• 대한방사선기술학회지:방사선기술과학
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• 제33권1호
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• pp.45-50
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• 2010

본 연구는 T2고속스핀에코 3.0T 자기공명영상에서 지방조직 소거기법인 SPAIR와 STIR기법의 임상적 유용성에 관한 비교연구를 시행하였다. SPAIR와 STIR 프로토콜을 사용하여 뇌의 축방향 영상(20개), 요추의 시상단면영상(20개), 고관절의 관상단면영상(17개), 무릎관절의 축방향 영상(25개)을 획득하였다. 검사부위별로 지방억제기법의 지방소거능력과 화질을 파악하기위해 지방조직의 신호강도와 불균일성을 측정하였다. 지방조직에서 불균일치는 측정된 지방 신호의 평균치(mean)에 대한 표준편차(SD)로서 그 산출은 SD/mean으로 계산하였다. 수집된 자료는 SPSS(Statistical Package for the Social Science) WIN 13.0 프로그램을 이용하여 분석한 결과 다음과 같은 결론을 얻었다. 첫째, 뇌 검사는 SPAIR가 STIR보다 지방억제능력과 화질면에서 우수한 결과를 나타냈으며, 둘째, 요추, 고관절, 무릎관절 검사는 지방의 신호억제능력은 STIR가 우수하고, 화질면에서는 SPAIR가 우수한 결과를 나타냈다.

• Investigative Magnetic Resonance Imaging
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• 제19권3호
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• pp.162-167
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• 2015

Purpose: To evaluate the usefulness of quantitative analysis of the facial nerve using contrast-enhanced three-dimensional (CE 3D) fluid-attenuated inversion recovery-volume isotopic turbo spin echo acquisition (FLAIR-VISTA) for the diagnosis of Bell's palsy in pediatric patients. Materials and Methods: Twelve patients (24 nerves) with unilateral acute facial nerve palsy underwent MRI from March 2014 through March 2015. The unaffected sides were included as a control group. First, for quantitative analysis, the signal intensity (SI) and relative SI (RSI) for canalicular, labyrinthine, geniculate ganglion, tympanic, and mastoid segments of the facial nerve on CE 3D FLAIR images were measured using regions of interest (ROI). Second, CE 3D FLAIR and CE T1-SE images were analyzed to compare their diagnostic performance by visual assessment (VA). The sensitivity, specificity, and accuracy of RSI measurement and VA were compared. Results: The absolute SI of canalicular and mastoid segments and the sum of the five mean SI (total SI) were higher in the palsy group than in the control group, but with no significant differences. The RSI of the canalicular segment and the total SI were significantly correlated with the symptomatic side (P = 0.028 and 0.015). In 11/12 (91.6%) patients, the RSI of total SI resulted in accurate detection of the affected side. The sensitivity, specificity, and accuracy for detecting Bell's palsy were higher with RSI measurement than with VA of CE 3D FLAIR images, while those with VA of CE T1-SE images were higher than those with VA of CE 3D FLAIR images. Conclusion: Quantitative analysis of the facial nerve using CE 3D FLAIR imaging can be useful for increasing the diagnostic performance in children with Bell's palsy when difficult to diagnose using VA alone. With regard to VA, the diagnostic performance of CE T1-SE imaging is superior to that of CE 3D FLAIR imaging in children. Further studies including larger populations are necessary.

• Korean Journal of Radiology
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• 제23권7호
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• pp.720-731
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• 2022

Objective: We aimed to develop and test a deep learning algorithm (DLA) for fully automated measurement of the volume and signal intensity (SI) of the liver and spleen using gadoxetic acid-enhanced hepatobiliary phase (HBP)-magnetic resonance imaging (MRI) and to evaluate the clinical utility of DLA-assisted assessment of functional liver capacity. Materials and Methods: The DLA was developed using HBP-MRI data from 1014 patients. Using an independent test dataset (110 internal and 90 external MRI data), the segmentation performance of the DLA was measured using the Dice similarity score (DSS), and the agreement between the DLA and the ground truth for the volume and SI measurements was assessed with a Bland-Altman 95% limit of agreement (LOA). In 276 separate patients (male:female, 191:85; mean age ± standard deviation, 40 ± 15 years) who underwent hepatic resection, we evaluated the correlations between various DLA-based MRI indices, including liver volume normalized by body surface area (LV_BSA), liver-to-spleen SI ratio (LSSR), MRI parameter-adjusted LSSR (aLSSR), LSSR × LV_BSA, and aLSSR × LV_BSA, and the indocyanine green retention rate at 15 minutes (ICG-R15), and determined the diagnostic performance of the DLA-based MRI indices to detect ICG-R15 ≥ 20%. Results: In the test dataset, the mean DSS was 0.977 for liver segmentation and 0.946 for spleen segmentation. The Bland-Altman 95% LOAs were 0.08% ± 3.70% for the liver volume, 0.20% ± 7.89% for the spleen volume, -0.02% ± 1.28% for the liver SI, and -0.01% ± 1.70% for the spleen SI. Among DLA-based MRI indices, aLSSR × LV_BSA showed the strongest correlation with ICG-R15 (r = -0.54, p < 0.001), with area under receiver operating characteristic curve of 0.932 (95% confidence interval, 0.895-0.959) to diagnose ICG-R15 ≥ 20%. Conclusion: Our DLA can accurately measure the volume and SI of the liver and spleen and may be useful for assessing functional liver capacity using gadoxetic acid-enhanced HBP-MRI.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1061-1070
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• 2003

A triple flame in a mixing layer was studied experimentally with concentration gradient and mean velocity by using a multi-slot burner, which can stabilize the lift-off flame. Flame stabilization condition, lift-off heights, and some other characteristics were examined for methane and propane flame within a range of very low concentration gradient. Pitot-tube and LDV(Laser Doppler Velocimetry) were used for velocity. Mass spectroscopy and Rayleigh scattering signal were used for concentration gradients. Thermo-couples and SiC TFP(Thin Filament Pyrometer) were used for temperature. It was found that minimum values of the lift-off heights exist at a certain concentration gradient for constant mean velocity and this means that the propagation velocity has a maximum value. The scales of flame to the burner nozzle and intensity variation of the diffusion flame were suspected as the cause.

• 센서학회지
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• 제13권2호
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• pp.85-89
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• 2004

This paper represents the development of high sensitivity photo-sensor for the fluorescence detection in the integrated biological analysis system. The finger-type PIN photodiodes were fabricated as the photo-sensor, and had a high sensitivity ($I_{light}/I_{dark}$ = 8720). The interference filter consisted of $TiO_{2}$ and $SiO_{2}$ was directly deposited on the photodiodes. Deposited filter with 95.5% reflection under 532 nm and 98% transmission over 580 nm exceedingly decreased the magnitude of background signal in the detection. The PDMS micro-fluidic channels are bonded on the photodiode by $O_{2}$ plasma treatment. The detection current was proportional to two primary parameters (light intensity, concentration), and the on-chip detection system could detect fluorescence signals down to 100 nM concentration (LOD = Limit of detection of rhodamine).

• 한국자기공명학회논문지
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• 제6권2호
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• pp.84-88
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• 2002

Dating and dosimetry using electron spin resonance (ESR) in 20th Century developed at both Yamaguchi University and Osaka University have been reviewed with emphasis on new prospects and strategies in 21th century. Natural radiation have been generating radicals that accumulated in archaeological and geological materials. ESR detects these radicals and the ESR signal intensity is proportional to the radiation dose and therefore the age. The assessment of the total dose of natural radiation and the annual dose rate give their ESR ages. The ESR dating of stalactites and stalagmites ant Akiyoshi cave in Yamaguchi prefecture in 1975 was extended to anthropological dating using bones and tooth enamel excavated in Greek Petralona cave. Fossils of shells and corals gave the ages of marine terraces and sea-level changes. Quartz grains gave the ages of geothermal alteration and fault movements. Future ESR dating of ices at outer planets anf their satellite are also investigated as basic studies for ices od $H_2O,\;CO_2,\;SO_2$ as well as terrestrial hydrates in laboratory. Atomic bomb radiation dosimetry at Hiroshima and Nagasaki using ESR lead to the dosimetry of personnel, Chemobyl and JCO criticality accidents. Monitoring of radiation dose with sensitive materials with tissue equivalence are being developed. finally a new scanning ESR imaging apparatus (a near field microwave microscope) developed in our laboratory gave ESR images of Radicals from fossils to Si-CVD and diamond films as summarized in my book in 2002.

• 대한의용생체공학회:의공학회지
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• 제16권2호
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• pp.209-216
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• 1995

Recently, a new tailored RF gradient echo (TRFGE) sequence was reported. This technique not only enhances the magnetic susceptibility effect but also allows us to measure local changes in brain oxygenation. In this study, a phantom and cat brain experiments were performed on a 4.7 Tesla BIQSPEC (BRUKER) instrument with a 26 cm gradient system. We have demonstrated that the signal intensity (SI) of the TRFGE sequence varies according to the concentration of susceptibility contrast agent. Three capillary tubes with different concentrations of Gd-DTPA (0.01, 0.05, 0.1 mMOI/l) were placed at the middle of a cylindrical water phantom. Using both TRFGE and conventional gradient echo (CGE) sequences, phantom images of the slices which contain all three tubes were obtained. For the animal experiment, cats were anesthetized and ventilated using halotane (0.5%) and a $N_2O/ O_2$ mixture (2:1), and blood pressure and heart rate were monitored and kept normal. For the observation of tue first pass of Gd- DTPA, imaging was started at t = 0. At t = 8 ~ 12s, 0.2 mMol/Kg Gd-DTPA was manually injected in the femoral vein. The imaging parameters were TRITE = 25/10 msec, flip angle = $30^{\circ}$, FOV = 10cm, image matrix size = $128{\times}128$ with 64 phase encodings and the image data acquisition window was 10 msec. SI-time curves were then obtained from a series of 30 images which were collected at 2 sec intervals using both CGE and TRFGE pulse sequences before, during, and following the contrast injection.

• 대한골관절종양학회지
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• 제5권1호
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• pp.29-34
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• 1999

Chondroblastoma is an uncommon neoplasm in bone, occurring at the epiphysis or apophysis of growing long bones and is known to have a recurrence rate of around 10% after surgical treatment. We reviewed 14 patients of pathologically proven chondroblastoma, who were surgically treated, from December 1987 to August 1997. The location of tumors was proximal femur in 4 cases, distal femur in 4 cases, proximal tibia in 2 cases, patella in 1 case, proximal humerus in 1 case and calcaneus in 1 case. The most common complaint was pain. In all nine cases in which MRI was performed, the MR imaging showed a lobulated low signal intensity(SI) rim. Low SI foci within the tumor were present in 4 of 9 cases and corresponded to calcification seen on radiographs or CT. Bone marrow edema was also present in 4 of 9 cases on MR imaging. The average duration of follow-up was 2 years, 5 months, ranging from 1 year to 7 years, 2 months. Twelve patients were treated by curettage and autogenous bone graft, one by curettage only, and one by curettage and bone cementing. Two cases which showed local recurrence were treated with curettage and bone graft. Two recurred cases had the presence of bone marrow edema on MR imaging. The presence or absence of bone marrow edema may be a useful indication of tumor activity, although further study will be required.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• 전자공학회논문지
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• 제49권9호
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• pp.322-327
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• 2012

마주보는 2개의 병렬전극을 이용한 스캔 방식의 디지털 X-ray 영상 센서는 많은 발전을 해왔으며 상업용으로 널리 이용되고 있다. 본 연구에서는 PDP(plasma display panel) 제조 공정에서 사용되고 있는 글라스 재질에 silver paste 전극을 이용하여 드리프트 전극과 픽셀 전극이 있는 챔버를 형성하고 챔버내에 X-ray와 반응하는 Xe 가스를 주입하여 스캔 방식의 1D X-ray 영상 센서를 제작하였다. 드리프트 전극의 바이어스 전압 크기에 따른 싱글 픽셀의 X-ray 신호 크기를 평가하였으며 납(Pb)을 이용하여 싱글 픽셀을 차폐하였을 경우와 차폐하지 않았을 때의 싱글 픽셀 신호 특성을 조사하였다. X-ray 흡수율(4%)은 소다 라임(soda lime, 1.1mm) 글라스에서 가장 낮았으며 센서에서 검출되는 전기적 신호는 드리프트 전극에 인가하는 전압이 클수록 증가하였다. 그리고 자체 제작한 DAS(data acquisition system) 및 센서 스캐닝 시스템을 이용하여 디지털 영상을 구현하였다.