• Journal of Korean Neurosurgical Society
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• v.30 no.11
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• pp.1263-1270
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• 2001

Objective : To analyze the radiosurgical results of intracranial meningiomas after Gamma Knife radiosurgery (GKS) and to assess the possible factors related to the outcome and complications in treating meningiomas. Patients and Methods : We retrospectively reviewed the clinical and radiological data in 179 patients(194 lesions) treated with GKS for intracranial meningiomas between May 1992 and October 2000. Radiosurgical responses were categorized as shrinkage, stasis and enlargement, and we defined the shrunken and static group as a radio-logical control. A Cox proportional hazards model was used to evaluate the correlation between the radiosurgical outcomes and various factors such as location and size of tumor, age and gender of patients, relation to venous sinus, pre-GKS degree of edema, treatment modality, radiosurgical parameters, and pathologic findings. Results : Patients were grouped into skull base meningiomas(57.7%), non-skull base tumor including convexity, parasagittal, and falx meningiomas(37.1%), and others(5.2%) according to the location of tumors. The mean maximum dose and the margin dose of tumor was 30.0Gy(19-45Gy) and 15.1Gy(9.5-24.5Gy), respectively. The mean volume of the tumors was 9.4cc(0.003-45.0cc). The radiologic control rate was 97.1%. The radiation induced imaging change with or without neurologic deficit was the most common complication(23.6%). There were seen mostly in convexity, parasagittal, and falx meningiomas which were deeply embedded in cortex. Conclusion : GKS for intracranial meningioma seems to be safe and effective treatments. However, GKS should be considered very cautiously in non-skull base tumor such as convexity, parasagittal, or falx meningiomas with regards to patient's age and general condition, size and location of tumor, pattern of embedding into cortex, presenting symptoms and patient's preference.

• Radiation Oncology Journal
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• v.33 no.3
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• pp.207-216
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• 2015

Purpose: Stereotactic radiosurgery (SRS) has been introduced for small-sized single and oligo-metastases in the brain. The aim of this study is to assess treatment outcome, efficacy, and prognostic variables associated with survival and intracranial recurrence. Materials and Methods: This study retrospectively reviewed 123 targets in 64 patients with non-small cell lung cancer (NSCLC) treated with SRS between January 2006 and December 2012. Treatment responses were evaluated using magnetic resonance imaging. Overall survival (OS) and intracranial progression-free survival (IPFS) were determined. Results: The median follow-up was 13.9 months. The median OS and IPFS were 14.1 and 8.9 months, respectively. Fifty-seven patients died during the follow-up period. The 5-year local control rate was achieved in 85% of 108 evaluated targets. The 1- and 2-year OS rates were 55% and 28%, respectively. On univariate analysis, primary disease control (p < 0.001), the Eastern Cooperative Oncology Group (ECOG) performance status (0-1 vs. 2; p = 0.002), recursive partitioning analysis class (1 vs. 2; p = 0.001), and age (<65 vs. ${\geq}65$ years; p = 0.036) were significant predictive factors for OS. Primary disease control (p = 0.041) and ECOG status (p = 0.017) were the significant prognostic factors for IPFS. Four patients experienced radiation necrosis. Conclusion: SRS is a safe and effective local treatment for brain metastases in patients with NSCLC. Uncontrolled primary lung disease and ECOG status were significant predictors of OS and intracranial failure. SRS might be a tailored treatment option along with careful follow-up of the intracranial and primary lung disease status.

• Radiation Oncology Journal
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• v.37 no.4
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• pp.265-270
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• 2019

Purpose: Renal cell carcinoma (RCC) and melanoma have been considered 'radioresistant' due to the fact that they do not respond to conventionally fractionated radiation therapy. Stereotactic radiosurgery (SRS) provides high-dose radiation to a defined target volume and a limited number of studies have suggested the potential effectiveness of SRS in radioresistant histologies. We sought to determine the effectiveness of SRS for the treatment of patients with radioresistant brain metastases. Materials and Methods: We performed a retrospective review of our institutional database to identify patients with RCC or melanoma brain metastases treated with SRS. Treatment response were determined in accordance with the Response Evaluation Criteria in Solid Tumors. Results: We identified 53 radioresistant brain metastases (28% RCC and 72% melanoma) treated in 18 patients. The mean target volume and coverage was 6.2 ± 9.5 mL and 95.5% ± 2.9%, respectively. The mean prescription dose was 20 ± 4.9 Gy. Forty lesions (75%) demonstrated a complete/partial response and 13 lesions (24%) with progressive/stable disease. Smaller target volume (p < 0.001), larger SRS dose (p < 0.001), and coverage (p = 0.008) were found to be positive predictors of complete response to SRS. Conclusion: SRS is an effective management option with up to 75% response rate for radioresistant brain metastases. Tumor volume and radiation dose are predictors of response and can be used to guide the decision-making for patients with radioresistant brain metastases.

• Journal of Korean Neurosurgical Society
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• v.30 no.5
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• pp.567-574
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• 2001

Objective : As for growth hormone(GH) secreting pituitary adenoma, it's remission should be declared on the basis of satisfactory controlling of the tumor, normalization of hormonal level, and symptomatic improvement of the patient. Several modalities of treatment have been applied and administered, and yet, this disease still remains as inveterate one to be fully treated. The purpose of this study is to evaluate the outcome of gamma knife radiosurgery(GKRS) for GH secreting pituitary adenoma, and to identify various factors affecting the outcome of the treatment. Method : A group of 24 out of 35 patients, treated by Leksell gamma knife unit during the period of March of 1992 through October of 1997, had been observed for more than two years. The mean target volume of microadenoma was $449.3mm^3(range 216-880mm^3)$, and that of macroadenoma was $3183.1mm^3(range 1456-13125mm^3)$. The tumor margin was covered with 50% isodose profile, and mean marginal dose was 25.2Gy(range 15-32.4Gy). The mean number of isocenter was 4.3(range 1-6). The exposed dose to the optic apparatus was less than 8Gy. The mean follow-up period was 37.8months(range 24-102months). Result : No patients showed any increase in the tumor volume during the follow-up period. And definite shrinkage of tumor volume(tumor volume reduction rate, TVRR : more than 50%) was obtained in 10 patients(41.7%). Twenty one patients(87.5%) had reduced hormonal level compared than pre-treatment level. Among them, normalization of the hormonal level was achieved in 12 patients(50%). Clinicoendocrinological remission was seen in 3 patients (12.5%). According to the results of statistical analysis, tumor volume(p=0.016),duration of symptoms(p=0.046), initial GH level(p=0.017), and the invasion of cavernous sinus(p=0.036) were significantly favorable to post-radiosurgical outcome. The TVRR was significantly related to post-radiosurgical reduction of serum GH level. Permanent complication was not seen. Conclusion : The authors concluded that GKRS is a safe and effective treatment modality for acromegaly. To otain the better outcome of GKRS in GH secreting pituitary adenoma, more careful and sophisticated treatment-planning is recommended.

• Journal of Korean Neurosurgical Society
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• v.50 no.2
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• pp.99-102
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• 2011

Objective : The purpose of this retrospective study was to evaluate the outcome of gamma knife radiosurgery (GKRS) and/or whole brain radiation therapy (WBRT) for the treatment of small cell lung carcinoma (SCLC) metastasis to the brain. Methods : From 2000 to 2010, 50 patients underwent GKRS for metastatic brain lesions originating from SCLC. Among these patients, 11 received prophylactic cranial irradiation (PCI) before the development of metastatic lesions (PCI group), and GKRS was performed as an initial treatment for newly diagnosed lesions in 12 patients who had not received PCI (primary GKRS group). In addition, GKRS was performed as a salvage treatment for progressive lesions after WBRT in 27 patients (salvage GKRS group). The medical records and imaging data of all patients were retrospectively analyzed. Results : The overall survival of the 50 patients was 20.8 months (range 1-53) after the diagnosis of primary tumor and 12.0 months (range 1-47) after the development of cerebral metastasis. Median survival after GKRS was 4.8 months (range 1-15) in the PCI group, 4.6 months (range 0-18) in the primary GKRS group, and 7.6 months (range 0-33) in the salvage GKRS group. Further treatment for progressive lesions after GKRS was necessary in 15 patients, after a mean interval of 3.8 months. Causes of death were systemic organ failure in 15 patients, deterioration of neurological state in 13 patients, and unknown or combined causes in 16 patients. The local control rate of the lesions treated with GKRS was 76.4% (decreased in 13 patients and stable in 16 patients at the final imaging follow-up (mean 5.60 months). Conclusion : GKRS is an effective local treatment for brain metastasis from SCLC both as an initial treatment for newly diagnosed lesions after PCI and as a salvage treatment for recurrent or progressive lesions. However, the survival benefit is not significant because most patients die of systemic multi-organ failure with a short life expectancy.

• Journal of Korean Neurosurgical Society
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• v.44 no.4
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• pp.199-204
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• 2008

Objective : This study was designed to compare the efficacy of micro-vascular decompression (MVD) and Gamma knife radiosurgery (GKRS) for elderly idiopathic trigeminal neuralgia patients by analyzing the clinical outcome. Methods : In the past 10 years, 27 elderly patients were treated with MVD while 18 patients were treated with GKRS (>65-years-old). We reviewed their clinical characteristics and clinical courses after treatment as well as the treatment outcomes. For patients who were treated with MVD, additional treatment methods such as rhizotomy were combined in some areas. In GKRS, we radiated the root entry zone (REZ) with the mean maximum dose of 77.8 (70-84.3) Gy and one 4 mm collimator. Results : The mean age was 68.1 years for MVD, and 71.1 years for GKS group. The average time interval between first presenting symptom and surgery was 84.1 (1-361) months, and 51.4 (1-120) months, respectively. The mean follow-up period after the surgery was 35.9 months for MVD, and 33.1 months for GKRS. According to Pain Intensity Scale, MVD group showed better prognosis with 17 (63%) cases in grade I-II versus 10 (55.6%) cases in GKRS group after the treatment. The pain recurrence rate during follow up did not show much difference with 3 (11.1%) in MVD, and 2 (11.1%) in GKRS. After the treatment, 2 cases of facial numbness, and 1 case each of herpes zoster, cerebrospinal fluid (CSF) leakage, hearing disturbance, and subdural hematoma occurred in MVD Group. In GKRS, there was 1 (5.6%) case of dysesthesia but was not permanent. Three cases were retreated by GKRS but the prognosis was not as good as when the surgery was used as primary treatment, with 1 case of grade I-II, and 1 case of recurrence. The maximal relieve of pain was seen just after surgery in MVD group, and 1 year after treatment in GKRS group. Conclusion : For trigeminal neuralgia patients with advanced age, MVD showed advantages in immediately relieving the pain. However, in overall, GKRS was preferable, despite the delayed pain relief, due to the lower rate of surgical complications that arise owing to the old age.

• Journal of Korean Neurosurgical Society
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• v.40 no.5
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• pp.336-341
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• 2006

Objective : The authors conducted a retrospective study to evaluate the preservation rates of serviceable hearing and to determine its prognostic factors after gamma knife stereotactic radiosurgery[GK SRS] in the patient with vestibular schwannomas. Methods : Between December 1997 and March 2005, 54 patients with a sporadic vestibular schwannoma and serviceable hearing [Gardner Robertson grade I-II] were enrolled in this study. Electronic database of medical records and radiological examinations before and after GK SRS were investigated to the last follow up. The mean marginal dose was $12.3{\pm}0.7Gy$. The mean maximum dose delivered to the tumor center was 24.7Gy [$22{\sim}30Gy$]. The median tumor volume was 2cc [$0.1{\sim}9.1cc$]. The median follow-up period of magnetic resonance[MR] imaging was 31 months [$6{\sim}99\;months$], and the mean follow-up period of audiometry was 24 months [$4{\sim}70\;months$]. Results : The tumor control rate was 100% in the patients with the follow up period more than 2 years. The trigeminal and facial nerve preservation rates were 98% and 100%, respectively. Twenty-eight [52%] of the 54 patients preserved serviceable hearing and 16 [30%] patients retained their pre-GK G-R grade level after GK SRS. In the univariate and multivariate analysis, there was no significant prognostic factor in preservation of the serviceable hearing. Conclusion : The hearing preservation rate is still unsatisfactory compared with the results of other cranial nerve preservation and tumor control in the treatment of vestibular schwannoma by GK SRS. More sophisticated strategy during and after GK SRS is necessary to improve long-term hearing preservation.

• Journal of Korean Neurosurgical Society
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• v.29 no.9
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• pp.1228-1232
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• 2000

Objective : This study was undertaken to analysis gamma knife radiosurgery(GKR) effect for trigeminal neuralgia after long term follow-up. Methods : There were 11 trigeminal neuralgia patients. The authors irradiated 67-85 Gy maximally to the nerve root entry zone(NREZ) using single 4mm collimator, just 1-6mm lateral side from the junction of the trigeminal nerve and pons. For the first 3 cases, we targeted the junction between the nerve and the pons. In theses cases, the pons was irradiated 56 or 60 gray in the surface. In the later 8 cases, the isocenter is positioned more distal side so that the brain stem surface would receive less than the 20% isodose. Results : The average follow-up duration was 25 months(13-50 months). Pain relief was noticed within a week to 5 months. In 3 patients, pain was relieved completely and in other 3 patients, mark improvement was achieved(80-90%). Remaining 4 patients showed significant improvement(30-50%). There was recurrence in only one case and she complained with similar intensity of pain at the last follow-up. There was no significant complication related to GKR. Conclusion : GKR is considered effective for trigeminal neuralgia based on the long term follow-up evaluation, but more clinical experience is needed to evaluate the efficacy of GKR for trigeminal neuralgia as a primary treatment modality.

• Progress in Medical Physics
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• v.20 no.1
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• pp.43-50
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• 2009

The 4 bank mico-MLC (mMLC; Acculeaf, Direx, Isral) has been commissioned for clinical use of linac based stereotactic radiosurgery. The geometrical parameters to control the leaves were determined and comparisons between measured and calculated by the calculation model were performed in terms of absolute dose (cGy/100 MU). As a result of evaluating calculated dose for various field sizes and depths of 5 and 10 cm in water in the geometric condition of fixed SSD (source to surface distance) and fixed SCD (source to chamber distance), most of differences were within 1% for 6 MV and 15 MV x-rays. The penumbral widths at the isocenter were approximately evaluated to 0.29~0.43 cm depending on the field size for 6 MV and 0.36~0.51 cm for 15 MV x-rays. The average transmission and leakage for 6 MV and 15 MV x-rays were 6.6% and 7.4% respectively in single level of leaves fully closed. In case of dual level of leaves fully closed the measured transmission is approximately 0.5% for both 6 MV and 15 MV x-rays. Through the commissiong procedure we could verify the dose characteristics of mMLC and approximately evaluate the error ranges for treatment planning system.

• Progress in Medical Physics
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• v.14 no.4
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• pp.225-233
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• 2003

The goal of a radiation treatment plan is to deliver a homogeneous dose to a target with minimal irradiation of the adjacent normal tissues. Dose uniformity is especially important for stereotactic radiosurgery using a linear accelerator. The dose uniformity and high dose delivery of a single spherical dose distribution exceed 70％. This also results with a similar stereotactic radiosurgical plan using a Gamma Knife. The dose distribution produced in a stereotactic radiosurgical plan using a Gamma Knife and Linear accelerator is spherical, and the application of the sphere packing arrangement in a real radiosurgical plan requires much time and skill. In this study, we found a characteristic of dose distribution with transformation of beam parameters that must be considered in a radiosurgical plan for effective radiosurgery. First, we assumed a cylinder type tumor model and a cube type tumor model. Secondly, the results of the tumor models were compared and analyzed with dose profiles and DVH_(Dose Volume Histogram) representative dose distribution. We found the optimal composition of beam parameters_(i.e. collimator size, number of isocenter, gap of isocenters etc.), which allowed the tumor models to be involved in the isodose curve at a high level. In conclusion, the characteristics found in this study are helpful for improving the effectiveness and speed of a radiosurgical plan for stereotactic radiosurgery.