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Development of a polystyrene phantom for quality assurance of a Gamma Knife®
최요나,전국진,방정배,최상현,조규석,김태훈,양혜정,서영찬,정현태 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8
A polystyrene phantom was developed following the guidance of the International Atomic Energy Association (IAEA) for gamma knife (GK) quality assurance. Its performance was assessed by measuring the absorbed dose rate to water and dose distributions. The phantom was made of polystyrene, which has an electron density (1.0156) similar to that of water. The phantom included one outer phantom and four inner phantoms. Two inner phantoms held PTW T31010 and Exradin A16 ion chambers. One inner phantom held a film in the XY plane of the Leksell coordinate system, and another inner phantom held a film in the YZ or ZX planes. The absorbed dose rate to water and beam profiles of the machine-specific reference (msr) field, namely, the 16 mm collimator field of a GK Perfexion™ or Icon™, were measured at seven GK sites. The measured results were compared to those of an IAEA-recommended solid water (SW) phantom. The radius of the polystyrene phantom was determined to be 7.88 cm by converting the electron density of the plastic, considering a water depth of 8 g/cm2 . The absorbed dose rates to water measured in both phantoms differed from the treatment planning program by less than 1.1%. Before msr correction, the PTW T31010 dose rates (PTW Freiberg GmbH, New York, NY, USA) in the polystyrene phantom were 0.70 (0.29)% higher on average than those in the SW phantom. The Exradin A16 (Standard Imaging, Middleton, WI, USA) dose rates were 0.76 (0.32)% higher in the polystyrene phantom. After msr correction factors were applied, there were no statistically significant differences in the A16 dose rates measured in the two phantoms; however, the T31010 dose rates were 0.72 (0.29)% higher in the polystyrene phantom. When the full widths at half maximum and penumbras of the msr field were compared, no significant differences between the two phantoms were observed, except for the penumbra in the Y-axis. However, the difference in the penumbra was smaller than variations among different sites. A polystyrene phantom developed for gamma knife dosimetry showed dosimetric performance comparable to that of a commercial SW phantom. In addition to its cost effectiveness, the polystyrene phantom removes air space around the detector. Additional simulations of the msr correction factors of the polystyrene phantom should be performed.
최요나,천국진,김은산,장영재,박지애,김금배,김근희,최상현 한국의학물리학회 2021 의학물리 Vol.32 No.4
Purpose: In this study, we aimed to manufacture a patient-specific gel phantom combining three- dimensional (3D) printing and polymer gel and evaluate the radiation dose and dose profile using gel dosimetry. Methods: The patient-specific head phantom was manufactured based on the patient’s computed tomography (CT) scan data to create an anatomically replicated phantom; this was then produced using a ColorJet 3D printer. A 3D polymer gel dosimeter called RTgel-100 is contained inside the 3D printing head phantom, and irradiation was performed using a 6 MV LINAC (Varian Clinac) X-ray beam, a linear accelerator for treatment. The irradiated phantom was scanned using magnetic resonance imaging (Siemens) with a magnetic field of 3 Tesla (3T) of the Korea Institute of Nuclear Medicine, and then compared the irradiated head phantom with the dose calculated by the patient's treatment planning system (TPS). Results: The comparison between the Hounsfield unit (HU) values of the CT image of the patient and those of the phantom revealed that they were almost similar. The electron density value of the patient’s bone and brain was 996±167 HU and 58±15 HU, respectively, and that of the head phantom bone and brain material was 986±25 HU and 45±17 HU, respectively. The comparison of the data of TPS and 3D gel revealed that the difference in gamma index was 2%/2 mm and the passing rate was within 95%. Conclusions: 3D printing allows us to manufacture variable density phantoms for patient-specific dosimetric quality assurance (DQA), develop a customized body phantom of the patient in the future, and perform a patient-specific dosimetry with film, ion chamber, gel, and so on.
이유자돈 사료 내 동애등에(Hermetia illucens )의 첨가수준이 사양성적, 영양소소화율 및 경제성에 미치는 영향
최요한(Yo-Han Choi),윤세영(Se-Yeong Yoon),전세민(Se-Min Jeon),이재영(Jae-Young Lee),오승민(Seung-Min Oh),이승형(Seung-Hyung Lee),김진수(Jin-Soo Kim) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.9
본 시험은 이유자돈 사료 내 동애등에(Hermetia illucens )의 사용 수준에 따른 성장, 영양소소화율 및 경제성을 평가하여 이유자돈 사료 내 동애등에의 적정 사용수준을 도출하기 위해 실시하였다. 본 시험을 위해 총 192 두의 이유자돈(Landrace × Yorkshire × Duroc; 6.51 ± 0.15 kg)을 공시하여 4 처리 6 반복, 반복당 8 두씩 완전임의 배치하였다. 시험 처리구는 옥수수-대두박 기초사료를 대조구로 하여 기초사료 내 동애등에를 각각 1, 2 및 3% 첨가하였다. Phase Ⅰ, Ⅱ 및 overall의 사양성적에서 유의적인 차이가 나타나지 않았으나, overall의 일당증체량에서 동애등에 첨가수준에 따라 선형적으로 증가하는 것으로 나타났다(p < 0.05). 건물 소화율이 동애등에 첨가수준에 따라 유의적으로 증가하는 것으로 나타났으나, 다른 항목에서 유의적인 효과는 나타나지 않았다. 경제성 분석에서 overall의 총증체량이 동애등에의 첨가수준이 증가함에 따라 증가하였으며(p < 0.05), 이를 제외한 모든 항목에서 유의적인 효과가 나타나지 않았다. 본 연구결과를 요약하면, 사료 내 동애등에의 첨가는 경제성의 영향 없이 이유자돈의 성장과 건물 영양소소화율 개선에 유의한 효과를 미치며, 이는 이유자돈 사료 내 3%까지 사용이 가능한 것을 시사한다. This trial was conducted to determine the optimal supplementation level of Hermetia illucens (HI) on the growth performance, the apparent total tract retention of nutrients and the economic efficiency in weaning pigs. A total of 192 weaned pigs (Landrace × Yorkshire × Duroc; 6.51 ± 0.15 kg) were randomly allotted to 4 treatments and 6 replicates on the basis of their initial body weight. The dietary treatments included a corn-soybean meal based diet supplemented with 0, 1, 2 or 3% HI. There were no significantly effects between the treatments in phases Ⅰ, Ⅱ and overall. But average daily gain was significant and linearly increased when HI was added to the diet in the overall group. Although digestibility of dry matter (DM) was increased by adding HI, digestibility responses were not observed by supplying HI in phase Ⅰ. Also, all the parameters of economic efficiency were not significantly different according to the level of HI. The results showed that HI had beneficial effects on growth performance and digestibility of dry matter. However, there were no effects on economic efficiency by using HI in weaning pig diets.
사람 호흡기 상피세포에서 MUC5B 발현에 대한 Polyinosinic-Polycytidylic Acid의 효과
최요한,배창훈,김형근,서보현,최윤석,송시연,김용대 대한이비인후과학회 2015 대한이비인후과학회지 두경부외과학 Vol.58 No.9
Background and Objectives Polyinosinic-polycytidylic acid (Poly I:C) is structurally similar to double-stranded RNA, and is known to induce various inflammatory mediators and to cause inflammatory reactions in airway epithelial cells. However, the effect of Poly I:C on secretion of mucins in human airway epithelial cells has been very rarely reported. In this study, the effect and brief signaling pathway of Poly I:C on the expression of mucin genes were investigated in human airway epithelial cells. Materials and Method In mucin-producing human NCI-H292 airway epithelial cells and the primary cultures of normal human nasal epithelial cells, the effect and signaling pathway of Poly I:C on expression of mucin genes were investigated using reverse transcriptase-polymerase chain reaction, real-time PCR, enzyme immunoassay, and immunoblot analysis with specific inhibitors and small interfering RNA (siRNA) for mitogen-activated protein kinase (MAPK). Results Poly I:C induced the MUC5B expression, and activated the phosphorylation of ERK1/2 and p38 MAPK. U0126 (ERK1/2 MAPK inhibitor) and SB203580 (p38 MAPK inhibitor) inhibited the Poly I:C-induced MUC5B expression. In addition, the knockdown of ERK2 and p38 MAPK by siRNA significantly blocked the Poly I:C-induced MUC5B mRNA expression. Conclusion Poly I:C induces the MUC5B expression via ERK2 and p38 MAPK signaling pathways in human airway epithelial cells. Therefore, Poly I:C may play a role in the regulation of mucus hypersecretion through MAPK signaling pathways in the human airway epithelial cells.
최요한 한국보건사회연구원 2020 保健社會硏究 Vol.40 No.2
In order to estimate the temporary-permanent workers’ wage gap which is caused by the difference in contract types across the marginal wage distribution with controlling for individual unobserved heterogeneity, recent studies applied UQR (unconditional quantile regression) with individual FE (fixed-effects). Since, as a dependent variable, UQR uses the RIF (recentered influence function) which has a binary outcome, UQR is a BPM (binary probability model) that has a theoretical interest in the effects on a latent dependent variable which is continuous. Based on the empirical results of Firpo et al. (2009) and the widely held belief that a LPM (linear probability model) well approximates a BPM, subsequent studies have generally used a LPM instead of a BPM. In the case of controlling for individual FE, linear FE regression and logistic FE regression can be used for a LPM and a BPM, respectively. However, these two regressions have a critical difference that individuals having no longitudinal variation in the RIF are excluded in logistic FE regression and not in linear FE regression. In a strict sense, however, individuals having no longitudinal variation in the RIF have to be excluded from the sample because the partial effects of explanatory variables on a latent continuous dependent variable are not non-existent but just not identified in these individuals. By analyzing panel data of South Korea, I find that the inclusion of individuals having no longitudinal variation in the RIF substantially underestimates both the temporary-permanent wage gap and the confidence interval of that, especially at the extreme quantiles. Even so, if the aim of the study is to just use the within-variance and not to strictly control for individual FE based on the binary choice model, it could be possible to include individuals having no longitudinal variation in a dependent variable in the analysis.