• Pediatric Infection and Vaccine
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• v.23 no.3
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• pp.165-171
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• 2016

Purpose: Human parechovirus (HPeV) is an increasingly recognized pathogenic cause of central nervous system (CNS) infection in neonates. However, HPeV infections have not been studied in older children. This study determined the prevalence and clinical features of HPeV CNS infection in children in Korea. Methods: Reverse transcription polymerase chain reaction assays were performed using HPeV-specific, 5' untranslated, region-targeted primers to detect HPeV in cerebrospinal fluid (CSF) samples from children presenting with fever or neurologic symptoms from January 1, 2013, to July 31, 2014. HPeV genotyping was performed by sequencing the viral protein 3/1 region. Clinical and laboratory data were retrospectively abstracted from medical records and compared with those of enterovirus (EV)-positive patients from the same period. Results: Of 102 CSF samples, six (5.9%) were positive for HPeV; two of 21 EV-positive samples were co-infected with HPeV. All samples were genotype HPeV3. Two HPeV-positive patients were <3 months of age and four others were over 1 year old. While HPeV-positive infants under 1 year of age presented with sepsis-like illness without definite neurologic abnormalities, HPeV-positive children over 1 year of age presented with fever and neurologic symptoms such as seizures, loss of consciousness, and gait disturbance. The CSF findings of HPeV-positive patients were mostly within the normal range, whereas most (73.7%) EV-positive patients had pleocytosis. Conclusions: Although HPeV is typically associated with disease in young infants, the results of this study suggest that HPeV is an emerging pathogen of CNS infection with neurologic symptoms in older childhood.

• Progress in Medical Physics
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• v.21 no.2
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• pp.137-144
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• 2010

The purpose of this study was to evaluate the usefulness of reducing of craniofacial radiation dose using automatic exposure control (AEC) technique in the 64 multi-detector computed tomography (MDCT). We used SOMATOM Definition 64 multi-detector CT, and head of whole body phantom (KUPBU-50, Kyoto Kagaku CO. Ltd). The protocol were helical scan method with 120 kVp, 1 sec of rotation time, 5 mm of slice thickness and increment, 250 mm of FOV, $512{\times}512$ of matrix size, $64{\times}0.625\;mm$ of collimation, and 1 of pitch. The evaluation of dose reducing effect was compared the fixed tube current of 350 with AEC technique. The image quality was measured the noise using standard deviation of CT number. The range of craniofacial bone was to mentum end from calvaria apex, which devided three regions: calvaria~superciliary ridge (1 segment), superciliary ridge~acanthion (2 segment), and acanthion~mentum (3 segment). In the fixed tube current technique, CTDIvol was 57.7 mGy, DLP was $640.2\;mGy{\cdot}cm$ in the all regions. The AEC technique was showed that 1 segment were 30.7 mGy of CTDIvol, 340.7 $mGy{\cdot}cm$ of DLP, 2 segment were 46.5 mGy of CTDIvol, $515.0\;mGy{\cdot}cm$ of DLP, and 3 segment were 30.3 mGy of CTDIvol, $337.0\;mGy{\cdot}cm$ of DLP. The standard deviation of CT number was 2.622 with the fixed tube current technique and 3.023 with the AEC technique in the 1 segment, was 3.118 with the fixed tube current technique and 3.379 with the AEC technique in the 2 segment, was 2.670 with the fixed tube current technique and 3.186 with the AEC technique in the 3 segment. The craniofacial radiation dose using AEC Technique in the 64 MDCT was evaluated the usefulness of reducing for the eye, the parotid and thyroid with high radiation sensitivity particularly.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.199-211
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• 2002

Digital substraction technique and computer-assisted densitometirc analysis detect minor change in bone density and thus increase the diagnostic accuracy. This advantage as well as high sensitivity and objectivity which precludes human bias have drawn interest in radiologic research area. The objectives of this study are to verify if Radiographic density can be recognized in linear pattern when density profile of standard periapical radiograph with the aluminium stepwedge as the reference, was investigated under varies circumstances which can be encountered in clinical situations, and in addition to that to obtain mutual relationship between the existing standard radiographic system, and future digital image systems, by confirming the corelationship between the standard radiograph and Digora system which is a digital image system currently being used. In order to make quantitative analysis of the bone tissue, digital image system which uses high resolution automatic slide scanner as an input device, and Digora system were compared and analyzed using multifunctional program, Brain3dsp. The following conclusions were obtained. 1. Under common clinical situation that is 70kVp, 0.2 sec., and focal distance 10cm, Al-Equivalent image equation was found to be Y=11.21X+46.62 $r^2=0.9898$ in standard radiographic system, and Y=12.68X+74.59, $r^2=0.9528$ in Digora system, and linear relation was confirmed in both the systems. 2. In standard radiographic system, when all conditions were maintained the same except for the condition of developing solution, Al-Equivalent image equation was Y=10.07X+41.64, $r^2=0.9861$ which shows high corelationship. 3. When all conditions were maintained the same except for the Kilovoltage peak, linear relationship was still maintained under 60kVp, and Al-Equivalent image equation was Y=14.60X+68.86, $r^2=0.9886$ in the standard radiograhic system, and Y=13.90X+80.68, $r^2=0.9238$ in Digora system. 4. When all conditions were maintained the same except for the exposure time which was varied from 0.01 sec. to 0.8 sec., Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9188 to 0.9900, and in general, standard radiographic system showed higher R-square than Digora system. 5. When all conditions were maintained the same except for the focal distance which was varied from 5cm to 30cm, Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9463 to 0.9925, and the standard radiographic system had the tendency to show higher R-square in shorter focal distances.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.1
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• pp.51-56
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• 2015

Purpose As medical radiation exposures on patients are being social issues an interest in a relief of radiation exposures on patients is increasing. Further, there are many cases where some patients among who are getting PET/CT tests choose to get implanted with metal artifacts in their bodies. This study is to find out effects of presence or absence of metal artifacts when dose change or CT attenuation correction for the relief of radiation exposures are applied using phantoms through changes in standard uptake value (SUV). Materials and Methods GE company's Discovery 710 machine was used for PET/CT test equipments. We used NEMA IEC body phantoms. We also used screw and mesh cage made of titanium which are used in real clinical processes for the metal artifacts. Two experiments were conducted: One is to test and measure repeatedly about SUV about differences in CT attenuation corrections according to dose changes and another is to do the same procedure for SUV about the presence and absence of the metal artifacts. We injected $^{18}F-FDG$ into NEMA IEC body phantoms with a TBR ratio of 4:1 and then put the metal material into the transformation phantoms. Once a scanning for the metal artifacts was done we eliminated the metal artifacts and went on non-metal artifacts. For the each two experiments, we scanned repeatedly with CT kVp (140, 120, 100, 80) and mA (120, 80, 40, 20, 10) for an experimental condition. For PET, we reconstructed each with standard AC (STD) technique and quantitation achieved cnsistently QAC) technique among CT attenuation correction methods. We conducted a comparative analysis on measured average values and variations which were measured through repeated measure of SUV of region 1, 2, 3 spheres for each conditions of non-metal /metal scan. Results For each kVp, 120, 80, 40 (mA) of non/metal (screw, mesh cage) showed low frequency of fluctuation rates of above 2%. In 20, 10 mA above 2% of fluctuation rates appeared in high frequency. Also, when we compared the fluctuation rates of STD and QAC techniques in non/metal (screw, mesh cage) tests QAC technique showed about 1-10% of differences for each conditions compared to STD technique. In addition, metal types did not have significant effects on fluctuation rates. Conclusion We confirmed that SUV fluctuation rates for both STD and QAC techniques increase as dosage is lower. We also found that the SUV of PET data was maintained steadily in a low dosage for QAC technique when compared with STD technique. Hence, when the low dosage is used for the relief of radiation exposures on patients QAC technique may be exploited helpfully and this could be applied in the same way for patients with metal artifacts implanted in their bodies.

• Journal of Life Science
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• v.32 no.7
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• pp.532-541
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• 2022

Obesity induced by high-fat diet (HFD) is verified as a strong risk factor and negative prognostic factor for prostate cancer in several genetically engineered mice although it was not examined in the normal mice. To investigate whether HFD-induced obesity can affect the development and progression of cancer in the prostate of normal mice, alterations in the weight and histological structure of the prostate as well as the expression of cancer-related proteins were analyzed in obese C57BL/6N mice fed with 60% HFD for 16 weeks. First, HFD-induced obesity, including an increase in organ weight, body weight, fat accumulation, and serum lipid profile, was successfully induced in C57BL/6N mice after HFD treatment. The total weight of the prostate significantly increased HFD-induced obesity in the model mice compared with the control group. Among the four lobes of the prostate, the weight of the ventral prostate (VP) and anterior prostate (AP) were higher in HFD-induced obesity model mice than in the control group, although the weights of the lateral prostate (DLP) and seminal vesicle (SV) were constantly maintained. In addition, the incidences of hyperplasia and non-hodgkin's lymphoma (NHL) in the histological structure were remarkably increased in HFD-induced obesity model mice, while the epithelial thickness was higher in the same group. A significant increase in the phosphorylation levels of key proteins in the AKT (protein kinase B) signaling pathway was detected in HFD-induced obesity model mice. Therefore, these results suggest that HFD-induced obesity can promote hyperplasia and NHL in the prostates of C57BL/6N mice through the activation of the AKT signaling pathway.

• Progress in Medical Physics
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• v.23 no.3
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• pp.127-137
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• 2012

A conversing beam is firstly designed for radiosurgery by a neurosugern Lars Leksell in 1949 with orthogonal x-rays tube moving through horizontal moving arc to focusing the beam at target center. After 2 decades he composits 201 source of the Co-60 for gamma knife which beams focused at locus. Sveral linac-based stereotactic radiosurgery using the circular collimated beam which size range for 0.4~4.0 cm in a diameter by non-coplanar multiarc have been developed over the decades. The irregular lesions can be treated by superimposing with several spherical shots of radiation over the tumour volume. Linac based techniques include the use of between 4 and 11 non-co-planar arcs and a dynamic rotation technique and use photon beam energies in the range of 6~10 MV. Reviews of the characteristics of several treatment techniques can be found in the literature (Podgorsak 1989, Schell 1991). More in recent, static conformal beams defined by custom shaped collimators or a mini- or micro-multileaf collimator (mMLC) have been used in SRS. Finally, in the last few years, intensity-modulated mMLC SRS has also been introduced. Today, many commercial and in-house SRS programs have also introduced non-invasive immobilization systems include the cyberknife and tomotherapy and proton beam. This document will be compared the characteristics of dose distribution of radiosurgery as introduced gamma knife, BrainLab include photon knife in-house SRS program and cyberknife in currently wide used for a cranial SRS.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.2
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• pp.115-119
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• 2009

I think this will be valuable reference for assuring consistency and homogeneity of clarity and managing dental radiation equipment by experimentation of dental radiation equipment permanent which based on KS C IEC 61223-3-4 standard and KS C IEC 61223-2-7. Put a dental radiation generator and experiment equipment as source and film(sensor) length within 30 em, place the step-wedge above the film(sensor). Tie up tube voltage 60 kVp, tube current 7 mA and then get an each image through CCD sensor and film by changing the exposure time as 0.12sec, 0.25sec, 0.4sec. Repeat the test 5times as a same method. Measure the concentration of each stage of film image, which gained by experiment, using photometer. And the image that gained by CCD sensor, analyze the pixel value's change by using image J, which is analyzing image program provided by NIH(National Institutes of Health). In case of film, while 0.12sec and 0.25sec show regular rising pattern of density gap as exposure time's increase, 0.4sec shows low rather than 0.12sec and 0.25sec. In case of CCD sensor density test, the result shows opposite pattern of film. This makes me think that pixels of CCD's sensor can have 0~255 value but it becomes saturation if the value is over 255. The way that getting clear reception during decreasing human's exposed radiation is one of maintaining an equipment as a best condition. So we should keeping a dental radiation equipment's condition steadily through cyclic permanent test after factor examination. Even digital equipment doesn't maintain a permanent, it can maintain a clarity by post processing of image so that hard to set it as standard of permanent test. Therefore it would be more increase the accuracy that compare a film as standard image. Thus I consider it will be an important measurement to care for dental radiation equipment and warrant homogeneity, consistency of dental image's clarity through comparing pattern which is the result from factor test against cyclic permanent test.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.501-507
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• 2016

This study is to figure out the amount of primary X-ray generated in SID 50cm, 1m, and 2m penetrating protective aprons in X-ray radiography for hands, skull, and lumbar spine. Results are as follows: Firstly, the exposure dose of primary X-ray which is low such as that of hand X-ray may be reduced by 270 times if protective aprons are worn, but it still slightly penetrates 0.3mm thick Pb protective aprons at SID 50cm, 1m, and 2m. Secondly, the exposure dose of primary X-ray which is moderate such as that of skull X-ray may be reduced by 22 times if protective aprons are worn, but it still fairly penetrates 0.3mm thick Pb protective aprons at SID 50cm, 1m, and 2m. Thirdly, the exposure dose of primary X-ray which is very high such as that of lumbar spine X-ray may be reduced by 13 times if protective aprons are worn, but it still penetrates a lot 0.3mm thick Pb protective aprons at SID 50cm, 1m, and 2m. Therefore, people in X-ray room should not only wear protective aprons at any spaces that the primary X-ray can reach, but also need to stand behind the thick Pb shield to protect the body if it is inevitable to stay in the room.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.3_4
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• pp.61-71
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• 1995

Natural ground is a composite consisted of the three phases of water, air and soil paircies. Among the three components, water as a material is weU understood but soil particles are not in foundation engineering. Especially, weathered granite soil generally shows a large volumetric expansion when they freeze. And, the stability and durability of the soil have shown decreased with repetitive freezing and thawing processes. These unique charcteristics may cause various construction and management problems if the soil is used as a construction material and foundation layers. This project was initiated to investigate the soil's physical and engineering characteristics resulting from freezing and freezing-thawing processes. Research results may be used as a basic data in solving various problems related to the soil's unique characteristics. The following conclusions were obtained: The degree of decomposition of weathered granite soil in Kangwon-do was very different between the West and East sides of the divide of the Dae-Kwan Ryung. Soil particles distributed wide from very coarse to fine particles. Consistency could be predicted with a function of P200 as LL=0.8 P200+20. Permeability ranged from 10-2 to 10-4cm/sec, moisture content from 15 to 20% and maximum dry density from 1.55 to 1.73 g /cmΥ$^3$ By compaction, soil particles easily crushed, D50 of soil particles decreased and specific surface significantly increased. Shear characteristics varied wide depending on the disturbance of soil. Strain characteristics influenced the soil's dynamic behviour. Elastic failure mode was observed if strain was less than 1O-4/s and plastic failure mode was observed if strain was more than 10-2/s. The elastic wave velocity in the soil rapidly increased if dry density became larger than 1.5 g /cm$^3$ and these values were Vp=250, Vg= 150, respectively. Frost heave ratio was the highest around 0 $^{\circ}C$ and the maximum frost heave pressure was observed when deformation ratio was less than 10% which was the stability state of soil freezing. The state had no relation with frost depth. Over freezing process was observed when drainage or suction freezing process was undergone. Drainage freezing process was observed if freezing velocity was high under confined pressure and suction frost process was occurred if the velocity was low under the same confined process.

• Imaging Science in Dentistry
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• v.48 no.2
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• pp.97-101
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• 2018

Purpose: This study evaluated the radiopacity of contemporary luting cements using conventional and digital radiography. Materials and Methods: Disc specimens (N=24, n=6 per group, ø$7mm{\times}1mm$) were prepared using 4 resin-based luting cements (Duolink, Multilink N, Panavia F 2.0, and U-cem). The specimens were radiographed using films, a complementary metal oxide semiconductor (CMOS) sensor, and a photostimulable phosphor plate (PSP) with a 10-step aluminum step wedge (1 mm incremental steps) and a 1-mm-thick tooth cut. The settings were 70 kVp, 4 mA, and 30 cm, with an exposure time of 0.2 s for the films and 0.1 s for the CMOS sensor and PSP. The films were scanned using a scanner. The radiopacity of the luting cements and tooth was measured using a densitometer for the film and NIH ImageJ software for the images obtained from the CMOS sensor, PSP, and scanned films. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: Multilink (3.44-4.33) showed the highest radiopacity, followed by U-cem (1.81-2.88), Panavia F 2.0 (1.51-2.69), and Duolink (1.48-2.59). The $R^2$ values of the optical density of the aluminum step wedge were 0.9923 for the films, 0.9989 for the PSP, 0.9986 for the scanned films, and 0.9266 for the CMOS sensor in the linear regression models. Conclusion: The radiopacities of the luting materials were greater than those of aluminum or dentin at the same thickness. PSP is recommended as a detector for radiopacity measurements because of its accuracy and convenience.