• 한국방사선학회논문지
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• 제8권1호
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• pp.43-49
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• 2014

PACS에서 용량이 큰 의료영상은 대용량 저장장치를 필요로 하고, 느린 전송으로 인하여 PACS의 성능을 저하시킨다. 따라서 판독의에 의해 판독되어진 영상이나 장기간 저장하는 영상의 질을 떨어뜨리지 않고, 추후 판독에 영향을 주지 않는 범위 내에서 압축하여 보관하게 된다. 압축 및 영상 저장 전송 시 발생되는 noise과 영상저장 및 전송 시 발생하는 정보손실 그리고 의료영상을 모니터에서 출력 시 발생하는 화질저하 등 많은 문제점 들이 발생한다. 본 연구는 P사 DSA 시스템의 Server display monitor와 Client display monitor의 PSNR을 평가하여 Server display 신호획득에서 부터 Client display monitor까지의 과정에서 발생하는 PSNR에 대한 평가 및 개선방안을 제안하고자 한다. 실험에 사용한 장비는 P사 DSA를 사용하였다. 혈관조영술 영상을 display하여 실험에 사용한 모니터로는 2가지로써 P사의 해상도 $1280{\times}1024$ 픽셀 모니터와 W사의 해상도 $1536{\times}2048$ 픽셀 모니터를 사용하였다. PACS Program은 MARO-view를 이용하였고 실험을 위해서 Visual $C^{++}$을 이용한 PSNR 측정 Program을 구현하여 실험에 사용하였다. 실험결과 No 1, 3번의 PSNR에 변화가 없는 것은 영상의 전송과 디스플레이 상에 Error가 없는 것으로 나타났으며, 압축률에서는 압축률이 낮은 쪽이 화질저하가 적었고, 영상의 손실 차이가 미미해 압축률에 따른 큰 문제점은 발견되지 않았다.

• Clinics in Shoulder and Elbow
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• 제21권2호
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• pp.82-86
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• 2018

Background: Although a common shoulder disease, there are no accepted classification criteria for frozen shoulder (FS). This study therefore aimed to evaluate the accuracy of the conventionally used FS classification system. Methods: Primary FS patients (n=168) who visited our clinic from January 2010 to July 2015 were included in the study. After confirming restrictions of the glenohumeral joint motion and absence of history of systemic disease, trauma, shoulder surgery, shoulder muscle weakness, or specific x-ray abnormalities, the Zuckerman and Rokito's classification was employed for diagnosing primary FS. Following clinical diagnosis, each patient underwent a shoulder magnetic resonance imaging (MRI) and blood tests (lipid profile, glucose, hemoglobin A1c, and thyroid function). Based on the results of the blood tests and MRIs, the patients were reclassified, using the criteria proposed by Zuckerman and Rokito. Results: New diagnoses were ascertained including blood test results (16 patients with diabetes, 43 with thyroid abnormalities, and 149 with dyslipidemia), and MRI revealed intra-articular lesions in 81 patients (48.2%). After re-categorization based on the above findings, only 5 patients (3.0%) were classified having primary FS. The remaining 163 patients (97.0%) had either undiagnosed systemic or intrinsic abnormalities (89 patients), whereas 74 patients had both. Conclusions: These findings demonstrate that most patients clinically diagnosed with primary FS had undiagnosed systemic abnormalities and/or intra-articular pathologies. Therefore, a modification of the Zuckerman and Rokito's classification system for FS may be required to include the frequent combinations, rather than having a separate representation of systemic abnormalities and intrinsic causes.

• Journal of Korean Neurosurgical Society
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• 제61권4호
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• pp.485-493
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• 2018

Objective : Cerebral varices (CVs) without an arteriovenous shunt, so called nonfistulous CVs, are very rare, and their etiology and natural course are not well understood. The aim of this study is to evaluate the clinical outcomes of nonfistulous CVs by the analysis of 39 cases. Methods : From 2000 to 2015, 22 patients with 39 nonfistulous CVs (${\geq}5mm$) were found by searching the medical and radiologic records of our institute. Clinical data and radiological data including numbers, sizes and locations of CVs and associated anomalies were retrospectively collected and analyzed. Previously reported cases in literature were reviewed as well. Results : The mean age of the patients was 21 years (range, 0-78 years). On average, $1.8{\pm}1.2CVs$ were found per patient. CVs were categorized as either fusiform or saccular depending on their shapes. Two patients had saccular type CVs, seventeen patients had fusiform types, and three patients had both fusiform and saccular CVs. Eight patients had associated compromise of the vein of Galen and the straight sinus. Four of those patients had sinus pericranii, as well. Five patients had CVs that were distal draining veins of large developmental venous anomalies. One patient had associated migration anomaly, and two patients had Sturge-Weber syndrome. Six patients with an isolated cerebral varix were observed. Of the 39 CVs in 22 patients, 20 lesions in 14 patients were followed up in outpatient clinics with imaging studies. The average follow-up duration was 6.6 years. During this period, no neurological events occurred, and all the lesions were managed conservatively. Conclusion : Nonfistulous CVs seemed to be asymptomatic in most cases and remained clinically silent. Hence, we suggest conservative management.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.89-94
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• 2014

Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.

• 제어로봇시스템학회논문지
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• 제19권6호
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• pp.527-533
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• 2013

BCI (Brain-Computer Interface) is a system that transforms a subject's brain signal related to their intention into a control signal by classifying EEG (electroencephalograph) signals obtained during the imagination of movement of a subject's limbs. The BCI system allows us to control machines such as robot arms or wheelchairs only by imaging limbs. With the exact same experiment environment, activated brain regions of each subjects are totally different. In that case, a simple approach is to use as many channels as possible when measuring brain signals. However the problem is that using many channels also causes other problems. When applying a CSP (Common Spatial Pattern), which is an EEG extraction method, many channels cause an overfitting problem, and in addition there is difficulty using this technique for medical analysis. To overcome these problems, we suggest an optimal channel selection method using a BPSO (Binary Particle Swarm Optimization), BPSO with channel impact factor, and GA. This paper examined optimal selected channels among all channels using three optimization methods and compared the classification accuracy and the number of selected channels between BPSO, BPSO with channel impact factor, and GA by SVM (Support Vector Machine). The result showed that BPSO with channel impact factor selected 2 fewer channels and even improved accuracy by 10.17~11.34% compared with BPSO and GA.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.71-78
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• 2017

디지털 방사선영상 시스템에서 산란선은 피검사체와 엑스선의 반응에 의해 발생하는 근원적인 현상이다. 방사선 투사영상은 일차선에 의해 형성되는 감쇠정보를 영상화 하므로 산란선은 투사영상에서 노이즈로써 작용한다. 본 연구에서는 다양한 검사조건에서 발생하는 산란선을 빔 저지체(beam stopper)를 이용하여 정량화하고 동시에 반 산란 격자의 효과를 확인하였다. 또한 산란선이 영상의 품질에 미치는 영향을 확인하기 위해 산란선에 의해 저하되는 대조도 대 잡음비를 측정하였다. 본 연구를 통해 산란선은 피검사체의 두께 및 공기층(air gap)에 지배적인 경향을 가짐을 확인하였다. 또한 산란선은 영상의 대조도를 현격히 저하시킴을 정량적으로 측정하였다. 산란선을 저감하기 위해 격자를 장착함으로써 상당량의 산란선을 저감할 수 있었으나 여전히 두꺼운 피검사체에 대해 많은 양의 산란선이 남아 있음을 확인하였다. 본 연구에서는 산란선을 정량화 하는 방법론을 제시하였으며, 향후 시스템의 최적화에 중요한 역할을 할 수 있을 것으로 기대된다.

• Journal of Biosystems Engineering
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• 제42권4호
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• pp.330-338
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• 2017

Purpose: The smartphone is actively being used in many research fields, primarily in medical and diagnostic applications. However, there are cases in which smartphone-based systems have been developed for agriculture, environment, and food applications. The purpose of this review is to summarize the research cases using smartphone cameras in agriculture, environment, and food. Methods: This review introduces seventeen research cases which used smartphone cameras in agriculture, food, water, and soil applications. These were classified as systems involving "smartphone-camera-alone" and "smartphone camera with optical accessories". Results: Detecting food-borne pathogens, analyzing the quality of foods, monitoring water quality and safety, gathering information regarding plant growth or damage, identifying weeds, and measuring soil loss after rain were presented for the smartphone-camera-alone system. Measuring food and water quality and safety, phenotyping seeds, and soil classifications were presented for the smartphone camera with optical accessories. Conclusions: Smartphone cameras were applied in various areas for several purposes. The use of smartphone cameras has advantages regarding high-resolution imaging, manual or auto exposure and focus control, ease of use, portability, image storage, and most importantly, programmability. The studies discussed were achieved by sensitivity improvements of CCDs (charge-coupled devices) and CMOS (complementary metal-oxide-semiconductor) on smartphone cameras and improved computing power of the smartphone, respectively. A smartphone camera-based system can be used with ease, low cost, in near-real-time, and on-site. This review article presents the applications and potential of the smartphone and the smartphone camera used for various purposes in agriculture, environment, and food.

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.663-668
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• 2016

In single-photon-emission computed tomography (SPECT) with a pixelated semiconductor detector (PSD), not only pinhole collimators but also parallel-hole collimators are often used in preclinical nuclear-medicine imaging systems. The purpose of this study was to evaluate and compare pinhole and parallel-hole collimators in a PSD. For that purpose, we paired a PID 350 (Ajat Oy Ltd., Finland) CdTe PSD with each of the four collimators most frequently used in preclinical nuclear medicine: (1) a pinhole collimator, and (2) low-energy high-resolution (LEHR), (3) low-energy general-purpose (LEGP), and (4) low-energy high-sensitivity (LEHS) parallel-hole collimators. The sensitivity and spatial resolution of each collimator was evaluated using a point source and a hot-rod phantom. The highest sensitivity was achieved using LEHS, followed by LEGP, LEHR, and pinhole. Also, at a source-to-collimator distance of 2 cm, the spatial resolution was 1.63, 2.05, 2.79, and 3.45 mm using pinhole, LEHR, LEGP, and LEHS, respectively. The reconstructed hot-rod phantom images showed that the pinhole collimator and the LEHR parallel-hole collimator give a fine spatial resolution for preclinical SPECT with PSD. In conclusion, we successfully compared different types of collimators for a preclinical pixelated semiconductor SPECT system.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.776-780
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• 2017

To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a $^{99m}Tc$ gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

• Nuclear Medicine and Molecular Imaging
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• 제41권2호
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• pp.141-151
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• 2007

파킨슨병은 노년층에 가장 흔한 퇴행성 뇌질환 중의 하나로 진행성핵상마비, 다중계 위축, 루이체 치매 등과 같은 비전형 파킨슨병과 임상적으로 감별이 어려울 수 있다. 파킨슨병과 비전형 파킨슨병의 감별은 치료방침 결정과 예후평가뿐만 아니라 파킨슨병의 원인과 병태생리를 연구하고 새로운 치료법 개발에 있어서도 매우 중요하다. 파킨슨병과 비전형 파킨슨병과 같이 파킨슨 증후군을 유발하는 질환은 선조체내 도파민 신경의 퇴행성 변화를 흔히 동반하지만 병태생리학적으로 서로 다른 뇌피질 및 피질하 구조물에서의 신경세포 소실을 동반하고 있다. 따라서 국소 시냅스 활성도와 신경 및 시냅스의 손상, 그리고 원발병변과 기능적으로 연결된 원격부위의 기능이상 등을 대변하는 뇌포도당 대사를 F-18FDG PET으로 평가하는 것은 파킨슨 병의 감별진단과 병태생리를 평가하는데 유용하다.