• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.462-463
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• 2012

팍스시스템은 의료 영상을 디지탈화한 시스템이다. PACS데이터는 초창기 CR(Computed Radiography)의 경우 10MB내외의 데이터를 발생하였으나 의료장비의 발전으로 인해 DB(Digital Radiography)는 20MB이상의 데이터를 발생하였다. 또 CT(Computed Tomography)의 경우 0.5MB데이터를 100Slice내외의 데이터를 발생하였으나, 현재는 Cardiac/PET 등의 CT는 Multi Frame을 지원하며 300~5000Slice이상의 데이터를 발생하게 됨에 따라 네트워크에 상당한 트래픽이 발생하여 병원 진료 환경에 심각한 영향을 초래한다. 또한, 스마트 폰, 태블릿 pc등의 발전으로 인해 많은 사용자들은 실시간 또는 멀티미디어와 같은 데이터 표현 방식으로 팍스 데이터를 보길 원할 것이며, 팍스 시스템 또한 그러한 요구조건을 만족시키기 위해 발전하고 있다. 병원에서 사용하는 네트워크는 인터넷 서비스의 모토인 best effort방법을 일반적으로 사용한다. 이러한 데이터 전송방식은 진료에 직접적인 영향을 미치는 팍스 데이터의 전송에 영향을 미칠 수 있다. 특히 네트워크의 트래픽이 제한적인 환경에서 높은 대역폭을 요구하는 멀티미디어 팍스 데이터를 다수의 사용자들이 전송받기 원하면 지연시간으로 인해 원활한 진료진행을 방해 받을 수 있다. 이러한 문제를 해결하기 위해 네트워크 개발자들은 QoS라는 개념을 도입하였고, 여러 계층에서 QoS를 보장하기 위한 연구가 진행되였다. 일반적으로, 네트워크에서 QoS를 지원하기 위한 여러가지 형태의 연구들을 조사하고, 분산 시스템을 제어하기 위한 DDS 미들웨어에 대한 연구를 기반으로 병원 네트워크에서 적용 방안을 설계하고 시뮬레이션을 통해 검증함으로써 새로운 형태의 병원 네트워크를 제안하고자 한다.

• Applied Microscopy
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• v.41 no.3
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• pp.147-154
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• 2011

Backscattered electrons (BSE) are generated at the impact of the primary electron beam on the specimen. BSE imaging provides the compositional contrast to resolve chemical features of sectioned block-face. A focused ion beam (FIB) column can be combined with a field emission scanning electron microscope (FESEM) to ensure a dual (or cross)-beam system (FIB-FESEM). Due to the milling of the specimen material by 10 to 100 nm with the gallium ion beam, FIB-FESEM allows the serial block-face (SBF) imaging of plastic-embedded specimens with high z-axis resolution. After contrast inversion, BSE images are similar to transmitted electron images by transmission electron microscopy. As another means of SBF imaging, a specialized ultramirotome has been incorporated into the specimen chamber of FESEM ($3View^{(R)}$). Internal structures of plastic-embedded specimens can be serially revealed and analyzed by $3View^{(R)}$ with a large field of view to facilitate three-dimensional reconstruction. These two SBF approaches by FESEM can be employed to unravel spatial association of (sub)cellular entities for a comprehensive understanding of complex biological systems.

• The Journal of the Acoustical Society of Korea
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• v.31 no.4
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• pp.244-252
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• 2012

The purpose of the present study is to investigate the correlations between acoustic properties, such as speed of sound and normalized broadband ultrasound attenuation, and bone mineral density in femur with high fracture risk. The speed of sound and the normalized broadband ultrasound attenuation in 15 bovine femoral trabecular bone samples in vitro were measured by using a through-transmission method with two matched pairs of ultrasonic transducers with center frequencies of 0.5 and 1.0 MHz. The volumetric bone mineral density of the trabecular bone samples was measured by using micro-computed tomography. The bone mineral density exhibited strong correlations with both the speed of sound and the normalized broadband ultrasound attenuation measured by using the 0.5 and the 1.0 MHz transducers. The highest correlation was found between the bone mineral density and the normalized broadband ultrasound attenuation measured by using the 0.5 MHz ultrasonic transducers. The results suggest that the acoustic properties measured in the femur in vitro can be used as indices for the prediction of femoral bone mineral density.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.5-9
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• 2004

In this paper, we studied the OCT(Optical Coherence Tomography) system which it has been extensively studied because of having some advantages such as high resolution cross-sectional images, low cost, and small size configuration. A basic principle of OCT system is Michelson interferometer. The characteristics of light source determine the resolution and the transmission depth. As a results, the light source have a commercial SLD with a central wavelength of 1,285 nm and FWHM(Full Width at Half Maximum) of 35.3 nm. The optical delay line part is necessary to equal of the optical path length with scattered light or reflected light from sample. In order to equal the optical path length, the stage which is attached to reference mirror is moved linearly by step motor And the interferometer is configured with the Michelson interferometer using single mod fiber, the scanner can be focused of the sample by using the reference arm. Also, the 2-dimensional cross-sectional images were measured with scanning the transverse direction of the sample by using step motor. After detecting the internal signal of lateral direction at a paint of sample, scanner is moved to obtain the cross-sectional image of 2-demensional by using step motor. Photodiode has been used which has high detection sensitivity, excellent noise characteristic, and dynamic range from 800 nm to 1,700 nm. It is detected mixed small signal between noise and interference signal with high frequency After filtering and amplifying this signal, only envelope curve of interference signal is detected. And then, cross-sectional image is shown through converting this signal into digitalized signal using A／D converter. The resolution of the OCT system is about 30$\mu\textrm{m}$ which corresponds to the theoretical resolution. Also, the cross-sectional image of ping-pong ball is measured. The OCT system is configured with Michelson interferometer which has a low contrast because of reducing the power of feedback interference light. Such a problem is overcomed by using the improved inteferometer. Also, in order to obtain the cross-sectional image within a short time, it is necessary to reduce the measurement time for improving the optical delay line.

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.57-68
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• 2005

Purpose: The objective of this study was to assess attenuation correction algorithms with the $^{137}Cs$ point source for the brain positron omission tomography (PET) imaging process. Materials & Methods: Four different types of phantoms were used in this study for testing various types of the attenuation correction techniques. Transmission data of a $^{137}Cs$ point source were acquired after infusing the emission source into phantoms and then the emission data were subsequently acquired in 3D acquisition mode. Scatter corrections were performed with a background tail-fitting algorithm. Emission data were then reconstructed using iterative reconstruction method with a measured (MAC), elliptical (ELAC), segmented (SAC) and remapping (RAC) attenuation correction, respectively. Reconstructed images were then both qualitatively and quantitatively assessed. In addition, reconstructed images of a normal subject were assessed by nuclear medicine physicians. Subtracted images were also compared. Results: ELEC, SAC, and RAC provided a uniform phantom image with less noise for a cylindrical phantom. In contrast, a decrease in intensity at the central portion of the attenuation map was noticed at the result of the MAC. Reconstructed images of Jaszack and Hoffan phantoms presented better quality with RAC and SAC. The attenuation of a skull on images of the normal subject was clearly noticed and the attenuation correction without considering the attenuation of the skull resulted in artificial defects on images of the brain. Conclusion: the complicated and improved attenuation correction methods were needed to obtain the better accuracy of the quantitative brain PET images.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.314-317
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• 2002

The purpose of this study was to evaluate the clinical application of Patlak tool on GE PET workstation for quantitative analysis of dynamic PET images in cardiac patients. Three patients including coronary artery disease (CAD), myocardial infarction (MI), and angina were studied. All subjects underwent dynamic cardiac PET scan using a GE Advance scanner. After 10 min transmission scan for attenuation correction using two rotating $\^$68/Ge rod sources, three patients with cardiac disease were performed dynamic cardiac PET scan after the administration of approximately 370 MBq of FDG. The dynamic scan consisted of 36 frames with variable frame length (12${\times}$10s, 6${\times}$20s, 6${\times}$60s, 12${\times}$300s) for a total time of 70 min. Blood samples were obtained to determine the plasma substrate concentration. Region of interest of circular and rectangular shape to acquire input functions and tissue data were placed on left ventricle and myocardium. A value of 0.67 was used for lumped constant. Mean plasma substrate concentrations for three patients were 100 mg/dl (CAD), 100 mg/dl (MI), 132 mg/dl (angina), respectively. Regional MMRGlc values (mean${\pm}$SD) at lateral myocardium area for CAD, MI, and angina were 8.43${\pm}$0.24, 4.08${\pm}$0.16, and 6.15${\pm}$0.23 mg/min/100ml, respectively. Patlak tool on GE PET workstation appeared to be useful for quantitative analysis of dynamic PET images in cardiac patients, although further studies may be required for absolute quantitation.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.634-639
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• 2013

The use of medical imaging has been increased for diagnosis of cancer or vessel disease. Among the medical imaging, computed tomography (CT) is one of the popular methods, however, which should need administration of contrast medium. Therefore, we developed gold coated liposomes (GCL) as a contrast medium. To coat gold on the liposomal surface, positive charged liposomes was prepared and then negative $Au^-$ can coat on the liposomal surface by electronic interaction. The size of GCL was $154.8{\pm}9.2$ nm and surface charge was $27{\pm}3.2$ mV, respectively. The morphology of GCL was confirmed by electron microscopy (SEM) and transmission electron microscopy (TEM). The coating efficiency of gold was 18%. Chemical procedure for gold coating on liposomal surface was not toxic for cell cytotoxicity by MTT assay. Finally, we demonstrated attractive CT image for GCL. Taken together, the GCL would be useful for various vessel related disease as a contrast medium.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.90-101
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• 1997

The purpose of this study is to evaluate the diagnostic accuracy of various quantitative indices for the differentiation of benign from malignant primary soft tissue tumors by FDG-PET. A series of 32 patients with a variety of histologically or clinically confirmed benign (20) or malignant (12) soft tissue lesions were evaluated with emission whole body (5min/bed position) PET after injection of [$^{18}F$]FDG. Regional 20min transmission scan for the attenuation correction and calculation of SUV was performed in 16 patients (10 benign, 6malignant) followed by dynamic acquisition for 56min. Postinjection transmission scan for the attenuation correction and calculation of SUV was executed in the other 16 patients (10 benign, 6 malignant). The following indices were obtained. the peak and average SUV (pSUV, aSUV) of lesions, tumor-to-background ratio acquired at images of 51 min p.i. ($TBR_{51}$), tumor-to-background ratio of areas under time-activity curves ($TBR_{area}$) and the ratio between the activities of tumor ROI at 51 min p. i. and at the time which background ROI reaches maximum activity on the time-activity curves ($T_{51}/T_{max}$). The pSUV, aSUV, $TBR_{51}$, and $TBR_{area}$ in malignant lesions were significantly higher than those in benign lesions. We set the cut-off values of pSUV, aSUV, $TBR_{51},\;TBR_{area}$ and $T_{51}/T_{max}$ for the differentiation of benign and malignant lesions at 3.5, 2.8, 5.1, 4.3 and 1.55, respectively. The sensitivity, specificity and accuracy were 91.7%, 80.0%, 84.4% by pSUV and aSUV, 83.3%, 85.0%, 84.4% by $TBR_{51}$, 83.3%, 100%, 93.8% by $TBR_{area}$ and 66.7%, 70.0%, 68.8% by $T_{51}/T_{max}$. The time-activity curves did not give additional information compared to SUV or TBR. The one false negative was a case with low-grade fibrosarcoma and all four false positives were cases with inflammatory change on histology. The visual, analysis of FDG-PET also detected the metastatic lesions in malignant cases with comparable accuracy In conclusion, all pSUV, aSUV, $TBR_{51}$, and $TBR_{area}$ are useful metabolic semi-quantitative indices with good accuracy for the differentiation of benign from malignant soft-tissue lesions.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.89-97
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• 2021

Purpose: The purpose of this study is to compare and evaluate the dose change according to the gas volume variations in the rectum, which was not included in the treatment plan during radiation therapy for cervical cancer. Materials and methods: Static Intensity Modulated Radiation Therapy (S-IMRT) using a 9-field and Volumetric Modulated Arc Therapy (VMAT) using 2 full-arcs were established with treatment planning system on Computed Tomography images of a human phantom. Random gas parameters were included in the Planning Target Volume(PTV) with a maximum change of 2.0 cm in increments of 0.5 cm. Then, the Conformity Index (CI), Homogeneity Index (HI) and PTV D_max for the target volume were calculated, and the minimum dose (D_min), mean dose (D_mean) and Maximum Dose (D_max) were calculated and compared for OAR(organs at risk). For statistical analysis, T-test was performed to obtain a p-value, where the significance level was set to 0.05. Result: The HI coefficients of determination(R²) of S-IMRT and VMAT were 0.9423 and 0.8223, respectively, indicating a relatively clear correlation, and PTV D_max was found to increase up to 2.8% as the volume of a given gas parameter increased. In case of OAR evaluation, the dose in the bladder did not change with gas volume while a significant dose difference of more than D_mean 700 cGy was confirmed in rectum using both treatment plans at gas volumes of 1.0 cm or more. In all values except for D_mean of bladder, p-value was less than 0.05, confirming a statistically significant difference. Conclusion: In the case of gas generation not considered in the reference treatment plan, as the amount of gas increased, the dose difference at PTV and the dose delivered to the rectum increased. Therefore, during radiation therapy, it is necessary to make efforts to minimize the dose transmission error caused by a large amount of gas volumes in the rectum. Further studies will be necessary to evaluate dose transmission by not only varying the gas volume but also where the gas was located in the treatment field.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.30-41
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• 2007

Purpose: Bone metastasis in breast cancer patients are usually assessed by conventional Tc-99m methylene diphosphonate whole-body bone scan, which has a high sensitivity but a poor specificity. However, positron emission tomography with $^{18}F-2-deoxyglucose$ (FDG-PET) can offer superior spatial resolution and improved specificity. FDG-PET/CT can offer more information to assess bone metastasis than PET alone, by giving a anatomical information of non-enhanced CT image. We attempted to evaluate the usefulness of FDG-PET/CT for detecting bone metastasis in breast cancer and to compare FDG-PET/CT results with bone scan findings. Materials and Methods: The study group comprised 157 women patients (range: $28{\sim}78$ years old, $mean{\pm}SD=49.5{\pm}8.5$) with biopsy-proven breast cancer who underwent bone scan and FDG-PET/CT within 1 week interval. The final diagnosis of bone metastasis was established by histopathological findings, radiological correlation, or clinical follow-up. Bone scan was acquired over 4 hours after administration of 740 MBq Tc-99m MDP. Bone scan image was interpreted as normal, low, intermediate or high probability for osseous metastasis. FDG PET/CT was performed after 6 hours fasting. 370 MBq F-18 FDG was administered intravenously 1 hour before imaging. PET data was obtained by 3D mode and CT data, used as transmission correction database, was acquired during shallow respiration. PET images were evaluated by visual interpretation, and quantification of FDG accumulation in bone lesion was performed by maximal SUV(SUVmax) and relative SUV(SUVrel). Results: Six patients(4.4%) showed metastatic bone lesions. Four(66.6%) of 6 patients with osseous metastasis was detected by bone scan and all 6 patients(100%) were detected by PET/CT. A total of 135 bone lesions found on either FDG-PET or bone scan were consist of 108 osseous metastatic lesion and 27 benign bone lesions. Osseous metastatic lesion had higher SUVmax and SUVrel compared to benign bone lesion($4.79{\pm}3.32$ vs $1.45{\pm}0.44$, p=0.000, $3.08{\pm}2.85$ vs $0.30{\pm}0.43$, p=0.000). Among 108 osseous metastatic lesions, 76 lesions showed as abnormal uptake on bone scan, and 76 lesions also showed as increased FDG uptake on PET/CT scan. There was good agreement between FDG uptake and abnormal bone scan finding (Kendall tau-b : 0.689, p=0.000). Lesion showed increased bone tracer uptake had higher SUVmax and SUVrel compared to lesion showed no abnormal bone scan finding ($6.03{\pm}3.12$ vs $1.09{\pm}1.49$, p=0.000, $4.76{\pm}3.31$ vs $1.29{\pm}0.92$, p=0.000). The order of frequency of osseous metastatic site was vertebra, pelvis, rib, skull, sternum, scapula, femur, clavicle, and humerus. Metastatic lesion on skull had highest SUVmax and metastatic lesion on rib had highest SUVrel. Osteosclerotic metastatic lesion had lowest SUVmax and SUVrel. Conclusion: These results suggest that FDG-PET/CT is more sensitive to detect breast cancer patients with osseous metastasis. CT scan must be reviewed cautiously skeleton with bone window, because osteosclerotic metastatic lesion did not showed abnormal FDG accumulation frequently.