• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.103-105
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• 2002

Whole body stereotactic radiosurgery (WBSRS) technique is believed to be useful for the metastatic lesions as well as relatively small primary tumors in the trunk. Unlike stereotactic radiosurgery to intracranial lesion, inherent limitation on immobilization of whole body makes it difficult to achieve the reliable setup reproducibility. For this reason, it is essential to develop an objective and quantitative method of evaluating setup error for WBSRS. An evaluation technique using image registration has been developed for this purpose. Point pair image registrations with WBSRS frame coordinates were performed between two sets of CT images acquired before each treatment. Positional displacements could be determined by means of volumetric planning target volume (PTV) comparison between the reference and the registered image sets. Twenty eight sets of CT images from 19 WBSRS patients treated in Asan Medical Center have been analyzed by this method for determination of setup random error of each treatment. It is objective and clinically useful to analyze setup error quantitatively by image registration technique with WBSRS frame coordinates.

• The Journal of Korean Society for Radiation Therapy
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• v.6 no.1
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• pp.146-153
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• 1994

A modified irradiation technique utilizing a linear accelerator for radiation surgery within the brain was performed in 41 cases of patients with anteriovenous malformation(AVM), astrocytoma, meningioma. etc. The treatment planning and dosimetry of small field for stereotactic radiosurgery with 10 MV X-ray isocentically mounted linear accelerator will be presented dose with field size, the central axis persent depth dose and the combined moving beam dose distribution. The three dimensional dose planning of stereotactic focusing irradiation on small size tumor region was perfomed with dose planning computer system(Therac 2300) and was verified with film dosimetry. The more the number of strip and the wider the angle of arc rotation, the larger were the dose delivered on tumor and the less the dose to surrounding the normal tissues. In this study, the using machine and method was as fellowing. 1) Apparatus : NELAC-1018 10MV X-ray 2) Strip No. : Select the 5-7 strips 3) Cone and field size are from $1{\times}1cm^2$ to $3.5{\times}3.5cm^2$, and special circular cone designed for the purpose of minimized the risk to normal tissue and those size are $0.7{\~}3.6cm{\phi}$.

• Journal of Korean Neurosurgical Society
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• v.58 no.3
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• pp.217-224
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• 2015

Objective : To investigate the efficacy and safety of fractionated stereotactic radiosurgery for large brain metastases (BMs). Methods : Between June 2011 and December 2013, a total of 38 large BMs >3.0 cm in 37 patients were treated with fractionated Cyberknife radiosurgery. These patients comprised 16 men (43.2%) and 21 women, with a median age of 60 years (range, 38-75 years). BMs originated from the lung (n=19, 51.4%), the gastrointestinal tract (n=10, 27.0%), the breast (n=5, 13.5%), and other tissues (n=3, 8.1%). The median tumor volume was 17.6 cc (range, 9.4-49.6 cc). For Cyberknife treatment, a median peripheral dose of 35 Gy (range, 30-41 Gy) was delivered in 3 to 5 fractions. Results : With a median follow-up of 10 months (range, 1-37 months), the crude local tumor control (LTC) rate was 86.8% and the estimated LTC rates at 12 and 24 months were 87.0% and 65.2%, respectively. The median overall survival (OS) and progression-free survival (PFS) rates were 16 and 11 months, respectively. The estimated OS and PFS rates at 6, 12, and 18 months were 81.1% and 65.5%, 56.8% and 44.9%, and 40.7% and 25.7%, respectively. Patient performance status and preoperative focal neurologic deficits improved in 20 of 35 (57.1%) and 12 of 17 patients (70.6%), respectively. Radiation necrosis with a toxicity grade of 2 or 3 occurred in 6 lesions (15.8%). Conclusion : These results suggest a promising role of fractionated stereotactic radiosurgery in treating large BMs in terms of both efficacy and safety.

• Progress in Medical Physics
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• v.12 no.2
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• pp.171-175
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• 2001

We analyze the relation of dose volume histogram, conformity index and homogeneity index based on RTOG9005 for treatment planning result between framed based stereotactic radiosurgery(SRS) system and frameless SRS/T system to verify the difference of two systems in the intracranial target. There is same treatment planning result by two treatment planning systems.

• Journal of Korean Neurosurgical Society
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• v.61 no.4
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• pp.525-529
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• 2018

Objective : To evaluate the efficacy of fractionated stereotactic radiosurgery (FSRS) performed using the Novalis $Tx^{(R)}$ system (BrainLAB AG, Feldkirchen, Germany; Varian Medical Systems, Palo Alto, CA, USA) for brain metastases. Methods : Between March 2013 and July 2016, 23 brain metastases patients were admitted at a single institute. Twenty-nine lesions too large for single session stereotactic radiosurgery or located in the vicinity of eloquent structures were treated by FSRS. Based on the results obtained, we reviewed the efficacy and toxicity of FSRS for the treatment of brain metastases. Results : The most common lesion origin was lung (55%) followed by breast (21%). Median overall survival was 10.0 months (95% confidence interval [CI], 4.9-15.0), and median progression-free survival was 10.0 months (95% CI, 2.1-13.9). Overall survival rates at 1 and 2 years were 58.6% and 36.0%, respectively. Local recurrence and neurological complications affecting morbidity each occurred in two cases. Conclusion : FSRS using the $Novalis-Tx^{(R)}$ system would appear to be an effective, safe noninvasive treatment modality for large and eloquently situated brain metastases. Further investigation is required on a larger number of patients.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7595-7597
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• 2015

Background: The aim of this study was to evaluate the effect of whole brain radiotherapy (WBRT) combined with streotactic radiosurgery versus stereotactic radiosurgery (SRS) alone for patients with brain metastases. Materials and Methods: This was a retrospective study that evaluated the results of 46 patients treated for brain metastases at Dr. Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital, Radiation Oncology Department, between January 2012 and January 2015. Twenty-four patients were treated with WBRT+SRS while 22 patients were treated with only SRS. Results: Time to local recurrence was 9.7 months in the WBRT+SRS arm and 8.3 months in SRS arm, the difference not being statistically significant (p=0.7). Local recurrence rate was higher in the SRS alone arm but again without significance (p=0,06). Conclusions: In selected patient group with limited number (one to four) of brain metastases SRS alone can be considered as a treatment option and WBRT may be omitted in the initial treatment.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3271-3276
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• 2016

Background: Intracranial nonvestibular schwannomas arising from various cranial nerves excluding CN VIII are uncommon. Recently, stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) have been widely reported as effective treatment modalities for nonvestibular schwannomas. The purpose of this study was to study the long term clinical outcome for nonvestibular schwannomas treated with both X-Knife and CyberKnife (CK) radiosurgery at one institution. Materials and Methods: From 2004 to 2013, fifty-two nonvestibular schwannoma patients were included in this study, 33 patients (63%) were treated with CK, and 19 (37%) were treated with X-Knife. The majority of the tumors were jugular foramen schwannomas (38%) and trigeminal schwannomas (27%). HSRT was given for 45 patients (86%), whereas CSRT was for 6 (12%) and SRS for 1 (2%). Results: The median pretreatment volume was $9.4cm^3$ (range, $0.57-52cm^3$). With the median follow up time of 36 months (range, 3-135), the 3 and 5 year progression free survival was 94 % and 88%, respectively. Tumor size was decreased in 13 (25%), stable in 29 (56%), and increased in 10 (19%). Among the latter, 3 (30%) required additional treatment because of neurologic deterioration. No patient was found to develop any new cranial nerve deficit after SRS/SRT. Conclusions: These data confirmed that SRS/SRT provide high tumor control rates with low complications. Large volume tumors and cystic expansion after radiation should be carefully followed up with neurological examination and MRI, because it may frequently cause neurological deterioration requiring further surgery.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2005.04a
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• pp.47-50
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• 2005

The aim of radiosurgery cures a patient to deliver the lower dose at the normal organ and the higher dose at the tumor. Therefore accuracy of the dose is required to gain effect of radiosurgery in surgical planning. In this paper, we developed the methods of target approximation for a fast treatment planning. Nominally, the stereotactic radiosurgery(SRS) using Linac and Gamma knife produces spherical dose distribution through circular collimators using multiple arcs and 201 holes on semi-spherical helmet by $^{60}Co$. We developed an automatic radiosurgical plan about spherical packing arrangement. To automatically plan the SRS, new planning methods based on cylinder and cube structure for target shaping was developed. This approach using heuristic and stochastic algorithm is a useful radiosurgical plan without restrictions in the various tumor shapes and the different modalities.

• The Journal of Korean Society for Radiation Therapy
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• v.12 no.1
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• pp.20-25
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• 2000

The accuracy of the target localization was evaluated by conventional and spiral CT in stereotactic radiosurgerv. Conventional and spiral CT images were obtained with geometrical phantom, which was designed to produce exact three-dimensional coordinates of several objects within 0.1mm error range. Geometrical phantom was attached by BRW headframe, intermediate head ring, and CT localizer. Twentv-seven slices of conventional CT image were scanned at 3 mm slice thickness. Spiral CT images were scanned at 3 mm slice thickness from the pitch value 1 to 3, and twenty-seven slices of image were obtained per each the pitch value. These CT images were transferred to a treatment planning system(X-knife, Radionics) by ethernet, Three-dimensional coordinates of these images measured from the treatment planning system were compared to known values of geometrical phantom. The mean localization error of the target localization of conventional CT was 1.4mm. In case of spiral CT, the error of the target localization was within 1.6mm from the pitch value 1 to 1.3, but was more than 30mm above the pitch value 1.5. In conclusion, as the localization error of spiral CT was increased in high pitch value compared to conventional CT, the application of spiral CT will be with caution in stereotactic radiosurgery.

• Journal of Radiation Protection and Research
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• v.20 no.1
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• pp.25-36
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• 1995

The purpose of this research is to develop stereotactic localization and radiation measurement system for the efficient and precise radiosurgery. The algorithm to obtain a 3-D stereotactic coordinates of the target has been developed using a Fisher CT or angio localization. The procedure of stereotactic localization was programmed with PC computer, and consists of three steps: (1) transferring patient images into PC; (2) marking the position of target and reference points of the localizer from the patient image; (3) computing the stereotactic 3-D coordinates of target associated with position information of localizer. Coordinate transformation was quickly done on a real time base. The difference of coordinates computed from between Angio and CT localization method was within 2 mm, which could be generally accepted for the reliability of the localization system developed. We measured dose distribution in small fields of NEC 6 MVX linear accelerator using various detector; ion chamber, film, diode. Specific quantities measured include output factor, percent depth dose (PDD), tissue maximum ratio (TMR), off-axis ratio (OAR). There was small variation of measured data according to the different kinds of detectors used. The overall trends of measured beam data were similar enough to rely on our measurement. The measurement was performed with the use of hand-made spherical water phantom and film for standard arc set-up. We obtained the dose distribution as we expected. In conclusion, PC-based 3-D stereotactic localization system was developed to determine the stereotactic coordinate of the target. A convenient technique for the small field measurement was demonstrated. Those methods will be much helpful for the stereotactic radiosurgery.