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Masafumi Takafuji,Kakuya Kitagawa,Masaki Ishida,Yoshitaka Goto,Satoshi Nakamura,Naoki Nagasawa,Hajime Sakuma 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.1
Objective: Third-generation dual-source computed tomography (3rd-DSCT) allows dynamic myocardial CT perfusion imaging (dynamic CTP) with a 10.5-cm z-axis coverage. Although the increased radiation exposure associated with the 50% wider scan range compared to second-generation DSCT (2nd-DSCT) may be suppressed by using a tube voltage of 70 kV, it remains unclear whether image quality and the ability to quantify myocardial blood flow (MBF) can be maintained under these conditions. This study aimed to compare the image quality, estimated MBF, and radiation dose of dynamic CTP between 2nd- DSCT and 3rd-DSCT and to evaluate whether a 10.5-cm coverage is suitable for dynamic CTP. Materials and Methods: We retrospectively analyzed 107 patients who underwent dynamic CTP using 2nd-DSCT at 80 kV (n = 54) or 3rd-DSCT at 70 kV (n = 53). Image quality, estimated MBF, radiation dose, and coverage of left ventricular (LV) myocardium were compared. Results: No significant differences were observed between 3rd-DSCT and 2nd-DSCT in contrast-to-noise ratio (37.4 ± 11.4 vs. 35.5 ± 11.2, p = 0.396). Effective radiation dose was lower with 3rd-DSCT (3.97 ± 0.92 mSv with a conversion factor of 0.017 mSv/mGy∙cm) compared to 2nd-DSCT (5.49 ± 1.36 mSv, p < 0.001). Incomplete coverage was more frequent with 2nd-DSCT than with 3rd-DSCT (1.9% [1/53] vs. 56% [30/54], p < 0.001). In propensity score-matched cohorts, MBF was comparable between 3rd-DSCT and 2nd-DSCT in non-ischemic (146.2 ± 26.5 vs. 157.5 ± 34.9 mL/min/100 g, p = 0.137) as well as ischemic myocardium (92.7 ± 21.1 vs. 90.9 ± 29.7 mL/min/100 g, p = 0.876). Conclusion: The radiation increase inherent to the widened z-axis coverage in 3rd-DSCT can be balanced by using a tube voltage of 70 kV without compromising image quality or MBF quantification. In dynamic CTP, a z-axis coverage of 10.5 cm is sufficient to achieve complete coverage of the LV myocardium in most patients.
A d-dot As an Element of Superconducting Devices
Masaru Kato,Hisataka Suematsu,Masahiko Machida,Masaki Hirayama,Takekazu Ishida,Tomio Koyama 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I
A d-dot is the composite structure of a d-wave superconductor and an s-wave superconductor. Spontaneous half-quantum magnetic °uxes appear around the corners of the d-wave supercon- ducting region. Because of the broken time-reversal symmetry of this state, there are always two degenerate states. We show some basic properties of the d-dot and discuss the potential ability of using the d-dot as a two-state device.
A Trial Toward Marine Watch System by Image Processing
Masatoshi Shimpo,Masato Hirasawa,Keiichi Ishida,Masaki Oshima 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-
This paper describes a marine watch system on a ship, which is aided by an image processing method. The system detects other ships through a navigational image sequence to prevent oversights, and it measures their bearings to maintain their movements. The proposed method is described, the detection techniques and measurement of bearings techniques are derived, and the results have been reported. The image is divided into small regions on the basis of the brightness value and then labeled. Each region is considered as a template. A template is assumed to be a ship. Then, the template is compared with frames in the original image after a selected time. A moving vector of the regions is calculated using an Excel table. Ships are detected using the characteristics of the moving vector. The video camera captures 30 frames per second. We segmented one frame into approximately 5000 regions; from these, approximately 100 regions are presumed to be ships and considered to be templates. Each template was compared with frames captured at 0.33 s or 0.66 s. In order to improve the accuracy, this interval was changed on the basis of the magnification of the video camera. Ships’ bearings also need to be determined. The proposed method can measure the ships’ bearings on the basis of three parameters: (1) the course of the own ship, (2) arrangement between the camera and hull, and (3) coordinates of the ships detected from the image. The course of the own ship can be obtained by using a gyrocompass. The camera axis is calibrated along a particular direction using a stable position on a bridge. The field of view of the video camera is measured from the size of a known structure on the hull in the image. Thus, ships’ bearings can be calculated using these parameters.
Isolated Right Ventricular Apical Hypoplasia: A Case Report with 18 Years of Follow Up
Oya Takashi,Kitagawa Kakuya,Kokawa Takanori,Nakajima Hiroshi,Nakamori Shiro,Ogihara Yoshito,Nakata Kei,Ishida Masaki,Ichikawa Yasutaka,Sakuma Hajime 아시아심장혈관영상의학회 2021 Cardiovascular Imaging Asia Vol.5 No.2
Isolated right ventricular (RV) hypoplasia is a rare congenital anomaly in which the apical trabecular component of the ventricle fails to develop. In severe forms of isolated RV hypoplasia, patients usually develop cyanosis early in life and require prompt surgical intervention. Mild forms, however, can be asymptomatic until the development of severe tricuspid regurgitation due to annular dilatation. We report a 50-year-old woman with isolated RV apical hypoplasia who presented to our hospital 18 years ago and was followed with serial imaging studies.