• Nuclear Engineering and Technology
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• 제38권6호
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• pp.489-504
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• 2006

A review has been made for the previous studies on safety of a geologic repository for high-level radioactive wastes (HLW) related to autocatalytic criticality phenomena with positive reactivity feedback. Neutronic studies on geometric and materials configuration consisting of rock, water and thermally fissile materials and the radionuclide migration and accumulation studies were performed previously for the Yucca Mountain Repository and a hypothetical water-saturated repository for vitrified HLW. In either case, it was concluded that it would be highly unlikely for an autocatalytic criticality event to happen at a geologic repository. Remaining scenarios can be avoided by careful selection of a repository site, engineered-barrier design and conditioning of solidified HLW. Thus, criticality safety should be properly addressed in regulations and site selection criteria. The models developed for radiological safety assessment to obtain conservatively overestimated exposure dose rates to the public may not be used directly for the criticality safety assessment, where accumulated fissile materials mass needs to be conservatively overestimated. The models for criticality safety also require more careful treatment of geometry and heterogeneity in transport paths because a minimum critical mass is sensitive to geometry of fissile materials accumulation.

• 대한핵의학회지
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• 제25권2호
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• pp.186-191
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• 1991

Radionuclide cardiac studies lend themselves exceptionally well to functional imaging. This is especially true for gated blood pool scan (GBP). Making functional images is also possible in radionuclide angiocardiography (RNAC). In this study we tried to validate the functional images obtained from RNAC by comparing it with GBP. Twenty three patients (16 patients with coronary artery diseases, 5 with hypertensive heart diseases, and 2 with nonspecific chest pains) underwent simultaneous RNAC and GBP at the same position (LAO $45^{\circ}$). From both studies, global ejection fraction, regional ejection fraction, phase image, amplitude image, stroke image, paradox image, maximum ejection and maximum filling rates were obtained. Global ejection fraction are almost same in both studies. Regional ejection fractions of apex and inferior portion of left ventricle calculated from RNAC are well correlated with those of GBP. Phase and paradox image, maximum ejection and maximum filling rates were obtained. Global ejection fraction are almost same in both studies. Regional ejection fractions of apex and inferior portion of left ventricle calculated from RNAC are well correlated with those of GBP. Phase and paradox images of RNAC are very similar to those of GBP. However, amplitude and stroke images are different. Regional ejection fractions of the left ventricular base, maximum ejection and maximum filling rates obtained from RNAC are significantly different from those of GBP. In conclusion, albeit all of functional images of RNAC is not same as GBP, regional walt motions and global left ventricular function are expected to be successfully analyzed by phase and paradox image and ejection fraction.

• 해양환경안전학회지
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• 제27권5호
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• pp.618-629
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• 2021

2011년 동일본대지진에 의해 발생한 후쿠시마 원자력 발전소 사고와 최근 국내 지진 발생 빈도의 증가는 원자력 발전소의 지진 안전성에 대한 불안감을 야기하였다. 더불어 최근(2021년) 일본 동경전력은 후쿠시마 원전 오염수의 태평양 방류를 결정하였으며, 이로 인해 국내외 수산물을 통한 방사능 오염 가능성이 높아지면서 국민들의 우려가 급증하고 있다. 후쿠시마 원전사고 이후 해양으로의 인공방사능 유입에 관한 연구는 국제적으로 많이 이루어졌으나, 한국인의 주요 식재료인 동아시아 연근해의 수산물에서 인공방사능의 분포 현황 및 축적에 대한 연구는 상대적으로 부족한 실정이다. 따라서 이 논문에서는 후쿠시마 원전사고 이후, 국내산 수산물에서의 원전 기원 인공방사능(예, ¹³⁷Cs, ^239+240Pu, ⁹⁰Sr 등)의 분포 특성과 관련한 최근 연구 사례들을 소개하고자 한다. 또한, 후쿠시마 원전오염수의 방류와 더불어 2030년까지 계획된 중국의 신규 원전 시설로 인한 향후 한반도 주변해역의 방사능 유출 영향에 대한 대비 및 사전 연구가 필요한 시점이기에 향후 연구 방향들을 제안하고자 한다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.1109-1110
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• 2004

• Nuclear Medicine and Molecular Imaging
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• 제40권4호
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• pp.200-204
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• 2006

목적: 산소포화도법과 비교하여 동위원소법을 이용한 Qp/Qs측정의 정확도를 알아보고, 이와 연관된 요인이 무엇인지, 추적 검사시 두 검사법의 결과를 서로 비교해서 사용할 수 있는지에 대하여 알아보고자 하였다. 대상 및 방법: 두 검사법으로 Qp/Qs를 측정한 207명의 환자를 대상으로 하였다. 동위원소를 이용한 방법은 폐에 관심영역을 설정하여 시간-방사능 곡선을 얻어서 gamma variate model에 적용하여 면적으로부터 Qp/Qs를 구하였다. 환자의 연령, 좌우 단락의 종류와 동반된 질환 등에 따라서 방사성 동위원소 조영술과 심도자술로 얻어진 Qp/Qs의 상관계수와 일치도를 분석하였다. 결과: 동위원소 검사법과 심도자술로 얻어진 Qp/Qs의 평균치는 각각 $1.85{\pm}0.50,\;1.74{\pm}0.51$이며, 두 검사법으로 얻은 Qp/Qs의 상관계수는 0.86 (p<0.001)으로 강한 상관관계를 보였다. Bland-Altman 분석에서 두 검사법에 의한 Qp/Qs의 일치의 한계값은 $-0.42{\sim}0.63$, 범위는 1.05였다. 심실중격 결손증 환자에서는 상관계수가 0.90으로 강한 상관관계를 보였으며, 일치의 한계값은 $-0.29{\sim}0.45$ 였다. 심방중격 결손증, 심실중격 결손증, 동맥관 개존증 환자와 삼첨판 부전증과 승모판 부전증이 동반된 환자에서의 상관계수는 각각 0.78, 0.90, 0.84, 0.63, 0.44 였으며, 일치의 범위는 1.52, 0.74, 0.96, 1.57. 1.50이였다. 결론: 동위원소 검사법과 심도자술로 얻어진 Qp/Qs는 전체적으로 좋은 상관관계를 보이나 일치의 한계값이 크므로 추적 검사시 서로 호환하여 사용하기 어렵다. 방실판막 부전증이 동반된 경우에는 낮은 상관관계와 낮은 일치도를 보였다.

• Journal of Chest Surgery
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• 제19권1호
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• pp.25-34
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• 1986

Recently, radionuclide angiocardiogram is one of the most common procedure for assessment of ventricular performance due to its distinctive advantages such as safety, accuracy, and ease of repeated studies. Also, measurement and comparison between pre and postoperative left ventricular ejection fraction [LVEF] are meaningful for assessing the severity of myocardial damage which occurred during open heart surgery and the status of myocardial recovery. We obtained pre and post operative LVEF using radionuclide angiocardiogram on 30 patients composed of atrial septal defect, ventricular septal defect, cyanotic congenital heart disease, and valvular heart disease who undergone the open heart surgery from March to august 1984. The study revealed that ventricular septal defect and mitral valvular heart disease showed 8.1% and 6.2% decreases of postoperative LVEF, respectively. But, there are little increases of postoperative LVEF in the atrial septal defect and cyanotic congenital heart disease. In ventricular septal defect, each group of Qp/Qs over 2.0 and systolic pulmonary artery pressure over 50mmHg showed significant 17% and 14.7% decreases of postoperative LVEF, respectively. Considering the duration of the aortic cross clamping times and closing methods of VSD, each group of duration over 30 min. and of patch closure showed 13.9% and 14.2% decreases of LVEF between pre and postoperative status respectively which was significant finding statistically.

• 대한핵의학회지
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• 제32권3호
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• pp.211-224
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• 1998

The role of scintigraphic imaging has moved from the detection of lesions to the tissue-specific characterization of lesions over the past 2 decades. Major advances in nuclear medicine imaging include: 1) positron imaging, 2) improved instrumentation, such as the use of multidetector (dual or triple head) gamma cameras for single photon emission computed tomography, and 3) development of numerous new radiopharmaceuticals for positron or single photon imaging (labeled glucose analogue, amino acids, fatty acids, hormones, drugs, receptor ligands, monoclonal antibodies, etc). These advances have resulted in a significantly improved efficacy of radionuclide techniques for the evaluation of various tumors, including those within the liver. The current role of nuclear medicine in the evaluation of focal hepatic tumors is reviewed in this article with an emphasis on the clinical applications of various tracer studies and imaging findings.

• 대한핵의학회지
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• 제29권1호
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• pp.61-72
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• 1995

The author performed radionuclide esophageal transit studies(RETS) with liquid and solid boluses using the same day protocol in 90 normal controls and 164 patients with various primary esophageal motility disorders who were diagnosed by manometric criteria and clinical courses. The authors calculated mean esophageal transit time(MTT) and mean residual retention(MRR) in each of the liquid and solid studies, and classified time-activity curve(TAC) patterns. The normal criteria of RETS with liquid bolus were MTT<24 sec, MRR<9%, and the TAC pattern that showed rapid declining slope and flat low residual(Type 1). The normal criteria of RETS with solid bolus were MTT<35 sec, MRR<9% and TAC of type 1. With these normal criteria, the sensitivity and the specificity of the liquid study were 62.2 % and 97.8%, respectively. The sensitivity increased to 75.4% with the solid study. The author also found that the RETS was highly reproducible. The achalasia typically showed no effective emptying of both liquid and solid boluses during the whole study period, and was well differentiated by its extremely long transit time and high retention from the other motility disorders. The diffuse esophageal spasm (DES) and nonspecific esophageal motility disorder(NEMD) showed intermediate delay in transit time and increased retention. In the groups of hypertensive lower esophageal sphincter(LES), hypotensive LES and nutcracker, there noted no significant difference with the normal control group in terms of MTT and MRR. The DES and NEMD could be more easily identified by solid studies that showed more marked delay in MTT and increased MRR as compared with the liquid study. In conclusion, esophageal scintigraphy is a safe, noninvasive and physiologic method for the evaluation of esophageal emptying.

• 대한핵의학회지
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• 제21권2호
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• pp.183-190
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• 1987

In Raynaud's phenomenon, the authors measured finger blood flow after ice water exposure by analyzing the time activity curve of radionuclide angiography on both hands. The results were as follows: 1) The digital blood flow did not decrease after ice water exposure in normal subjects. 2) In the patients with Raynaud's phenomenon, there were two groups: the one had decreased digital blood flow after cold exposure, and the other had paradoxically increased digital blood flow after cold exposure. 3) There was no difference in the digital blood flow of hand in room temperature between the normal and the patients with reduced digital blood flow after cold exposure, but the digital blood flow of the hand in room temperature was markedly reduced in the patients with paradoxically increased flow after cold exposure. 4) In the static image the difference was not significant in comparision with the dynamic study, because it represents pooling of the blood in the vein rather than flow. 5) After the treatment with nifedipine, the digital blood flow increased. In conclusion, the radionuclide angiography was useful in measuring the digital blood flow in Raynaud's phenomenon, and further studies with various drugs is expected.

• 대한핵의학회지
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• 제29권1호
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• pp.15-21
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• 1995

To evaluate availability of cerebral radionuclide imaging for diagnosis of brain death, we examined 25 patients with a suspected clinical diagnosis of brain death. 8 patients were studied by $^{99m}Tc$ DTPA and 15 patients were studied by $^{99m}Tc$ HMPAO (Hexamethyl propyleneamine oxime). Seven patients with $^{99m}Tc$ DTPA studies revealed absence of cerebral blood flow and sagittal sinus activity. All of 15 patients with $^{99m}Tc$ HMPAO studies revealed complete absence of cerebral perfusion. The results of the cerebral radionuclide studies of brain death correlated with other clinical conditions, such as intracranial pressure(ICP), EEG, transcranial doppler sonography(TCDS), and neurologic examination. The ICP of 8 patients, who are confirmed by brain death with $^{99m}Tc$ HMPAO study are elevated in all cases. In conclusion, cerebral radionuclide imaging for diagnosis of brain death is available. $^{99m}Tc$ HMPAO imaging is unequivocal, easily interpreted, well reflect the physiologic state of increased ICP, and provides adequate assessment of posterior fossa activity. In addition, the SPECT imaging with $^{99m}Tc$ HMPAO produces more accurate results due to it's superiority of image contrast and proper localization of radiopharmaceutical distribution than conventional planar imaging.