• 한국의학물리학회지:의학물리
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• 제31권3호
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• pp.63-70
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• 2020

Stereotactic radiosurgery is one of the most sophisticated forms of modern advanced radiation therapy. Unlike conventional fractionated radiotherapy, stereotactic radiosurgery uses a high dose of radiation with steep gradient precisely delivered to target lesions. Lars Leksell presented the principle of radiosurgery in 1951. Gamma Knife^® (GK) is the first radiosurgery device used in clinics, and the first patient was treated in the winter of 1967. The first GK unit had 179 cobalt 60 sources distributed on a hemispherical surface. A patient could move only in a single direction. Treatment planning was performed manually and took more than a day. The latest model, Gamma Knife^® Icon^TM, shares the same principle but has many new dazzling characteristics. In this article, first, a brief history of radiosurgery was described. Then, the physical properties of modern radiosurgery machines and physicists' endeavors to assure the quality of radiosurgery were described. Intrinsic characteristics of modern radiosurgery devices such as small fields, steep dose distribution producing sharp penumbra, and multi-directionality of the beam were reviewed together with the techniques to assess the accuracy of these devices. The reference conditions and principles of GK dosimetry given in the most recent international standard protocol, International Atomic Energy Agency TRS 483, were shortly reviewed, and several points needing careful revisions were highlighted. Understanding the principles and physics of radiosurgery will be helpful for modern medical physicists.

• Journal of Korean Neurosurgical Society
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• 제46권4호
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• pp.360-364
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• 2009

Objective : Several treatment options have proven effective for metastatic brain tumors, including surgery and stereotactic radiosurgery. Tumors with cystic components, however, are difficult to treat using a single method. We retrospectively assessed the outcome and efficacy of gamma knife radiosurgery (GKRS) for cystic brain metastases after stereotactic aspiration of cystic components to decrease the tumor volume. Methods : The study population consisted of 24 patients (13 males, 11 females; mean age, 58.3 years) with cystic metastatic brain tumors treated from January 2002 to August 2008. Non-small cell lung cancer was the most common primary origin. After Leksell stereotactic frame was positioned on each patient, magnetic resonance images (MRI)-guided stereotactic cyst aspiration and GKRS were performed (mean prescription dose : 20.2 Gy). After treatment, patients were evaluated by MRI every 3 or 4 months. Results : After treatment, 13 patients (54.2%) demonstrated tumor control, 5 patients (20.8%) showed local tumor progression, and 6 patients (25.0%) showed remote progression. Mean follow-up duration was 13.1 months. During this period, 10 patients (41.7%) died, but only 1 patient (4.2%) died from brain metastases. The overall median survival after these procedures was 17.8 months. Conclusion : These results support the usefulness of GKRS after stereotactic cyst aspiration in patients with large cystic brain metastases. This method is especially effective for the patients whose general condition is very poor for general anesthesia and those with metastatic brain tumors located in eloquent areas.

• Journal of Korean Neurosurgical Society
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• 제61권5호
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• pp.633-639
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• 2018

Objective : We investigated the outcomes of repeat stereotactic radiosurgery (SRS) for metastatic brain tumors that locally recurred despite previous SRS, focusing on the tumor control. Methods : A total of 114 patients with 176 locally recurring metastatic brain tumors underwent repeat SRS after previous SRS. The mean age was 59.4 years (range, 33 to 85), and there were 68 male and 46 female patients. The primary cancer types were non-small cell lung cancer (n=67), small cell lung cancer (n=12), gastrointestinal tract cancer (n=15), breast cancer (n=10), and others (n=10). The number of patients with a single recurring metastasis was 95 (79.8%), and another 19 had multiple recurrences. At the time of the repeat SRS, the mean volume of the locally recurring tumors was 5.94 mL (range, 0.42 to 29.94). We prescribed a mean margin dose of 17.04 Gy (range, 12 to 24) to the isodose line at the tumor border primarily using a 50% isodose line. Results : After the repeat SRS, we obtained clinical and magnetic resonance imaging follow-up data for 84 patients (73.7%) with a total of 108 tumors. The tumor control rate was 53.5% (58 of the 108), and the median and mean progression-free survival (PFS) periods were 246 and 383 days, respectively. The prognostic factors that were significantly related to better tumor control were prescription radiation dose of 16 Gy (p=0.000) and tumor volume less than both 4 mL (p=0.001) and 10 mL at the repeat SRS (p=0.008). The overall survival (OS) periods for all 114 patients after repeat SRS varied from 1 to 56 months, and median and mean OS periods were 229 and 404 days after the repeat SRS, respectively. The main cause of death was systemic problems including pulmonary dysfunction (n=58, 51%), and the identified direct or suspected brain-related death rate was around 20%. Conclusion : The tumor control following repeat SRS for locally recurring metastatic brain tumors after a previous SRS is relatively lower than that for primary SRS. However, both low tumor volume and high prescription radiation dose were significantly related to the tumor control following repeat SRS for these tumors after previous SRS, which is a general understanding of primary SRS for metastatic brain tumors.

• Journal of Korean Neurosurgical Society
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• 제29권5호
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• pp.650-658
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• 2000

Objective : To evaluate the role of Gamma Knife radiosurgery in essential and tumor-related(secondary) trigeminal neuralgia, outcomes of radiosurgery and microsurgery were compared each other. Methods : Five patients with essential trigeminal neuralgia underwent stereotactic radiosurgical treatment with Leksell Gamma Knife and twenty five patients were treated with microsurgery during the same period(1994. 1-1997. 6). A 4-mm collimator was used and REZ or proximal portion of trigeminal nerve was targeted with maximal dose of 60-72Gy. The mean follow-up after radiosurgery was 39.4 months and that after microsurgery was 47.9 months. Results : At the last follow-up, four patients(80%) had excellent(pain free) or good(50-90% pain relief) outcomes, one(20%) had poor control after radiosurgical treatment. Twenty-three patients(92%) had excellent or good outcomes and two(8%) had poor results after microsurgery. Postoperative complications occurred in ten(40%) with microsurgery, but there were no complications in patients with Gamma Knife radiosurgery. Six patients with secondary trigeminal neuralgia received radiosurgical treatment directed at their tumors, and three patients were surgically treated. Three of six(50%) patients treated with Gamma Knife had pain relief while two of three patients with surgical treatment showed immediate pain relief. Post-treatment complications were developed in two of six radiosurgical patients and in one of three surgical patients. Conclusion : Gamma Knife stereotactic radiosurgery may be considered as a useful and alternative option for the treatment of essential and secondary trigeminal neuralgia owing to of its safety and less complications. The preliminary results obtained in our series appear encouraging, although the outcome is not so good as that of surgery.

• 종양간호연구
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• 제12권4호
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• pp.323-330
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• 2012

Purpose: Gamma knife radiosurgery (GKR) requires frame positioning because the treatment target should be as close as possible to the center of the frame. The purpose of this study was to identify the level of pin-fixing (PFP) and removal pain (PRP), and the associated factors with the pain undergoing GKR. Methods: A total of 116 patients who underwent GKR for their brain tumor were recruited from C University hospital located in H city, J province. The level of pain was measured by the 10 cm VAS. Results: The level of PFP and PRP were 6.36 and 3.26 points, respectively. Step-wise multiple regressions found that the group who have not perceived numbness after applying 5% EMLA cream was the highest associated factor with PFP, following the time from lidocaine injection to pin-fixation, which explained 21% of total variance of the level of PFP. On the other hand, a group who did not perceive numbness after applying 10% lidocaine spray was the highest factor with PRP, among female patients, which explained 27% of total variance of the level of PRP. Conclusion: Both of PFP and PRP of the stereotactic frame were moderate so that nurses should consider diverse strategies to reduce pain among patients undergoing gamma knife radiosurgery.

• Journal of International Society for Simulation Surgery
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• 제2권2호
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• pp.58-63
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• 2015

Image-guided neurosurgery (IGN) is a technique for localizing objects of surgical interest within the brain. In the past, its main use was placement of electrodes; however, the advent of computed tomography has led to a rebirth of IGN. Advances in computing techniques and neuroimaging tools allow improved surgical planning and intraoperative information. IGN influences many neurosurgical fields including neuro-oncology, functional disease, and radiosurgery. As development continues, several problems remain to be solved. This article provides a general overview of IGN with a brief discussion of future directions.

• Journal of Korean Neurosurgical Society
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• 제57권2호
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• pp.77-81
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• 2015

Objective : The purpose of this study was to investigate changes in the plasma level of vascular endothelial growth factor (VEGF) after Gamma Knife radiosurgery (GKRS) for the treatment of meningioma. Methods : Fourteen patients with meningiomas had peripheral venous blood collected at the time of GKRS and at 1 week, 1 month, 3 month and 6 month visits. Plasma VEGF levels were measured using commercially available enzyme-linked immunosorbent assay. For controls, peripheral blood samples were obtained from 20 healthy volunteers. Results : The mean plasma VEGF level (29.6 pg/mL) in patients with meningiomas before GKRS was significantly lower than that of the control group (62.4 pg/mL, p=0.019). At 1 week after GKRS, the mean plasma VEGF levels decreased to 23.4 pg/mL, and dropped to 13.9 pg/mL at 1 month, 14.8 pg/mL at 3 months, then increased to 27.7 pg/mL at 6 months. Two patients (14.3%) with peritumoral edema (PTE) showed a level of VEGF 6 months after GKRS higher than their preradiosurgical level. There was no significant association found in an analysis of correlation between PTE and tumor size, marginal dose, age, and sex. Conclusion : Our study is first in demonstrating changes of plasma VEGF after stereotactic radiosurgery (SRS) for meningioma. This study may provide a stimulus for more work related to whether measurement of plasma level has a correlation with tumor response after SRS for meningioma.

• 한국의학물리학회지:의학물리
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• 제9권3호
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• pp.175-184
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• 1998

감마나이프를 이용하는 정위적 방사선 수술 치료계획 프로그램 중에서 선량계산 프로그램을 PC에서 작성하고, 작성한 프로그램 GP1(Gamma Project 1) 을 상용화된 치료계획 프로그램인 KULA와 비교하여 선량분포 50% 지점에서 등선량분포의 차이와 편차를 계산함으로써 GPI을 평가하고자 한다. 또한 radiochromic 필름에 감마나이프로 방사선을 조사하여 선량분포를 계산하고, 이를 KULA, GPI에 의한 선량분포와 비교하여 GPI을 검증하고자 한다. 프로그램 작성은 프로그램 제작 언어인 IDL(Interactive Data Language)을 사용하였으며, 선량계산 알고리듬은 상용 치료계획 프로그램인 KULA의 알고리듬을 사용하였다. GP1을 평가하기 위해 반경이 80 mm인 구형 팬톰 중심에서 각 콜리메이터마다 세 방향 (축상면, 시상면, 관상면)에서의 선량분포를 계산하고, 이를 KULA에 의한 선량분포와 비교하였다. 또한 팬톰내 임의의 한 지점에서 GPl과 KULA에 의한 선량분포를 비교하여 두 프로그램간의 선량분포 차이를 계산하였다. 이를 검증하기 위해 팬톰 내부에 radiochromic 필름올 장치하여 방사선을 조사한 후 필름의 선량분포를 상용화된 프로그램 KULA와 본 연구에서 작성한 프로그램 GP1에 의한 선량분포와 비교하여 그 차이를 확인하였다. 그 결과 팬톰 중심에서 GPl과 KULA에 의한 선량분포는 50% 선량분포에서 $\pm$3% 이내의 편차를 나타내었으며, 임의의 지점에서도 같은 결과를 보여주었다. 콜리메이터 크기가 작고 선량분포의 값이 작을수록 두 프로그램의 차이가 커짐을 알 수 있었다. GPl 검증을 위한 필름에서의 선량분포 또한 두 프로그램에서의 선량분포와 잘 일치함을 알 수 있었다. 이로써 치료계획시 GPl에 의한 선량분포의 사용이 가능성을 확인하였다.

• 한국의학물리학회지:의학물리
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• 제7권2호
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• pp.19-28
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• 1996

정위적 방사선수술 (Stereotactic radiosurgery) 은 병소(region)의 위치를 정확히 결정하고 치료에 요구되는 방사선량이 정확히 전달되는 것이 중요하다. 본 연구는 이를 실험적으로 확인할 목적으로 특별히 고안된 물팬텀 (water phantom)을 개발하여 Leksell 정위기구 (Leksell Stereotactic Frame; LSF)에 부착하여 방사선수술을 시행하였다. 방사선 수술에는 Leksell 감마나이프 (Gamma Knife Unit; GKU) 와 LSF를 사용하였으며 실험을 위해 개발된 팬텀은 1mm 두께 플라스틱의 직경 160mm의 구형으로 물을 채울수 있는 구조로 되어있다. 측정장치로서는 목표점 설정(target localization)을 위한 필름과 전달 선량(dose delivery) 측정을 위해 이온 전리함(ionchamber) 을 사용하였으며 이를 팬텀의 목표점에 각각 위치시킬 수 있도록 설계하였다. 본 연구에서 목표점 확인은 허용 오차범위인 $\pm$0.5 mm 이내에서의 값을 보였으며 선량전달값은 $\pm$3% 정도의 오차로 허용값내에 있음을 보여주었다. 본 연구에서 개발된 팬텀으로 측정된 값이 모두 허용 오차범위 내에 있음을 보여주었고 이로인해 GKU 및 LSF의 주기적 QA(Quality Assurance)에 계속적으로 사용할수 있게 되었다.

• Radiation Oncology Journal
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• 제13권1호
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• pp.87-94
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• 1995

Since March 1992, total 200 patients who visited our hospital as functional or organic lesions of central nervous system were treated by gamma knife stereotactic radiosurgery for 27 months. Thirty-nine patients of total cases was diagnosed as cerebral arteriovenous malformation. The rate of magnification on X-ray film was reduced by cutting fixation adaptor from 1.0 to below 1.45 times. In order to treat the deep- and lateral-seated cerebral arteriovenous malformation, we slightly modified the angiographic indicator, the commercial Leksell system, by cutting each inner sides about 5mm, We performed the more distinction of the scales by adapting 0.5mm or 1mm copper filter to angiographic indicator. The center point of indicator(X=100mm, Y=100mm, Z=100mm) is corrected by adjusting scales of X-, Y-, Z-axis to each inner 100 and outer 100 point within 1-2mm by repeated exposure of X-ray on films in trial-and-errors. We have developed the 'GKANGIO' programed as the Fortran-77 in Microvax - 3100, which can save treatment planning time and perform accurate pretreatment planning using the theoretical target metrix center. The theoretical description of the simplified method is presented for the reduction of experimental and numerical errors in treatment planning of radiosurgery.