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RISS 인기검색어
- 검색키워드
- 저자 : 정현태(Hyun-Tai Jung) (검색결과 6 건)
- 무료
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Monte Carlo Simulation of the Carbon Beam Nozzle for the Biomedical Research Facility in RAON
배재범,조병철,곽정원,박우윤,임영경,정현태,Bae, Jae-Beom,Cho, Byung-Cheol,Kwak, Jung-Won,Park, Woo-Yoon,Lim, Young-Kyung,Chung, Hyun-Tai Korean Society of Medical Physics 2015 의학물리 Vol.26 No.1
본 연구에서 한국형 중이온 가속기 RAON에서의 의생물 실험을 위하여 요구되는 빔 조건을 만족할 수 있도록 Monte Carlo 전산모사를 통한 노즐 설계를 최적화하고자 하였다. 의생명 실험을 위한 빔 조건으로 최대 조사면 크기, 선량균일도 그리고 빔 오염도의 특정 조건을 만족하는 $C^{12}$ 빔 생산이 요구되었다. 이때 최적화된 빔 노즐 설계를 위하여 Monte Carlo 시뮬레이션인 GEANT4 toolkit이 사용되었다. $15{\times}15cm^2$ 이상의 빔 조사면 크기와 3% 이내의 선량 균일도 그리고 전체 선량의 5% 보다 낮은 빔 오염도를 기본적인 조건으로 설정 되었다. 조사면 크기는 쌍극자 자석에 의해서 빔의 각도를 기울여 원형으로 회전하면서 쌍극자 자석의 아래쪽에 위치한 산란판의 두께를 조정하여 최적화 하였다. 빔 스캐닝 각도와 산란판의 두께는 Monte Carlo 시뮬레이션 분석에 의해서 각각 $0.5^{\circ}$와 0.05 cm로 최적의 값을 나타내었다. 선량 균일도와 최대 조사면 크기를 만족하기 위하여 static과 scanning beam을 복합하는 기술을 이용한 새로운 빔 전달 방법을 소개하였다. 중앙 고정용 빔과 빔 축으로부터 $0.5^{\circ}$ 경사각을 가지고 회전하는 빔과 경사각이 없이 바로 들어오는 빔을 조합하여 선량균일도가 1.1%와 빔 조사면의 최대크기가 $15{\times}15cm^2$가 되는 것을 확인하였다. 빔 오염도는 $C^{12}$ 이온과 다른 입자들에 의해서 전달된 흡수선량의 비율로 나타내었다. 물등가 깊이(water equivalent depth) 5 cm에서 17 cm 사이에서의 빔 오염도는 전체 선량에서의 2.5% 미만임을 확인하였으며 이와 같은 결과를 바탕으로, 본 연구에서는 의생명 실험을 위하여 요구되는 빔 조건을 만족하는 노즐 구조를 설정할 수 있었다. The purpose of the Monte Carlo simulation study was to provide the optimized nozzle design to satisfy the beam conditions for biomedical researches in the Korean heavy-ion accelerator, RAON. The nozzle design was required to produce $C^{12}$ beam satisfying the three conditions; the maximum field size, the dose uniformity and the beam contamination. We employed the GEANT4 toolkit in Monte Carlo simulation to optimize the nozzle design. The beams for biomedical researches were required that the maximum field size should be more than $15{\times}15cm^2$, the dose uniformity was to be less than 3% and the level of beam contamination due to the scattered radiation from collimation systems was less than 5% of total dose. For the field size, we optimized the tilting angle of the circularly rotating beam controlled by a pair of dipole magnets at the most upstream of the user beam line unit and the thickness of the scatter plate located downstream of the dipole magnets. The values of beam scanning angle and the thickness of the scatter plate could be successfully optimized to be $0.5^{\circ}$ and 0.05 cm via this Monte Carlo simulation analysis. For the dose uniformity and the beam contamination, we introduced the new beam configuration technique by the combination of scanning and static beams. With the combination of a central static beam and a circularly rotating beam with the tilting angle of $0.5^{\circ}$ to beam axis, the dose uniformity could be established to be 1.1% in $15{\times}15cm^2$ sized maximum field. For the beam contamination, it was determined by the ratio of the absorbed doses delivered by $C^{12}$ ion and other particles. The level of the beam contamination could be achieved to be less than 2.5% of total dose in the region from 5 cm to 17 cm water equivalent depth in the combined beam configuration. Based on the results, we could establish the optimized nozzle design satisfying the beam conditions which were required for biomedical researches.
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임상 : 비기능성 뇌하수체 선종의 감마나이프 치료 성적 -단일 기관의 조기 결과 보고-
이승준 ( Seung Joon Lee ),김용휘 ( Yong Hwy Kim ),정현태 ( Hyun Tai Chung ),백선하 ( Sun Ha Paek ),정희원 ( Hee Won Jung ),김동규 ( Dong Gyu Kim ) 대한뇌종양학회 2008 대한뇌종양학회지 Vol.7 No.2
Objective:The purpose of this study is to survey the efficacy of gamma knife radiosurgery(GKS) in patients with nonfunctioning pituitary adenomas(NFPAs). Materials and Methods:A total of 32 patients(14 males and 18 females) with NFPAs underwent GKS between 1998 and 2007. Among them, 27 patients(84%) underwent GKS for remnant or recurrent tumors after surgical resection. The median age of the patients was 51 years(range, 21-74). The median follow-up duration was 35 months(range, 12- 120). The median tumor volume was 2.5 cm3(range, 0.7-15.4). The median marginal dose was 15.0 Gy(range, 12.5- 19.0). The median number of shots was 7(range, 4-14). Results:Tumor volume was decreased at the last follow-up in 18 patients(56.2%), and unchanged in 12(37.5%) patients. Fifteen patients experienced tumor shrinkage(46.9%) within 6 months after radiosurgery. Eventually 2 patients experienced tumor growth after radiosurgery. There were neither newly occurred panhypopituitarism nor visual deterioration after GKS. The actuarial tumor control rates were 96.7% and 90.2% at 1 and 3 years, respectively. Conclusion:GKS is safe and effective in treating the patients with NFPAs, especially small remnant tumors after surgical resection which usually have enough distance from the optic apparatus. This is the preliminary result of a single center experience, and more cases with long-term follow-up duration will be necessary to verify the results of the present report.
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이익모,김상진,박순필,정현태,도종웅,주양자 대한신경외과학회 1988 Journal of Korean neurosurgical society Vol.17 No.1
Advances in microneurosurgical treatment of arterial aneurysm have led to increased interest being focused on aneurysm situated within the posterior cerebral fossa. Despite this, reports of neurosurgical intervention in such cases are still rare and there is no report about the distal posterior cerebral artery aneurysm in Korea. An aneurysm of the posterior cerebral artery has been referred to as a "distinct rarity", making up about 0.26 to 2.7% of all cerebral aneurysms. Especially, the incidence of the distal posterior cerebral artery aneurysm is quite rare and most of them are saccular in shape and single in number. The authors report a case of P4 segment aneurysm of left posterior cerebral artery, successfully treated by clipping cross neck and reviewed the literature, and discussed their anatomy, clinical feature, location, and variable operative methods.
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고영관,강재규,정현태,도종웅 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.6
An en bloc bilateral osteotomy of the orbital roofs and frontal sinus for large or deeply situated anterior skull base tumors offers less brain retraction and a wide exposure. The authors describe an en bloc bilateral osteotomy of the orbital roofs and frontal sinus, with skull base reconstruction using inner table of the patient's own frontal bone flap. The approach in this report offers the advantage of wide exposure, one-site operation and short operation time.
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보존적 치료를 받은 뇌지주막하 출혈환자의 장기 추적 조사
최원철,강재규,정현태,도종웅 대한신경외과학회 1994 Journal of Korean neurosurgical society Vol.23 No.7
Two hundreds and our consecutive patients who sustained proven spontaneous subarachnoid hemorrhage with conservative treatment were studied retrospectively. The reasons for conservative treatment were poor condition for surgery, difficulties in surgery and operation refusal. Comparative study was done in proven 47 cases of aneurysmal SAH, 27 cases of SAH with negative angiography and 130 cases of SAH without angiography about age, aneurysm site & size, neurologic grade and mortality & morbidity, etc. Death and occurred in 2 weeks after attack predominantly. Rebleeding was most common cause of mortality(64%, 68/107). Survivals had good quality of life(73%, 19/26).
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