• 한국자기학회지
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• 제26권5호
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• pp.168-172
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• 2016

MRI 검사실의 최적환경을 목적으로 검사실 및 모니터의 휘도와 조도를 측정하였다. 대학병원(n = 6)의 MRI(n = 10)에서 휘도와 조도를 Unfors Xi Light Probe(Unfors Instruments AB, Billdal, Sweden)를 이용하여 측정하였다. 휘도는 black level과 white level을 조도는 모니터의 측면의 중앙에서 3회 반복하여 평균과 표준편차를 구하여 t-test를 이용하여 유의성 검정의 통계적 처리를 하였다. 모니터 휘도는 black level에서 평균 $1.78cd/m^2$, 표준편차 $0.85cd/m^2$이었고, white level에서는 평균 $43.58cd/m^2$, 표준편차 $13.19cd/m^2$로 측정되었다. MRI 검사실 조도는 최저값 30.5 lux, 최대값 601.3 lux, 평균 177.86 lux로 측정되었고, 휘도와 조도는 통계학적으로 유의한 차이가 있다(p < .05). MRI 모니터 및 검사실 휘도와 조도의 권고 기준을 참고하여 최적인 환경을 조성하도록 한다.

• Investigative Magnetic Resonance Imaging
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• 제23권3호
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• pp.202-209
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• 2019

Purpose: To investigate the temperature-based differences of cortical bone ultrashort echo time MRI (UTE-MRI) biomarkers between body and room temperatures. Investigations of ex vivo UTE-MRI techniques were performed mostly at room temperature however, it is noted that the MRI properties of cortical bone may differ in vivo due to the higher temperature which exists as a condition in the live body. Materials and Methods: Cortical bone specimens from fourteen donors ($63{\pm}21$ years old, 6 females and 8 males) were scanned on a 3T clinical scanner at body and room temperatures to perform T1, $T2^*$, inversion recovery UTE (IR-UTE) $T2^*$ measurements, and two-pool magnetization transfer (MT) modeling. Results: Single-component $T2^*$, $IR-T2^*$, short and long component $T2^*s$ from bi-component analysis, and T1 showed significantly higher values while the noted macromolecular fraction (MMF) from MT modeling showed significantly lower values at body temperature, as compared with room temperature. However, it is noted that the short component fraction (Frac1) showed higher values at body temperature. Conclusion: This study highlights the need for careful consideration of the temperature effects on MRI measurements, before extending a conclusion from ex vivo studies on cortical bone specimens to clinical in vivo studies. It is noted that the increased relaxation times at higher temperature was most likely due to an increased molecular motion. The T1 increase for the studied human bone specimens was noted as being significantly higher than the previously reported values for bovine cortical bone. The prevailing discipline notes that the increased relaxation times of the bound water likely resulted in a lower signal loss during data acquisition, which led to the incidence of a higher Frac1 at body temperature.

• Journal of Magnetics
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• 제20권3호
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• pp.295-301
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• 2015

We evaluated certain issues related to magnetic resonance imaging (MRI) coupled with the use of active 2.5 GHz radio frequency identification (RFID) tags for patient identification using low field (0.3 T) MRI and computed tomography (CT) scans. We also investigated the performance of the RFID reader located outside the MRI room by considering several factors. A total of ten active RFID tags were exposed to several MRI sequences and X-rays of CT scan. We found that only card type active RFID tags are suitable for patient identification purpose in MRI environment and both wristbands as well as card tags were suitable for the same in CT environment. Severe artifacts were found in the captured MRI and CT images when the area of the imaging was in proximity to the tags. No external factors affected the performance of active RFID reader stationed outside the MRI scan room.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.121-124
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• 2001

The research results on the superconducting magnet for whole body MRI are presented. The magnet consists of main coil with 6 solenoid coils, shielding coil with 2 solenoid coils and 6 sets of cryogenic shim coil. The ferromagnetic shim assembly is installed on the inside wall of the room temperature bore for shimming inhomogeneous field components generated due to manufacturing tolerances, installation misalignments and external ferromagnetic materials near the magnet. Also, the magnet is enclosed with the horizontal type cryostat with 80cm room temperature bore to keep the magnet under the operating temperature. The magnetic field distributions within the imaging volume were measured by the NMR field mapping system. Through the test, the central field of magnet was 1.5 Tesla and the field homogeneity of 9.3 ppm has been obtained on 40cm DSV(the diameter of spherical volume) and using this magnet, comparatively good images for human body, fruits and water phantoms have been achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.153-155
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• 1995

We fabricated superconducting magnet for MRI and tested it using automatic field mapping system. This magnet has 20cm diameter of room temperature bore for the sample access. In this paper, the fabrication of MRI magnet system and the test results of field homogeneity are described.

• 한국콘텐츠학회논문지
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• 제16권11호
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• pp.699-706
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• 2016

본 연구는 MRI 검사로 인하여 방사선사가 노출되는 소음의 양을 평가하여 소음저감 시설의 필요성과 제도 마련을 제안하고자 하였다. 소음측정은 대전광역시 S 종합병원의 1.5 Tesla MRI 장비(7개 검사)와 3.0 Tesla MRI 장비(16개 검사)를 대상으로 하였고, 소음측정기는 SC-804를 사용하였다. 소음측정 거리는 MRI 검사실 방음문에서 검사자의 업무 위치까지 100cm 이며, 측정 높이는 업무 시 검사자의 귀 높이 100cm 이다. 검사별 소음측정은 각 검사의 시퀀스(Sequence)마다 발생되는 소음 수치를 관측하여 20초마다 기록하였고 검사별 3회씩 측정하여 평균값을 제시하였다. 연구결과 방사선사가 노출되는 소음의 최댓값은 73.3 dB(A)로 3.0 Tesla 장비에서 시행한 MRCP 검사, 검사별 평균소음의 최댓값은 66.9(3.1) dB(A)로 역시 3.0 Tesla 장비에서 시행한 Myelogram 검사이다. 장비별 평균소음은 3.0 Tesla 장비가 61.9(4.1) dB(A), 1.5 Tesla 장비가 52.0(3.1) dB(A)로 3.0 Tesla MRI 장비가 약 10 dB(A) 정도 높았다(p<0.001). 방사선사가 노출되는 소음의 양은 청력에 영향을 미치는 수준은 아니지만 비청력적영향이 발생할 수 있는 수준이다. 소음을 저감하기 위해 MRI 조정실 후면에 커튼을 설치하여 반사음을 제거할 수 있지만, 제도 마련이 선행되어야 할 것이다.

• 디지털융복합연구
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• 제11권12호
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• pp.665-672
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• 2013

영상의학과에는 다양한 질병을 가진 환자들이 검사를 받는 곳으로 병원감염의 교차 오염이 될 가능성이 큰 부서이다. 특히 자기공명영상(MRI)검사는 다른 검사에 비해 검사시간이 오래 걸려 교차오염에 더욱더 노출이 될 수 있다. 이에 본 연구는 MRI검사장비의 소독실태를 파악하고, 환자와 접촉이 가장 많은 Head coil, 환자 고정용 Block, 밀폐된 공간인 Bore에서의 세균분포도를 파악 하였다. MRI 검사장비의 소독실태는 MRI실 근무자 150명을 대상으로 설문을 실시하였으며, 세균분포의 파악은 10 곳의 의료기관에서 측정하였다. MRI 장비의 세균 분포도결과 Staphylococcus, 등의 다양한 세균들이 발견되었다. MRI실 소독실태 파악결과 Head coil, Block, Bore의 소독은 잘 시행되는 것으로 나타났으며, 소독의 시기는 아침에 1회 소독을 가장 많이 시행 하는 것으로 나타났다. 또한 감염관리자에 따른 소독의 유, 무와 소독의 시기에서는 MRI실 검사자가 감염관리 할 때 잘 시행되는 것으로 나타났다. 환자를 검사한 후 교차오염을 방지하기 위하여 바로 적절한 소독제로 소독을 실시하여 교차오염을 방지하여야 할 것이다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2014년도 춘계 종합학술대회 논문집
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• pp.325-326
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• 2014

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.22-25
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• 2001

The research results on the superconducting magnet for whole body MRI are presented. The magnet consists of main coil with 6 solenoid coils, shielding coil with 2 solenoid coils and 6 sets of cryogenic shim coil. The ferromagnetic shim assembly is installed on the inside wall of the room temperature bore for shimming inhomogeneous field components generated due to manufacturing tolerances, installation misalignments and external ferromagnetic materials near the magnet. Also, the magnet is enclosed with the horizontal type cryostat with 80cm room temperature bore to keep the magnet under the operating temperature. The magnetic field distributions within the imaging volume were measured by the NMR field mapping system. Through the test, the central field of magnet was 1.5 Tesla and the field homogeneity of 9.3 ppm has been obtained on 40cm DSV(the diameter of spherical volume) and using this magnet, comparatively good images for human body, fruits and water phantoms have been achieved.

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.223-230
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• 2005

This paper presents a new approach to investigate spatial correlation between independent components of brain alpha activity in functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). To avoid potential problems of simultaneous fMRI and EEG acquisitions in imaging pure alpha activity, data from each modality were acquired separately under a 'three conditions' setup where one of the conditions involved closing eyes and relaxing, thus making it conducive to generation of alpha activity. The other two conditions -- eyes open in a lighted room or engaged in a mental arithmetic task, were designed to attenuate alpha activity. Using a Mixture Density Independent Component Analysis (MD-ICA) that incorporates flexible non-linearity functions into the conventional ICA framework, we could identify the spatiotemporal components of fMRI activations and EEG activities associated with the alpha rhythm. Then, the sources of the individual EEG alpha activity component were localized by a Maximum Entropy (ME) method that is specially designed to find the most probable dipole distribution minimizing the localization error in sense of LMSE. The resulting active dipoles were spatially transformed to 3D MRls of the subject and compared to fMRI alpha activity maps. A good spatial correlation was found in the spatial distribution of alpha sources derived independently from fMRI and EEG, suggesting the proposed method can localize the cortical areas responsible for generating alpha activity successfully in either fMRI or EEG. Finally a functional connectivity analysis was applied to show that alpha activity sources of both modalities were also functionally connected to each other, implying that they are involved in performing a common function: 'the generation of alpha rhythms'.