10:40   Medical Technology
Chair: Jenny Dankelman
15 mins
Gabrielle Tuijthof, Maayke van Sterkenburg, Inger Sierevelt, Jakob van Oldenrijk, Niek van Dijk, Gino Kerkhoffs
Abstract: The demand for high quality care is in contrast to reduced training time for residents in developing arthroscopic skills [1]. Thereto, simulators are introduced to train skills away from the operating room. In our clinic, a physical simulation environment to Practice Arthroscopic Surgical Skills for Perfect Operative Real-life Treatment (PASSPORT) is developed. The concept of PASSPORT consists of maintaining the routinely used arthroscopic equipment, replacing the human knee joint by a phantom, and integrating registration devices to provide direct feedback on performance. The first prototype of the knee phantom allows inspection, treatment of menisci, irrigation and limb stressing. PASSPORT was evaluated for face and construct validity. Construct validity was assessed by measuring the performance of two groups with different levels of arthroscopic experience (twenty surgeons and eight residents). Participants had to perform a navigation task on PASSPORT five times. Task times were registered. Face validity was assessed by completion of a short questionnaire on the participants’ impressions and comments for improvements. For the navigation task, construct validity was demonstrated as the surgeons were more efficient than the residents in task completion for each repetition (Mann Whitney U test, p<0.05). The prototype of the knee phantom sufficiently imitated limb outer appearance, portal resistance, arthroscopic view and joint space. Improvements are required for the stressing device and the material of cruciate ligaments. Our physical simulation environment (PASSPORT) demonstrates its potential to evolve as a training modality. A strong feature is the presence of inherently natural feedback [2]. The possibilities of the PASSPORT are in agreement with the important criteria as determined by a survey amongst orthopedic surgeons [3]. In the future, automated performance feedback is aimed for.
15 mins
Herke Jan Noordmans, Ellen Kuijer, Ilva de Groot, Rowland de Roode, Joris Jaspers, Ruud Verdaasdonk
Abstract: There are several applications where lasers are used to treat skin disorders. Examples are a KTP laser to treat vascular abnormalities like coupe rose and portal wine stains, a Q-switched ND:YAG laser to treat pigment abnormalities and a diode laser to remove hair follicles. Dose settings are often set heuristically based on clinical experience and are adjusted over time depending on the healing response. The maximal dose is usually limited by the pain tolerance and scarring threshold. The instant effect of laser treatment is usually well visible, however, when the patient comes back after several weeks, the final treatment result is less clear. Medical photography is a logical choice to track treatments, but reproducible photography is hard to achieve and can be improved using contrast enhancement and image registration techniques. To investigate the response and healing after skin treatment with laser, a multi-spectral dermatoscope system was applied for skin imaging with a resolution up 10 µm of a 10x10 mm skin area. A spectral scan of 71 images between 435 to 720 nm (stepsize 4 nm) was acquired before and after laser treatment. Motion errors within one spectral scan and camera position errors between two scans were corrected using especially developed registration software. The effect of a KTP laser was studied following five patients during their treatments over a year. Structural changes in the skin after laser induced hair removal was investigated in 10 volunteers undergoing three consecutive laser treatments with a Lightsheer diode laser, 6 weeks apart. In a subsequent study, the skin of three volunteers was imaged at short intervals during two weeks after receiving one laser treatment. Due to changes and disappearance of landmarks, it proved difficult to locate the area under investigation between time intervals. Practical solutions were developed like masks and ink markings. Each pixel of the captured high resolution images contained the full spectral information. The wavelengths of interest were identified to evaluate the changes in e.g. blood perfusion, vasculature and pigments. After exact registration of the images, acute and later changes in the surrounding tissue could be appreciated. The treatment result and healing response could be followed accurately over time with a high resolution. The multi-spectral dermatoscope system provides a perfect tool to study the efficacy and side effects of skin laser treatments and can be used to optimize the treatment plan.
15 mins
Arjo Loeve, Paul Breedveld, Jenny Dankelman
Abstract: Introduction: Flexible endoscopes are widely used to reach sites in the human body that can not readily be reached with rigid endoscopes. However, due to their flexibility, flexible endoscope shafts tend to bend or buckle at crucial moments during interventions. Therefore, new concepts for shaft-guides are being developed and tested. The main function of a shaft-guide is to guide or stabilize the flexible endoscope shaft. Shaft-guides must be compliant during insertion into the body and rigidified when needed to guide or stabilize the flexible endoscope shaft. We developed a new concept (called “Vacu-SL”) that uses vacuum packing of small particles in a foil tube to reversibly change the rigidity of a shaft-guide. From knowledge of soil mechanics it is expected that the type of particles used affect the stiffness of the vacuum packed volume of particles in our design. The goal of this research was to investigate the influence of shape, size and elasticity of the particles on the bending stiffness of a rigidified Vacu-SL shaft-guide in order to help choosing the right particles for the design. Since early test models (filled with glass spheres) were too compliant, particles providing maximum bending stiffness were sought. Materials & Method: Vacu-SL shaft-guide test models were made with a diameter of 17.8 mm and a length of 200 mm. Each test model was filled with a different type of particles. When measuring the effect of one of three properties of interest (shape, size or elasticity) the other two properties were kept constant through selection of the particles. Glass, steel, aluminium oxide and acrylic glass, granulate and spheres, of sizes ranging from 0.158 mm to 1.7 mm, were used in the tests. The test models were prepared according to a preset routine and put in a 10 cm radius bend. The distal end of the bend was attached to a tensile tester. The variable of interest was the force needed to cause a tip deflection of 10 mm. Measurements were repeated five times. Results: Using very irregularly shaped instead of spherical particles increased the bending stiffness of rigidified test models with up to 50%. For acrylic glass, smaller particles gave higher bending stiffness. However, for steel and glass particles there seemed to be an optimal particle size somewhere between the sizes that were tested. There also seemed to be an optimum for granulate particle elasticity. Although steel is stiffer than glass and less stiff than aluminium oxide, using steel granulate particles resulted in a higher bending stiffness than when using glass or aluminium oxide granulate. The maximum load that could be resisted by any of the Vacu-SL shaft-guide test models at 10 mm deflection was 1.5 N, with steel granulate. Conclusion: Particle size, shape and elasticity clearly affect the bending stiffness of a rigidified Vacu-SL shaft-guide. Steel granulate currently provides the highest bending stiffness. Whether this stiffness is sufficient to obtain a proper functioning shaft-guide is the next thing to be investigated. The exact influence of the tested variables and the mechanisms behind it should be further investigated to be able to better predict the influence of using a certain particle type.
15 mins
Christiaan van Swol, Thomas Lango, Maurits de Brauw, Turil Hernes, Geir-Arne Tangen, Ronald Marvik, Anke Smits
Abstract: In laparoscopic surgery the surgeon has to rely on endoscopic camera visualization without haptic feedback. This limits the usefulness of laparoscopy. To improve laparoscopic surgery, we are developing and evaluating a navigation system based on advanced tracking and imaging capabilities. The research platform is capable of importing preoperative images (MRI, CT), as well as real time and freehand three-dimensional (3D) ultrasound images. The navigation system provides the surgeon with an overview of anatomy beyond the surface of organs seen with video-laparoscope. The user can control the visualizations interactively with the tracked surgical instruments. We have attached a tracking device on such instruments as video laparoscopes, special made laparoscopic pointers, laparoscopic graspers, and laparoscopic ultrasound probes. This allows the surgeon to e.g. set the view direction of the navigation display (pre- and intraoperative images) with the video-laparoscope and at the same time see the position and orientation of the other tracked instruments. Furthermore, the tracked grasper can be used to pinpoint structures and also to determine the resection border. We are evaluating the usefulness of the navigation system in a clinical multicenter study using preoperative images in various laparoscopic procedures. So far, we have used the system in laparoscopic adrenalectomies (20), laparoscopic colon cancers (20), and nephrectomies (5). Fiducials were attached to the patients prior to MR/CT imaging with the patient in the same position as the surgery would be performed to minimize anatomic shifts due to gravity. In addition, we have implemented the possibility to shift preoperative images intraoperatively according to such shifts. We believe that navigation during laparoscopic surgery will become an important tool in laparoscopic surgery. In particular, our research and development of the navigation platform has shown positive effects when vessels and anatomic relations might be difficult to identify using video laparoscope view only.
15 mins
Dimitra Dodou, Paul Breedveld, Jenny Dankelman
Abstract: PURPOSE During open abdominal procedures, the surgeon can manipulate the tissue with his hands and gets direct feedback about the applied forces. With the advent of MIS, long rigid instruments such as graspers and retractors have been introduced between the surgeon’s hands and the tissue, and the information about the applied forces has been lost, increasing the number of errors related to MIS graspers. There is considerable research to restore the force feedback of the instrument and prevent the exertion of inadequate grasping forces. We suggest a new concept of grasping, in which force feedback is not required anymore. The idea is to replace the two jaws of a grasper with a sole adhesive flat surface. METHOD The feasibility of ‘adhesive grasping’ was investigated in vitro. For this reason, the effect of the normal force ¬on the gripping force generated by an instrument to a soft tissue was experimentally tested when the surface of the instrument that comes in contact with the tissue was (i) non-adhesive or (ii) adhesive. RESULTS Experiments showed that the adhesive surface generated 15 times higher grip than the non-adhesive one. Most importantly, while the grip of the non-adhesive surface significantly decreased when decreasing the normal force, the grip of the adhesive one remained unaffected. CONCLUSION The experiments showed that, by making a surface adhesive, gripping can be achieved without the need to apply high normal forces: an adhesive grasper would then require only one flat surface instead of two sharp jaws, eliminating the exertion of pinch forces. In other words, when using an adhesive grasper, the surgeon only needs to establish contact with the tissue. Such an approach may contribute in decreasing erroneous task performance and lead hopefully to safer procedures.