• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.265-270
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• 2007

Polarization imaging systems have been widely used to selectively characterize skin lesions. Nevertheless, current systems are used in single-mode due to the limitations of a fixed polarization mode and a single-working distance of light source, in which uniform light distribution is achieved on target area. To address such limitations, we developed a variable polarization imaging system based on multi-working distance of light source for various clinical diagnoses. In this study, we characterize the imaging system and present experiment results demonstrating its clinical usefulness. The imaging system consists of a CCD color camera, linear polarization filters, and a single-layered LED ring light source which provides uniform light distribution at multi-working distances. The first polarizer was placed on the light source and the second polarizer placed on objective lens provides continuous linear polarization angle from $0^{\circ}\;to\;90^{\circ}$. The clinical efficacy of the imaging system was investigated by acquiring and analyzing clinical images of skin wrinkle and dental plaque. With the experiments, we verified the potential usefulness of the imaging system for other clinical applications.

• Journal of Biomedical Engineering Research
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• v.33 no.3
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• pp.105-113
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• 2012

Biopsy is a type of histopathological examinations, in which a physician samples cells or tissues from a patient's suspicious lesion. Such a lesion frequently resides deep inside human body, and then a percutaneous biopsy is therefore performed using a thick needle with the assistance of medical imaging such as computed tomography(CT) and magnetic resonance imaging(MRI). Recently modern robotic technology is being introduced to percutaneous biopsy in order to reduce any possible human error and hazard on physicians caused by medical imaging. After medical imaging locates the exact location of lesion, an optimization algorithm plans the path for a biopsy needle. Subsequently, a robot system moves the biopsy needle to the lesion in accurate and safe way with the control of a practitioner or automatically. In this article, we try to look into the state-of-art of percutaneous biopsy using such robotic technology. We classified percutaneous biopsy robots by mechanical characteristics and by imaging technology. Then, advantage and disadvantage of each class type are described as well as the basic description, and a few representative designs for each type are introduced. Current research issues of robotized percutaneous biopsy are subjectively selected for the readers' convenience. We emphasize the basic technology of actuator and sensors compatible with imaging technology to conclude this review.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.45-46
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• 2021

의료영상이란 의료영상장비로부터 DICOM이라는 의료영상표준에 따라 저장되며, 의료영상관리 시스템인 PACS를 통해 관리된다. 이러한, 의료영상장비 ICT기술이 융합되어 급격하게 발전되고 있으며 다양한 의료영상장치가 개발되어지고 있다. 하지만, 기술력은 높아지고 있으나 개발된 의료영상장비로부터 촬영된 영상품질관리에 대한 문제점이 제기되고 있다. 이와 관련하여 다기관의 의료영상장비 개발과 해당 기기로부터 수집된 의료영상에 대한 품질을 관리할 필요성이 증가하고 있다. 따라서 코로나 19와 같은 상황에서 의료기기 개발 지원과 관리를 비대면 관리서비스 시스템 개발과 의료영상장치 개발 정도를 관리할 수 있을 뿐만 아니라 의료영상에 대한 품질까지 모니터링하여 및 개선 할 수 있는 시스템을 제안하고자 한다.

• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.20-23
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• 1997

The purpose of this paper is to describe the transition of a 1,100 beds teritary hospital from 50% softcopy operation to full PACS operation. For the past 2 years, radiologists and clinicians have been using PACS to provide softcopy services to the outpatient clinics and inpatient wards of orthopedics surgery, neurosurgery and neurology as well as emergency room, surgical intensive care unit, medical intensive unit, pediatrics intensive care unit and neonatal intensive care unit. The examinations requested by these departments account for about 50% of hospital's radiological exams. In September 1996, we began the second phase of PACS implementation and installed additional workstations (102) in the remaining wards and clinics, interfaced to PACS additional imaging modalites, and increased the capacity of both the image server (256 Gbytes) and optical juke boxes (3 Tbytes). As of January 1997, we are in the final phase of moving away from conventional film system to full PACS operation.

• Progress in Medical Physics
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• v.2 no.1
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• pp.3-16
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• 1991

Abstract. An area of particularly rapid technological growth in the last 15 years has been medical imaging (conventional X-ray, ultrasound, X-ray computed tomography (CT), magnetic resonance imaging (MRI). As the number and complexity of imaging studies rises, it becomes ever more important to distribute these images and the associated diagnoses in a timely and cost-effective fashion. The purpose of this paper is to describe the requirements for a future digital radiology system which will efficiently handle the large volume of images that generated, add new functionality to improve productivity of physicians, technologists, and other health care providers, and provide enough flexibility to allow the system to grow as medical image technology grows.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.294-298
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• 1997

In the magnetic resonance imaging, the fast spin echo imaging technique is a widely used clinical imaging method, since its scanning time is much shorter than the conventional spin echo imaging and it gives the almost same image quality. However, the fast spin echo technique has two times longer imaging time or the dual echo acquisition which can obtain a spin density image and a $T_2$-weighted image simultaneously. To overcome such a drawback, this paper proposes a new fast dual echo imaging technique which can give the same quality images at the single echo imaging time. The proposed technique reduces the imaging time by overlapping most of echo train data for each image reconstruction. In order to verify its validity and usability the human head experimental results which were obtained at the 0.3T permanent MRI system are presented.

• Korean Journal of Radiology
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• v.24 no.8
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• pp.772-783
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• 2023

Objective: Imaging-based survival stratification of patients with gliomas is important for their management, and the 2021 WHO classification system must be clinically tested. The aim of this study was to compare integrative imaging- and pathology-based methods for survival stratification of patients with diffuse glioma. Materials and Methods: This study included diffuse glioma cases from The Cancer Genome Atlas (training set: 141 patients) and Asan Medical Center (validation set: 131 patients). Two neuroradiologists analyzed presurgical CT and MRI to assign gliomas to five imaging-based risk subgroups (1 to 5) according to well-known imaging phenotypes (e.g., T2/FLAIR mismatch) and recategorized them into three imaging-based risk groups, according to the 2021 WHO classification: group 1 (corresponding to risk subgroup 1, indicating oligodendroglioma, isocitrate dehydrogenase [IDH]-mutant, and 1p19q-codeleted), group 2 (risk subgroups 2 and 3, indicating astrocytoma, IDH-mutant), and group 3 (risk subgroups 4 and 5, indicating glioblastoma, IDHwt). The progression-free survival (PFS) and overall survival (OS) were estimated for each imaging risk group, subgroup, and pathological diagnosis. Time-dependent area-under-the receiver operating characteristic analysis (AUC) was used to compare the performance between imaging-based and pathology-based survival model. Results: Both OS and PFS were stratified according to the five imaging-based risk subgroups (P < 0.001) and three imaging-based risk groups (P < 0.001). The three imaging-based groups showed high performance in predicting PFS at one-year (AUC, 0.787) and five-years (AUC, 0.823), which was similar to that of the pathology-based prediction of PFS (AUC of 0.785 and 0.837). Combined with clinical predictors, the performance of the imaging-based survival model for 1- and 3-year PFS (AUC 0.813 and 0.921) was similar to that of the pathology-based survival model (AUC 0.839 and 0.889). Conclusion: Imaging-based survival stratification according to the 2021 WHO classification demonstrated a performance similar to that of pathology-based survival stratification, especially in predicting PFS.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.304-310
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• 2011

Objective : Intrathecal methotrexate (MTX) therapy combined with whole brain radiotherapy (WBRT) is one of the major treatment modalities for leukemia and lymphoma involving the central nervous system (CNS). The purpose of this study was to retrospectively determine the incidences of leukoencephalopathy and disseminated necrotizing leukoencephalopathy (DNL) following intrathecal MTX therapy for CNS lymphoma or leukemia and to assess the potential risk factors. Methods : Between January 2000 and August 2009, 143 patients with CNS lymphoma or leukemia received intrathecal MTX therapy alone or in combination with WBRT at a single institution. Patients were followed up clinically and radiologically at regular two- or three-month intervals. Medical records were reviewed to obtain information regarding the patients' demographics, medical histories, radiologic characteristics, treatments, and clinical courses. Results : On follow-up MR images, leukoencephalopathy was found in 95 of 143 patients (66.4%). The median time to develop leukoencephalopathy was 6.6 months. Among those with leukoencephalopathy, four patients showed seven extensive white-matter changes with strongly enhancing lesions demonstrating DNL. Histological confirmation was done in six lesions of three patients and radiological diagnosis alone in one patient. Four lesions spontaneously disappeared on MR images without any treatment, with a mean duration of 14 months before disappearance of DNL. Conclusion : Leukoencephalopathy is a common phenomenon that occurs following intrathecal MTX therapy; however, DNL occurs at a very low incidence. For newly developed enhancing lesions, consideration for the occurrence of DNL should be taken to avoid unnecessary invasive procedures or therapies.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.25-30
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• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.189-191
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• 2002

In the proton therapy using a gantry system, periodical verification of iso-center position is very important to assure precision of patient positioning system at any gantry angles in proton treatment. In the gantry system, there are three different types of iso-center; 1) in a geometrical view, 2) in an X-ray beam's eye view, 3) in a proton beam's eye view. Idealistically, they would be an identical point. They could, however, be different points. It may be a source of errors in patient positioning. At PMRC, we have established a system of verification for iso-center positions using a stainless ball of 2-cm in diameter and an imaging plate. This system provides the relation among a center of a patient target position, a center of proton irradiation field, and/or a center of X-ray field in accuracy of 50$\square$m in the 2) and 3) views, as images of a center of the stainless ball and a center of a 100 mm${\times}$100 mm-aperture brass collimator recorded on the imaging plate, which is setup at 1-cm behind the ball. In addition, it provides simultaneously the images of the ball and the collimator on an imaging intensifier (II), which is setup downstream of the proton or X-ray beam. We present a method of quality assurance (QA) for calibration of iso-center position in a rotation gantry system at PMRC and the performance of this system. A proton beam position on the 1$\^$st/ scatterer in the nozzle of the gantry affects less sensitive (reduced by a factor of 1/5) to the results of the iso-center position. The effect is systematically correctable. The effect of the nozzle (or the collimator) position is less than 0.5 mm at the maximum extraction (390 mm).