• Journal of Radiation Industry
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• v.17 no.3
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• pp.233-238
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• 2023

This study was conducted to confirm the safety of the operator's radiation exposure in the micro PET-CT image acquisition experiment using the ¹⁸F-FDG. The usage of ¹⁸F-FDG and the exposure dose of handlers were measured at University B in Metropolitan City A, which uses ¹⁸F-FDG for micro PET-CT image acquisition. As a result of the measurement, the exposure dose is far below the effective dose limit of radiation workers, 50 mSv per year, and the equivalent dose limit of 500 mSv per year for hands, feet, and skin. has been measured Since these exposure doses can be further increased according to the number of times of use of ¹⁸F-FDG, it is judged that the exposure dose compared to the handling amount of ¹⁸F-FDG shown in this study can be used as reference data. In addition, as changed environments such as the use of materials other than unopened RI are occurring in education and research environments, such as the use of ¹⁸F-FDG at University B, radiation exposure with more interest in safety management by checking the factors of radiation exposure of the handler concerned We will always do our best to reduce it.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.51-56
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• 2009

Purpose: Recently, most hospitals are introducing the PACS system and use of the system continues to expand. But small-scaled PACS called MicroPACS has already been in use through open source programs. The aim of this study is to prove utility of operating a MicroPACS, as a substitute back-up device for conventional storage media like CDs and DVDs, in addition to the full-PACS already in use. This study contains the way of setting up a MicroPACS with open source programs and assessment of its storage capability, stability, compatibility and performance of operations such as "retrieve", "query". Materials and Methods: 1. To start with, we searched open source software to correspond with the following standards to establish MicroPACS, (1) It must be available in Windows Operating System. (2) It must be free ware. (3) It must be compatible with PET/CT scanner. (4) It must be easy to use. (5) It must not be limited of storage capacity. (6) It must have DICOM supporting. 2. (1) To evaluate availability of data storage, we compared the time spent to back up data in the open source software with the optical discs (CDs and DVD-RAMs), and we also compared the time needed to retrieve data with the system and with optical discs respectively. (2) To estimate work efficiency, we measured the time spent to find data in CDs, DVD-RAMs and MicroPACS. 7 technologists participated in this study. 3. In order to evaluate stability of the software, we examined whether there is a data loss during the system is maintained for a year. Comparison object; How many errors occurred in randomly selected data of 500 CDs. Result: 1. We chose the Conquest DICOM Server among 11 open source software used MySQL as a database management system. 2. (1) Comparison of back up and retrieval time (min) showed the result of the following: DVD-RAM (5.13,2.26)/Conquest DICOM Server (1.49,1.19) by GE DSTE (p<0.001), CD (6.12,3.61)/Conquest (0.82,2.23) by GE DLS (p<0.001), CD (5.88,3.25)/Conquest (1.05,2.06) by SIEMENS. (2) The wasted time (sec) to find some data is as follows: CD ($156{\pm}46$), DVD-RAM ($115{\pm}21$) and Conquest DICOM Server ($13{\pm}6$). 3. There was no data loss (0%) for a year and it was stored 12741 PET/CT studies in 1.81 TB memory. In case of CDs, On the other hand, 14 errors among 500 CDs (2.8%) is generated. Conclusions: We found that MicroPACS could be set up with the open source software and its performance was excellent. The system built with open source proved more efficient and more robust than back-up process using CDs or DVD-RAMs. We believe that the operation of the MicroPACS would be effective data storage device as long as its operators develop and systematize it.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.813-820
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• 2015

We have studied commercialization and process optimization of protective film on transparent conductive coated substrate, nano silver on flexible PET (poly ethylene terephthalate), by means of roll-to-roll micro-gravure coater. Nanosilver on flexible PET substrate is potential materials to replace ITO (indium tin oxide). Protective film is most important to maintain unique silver pattern on top of transparent PET. PSA pressure sensitive adhesives) was developed solely for nano silver on PET and protective film was successfully laminated. We have optimized all process conditions such as coating thickness, line speed and aging time & temperature via experimental design. Transparent conductive film and its protective film developed in this research are commercially available at this moment.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2004.11a
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• pp.40-44
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• 2004

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.10a
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• pp.143-144
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• 2008

We developed that the film fibers which was vacuum-metalized silver on the PET film played a part increasing durable on the alkali, antibiotic and another functional property. For this usage, PET film fibers with fine denier vacuum-metalized silver manufactured through changing the micro slitting machine's drive process.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.177-180
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• 2008

SHCC shows the high energy tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For effective material design and application of SHCC, it is needed to investigate the damage process and micro-fracture mechanism of cement matrix reinforced with different types of fibers. The objective of this paper is to investigate the direct tensile response of cement composites reinforced with single and hybrid fibers using acoustic emission(AE) technique. In this study, the correlations between AE signal and result of the direct tensile response of SHCC. For these purposes, three kinds of fibers were used: PET1.5%, PET1.0+PE0.5%, PET1.0%+PVA0.5%. The result of the direct tensile response of SHCC, for the same volume fraction of fibers, ultimate strength of PET-PE specimen was 2.7 times higher than specimens with PET fibers. And from AE signal value, AE event numbers and cumulative energy were different according to kind of fiber because of the different material properties of reinforced fiber.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.63-70
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• 2022

The development of myocardial perfusion imaging (MPI) agents has been motivated because coronary artery disease has been one of the leading causes of death worldwide since the 1960s. Several positron emission tomography (PET) MPI agents were developed, and ¹⁸F-labeled phosphonium cations were reported actively among them. In this study, we synthesized novel ¹⁸F-labeled phosphonium cations, (5-[¹⁸F]fluoropentyl)diphenyl(pyridin-2-yl)phosphonium and (2-(2-[¹⁸F]fluoroethoxy)ethyl)diphenyl(pyridin-2-yl)phosphonium, and evaluated potential as MPI agents. Two labeled compounds were synthesized via nucleophilic substitution reactions of ¹⁸F-fluoride with the appropriate tosylate precursor in the presence of Kryptofix 2.2.2 and K₂CO₃. MicroPET studies were performed in normal rats to evaluate in vivo distribution of radiolabeled phosphonium cations for 60 min. The radiolabeled compounds were synthesized with 5%-10% yield. The radiochemical purity of labeled compounds was > 98% by analytical HPLC, and the specific activity was > 11.8 GBq/µmol. The result of microPET studies of these labeled compounds in rats showed intense uptake in the myocardium at 30 and 60 min. The results suggest that these ¹⁸F-labeled novel phosphonium cations would have potential as promising candidates for myocardial perfusion imaging.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.21-26
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• 2016

Purpose Because of many advantages, PET-CT Scanners generally use CT Data for attenuation correction. By using CT based attenuation correction, we can get anatomical information, reduce scan time and make more accurate correction of attenuation. However in case metal artifact occurred during CT scan, CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET images. Therefore this study infers true SUV of metal artifact region from attenuation corrected image count -to- non attenuation corrected image count ratio. Materials and Methods Micro phantom inserted $^{18}F-FDG$ 4mCi was used for phantom test and Biograph mCT S(40) is used for medical test equipment. We generated metal artifact in micro phantom by using metal. Then we acquired both metal artifact region of correction factor and non metal artifact region of correction factor by using attenuation correction image count -to- non attenuation correction image count ratio. In case of clinical image, we reconstructed both attenuation corrected images and non attenuation corrected images of 10 normal patient($66{\pm}15age$) who examined PET-CT scan in SNUH. After that, we standardize several organs of correction factor by using attenuation corrected image count -to- non attenuation corrected count ratio. Then we figured out metal artifact region of correction factor by using metal artifact region of attenuation corrected image count -to- non attenuation corrected count ratio And we compared standard organs correction factor with metal artifact region correction factor. Results according to phantom test results, metal artifact induce overestimation of correction factor so metal artifact region of correction factors are 12% bigger than the non metal artifact region of correction factors. in case of clinical test, correction factor of organs with high CT number(>1000) is $8{\pm}0.5%$, correction factor of organs with CT number similar to soft tissue is $6{\pm}2%$ and correction factor of organs with low CT number(-100>) is $3{\pm}1%$. Also metal artifact correction factors are 20% bigger than soft tissue correction factors which didn't happened metal artifact. Conclusion metal artifact lead to overestimation of attenuation coefficient. because of that, SUV of metal artifact region is overestimated. Thus for more accurate quantitative evaluation, using attenuation correction image count -to-non attenuation correction image count ratio is one of the methods to reduce metal artifact affect.

• Advances in concrete construction
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• v.9 no.5
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• pp.479-489
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• 2020

Studies have proved that the mechanical properties of concrete, suddenly is dropped off with employing waste materials as replacements. The effectiveness of fibre addition on the structural stability of concrete has been indicated in recent investigations. There are different waste aggregates and fibres as plastic, rubber tire, coconut, and other natural wastes, which have been evaluated throughout the last decades. The fibres incorporation has a substantial effect on the properties of concrete mix subjected to different loading scenarios. This paper has reviewed different types of wastes and the effect of typical fibres including Poly Ethylene Terephthalate (PET), rubber tire, and waste glass. Furthermore, waste plastic and waste rubber has been especially studied in this review. Although concretes containing PET fibre revealed a reduction in compressive strength at low fibre fractions, using PET is resulted to micro-cracking decrement and increasing flexibility and flexural strength. Finally, according to the reviews, the conventional waste fibres are well-suited to mitigated time-induced damages of concrete and waste fibres and aggregates could be a reliable replacement for concrete.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.22-29
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• 2007

Purpose: Metastatic thyroid cancers with I-131 uptake have been known to show no increase of FDG uptake whereas those without I-131 uptake tend to demonstrate increased uptake on PET. In this study, we evaluated the degree of FDG uptake in primary thyroid cancers of papillary histology before surgery. Material & Methods: Forty FDG PET studies were performed on the patients who had papillary cancer proven by fine needle aspiration. The degree of FDG uptake was visually categorized as positive or negative (positive if the tumor showed discernible FDG; negative if the tumor didn't) and the peak standard uptake value (peak SUV) of the papillary thyroid cancer (PTC) were compared with the size of PTC. Results: The mean size of 26 PTC with positive FDG uptake was $1.9{\pm}1.4\;cm(0.5{\sim}5\;cm)$. In 13 PTC with negative FDG uptake, the mean size of those was $0.5{\pm}0.2\;cm\;(0.2{\sim}0.9\;cm)$. All PTC larger than 1cm ($2.5{\pm}1.4\;cm,\;1{\sim}5\;cm$) have positive FDG uptake (peak $SUV=6.4{\pm}5.7,\;1.7{\sim}22.7$). Among the micropapillary thyroid cancer (microPTC; PTC smaller than 1cm), 8 microPTC show positive FDG uptake(peak $SUV=2.9{\pm}1.3,\;1.7{\sim}5.5$), while 13 microPTC show negative finding(peak $SUV=1.3{\pm}0.2,\;1.1{\sim}1.7$). The size of microPTC with positive FDG uptake is significantly larger than that of microPTC with negative FDG uptake ($0.7{\pm}0.1\;cm$ vs $0.4{\pm}0.2\;cm$, p=0.01). Conclusion: All PTCs larger than 1cm show positive FDG uptake in our study. In other words, thyroid lesions larger than 1cm with negative FDG uptake are unlikely to be PTC. So far, only poorly differentiated thyroid cancers are known to show increased FDG uptake. Our results seem to be contradictory to what is known in the literature. Further study is needed to understand better the significance of increased FDG uptake in PTC in relation to expression of NIS and GLUT.