• The Journal of the Acoustical Society of Korea
• /
• v.28 no.4
• /
• pp.370-374
• /
• 2009

In this paper, we presents a new cone beam computerized tomography (CB CT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time.

• Progress in Medical Physics
• /
• v.26 no.3
• /
• pp.160-167
• /
• 2015

Radiation exposure from medical diagnostic imaging procedures to patients is one of the most significant interests in diagnostic x-ray system. A miniature x-ray intraoral tube was developed for the first time in the world which can be inserted into the mouth for imaging. Dose evaluation should be carried out in order to utilize such an imaging device for clinical use. In this study, dose evaluation of the new x-ray unit was performed by 1) using a custom made in vivo Pig phantom, 2) determining exposure condition for the clinical use, and 3) measuring patient dose of the new system. On the basis of DRLs (Diagnostic Reference Level) recommended by KDFA (Korea Food & Drug Administration), the ESD (Entrance Skin Dose) and DAP (Dose Area Product) measurements for the new x-ray imaging device were designed and measured. The maximum voltage and current of the x-ray tubes used in this study were 55 kVp, and 300 mA. The active area of the detector was $72{\times}72mm$ with pixel size of $48{\mu}m$. To obtain the operating condition of the new system, pig jaw phantom images showing major tooth-associated tissues, such as clown, pulp cavity were acquired at 1 frame/sec. Changing the beam currents 20 to $80{\mu}A$, x-ray images of 50 frames were obtained for one beam current with optimum x-ray exposure setting. Pig jaw phantom images were acquired from two commercial x-ray imaging units and compared to the new x-ray device: CS 2100, Carestream Dental LLC and EXARO, HIOSSEN, Inc. Their exposure conditions were 60 kV, 7 mA, and 60 kV, 2 mA, respectively. Comparing the new x-ray device and conventional x-ray imaging units, images of the new x-ray device around teeth and their neighboring tissues turn out to be better in spite of its small x-ray field size. ESD of the new x-ray device was measured 1.369 mGy on the beam condition for the best image quality, 0.051 mAs, which is much less than DRLs recommended by IAEA (International Atomic Energy Agency) and KDFA, both. Its dose distribution in the x-ray field size was observed to be uniform with standard deviation of 5~10 %. DAP of the new x-ray device was $82.4mGy*cm^2$ less than DRL established by KDFA even though its x-ray field size was small. This study shows that the new x-ray imaging device offers better in image quality and lower radiation dose compared to the conventional intraoral units. In additions, methods and know-how for studies in x-ray features could be accumulated from this work.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.4
• /
• pp.471-480
• /
• 1999

This paper presents design and performance improvement of a new digital tomosynthesis (DTS) system for object-detector synchronous rotation. Firstly, a new DTS system, called OSDR (Object-Detector Synchronous Rotation) is suggested and designed to acquire X-ray digital images. Secondly, the shape distortion of DTS images generated by an image intensifier is modeled. And a new synthesis algorithm, which overcomes the limitations of the existing synthesis algorithm, is suggested to improve the sharpness of the synthesized image. Also an artifact analysis of the DTS system is performed. Thirdly, some performance indices, which evaluate quantitatively performance improvement, are defined. And the experimental verification of the performance improvement is accomplished by the ODSR system newly designed. The advantages of the ODSR system are expressed quantitatively, compared with an existing system.

• Journal of the Korean Society of Radiology
• /
• v.17 no.6
• /
• pp.865-872
• /
• 2023

The purpose of this study was to analyze fabrics suitable for use as examination gowns to determine whether examination gowns affect imaging during anterior to posterior chest examinations(Chest AP) on a digital X-ray system. Examination gowns in use at five medical centers in Seoul were collected and included modal, tencel, cotton, and rayon fabrics. The selection of fabrics was based on studies that reported fabrics with good tactile, absorbent, stretchable, and wrinkle resistance. Phantoms of five hospital gowns and four fabrics, arranged in overlapping layers from one to eight, were created and examined on a digital X-ray system in both Chest AP examination. The images examined were subjected to a first-step profile analysis, a second-step signal intensity averaging analysis, and a third-step microscopic analysis. The results showed that all nine materials had an increasing impact on the image as the number of layers of fabric increased, with the modal fabric having the least impact on the image in the first, second, and third analyses. In conclusion, as the resolution of digital x-ray systems increases, the impact of examination clothing on the image will increase, and research to find suitable materials for examination clothing will continue to be necessary.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.3 s.96
• /
• pp.198-207
• /
• 1999

This paper presents an accurate algorithm for geometric calibration of X-ray imaging system. Calibration is a very important process for improving an imaging system performance. There has been a lot of previous works using linear camera modeling technique, where lens distortion is neglected and/or center of distortion is assumed to be known. Geometrical distortion of image intensifier, however, is very large and its center of distortion should be calculated. This paper presents a new calibration method to estimate the intensifier position and orientation, scale factor, distortion coefficient, magnification factor, and center of distortion using the least square method. We investigate the properties of the algorithm by computer simulation. Simulation results show that the parameters can be estimated accurately using the proposed algorithm.

• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.545-557
• /
• 2009

In order to investigate dynamic damage mechanism of brittle materials, Split Hopkinson Pressure Bar (SHPB) have been adapted to apply different impact levels to rocks in South Korea. High resolution X-ray Computed Tomography (CT) was used to estimate the damage in tested rock samples nondestructively. The cracks which are parallel to the loading axis are visible on the contact surface with the incident bar under lower level of impact. The surface cracks disappeared with increment of impact level due to confined effect between the incident bar and sample, while axial splitting are happened near the outer surface.

• Journal of Digital Convergence
• /
• v.14 no.9
• /
• pp.331-339
• /
• 2016

Chronic diseases are increasing nowadays as daily habits changed due to economic growth. Among chronic diseases, heart cerebrovascular disease is one of the major causes of death in South Korea that accounts for approximately 20% of mortality. Tests to measure anomaly of the heart is ECG tests, which measures and analyzes the electrical heart activity. Any mistakes in lead attachment location critically affects ECG testings, and statistical facts showed that only 2.8% of the nurses properly located leads to patients. As a solution, this paper proposes a system based on a projection-based augmented reality technology to generate X-ray images to the patient's chest to point out exact attachment locations of ECG leads. Evaluation comparison results showed a 2.6 cm difference between the conventional system and the proposed system. ECG test results also showed significant signal differences between the systems in leads V1, V2, and V3. The ECG measured accurately by the proposed system would help greatly in patient management and clinical decisions of clinicians.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.6
• /
• pp.546-552
• /
• 2010

As the demands for the safety and convenience applications of the vehicles increase, the data load for the In-vehicle Network has increased significantly. As a result, a deterministic and fault-tolerant communication system is required to implement the safety critical applications such as X-by-wire systems. FlexRay communication system is a new standard of network communication system which provides the high speed serial communication, time triggered bus and fault tolerant communication between electronic devices. In addition to time-triggered communication, as providing of the event-triggered communication such as CAN, FlexRay protocol is able to manage the restricted communication resource more effectively. This paper presents the development of FlexRay driver which will be applied to the future ECU's communication system. To develop the FlexRay driver, the FlexRay requirement specification and FlexRay specification is analyzed. The developed FlexRay driver is implemented by using MPC5567 microprocessor of the Freescale semiconductor. To verify the developed FlexRay driver, the waveform of the FlexRay driver was measured and compared with the CAN communication system. As a result, the bus load is reduced about 13% compared with the CAN communication system.

• Journal of Korea Society of Industrial Information Systems
• /
• v.23 no.1
• /
• pp.1-12
• /
• 2018

This paper presents a material estimation method using dual-energy X-ray images generated as a result of cargo inspection system in MeV region. We use new discrimination curve using logarithmic function rather than four discrimination curves commonly used in existing estimation algorithms. We also propose an atomic number estimation using the probability distribution of the logarithmic curve rather than linear interpolation. When the probability distribution is used as a weight, we used two methods of using the weight for the two nearest reference materials and the weight for all the reference materials. Experimental results showed that the atomic number estimation of materials using the probability distribution as a weight is more accurate than the existing methods. In order to visualize the estimated atomic number, the HSI model was used for color the resulting image.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.9 no.1
• /
• pp.61-66
• /
• 2015

Chest X-ray images is the most common and widely used in clinical findings for a wide range of anatomical information about the prognosis of the disease in patients with cardiopulmonary rehabilitation. Many analysis algorithm was developed by a number of studies regarding the region segmentation and image analysis, there are specific differences due to the complexity and diversity of the image. In this paper, a diagnosis support system of the chest X-ray image based on image processing and analysis methods to detect the cardiopulmonary disease. The threshold value and morphological method was applied to segment the pulmonary region in a chest X-ray image. Anatomical measurements and texture analysis was performed on the segmented regions. The effectiveness of the proposed method is shown through experiments and comparison with diagnosis results by clinical experts to show that the proposed method can be used for decision support system.