and rendering technology allows us to develop such a model. Computer-generated simulation could be made available to all hospitals in which otolaryngology is practised, via digital communication networks. We aim to develop core technology in our own specialty that is applicable to other fields of higher education, which have not been exposed to such modern teaching modalities. This has the potential to become an invaluable teaching resource for anatomists, surgeons and other scientists.

Abstract. The 'Computer Assisted ENT Surgery using Augmented Reality' (CAESAR) project aims to improve ENT surgical procedures through augmentation of the real operative scene during surgery: a virtual scene, which shows structures that are normally hidden to the eye of the surgeon, is superimposed onto the real scene. The main distinction of this project as opposed to previous work in the field is to create a hierarchical and stepwise implemented system which allows operations such as calibration, tracking and registration to be assessed on an individual basis. This allows us to compare different alternatives for each operation and eventually apply the best solution without interfering with the performance of other parts of the system. In this paper, we present a framework for the alignment of the objects/subject in the real and virtual operating environment before the onset of surgery, and test its performance on a phantom skull. The operations involved are thus based on a static system and include calibration of the stereo microscope and registration of the virtual patient (as reconstructed from CT data) with the real patient. The final alignment of all objects in the real and virtual operating scene is assessed by cumulating maximum errors of each individual step.

Abstract. This paper investigates the potential use of a prototype micro-optic twin Liquid Crystal Display (LCD) monitor for stereomicroscopy in microsurgery. The new device displays stereoscopic images via a pair of colour Charge-Coupled Device (CCD) video cameras attached on to a surgical stereo microscope. The paper illustrates the 3D microscope-display system set-up and calibration for stereo viewing. A series of experimental techniques was devised to measure the user-response of the new display system in depth perception of a solid object against the traditional eyepieces of a stereo microscope. As a control, free viewing with the un-aided eyes was also measured. The positional data were collected using a passive mechanical arm. The results showed good correspondence between all three visualisation methods. Error analysis of our numerical findings suggests that the depth accuracy of the new device is well within the precision limits of hand movement for surgical operations. Our study also proves that there are small discrepancies within the sample population of operators using the system. A study based on the psychological and psychophysical factors influencing the system is planned.