We have ever proposed the method of active control of microbubbles under ultrasound exposure for the future drug delivery system. Recently we adopted bubble liposomes (BLs) because they can contain various kinds of drug. However it has problems in BLs, which are easy to destruct under ultrasound exposure. First we have found the appropriate parameters of ultrasound to suppress the destruction indices of BLs in a flow circuit including artificial blood vessel. Evaluation method of BLs is concentration using brightness on echograms. We succeeded to induce BLs with maximum induction index of 79 %, where destruction index of 30 % was acceptable.

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The purpose of this study is to develop computer simulation program which realize the preoperative anatomical fitting test of a ventricular assist device (VAD) for each patient. Using the CT images, the three-dimensional (3D) surface of the thoracic cavity was constructed on the computer. The surfaces of the VAD in STL format was superimposed on that of thorax to examine anatomical compatibility of the VAD. As a result, display time of 51396.8±383.7ms and RAM usage of 7.852±0.151 GB (n=5) are required to construct the 3D image for the CT images of 439 slices (Fig.1). It was suggested that the performance of the newly developed program is enough to test anatomical fitting of the VAD.

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The left ventricular assist device(LVAD) has not only a role as the circulatory support but also as left ventricular unloading.Although high assist rate is effective for ventricular unloading,it may cause aortic flow stagnation,which may cause thrombosis or fusion of the aortic valve.Therefore,it is important to adjust a pump output corresponding to a condition of aortic valve opening.In this study,a method for detecting whether aortic valve is open has been proposed and evaluated.Support Vector Machine(SVM) of which feature variables were a rotational speed and current consumption was used for state classification.In addition,the empirical verification algorithm was applied to SVM output in order to improve sensitivity and specificity.The training and evaluation data were obtained from animal experiments using adult goats.The SVM gave a good performance when second derivative of the variables were used as features.The result indicated that the proposed algorithm have practical performance for aortic valve state detection.The information of an aortic valve state may contribute to development for automatic controller for LVAD.In future study,it is necessarily to investigate an individual difference of the parameters.

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It is reported that a synchronized control of rotary left ventricular assist devices has some advantages in comparison with constant rotational speed control. The most common way to synchronize to heart beat is to use ECG signal because R-wave represents the beginning of systole and is easily detected. However, it is difficult to detect the onset of diastole. The aim of this study is to develop the algorithm to synchronize to heart cycle without external sensors such as ECG.In proposed method, a heartbeat was regarded as disturbance to pump rotational speed. Thus the disturbance was estimated as the difference between measured and estimated rotational speed. An ARX model which input was the reference of pump speed and current consumption was adopted to estimate the instantaneous rotational speed. The proposed method was tested in both a mock circulatory system and animal experiments. The results indicated that the system can output the heart cycle signal and detect not only the onset of systole but that of diastole. Furthermore, co-pulse and counter-pulse mode control can be demonstrated by using the detected timing. However there was detection delay at start of systole.

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In recently, PCPS and/or ECMO were got an opportunity to use in the field of critical care. But, these devices were so large to carry by hands and difficult to maneuver inexperienced worker. To solve the problems, we are developing a portable PCPS, called the Emergency Life Support System(ELSS). And the sequential flow pump (SFP) was designed for the build-in blood pump of the ELSS.
In this study, the optimal number of vanes for impeller in SFP was examined in two conditions using the computational fluid dynamics (CFD) analysis.First, the number of vanes was changed 6, 8 and 10 with constant vane pass volume. Second, the number of vanes was changed from 6 to 30 with constant priming volume in the impellers.
As results from CFD, in the first condition, the head pressure increased from 372mmHg to 408mmHg in proportion to the number of vanes. In the second condition, the peek head pressure was achieved in 12 vanes.

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Heart-lung equipments are useful to save life of acute heart failure and respiratory distress patients. To realize a compact heart-lung equipment, the pump that generates high pressure with low flow is appropriate. To meet the purpose, we have been developing a novel centrifugal pump named sequential flow pump (SFP).The SFP has a structure that centrifugal force is given sequentially two times to the fluid with a single impeller. Since the SFP adopts single pivot or hydrodynamic bearing, axial balance of the impeller is essential. In this study, axial balance of the impeller was examined using computational fluid dynamics (CFD) analysis and actual models. In the experimental model, the impeller could be balanced up to 3200 rpm of rotational speed. However, stability was not so good.To improve the stability, a new model, in which basic simple straight-pass impeller could be balanced up to 1900 rpm of rotational speed, was developed. Various impellers were investigated in this pump. The results showed that the impeller having special shape in periphery would be excellent.

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Sensor less estimation of pressure and flow was important subject for developing total artificial heart. However, estimated value is affected by viscosity change that occurs in living body usually. In this study, we proposed a novel method for viscosity estimation utilizing the table estimation method. Within short time like one plus, change in blood viscosity and peripheral resistance is considered to be little between systolic or diastolic phases. In the same viscosity, different resistance curves never cross. These characteristics suggest that viscosity could be estimated by motor information of systolic and diastolic phases. The helical flow pump was connected to the mock circulation and tables were created by using known viscosity fluids. Standard data were measured with continuous and pulsatile modes. Estimation accuracy was examined with two continuous-flow conditions regarded to systolic and diastolic phases. There fould a tendency that the more difference two conditions were, the more accurate estimation could be possible. Almost the same results were obtained on pulsatile mode. Possibility of the proposed estimation method was demonstrated.

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In baroreflex mechanism, since a brain can be thought to vary cardiac output harmonizing with peripheral vascular resistance by sensing pressure variation at about 0.1Hz(this oscillation is called Mayer waves), it can be said to filter blood pressure fluctuation.On the other hand, 1/R, and ΔP control methods was developed for realizing physiological circulation of a total artificial heart(TAH). One of problems of these methods is matching cardiac output rhythm of TAH to the Mayer waves in a natural heart for steadily of blood pressure.Aortic pressure is one of input factors for these control methods, a low-pass filter is applied to for cutting noise. Therefore, it is expected to provide Mayer waves similar physiological fluctuations in cardiac output of TAH, by obtaining a filter with the same function as a brain, and using it as a filter for the input factors.As a result of analysis for hemodynamics of a TAH goat these control methods had being applied to and of a normal goat, and analysis for this of same TAH goat with different time constant of the low-pass filter, peak frequency differed between these goats, and by the time constant. The relation of the time constant and the frequency has being considered.

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In the development of total artificial heart (TAH), we must design left and right pumps separately to achieve a proper flow balance. In this study, we designed a motor of pump to maintain right heat circulation and prototyped. The Motor was designed by using Assumptive Magnetic Flux Path Method. We made equivalent circuit by this method, and evaluated synthetic reluctance, magnetic flux of gap for the purpose of inhibiting magnetic saturation. We adopted structure of DC brushless, four poles and 12 slots. We assumed the pump efficiency was 50%.We set maximum amount of cardiac output was 10L/min, maximum pressure was 20mmHg when rotation number was 3000rpm.In measurement, we examined the effect of gap difference, we changed the gap was 1.0 mm and 1.5 mm respectively. Result of measurement, torque and speed constants was 55 mNm/A and 180 rpm/V, 51 mNm/A and 198 rpm/V when the gap difference was 1.0 mm and 1.5 mm respectively. We confirmed the characteristics of the motor tend to high torque when the gap is narrow. On the other hand, it tends to high revolution when the gap is wide.

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Due to large power consumption, the artificial heart is currently supplied power from outside of the body by the cable, which penetrates the skin and causes bacterial infection. Transcutaneous energy transmission system (TETS) has been conducted to solve this problem. Recently, there have been several big challenges in litz wire coil for TETS; a size limit, decline in coupling efficiency by positional deviation between coils, and etc. In this study, we focused on preventing the deviation. We made coils of flexible board to embed it into side chest, a very small region hardly affected by human's motion. The coil was double sided, its thickness 85 um enabled to decrease coil pressure to the body as well as increase choices of implantable site. The coil had 12 wire turns, its diameter was 98.4mm, and its inductance and resistance was 10 uH and 782 mΩ. In addition, formerly we intended to reduce the resistance with coils parallel connected, yet that was interfered by eddy current result from the line width of coil. We insulted 29 slits into each line thereby. As a result, we achieved 27.5 W transmission with three coils parallel connection on condition that the resistance was 318 mΩ.

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Development of internal rechargeable battery for totally implantable artificial organs is major problem for transcutaneous energy transmission systems (TETS). Also their charging systems have to be considered. Lithium ion batteries were charged in the constant current (CC), constant voltage (CV) method. A switching mode converter is used for this charge control. However devices are suffered from high frequency and ripple current and voltage. Their risks of failure are relatively high, also size and temperature rise are great concerns. In this study, we examined a new internal rechargeable battery charge system. In which the battery is directly connected to the output of the internal rectifying circuit of TETS, and the charging current is controlled by the external circuit.Our TETS has a series resonant property therefore, by changing driving frequency, the output can be controlled. The input current is sensed and controlled to be a constant current by changing frequency. When the frequency reaches the lower limit, the maximum output voltage is induced. Therefore the rechargeable battery is connected via an overvoltage protective circuit.

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Many artificial hearts (AH) have been controlled according to an amount of blood flow in the end diastolic volume. Natural hearts, on the other hand, modify outputs under affection of the nervous systems. The nerves connecting the brain and the heart are promising to contain rich information for the AH control. In this study, we measured vagal nerve signals from a goat with an in-vivo ventricular assist device, applying a pair of hook electrodes in the left vagal nerve. Another pair of hook electrodes was placed on the skin to acquire electrical noises. A Wiener filter was designed to subtract the noises on the skin from the vagal nerve signals. As we estimated a mutual correlation between amplitudes of the processed neural signals and aortal pressures, a correlation peak was found at 200 ms lag of time, suggesting the processed neural signals contain a component to represent aortal pressures. It is reasonable to assume the time delay as a time for the brain to receive aortal pressure information and to generate a control command for the heart. We therefore suppose the component originated from the efferent nerve fibers which would provide an information source for AH control.

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We have developed a transcutaneous communication system using intrabody communication, and we proposed a titanium mesh electrode to obtain mechanically and electrically stable contact with tissue by inducing surrounding tissue. In this study, we studied histocompatibility of the titanium mesh with the inner wall of the thoracic cavity using a goat. A transmission current of 6 mA with a frequency of 4 MHz is within maximum allowable current applying a human body according to the ICNIRP guideline. However, the data transmission current had an effect on the tissue inside the titanium mesh, and more numbers of inflammatory cells were induced into the titanium mesh. The titanium mesh electrode on the internal communication unit was filled with more numbers of inflammatory cells rather than the titanium mesh electrode implanted alone. Stress inside the titanium mesh due to movement of the communication unit would evoke immune reaction, and it induced inflammatory cells into the titanium mesh. While physical stimuli such as stress and current would evoke week inflammatory immune response, the titanium mesh is suitable material for an electrode that can be implanted inside the body.

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The authors have been developing a pulmonary mechanical simulator in order to establish a design parameters of a novel artificial cardiovascular devices. In pulmonary circulation, interactive pressure-flow changes are regulated by pulmonary impedance characteristics. We focused on the native impedance characteristics variation in the pulmonary circulation. To examine the effect of respiratory control on pulmonary resistance, we measured pulmonary arterial pressure and flow in adult goat under the different respiratory settings with open/closed-chest condition. Pulmonary input impedance in two respiratory conditions under the anesthetized open-chest positive pressure ventilation (PPV) and the awake spontaneous respiration (SR) were calculated. Longitudinal impedance at 0 Hz in SR showed lower than in PPV, and at high harmonic area in SR was bigger than in PPV. In order to examine the hemodynamic response for newly designed artificial internal organs, pulmonary impedance variation caused by respiratory control should be considered. For sophisticated pulmonary resistance model, reproducing the negative pressure condition in the thoracic cavity, and pulmonic vascular resistance regulation might be required.

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Hemolysis test has been used to predict the hemocompatibility of blood pump. However, many factors can influence the results of hemolysis index. Blood viscosity will change by shear stress, and hemolysis induced by shear stress in blood pump. Pump drive condition varies with the change of blood viscosity. Only load condition of pump is prescribed by ASTM and blood viscosity has been not considered. In this study, the influence of blood viscosity on NIH will be investigated. Using fresh porcine blood, which was diluted with dextran 40 and 0.9% saline, we made two kinds of test blood which varied in viscosity at the same hematocrit (Ht). The hemolysis tests were performed in the same load condition using an equivalence pump. In addition, we also made two kinds of test blood which varied in Ht with the same viscosity. The hemolysis tests were performed. When blood viscosity was different, the difference of NIH was observed. In the condition which has the same blood viscosity and load condition, the significant difference was not seen in NIH. From the result, it's considered that it's necessary to match blood viscosity, rather than match Ht for the adjustment of blood in hemolysis test.

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The main purpose of this study is to develop a minimally invasive mechanical circulatory support (MCS) device which can perform renal-selective blood perfusion (RSP) with low invasion on ischemic kidney. In this study, we developed a catheter-based miniature blood pump for MCS device and evaluated its hydrodynamic performance.The miniature blood pump consisted of an impeller, a brushless DC motor, a motor housing and a pump casing and ejects the blood by rotating the impeller which was installed inside the pump casing by the brushless DC motor. The miniature blood pump has two outlet ports against one inlet port for assisting both renal arteries at the same time. The diameter and total length of the prototype pump was 9 mm and 37 mm, respectively. The pump performance of the prototype miniature blood pump was assessed by in vitro testing using a mock circulation circuit. A flow rate of 1 L/min for a 30 mm Hg pressure head was achieved at rotational speed of approximately 20,000rpm. The prototype pump displayed sufficient performance for assisting both renal arteries.

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Fontan procedure is the final palliative surgical operation in pediatric patients with congenital heart disease. After Fontan procedure, there is non-pulsatile flow in the pulmonary circulation. We have been developing the pulmonary circulation assist device for the Fontan circulation using shape memory alloy fibers. The device structure is mechanically contraction from the outside of the extracardiac conduit. For clinical application of the device, we have been also developing the animal experimental model for in vivo examination of the Fontan circulation assist device. In this study, we examined the hemodynamics change in the device driving the animal experimental model. The animal experimental model was constructed in four adult goats (45.8±15.6 kg). The right heart bypass of inferior vena cava to pulmonary artery was constructed by using extracardiac conduit, and the left ventricular assist device was connected to reduce of left ventricular load. The device could be mounted easily to the conduit in the thoracic cavity. The pulsatile flow could be generated in the pulmonary circulation by the device contraction. We performed the evaluation of the pediatric pulmonary circulatory assist device in the animal experimental model.

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Transcutaneous energy transmission system (TETS) was studied in order to realize a complete implanted artificial heart. A electromagnetic induction coupling was used in most TETS. Because the living body can be considered as a conductive and a dielectric material, it is possible to drain a high frequency current through direct or capacitive coupling into the body. In this study, We studied possibility of the high frequency current energy transmission through direct of capacitive coupling. A direct or capacitive coupling TETS was developed using two 2 cm square aluminum foils as electrodes of the TETS. For capacitive coupling TETS the electrodes covered with polymethl pentene film. A energy transmission test was performed using a meat as a phantom, a 4 MHz frequency and 500 Ω impedance power supply, a rectifying circuit and resistance load. Transmission electricity decreased to nearly 10% with 500 Ω load, however it remained in 80% with 5 Ω load. A cause of low transmission efficiency seems that the high frequency current passed through not only the resistance load but also the phantom. For improvement of the transmission efficiency, the electrode shape is resigning and the high frequency power supply impedance is adjusting.

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Rotary blood pumps are commonly employed as circulatory support, which might cause changes in circulation in end organs. The purpose of this study was to develop a noninvasive and contactless system for measurement of peripheral perfusion by using a high-speed camera. A measurement system was designed to derive the amplitude of the green level (AGL). The static test of colour intensity was performed in vitro to verify the blood volume density in the materials. We employed a volume density model, which consisted of a polymer sponge under the different absorption condition using fresh goat blood. The sponge with blood was sandwiched between acrylic plates and the gap between them was varied by the linear table so that the density could be evaluated. The intensity of CCD data on the top flat plate was captured and analysed. As a result, the relationship between the density of blood and the CCD intensity could be evaluated under the LED lighting conditions. Therefore, it was indicated that the AGL could be reflected by the blood volume and the system by using a high-speed camera might be useful for measuring patients' perfusion under the pump support condition.

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Congenital heart disease as represented by Tetralogy of Fallot (TOF) and Transposition of great arteries may be dysfunction at right heart circulation.Surgical procedure for these cardiac arrest using pulmonary valve made from ePTFE is attracting attention. Clinical result in Japan, surgical procedure using pulmonary valve made from ePTFE is better than using biological valve in terms of thrombus formation and calcification. In order to design this valve, we need know behavior of valve cusp made from ePTFE. This valve is widely applied to clinical site and needed high-performance and high-durability. In this study, we discuss objective assessment for reduce right heart strain by improving pulmonary regurgitation base on high-precision analysis of valve cusp behavior. We manufacture reciprocating motion apparatus for analysis of valve cusp behavior under any flow condition and certain pressure load and studied mechanical characteristic of valve.

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Implanted devices such as pacemakers use a battery for a power supply. As a result, the people using the pacemaker must have operation periodically to change a battery. Therefore energy harvesting technology is effective in this field. In this study, we proposed electrical power harvesting from optical energy for implantable devices, and we have tried to find techniques for stable electricity supply using the solar cell in the living body .For the first evaluation of this study, we measured the basic property of the film-type solar battery. As a result, the output of 1500μW was provided. Secondly, we measured the output provided from a solar battery implanted under the skin of the living rat. It supplied 500μW. however, the output decreased considerably a day after implanting because of reaction to foreign body. We solved this problem by using a small spherical solar cell. An implanted cell could generate 50µW. The results of the study show that enough electricity was provided to operate implantable devices such as pacemakers.

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When one need measurement, signal acquisition and wireless transmission, the electronics inevitably needs an adequate supply of operating power. In case of intra-corporeal telemetry device, unless fed extra-corporeally by other means, the operating power must be supported by a local battery there. In this study we devised an intra-corporeal battery system using body fluid available there as presiding electrolyte, to make obvious electronic component “battery” unnecessary in a capsule type sensor-telemeter transmitter. It employs a pair of electrode, magnesium for negative and silver-silver-chloride or carbon positive, placed across the surface of the plastic capsule. Their electrochemical potential difference causes an in-situ primary battery, for example, 1.2V～1.7V, 10～20 microampere capability. A model capsule about 6mm dia. and 12mm length having such electrode cylinders pair electrically separated over core plastic material (poly-oxymethylene(POM), also called poly-acetal or Delrin). In physiological saline water or human urea, the model device operated successfully for more than 24 hours continuously, to conclude a positive feasibility for practical use.

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(Introduction) The endoscope is used in not only the diagnosis but also the treatment in every medical field and the use frequency is increasing remarkably. The data volume increases, the burdens to endoscopists increase. (Purpose) We have proposed that the diagnosis support system to reduce this burden. The endoscopists diagnose from color information. However even the same tissue is seen as different color of the mucosa when viewed from far distant and near view. But it is a change of brightness, color information should be the same. However, it is a change of the brightness, and the color information should be the same. Therefore we paid our attention to HSV coordinates which distributed color (hue: wavelength of the light) and brightness (value) definitely. Then we confirmed the color reliability of HSV coordinates. (Method) The endoscopic image is displayed as RGB image. It is easy for computer to convert into HSV coordinates. The spectral image was calculated by a virtual spectrum from the same image. (Results) The color information of HSV indication was the almost same as at any distance of endoscope position. So we will apply this HSV indication to image processing.

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(Introduction) Frequency of use of the endoscope increased significantly in medical field. Then this increasing amount of data have made burden on endoscopists. The new diagnostic equipment such as the capsule endoscope will make amount of data for diagnosis increase be more huge. (Purpose) The endoscopists diagnose by the information of morphological and color change in every two-dimensional endoscopic images. So we propose the support system diagnosis to reduce this burden. Concretely we have been trying to make the system which can automatically extract a disease area. (Method) As for the endoscopic image, the color information such as blood vessels is made superposition onto the main red mucosa color. And the special structure and color of disease are added to image. The color information is extracted from the virtual spectral image method and structural information from the statistical processing. (Results) It was an automatic diagnosis positive rate of approximately more than 70% in about 100 disease lesion images. We will study the image processing for automatic diagnosis positive rate of more than 80%.

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Endoscopy measuring three-dimensional (3D) shape of organ inner wall is addressed. It can provide organ surface shape and texture simultaneously and improve diagnosis capability such as to find small gastric submucosal tumors. Some endoscpic systems based on stereo measurement or laser scanning have been proposed for this purpose, however, they have the drawbacks of corresponding unstability and occulusion between stereo images. In this paper, we demonstrate 3D shape measurement with single lens endoscopy by a new shape-from-focus (SFF) method that compensates error caused by blur spatial non-uniformity. Our system improved organ shape measurement from 1.38 mm to 0.53 mm RMS error.

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Purpose: We have been developing a navigation system using augmented reality technology and have reported clinical application in laparotomy for the system. We here report our commencing of the clinical application of the system to laparoscopic surgery and building a system fitted for laparoscope. Method: We conducted the clinical application to a case of laparoscopic hepato-biliary-pancreatic surgery.We conducted the operation using 3D super impose display. We examined the system's accuracy and usability. Result: In cases of deformation, anatomical deviation and fixed organ, the navigation was useful in comprehending blood vessels.We calculated its accuracy by FRE and average accuracy was 7.0mm. Even in the liver, we were able to set up various points by using a tool with a geometrical pattern . In addition, we developed the system so that we could repeatedly achieve registration in a short period. Conclusion: Although the laparoscopic navigation surgery has room to improve in registration method and accuracy, we discovered that there is a possibility of improving surgical efficiency by repeating registration and without the need to correspond to the change in target organs.

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A handy switch interface has been developed to allow a single surgeon in a sterilized area to control a locally operated forceps manipulator with five-DOFs. The proposed ergonomic interface is designed based on the size and the moving area of human hand, and the two-point discrimination threshold of gloved finger. Three prototypes made by a 3D printer were a double trigger type, a separate type and a cross-shaped push type. They could be attached to commercial forceps and be pushed some switches at a time. The control time and the assignment of switches were evaluated while performing a task model approved by the ethics committee at Osaka Institute of Technology.

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In laparoscopic surgery, the decision of where to set up the port position on the abdominal wall to inject surgical instrument has an impact on the ease of surgery. When setting up ports in 2 places, it is said that the position of the ports and the surgical target part should form close to a regular triangle as much as possible. But it is difficult to confirm the 3D shape of a triangle during surgery and much is dependent on the surgeon's experience.We have developed a navigation system using AR technique. We applied this technology to develop a system that supports to determine port positions. The system overlays the 3D triangle onto the patient's abdominal region as a stereoscopic image.

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Pancreatic juice leakage to internal as well as external by distal pancreatectomy reported in recent studies.Method to suppress the leakage of internal pancreatic juice has not yet been established. Objective of this study is to visualize pancreatic juice distribution in pancreatic internal resulted from compression by using MRI and to evaluate quantitatively. First, isolated pig pancreas was observed by MRI. After observation, pancreas was compressed for 3 minutes by using a jig without moving the position. After 1 hour of compression, the image of pancreas was acquired by MRI. Then, the image before and after compression was compared. Imaging method was T2-weighted method to emphasize liquid by using the scanner of open type 0.2T MRI. Pancreas had been taken in a plane perpendicular to the jig to observe the effect of compression with 2.5mm spacing.As the result, at the position the white observed part did not exist before compression it is observed after compression.The position of the fat does not move by compression.Then, the white observed part which changes were observed it is inferred to be pancreatic juice.

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In liver cancer surgery, it is crucial to understand the internal structure of the liver, such as the position of tumors, blood vessels and their relationship. 3-dimensional rendering based on pre-operative CT volumes is one of methods for assisting a surgeon to understand such information. However, it is still not enough to achieve intuitive understanding. To solve such problems, this paper demonstrates a method to fabricate 3D liver model from patient-specific CT volumes. This model reconstructs internal structures of the liver to enable intuitive understanding of anatomical structure. Figure shows an example of the 3D liver model and a scene of 3D liver model utilization in OR.

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CT colonography (CTC) is performed for polyp diagnosis. If a polyp is found during CTC, optical colonoscopy is performed. It is expected to develop a navigation system that navigates the optical colonoscope to the place of polyp found by CTC. To achieve such system, we present a method that registers the colonoscope shape and the colon shape for estimating the colonoscope tip location in the CT coordinates. The colonoscope shape is obtained by an electromagnetic tracking device. Both shapes are represented as curve lines and registration is performed by an ICP-based method. Phantom-based experiments revealed good tracking performance enough for assisting colonoscopic examination.

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In this paper, we present anatomical name display function in a laparoscopic surgical navigation system. Laparoscopic surgery navigation system provides virtual laparoscopic views synchronized with the laparoscope motion using a 3D positional tracker and preoperative CT images. We implemented the anatomical name display function showing blood vessel names or manual annotations on the virtual laparoscopic views in the navigation system. We performed surgical navigation during laparoscopic gastrectomy. The proposed navigation system could display the virtual laparoscopic views with anatomical name of blood vessels in synchronization with the laparoscope position.

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The safety of robotic and endoscopic surgeries could be improved if the physical state of organs were evaluated quantitatively during procedures. Although force measurement systems have been investigated, understanding the intraoperative state of an organ remains problematic. We propose a method to reconstruct external forces and the whole deformation field of elastic bodies using local displacement observations. We introduce an L1-norm minimization approach into the finite element analysis to solve the ill-posed problem. Our experiments show that the position and magnitude of the applied force can be reconstructed from 20-30% surface area of the deformed shape.

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Presentation of various softness feeling of complicated multilayer anatomical structures has been required for the medical robots. However it has not yet been realized, because the model of a physical and physiological multilayer softness has not been made. In order to build the physical model, it is necessary to measure the contact area, the pushing depth, and the reaction force. In order to measure them, subjects' finger touched hard or soft single-layer jellies and touched the double layer jellies of which upper layer was soft or hard, respectively in this experiment. The results showed that the three parameters' relationships were different from each four jellies' ones.

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We aim at developing a surgical navigation system which can be controlled by an operating surgeon with his/her voice. This research improves the user interface of the system through implementing a feedback window which shows the speech-recognition state of the system to the surgeon. For more details, the feedback window provides information about whether voice-activated control is available as well as the result of speech recognition, as shown in the figure. We evaluated the proposed system through a clinical test, and then obtained some positivecomments on the usefulness of the feedback window. Therefore, we confirmed the effectiveness of the proposed system.

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We have been developing a surgical navigation system that combines the 3-D image processing system called NewVES and an optical positional tracker. This system performs the following functions for enabling surgical navigation: (a) detailed 3D virtual laparoscopic image (3D-VLI) generation from pro-operative CT volumes, (b) continuous tracking of laparoscope position and posture by the optical tracker, and (c) real-time rendering of 3D-VLIs corresponding to the endoscope view. This system has been utilized for 50 cases of laparoscopic gastrectomy. Recently, stereo laparoscope system has become common in the clinical field. This can provide a surgeon depth cues during surgery. We have developed the stereo navigation system by extending the function of NewVES software. This system renders stereoscopic views in side-by-side format and transmits them to the stereo monitor of the stereo laparoscope system. Surgeons can watch stereo navigation images with the same 3D glasses of laparoscope system. In laparoscopic gastrectomy, we confirmed the system was very useful to understand anatomy of organs and blood vessels which were hard to perceive on 2D navigational display. We believe it will reduce the surgeons' stress during surgery.

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This study describes a visual servo system using biplane ultrasound imaging using a phased array probe which can provide two cross-sectional images in 20 fps. Using the probe, we developed a robotic visual servo system which tracks a target in human body. The probe was attached with the developed robot with six pneumatic actuators. First, a target in the XY and YZ plane is selected as templates. Then, the target 3D position is estimated by template matching of both the XY and YZ images. Finally, the probe is moved to the position. Phantom and porcine liver tests were performed for validation. From the results, the system can track the targets in 1/16 Hz rotation motion with 20 mm diameter.

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Reduction in the number of surgeons is becoming a problem. It calls for urgent attention to build an effective education system as large amounts of knowledge, skill and experience is needed to train surgeons. This time, we have developed an imaging system that integrates synchronously taken images from various angles, not only from the existing surgical camera but also from fixed camera and wearable cameras on both the surgeon and the assistant. We could analyze and evaluate surgical technique by the imaging system. This surgical recording system which can obtain more information compared to existing single viewpoint image is likely to contribute to enhancing not only the techniques of surgeons but also staff at the surgical floor.

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Medical malpractice is a social problem. What is hoped for in technical development is decreasing the burden on the nurses, while at the same time, improving the quality of surgery. Therefore, this study aims to develop a gauze counting system that could be used in operating rooms for the purpose of preventing foreign body remnants and supporting the nurses. The results of automatically counting ten gauzes, the prototype of this system that had been developed, demonstrated 99% accuracy between number of gauzes and output from the system in detecting dried gauzes which had blood adhering to it. It suggested that the precise counting of gauzes could be realized by using this system.

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The combination treatment system of cryosurgery and hyperthermia treatment was fabricated. The system consists of Peltier device, a power supply, a coolant chamber, Stirling cooler and a peristaltic pump. In the system fabrication, an aluminum box was mechanically worked and was attached to Stirling cooler and two pipes with a thermally-conductive bond. In the fabrication of the surgical probe, two pipes and Peltier device were respectively attached to two circular plates. The surgical probe was produced by fixing these plates to PVC pipe. Finally, the coolant chamber and the probe were connected utilizing the cold-resistant tube used at a peristaltic pump. Thus, the combination treatment system was fabricated. The system performance was evaluated using ethanol as a coolant in no-load running condition. During the test, a power was supplied to Peltier device and temperatures were measured. In the results of temperature measurement, the probe temperature reached to -45 degrees C and repeated the process of the cooling and the heating, alternately and continuously. This work was partly supported by JSPS Grants-in-Aid for Young Scientists (B) number 26820065.

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Recently, a surgical treatment, radiation therapy and chemotherapy are performed as a treatment for the tumor tissue.Cryosurgery and hyperthermia treatment is taken as one of the low-invasive therapeutic method. In the past, we have developed the combination treatment system as a test machine of cryosurgery and hyperthermia treatment and have evaluated the system performance. In this study, a handpiece type device for cryosurgery and hyperthermia treatment was produced. The system consists of Peltier device, a handpiece with coolant and stabilized DC power supply. The basic performance of the treatment system was evaluated. In the evaluation, the system was examined using various coolants in the no-load running. During the test, the temperature of the operation side of Peltier device was measured using T type thermocouple. The minimum temperature of the operation side using an urea ammonium sulfate mixture as coolant was lower than that of ethanol. As described above, the enhancement of refrigeration performance of the system would be confirmed.

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Experiments to investigate dissection ability and lifetime of spark electrodes as water jet generator were conducted in present study. Performance of a generator was evaluated pressure measurement with piezoelectric pressure transducer. 0.3 mm diameter Piano wire was used as opposite electrode. Reactor of underwater discharge was 400-power diluted saline. 0.2 uF capacitor, power supply of 5.94 kV and mechanical relay were used for discharge. Nozzle was stainless tube of 0.9 mm diameter and 20 mm length. Based on our preliminary studies, present experiments tried to explain on following; Relationship between counts of spark and pressure of jet with 3.5 mm of electrode gap, and pressure and measuring position with electrode after 50-75 counts of spark.Pressure was almost stable with 3.5 mm of gap until 80 counts. Hence, we can estimate that dissection ability of the jet can be kept in the range of 40-180 counts. In relationship between pressure and measuring position, measured pressure at 2 mm from nozzle tip was higher than at nearer position from nozzle tip. We anticipate that multistep jet was produced, and pressure is higher at an interaction point of several jets.

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Because of its less invasiveness and faster expectation of postoperative recovery, laparoscopic surgery is replacing the traditional open surgery. Also, the benefits of shorter hospitalization, less pain, and better cosmetic results support the increasing use of the laparoscopic surgery. However, the current surgical instruments may cause internal interference with other instruments during the operation and blind spot may occur due to its mechanical structure. To solve these clinical problems, we have been developing a multi-joint manipulator using smart materials called magneto-rheological elastomers (MRE) for the use of laparoscopic-assisted surgery. It consists of a MRE joints, electric coil for generating the magnetic field, housing, flexible tube, and wire. MRE has been known for its unique physical characteristics, i.e., variable stiffness controlled by the applied magnetic field. The previously reported studies were mainly about properties of shearing direction. In our manipulator, however, compressive load will be applied to MRE. In this study, therefore, we investigate the compressive stiffness properties of MRE changing the strength of the magnetic field applied.

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In general anesthesia (GA) using the semi-closed ventilation, carbon dioxide (CO2) needs to be removed from the expired gas by absorber. The primary factor that determines the amount of CO2 recirculation is the fresh gas (FG) flow rate. The purpose of this study is to design a semi-closed ventilation model and quantitatively analyze the effect of the FG flow rate on the CO2 absorption during GA. Methods: The ventilation process is modeled as follows. During the inspiration, FG is blended with recycled gas from the bellows and sent to patients. The gas from the bellows passes the absorber, and CO2 is eliminated before mixing with the FG. During the expiration, the expired gas and FG is stored in the bellows. Once the bellows is filled, the spillover gas is scavenged into the draining system. The simulation program was developed, and the amount of CO2 absorption was calculated as per varied ventilation settings. Results: The simulation demonstrated that the CO2 load on the absorber increases in a non-linear manner as the FG flow rate decreases. This simulation model can be used to measure the cost-effectiveness and environmental impacts of different ventilation settings during GA.

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The purpose of this study is development a blood collection assistant system for accident prevention. In the previous studies, a vein detection system by using absorbance of the hemoglobin, a needle puncture system by using the peak detection of puncture force and blood detection by electrode were developed and integrated. In this study, needle posture control following arm posture was performed with posture markers placed on a NIR-illuminator for vein detection. The arm angle was calculated from the relationship of distance between camera and each marker in the captured image. Experiments were performed to evaluate the accuracy of needle posture control for angle, position and direction according to the arm. As the results, maximum error of control was 6°, 2.8mm and 2.2° in the angle, position and direction, respectively. It seemed that the accuracy of position control was enough for needle puncture to vein of 4mm diameter with 21G needle of 0.8mm diameter. However, improvements of link mechanism and control algorithm were required to reduce the error of angle and direction control.

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We developed a 3D measurement system using digital holography. Our system can reconstruct a 3D shape from a single fringe image by using frequency analysis. Proposed system enables the measurement of 3D shapes of living cells (e.g. red blood cells) which are moving in liquid samples. This paper describes the measurement results of living cells. An experimental result shows that our measurement system can measure the 3D shapes and the movement of living cells in nanometer order. Proposed 3D measurement system based on digital holography is low in price and high in measurement accuracy. This system is expected to become a standard research and inspection tool for medical uses, water quality inspections and many more.

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For Optical Coherence Tomography (OCT) images we propose a new automatic extraction and segmentation of retinal layer structures for assisting ophthalmologists in clinical decision such as diagnosis and treatment. The previous automatic method (One Directional Active Grid; ODAG)) proposed by our group can extract only extracts Inner Limiting Membrane (ILM) and Retinal Pigment Epithelium (RPE). In this paper, we propose a new multi-boundary extraction method, that is, two-step One Dimensional Active Grid (two-step ODAG). The first step is the previous ODAG, and the second step is a new process to extract multi-boundary in retinal layer. We set the initial position of nodes between ILM and RPE, and we are developing a new operation window to detect multi-boundary in the retinal region. We implemented our proposed system by C language and OpenCV library on MS-Windows. We evaluated the accuracy for 10 normal OCT images, and the accuracy is 90%.

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Recently, region-setting CT has been studied as an ROI imaging method. This technique can obtain ROI image and strongly reduce the exposure dose by limiting the irradiation field. In this study, we developed three-dimensional region-setting CT and performed basic evaluations. The 6-channel collimators were controlled independently; it truncates projection data. Captured data were corrected using the mean pixel value of the valid data. The ROI image was reconstructed using the FDK algorithm. In the experiments, the image quality, shape reproducibility and exposure dose distribution were evaluated. These results indicate that proposed system may be useful for dose reduction in CT examination.

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Medical imaging devices have been widely used in clinical medicine to support diagnosis. Doctors need a lot of time and experience for the interpretation of a huge number of images before a screen or monitor to find the lesion candidates without any overlook. In order to reduce the reading time, effective image analysis algorithms, and software tools are expected by Picture Archiving and Communication System (PACS) that commonly used for image interpretations. Computer-aided diagnosis (CAD) system has been expected as a sufficient solution by detecting the lesion candidates, however, the performance and accuracy of CAD are still not good enough for practical applications. In the other hand, the fundamental part of CAD can provide the robust recognition results of the anatomical structures on CT images. Those information maybe useful but still not evaluated on PACS. In this study, we use the anatomical structures that recognized automatically by a CAD to improve the efficiency of torso CT image interpretations on a PACS. We confirmed that our improvements can simplify the operations of PACS and reduce the reading time of CT image interpretations without any loss on accuracy.

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X-ray computed tomography (CT) is widely used in the field of medicine for diagnostic purposes, but the radiation dose to which the patient is exposed must be kept to a minimum. Grids are used to eliminate the harmful scattered radiation that occurs with current X-ray CT machines. However, because objects cause scattered radiation, information about the objects can be extracted from it. Using the Monte Carlo method to calculate the amount of scattered radiation, we constructed a maximum likelihood method to estimate its attenuation coefficient. The accuracy of the estimation was evaluated by the mean square error between the estimated value and the true value. Numerical simulation showed that the accuracy of the estimated attenuation coefficient improved without increasing the radiation exposure dose by utilizing the scattered radiation.

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