• 한국의학물리학회지:의학물리
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• 제23권3호
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• pp.127-137
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• 2012

Leksell은 뇌동정맥기형종의 중심에 280 kVp 관전압 방사선빔을 집속하는 방법으로 방사선수술법을 고안 시술한 바 있으며, 이 후 코발트-60 감마 선원 201개의 선속이 헬멧콜리메터를 지나 구의 중심에 초점을 이루게 한 감마나이프를 개발하여 표적병변에 높은 선량을 주어 비침습적으로 수술효과를 얻었다. 선형가속기는 높은 선량률과 1 mm 이내의 갠트리회전중심과 안정된 치료대회전 및 선량성능검증효과와 획기적으로 발전된 3차원선량계획 전산화에 힘입어 정밀하고 높은 정확성에 바탕을 둔 비공면궤적으로 방사선을 환부에 집속할 수 있어, 병변 주위의 정상조직에는 낮은 선량이 도달하고 병변에 높은 선량을 줄 수 있는 뇌정위방사선수술에 이용할 수 있게 되었다. 특히 Photon Knife는 환자의 체축을 이용하여 선속이 환부를 중심으로 종횡의 비공면궤적을 이루게 하여 치료선량분포에서 90%와 50% 선량폭을 2~3 mm 까지 좁힐 수 있는 기법을 보였다. 최근 선형가속기의 방사선수술은 2.5~3 mm 폭의 초박형 다엽콜리메터를 이용한 세기조절에 의한 시술이 늘어나는 경향이며, 종전의 종양의 크기에 따른 제한을 넘어 3 cm 이상의 종양에도 시행되고 있다. 뇌정위방사선수술은 선량모델을 뒷받침하는 마이크로 선량계측 및 평가와 성능보증이 필수적이며 선량분포의 경사도를 높이는 기법이 지속적으로 연구되어야 한다. 특히 초박형다엽콜리메터를 이용한 방사선수술은 다엽콜리메터 요철(Tongue and groove) 에 의해 일어나는 표적내 선량저하 부위를 평가하고 균등한 표적선량이 이루어지도록 하며, 마이크로 분해능을 가진 선량검증 방법이 앞으로 더욱 발전할 것으로 보인다.

• 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.

• Journal of Korean Neurosurgical Society
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• 제51권5호
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• pp.276-280
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• 2012

Objective : Gamma knife radiosurgery (GKRS) is the least invasive surgical option for patients with trigeminal neuralgia (TN). However, the indications and long term outcomes of GKRS are still controversial. Additionally, a series with uniform long-term follow-up data for all patients has been lacking. In the present study, the authors analyzed long-term outcomes in a series of patients with TN who underwent a single GKRS treatment followed by a minimum follow-up of 60 months. Methods : From 1994 to 2009, 40 consecutive patients with typical, intractable TN received GKRS. Among these, 22 patients were followed for >60 months. The mean maximum radiation dose was 77.1 Gy (65.2-83.6 Gy), and the 4 mm collimator was used to target the radiation to the root entry zone. Results : The mean age was 61.5 years (25-84 years). The mean follow-up period was 92.2 months (60-144 months). According to the pain intensity scale in the last follow-up, 6 cases were grades I-II (pain-free with or without medication; 27.3%) and 7 cases were grade IV-V (<50% pain relief with medication or no pain relief; 31.8%). There was 1 case (facial dysesthesia) with post-operative complications (4.54%). Conclusion : The long-term results of GKRS for TN are not as satisfactory as those of microvascular decompression and other conventional modalities, but GKRS is a safe, effective and minimally invasive technique which might be considered a first-line therapy for a limited group of patients for whom a more invasive kind of treatment is unsuitable.

• Journal of Korean Neurosurgical Society
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• 제58권1호
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• pp.83-88
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• 2015

Organized hematoma is a rare complication that can develop following gamma knife radiosurgery (GKS) for cerebral arteriovenous malformation (AVM). Here, we describe 5 patients with growing organized hematomas that developed from completely obliterated AVMs several years after GKS. The patients were 15, 16, 30, 36, and 38 years old at the time of GKS, respectively, and 3 patients were female. Four AVMs were located in the lobe of the brain, and the remaining AVM were in the thalamus. Between 2-12 years after GKS, patients developed progressive symptoms such intractable headache or hemiparesis and enhancing mass lesions were identified. Follow-up visits revealed the slow expansion of the hematomas and surrounding edema. Steroids were ineffective, and thus surgery was performed. Histology revealed organized hematomas with a capsule, but there was no evidence of residual AVMs or vascular malformation. After surgery, the neurological symptoms of all patients improved and the surrounding edema resolved. However, the hematoma continued to expand and intraventricular hemorrhage developed in 1 patient whose hematoma was only partially removed. GKS for cerebral AVM can be complicated by growing, organized hematomas that develop after complete obliteration. Growing hematomas should be surgically evacuated if they are symptomatic. Radical resection of the hematoma capsule is also strongly recommended.

• Journal of Korean Neurosurgical Society
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• 제52권4호
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• pp.334-338
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• 2012

Objective : We compared the survival time between patients with multiple gamma knife radiosurgery (GKRS) and patients with a single GKRS plus whole brain radiation therapy (WBRT), in patients with multiple metachronous brain metastases from lung cancer. Methods : From May 2006 to July 2010, we analyzed 31 patients out of 112 patients who showed multiple metachronous brain metastases. 20 out of 31 patients underwent multiple GKRS (group A) and 11 patients underwent a single GKRS plus WBRT (group B). We compared the survival time between group A and B. Kaplan-Meier method and Cox proportional hazards were used to analyze relationship between survival and 1) the number of lesions in each patient, 2) the average volume of lesions in each patient, 3) the number of repeated GKRS, and 4) the interval of development of new lesions, respectively. Results : Median survival time was 18 months (range 6-50 months) in group A and 6 months (range 3-18 months) in group B. Only the average volume of individual lesion (over 10 cc) was negatively related with survival time according to Kaplan-Meier method. Cox-proportional hazard ratio of each variable was 1.1559 for the number of lesions, 1.0005 for the average volume of lesions, 0.0894 for the numbers of repeated GKRS, and 0.5970 for the interval of development of new lesions. Conclusion : This study showed extended survival time in group A compared with group B. Our result supports that multiple GKRS is of value in extending the survival time in patients with multiple metachronous brain metastases, and that the number of the lesions and the frequency of development of new lesions are not an obstacle in treating patients with GKRS.

• Journal of Korean Neurosurgical Society
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• 제61권1호
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• pp.60-65
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• 2018

Objective : Choroidal metastases (CMs) are the most common intraocular tumor. Management is mainly radiation therapy with goals of pain control and visual improvement. However, many radiation-related complications are reported. Since gamma knife radiosurgery (GKS) for CM was first reported in 1995, few cases have been reported. We report 7 cases of CMs treated with GKS. Methods : From April 2011 to November 2014, 7 patients with CM underwent GKS. Their median age at treatment was 64 years (range, 51-71 years). Four males and three females were treated. Lung cancer was the most common primary pathology, followed by renal cell carcinoma and stomach cancer. Four patients had multiple cerebral lesions and were treated simultaneously for choroidal lesions. The median marginal dose of 20 Gy (range, 15-25 Gy) was administered at the 50% isodose line. Results : Median follow-up period after GKS was 8 months (range, 2-38.3 months). Four patients expired due to underlying malignancy progression. Except for two patients who were not followed with magnetic resonance image after GKS, all patients showed size reduction in the treated lesions, but a new choroidal lesion appeared in one patient and one recurred. Six of seven patients reported subjectively improved visual symptoms. Visual acuity improved in 2 patients, and 2 were stable upon objective examination. One patient showed no improvement in visual acuity, but ocular pain was relieved; another patient showed improved vision and tumor remission, but visual deterioration recurred. Conclusion : GKS was shown to be safe and effective and should be considered for CM treatment.

• Journal of Korean Neurosurgical Society
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• 제61권4호
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• pp.516-524
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• 2018

Objective : This study aims to determine whether gamma knife radiosurgery (GKR) improves survival in patients with recurrent high-grade gliomas. Methods : Twenty nine patients with recurrent high-grade glioma underwent 38 GKR. The male-to-female ratio was 10 : 19, and the median age was 53.8 years (range, 20-75). GKR was performed in 11 cases of recurrent anaplastic oligodendrogliomas, five anaplastic astrocytomas, and 22 glioblastomas. The median prescription dose was 16 Gy (range, 10-24), and the median target volume was 7.0 mL (range, 1.1-15.7). Of the 29 patients, 13 (44.8%) received concurrent chemotherapy. We retrospectively analyzed the progression-free survival (PFS) and overall survival (OS) after GKR depending on the Eastern Cooperative Oncology Group (ECOG) performance status (PS), pathology, concurrent chemotherapy, radiation dose, and target tumor volume. Results : Starting from when the patients underwent GKR, the median PFS and OS were 5.0 months (range, 1.1-28.1) and 13.0 months (range, 1.1-75.1), respectively. On univariate analysis, the median PFS was significantly long in patients with anaplastic oligodendroglioma, ECOG PS 1, and target tumor volume less than 10 mL (p<0.05). Meanwhile, on multivariate analysis, patients with ECOG PS 1 and target tumor volume less than 10 mL showed improved PFS (p=0.043 and p=0.007, respectively). The median OS was significantly increased in patients with ECOG PS 1 and tumor volume less than 10 mL on univariate and multivariate analyses (p<0.05). Conclusion : GKR could be an additional treatment option in recurrent high-grade glioma, particularly in patients with good PS and limited tumor volume.

• Journal of Korean Neurosurgical Society
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• 제40권3호
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• pp.148-153
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• 2006

Objective : The authors conducted this study to present the long-term treatment outcomes [minimum 2 years] of Gamma knife radiosurgery[GKS] for trigeminal neuralgia[TN] and to demonstrate the correlation of treatment outcomes and the anatomical characteristics of TN. Methods : From 1997 to 2003, 44 consecutive patients suffering from medically intractable pain underwent GKS for TN. A single 4mm collimator was used with a median maximum dose of 80Gy [range $75{\sim}80Gy$] prescribed to the root entry zone of the trigeminal nerve. Median follow up duration was 30 months [range $24{\sim}78\;months$]. Anatomical measurements of trigeminal nerve in magnetic resonance images during GKS planning were correlated with clinical outcome. Results : Twenty-two patients [50%] achieved an excellent outcome [BNI grade I & II], 20 patients [45.5%] a good outcome [grade IIIa & IIIb], and only 2 patients [4.5%] a poor outcome [grade IV & V]. Eleven patients [25.0%] experienced pain recurrence after initial pain relief. Smaller volume of trigeminal nerve area irradiated more than 40Gy was significantly correlated with excellent outcome in both univariate and multivariate analyses respectively [P=0.033 and 0.040]. Conclusion : Anatomical considerations during the planning of GKS would be helpful for predicting clinical outcome in TN.

• Journal of Korean Neurosurgical Society
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• 제52권2호
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• pp.98-102
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• 2012

Objective : To study the clinical significance and relevant factors of radiation-induced intratumoral necrosis (RIN) and peritumoral edema (PTE) after Gamma knife radiosurgery (GKRS) for intracranial meningiomas. Methods : We retrospectively analyzed the data of 64 patients who underwent GKRS for intracranial meningioma. The mean lesion volume was 4.9 cc (range, 0.3-20), and the mean prescription dose of 13.4 Gy (range, 11-18) was delivered to the mean 49.9% (range, 45-50) isodose line. RIN was defined as newly developed or enlarged intratumoral necrosis after GKRS. Results : RIN and new development or aggravation of PTE were observed in 21 (32.8%) and 18 (28.1%) cases of meningioma, respectively during the median follow-up duration of $19.9{\pm}1.0$ months. Among various factors, maximum dose (>25 Gy) and target volume (>4.5 cc) were significantly related to RIN, and RIN and maximum dose (>24 Gy) were significantly related to the development or aggravation of PTE. In 21 meningiomas with development of RIN after GKRS, there was no significant change of the tumor volume itself between the times of GKRS and RIN. However, the PTE volume increased significantly compared to that at the time of GKRS (p=0.013). The median interval to RIN after GKRS was $6.5{\pm}0.4$ months and the median interval to new or aggravated PTE was $7.0{\pm}0.7$ months. Conclusion : A close observation is required for meningiomas treated with a maximum dose >24 Gy and showing RIN after GKRS, since following or accompanying PTE may deteriorate neurological conditions especially when the location involves adjacent critical structures.

• Journal of Korean Neurosurgical Society
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• 제39권2호
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• pp.102-108
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• 2006

Objective : The management of diffuse astrocytomas is one of the most controversial areas in clinical neurooncology. There are numerous reviews and editorials outlining the difficulties in the management of these lesions. In this study, we assess the role of Gamma Knife radiosurgery[GKS] for diffuse astrocytomas. Methods : Twenty-three patients with a diffuse astrocytoma were treated with GKS as a primary or adjuvant method from February 1995 to October 2003. The mean marginal dose was $13.6\;[8.5{\sim}17.5]Gy$ and the mean maximal dose was $27.3\;[17.0{\sim}35.0]Gy$. Local control and the pattern of radiologic response were evaluated. The probable factors affecting local control, such as tumor volume, margin dose, previous history of craniotomy or stereotactic biopsy, and the presence or absence of previous radiotherapy were statistically analyzed. The average duration of follow-up was 39.7 [$11.3{\sim}101.5$] months after GKS. Results : Of the 23 lesions treated, 16 lesions [69.6%] were controlled during the follow-up period. The mean progression-free interval was 57.4 months and the 5-year progression-free rate was 68%. Only tumor volume was found to be a statistically significant factor for local control. Smaller tumors were better controlled by GKS; it was significantly effective in tumors with less than $10cm^3$ volume. Conclusion : GKS could be a valuable therapeutic modality both as a primary treatment and as a postoperative adjuvant therapy in some selected cases.