PASSIVE TYPE POLARIZATION CONVERTER

본 발명은 수동형 편광변환기(passive polarization converter) 및 그를 이용한 편광변환방법에 관한 것이다. 좀 더 구체적으로, 본 발명은 전기광학 폴리머(electro-optic polymer)로 이루어진 광도파로를 이용하여 도파광의 파장에 무관하게 광도파로의 광축방향을 변환시킬 수 있는 수동형 편광변환기 및 그를 이용한 편광변환방법에 관한 것이다. 본 발명의 편광변환기는 3층의 전기광학 폴리머로 이루어진 평면 광도파로(1)의 상하부에 폴링전극(2)이 형성되며, 광도파로(3)의 코어부를 수평 또는 수직방향으로 폴링시키기 위한 편광부(10); 전기한 편광부(10)에 의한 폴링에 의해 형성된 광도파로(3)의 광축방향을 직각방향으로 회전시키기 위한 편광회전부(20); 및, 전기한 편광부(10)에서 폴링된 광도파로(3)의 광축방향과 직각방향으로 광도파로(3)를 폴링시키기 위한 분석부(30)로 구성된다. 본 발명의 수동형 편광변환기는 도파광의 파장에 무관하게 편광변환을 일으킬 수 있고 도파광의 산란현상이 발생되지 않는다는 효과를 지니고 있으며, 본 발명의 편광변환방법에 의해 도파광의 산란발생없이 도파관의 파장에 무관하게 간단하면서도 효율적으로 편광변환시킬 수 있다

성장호르몬 분비 뇌하수체 거대선종 환자에서 경접형골경유 뇌하수체 종양제거술 이후 해면정맥동내 잔존하는 종양에 대한 감마나이프 방사선수술후의 내분비학적 변화에 대한 고찰

Dept. of Medicine/석사OBJECTIVE: To determine long-term effect of gamma knife radiosurgery (GKS) for the treatment of remnant tumor in the cavernous sinus (CS) after transsphenoidal surgery (TSS) of growth hormone (GH)-secreting pituitary macroadenoma.METHODS: Seventeen patients who failed to achieve biochemical remission after TSS were followed for a mean period of 70.2 months (range 17-180) after GKS. All patients underwent regular hormonal examination including serum GH, IGF-1, oral glucose tolerance test, and combined pituitary function test(CPFT). Magnetic resonance imaging was performed 1-year after GKS and then subsequent 1.5-year interval. All patient had remnant tumor only in the CS and received hormone-suppressive medication, sandostatin LAR before or after GKS.RESULTS: There were 13 women and 4 men with a mean age of 41.8 years (range 27-62). 10 patients (58.8%) achieved hormonal remission with a mean time of 47 month (median 40, range 18-129) after GKS and mean marginal radiation dose was 27.9 Gy (range 14-35). Mean tumor volume decreased from 5.15ml (pre-GKS) to 3.55ml (last follow-up) (P <0.001). Actuarial rate of remission at 2,4, and 6 years were 12.5 %, 40%, and 64%, respectively. Intergroup comparison between remission and non-remission group those who had a minimum hormonal follow-up period of 48 months, showed both ‘serum level of GH’ and ‘degree of decreased GH percentile’ at 12 months after GKS showed significant difference (P=0.023), (P=0.014), respectively. A new pituitary hormone deficiency that has significant difference was found only in gonadal axis (P = 0.032) based on last follow-up CPFT. A radiation necrosis was detected in 4 patients.CONCLUSION: GKS in remnant tumor only in the CS after maximal resection of tumor in sellar and suprasellar area is effective especially for minimizing newly developed post-GKS hypopituitarism. However care should be done about radiation induced adjacent parenchymal necrosis after GKS in the CS especially.prohibitio

POLARIZATION INDEPENDENT OPTICAL MODULATOR USING ELECTRO OPTICAL POLYMER WAVEGUIDE

본 발명은 전기광학 플러머를 이용한, 광측이 엇갈린 광도파로 편광변환기와 통상의 위상변조기를 함께 집적한 편광-비의존 광변조기에 관한 것으로서, 입력광의 편광상태를 조절하지 않고도 광신호의 세기를 변조시킬 수 있는 편광-비의존 광변조기에 관한 것으로서, 입력광의 편광상태를 조절하지 않고도 광신호의 세기를 변조시킬 수 있는 편광-비의존 광변조기 전기광학 폴리머를 이용하여 구현한 것이다. 본 발명에 따른 편광-비의존 광변조기는 전기 폴리머를 사용하여 제작한 광축이 엇갈린 편광변환기와 통상의 위상변조기를 마흐-젠더형 광도파로 형태로 집적한 것이다. 입사된 광신호는 두 경로로 갈라져 한쪽은 편광변환기만 통과하여 편광변환되고, 다른 쪽은 위상변조기와 편광변환기를 모두 통과하여 위상변조 및 편광변환된다. 변조된 광신호는 최종적으로 다시 합쳐져 보강간섭 또는 상쇄간섭되어, 결과적으로 편광에 무관한 광변조가 달성된다

ELECTRODE STRUCTURE OF ELECTRO-OPTICAL HIGH POLYMER WAVEGUIDE ELEMENT

본 발명은 전기광학 고분자 광도파로 소자(electro-optic polymer waveguide devices)의 전극 구조에 관한 것이다. 좀 더 구체적으로, 전기광학 고분자 광도파로 소자에서 전기광학 효과를 인가하기 위해 필수적인 폴링(poling)을 완전히 수평방향으로 하고 또한 전기광학 변조를 위한 전계를 수평방향으로 인가하기 위한 전극 구조에 관한 것이다. 본 발명은 전기광학 고분자로 이루어진 코아(core)층, 선형 고분자로 이루어지며 코아층의 상하부에 위치하는 상부 클래딩(cladding)층 및 하부 클래딩(cladding)층, 클래딩층의 외부에 설치되며 코아층에 수평전계를 인가하기 위한 상부 전극 및 하부 전극으로 구성되며, 전기한 구성에 의해 폴링 만으로 삼차원 광도파로를 만들어서 광파의 분극에 대한 소멸비(polarization extinction ratio)가 큰 TE 통과 분극 여과기(TE-pass polarization filter)를 얻을 수 있으며, 광도파로의 코아(core) 부분에서 전계의 방향을 완전히 수평방향으로 만들어 줄 수 있으므로 수평방향 분극 광파의 변조 효율이 향상되어 TE모드(TE-mode)를 효율적으로 전기광학 변조시킬 수 있는 변조 전극으로도 이용될 수 있으며 이 경우에 전계와 광파의 중첩(overlap integral)을 극대화시킴으로써 변조 효율을 향상시킬 수 잇는 효과가 있다

Sudden asystole due to trigeminocardiac reflex during transsphenoidal surgery for pituitary tumor

BACKGROUND: A sudden attack of an asystolic phenomenon is an extremely rare event during transsphenoidal surgery (TSS). It may be caused by an extreme type of trigeminocardiac reflex (TCR) during the manipulation of the trigeminal nerve or its innervated structures. CASE DESCRIPTION: We report two cases of sudden asystole and a case of severe bradycardia due to TCR during TSS. All patients were managed successfully by cessation of the surgical manipulation or with the injection of an anticholinergic agent. CONCLUSIONS: Although TCR occurs rarely and usually is self-limiting, surgeons should be cautious of its occurrence, especially when manipulating the cavernous sinus during TSS. This allows the early detection and appropriate treatment of this manifestation. Stopping the surgical procedure as soon as TCR occurs is likely to normalize the vital parameters. In addition, if further manipulations are inevitable, the administration of anticholinergic medication should be considered cautiously to improve surgical outcomes.ope

Application of low-field intraoperative magnetic resonance imaging in transsphenoidal surgery for pituitary adenomas: technical points to improve the visibility of the tumor resection margin

BACKGROUND: Intraoperative magnetic resonance imaging (iMRI) is proven to be advantageous in transsphenoidal surgery (TSS) for pituitary adenomas. We evaluated the efficacy of low-field iMRI. Also, we described several techniques to enhance the visibility of the tumor resection margin. METHODS: Two hundred twenty-nine patients who underwent TSS using low-field iMRI were analyzed. iMRI was acquired in cases where the tumor removal was thought to meet the surgical goal after the tumor resection cavity had been packed with contrast-soaked cotton pledgets to improve the visibility of the tumor resection margin. Suspicious remnants were localized and explored using updated iMRI-based semi-real-time navigation. A merging technique was adopted for very small tumors. The final outcome was evaluated using postoperative 3-T diagnostic magnetic resonance imaging (MRI). RESULTS: Among 198 patients in whom total resection was attempted, total resection seemed to have been achieved in 184 patients based on iMRI findings. However, immediate postoperative MRI revealed remnant tumors in 4 out of 184 patients (false-negative rate, 2.2 %). The other 31 patients underwent intended subtotal resection of the tumors. Overall, in 47 patients (20.5 %), the use of iMRI led to further resection. Those patients benefited from the use of iMRI to achieve the planned extent of tumor resection. CONCLUSIONS: iMRI maximizes the extent of resection and minimizes the possibility of unexpected tumor remnants in TSS for pituitary adenomas. It is essential to reduce imaging artifacts and enhance the visibility of the tumor resection margin during the use of low-field iMRIope

Coexistence of intracranial aneurysm in 800 patients with surgically confirmed pituitary adenoma

OBJECT: The purpose of this study was to assess factors associated with intracranial aneurysm (IA) in patients with pituitary adenoma (PA). In addition, these patients were compared with a control group from the general patient population in terms of the age-matched prevalence rate and the pattern of distribution of IA. METHODS: The authors retrospectively reviewed 800 patients who received transsphenoidal surgery for PA and 3850 control patients from the general patient population who were evaluated for routine health care at the authors' institution between 2004 and 2010. All patients underwent MR imaging and MR angiography. Hormone assessment and pathological examination performed using immunohistochemical (IHC) staining were completed for patients with PA. RESULTS: Coexistence of IA in patients with PA was detected in 18 patients (2.3%). Multivariate analysis showed that age (p = 0.04) and cavernous sinus invasion (p < 0.001) were correlated with the increased incidence of IA, but hormone type, IHC staining, and sex were not associated. An age-matched comparison of the prevalence of IA showed an increased prevalence in patients with PA compared with the controls (p = 0.014), and when categorized according to age by decade, the 6th decade was significantly different (p = 0.039). However, the intracranial distribution pattern of IA did not demonstrate a significant difference. CONCLUSIONS: Older age and the existence of a cavernous sinus invasion were correlated with increased incidence of IA in patients with PA. An age-matched comparison showed an increased incidence of IA in patients with PA than in the controls.ope