Technology and Health Care - Volume 12, issue 3

Authors: Lavelle, S.M. | Walton, P.W. | Iomhair, Maura Mhic

Article Type: Research Article

Abstract: An implant can act as a physical carcinogen. Chemicals applied to its surface can augment that. To explore if cocarcinogenesis would affect the incidence of tumour on implants, we tested several physical (asbestos, beta irradiation) and chemical (acridine orange, phorbol methyl ester, cigarette smoke tar, extract of Agaricus bisporus mushroom) carcinogens on 25 mm diameter nitrocellulose filters implanted in groups of BALB/c mice in 9 experiments. Saline was applied in 287 concurrent controls. Irradiation by 540 kBq I-125 fibrinogen on foreign bodies of surface area 20sq cm induced tumour in 6/6 pilot animals (expected 2/6) and in 25/36 animals (controls …13/29; p<0.04). The mean dose (beta and gamma) to cells within 20 μm of the filter surface was estimated to be 782 mGy. Exposures to 270kBq or less were not significantly cocarcinogenic with single implants. Radiation from the paired implants was detectible up to 80 weeks. Asbestos, however, 2.3 or 4.6 mgm on implants did not in 3 trials increase sarcoma yield significantly, but did induce mesothelial-type growths in the peritoneum. Asbestos (2.3 mg) injected without an implant provoked no tumour at the site. The chemical carcinogen acridine orange gave ambiguous results, and the others reduced tumour incidence insignificantly. The irradiation history may be germane in the human cases that arise. Show more

Keywords: foreign body, sarcoma, co-carcinogens, radiation, asbestos, iodine125, cigarette tar, phorbol, physical carcinogenesis

DOI: 10.3233/THC-2004-12301

Citation: Technology and Health Care, vol. 12, no. 3, pp. 217-223, 2004

Authors: Ohta, Makoto | Handa, Akira | Iwata, Hiroo | Rüfenacht, Daniel A. | Tsutsumi, Sadami

Article Type: Research Article

Abstract: Purpose: To develop a vessel model with poly-vinyl alcohol hydrogel (PVA-H) with low surface friction for in vitro simulations of vascular pathologies. Materials and methods: Simulations of variable vascular pathologies were based on human vessel casts reproduced in wax. Constructions of vascular models were then obtained by lost wax techniques. As materials, liquid silicon or PVA in organic solvents were used. After solidification, the wax was drained by heating. Comparison of PVA-H with silicone models included evaluation of surface characteristics (friction coefficient), of visibility (transparence and compatibility with medical imaging techniques), and of stiffness (pulsatility of vascular lumen). …Both model types were integrated in a circulation circuit allowing for flow simulations and testing with endovascular medical devices. Results and conclusion: Both model types were transparent and compatible with current medical imaging methods. PVA-H models exhibited much lower friction characteristics. PVA-H stiffness was closer to soft tissue when compared to silicone, allowing for pulsations during flow simulations. Show more

Keywords: aneurysm, friction, poly-vinyl alcohol hydrogel (PVA-H), endovascular treatment, phantom

DOI: 10.3233/THC-2004-12302

Citation: Technology and Health Care, vol. 12, no. 3, pp. 225-233, 2004

Authors: Heidelberger, Bruno | Teschner, Matthias | Frauenfelder, Thomas | Gross, Markus

Article Type: Research Article

Abstract: Efficient collision handling of dynamically deforming anatomical models is a very challenging problem in real-time surgery simulation. In this paper, we present a new, efficient approach that detects collisions and self-collisions of deformable models. Our algorithm is integrated in a simulation framework for multiple interacting objects. This framework consists of three components. The first one computes the dynamic behavior of deformable structures using an efficient and robust approach with distance- and volume-preserving constraints. The second component detects collisions and self-collisions of deformable models. A novel image-space technique is employed that detects volumetric intersections. This allows to compute the penetration depth …which is used to resolve collisions in the third component of our framework. Our system handles volumetric deformable models of up to several thousand surface triangles and tetrahedra in real-time and can be used in surgical training systems. Show more

DOI: 10.3233/THC-2004-12303

Citation: Technology and Health Care, vol. 12, no. 3, pp. 235-243, 2004

Authors: Grätzel, C. | Fong, T. | Grange, S. | Baur, C.

Article Type: Research Article

Abstract: We have developed a system that uses computer vision to replace standard computer mouse functions with hand gestures. The system is designed to enable non-contact human-computer interaction (HCI), so that surgeons will be able to make more effective use of computers during surgery. In this paper, we begin by discussing the need for non-contact computer interfaces in the operating room. We then describe the design of our non-contact mouse system, focusing on the techniques used for hand detection, tracking, and gesture recognition. Finally, we present preliminary results from testing and planned future work.

Keywords: vision-based interface, hand gesture recognition, surgeon-computer interaction

DOI: 10.3233/THC-2004-12304

Citation: Technology and Health Care, vol. 12, no. 3, pp. 245-257, 2004

Authors: Weiss, St. | Bajka, M. | Nava, A. | Mazza, E. | Niederer, P.

Article Type: Research Article

Abstract: The behaviour of the human uterus under an internal (intracavital) pressure of 150 mm Hg (20 kPa) was modelled. The application of such an intracavital or intrauterine pressure corresponds to the procedure which is performed at the beginning of hysteroscopy (hydrometra). Homogenous, isotropic material laws were implemented in a three dimensional, finite element model. The volume of the distended uterine cavity was calculated with different parameters obtained from in vivo aspiration experiments on human uteri as well as from ex vivo tensile tests on rabbit uteri for comparison purposes. The calculated results were in general agreement with in vivo measurements …of hydrometra performed at the University Hospital of Zurich. Show more

DOI: 10.3233/THC-2004-12305

Citation: Technology and Health Care, vol. 12, no. 3, pp. 259-267, 2004

Authors: Nava, Alessandro | Mazza, Edoardo | Kleinermann, Frederic | Avis, Nick J. | McClure, John | Bajka, Michael

Article Type: Research Article

Abstract: A proper mechanical characterization of soft biological tissues of the human body has a strong impact on several medical applications such as surgical planning, virtual reality simulators, trauma research, and for diagnostic purposes. Adequate experimental data are needed to describe quantitatively the mechanical behaviour of those organs. We present a technique for the acquisition of such data from soft tissues and its post processing, based on a continuum mechanics approach, to determine some parameters of the tissue's mechanical properties. A small tube is applied to the target organ and a weak vacuum is generated inside the tube according to a …predefined pressure history. A video camera grabs images of the deformation profile of the aspirated tissue, and a pressure sensor measures the correspondent vacuum level. The images are processed and used to inform the fitting of uniaxial and continuum mechanics models. Whilst the aspiration test device is suitable for in vivo applications, under sterile conditions during open surgery, we hereby present first results obtained by testing cadaveric tissues. Show more

DOI: 10.3233/THC-2004-12306

Citation: Technology and Health Care, vol. 12, no. 3, pp. 269-280, 2004

Authors: Hieu, L.C. | Vander Sloten, J. | Bohez, E. | Phien, H.N. | Vatcharaporn, E. | An, P.V. | To, N.C. | Binh, P.H.

Article Type: Research Article

Abstract: Skull defects are treated by cranioplasty techniques, which are required to protect underlying brain, correct major aesthetic deformities, or both. This research is a part of our research project in ASEAN countries to investigate (i) the methods for design and manufacturing of cranioplasty implants, and (ii) the feasible technical solutions of minimizing the implant cost based on available production and biomaterial technologies in the region. In this paper, solutions for design and manufacturing of standardized implant templates (SDT) are presented. SDT are made based on the reverse engineering and rapid tooling techniques. With the use of SDT, surgeons have flexible …options in preparing the implant both pre and intra operatively, and the operation time is minimized. In addition, the skills required to prepare an implant from SDT are not highly required. The cost for cranioplasty treatments by using SDT is acceptable for ASEAN region. Show more

Keywords: cranioplasty, implant

DOI: 10.3233/THC-2004-12307

Citation: Technology and Health Care, vol. 12, no. 3, pp. 281-292, 2004