The use of minimally invasive procedures for breast tumor diagnosis and treatment, such as needle biopsy and radiofrequency ablation (RFA), is steadily increasing. Accurate needle insertion requires solving the problems of tissue deformation and target displacement. In this study, we developed a robotic needle insertion method to improve the precision of diagnostic biopsy and RFA treatment. The mechanical probe was designed to reduce tissue displacement by pressing the breast tissue before needle insertion: a technique that is known as preloading. We focused on the needle insertion phase and evaluated the insertion accuracy achieved. Using a numerical simulation model and an actual hog breast, we compared tissue preloaded needle insertion with normal needle insertion. The data obtained with both test systems showed that targeting errors were greatly reduced using preloading-based needle insertion, as compared with normal needle insertion. The procedure is expected to offer a safe and effective alternative to the traditional methods of needle insertion for breast tissue biopsy or RFA. Our study also revealed the relationship between insertion accuracy and preloading probe force.

We describe a palpation-based needle insertion method for diagnostic biopsy and radiofrequency ablation treatment of a breast tumor. The mechanical palpation probe locates cancerous tissue from ultrasound imaging information and reduces tissue displacement during needle insertion by pressing the breast tissue. We examined the insertion accuracy of this method and compared palpation-based needle insertion with normal needle insertion both in vitro and in vivo. Palpation-based needle insertion had a smaller error, suggesting that this procedure is a safe, effective alternative to traditional methods of breast needle insertion.

We describe here a palpation-based needle insertion method for diagnostic biopsy and treatment of breast cancer. The mechanical palpation probe locates cancerous tissue from force information and reduces tissue displacement during needle insertion. We compared palpation-based needle insertion to normal needle insertion by numerical simulation of a breast tissue model and by experiments in vitro. The data showed palpation-based needle insertion had a smaller error in both tests. Our findings suggest the procedure is a safe, effective alternative to traditional methods of breast tissue biopsy.

This paper describes a ultrasound (3-D US) system that aims to achieve augmented reality (AR) visualization during laparoscopic surgery, especially for the liver. To acquire 3-D US data of the liver, the tip of a laparoscopic ultrasound probe is tracked inside the abdominal cavity using a magnetic tracker. The accuracy of magnetic trackers, however, is greatly affected by magnetic field distortion that results from the close proximity of metal objects and electronic equipment, which is usually unavoidable in the operating room. In this paper, we describe a calibration method for intraoperative magnetic distortion that can be applied to laparoscopic 3-D US data acquisition; we evaluate the accuracy and feasibility of the method by in vitro and in vivo experiments. Although calibration data can be acquired freehand using a magneto-optic hybrid tracker, there are two problems associated with this method--error caused by the time delay between measurements of the optical and magnetic trackers, and instability of the calibration accuracy that results from the uniformity and density of calibration data. A temporal calibration procedure is developed to estimate the time delay, which is then integrated into the calibration, and a distortion model is formulated by zeroth-degree to fourth-degree polynomial fitting to the calibration data. In the in vivo experiment using a pig, the positional error caused by magnetic distortion was reduced from 44.1 to 2.9 mm. The standard deviation of corrected target positions was less than 1.0 mm. Freehand acquisition of calibration data was performed smoothly using a magneto-optic hybrid sampling tool through a trocar under guidance by realtime 3-D monitoring of the tool trajectory; data acquisition time was less than 2 min. The present study suggests that our proposed method could correct for magnetic field distortion inside the patient's abdomen during a laparoscopic procedure within a clinically permissible period of time, as well as enabling an accurate 3-D US reconstruction to be obtained that can be superimposed onto live endoscopic images.

Remote surgery is one of the most desired applications in the context of recent advanced medical technologies. For a future expansion of remote surgery, it is important to use conventional network infrastructures such as Internet. However, using such conventional network infrastructures, we are confronting time-delay problems of data transmission. In this paper, a remote surgery experiment between Japan and Thailand using a research and development Internet is presented. In the experiment, the image and audio information was transmitted by a newly developed low latency CODEC system to shorten the time-delay. By introducing the low latency CODEC system, the time-delay was shortened compared with the past remote surgery experiments despite the longer distance. We also conducted several network measurements such as a comparison between TCP/IP and UDP/IP about the control signal transmission.

Several robotic surgical systems have been developed for MIS (minimally invasive surgery) including commercialized products such as da Vinci and ZEUS. We have developed a minimally invasive surgical system, which have carried out remote surgery experiments for five times at the writing time. In this paper, a remote surgery experiment, which was conducted between Japan and Korea by using the developed minimally invasive surgical system is described. Research & Development (R & D) Internet testbet, APII (Asia-Pacific Information Infrastructure), which consists of an optical submarine cable network KJCN (Korea-Japan Cable Network), was used. In the experiment, a laparoscopic cholecystectomy was successfully carried out on a pig. The network time-delays of control signal and images were 6.5 msec and 435.5 msec respectively. A comparison of remote surgery experiments using ISDN and the Internet was studied