• 대한방사성의약품학회지
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• 제4권1호
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• pp.32-35
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• 2018

Since utilization of metal is attractive research area applicable to medical applications, several metals have been studied by many scientists. Zr-89 is known as one of important radioisotopes nowadays. Novel ligands for Zr-89 have been developed, and Zr-89-based radiopharmaceuticals have been employed for positron emission tomography (PET) study. In this highlight review, recent advances on Zr-89 utilization for radiophramaceuticals are illustrated.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.82-85
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• 2004

Flux-enhancement mechanism of thin-film-composite (TFC) membranes for the reverse comosis (RO) process was newly explained by positron annihilation lifetime spectroscopy (PALS) that has been found to be applied for detecting molecular vacancies or pores having sizes that are equivalent to salt or hydrate ions in RO membrane.(omitted)

• 대한핵의학회지
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• 제36권1호
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• pp.74-79
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• 2002

In addition to the well-established use of positron emission tomography (PET) in clinical oncology, novel roles for PET are rapidly emerging in the field of gene therapy. Methods for controlled gene delivery to living bodies, made available through advances in molecular biology, are currently being employed in animals for research purposes and in humans to treat diseases such as cancer. Although gene therapy is still in its early developmental stage, it is perceived that many serious illnesses could be treated successfully by the use of therapeutic gene delivery. A major challenge for the widespread use of human gene therapy is to achieve a controlled and effective delivery of foreign genes to target cells and subsequently, adequate levels of expression. As such, the availability of noninvasive imaging methods to accurately assess the location, duration, and level of transgene expression is critical for optimizing gene therapy strategies. Current endeavors to achieve this goal include methods that utilize magnetic resonance imaging, optical imaging, and nuclear imaging techniques. As for PET, reporter systems that utilize genes encoding enzymes that accumulate positron labeled substrates and those transcribing surface receptors that bind specific positron labeled ligands have been successfully developed. More recent advances in this area include improved reporter gene constructs and radiotracers, introduction of potential strategies to monitor endogenous gene expression, and human pilot studies evaluating the distribution and safety of reporter PET tracers. The remarkably rapid progress occurring in gene imaging technology indicates its importance and wide range of application. As such, gene imaging is likely to become a major and exciting new area for future application of PET technology.

• 한국방사선학회논문지
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• 제6권6호
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• pp.489-493
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• 2012

양전자소멸법은 양전자와 전자가 만나 소멸하면서 발생하는 광자로부터 물질의 상태를 간접적으로 파악하는 실험 방법이다. 본 연구에서는 다양한 분야에서 널리 사용되고 있는 폴리머인 CR, EPDM, NBR에 대하여 양전자소멸법을 통해 양전자 소멸시간을 측정하였다. 한국원자력연구원의 Na-22 선원을 이용한 양전자소멸시간측정장치를 통해 양전자소멸시간의 세가지 수명과 세기를 측정하였다. 이중 세 번째 수명성분은 폴리머의 자유부피와 직접적으로 관계된다. Tao-Eldrup 모델을 이용하여 3가지 폴리머에 대한 자유부피를 측정하였다. 그 결과 CR, EPDM, NBR의 자유부피와 상대비율은 각각 $0.1217nm^3$(1.910%), $0.1478nm^3$(5.315%), $0.1216nm^3$(2.638%)로 나타났다. 이를 통해 양전자소멸법의 폴리머에 대한 적용성을 확인할 수 있었으며 향후 비파괴적으로 폴리머의 특성변화를 분석하는 자료로 활용될 수 있을 것이다.

• 한국재료학회지
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• 제16권7호
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• pp.455-459
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• 2006

Coincidence Doppler Broadening (CDB) of positron annihilation spectroscopy was applied to analyze defects in the chemical state of Department of Physics, $Gd_2O_2S$:Tb intensifying screens. The screen samples were irradiated by 80 MV X-rays in hospital and were used for 0, 2, 4, and 6 years respectively. There was a positive relationship between the S-parameter values and time of exposure to X-rays. Most of the defects were indicated to have been generated by X-rays. A 1D CDB was developed in order to reduce the background noise, and the S-parameter values of the $Gd_2O_2S$:Tb intensifying screens, using the 1D CDB, varied between 0.4974 and 0.4991.

• 대한치매학회지
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• 제17권3호
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• pp.90-99
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• 2018

Background and Purpose: To explore anatomic substrate of specific wandering patterns in patients with Alzheimer's disease (AD) by performing positron emission tomography with $^{18}F$ fluorodeoxyglucose positron emission tomography (FDG PET). Methods: Drug-naïve AD patients with wandering (n=80) and without wandering (n=262) were recruited. First, the specific pattern of wandering type was operationally classified according to specific wandering score and clinical assessment. Second, brain FDG PET was performed and fluorodeoxyglucose (FDG) uptake differences of specific brain regions according to wandering patterns were compared to those of non-wanderers. Results: In patients with pacing pattern, FDG PET showed significant lower FDG uptake in both middle cingulum and left putamen cluster compared to non-wanderers. The right precuneus and supplementary motor area in patients with random pattern and left calcarine sulcus, right calcarine sulcus, right middle cingulum, and right post central gyrus in patients with lapping pattern had significantly lower FDG uptake compared to non-wanderers. Conclusions: This study showed that wandering in patients with AD had three distinct patterns. These specific patterns showed significant lower FDG uptake in specific brain areas compared to non-wanderers.

• Journal of Astronomy and Space Sciences
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• 제36권3호
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• pp.115-119
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• 2019

This paper is a part of the series on positron annihilation spectroscopy of two-phase diffuse gas-and-dust aggregates, such as interstellar medium and the young remnants of type II supernovae. The results obtained from prior studies were applied here to detect the relationship between the processes of the annihilation of the K-shell electrons and incident positrons, and the effects of these processes on the optical spectra of their respective atoms. Particular attention was paid to the Doppler broadening of their optical lines. The relationship between the atomic mass of the elements and the Doppler broadening, ${\Delta}{\lambda}_D$ (${\AA}$), of their emission lines as produced in these processes was established. This relationship is also illustrated for isotope sets of light elements, namely $^3_2He$, $^6_3Li$, $^7_3Be$, $^{10}_5B$ and $^{11}_5B$. A direct correlation between the ${\gamma}-line$ luminosity ( $E_{\gamma}=1.022MeV$) and ${\Delta}{\lambda}_D$ (${\AA}$) was proved virtually. Qualitative estimates of the structure of such lines depending on the positron velocity distribution function, f(E), were made. The results are presented in tabular form and can be used to set up the objectives of further studies on active galactic nuclei and young remnants of type II supernovae.

• Journal of Astronomy and Space Sciences
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• 제38권1호
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• pp.55-63
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• 2021

The universe is well known to be consists of dark energy, dark matter and the standard model (SM) particles. The dark matter dominates the density of matter in the universe. The dark matter is thought to be linked with dark photon which are hypothetical hidden sector particles similar to photons in electromagnetism but potentially proposed as force carriers. Due to the extremely small cross-section of dark matter, a large amount of data is needed to be processed. Therefore, we need to optimize the central processing unit (CPU) time. In this work, using MadGraph5 as a simulation tool kit, we examined the CPU time, and cross-section of dark matter at the electron-positron collider considering three parameters including the center of mass energy, dark photon mass, and coupling constant. The signal process pertained to a dark photon, which couples only to heavy leptons. We only dealt with the case of dark photon decaying into two muons. We used the simplified model which covers dark matter particles and dark photon particles as well as the SM particles. To compare the CPU time of simulation, one or more cores of the KISTI-5 supercomputer of Nurion Knights Landing and Skylake and a local Linux machine were used. Our results can help optimize high-energy physics software through high-performance computing and enable the users to incorporate parallel processing.

• Korean Journal of Radiology
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• 제1권1호
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• pp.51-55
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• 2000

Objective: To determine the accuracy of CT and positron emission tomography (PET) in the diagnosis of recurrent uterine cervical cancer. Materials and Methods: Imaging findings of CT and PET in 36 patients (mean age, 53 years) in whom recurrent uterine cervical cancer was suspected were analyzed retrospectively. Between October 1997 and May 1998, they had undergone surgery and/or radiation therapy. Tumor recurrence was confirmed by pathologic examination or follow-up studies. Results: In detecting recurrent uterine cervical cancer, the sensitivity, specificity, and accuracy of CT were 77.8%, 83.3%, and 80.5%, respectively, while for PET, the corresponding figures were 100%, 94.4%, and 97.2%. The Chi-square test revealed no significant difference in specificity (p = .2888), but significant differences in sensitivity (p = .0339) and accuracy (p = .0244). Conclusion: PET proved to be a reliable screening method for detecting recurrent uterine cervical cancer, but to determine the anatomical localization of recurrent tumors, and thus decide an adequate treatment plan, CT was eventually needed.

• 한국진공학회지
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• 제17권2호
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• pp.160-164
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• 2008

저속 에너지 도플러 넓어짐 양전자 소멸 분광법으로 $MgB_2$ 박막내의 원자 크기 정도 고체 구조 특성에 대하여 조사하였다. 양전자와 전자의 쌍소멸로 발생하는 511keV 감마선 스펙트럼의 수리적 해석 방법인 S-변수를 사용하여, 상전이 근처 온도에서 박막의 구조 변화를 측정하였다. 비등방성 구조로 된 $MgB_2$ 박막에서 초전도 특성을 갖는 상전이 온도 근처에서 S-변수를 측정하였다. 양전자의 입사 에너지 10keV에서 측정된 S-변수의 최고치는 박막의 온도가 30K에서 0.567이고, 50 K에서는 0.570로 큰 변화는 없었다. 이 결과로부터 양전자가 Boron 층의 초 전자와 소멸하기 보다는 Mg층 근처의 상 전자와 소멸하는 것으로 판단된다. $MgB_2$의 박막의 외층은 Mg층으로 이루어졌다고 할 수 있다.