This paper presents a deformable hollow organ model considering the self-collision between the inner surfaces of a
hollow organ for real-time surgical simulation. The hollow organ was modeled by the finite element method with 10400
tetrahedral elements, 2160 nodes, and 1040 inner meshes. In the model, the continuous collision detection is performed
between the inner surfaces to prevent penetrations of them. As a result, it was shown that the model is well-behaved
about 40 fps by a standard PC with Pentium4 3GHz and 2GB RAM.
In recent years, various kinds of endoscope have been developed and widely used to endoscopic biopsy, endoscopic
operation and endoscopy. The size of the inflammatory part is important to determine a method of medical treatment.
However, it is not easy to measure absolute size of inflammatory part such as ulcer, cancer and polyp from the
endoscopic image. Therefore, it is required measuring the size of those part in endoscopy. In this paper, we propose a
new method to measure the absolute length in a straight line between arbitrary two points based on the photogrammetry
using endoscope with magnetic tracking sensor which gives camera position and angle. In this method, the stereo-corresponding
points between two endoscopic images are determined by the endoscopist without any apparatus of
projection and calculation to find the stereo correspondences, then the absolute length can be calculated on the basis of
the photogrammetry. The evaluation experiment using a checkerboard showed that the errors of the measurements are
less than 2% of the target length when the baseline is sufficiently-long.
We propose a new projector-based augmented reality (PBAR) system which can project the image of forceps and a
surgical target simultaneously for support of laparoscopic surgery. A compensation method of an error arisen from
motion of a body is also proposed to improve the quality of the projection images. It is shown that the system is
significant for the forceps insertion by the experiments using the dry-box.
We propose a fast stereo matching algorithm for 3D reconstruction of internal organs using a stereoscopic laparoscope.
Stoyanov et al. have proposed a technique for recovering the 3D depth of internal organs from images taken by a stereoscopic laparoscope. In their technique, the dense stereo correspondence is solved by registration of the entire image. However, the computational cost is very high because registration of the entire image requires multidimensional optimization. In this paper, we propose a new algorithm based on a local area registration method that requires only low-dimensional optimization for reduction of computational cost. We evaluated the computational cost of the proposed algorithm using a stereoscopic laparoscope. We also evaluated the accuracy of the proposed algorithm using three types of images of abdominal models taken by a 3D laser scanner. In the matching step, the size of the template used to calculate the correlation coefficient, on which the computational cost is strongly dependent, was reduced by a factor of 16 as compared with the conventional algorithm. On the other hand, the average depth errors were 4.68 mm, 7.18 mm, and 7.44 mm respectively, and accuracy was approximately as same as the conventional algorithm.
Laparoscopic surgery without ventrotomy has been widely used in recent years for quick recovery and out of pain
of patients. However, surgeons are required to accumulate various experiences for this surgery since the difficulty
in perceiving the positions of tissues by the limited field of view (FOV) of laparoscopes and the operational
difficulties of forceps. In this paper, we propose a new laparoscopic surgery supporting system using projected
images. The image of the FOV of a laparoscope is projected directly onto the abdominal surface of a patient.
The shape distortion of the projected images produced by the unevenness of the abdominal surface is corrected
by grating projection. The distortion due to the viewing angle of the surgeon is also corrected by using an
electromagnetic tracking sensor. It is shown that the proposed system is significant to laparoscopic surgery,
particularly for forceps insertion, by experiments using a model of the abdomen made with a dry box.