회절 단층촬영 개선에 관한 연구

하은주,황상문,박종욱 원광대학교 공업기술개발연구소 1991 工業技術開發硏究誌 Vol.11 No.-

Abstract Currently computerized tomography is being developed using ultrasound, NMR, microwave, rather than using X-ray. The necessity of using ultrasound is especially increasing for diagnistic image because ultrasound is less hamful than X-ray. This study is simulated with ultrasound for an single cylindrical test object radius 4λ, the refractive index approximately 0.05 and using the new mixed approroxiamtely method. The approxinmatation methed in C.T is a vary important factor in diagnostic image processing. One that I will propose is composed of merits selected of Born and Rytov approximation method. So the new mixed approximation is the one having leas errors than the Born and the Rytov approximation on frequency domain. In this paper, the result of the new mixed approximation method is compared with that of the Born and the Rytov method is shown and the new method gets the good reconstruced object. So the new approximation method can be one of linear approximation methods which is comparable with the Rytov method.

Coronary Artery Disease in Asymptomatic Young Adults: Its Prevalence According to Coronary Artery Disease Risk Stratification and the CT Characteristics

하은주,김유경,정주연,심성신 대한영상의학회 2010 Korean Journal of Radiology Vol.11 No.4

Objective: We aimed at evaluating the prevalence and CT characteristics of occult coronary artery disease (CAD) in young Korean adults under 40 years of age by performing coronary CT angiography (CCTA). Materials and Methods: We retrospectively enrolled 112 consecutive asymptomatic subjects (90 men, mean age: 35.6 ± 3.7 years) who underwent CCTA as part of a general health evaluation. We classified the subjects into three National Cholesterol Education Program risk categories and we assessed the plaque characteristics on CCTA according to the number of involved vessels, the location and type of plaques and vascular remodeling. Results: Twelve individuals had CAD (11%, 11 men). The prevalence of CAD was significantly higher in the subgroups with moderate (22%) or high (25%) risk than that in the low risk subgroup (5%) (p < 0.05). Nine patients had single-vessel disease and three patients had two-vessel disease. The most common location for plaque was the proximal left anterior descending coronary artery (60%). All the patients had non-significant stenosis and plaque, including the non-calcified (27%), mixed (47%) and calcified (27%) types. Positive vascular remodeling was identified in all the patients with non-calcified or mixed plaques. Conclusion: The prevalence of occult CAD was not negligible in the asymptomatic young adults with moderate to high risk, and this suggests the importance of management and risk factor modification in this population. All the patients had non-significant stenosis, and one fourth of the plaques did not show calcification. Objective: We aimed at evaluating the prevalence and CT characteristics of occult coronary artery disease (CAD) in young Korean adults under 40 years of age by performing coronary CT angiography (CCTA). Materials and Methods: We retrospectively enrolled 112 consecutive asymptomatic subjects (90 men, mean age: 35.6 ± 3.7 years) who underwent CCTA as part of a general health evaluation. We classified the subjects into three National Cholesterol Education Program risk categories and we assessed the plaque characteristics on CCTA according to the number of involved vessels, the location and type of plaques and vascular remodeling. Results: Twelve individuals had CAD (11%, 11 men). The prevalence of CAD was significantly higher in the subgroups with moderate (22%) or high (25%) risk than that in the low risk subgroup (5%) (p < 0.05). Nine patients had single-vessel disease and three patients had two-vessel disease. The most common location for plaque was the proximal left anterior descending coronary artery (60%). All the patients had non-significant stenosis and plaque, including the non-calcified (27%), mixed (47%) and calcified (27%) types. Positive vascular remodeling was identified in all the patients with non-calcified or mixed plaques. Conclusion: The prevalence of occult CAD was not negligible in the asymptomatic young adults with moderate to high risk, and this suggests the importance of management and risk factor modification in this population. All the patients had non-significant stenosis, and one fourth of the plaques did not show calcification.

Ultrasonography-Based Thyroidal and Perithyroidal Anatomy and Its Clinical Significance

하은주,백정환,이정현 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.4

Ultrasonography (US)-guided procedures such as ethanol ablation, radiofrequency ablation, laser ablation, selective nerve block, and core needle biopsy have been widely applied in the diagnosis and management of thyroid and neck lesions. For a safe and effective US-guided procedure, knowledge of neck anatomy, particularly that of the nerves, vessels, and other critical structures, is essential. However, most previous reports evaluated neck anatomy based on cadavers, computed tomography, or magnetic resonance imaging rather than US. Therefore, the aim of this article was to elucidate US-based thyroidal and perithyroidal anatomy, as well as its clinical significance in the use of prevention techniques for complications during the US-guided procedures. Knowledge of these areas may be helpful for maximizing the efficacy and minimizing the complications of US-guided procedures for the thyroid and other neck lesions.

Moving-Shot versus Fixed Electrode Techniques for Radiofrequency Ablation: Comparison in an Ex-Vivo Bovine Liver Tissue Model

하은주,백정환,이정현 대한영상의학회 2014 Korean Journal of Radiology Vol.15 No.6

Objective: To compare the ablation characteristics of the moving-shot technique (MST) and the fixed electrode technique (FET) for radiofrequency (RF) ablation in an ex-vivo bovine liver tissue model. Materials and Methods: We performed RF ablation using FET in 110 bovine liver blocks using 11 different ablation times ranging from 5 seconds to 5 minutes (10 blocks per each time duration). Ten bovine liver blocks at each ablation time of 1- or 2-minute, were ablated with MST, which treated conceptual ablation units by moving the electrode tip. We evaluated the ablation volume obtained with FET across ablation time lengths. The results of FET and MST performed with the same ablation time lengths, i.e., 1- and 2-minute ablation time were also compared. Results: The ablation volume achieved with FET gradually increased with increasing ablation time; however, the pair-wise statistical comparison between 2 neighboring ablation time lengths was not significant after 30 seconds. MST with either 1- or 2-minute ablation time achieved larger ablation volumes (1.1 ± 0.2 mL vs. 2.7 ± 0.3 mL, p < 0.001; and 1.4 ± 0.2 mL vs. 5.6 ± 0.4 mL, p < 0.001, respectively), longer true RF times (46.7 ± 4.6 seconds vs. 60 seconds, p < 0.001; and 64.8 ± 4.6 seconds vs. 120 seconds, p < 0.001, respectively), fewer numbers of RF cut-offs (1.6 ± 0.5 vs. 0, p < 0.001; and 5.5 ± 0.5 vs. 0, p < 0.001, respectively), and greater energy deposition (2050.16 ± 209.2 J vs. 2677.76 ± 83.68 J, p < 0.001; and 2970.64 ± 376.56 J vs. 5564.72 ± 5439.2 J, p < 0.001, respectively), than FET. Conclusion: The MST can achieve a larger ablation volume by preventing RF cut-off, compared with the FET in an ex-vivo bovine liver model.

ATM 망의 다중 전송링크상에서 가상경로 동적 대역폭 제어 ( Dynamic Virtual Path Bandwidth Control Over Multiple Transmission Links In an ATM Network )

하은주,도재혁,박종태 한국통신학회 1994 한국통신학회 학술대회논문집 Vol.13 No.1

탄소섬유강화 복합재료 PET-g-PAAm의 합성

하은주,박천욱,이장우 한국고분자학회 1998 한국고분자학회 학술대회 연구논문 초록집 Vol.1998 No.10

Shigella flexneri phage의 加熱非?化에 미치는 Calcium chloride 및 Sodium citrate의 影響

河銀鑄 全南大醫大 1973 전남의대학술지 Vol.10 No.1

Calcium chloride 및 Sodium citrate가 Shigella flexneri phage-宿主菌系에 미치는 影響

河銀鑄 全南大醫大 1973 전남의대학술지 Vol.10 No.1

Purifucation of prtein using Ni-Poly(2-actamido acryic acid)PAAA hydrogel developed for Immobilized Metal Affinity Chromatography(IMAC)

하은주,김유진,이선구,이장우,백현종 한국고분자학회 2007 한국고분자학회 학술대회 연구논문 초록집 Vol.2007 No.4

폐쇄형 토끼 모델에서 심근 경색의 다중검출기전산화단층촬영 (MDCT) 소견: 경색의 시기에 따른 영상 소견과 병리소견간의 연관성

하은주,김유경,이정경 대한영상의학회 2009 대한영상의학회지 Vol.60 No.6

Purpose: This study was designed to evaluate the imaging findings and the diagnostic accuracy for determining the transmural extent of a myocardial infarct (MI) in rabbits with the use of multidetector row CT (MDCT) according to the infarct age, and we determined the radiological and pathological correlation. Materials and Methods: MIs were demonstrated in 10 of 15 rabbits in which ligation of the left coronary arteries was performed. The cardiac scans were obtained according to the infarct age (hyperacute (within 24 hours), acute (24 hours to seven days) or chronic (eight weeks)) by using a 16-MDCT scanner in the contiguous transverse plane with 12×0.75 mm collimation, 420 ms rotation and retrospective ECG-gating. Early and late scans were obtained at one minute and six minutes, respectively, after intravenous contrast injection. The rabbits were sacrificed according to the infarct age. Slices of the cardiac specimens stained with triphenyltetrazolium chloride (TTC) and the MDCT images were evaluated for scoring the transmural extent of the MIs. The agreement of the scores between the MDCT images and TTC-stained specimens was statistically analyzed. The radiological and pathological correlation was determined for the specimens and the MDCT images. Results: The presence of an infarcted myocardium in the hyperacute phase was demonstrated as a mixed low and high-attenuation area on the early and late scans. In the acute phase, a low-attenuation area was seen on the early scan and a low-attenuation area with enhancement along the endocardial and pericardial sides was seen on the late scan. In the chronic phase, a high-attenuation area was seen on the late scan. There was fair agreement for the scores of the MDCT scan in hyperacute MI (kappa value = 0.380) and excellent agreement of the early scan in acute MI and the late scan of chronic MI (kappa value = 0.865 and 0.858, respectively). A pathological examination of the TTC-unstained areas of the MI specimens demonstrated the presence of necrosis of myocardial cells and the increased inflammatory infiltrates and repair process surrounding the damaged myocytes, according to the infarct age. Conclusion: The MDCT findings of MI were various according to the infarct age, which might be caused by the degree of the inflammatory and repair process. For diagnosing the transmural extent of MI, the early MDCT scan was useful for the acute MI and the late scan was useful for the chronic MI. However, MDCT was not useful for diagnosing the transmural extent of the hyperacute MI. 목적: 토끼에서 유발된 심근 경색의 시기별 (다중검출기전산화단층촬영(Multi-detector row CT, 이하 MDCT)) 소견과 전층 침범 진단의 정확도를 평가하고, MDCT와 병리소견 간의 연관성을 알아보고자 하였다. 대상과 방법: 관상동맥을 결찰한 15마리 토끼 중 심근 경색이 발생한 10마리의 토끼에서 시간 경과에 따라 초급성기, 급성기 및 만성기에 조영제를 주입하여 MDCT를 시행하였다. 측정기의 폭 조절(collimation)은 12 × 0.75-mm, 회전 시간은 420 ms로 하고, 후향적 심장 동조화를 시행하였으며, 조영제 주입으로부터 1분과 6분의 초기와 지연기에 심장의 횡단면 영상을 얻었다. MDCT 시행 직후, 토끼를 희생시켜 triphenyltetrazolium chloride (TTC) 염색 표본을 만들고, MDCT와 TTC 표본 간의 심근 경색의 전 층 침범의 일치도를 계산하고, 현미경 검사를 시행하였다. 결과: 심근 경색의 MDCT 소견은 초급성기에는 고음영과 저음영이 섞여 보였고, 급성기에는 초기 영상에서 저음영이, 지연기 영상에서 저음영에 테두리 조영증강이 동반되었으며, 만성기에는 지연기 영상에서 조영증강을 보이는 반흔으로 나타났다. 전 층 침범의 일치도는 초급성기에는 낮았고 (k = 0.380), 급성기의 초기 영상 및 만성기의 지연기 영상에서 높았다 (k = 0.865, 0.858). 현미경 소견에서 초급성기에서 만성기로 갈수록 괴사 심근 주변에 염증반응과 수복반응이 진행되었다. 결론: 심근 경색의 MDCT 소견은 경색의 시간 경과에 따라 다른 양상으로 보이며, 이는 동반되는 염증 및 수복 반응의 정도를 반영하는 것으로 보인다. 또한, 경색 범위의 진단에서, 초급성기에는 MDCT가 유용하지 않고, 급성기에는 초기 영상이, 만성기에는 지연기 영상이 유용하였다.