• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.1-7
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• 2009

Purpose: The purpose is to evaluate the accuracy of correcting the targeting error through the Target Location System (TLS) for the location change error of the reference point which arises from the movement or motion of patient during the treatment using the CyberKnife. Materials and Methods: In this test, Gafchromic MD-55 film was inserted into the head and neck phantom to analyze the accuracy of the targeting, and then the 6 MV X-ray of CyberKnife (CyberKnife Robotic Radiosurgery System G4, Accuray, US) was irradiated. End to End (E2E) program was used to analyze the accuracy of targeting, which is provided by Accuray Corporation. To compute the error of the targeting, the test was carried out with the films that were irradiated 12 times by maintaining the distance within the rage of $0{\pm}0.2\;mm$ toward x, y, z from the reference point and maintaining the angle within the rage of $0{\pm}0.2^{\circ}$ toward roll, pitch, yaw, and then with the films which were irradiated 6 times by applying intentional movement. And the correlation in the average value of the reference film and the test film were analyzed through independent samples t-test. In addition, the consistency of dose distribution through gamma-index method (dose difference: 3%) was quantified, compared, and analyzed by varying the distance to agreement (DTA) to 1 mm, 1.5 mm, 2 mm, respectively. Results: E2E test result indicated that the average error of the reference film was 0.405 mm and the standard deviation was 0.069 mm. The average error of the test film was 0.413 mm with the standard deviation of 0.121 mm. The result of independent sampling t-test for both averages showed that the significant probability was P=0.836 (confidence level: 95%). Besides, by comparing the consistency of dose distribution of DTA through 1 mm, 1.5 mm, 2 mm, it was found that the average dose distribution of axial film was 95.04%, 97.56%, 98.13%, respectively in 3,314 locations of the reference film, consistent with the average dose distribution of sagittal film that was 95.47%, 97.68%, 98.47%, respectively. By comparing with the test film, it was found that the average dose distribution of axial film was 96.38%, 97.57%, 98.04%, respectively, at 3,323 locations, consistent with the average dose distribution of sagittal film which was 95.50%, 97.87%, 98.36%, respectively. Conclusion: Robotic CyberKnife traces and complements in real time the error in the location change of the reference point caused by the motion or movement of patient during the treatment and provides the accuracy with the consistency of over 95% dose distribution and the targeting error below 1 mm.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.303-312
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• 2017

The central goal of Gamma Knife radiosurgery(GKRS) is to maximize the conformity of the prescription isodose surface, and to minimize the radiation effect of the normal tissue surrounding the target volume. There are the various kinds of indices related with the quality of treatment plans such as conformity index, coverage, selectivity, beam-on time, gradient index(GI), and conformity/gradient index(CGI). As the best treatment plan evaluation tool, we must check by all means conformity index, GI, and CGI among them. Specially, GI and CGI related with complication of healthy normal tissue is more indispensible than conformity index. Then author calculated and statistically analysed CGI, the newly defined conformity/gradient index as well as GI being applied widely using the treatment planning system Leksell GammaPlan(LGP) and the verification method Variable Ellipsoid Modeling Technique(VEMT). In the study 10 patients with intracranial lesion treated by GKRS were included. Author computed the indices from LGP and VEMT requiring only four parameters: the prescribed isodose volume, the volume with dose > 30%, the target volume, and the volume of half the prescription isodose. All data were analyzed by paired t-test, which is statistical method used to compare two different measurement techniques. No statistical significance in GI at 10 cases was observed between LGP and VEMT. Differences in GI ranged from -0.14 to 0.01. The newly defined gradient index calculated by two methods LGP and VEMT was not statistically significant either. Author did not find out the statistical difference for the prescribed isodose volume between LGP and VEMT. CGI as the evaluation index for determining the best treatment plan is not significant statistically also. Differences in CGI ranged from -4 to 3. Similarly newly defined Conformity/Gradient index for GKRS was also estimated as the metric for the evaluation of the treatment plans through statistical analysis. Statistical analyses demonstrated that VEMT was in excellent agreement with LGP when considering GI, new gradient index, CGI, and new CGI for evaluating the best plans of GKRS. Due to the application of the fast and easy evaluation tool through LGP and VEMT author hopes CGI and newly defined CGI as well as gradient indices will be widely used.

• Radiation Oncology Journal
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• v.31 no.4
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• pp.267-272
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• 2013

Although significant advances in the treatment of intrahepatic lesions, it is reported that the prognosis for patients with hepatocellular carcinoma (HCC) who have extrahepatic metastasis remains poor. We report a patient with lung, liver, brain, bone and subcutaneous metastasis from HCC who has survived more than 7 years maintaining relatively good performance status as a result of repeated therapies. A 55-year-old male patient with HCC underwent right lobectomy of the liver and cholecystectomy in September 2006. He received wedge resection for lung metastasis twice (July 2009, January 2011) and Gamma Knife stereotactic radiosurgery for brain metastasis (April 2011). Over the last 3 years, he has developed metastasis in subcutaneous tissues, muscle, and bone with pain. He has undergone 7 courses of radiotherapies for subcutaneous tissues, muscle, and bone metastasis and been prescribed sorafenib and he is still capable of all self-care.

• Journal of Korean Neurosurgical Society
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• v.39 no.2
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• pp.148-151
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• 2006

Dermatofibrosarcoma protuberans[DFSP] is an uncommon fibrohistiocytic tumor characterized by aggressive local invasion and consequent local recurrence rather than distant metastasis. We present a case of a 51-year-old male patient with a typical cutaneous DFSP, which showed local recurrences and distant metastasis to the central nervous system[CNS] and the lung after 15 years from the initial diagnosis. CNS metastatic lesions recurred in 5 months after surgical resection of the first CNS lesion. These metastatic tumors were treated by open surgery and gamma-knife radiosurgery. Despite continuous medication of oral chemotherapeutic agent, the patient died during 1-year follow-up period.

• Journal of Korean Neurosurgical Society
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• v.60 no.3
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• pp.294-300
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• 2017

Hypothalamic hamartoma (HH) is a benign indolent lesion despite the presentation of refractory epilepsy. Behavioral disturbances and endocrine problems are additional critical symptoms that arise along with HHs. Due to its nature of generating epileptiform discharge and spreading to cortical region, various management strategies have been proposed and combined. Surgical approaches with open craniotomy or endoscopy, stereotactic approaches with radiosurgery and gamma knife surgery or radiofrequency thermos-coagulation, and laser ablation have been introduced. Topographical dimension and the surgeon's preference are key factors for treatment modalities. Endoscopic disconnection has been one of the most favorable options performed in treating HHs. Here we discuss presurgical evaluation, patient selection, surgical procedures, and complications.

• Journal of Korean Neurosurgical Society
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• v.38 no.1
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• pp.65-67
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• 2005

Intracranial chloroma may occur in leukemia, although they are rare. A 23-year-old female complained diplopia. Brain magnetic resonance MR imaging showed tumors in the both cavernous sinus, both tentorial and anterior falx. Gamma-Knife radiosurgery was performed with maximal dose; 20Gy, marginal dose; 10Gy. Peripheral blood smear revealed leukemia, and bone marrow aspiration biopsy showed acute lymphocytic leukemia. Two weeks later, MR image for the stereotactic biopsy noticed markedly decreased tumor size. Biopsy result was lymphocytic leukemia. She received conventional radiation therapy, chemotherapy, and bone marrow transplantation. Brain involvement by acute lymphocytic leukemia is very rare. Even though chloroma are sensitive to radiation therapy, prognosis is poor because of the gravity of the underlying disease and association with impending blast transformation. The authors reports a intracranial chloroma by acute lymphocytic leukemia.

• Journal of Korean Neurosurgical Society
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• v.66 no.1
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• pp.12-23
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• 2023

Glossopharyngeal neuralgia (GPN) is a rare disease that must be differentiated from trigeminal neuralgia. The purpose of this article is to provide a comprehensive review of anatomy, pathophysiology, diagnostic criteria, and several options of treatment for GPN. Lessons learned through our experience of treating GPN are presented in detail, as well as cases of misdiagnosis and diagnostic pitfalls. Microvascular decompression (MVD) should be primarily considered for medically intractable GPN. Techniques employed in MVD for GPN are categorized and described. Especially, we underscore the advantages of the 'transposition' technique where insulating material is positioned 'off' the root entry zone (REZ), instead of 'on' it. We believe this 'off-the-REZ' technique can fundamentally prevent recurrence, if applicable. In addition, Gamma Knife radiosurgery can be an alternative option when a patient is ineligible for MVD, though it is categorized as a destructive procedure.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.334-340
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• 2015

Objective : Pineal parenchymal tumors (PPTs) in adults are rare, and knowledge regarding their optimal management and treatment outcome is limited. Herein, we present the clinical results of our series of PPTs other than pineoblastomas managed by stereotactic radiosurgery (SRS) at upfront setting. Methods : Between 1997 and 2014, nine consecutive adult patients with the diagnosis of PPTs, either pineocytoma or pineal parenchymal tumor of intermediate differentiation, were treated with SRS. There were 6 men and 3 women. The median age was 39 years (range, 31-53 years). All of the patients presented with symptoms of hydrocephalus. Endoscopic third ventriculostomy and biopsy was done for initial management. After histologic diagnosis, patients were treated with Gamma Knife with the mean dose of 13.3 Gy (n=3) or fractionated Cyberknife with 32 Gy (n=6). Results : After a mean follow-up of 78.6 months (range, 14-223 months), all patients were alive and all of their tumors were locally controlled except for one instance of cerebrospinal fluid seeding metastasis. On magnetic resonance images, tumor size decreased in all patients, resulting in complete response in 3 patients and partial response in 6. One patient had experienced temporary memory impairment after SRS, which improved spontaneously. Conclusion : SRS is effective and safe for PPTs in adults and can be considered as a useful alternative to surgical resection at upfront setting.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.458-466
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• 2019

Objective : We retrospectively assessed the efficacy of stereotactic radiosurgery (SRS) for dural arteriovenous fistulas (DAVFs) involving the transverse-sigmoid sinus and analyzed the angiographic and clinical results with our 8-year experience. Methods : Nine patients with intracranial DAVFs involving the transverse-sigmoid sinus underwent SRS using a Gamma $Knife^{(R)}$ (Elekta Inc., Atlanta, GA, USA) between 2009 and 2016. Five patients underwent SRS for residual DAVFs after embolization and four patients were treated with SRS alone. The median target volume was $1.9cm^3$ (range, 0.8-14.2) and the median radiation dose of the target was 17 Gy (range, 16-20). The median follow-up period was 37 months (range, 7-81). Results : Pulsating tinnitus (33%) was the most common symptom. DAVFs were completely obliterated in four patients (44%) and subtotally obliterated in five (56%). Six patients (67%) showed complete recovery of symptoms or signs, and three (33%) showed incomplete recovery. One patient experienced a recurrent seizure. Adverse radiation effects after SRS occurred in one patient (11%). The total obliteration rates after SRS were 16.7%, 37.5%, and 68.7% at 1, 2, and 3 years, respectively. The median interval from SRS to total obliteration of the fistula was 31 months (range, 12-38). The rates at which the symptoms started to improve were 40% at 1 month and 80% at 2 months after SRS. Symptoms started to improve at a median of 5 weeks after SRS (range, 3-21). Conclusion : SRS with or without embolization is a safe and effective treatment to relieve symptoms and obliterate DAVFs on the transverse-sigmoid sinus.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.753-760
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• 2018

Objective : We investigated the effect of optimization in dose-limiting shell method on the dosimetric quality of CyberKnife (CK) plans in treating brain metastases (BMs). Methods : We selected 19 BMs previously treated using CK between 2014 and 2015. The original CK plans ($CK_{original}$) had been produced using 1 to 3 dose-limiting shells : one at the prescription isodose level (PIDL) for dose conformity and the others at low-isodose levels (10-30% of prescription dose) for dose spillage. In each case, a modified CK plan ($CK_{modified}$) was generated using 5 dose-limiting shells : one at the PIDL, another at intermediate isodose level (50% of prescription dose) for steeper dose fall-off, and the others at low-isodose levels, with an optimized shell-dilation size based on our experience. A Gamma Knife (GK) plan was also produced using the original contour set. Thus, three data sets of dosimetric parameters were generated and compared. Results : There were no differences in the conformity indices among the $CK_{original}$, $CK_{modified}$, and GK plans (mean 1.22, 1.18, and 1.24, respectively; p=0.079) and tumor coverage (mean 99.5%, 99.5%, and 99.4%, respectively; p=0.177), whereas the $CK_{modified}$ plans produced significantly smaller normal tissue volumes receiving 50% of prescription dose than those produced by the $CK_{original}$ plans (p<0.001), with no statistical differences in those volumes compared with GK plans (p=0.345). Conclusion : These results indicate that significantly steeper dose fall-off is able to be achieved in the CK system by optimizing the shell function while maintaining high conformity of dose to tumor.