• Journal of Korean Neurosurgical Society
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• v.41 no.6
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• pp.359-366
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• 2007

Trigeminal neuralgia is a condition associated with severe episodic lancinating facial pain subject to remissions and relapses. Trigeminal neuralgia is often associated with blood vessel cross compression of the root entry zone or more rarely with demyelinating diseases and occasionally with direct compression by neoplasms of the posterior fossa. If initial medical management fails to control pain or is associated with unacceptable side effects, a variety of surgical procedures offer the hope for long-lasting pain relief or even cure. For patients who are healthy without significant medical co-morbidities, direct microsurgical vascular decompression [MVD] offers treatment that is often definitive. Other surgical options are effective for elderly patients not suitable for MVD. Percutaneous retrogasserian glycerol rhizotomy is a minimally invasive technique that is based on anatomic definition of the trigeminal cistern followed by injection of anhydrous glycerol to produce a weak neurolytic effect on the post-ganglionic fibers. Other percutaneous management strategies include radiofrequency rhizotomy and balloon compression. More recently, stereotactic radiosurgery has been used as a truly minimally invasive strategy. It also is anatomically based using high resolution MRI to define the retrogasserian target. Radiosurgery provides effective symptomatic relief in the vast majority of patients, especially those who have never had prior surgical procedures. For younger patients, we recommend microvascular decompression. For patients with severe exacerbations of their pain and who need rapid response to treatment, we suggest glycerol rhizotomy. For other patients, gamma knife radiosurgery represents an effective management strategy with excellent preservation of existing facial sensation.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.1-8
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• 2004

Purpose : What confirm a patient's set-up precisely is an important factor in stereotactic radiosurgery Especially, the tumor is moved by respiration in case of lung cancer. So it is difficult to confirm a exact location by L-gram or EPID. I will verify a exact patient's set-up about this sort of problem by verification system(exactrac 3.0) Materials and Methods : The patient that had lung cancer operated on stereotactic radiosurgery is composed of 6 people. The 5 patients use an ABC tool and 1 patient doesn't use it. I got such a patient's L-gram and EPID image by Body frame(elekta, sweden), compared Ant. image with Lat. one, and then confirmed a set-up. I fused DRR image of CT and X-ray image of Verification system(exactrac 3.0) 3 dimensional, analyzed the coordinate value(vertical, longitudinal, lateral), and then confirmed a difference of existing method. Results : In case of L-gram and EPID, we judge an exact of the patient's set-up subjectively, and on we could treat the patient with radiation. As a result of using Verification system(exactrac 3.0), coordinate value(vertical, longitudinal, lateral) of patient's set-up was comprised within 5mm. We could estimate a difference of the coordinate value visually and objectively. Consequently, Verification system(exactrac 3.0) was useful in judging an exact patient's set-up. Conclusion : In case of Verification system(exactrac 3.0), we can confirm an exact patient's set-up at any time whenever, However, there are several kinds of the demerit. First, it is a complex process of confirmation than the existing process. Second, thickness of CT scan slice is within 3mm. The last, X-ray image has to have shown itself clearly. If we solve this problem. stereotactic radiosurgery will be useful in treating patients why we can confirm an exact patient's positioning easily.

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.25-28
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• 1997

With the advances in radiation therapy technology and equipment, the need for more accurate and safer radiation delivery to the target region has been continuously growing. Stereotactic Radiosurgery(SRS) is a good example of $^{\ast}Accuracy^{\ast}$ but has a substantial risk of causing severe late neurological damages. Fractionated Stereotactic Radiation Therapy(FSRT) is a modification of SRS enabling conventional fractionation with maintaining accuracy using noninvasive and relocatable frame. Verification of mechanical accuracy in FSRT has been done according to the manufacture's recommendations using RLPP, LTLF, and Depth-helmet. In order to reinforce this, we have developed additional novel verification procedure using Linac-grams with the Angiolocalizer attached on the GTC frame, which are then digitized into the planning software(X-Knife) to generate the three dimensional coordinates for cmoparison. This method has been successful in such ways that the anatomical landmarks are identifiable on the Linac-gram films and that the serial comparisons of the stereotactic coordinates of the isocenter are possible with more certainty a along the FSRT course than before.

• Journal of Korean Neurosurgical Society
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• v.30 no.11
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• pp.1308-1313
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• 2001

Object : The goals of radiosurgery include preservation of neurological function and prevention of tumor growth. We document the results of gamma-knife radio-surgery for vestibular schwannoma. Method & Object : Eighty-two patients underwent stereotactic radiosurgery for an vestibular schwannoma from October, 1994 to December, 2000. Sixty-five of these patients were followed up for radiological and clinical evaluation. As pregamma-knife modality, surgical resection were done in 23 patients,and V-P shunt in 2 patients. Initial symptoms were headache(n=45), dizziness(n=16), tinnitus(n=17). While normal facial function(House-Brackmann grade 1) was present in 48 patients(73.8%), other patients showed grade 2 function in 8, grade 3 function in 7,and grade 4 function in 2. The Gardner/Robertson scale was used to code hearing function. Male to female ratio was 1:3. Mean tumor volume was $7.98cm^3$. Mean dose delivered to the tumor margin was 14.2Gy,and mean maximal dose was 28.3Gy. Results : Mean follow-up duration of 19.9 months. Thirty-five showed decrease(53.8%) in size, 19 patients(29.2%) stationary, 3(4.6%) initial decrease follow up increase, 5(7.6%) initial increase follow up decrease,and 59 patients (90.8%) were well controlled. Two patients experienced transient facial neuropathy, one transient trigeminal neuropathy, and one transient hearing deterioration. After gamma-knife radiosurgery, ventriculoperitoneal shunt was done in 4 patients. Conclusions : Gamma-knife radiosurgery can be used to treat postoperative residual tumors as well as in patients with concomitant medical problems in patients with preserved hearing function. Gamma-knife radiosurgery is safe and effective method to treat small, medium sized(less than 3cm in extracanalicular diameter), intracanalicular vestibular schwannoma, associated with low rate of cranial neuropathy.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.1030-1036
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• 2000

Objective : The aim of this study was to retrospectively analyze the safety and effect of Linac based Photon Knife Radiosugery System(PKRS) for treatment of cerebral arteriovenous malformation. Patients and Methods : The authors analyzed the clinical method and results of ten patients who were followed up more than two years, among the 18 patients who had radiosurgery on arteriovenous malformation from June, 1992, to Dec. 1997, with Linac based Photon knife radiosurgery system(PKRS) which was developed in our hospital. Results : The average age of the patients was 30.4(with the range of 13-49), and the sex was seven males and three females. For the initial clinical symptoms, there were five patients with headache, three with seizure, one with hemiparesis, and one with vomiting. Before the radiosurgery, computed tomography, MRI, and cerebral angiogram were done. For the location of arteriovenous malformation, it was found on six patients of cerebral hemisphere, two of thalamus, one of brainstem, and one of corpus callosum. Regarding the size of nidus, there were seven patients of smaller than 3cm, and three patients of larger than 3cm. Computed tomography, MRI, and cerebral angiogram were done periodically for sixth months, first year, and second year after the radiosurgery of PKRS for the completeness of obliteration. Six cases showed complete obliteration, and four partial obliterations were observed among ten cases, and interestingly, six cases of complete obliteration were observed among seven cases of small AVM of smaller than 3cm(the rate of complete obliteration : 85.7%). All patients tolerated the treatment and no significant complication were seen. Conclusion : In this study, linac based radiosurgery using PKRS onto arteriovenous malformation showed excellent effects, therefore authors believe that it is an ideal method for small sized or deep seated AVM.

• Progress in Medical Physics
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• v.24 no.4
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• pp.290-294
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• 2013

Stereotactic Radiosurgery require high accuracy and precision of patient positioning and target localization. We evaluate the real time positioning accuracy of isocenter using optic guided patient positioning system, ExacTrac (BrainLab, Germany), during spinal radiosurgery procedure. The system is based on real time detect multiple body markers attached on the selected patient skin landmarks. And a custom designed patient positioning verification tool (PPVT) was used to check the patient alignment and correct the patient repositioning before radiosurgery. In this study, We investigate the selected 8 metastatic spinal tumor cases. All type of tumors commonly closed to thoracic spinal code. To evaluate the isocenter positioning, real time patient alignment and positioning monitoring was carried out for comparing the current 3-dimensional position of markers with those of an initial reference positions. For a selected patient case, we have check the isocenter positioning per every 20 millisecond for 45 seconds during spinal radiosurgery. In this study, real time average isocenter positioning translation were $0.07{\pm}0.17$ mm, $0.11{\pm}0.18$ mm, $0.13{\pm}0.26$ mm, and $0.20{\pm}0.37$ mm in the x (lateral), y (longitudinal), z (vertical) directions and mean spatial error, respectively. And body rotations were $0.14{\pm}0.07^{\circ}$, $0.11{\pm}0.07^{\circ}$, $0.03{\pm}0.04^{\circ}$ in longitudinal, lateral, table directions and mean body rotation $0.20{\pm}0.11^{\circ}$, respectively. In this study, the maximum mean deviation of real time isocenter positioning translation during spinal radiosurgery was acceptable accuracy clinically.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.379-386
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• 2010

This study evaluated the motion of tumors during the entire period of therapy and the accuracy of radiosurgery among forty eight lung tumor patients who were underwent radiosurgery using the CyberKnife Synchrony Respiratory Tracking System. The motion of lung tumor was measured by the coordinates of a gold acupuncture needle inserted into the tumor or the area around the tumor using the CyberKnife image guided system. Then the accuracy of radiosurgery was evaluated based on the error of correlation computed with the motion tracking system. The lung tumor motion is Cranio-Caudal direction by an average of $2.63{\pm}1.87\;mm$, moved left-right direction by $1.13{\pm}0.71\;mm$, and anterior-posterior direction by $1.74{\pm}1.16\;mm$. The degree of rotational movement was $1.66{\pm}1.66^{\circ}$ on X axis, $1.20{\pm}0.97^{\circ}$ on Y axis, and $1.18{\pm}0.73^{\circ}$ on Z axis. The vector of translation movement was measured to be $3.78{\pm}2.00\;mm$ on the average. The results show that directions of Cranio-Caudal(p < 0.001), anterior-posterior direction(p < 0.029), and three dimensional vector value(p < 0.002) showed statistical significance, because the lower side of tumor showed more intensive movement compared to the upper side of tumor. The radiosurgery was carried out by compensating the motion of tumor after accurate investigation of the correlation error with the average of $0.95{\pm}0.62\;mm$ during the lung tumor radiosurgery with the CyberKnife Synchrony Respiratory Tracking System.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.801-809
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• 2019

Existing Gamma Knife Radiosurgery(GKRS) for large lesions is often conducted in stages with volume or dose partitions. Often in case of volume division the target used to be divided into sub-volumes which are irradiated under the determined prescription dose in multi-sessions separated by a day or two, 3~6 months. For the entire course of treatment, treatment informations of the previous stages needs to be reflected to subsequent sessions on the newly mounted stereotactic frame through coordinate transformation between sessions. However, it is practically difficult to implement the previous dose distributions with existing Gamma Knife system except in the same stereotactic space. The treatment area is expanding because it is possible to perform the multistage treatment using the latest Gamma Knife Platform(GKP). The purpose of this study is to introduce the image-coregistration based on the stereotactic spaces and the strategy of multistage GKRS such as the determination of prescription dose at each stage using new GKP. Usually in image-coregistration either surgically-embedded fiducials or internal anatomical landmarks are used to determine the transformation relationship. Author compared the accuracy of coordinate transformation between multi-sessions using four or six anatomical landmarks as an example using internal anatomical landmarks. Transformation matrix between two stereotactic spaces was determined using PseudoInverse or Singular Value Decomposition to minimize the discrepancy between measured and calculated coordinates. To evaluate the transformation accuracy, the difference between measured and transformed coordinates, i.e., ${\Delta}r$, was calculated using 10 landmarks. Four or six points among 10 landmarks were used to determine the coordinate transformation, and the rest were used to evaluate the approaching method. Each of the values of ${\Delta}r$ in two approaching methods ranged from 0.6 mm to 2.4 mm, from 0.17 mm to 0.57 mm. In addition, a method of determining the prescription dose to give the same effect as the treatment of the total lesion once in case of lesion splitting was suggested. The strategy of multistage treatment in the same stereotactic space is to design the treatment for the whole lesion first, and the whole treatment design shots are divided into shots of each stage treatment to construct shots of each stage and determine the appropriate prescription dose at each stage. In conclusion, author confirmed the accuracy of prescribing dose determination as a multistage treatment strategy and found that using as many internal landmarks as possible than using small landmarks to determine coordinate transformation between multi-sessions yielded better results. In the future, the proposed multistage treatment strategy will be a great contributor to the frameless fractionated treatment of several Gamma Knife Centers.

• Progress in Medical Physics
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• v.25 no.4
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• pp.281-287
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• 2014

The Winston Lutz test, which checks the accuracy of the isocenter for stereotactic radiosurgery (SRS), was performed with the commercial electronic portal imaging device (EPID). The usual Winston Lutz test with film was also performed for comparison with the test with EPID. The maximum difference in isocenter between the two methods was 0.32 mm. The Winston Lutz test using EPID is practical as it can reduce time and avoid human errors compared to the test with film.

• Journal of International Society for Simulation Surgery
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• v.2 no.2
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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.