We developed an autostereoscopic display for distant viewing of 3D computer graphics (CG) images without using special viewing glasses or tracking devices. The images are created by employing referential viewing area-based CG image generation and pixel distribution algorithm for integral photography (IP) and integral videography (IV) imaging. CG image rendering is used to generate IP/IV elemental images. The images can be viewed from each viewpoint within a referential viewing area and the elemental images are reconstructed from rendered CG images by pixel redistribution and compensation method. The elemental images are projected onto a screen that is placed at the same referential viewing distance from the lens array as in the image rendering. Photographic film is used to record the elemental images through each lens. The method enables 3D images with a long visualization depth to be viewed from relatively long distances without any apparent influence from deviated or distorted lenses in the array. We succeeded in creating an actual autostereoscopic images with an image depth of several meters in front of and behind the display that appear to have 3D even when viewed from a distance.

In this paper, a level-set-based geometric regularization method is proposed which has the ability to estimate the local orientation of the evolving front and utilize it as shape induced information for anisotropic propagation. We show that preserving anisotropic fronts can improve elongations of the extracted structures, while minimizing the risk of leakage. To that end, for an evolving front using its shape-offset level-set representation, a novel energy functional is defined. It is shown that constrained optimization of this functional results in an anisotropic expansion flow which is usefull for vessel segmentation. We have validated our method using synthetic data sets, 2-D retinal angiogram images and magnetic resonance angiography volumetric data sets. A comparison has been made with two state-of-the-art vessel segmentation methods. Quantitative results, as well as qualitative comparisons of segmentations, indicate that our regularization method is a promising tool to improve the efficiency of both techniques.

This paper describes a surgical manipulator designed with regard to its safety and sterilization in medical setting of anterior cruciate ligament (ACL) reconstruction. The manipulator system consists of two five-bar linkage mechanisms, an optical tracking device, and a user interface of surgical navigation. We designed and fabricated a prototype manipulator and evaluated the performance of the system by a set of experiments. The accuracy evaluation showed that the average backlash of the 4 link axes was 4.14° and the accuracy of the pitch and yaw angle of the K-wire are 1.55° ± 2.74° and −2.48° ± 2.92°. This system enables intrinsic safety and ease of sterilization due to limitations in the range of movement. Furthermore, the system achieves reliability because of the simplicity of both its mechanism and its user interface. The manipulator has the potential to be used in minimally invasive ACL reconstruction surgery, although further improvements and experiments remain to be carried out.

This paper describes a manipulator for controlling position and posture of fetus in uterus and a surgical procedure for supporting the fetus in intrauterine surgery. The manipulator is equipped with multiple linkages and a balloon to support the fetus softly in the uterus. The linkages with two bending mechanisms are designed for inserting the balloon to an optimal position under the fetus. The balloon is fold before the operation and inflated by saline water after arriving at the required position in the uterus. Accuracy evaluation showed that the standard deviations of the bending angle of the wire-driven mechanism and the linkages-driven mechanism were 1.0 degree and 2.5 degree, respectively. Force experiment showed that the balloon-type stabilizer could generate load-bearing power of 500 gf. Furthermore, the manipulator could be well controlled with guidance of ultrasound images. The manipulator could minimize injure to the fetus since the area contacted with the fetus by the balloon could be well controlled.

three-dimensional (3D) computer graphics (CG) image without using special viewing glasses or tracking devices. The images are created by employing a light field rendering and pixel distribution algorithm for integral photography (IP) / integral videography (IV) imaging. How to enhance the image depth, especial the long visualization depth, is a challenge work. In this study, the images are rendered from a referential viewing area for each viewpoint and the elemental images are reconstructed by pixel redistribution method. The corresponding result images are projected to a screen that is separated from the lens array by a referential viewing distance as the setting of image rendering. A photographic film is used to record the elemental image through each lens with a photograph-taken method. Our photograph-taken based IV display enables precise 3D images with long visualization depth to be displayed at long viewing distances without any influence from deviated or distorted lenses in a lens array. We created an autostereoscopic display that appears to have three-dimensionality even when viewed from a distance, with an image depth of 5.7 m or more in front of the display. To the best of our knowledge, the presented long-distance IV display is technically unique as it is the first report of generating an autostereoscopic image with such a long viewing distance in the field of computer graphics. CR Categories and Subject Descriptors: B.4.2 Input/Output Devices - Image Display

A prototype master-slave system consisting of two MR-compatible manipulators with interchangeable surgical tools was designed, implemented, and evaluated. The manipulators are designed so as to fit into vertical-magnetic-field open-configuration MR imagers. They are also designed so that the surgical tool mounted at the tip of their arm is interchangeable. The MR compatibility of the manipulator including a surgical tool was evaluated by moving it close to a phantom in the field of view of an open-configuration MR imager. No noticeable deformation, but deterioration in the signal-to-noise ratio of approximately 10 percent, was observed in the MR images. Consulted clinicians then evaluated the manipulability of the master-slave system by maneuvering a pair of slave manipulators through an operation input device consisting of a pair of master manipulators. After several minutes of trial and error, they could perform each primitive motion for suturing tasks on training material mimicking human tissue.

Transurethral resection of the prostate (TUR-P) is a common treatment for benign prostatic hyperplasia (BPH). However, the damage to the mucous membrane of the urethra leads to the complications. This paper reports a tubular organ resection manipulator for transurethral resection of the prostate which can minimize damage to the mucous membrane of the urethra using a prostate displacement mechanism and a continuous perfusion-resection mechanism. The manipulator has an arm, a cutter and a drill at the endeffector, and has 4 degrees-of-freedom: bending the arm, translating the cutter, rotating the drill and rotating the endeffector. The arm displaces the prostate, and the cutter is inserted linearly into the prostate and removes enlarged tissue by drilling. Combination of the arm and cutter enables the manipulator to remove sufficient volume of enlarged prostate through small incision on the urethra, thus minimizing the damage to the urethra. After finishing one plane cutting, the manipulator rotates its body and removes another part of the prostate gland. In performance experiments, each mechanism (bending motion, insertion, and body rotation) had high repeatability within 1.0 degree and within 0.1 mm. In phantom study, the manipulator could displace gelatin model accurately with sufficient power, and could reach and remove wide range of sample tissue (589.2 mm/sup 2/ in one procedure). These results showed that the manipulator can displace the prostate and remove sufficient volume of the prostate tissue through a small incision on the urethra.

This paper describes an autostereoscopic image overlay technique that is integrated into a surgical navigation system to superimpose a real three-dimensional (3-D) image onto the patient via a half-silvered mirror. The images are created by employing a modified version of integral videography (IV), which is an animated extension of integral photography. IV records and reproduces 3-D images using a microconvex lens array and flat display; it can display geometrically accurate 3-D autostereoscopic images and reproduce motion parallax without the need for special devices. The use of semitransparent display devices makes it appear that the 3-D image is inside the patient's body. This is the first report of applying an autostereoscopic display with an image overlay system in surgical navigation. Experiments demonstrated that the fast IV rendering technique and patient-image registration method produce an average registration accuracy of 1.13 mm. Experiments using a target in phantom agar showed that the system can guide a needle toward a target with an average error of 2.6 mm. Improvement in the quality of the IV display will make this system practical and its use will increase surgical accuracy and reduce invasiveness.

This paper proposes a new endoscopic hand-held forceps manipulator for endoscopic surgery using two bending mechanisms by multi-slider linkage mechanisms to achieve high mechanical performance and applicability. A bending mechanism consisted of three outer frames, two rotating joints and two sliding linkages for drive and restraint. Two pin-joints could rotate /spl plusmn/45 degrees respectively, enabling rotation of /spl plusmn/90 degrees. The rotation of the joint was available by pulling/pushing the adjacent element by sliding linkage in order. We connected two bending mechanisms, one was for the horizontal plane bending and the other was for the vertical plane bending, enabling 2-DOFs independent motions between -90 degrees and +90 degrees. The 2-DOFs bending mechanism and 1-DOF forceps mechanism were driven by three brushless DC-servomotors. A personal computer-based control unit determined displacement of sliding two linkages and of pulling one wire by the target angle of each DOF mechanism. We examined the actual angle of 2-DOFs bending mechanism, obtaining repeatability of /spl plusmn/0.87 degrees in the horizontal plane bending and /spl plusmn/0.91 degrees in the vertical plane bending. In vivo experiment, this manipulator performed endoscopic surgical tasks under pneumoperitoneum. In conclusion, we were sure of a usefulness of multi-slider linkage mechanism for the new handheld forceps manipulator for clinical application, which showed high repeatability of less 1.0 mm and large workspace with sufficient holding power of 0.55 kgf.

A novel device is described for efficiently harvesting bone marrow in bone marrow transplantation that uses a newly developed passive flexible drilling unit and suction mechanism. The device reduces the invasiveness of bone marrow harvesting by collecting stem cells from the iliac bone with minimal punctures and by reducing the operation time and the contamination by T-cells. The device is inserted into the medullary space from the iliac crest and aspirates the bone marrow while an end mill on the tip of the drilling unit drills through the cancellous bone to create a curved path. In vitro and in vivo pig studies showed that the device can be inserted into the medullary space of the pig iliac bone, 131 /spl times/ 32.1 mm/min, and used to harvest about six times as much bone marrow per puncture as the conventional aspiration method. They also showed that the device can generate higher and longer negative pressure (-76.9 kPa for 5.96 s) than the aspiration method (-41.8 kPa for 4.97 s). The device, when applied in clinical study, will reduce invasiveness by harvesting denser graft from a wider area of the iliac bone compared to the conventional aspiration method, although minimal puncturing is required.