For medical stereoscopic imaging, the usefulness of the presentation of depth information and the issues of picture quality and fatigue have been discussed. We used a laparoscope that allows switchover between two-dimension (2D) display and three-dimension (3D) display, and compared execution time and accuracy in three kinds of tasks-a pegboard, incision, and suturing-under the 2D and 3D conditions conducted for one hour in total. To avoid the effect of fatigue and order effect to the utmost, an interval of two weeks or more was placed between both experiments. A total of 12 subjects showed higher speed when using the 3D display than the 2D display in all three tasks and, simultaneously, improvement in execution time as a result of order effect. Improvement of task accuracy using 3D display was found in the pegboard task. Large individual variations in execution time were also found. We conclude that the current stereoscopic endoscopes can improve performance of surgical manipulations, but its effect varies from task to task.
This paper describes a method for estimating three dimensional (3D)positions and orientations of vertebrae together with the load working on the vertebral bodies from a sequence of human images taken by a video camera based on a 3D whole body mode and a 3D spine model. In this method, we first obtain the neck and waist postures, the centers of masses of the head, trunk, and arms by fitting the 3D whole body model to an input human image. Then the 3D spine model is deformed so that it satisfies equilibrium of the force working on the vertebrae caused by the springs which approximate intervertebral discs. After determining the spine posture, the load working on the top surfaces of the vertebral bodies is calculated based on the centers of masses and the weights of the body parts. The experimental results based on one real MR image dataset showed that our method estimated the vertebra positions within the positional shifts of 6.2mm and the rotational variation of 3.1 degrees. We also confirmed that our method estimated the spine posture and calculated the force working on the top surface of the lumbar vertebra L, 5' from the real human video images reasonably.
This research aims to produce an intelligent surgical robot, incorporating the following three techniques, A: visual feedback B: force control C: organ-model base control. This research uses a robot model and a liver for the target object to evaluate organ-model base control. For the purpose of organ-model base control, three experiments were conducted to evaluate the physical properties of the liver for robot control. A dynamic viscoelastic test was then carried out to show the dynamic properties of the liver in the form of a differential equation. The nonlinearity of the liver was supported by the creep test. In addition, the liver model was validated using a constant strain rate test.
For fine operations using surgical robot system, surgeons need the information of the contact force loaded on the tip of the surgical instrument. One of major problems in sensing the force is frictional disturbance between the trocar and the instrument. One of authors proposed a new method named overcoat method in which the whole instrument is supported by some force sensors. The overcoat method has two types of construction ways, trocar type and basic type. Trocar hole placed the abdomen in case of the trocar type is smaller than that of the basic type. So, at first, this paper tried to construct a force measuring system with the trocar type. The principle of the overcoat method was discussed concerning to the compensations of gravity and acceleration forces of the instrument in relations to the pose and motion of the instrument. The tried system of the trocar type measured the tip-loaded force in accuracy about 0.1N.
One of authors proposed a new method named overcoat method that is a system for sensing the force loaded on the tip of the surgical instrument. The overcoat method has two types of construction ways, trocar type and basic type. At first, the trocar type was tried, and the abilities and the characteristics of the trocar type were reported. This paper deals with the basic type of the sensor structure with the theoretical way of canceling the acceleration and gravity forces. It pointed out that main error on the force measuring is coursed by inaccurate motion of slave robot, and force measuring error of basic type is smaller than trocar type one.
This paper presents a three-dimensional microfluidic network made of thin mesoporous biodegradable polymer membrane, which realizes rapid transfer of liquid and gas between inside and outside of the microchannel. This is a first prototype of the “artificial blood capillary device” we have proposed to regenerate large tissues and organs in vitro. Here, we prepared porous poly-lactic acid membrane using spincoating following phase separation, and examined the relation of solution composition to pore size and density. We checked the permeability of the prepared membrane for three different dyes which have varying molecular weight. We also investigated the biocompatibility of the membrane by culturing human endothelial cells on the membrane. At last, we successfully fabricated a microfluidic network using membrane micro embossing (MeME) process, and confirmed the size-selective transfer of micro-beads through the microchannel walls.