• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.192-194
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• 2002

We present the results on the calibration of iso-center positions using the quality assurance system established at PMRC for determination of center position in X-ray and proton irradiation fields. Details on the system are presented in another presentation in this session. The equipment in the system is mounted on a patient treatment bed in each proton exposure room, G1 or G2. A center of a stainless ball on the equipment is set at a cross of laser markers located around the iso-center and fixed on the room and on the snout in the gantry. A proton beam or an X-ray beam is exposed onto the ball through a brass collimator of 100 mm ${\times}$ 100 mm and projected onto the imaging plate set at I cm behind the ball. On the axis perpendicular to the thrust axis of the gantry on the imaging plate, a distance between a center of the collimator image and a center of the ball image varies as a cosine function of gantry angles unless the ball is set on the iso-center. An amplitude of the cosine curve shows the distance between the ball and the iso-center, an offset the offset of the collimator, and a phase shift at a zero crossing point the ball direction viewed from the iso-center. We present the relation among the iso-center position, the laser maker position, and the center of proton and X-ray irradiation fields. Its stability and its reproducibility are discussed.

• 대한핵의학회:학술대회논문집
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• 2005.11a
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• pp.320.2-320.2
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• 2005

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.85-90
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• 2015

In this study, we investigated the number of categories of veterinary medical devices registered by Animal and Plant Quarantine Agency (QIA) by 2013. We also analyzed the sales of the veterinary medical devices reported from Korea Animal Health Product Association (KAHPA) from 2011 to 2013. The registration rate of veterinary medical devices has sharply increased since 2008, and a total of 495 categories from 141 companies were registered by the end of 2013. The multi-frequency products registered for companion animals were ultrasound imaging system, x-ray system, microchip & reader, telemetry system transmitter, and hematology analyzer. The veterinary medical devices for farm animals include marker, artificial insemination catheter, injector, and ultrasound imaging system. Of these products, the multi-frequency products dominated on the veterinary medical devices market. The market size of 223 (45.0%) veterinary medical devices was estimated to be approximately 20.6 billion Won in 2013; the proportion of domestic products and imports was 56% to 44%; the proportion of domestic demand and export was 82% to 18%, respectively. This study suggested that the registration and sales of the veterinary medical devices have gradually increased as the demand of health care services got bigger in Korea.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.31-39
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• 2018

Purpose: This study aimed to evaluate the effect of field-of-view (FOV) size on the gray values derived from cone-beam computed tomography (CBCT) compared with the Hounsfield unit values from multidetector computed tomography (MDCT) scans as the gold standard. Materials and Methods: A radiographic phantom was designed with 4 acrylic cylinders. One cylinder was filled with distilled water, and the other 3 were filled with 3 types of bone substitute: namely, Nanobone, Cenobone, and Cerabone. The phantom was scanned with 2 CBCT systems using 2 different FOV sizes, and 1 MDCT system was used as the gold standard. The mean gray values(MGVs) of each cylinder were calculated in each imaging protocol. Results: In both CBCT systems, significant differences were noted in the MGVs of all materials between the 2 FOV sizes(P<.05) except for Cerabone in the Cranex3D system. Significant differences were found in the MGVs of each material compared with the others in both FOV sizes for each CBCT system. No significant difference was seen between the Cranex3D CBCT system and the MDCT system in the MGVs of bone substitutes on images obtained with a small FOV. Conclusion: The size of the FOV significantly changed the MGVs of all bone substitutes, except for Cerabone in the Cranex3D system. Both CBCT systems had the ability to distinguish the 3 types of bone substitutes based on a comparison of their MGVs. The Cranex3D CBCT system used with a small FOV had a significant correlation with MDCT results.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.309-314
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• 2012

Nowadays, digital Radiography (DR) systems are widely used in clinical sites and substitute the analog-film x-ray imaging systems. The resolution of DR images depends on several factors such as characteristic contrast and motion of the object, the focal spot size and the quality of x-ray beam, x-ray scattering, the performance of the DR detector (x-ray conversion efficiency, the intrinsic resolution). The DR detector is composed of an x-ray capturing element, a coupling element and a collecting element, which systematically affect the system resolution. Generally speaking, the resolution of a medical imaging system is the discrimination ability of anatomical structures. Modulation transfer function (MTF) is widely used for the quantification of the resolution performance for an imaging system. MTF is defined as the frequency response of the imaging system to the input of a point spread function and can be obtained by doing Fourier transform of a line spread function, which is extracted from a test image. In clinic, radiologic technologists, who are in charge of system maintenance and quality control, have to evaluate or make routine check on their imaging system. However, it is not an easy task for the radiologic technologists to measure MTF accurately due to lack of their engineering and mathematical backgrounds. The objective of this study is to develop and provide for radiologic technologists a medical system imaging evaluation tool, so that they can measure and quantify system performance easily.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.388-391
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• 2003

The properties of these detectors can be controlled by electronics and exposure conditions. Flat-panel detectors for digital diagnostic imaging convert incident x-ray images to charge images. Flat panel detectors gain more interest real time medical x-ray imaging. Active area of flat panel detector is $14{\times}17$ inch. Detector is based on a $2560{\times}3072$ away of photoconductor and TFT pixels. X-ray conversion layer is deposited upper TFT array flat panel with a 500m by thermal deposition technology. Thickness uniformity of this layer is made of thickness control technology(5%) of thermal deposition system. Each $139m{\times}139m$ pixel is made of thin film transistor technology, a storage capacitor and charge collection electrode having geometrical fill factor of 86%. Using the separate driving system of two dimensional mosaic modules for large area, that is able to 4.2 second per frame. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system..

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.317-323
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• 2001

DICOM(Digital Imaging and Communications in MediCine), standard of medical image operation, present the methods for communications and Storage of Medical Image. medical image acquired from patient in hospital made DICOM files. this paper purposes design and implementation methodologies of a web-based medical information system that consists of DICOM (Digital Imaging and Communications in Medicine) databases and functional components of a web server in order to support the access of medical information with Intemet web browser. we store the patient and image information to database using reading the group and element oJ DICOM file. we made file transfer module by implementing DICOM Store service, in result, we can transfer DICOM file to IF based host or computer. We compose web component of communications and Storage service, user be used DICOM Service by web Browser.

• Imaging Science in Dentistry
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• v.52 no.1
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• pp.11-18
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• 2022

Purpose: This study aimed to assess incidental abnormal findings in the paranasal sinuses and anatomical variations of the ostiomeatal complex (OMC) on magnetic resonance imaging (MRI) scans. Materials and Methods: MRI scans of 616 patients (mean age, 44.0±19.4 years) were evaluated. Prior to obtaining the MRI scans, a checklist of patients' clinical symptoms was filled out after obtaining their consent. The Lund-Mackay classification was used to assess the paranasal sinuses and OMC. The prevalence of abnormal findings and their associations with patients' age, sex, and subjective symptoms were analyzed by the chi-square test, independent-sample t-test, and analysis of variance. The level of significance was set at 0.05. Results: Abnormal findings in the paranasal sinuses were detected in 32.0% of patients, with a significantly higher prevalence in males (P<0.05), but no significant association with age (P>0.05). Epithelial thickening and retention cyst were the most common abnormal findings in the paranasal sinuses. According to the Lund-Mackay classification, 93% of the study population had normal sinuses (score<4). Concha bullosa and paradoxical concha were detected in 15.3% and 3.4%, respectively, with no significant association with the presence of septal deviation or Lund-Mackay classification (P>0.05). Conclusion: Considering the relatively high prevalence of abnormal findings in the paranasal sinuses, it appears that clinical symptoms alone are not sufficient to diagnose sinusitis. A more accurate strategy would be to assess radiographic images of the paranasal sinuses and use a classification system. Sinusitis should be suspected in patients receiving a high score in this classification.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.392-396
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• 2007

In this paper, we develop a new system to visualize the blood flow map in skin tissue, using the technique of Laser Speckle Flowgraphy (LSFG). The measuring unit consists of the laser diode, imaging system, line sensor, scanning mirror, and one-board microcomputer. The speckle signal is analyzed and sent to a PC, where the blood flow in a tissue area of $14mm{\times}26 mm$ is evaluated and displayed in a 2-D color map. It is demonstrated that the new LSFG instrument is useful to evaluate the degree of allergic reaction in patch test.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.485-488
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• 2002

In order to understand and quantitatively analyze the physical phenomena and behavior of each component of mammography system during the breast imaging, we simulated mammography imaging using Monte Carlo simulation codes. MCNP4B code was used for our simulation purpose, and we investigated the effect of target material, anode angle, filtration, peak voltage and exposure on the image quality of mammograms. From the simulation results we expect that optimized operation condition of mammography system can be found.