Kazuya Nakayama

Nonvolatile SRAM based on Phase Change

We propose a novel architecture (phase change nonvolatile SRAM: PNSRAM) combining SRAM with PRAM. This architecture is possible solution to reduce the program cycle at the nonvolatile material to be divided a program sequence into volatile and nonvolatile. In this paper, we describe the PNSRAM architecture and a circuit simulation results of the volatile and nonvolatile operation

Evaluation of pulmonary function using breathing chest radiography with a dynamic flat panel detector : Primary results in pulmonary diseases

Objectives:Dynamic flat panel detectors (FPD) permit acquisition of distortion-free radiographs with a large field of view and high image quality. The present study was performed to evaluate pulmonary function using breathing chest radiography with a dynamic FPD. We report primary results of a clinical study and computer algorithm for quantifying and visualizing relative local pulmonary airflow. Materials and Methods:Dynamic chest radiographs of 18 subjects (1 emphysema, 2 asthma, 4 interstitial pneumonia, 1 pulmonary nodule, and 10 normal controls) were obtained during respiration using an FPD system. We measured respiratory changes in distance from the lung apex to the diaphragm (DLD) and pixel values in each lung area. Subsequently, the interframe differences (D-frame) and difference values between maximum inspiratory and expiratory phases (D-max) were calculated. D-max in each lung represents relative vital capacity (VC) and regional D-frames represent pulmonary airflow in each local area. D-frames were superimposed on dynamic chest radiographs in the form of color display (fusion images). The results obtained using our methods were compared with findings on computed tomography (CT) images and pulmonary functional test (PFT), which were examined before inclusion in the study. Results:In normal subjects, the D-frames were distributed symmetrically in both lungs throughout all respiratory phases. However, subjects with pulmonary diseases showed D-frame distribution patterns that differed from the normal pattern. In subjects with air trapping, there were some areas with D-frames near zero indicated as colorless areas on fusion images. These areas also corresponded to the areas showing air trapping on computed tomography images. In asthma, obstructive abnormality was indicated by areas continuously showing D-frame near zero in the upper lung. Patients with interstitial pneumonia commonly showed fusion images with an uneven color distribution accompanied by increased D-frames in the area identified as normal on computed tomography images. Furthermore, measurement of DLD was very effective for evaluating diaphragmatic kinetics. Conclusions:This is a rapid and simple method for evaluation of respiratory kinetics for pulmonary diseases, which can reveal abnormalities in diaphragmatic kinetics and regional lung ventilation. Furthermore, quantification and visualization of respiratory kinetics is useful as an aid in interpreting dynamic chest radiographs.

Development of functional chest imaging with a dynamic flat-panel detector (FPD)

Dynamic FPD permits the acquisition of distortion-free radiographs with a large field of view and high image quality. In the present study, we investigated the feasibility of functional imaging for evaluating the pulmonary sequential blood distribution with an FPD, based on changes in pixel values during cardiac pumping. Dynamic chest radiographs of seven normal subjects were obtained in the expiratory phase by use of an FPD system. We measured the average pixel value in each region of interest that was located manually in the heart and lung areas. Subsequently, inter-frame differences and differences from a minimum-intensity projection image, which was created from one cardiac cycle, were calculated. These difference values were then superimposed on dynamic chest radiographs in the form of a color display, and sequential blood distribution images and a blood distribution map were created. The results were compared to typical data on normal cardiac physiology. The clinical effectiveness of our method was evaluated in a patient who had abnormal pulmonary blood flow. In normal cases, there was a strong correlation between the cardiac cycle and changes in pixel value. Sequential blood distribution images showed a normal pattern at determined by the physiology of pulmonary blood flow, with a symmetric distribution and no blood flow defects throughout the entire lung region. These findings indicated that pulmonary blood flow was reflected on dynamic chest radiographs. In an abnormal case, a defect in blood flow was shown as defective in color in a blood distribution map. The present method has the potential for evaluation of local blood flow as an optional application in general chest radiography.

Qualitative near-infrared vascular imaging system with tuned aperture computed tomography

We developed a novel system for imaging and qualitatively analyzing the surface vessels using near-infrared (NIR) radiation using tuned aperture computed tomography (TACT(®)). The system consisted of a NIR-sensitive CCD camera surrounded by sixty light emitting diodes (with wavelengths alternating between 700 or 810 nm). This system produced thin NIR tomograms, under 0.5 mm in slice thickness. The venous oxygenation index reflecting oxygen saturation levels calculated from NIR tomograms was more sensitive than that from the NIR images. This novel system makes it possible to noninvasively obtain NIR tomograms and accurately analyze changes in oxygen saturation.

CoOx-RRAM memory cell technology using recess structure for 128Kbits memory array

This paper presents the process integration and device technology for the Resistance RAM(RRAM) memory array using a CoOx film and a recess structure as a resistor, which is capable of low voltage, high speed and low current operation. The resistance of the CoOx film and its uniformity are strongly dependent on the film quality, which is optimized by controlling the O2 gas flow rate during the film deposition. We demonstrate the basic write and read operation of the 128Kbits memory array by developing the novel process integration technology and optimizing the test algorism.

Heating rate dependence of phase transition temperature in Se7Te3 glasses

The crystallization and the glass-transition temperatures, T c and T g , of Se 7 Te 3 glasses were measured at heating rates of 10 -2 to 10 2 °C/min. T c and T g exhibit weak heating-rate dependences at low heating rates, but the slopes of their heating-rate dependences become steep with increasing heating rate. T c and T g as a function of the heating rate are interpreted in terms of nucleation and fragmentation processes in random networks.

Quantification and visualization of relative local ventilation on dynamic chest radiographs

Recently-developed dynamic flat-panel detector (FPD) with a large field of view is possible to obtain breathing chest radiographs, which provide respiratory kinetics information. This study was performed to investigate the ability of dynamic chest radiography using FPD to quantify relative ventilation according to respiratory physiology. We also reported the results of primary clinical study and described the possibility of clinical use of our method. Dynamic chest radiographs of 12 subjects involving abnormal subjects during respiration were obtained using a modified FPD system (30 frames in 10 seconds). Imaging was performed in three different positions (standing, and right and left decubitus positions) to change the distribution of local ventilation by changing the lungs own gravity in each area. The distance from the lung apex to the diaphragm (abbr. DLD) was measured by the edge detection technique for use as an index of respiratory phase. We measured pixel values in each lung area and calculated correlation coefficients with DLD. Differences in the pixel values between the maximum inspiratory and expiratory frame were calculated, and the trend of distribution was evaluated by two-way analysis of variance. Pixel value in each lung area was strongly associated with respiratory phase and its time variation and distribution were consistent with known properties in respiratory physiology. Dynamic chest radiography using FPD combined with our computerized methods was capable of quantifying relative amount of ventilation during respiration, and of detecting regional differences in ventilation. In the subjects with emphysema, areas with decreased respiratory changes in pixel value are consisted with the areas with air trapping. This method is expected to be a useful novel diagnostic imaging method for supporting diagnosis and follow-up of pulmonary disease, which presents with abnormalities in local ventilation.

Development of qualitative near infrared vascular imaging system with tuned aperture computed tomography

We developed a novel system for imaging and qualitative analysis of surface vessels using near infrared (NIR) radiation with tuned aperture computed tomography (TACT®), even if the NIR cannot transmit through thick regions. NIR-sensitive CCD camera was surrounded by sixty light emitting diodes (alternating wavelengths of 700 nm and 810 nm), and could only detect the NIR from the subcutaneous tissue. We obtained multiple near infrared projections of surface vessels at each wavelength in accordance with the optical aperture theory within one second. Then, we created tomograms using the TACT program, and determined the venous oxygenation index (VOI), which reflected the oxygen saturation level, calculated from the image signals at each wavelength. This system produced thinner NIR tomograms under 0.5 mm. The change in VOI after load test calculated from NIR tomograms was more sensitive than that from NIR images without tomography. Our novel system makes it possible to non-invasively obtain NIR tomograms and accurately analyze changes in oxygen saturation.

Development of Optical Computed Tomography for Evaluation of the Absorbed Dose of the Dyed Gel Dosimeter

Optical computed tomography (optical CT) is a reading device of the dyed gel dosimeters. We are developing the optical CT for the evaluation of three dimensional radiation absorbed dose distribution in the dyed gel dosimeters. We made dyed gel with leuco crystal violet and the dyed gel will be contained in vials. The dyed gel dosimeters were irradiated with 10 MV X-ray beam at 100–2000 MU. The optical CT we developed was consists of a liquid crystal monitor VL-176SE (FUJITSU, Japan) as a light source and a camera uEye XS (iDS, Germany). The dyed gel dosimeter was rotated by a step of every 0.9° with the stepper motor ST-42BYH 1004-5013 (MERCURY MOTOR, China) in a water tank and be taken 400 projections per rotation. Volume data was reconstructed from the projection images with the image processing software Plastimatch. The correlation between the absorbed dose and signal values of the dyed gel dosimeters in the reconstructed image was analyzed. The developed optical CT could reconstructed the images of the dyed gel dosimeters and the signal values of the dyed gel dosimeters in the reconstructed images had linear response related to the dose up to 20 Gy.

An observational study comparing the prototype device with the existing device for the effective visualization of invisible veins in elderly patients in Japan.

Objective: To compare the performance on the detection of the invisible veins between our modified prototype device and an existing device in elderly hospitalized patients. Methods: A prospective, cross-sectional, and observational study was performed in the invisible veins in elderly patients. The major variables, skin color near the invisible veins, and diameter and depth of the invisible veins were measured. The vein visualization rate was calculated as the ratio of the visualized veins to the invisible veins by the visualization device. Results: We analyzed 53 invisible veins in the cubital fossa and 56 invisible veins in the forearm in a total of 72 patients (median age, 73u2009years). The visualization rate for our prototype device was higher than that for an existing device in the cubital fossa and the forearm sites. The visualized veins of the prototype device had a higher intensity ratio than that of an existing device. No significant differences were observed in the body mass index, vein depth, and vein diameter of the visualized veins at the cubital fossa and forearm sites. Conclusion: The prototype surpassed the existing device in visualizing the invisible veins. However, the prototype was unable to visualize all the invisible veins. We need to look for ways to reduce noise and to visualize the invisible veins, and the visualization rate of devices needs to be investigated in further association with the percentage of success with actual intravenous access and locating time to vein.