Ken Masamune

System for robotically assisted prostate biopsy and therapy with intraoperative CT guidance

RATIONALE AND OBJECTIVESnThe purpose of this study was to assess the work-in-progress prototype of an image-guided, robotic system for accurate and consistent placement of transperineal needles into the prostate with intraoperative image guidance inside the gantry of a computed tomographic (CT) scanner.nnnMATERIALS AND METHODSnThe coach-mounted system consists of a seven-degrees-of-freedom, passive mounting arm: a remote-center-of-motion robot; and a motorized, radiolucent needle-insertion device to deliver 17-18-gauge implant and biopsy needles into the prostate with the transperineal route. The robot is registered to the image space with a stereotactic adapter. The surgeon plans and controls the intervention in the CT scanner room with a desktop computer that receives DICOM images from the CT scanner. The complete system fits in a carry-on suitcase, does not need calibration, and does not utilize vendor-specific features of the CT scanner.nnnRESULTSnIn open air, the average accuracy was better than 1 mm at a 5-8-cm depth. In various phantoms, the average orientation error was 1.3 degrees, and the average distance between the needle tip and the target was 2 mm.nnnCONCLUSIONnResults of preliminary experiments indicate that this robotic system may be suitable for transperineal needle placement into the prostate and shows potential in a variety of other percutaneous clinical applications.

Image overlay guidance for needle insertion in CT scanner

We present an image overlay system to aid needle insertion procedures in computed tomography (CT) scanners. The device consists of a display and a semitransparent mirror that is mounted on the gantry. Looking at the patient through the mirror, the CT image appears to be floating inside the patient with correct size and position, thereby providing the physician with two-dimensional (2-D) X-ray vision to guide needle insertions. The physician inserts the needle following the optimal path identified in the CT image rendered on the display and, thus, reflected in the mirror. The system promises to reduce X-ray dose, patient discomfort, and procedure time by significantly reducing faulty insertion attempts. It may also increase needle placement accuracy. We report the design and implementation of the image overlay system followed by the results of phantom and cadaver experiments in several clinical applications.

Scrub nurse robot system-intraoperative motion analysis of a scrub nurse and timed-automata-based model for surgery

The goal of the project described in this paper is to develop a human-adaptive Scrub Nurse Robot (SNR) that can adapt to surgeons with various levels of skill and experience in order to compensate for the present severe shortage of scrub nurses. To determine the specifications of the SNR, we analyzed real intraoperative behavior of a scrub nurse, and then modeled the entire surgical procedure with key participants by a multilevel modeling approach using the extended timed-automata-based formalism of Uppaal. Specifically, first, we videotaped the intraoperative motions of a scrub nurse and a surgeon in a thoracoscopic surgery performed on an infant pig, and analyzed their motions during the skin incision. Second, the motions of the nurses right wrist, elbow, and shoulder were modeled with the timed automata. Third, the entire surgical procedure as well as actions and statuses of key participants was also modeled. Finally, it is shown that the proposed multilevel modeling approach also facilitates the model checking that is considered efficient in the SNR motion analysis and its adaptive motion planning.

Three-dimensional medical imaging display with computer-generated integral photography.

A 3-D display system for medical imaging by computer-generated integral photography (IP) has been developed. Real 3-D images are generated from 3-D medical images and displayed by simple structure. Each point in 3-D space is reconstructed by the convergence of rays from many pixels on the computer display through the lens array. Only the coordinate of the best point is computed for each pixel on the display. The locations of images projected within 40mm from the display were found to be less than 2.0mm in error. Projected images could be observed with motion parallax within 10 degrees from the front of the display.

Three-Dimensional Slice Image Overlay System with Accurate Depth Perception for Surgery

In this paper, we describe a three-dimensional (3-D) display, containing a flat two-dimensional (2-D) display, an actuator and a half-silvered mirror. This system creates a superimposed slice view on the patient and gives accurate depth perception. The clinical significance of this system is that it displays raw image data at an accurate location on the patient’s body. Moreover, it shows previously acquired image information, giving the capacity for accurate direction to the surgeon who is thus able to perform less-invasive therapy. Compared with conventional 3-D displays, such as stereoscopy, this system only requires raw 3-D data that are acquired in advance. Simpler data processing is required, and the system has the potential for rapid development. We describe a novel algorithm, registering positional data between the image and the patient. The accuracy of the system is evaluated and confirmed by an experiment in which an image is superimposed on a test object. The results indicate that the system could be readily applied in clinical situations, considering the resolution of the pre-acquired images.

Image overlay for CT-guided needle insertions

Objective: We present a 2D image overlay device to assist needle placement on computed tomography (CT) scanners. Materials and Methods: The system consists of a flat display and a semitransparent mirror mounted on the gantry. When the physician looks at the patient through the mirror, the CT image appears to be floating inside the body with correct size and position as if the physician had 2D ‘X-ray vision’. The physician draws the optimal path on the CT image. The composite image is rendered on the display and thus reflected in the mirror. The reflected image is used to guide the physician in the procedure. In this article, we describe the design and various embodiments of the 2D image overlay system, followed by the results of phantom and cadaver experiments in multiple clinical applications. Results: Multiple skeletal targets were successfully accessed with one insertion attempt. Generally, successful access was recorded on liver targets when a clear path opened, but the number of attempts and accuracy showed variability because of occasional lack of access. Soft tissue deformation further reduced the accuracy and consistency in comparison to skeletal targets. Conclusion: The system demonstrated strong potential for reducing faulty needle insertion attempts, thereby reducing X-ray dose and patient discomfort.

An Image Overlay System with Enhanced Reality for Percutaneous Therapy Performed Inside CT Scanner

We describe a simple, safe, and inexpensive image overlay system to assist surgical interventions inside a conventional CT scanner. The overlay system is mounted non-invasively on the gantry of the CT scanner and it consists of a seven degrees-of-freedom passive mounting arm, a flat LCD display, and a light brown acrylic plate as a half mirror. In a preoperative calibration process, the display, half-mirror, and imaging plane of the scanner are spatially registered by imaging a triangular calibration object. Following the calibration, the patient is brought into the scanner, an image is acquired and sent to the overlay display via DICOM transfer. Looking at the patient through the half-mirror, the CT image appears to be floating inside the patient in correct size and position. This vision enables the physician to see both the surface and the inside of the patient at the same time, which can be utilized in guiding a surgical intervention. The complete system fits into a carry-on suitcase (except the mounting adapter), it is easy to calibrate, mounts non-invasively on the scanner, without utilizing vendor-specific features of he scanner.

Multi-DOF Forceps Manipulator System for Laparoscopic Surgery

Many problems in laparoscopic surgery are due to the poor degrees of freedom of movement (DOF) in controlling forceps and laparoscopes. The Multi-DOF forceps manipulator we have newly developed has two additional DOF of bending on the tip of forceps, and provides new surgical fields and techniques for surgeons. The most remarkable characteristics of the prototype described in this paper are: 1) the small diameter (∅ 6 mm) and the small radius of curvature of bending; 2) the large force generated on each bending and grasping axis; 3) the confirmation of perfect cleanness and sterilization of this manipulator. The effectiveness of these characteristics was confirmed in actual testing by surgeons. This manipulator can solve problems met with in laparoscopic surgery, and will establish new standards for laparoscopic surgery with higher effectiveness and safety.

A Wide-Angle View Endoscope System Using Wedge Prisms

We describe a novel robotic endoscope system. It can be used to observe a wide area without moving or bending the endoscope. The system consists of a laparoscope with zoom facility and two wedge prisms at the tip. This new concept produces excellent characteristics as follows. Firstly, it can change the field of view even in a small space. Secondly, it is safe because it avoids the possibility of hitting internal organs. Finally, because it does not require a large mechanism for manipulation of the endoscope, it does not obstruct the surgeon’s operation. During evaluation, we confirmed that the range of view and levels of image deformation were acceptable for clinical use.

Needle Insertion in CT Scanner with Image Overlay - Cadaver Studies

An image overlay system is presented to assist needle placement in conventional CT scanners. The device consists of a flat LCD display and a half mirror and is mounted on the gantry. Looking at the patient through the mirror, the CT image appears to be floating inside the patient with correct size and position, thereby providing the physician with two-dimensional “X-ray vision” to guide needle placement procedures. The physician inserts the needle following the optimal path identified in the CT image that is rendered on the LCD and thereby reflected in the mirror. The system promises to increase needle placement accuracy and also to reduce X-ray dose, patient discomfort, and procedure time by eliminating faulty insertion attempts. We report cadaver experiments in several clinical applications with a clinically applicable device.