• 대한방사성의약품학회지
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• 제8권1호
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• pp.39-44
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• 2022

The development of methods for the inert and stable radiohalogenation of targeted radiopharmaceuticals is a prerequisite for real-time diagnosis and therapy using radiohalogenated radiopharmaceuticals. Radiohalogenated carboranes demonstrate superior stability in vivo and versatile applications compared with directly labeled tyrosine analogues or synthetically modified organic compounds. Herein, we focus on the most common approaches for the radioiodination (¹²³l, ¹²⁴l, ¹²⁵l, and ¹³¹l) of carborane derivatives.

• Journal of Radiation Protection and Research
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• 제26권2호
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• pp.93-99
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• 2001

해부학적으로 단순한 수학적인형팬텀의 한계를 극복하기 위한 voxel 머리팬텀을 제작하고 BNCT(Boron Neutron Capture Therapy) 시행 시 선량분포를 계산하였다. 일반목적 몬테칼로 코드인 MCNP4B의 반복구조 알고리즘을 이용하여 voxel 몬테칼로 계산체계를 수립하였고 두 가지 물질로 구성된 예시적 voxel 팬텀과 기하체조합팬텀의 계산값 비교를 통해 계산체계를 검증하였다. 미국 NLM(National Library of Medicine)에서 제공하는 VHP man 인체단층사진에 대한 분할 및 색인작업을 통해 voxel 머리팬텀을 제작하여 AP 및 PA 방향에서 입사하는 넓고 평행한 광자 및 중성자빔에 대한 선량값을 MIRD 팬텀의 계산값과 비교한 결과 중성자빔 AP 방향조사 시 MIRD 팬텀에서는 볼 수 없는 안구로 인한 중성자 감쇠현상을 확인할 수 있었다. 3차원 정밀계산이 필요한 BNCT 시술시 선량분포계산을 위해 뇌 중앙에 직경 5cm의 구형 뇌종양 체적을 정의하고 뇌와 종양의 붕소 함량을 조정하여 10keV 및 40keV 상부입사 중성자에 의한 장기별 흡수선량을 계산한 결과 종양에 $30{\mu}g/g$, 정상세포에 $3{\mu}g/g$의 붕소를 주입한 경우 붕소함량이 없을 때에 비해 2배 가량 큰 선량을 보였다. 본 연구를 통해 voxel몬테칼로기법을 이용한 선량평가체계를 수립하였고 정밀한 선량계산을 필요로 하는 치료방사선분야 선량계산에 실제 인체에 가까운 voxel팬텀의 응용가능성을 제시하였다.

• Nuclear Engineering and Technology
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• 제4권4호
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• pp.340-344
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• 1972

$^{79}$ Br, $^{80}$ Se, $^{103}$ Rh, $^{115}$ In 및 $^{133}$ Cs의 열중성자 포획시 혈성되는 이성체쌍의 비와 $^{79}$ Br, $^{80}$ Se 및 $^{l33}$Cs의 Epi-Cd 중성자 포획시 형성되는 이성체 쌍의 비를 측정하였다. 동 이성체비는 중성자 조사후 ${\gamma}$-선 분광분석법으로 얻은 붕괴곡선을 분석하여 측정하였다. 계측효율곡선은 전체불확실율이 악 1%인 표준선원을 사용하여 결정하였다. $\sigma$ high spin/($\sigma$ high spin+$\sigma$ low spin)으로 나타낸 열중성자로 생성된 $^{80, 80m}$Br, $^{81,81m}$Se, $^{014, 104m}$Rh, $^{116,116m}$In 및 $^{134, 134m}$Cs 쌍들의 이성체비는 각각 0.21$\pm$0.01, 0.14$\pm$0.02, 0.12$\pm$0.02, 0.69$\pm$0.07 및 0.058$\pm$0.004 이었다. Epi-Cd 중성자에 의해서 생성된 $^{80, 80m}$Br, $^{81,81m}$Se, 및 $^{134, 134m}$Cs 쌍의 이성체 비는 각각 0.19$\pm$0.02, 0.29$\pm$0.02 및 0,74$\pm$0,011 이었다. 실험적으로 얻은 본값을 통계적 모델로부터 얻은 이론치와 비교하여 본 결과 일반적인 일치를 보였다.다.

• 지구물리와물리탐사
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• 제22권3호
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• pp.149-159
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• 2019

암석구성성분검층(중성자-감마스펙트로스코피검층)은 중성자선원의 비탄성산란과 중성자포획 작용으로부터 생성되는 감마선을 측정하여 지층의 원위치 광물조성을 추정할 수 있는 기술이다. 일반적으로 지층의 광물조성 평가는 코어에 대한 X선 회절법, X선 형광분석법 등의 실내 시험자료를 주로 이용하고 있으나 이는 조사 구간의 극히 일부분에 대한 결과이며 특히, 유체의 유동 경로 구간은 주로 파쇄대 및 사질층인데 이 구간들의 코어 회수율이 불량하여 조사 구간 전체에 대한 광물조성 평가는 한계가 있다. 따라서 시추공 전 구간에 대한 원위치 광물조성 추정 기술개발은 지중환경 평가에 중요한 역할을 할 수 있다. 이 기술은 전통, 비전통 저류층 평가를 중심으로 최근까지 장비 개발 및 관련 연구가 활발히 진행되고 있는 분야이지만 몇 개 서비스회사의 독점기술로 자세한 정보 미공개, 다양한 지층 및 인공모형을 이용한 화학-광물학 데이터베이스 구축 문제 등으로 국내 연구에 직접적으로 적용하기에는 어려움이 있었다. 이 해설논문에서는 암석구성성분검층의 기본원리, 시스템 구성, 교정시설, 국외 기 개발된 검층시스템 분석 및 연구개발 동향 등을 통해 해당 기술을 소개하고, 국내 시스템 제작을 위한 기술 적용 방안을 검토하였다.

• 대한화학회지
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• 제19권5호
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• pp.331-338
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• 1975

크롬산염, 중크롬산염, 요오드산염 및 과요드산염의 중성자포획에 수반하는 크롬-51 및 요오드-128 반조 화학종의 분배를 거름종이 전기영동법으로 검토하였다. 유효반조에너지 및 내부전환의 관점에서 생각하면 중성자 포획원자가 초기분자중에 잔유하고 반조원자에너지가 결정의 적은 범위를 가열하며 소멸된다고 하기 어렵다. 그러나 거름종이 전기영동결과 더 많은 크롬-51 및 요오드-128 반조원자가 어미분자와 결합되어 있음을 알 수 있었다. 잔류율의 관찰결과 반응 이론을 Disorder Model로 설명하였다. 양이온 반경이 클수록 2차 cage를 돌파하는 반조원자의 확율이 높다. 암모늄염중 암모늄이온은 disorder zone에서 환원작용을 하며 잔류율이 낮어졌다. 결정구조에서 자유공간이 크면 잔류율이 낮어졌다.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.145-152
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• 2021

Purpose: During the treatments of cancer patients with a linear accelerator (LINAC) using photon beams with energies ≥8 MV, the components inside the LINAC head get activated through the interaction of photonuclear reaction (γ, n) and neutron capture (n, γ). We used spectroscopy and measured the dose rate for the LINAC in operation after the treatment ended. Methods: We performed spectroscopy and dose rate measurements for three units of LINACs with a portable high-purity Germanium (HPGe) detector and a survey meter. The spectra were obtained after the beams were turned off. Spectroscopy was conducted for 3,600 seconds, and the dose rate was measured three times. We identified the radionuclides for each LINAC. Results: According to gamma spectroscopy results, most of the nuclides were short-lived radionuclides with half-lives of 100 days, except for ⁶⁰Co, ⁶⁵Zn, and ¹⁸¹W nuclides. The dose rate for three LINACs obtained immediately in front of the crosshair was in the range of 0.113 to 0.129 µSv/h. The maximum and minimum dose rates measured on weekends were 0.097 µSv/h and 0.092 µSv/h, respectively. Compared with the differences in weekday data, there was no significant difference between the data measured on Saturday and Sunday. Conclusions: Most of the detected radionuclides had half-lives <100 days, and the dose rate decreased rapidly. For equipment that primarily used energies ≤10 MV, when the equipment was transferred after at least 10 minutes after shutting it down, it is expected that there will be little effect on the workers' exposure.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.328-332
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• 2016

Background: Boron Neutron Capture Therapy (BNCT) is a new radiation therapy. In BNCT, there exists some very critical problems that should be solved. One of the severest problems is that the treatment effect cannot be known during BNCT in real time. We are now developing a SPECT (single photon emission computed tomography) system (BNCT-SPECT), with a cadmium telluride (CdTe) semiconductor detector. BNCT-SPECT can obtain the BNCT treatment effect by measuring 478 keV gamma-rays emitted from the excited state of $^7Li$ nucleus created by $^{10}B(n,{\alpha})$ $^7Li$ reaction. In the previous studies, we investigated the feasibility of the BNCT-SPECT system. As a result, the S/N ratio did not meet the criterion of S/N > 1 because deterioration of the S/N ratio occurred caused by the influence of Compton scattering especially due to capture gamma-rays of hydrogen. Materials and Methods: We thus produced an arrayed detector with two CdTe crystals to test cross talk phenomenon and to examine an anti-coincidence detection possibility. For more precise analysis for the anti-coincidence detection, we designed and made a collimator having a similar performance to the real BNCT-SPECT. Results and Discussion: We carried out experiments with the collimator to examine the effect of cross talk of scattering gamma-rays between CdTe elements more practically. As a result of measurement the coincidence events were successfully extracted. Conclusion: We are now planning to carry out evaluation of coincidence rate from the measurement and comparison of it with the numerical calculations.

• Nuclear Engineering and Technology
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• 제31권4호
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• pp.391-400
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• 1999

A conceptual core design of the 1,300MWe KNGR (Korean Next Generation Reactor) without using soluble boron for reactivity control was developed to determine whether it is technically feasible to implement SBF (Soluble Boron Free) operation. Based on the borated KNGR core design, the fuel assembly and control rod configuration were modified for extensive use of burnable poison rods and control rods. A new fuel rod, in which Pu-238 had been substituted for a small amount of U-238 in fuel composition, was introduced to assist the reactivity control by burnable poison rods. Since Pu-238 has a considerably large thermal neutron capture cross section, the new fuel assembly showed good reactivity suppression capability throughout the entire cycle turnup, especially at BOC (Beginning of Cycle). Moreover, relatively uniform control of power distribution was possible since the new fuel assemblies were loaded throughout the core. In this study, core excess reactivity was limited to 2.0 %$\delta$$\rho$ for the minimal use of control rods. The analysis results of the SBF KNGR core showed that axial power distribution control can be achieved by using the simplest zoning scheme of the fuel assembly Furthermore, the sufficient shutdown margin and the stability against axial xenon oscillations were secured in this SBF core. It is, therefore, concluded that a SBF operation is technically feasible for a large sized LWR (Light Water Reactor).

• 천문학회보
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• 제35권2호
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• pp.72.2-72.2
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• 2010

The extremely metal-poor halo planetary nebula BoBn 1 has been investigated based on IUE archive data, Subaru/HDS spectra, VLT/UVES archive data, and Spitzer/IRS spectra. We have measured a heliocentric radial velocity of $+191.6\pm1.3\;kms^{-1}$ and expansion velocity 2Vexp of $40.5\pm3.3\;kms^{-1}$ from an average over 300 lines. The estimations of C, N, O, and Ne abundances from the optical recombination lines (ORLs) and Kr, Xe, and Ba from the collisional excitation lines (CELs) are also done. We have detected 5 fluorine and several slow neutron capture elements (the s-process). The amounts of [F/H], [Kr/H], and [Xe/H] suggest that BoBn 1 is the most F-rich among F detected PNe and is a heavy s-process element rich PN. The photo-ionization models built with non-LTE theoretical stellar atmospheres indicate that the progenitor was a 1-1.5 $M_\bigstar$ that would evolve into a white dwarf with an $0.62M_{\odot}$ core mass and $0.09M_{\odot}$ ionized nebula. Careful examination implies that BoBn 1 has evolved from a binary and experienced coalescence during the evolution to become a visible PN. The elemental abundances except N could be explained by a binary model composed of $0.75M_{\odot}+1.5M_{\odot}$ stars.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1051-1054
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• 2013

Closo-carborane has been considered as an efficient boron-carrier for boron neutron capture therapy (BNCT) and an attractive surrogate of lipophilic phenyl or cyclohexyl ring in drug design. Despite a great number of carborane-containing ligands have been synthesized and evaluated, molecular modeling studies of carborane ligands with macromolecules have been rarely reported. We herein describe a facile docking and scoring-function strategy of 16 carborane ligands with an estrogen receptor by using the commercial Gaussian, Chem3D Pro and Discovery Studio (DS) computational programs. Docked poses of the carborane ligands in silico exhibited similar binding modes to that of the crystal ligand in the active site of estrogen receptor. Score analysis of the best docked pose for each ligand indicated that the Ligscore1 and the Dockscore have a moderate correlation with in vitro biological activity. This is the first report on the scoring-correlation studies of carborane ligands with macromolecules. The integrated Gaussian-DS approach has a potential application for virtual screening, De novo design, and optimization of carborane ligands in medicinal chemistry.