• Journal of the Korean Society of Radiology
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• v.9 no.3
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• pp.139-145
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• 2015

When examining a patient using SPECT, gamma rays emitted from the body decrease or scatter. And when they reach the detector they spread in accordance with physical characteristics and geometric shapes of the scanner, quantitative analysis was difficult. For exact quantitative analysis of gamma rays emitted from the body, so that they must be considered to correction about PVE(partial volume effect). In this paper, sinogram filter was implemented to solve comprehensive PVE of SPECT. According to the results in which implemented filter was applied, partial volume effect caused by SPECT was removed. To compare proposed method and conventional method, PSNR(Peak Signal to Noise Ratio) was executed. As a result, proposed method was indicated as 7dB, conventional method was indicated as 14db respectively. dB(decibel) level of the proposed methods is lower, since the MSE(mean square error) becomes greater because scattered ray was removed, PSNR value is low. Therefore, by applying the proposed method for removing the PVE of SPECT imaging method, the image quality is improved.

• 대한핵의학회:학술대회논문집
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• 1995.05a
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• pp.224-224
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• 1995

• Progress in Medical Physics
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• v.14 no.3
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• pp.203-210
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• 2003

PET (positron emission tomography) permits the investigation of physiological and biochemical processes in vivo. The accuracy of quantifying PET data is affected by its finite spatial resolution, which causes partial volume effects. In this study, we developed a method for partial volume correction using Hoffman phantom PET and MR data, and applied various FWHM (full width at half maximum) levels. We also applied this method to PET images of normal controls and tested for the possibility of clinical application. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices. The gray matter and white matter regions were then segmented into binary images. Each binary image was convolved by 4, 8, 12, 16 mm FWHM levels. These convolved images of gray and white matter were merged corresponding to the same level of FWHM. The original PET images were then divided by the convolved binary images voxel-by-voxel. These corrected PET images were multiplied by binary images. The corrected PET images were evaluated by analyzing regions of interests, which were drawn on the gray and white matter regions of the original MR image slices. We calculated the ratio of white to gray matter. We also applied this method to the PET images of normal controls. On analyzing the corrected PET images of Hoffman phantom, the ratios of the corrected images increased more than that of the uncorrected images. With the normal controls, the ratio of the corrected images increased more than that of the uncorrected images. The ratio increase of the corrected PET images was lower than that of the corrected phantom PET images. In conclusion, the method developed for partial volume correction in PET data may be clinically applied, although further study may be required for optimal correction.

• Childhood Kidney Diseases
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• v.11 no.2
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• pp.272-279
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• 2007

Purpose : We tried to find out the clinical parameters which predict the outcome of treatment in children with enuresis. Methods : Enuresis patients who visited our hospital during 2003-2007 were included. Parameters such as age, gender, height, weight, minimal voided volume, maximal voided volume, maximum functional bladder capacity, frequency of voiding, urine S,G. before and after sleep were measured and an enuresis diary was also recorded. The reduction in wetting frequencies were classified into three groups; none(<50%), partial(50-90%) and complete(90%) response groups. We also compared the 'initial responders' who showed improvement(${\ge}50%$) during the 2 weeks of evaluation and behavioral therapy to the 'initial non-responders'. Results : Parameters mentioned above showed no significant relation to the treatment out-come. The response rate during the 2 weeks of the evaluation period was 32%(49/151) [complete in 1.3% (2/151), partial in 29.6% (47/151)]. Two-months' treatment responses were complete in 14(40%), partial in 19(54.3%) and none in 2(5.9%) responders(n=35), while they were 10(13.5%), 46(62.2%) and 18(24.3%), respectively in the non-responders(n=73) (P<0.05). Conclusion : We suggest that initial 'responsiveness' can be used as a predictor for good treatment outcome in patients with enuresis.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.18-24
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• 2013

Purpose: Myocardial perfusion SPECT using $^{201}Tl$ is an important method for viability of left ventricle and quantitative evaluation of cardiac function and now various reconstruction methods are used to improve the image quality. But in case of small sized heart, you should always be careful because of the Partial Volume Effect which may cause errors of quantitative indices at the reconstruction step. So, In this study, we compared those quantitative indices of left ventricle according to the reconstruction method of myocardial perfusion SPECT with the Echocardiography and verified the degree of the differences between them. Materials and Methods: Based on ESV 30 mL of Echocardiography, we divided 278 patients (male;98, female;188, Mean age;$65.5{\pm}11.1$) who visited the Asan medical center from February to September, 2012 into two categories; below the criteria to small sized heart, otherwise, normal or large sized heart. Filtered and output each case, we applied the method of FBP and OSEM to each of them, and calculated EDV, ESV and LVEF, and we conducted statistical processing through Repeated Measures ANOVA with indices that measured in Echocardiography. Results: In case of men and women, there were no significant difference in EDV between FBP and OSEM (p=0.053, p=0.098), but in case of Echocardiography, there were meaningful differences (p<0.001). The change of ESV especially women in small sized heard, significant differences has occurred among FBP, OSEM and Echocardiography. Also, in LVEF, there were no difference in men and women who have normal sized heart among FBP, OSEM and Echocardiography (p=0.375, p=0.969), but the women with small sized heart have showed significant differences (p<0.001). Conclusion: The change in quantitative indices of left ventricle between Nuclear cardiology image reconstruction, no difference has occurred in the patients with normal sized heart but based on ESV, under 30 mL of small sized heart, especially in female, there were significant differences in FBP, OSEM and Echocardiography. We found out that overestimated LVEF caused by PVE can be reduced in average by applying OSEM to all kinds of gamma camera, which are used in analyzing the differences.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.65-75
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• 2016

Purpose : By analyzing seroma volume changes in the patients who underwent Partial breast radiation therapy after breast conserving surgery, we try to contribute to the improvement of radiotherapy effect. Materials and Methods : Enrolled 20 patients who underwent partial breast radiation therapy by ViewRay MRIdian System were subject. After seeking for the size of the removed sample in the patients during surgery and obtained seroma volume changes on a weekly basis. On the Basis of acquired volume, it was compared with age, term from start of the first treatment after surgery, BMI (body mass index) and the extracted sample size during surgery. And using the ViewRay MRIdian RTP System, the figure was analyzed by PTV(=seroma volume + margin) to obtain a specific volume of the Partial breast radiation therapy. Results : The changes of seroma volume from MR simulation to the first treatment (a week) is 0~5% in 8, 5~10% in 3, 10 to 15% in 2, and 20% or more in 5 people. Two patients(A, B patient) among subjects showed the biggest change. The A patient's 100% of the prescribed dose volume is 213.08 cc, PTV is 181.93 cc, seroma volume is 15.3 cc in initial plan. However, while seroma volume decreased 65.36% to 5.3 cc, 100% of the prescribed dose volume was reduced to 3.4% to 102.43 cc and PTV also did 43.6% to 102.54 cc. In the case of the B patient, seroma volume decreased 42.57% from 20.2 cc to 11.6 cc. Because of that, 100% of the prescribed dose volume decreased 8.1% and PTV also did to 40%. Conclusion : As the period between the first therapy and surgery is shorter, the patient is elder and the size of sample is smaller than 100 cc, the change grow bigger. It is desirable to establish an adaptive plan according to each patient's changes of seroma volume through continuous observation. Because partial breast patients is more sensitive than WBRT patients about dose conformity in accordance with the volume change.

• Journal of Biomedical Engineering Research
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• v.37 no.2
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• pp.84-89
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• 2016

In this study, we proposed ameliorated method for region of interest (ROI) study to improve its accuracy using partial volume effect (PVE). PVE which arose in volumetric images when more than one tissue type occur in a voxel, could be used to reduce an amount of gray matter and cerebrospinal fluid within ROI of diffusion tensor image (DTI). In order to define ROIs, individual b0 image was spatially aligned to the JHU DTI-based atlas using linear and non-linear registration (http://cmrm.med.jhmi.edu/). Fractional anisotropy (FA) and mean diffusivity (MD) maps were estimated by fitting diffusion tensor model to each image voxel, and their mean values were computed within each ROI with PVE threshold. Participants of this study consisted of 20 healthy controls, 27 Alzheimer's disease and 27 normal-pressure hydrocephalus patients. The result showed that the mean FA and MD of each ROI were increased and decreased respectively, but standard deviation was significantly decreased when PVE was applied. In conclusion, the proposed method suggested that PVE was indispensable to improve an accuracy of DTI ROI study.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.121-124
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• 2012

오늘날 급속한 산업사회 및 환경변화로 인하여 불특정 다수인들이 생활하는 공간들이 고층화 및 대형화가 가속되면서 여러 가지 문제점들이 나타나고 있으며, 그중 특히 소방안전에 있어서 현실을 만족하지 못하는 부분이 적지 않다. 이러한 문제점들을 보완하기 위하여 소방장비에 적용되어지는 소방펌프의 문제점들을 보완하고 이를 적극 활용하여 새로운 소화체계의 개선과 장비 운영의 효율화를 기하고자 하며, 앞서 연구 개발된 회전용적형 펌프에 기동성과 다양성을 접목하여 기존의 소방시스템에 적극 활용하고자 한다. 그간 법적인 문제로 인하여 원심펌프 이외의 펌프를 소방장비에 적용하기에는 현실적으로 적지 않은 어려움이 있었다. 전술한 문제점을 보완하여 기동성과 접근성을 도출하여 초기화재에 보다 효과적으로 대응하는 소방장비의 접목 가능성을 제시하고자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.3
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• pp.20-28
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• 2007

The easiest way to see the phenomena of compressor surge is to show the static and dynamic operation characteristic on the map. Its operation zone will be restricted by the surge limit and, static and transient process must have some margin for it. Effect of rotor moment of inertia, air/gas volumes and heat transfer are factors to cause the transition from the static line. In case a large volume such as heat exchanger exists in the system it will exert a substantial influence to dynamic characteristics. In the present paper, influence of air volume bled from the compressor exit on transient process is investigated with an example of an auxiliary power unit micro-turbine engine. Turbine mass, pressure ratio, rotation speed, power and moment are calculated based on mass and work conservation. Result from the present study can give guidance to design the control system. A computer program is developed to calculate the dynamic process using the MathCAD commercial software.

• Journal of Chest Surgery
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• v.35 no.9
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• pp.664-667
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• 2002

Extracorporeal membrane oxygenation(ECMO) provides stable oxygenation to prevent elevation of pulmonary vascular resistance and bypasses a significant part of cardiac output to the pulmonary vascular bed to reduce pulmonary perfusion pressure. In addition, ECMO prevents right heart failure and low cardiac output by means of ventricular assist and reduction in volume load to right ventricle. As a result, ECMO can be used for the treatment of pulmonary hypertensive crisis after surgery for congenital heart disease, especially when it is refractory to conventional measures. We report a case of postoperative pulmonary hypertensive crisis, developed in a 37-year-old male with patent ductus arteriosus with secondary pulmonary hypertension, which was successfully managed including ECMO.