Paraffin을 이용한 Thyroid Phantom제작에 따른 유용성에 관한 연구

박성옥(Soung-Ock Park),이인자(In-Ja Lee) 대한방사선과학회(구 대한방사선기술학회) 2007 방사선기술과학 Vol.30 No.3

  방사성의약품을 이용한 핵의학적 영상기록에 있어 장기가 함유하고 있는 정보량을 최대한 묘출시켜 양질의 진단정보를 제공해야 한다는 것은 매우 중요하다. 그것을 위한 기술적인 문제를 비롯하여 장비성능의 유지관리에 많은 노력을 기울이고 있으며, 다양한 종류로 상업화되어 이용되고 있는 우수한 phantom들이 사용되고 있다.<BR>  본 연구에서 인체의 연부조직과 매우 흡사한 물리적 조건을 가지고 있으며 구입하기 쉬운 Paraffin을 이용하여 기존에 사용되고 있는 acryl thyroid phantom과 동일하게 paraffin phantom을 제작하였으며, 판매되고 있는 acryl thyroid phantom에서 측정할 수 있는 것 보다 더 높은 분해능을 측정할 수 있도록 작은 3 mm와 6 mm 직경의 cold area를 삽입한 paraffin thyroid phantom을 수작업으로 제작하였다. 방사성의약품 <SUP>99m</SUP>TcO4를 이용하고 pinhole collimator를 이용하여 상업화되어 사용되고 있는 acryl thyroid phantom과 본 연구를 위하여 제작한 paraffin thyroid phantom의 특성을 비교 분석한 결과 paraffin을 이용한 phantom도 상업화되어 사용 중인 acryl thyroid phantom과 동일한 물리적 특성을 유지하고, 오히려 분해능이 높은 부분을 측정할 수 있고 연부조직의 특성을 연구할 수 있는 등가물질로서 구입하기 쉽고 제작이 수월한 장점을 비롯하여 경제성이 있음을 증명하는 계기가 되었다.   Phantoms are very necessary for quality assurance of radio nuclides imaging systems to maintain standards and to ensure reproducibility of test. General quality assurance and instrument quality control are essential in every hospital. The human tissue equivalent materials are aluminum, arcryl, water and epoxy .. etc. It is very important to select optimum equivalant materials for a phantoms in QC ..<BR>  Especially, paraffin is very similar with human soft tissue in X or Gamma-ray physical characteristics and easy to buy wiith economically.<BR>  We made a paraffin thyroid phantom and compare with thyroid arcryl phantom, also used commercially in practice. Two small size cold spots (3 and 6 mm diameter) and a hot spot (3 mm diameter) embeded in paraffin phantom. And imaged with <SUP>99m</SUP>TcO₄ by camera for analysis about spatial resolution and noise at the hot and cold spots.<BR>  We got some results as below:<BR>  1. No difference in counting rate and noise between both arcryl and paraffin thyroid phantoms.<BR>  2. The best spatial resolution can be seen 6 cm distance between pinhole collimator and thyroid phantoms(arcryl and paraffin).<BR>  3. More optimal spatial resolution could acquired in paraffin thyroid phantom.<BR>  Paraffin is very similar with human soft tissue in atomic number, density and relative absorbtion fuction, and can be shaped easily what we wanted.<BR>  So we can recommendation paraffin as quality assurance phantom because its usefulness, economical benefit and purchasability.

Characteristics of Paraffin Solidification Drum With Boron-Containing Radioactive Liquid Waste Dry Powder

So Jung Shim,Seung Su Shin,Chang Heon Lee,Young-Ku Choi 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

Radioactive liquid waste generated during the operation of domestic nuclear power plants is treated through a somewhat different liquid radwaste system (LRS) for each plant. Prior to the introduction of standard nuclear power plants, LRS used a concentrated water dry system (CWDS) to evaporate liquid waste and manage it in the form of dry powder. The boron-containing radioactive liquid waste dry powder was solidified using paraffin from 1995 to 2010, and about 3,650 drums (based on 200 L) of paraffin solidified drums are currently stored in nuclear power plants. Paraffin solidification drums do not meet the acceptance criteria for radioactive waste repositories because it is difficult to secure the homogeneity of the solidified body and there are concerns about leaching of radioactive waste due to the low melting point of paraffin. In order to solve this problem and safely permanently dispose of paraffin solidification drums, the characteristics of dry powder paraffin solidification drums containing boron-containing radioactive liquid waste must be analyzed and appropriate treatment technology utilizing the results must be introduced. This study analyzes the physical properties of paraffin, the chemical properties of boron-containing radioactive waste dry powder, and the physicochemical properties of paraffin solidification powder, and proposes an appropriate alternative technology for treating boron-containing radioactive waste dry drum. When disposing of the paraffin solidification drum with boron-containing radioactive liquid waste dry powder, the solidification body must be effectively withdrawn from the drum and the paraffin must be completely separated from the solidification body. When disposing the drum, the solidified material must be effectively extracted from the drum and the paraffin must be completely separated from the solidified material. Afterwards, the paraffin must be self-disposed, and the radioactive waste must be disposed of in accordance with acceptance criteria of repository. We looked at how each characteristic of the paraffin solidification drum with boron-containing radioactive liquid waste dry powder can be utilized in each of the above treatment processes.

Design of a Pure Paraffin Separating Machine From Concentrated Waste Solidified With Paraffin by Using Heating Vaporization and Pressure Difference

Tae-Yang Noh,Byeong-Mok Park,Cheol-Wan Park,Ah-Ran Cha,Sang-Hwan Jun,Seong-Won Baek 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

In domestic nuclear power plants, drums of concentrated radioactive waste solidified with paraffin that do not meet radioactive waste disposal standards are stored temporarily. In this paper, the design of a machine that separates these paraffin drums into paraffin and concentrated waste using heating vaporization and pressure difference is described. The separation process is as follows. First, the paraffin solid is indirectly heated by heating the outside of the drum. The paraffin solid is partially melted to increase the fluidity and is easily detached from the drum. The detached solid is transferred to the melting tank, and further heated in the melting tank. When the temperature is sufficiently high, paraffin is melted and becomes a mixture of liquid paraffin and concentrated waste homogeneously. The mixed solution is transferred to a paraffin recovery vessel and further heated. The vaporization point of paraffin is 370°C under atmospheric pressure, and becomes lower depending on the pressure decreasing in the vessel. The vaporization point of the paraffin is a relatively low value compared to the radioactive elements in the concentrated waste, and therefore only paraffin would be vaporized. A paraffin transfer pipe is installed on the upper part of the paraffin recovery vessel, and is connected to another tank called the paraffin capture vessel. The pressure of the paraffin capture vessel is reduced (i.e. vacuum condition), only gaseous paraffin is transferred to the paraffin capture vessel by the pressure difference. When the paraffin capture vessel is cooled below the vaporization point of the paraffin, the paraffin is liquefied or solidified, and only the paraffin is recovered. Based on the above process, the solidified paraffin could be separated into pure paraffin and concentrated waste. However, if a radioactive element with a lower vaporization point than paraffin exists in the concentrated waste, it may be mixed with paraffin and separated together. Therefore, it is necessary to measure the radioactivity or radiation dose rate for the separated paraffin, and to verify that it is sufficiently low. If necessary, additional separation process may be considered for removing radioisotopes from the paraffin.

Changes in microporous structure of polyethylene membrane fabricated from PE/PTMG/paraffin ternary mixtures

Roh, S.C.,Park, M.J.,Yoo, S.H.,Kim, C.K. Elsevier 2012 Journal of membrane science Vol.411 No.-

<P><B>Highlights</B></P><P>► Microporous PE membranes were fabricated via a TIPS process. ► A PTMG mixture with paraffin was used as a novel diluent. ► Phase separation temperature of PE–paraffin–PTMG blend increased up to 270°C. ► PE membranes with average pore sizes between 0.2 and 12μm can be produced.</P> <P><B>Abstract</B></P><P>Polyethylene (PE) membranes containing controlled pore sizes and porosities were fabricated using a polytetramethylene glycol (PTMG) mixture with paraffin as a novel diluent via a thermally induced phase separation (TIPS) process. PTMG could not be used as a diluent alone regardless of its molecular weight because it does not form a single phase mixture with PE over the entire temperature range. However, PTMG and paraffin mixtures, which exhibited upper critical solution temperature (UCST) type phase behavior, formed miscible blends with PE at elevated temperatures. The phase separation temperature of the PE//(paraffin/PTMG) ternary mixture increased with increasing PTMG content in the diluent mixture when PE content was fixed. At a fixed blend composition, the phase separation temperature of the PTMG/paraffin mixture increased as the molecular weight of the PTMG decreased, while that of the PE//(paraffin/PTMG) ternary mixture increased with increasing PTMG molecular weight. The observed phase behavior was attributed to the intermolecular association behavior of PTMG. The phase separation temperature in the PE//(paraffin/PTMG) ternary blend could be increased up to the evaporation temperature of paraffin by controlling the PTMG content or its molecular weight. As a consequence, a PE membrane containing controlled pores and porosities was able to be fabricated using a diluent mixture containing PTMG and paraffin.</P>

Modified paraffin wax for improvement of histological analysis efficiency

Lim, Jin Ik,Lim, Kook-Jin,Choi, Jin-Young,Lee, Yong-Keun Wiley Subscription Services, Inc., A Wiley Company 2010 Microscopy research and technique Vol.73 No.8

<P>Paraffin wax is usually used as an embedding medium for histological analysis of natural tissue. However, it is not easy to obtain enough numbers of satisfactory sectioned slices because of the difference in mechanical properties between the paraffin and embedded tissue. We describe a modified paraffin wax that can improve the histological analysis efficiency of natural tissue, composed of paraffin and ethylene vinyl acetate (EVA) resin (0, 3, 5, and 10 wt %). Softening temperature of the paraffin/EVA media was similar to that of paraffin (50–60°C). The paraffin/EVA media dissolved completely in xylene after 30 min at 50°C. Physical properties such as the amount of load under the same compressive displacement, elastic recovery, and crystal intensity increased with increased EVA content. EVA medium (5 wt %) was regarded as an optimal composition, based on the sectioning efficiency measured by the numbers of unimpaired sectioned slices, amount of load under the same compressive displacement, and elastic recovery test. Based on the staining test of sectioned slices embedded in a 5 wt % EVA medium by hematoxylin and eosin (H&E), Masson trichrome (MT), and other staining tests, it was concluded that the modified paraffin wax can improve the histological analysis efficiency with various natural tissues. Microsc. Res. Tech. 73:761–765, 2010. © 2010 Wiley-Liss, Inc.</P>

Experimental investigation of the effects of paraffin/aluminum blended fuels on aluminum particle size

한성주,문희장 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

The combustion behavior of paraffin/aluminum blended fuels was investigated to determine the effects on the size of nano- and microsized aluminum particles and assess their respective combustion performance in hybrid rocket applications. The base paraffin fuel considered in this study was Sasol 0907 microcrystalline wax. Two additional blended fuels, each with particles with average sizes of 8 µm and 100 nm were used. The thermal and rheological behavior of the paraffin/aluminum blended fuels were evaluated, and their homogeneity was verified by scanning electron microscopy. Results confirmed that the nano-sized and micro-sized particles were well distributed in space without agglomeration. The average regression rate of the paraffin added with micro-sized particles was higher than that of the case with nano-sized particles mainly because of the strong viscosity of the nanofuel. This result was justified by the augmented average chamber pressure of the micro-sized paraffin fuel. Generally, the characteristic velocity of the microfuel was greater than that of the nanofuel for the overall range of the oxidizer-to-fuel ratio considered in this study. This difference became pronounced as the oxidizer mass flux increased. The characteristic velocity efficiency of the two blended fuels (microfuel and nanofuel) merely showed a notable difference in the oxidizer-to-fuel ratio range, except for the particle-free base fuel, which showed a wide scatter of combustion efficiency probably because of its low melt layer viscosity, which leads to an undesirable high entrainment of non-combusted pure paraffin fuel.

Fabrication of paraffin/reduced graphene oxide composite for heat storage

이경섭,장정식 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

In this study, paraffin/reduced graphene oxide (rGO) composites were fabricated by simple and environmentally friendly method. rGO filled with paraffin enhanced thermal properties of paraffin, which has low thermal conductivity (~0.2W/m·K). Paraffin/rGO composites were characterized by SEM, DSC, TGA, PPMS with different weight fraction of rGO in composite. Results indicate that when increasing weight fraction of rGO, thermal conductivity and stability also increased while there was no decrease in heat of fusion because of low fraction of rGO. Paraffin/rGO composite can be a good candidate for latent heat storage with enhanced thermal properties which can be utilized in even harsher environment.

Synthesis of Monodispersed Paraffin Microcapsules by Polycondensation Using Membrane Emulsification and Their Latent Heat Properties

정연석,유진오,염경호 한국고분자학회 2015 Macromolecular Research Vol.23 No.11

Microencapsulation technique of phase change materials (PCMs) has been attracted as one of effective methods to store and transfer the energy. Although the size control of microcapsules as PCMs is very important, it still remains a key issue to resolve. In this study, monodispersed paraffin microcapsules with silica shell were fabricated by membrane emulsification and thermal properties were investigated for the application of energy saving wallpaper. Particle size analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry were used for microcapsule characterization. As results, uniform size of paraffin microcapsules (mean diameter 5 μm) was obtained at high N2 pressure and low surfactant concentration using membrane emulsification and silica shell was successfully synthesized by polycondensation. Also, their latent heat properties were significantly improved compared to pure paraffin. Finally, membrane emulsification is very effective technique to fabricate paraffin microcapsules with feasible size control. Since paraffin microcapsules have high latent heat with thermal stability, those can be used for the application of functional wallpaper as well as building structure materials for saving energy.

파라핀 기반의 조직회수도구를 사용한 채취 조직의 진단 프로토콜 개발

정효영,구교인,이상민,박호수,홍석준,방승민,송시영,조동일,Jeong, Hyo-Young,Koo, Kyo-In,Lee, Sang-Min,Park, Ho-Soo,Hong, Suk-Jun,Bang, Seoung-Min,Song, Si-Young,Cho, Dong-Il 대한의용생체공학회 2010 의공학회지 Vol.31 No.3

We have developed and reported several micro-spikes for minimally invasive biopsy. This paper presents a diagnosis protocol for micro-spike biopsy using paraffin-based tissue collecting tool. Using the proposed tissue collecting tool, which has a negative micro-spike structure in a porous chamber, the biopsied tissue in a micro-spike is effectively detached. The proposed diagnosis protocol prevents the loss of tissues in a paraffin embedding and sectioning process. Hence, it is compatible with conventional histopathology without additional reagents and processes. The gastro-intestinal tissue of a pig is biopsied in an in vivo environment, and then it is detached from a micro-spike using the paraffin-based tissue collecting tool. A histopathological photomicrograph of the detached tissue is acquired with the proposed diagnosis protocol. The acquired image offers clinical quality. This result shows that the paraffin-based tissue collecting tool is applicable to the medical practice.

Isolation, Identification, and Performance Studies of a Novel Paraffin-degrading Bacterium of Gordonia amicalis LH3

Dong-Hui Hao,Xin Song,Jian-Qiang Lin,Yu-Jie Su,Yin-Bo Qu,Jian-Qun Lin 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1

In this study, we describe the isolation and identification of a novel long-chain n-alkane degrading strain, Gordonia amicalis LH3. Under aerobic conditions, it utilized approximately 18.0% of paraffin (2% w/v) after 10 day of incubation, and the paraffin compositions of C18C24 alkalines were utilized preferentially. Under anaerobic conditions, paraffin utilization was approximately 1/8 that seen under aerobic conditions, and the compositions of C34 and C36 alkalines were utilized preferentially. The effects of salinity, temperature, and biosurfactants on paraffin degradation were also evaluated. The strain was also demonstrated to grow on oil, and decreased oil viscosity by 44.7% and degraded oil by 10.4% under aerobic conditions. Our results indicated that G. amicalis LH3 has potential applications in paraffin control, microbial enhanced oil recovery (MEOR), and the bioremediation of hydrocarbon-polluted environments.