• Journal of Korean Neurosurgical Society
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• v.45 no.5
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• pp.275-283
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• 2009

Objective : We retrospectively analyzed survival, local control rate, and incidence of radiation toxicities after radiosurgery for recurrent metastatic brain lesions whose initial metastases were treated with whole-brain radiotherapy. Various radiotherapeutical indices were examined to suggest predictors of radiation-related neurological dysfunction. Methods : In 46 patients, total 100 of recurrent metastases (mean 2.2, ranged 1-10) were treated by CyberKnife radiosurgery at average dose of 23.1 Gy in 1 to 3 fractions. The median prior radiation dose was 32.7 Gy, the median time since radiation was 5.0 months, and the mean tumor volume was $12.4cm^3$. Side effects were expressed in terms of radiation therapy oncology group (RTOG) neurotoxicity criteria. Results : Mass reduction was observed in 30 patients (65%) on MRI. After the salvage treatment, one-year progression-free survival rate was 57% and median survival was 10 months. Age(<60 years) and tumor volume affected survival rate(p=0.03, each). Acute (${\leq}$1 month) toxicity was observed in 22% of patients, subacute and chronic (>6 months) toxicity occurred in 21 %, respectively. Less acute toxicity was observed with small tumors (<$10cm^3$. p=0.03), and less chronic toxicity occurred at lower cumulative doses (<100 Gy, p=0.004). "Radiation toxicity factor" (cumulative dose times tumor volume of <1,000 Gy${\times}cm^3$) was a significant predictor of both acute and chronic CNS toxicities. Conclusion: Salvage CyberKnife radiosurgery is effective for recurrent brain metastases in previously irradiated patients, but careful evaluation is advised in patients with large tumors and high cumulative radiation doses to avoid toxicity.

• Journal of Korean Neurosurgical Society
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• v.38 no.3
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• pp.184-189
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• 2005

Objective : Hemangioblastomas are highly vascular and benign neoplasm of the central nervous system[CNS]. They can often be found as multiple lesions, as is commonly observed in von Hippel-Lindau[VHL] disease. The aim of this study is to determine the proper management for multiple hemangioblastomas. Methods : Since 1990, 78cases of hemangioblastoma have been encountered. Among these, 9cases were multiple hemangioblastomas that were treated with surgical resection with or without radiosurgery. The medical, radiological, surgical and histological records were reviewed retrospectively and analyzed statistically. Results : Nine patients presented with multiple hemangioblastomas and were diagnosed as VHL disease. The mean follow-up duration was 75.7months [$6.6{\sim}159.2months$] after the first surgical treatment. Three patients were treated with surgical resection alone and six patients were treated by both surgical resection and radiosurgery. Twenty-one surgical procedures [13 surgical resections and 8 radiosurgery] were performed. One patient required ventriculoperitoneal shunt and a posterior fossa decompressive craniectomy because of post-radiation brain swelling. Another patient refused additional treatment for the newly developed lesions after the successful treatment of initial lesions. The other patient who presented with numerous lesions in the whole brain and spine underwent cranio-spinal irradiation. Remaining patients showed good results. Conclusion : The surgical outcomes for the patients with a single lesion of the CNS hemangioblastoma are favorable. However. the treatment of multiple hemangioblastoma is more difficult, and should be treated by surgical resection and radiosurgery with careful consideration.

• Journal of Korean Neurosurgical Society
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• v.67 no.4
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• pp.458-466
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• 2024

Objective : Several clinical studies have explored the feasibility and efficacy of radiosurgical treatment for mesial temporal lobe epilepsy, but the long-term safety of this treatment has not been fully characterized. This study aims to report and describe radiation-induced cavernous malformation as a delayed complication of radiosurgery in epilepsy patients. Methods : The series includes 20 patients with mesial temporal lobe epilepsy who underwent Gamma Knife radiosurgery (GKRS). The majority received a prescribed isodose of 24 Gy as an adjuvant treatment after anterior temporal lobectomy. Results : In this series, we identified radiation-induced cavernous malformation in three patients, resulting in a cumulative incidence of 18.4% (95% confidence interval, 6.3% to 47.0%) at an 8-year follow-up. These late sequelae of vascular malformation occurred between 6.9 and 7.6 years after GKRS, manifesting later than other delayed radiation-induced changes, such as radiation necrosis. Neurological symptoms attributed to intracranial hypertension were present in those three cases involving cavernous malformation. Of these, two cases, which initially exhibited an insufficient response to radiosurgery, ultimately demonstrated seizure remission following the successful microsurgical resection of the cavernous malformation. Conclusion : All things considered, the development of radiation-induced cavernous malformation is not uncommon in this population and should be acknowledged as a potential long-term complication. Microsurgical resection of cavernous malformation can be preferentially considered in cases where the initial seizure outcome after GKRS is unsatisfactory.

• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.58-60
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• 2006

Hypothalamic hamartoma[HH] is an unusual nonneoplastic developmental lesion associated with gelastic epilepsy and precocious puberty, mostly found in children. Although open surgery has been attempted when antiepileptic medication failed to control seizures, its deep location and surrounding vital structures often rendered surgery unsuccessful. We describe the outcome of gamma knife radiosurgery in three children with a HH associated with gelastic epilepsy and reviewed the literature for a possible therapeutic mechanism.

• 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.

• Progress in Medical Physics
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• v.24 no.3
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• pp.145-153
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• 2013

Stereotactic body radiation therapy (SBRT) is increasingly used to treat spinal metastases. To achieve the highest steep dose gradients and conformal dose distributions of target tumors, intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques are essential to spine radiosurgery. The purpose of the study was to qualitatively compare IMRT and VMAT techniques with International Spine Radiosurgery Consortium (ISRC) contoured consensus guidelines for target volume definition. Planning target volume (PTV) was categorized as TB, $T_{BPT}$ and $T_{ST}$ depending on sectors involved; $T_B$ (vertebral body only), $T_{BPT}$ (vertebral body+pedicle+transverse process), and $T_{ST}$ (spinous process+transverse process). Three patients treated for spinal tumor in the cervical, thoracic, and lumbar region were selected. Eacg tumor was contoured by the definition from the ISRC guideline. Maximum spinal cord dose were 12.46 Gy, 12.17 Gy and 11.36 Gy for $T_B$, $T_{BPT}$ and $T_{ST}$ sites, and 11.81 Gy, 12.19 Gy and 11.99 Gy for the IMRT, RA1 and RA2 techniques, respectively. Average fall-off dose distance from 90% to 50% isodose line for $T_B$, $T_{BPT}$, and $T_{ST}$ sites were 3.5 mm, 3.3 mm and 3.9 mm and 3.7 mm, 3.7 mm and 3.3 mm for the IMRT, RA1 and RA2 techniques, respectively. For the most complicated target $T_{BPT}$ sites in the cervical, thoracic and lumbar regions, the conformity index of the IMRT, RA1 and RA2 is 0.621, 0.761 and 0.817 and 0.755, 0.796 and 0.824 for rDHI. Both IMRT and VMAT techniques delivered high conformal dose distributions in spine stereotactic radiosurgery. However, if the target volume includes the vertebral body, pedicle, and transverse process, IMRT planning resulted in insufficient conformity index, compared to VMAT planning. Nevertheless, IMRT technique was more effective in reducing the maximum spinal cord dose compared to RA1 and RA2 techniques at most sites.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.137-145
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• 1992

Three-dimensional dose calculations based on CT images are fundamental to stereotactic radiosurgery for small intracranial tumor. In our stereotactic radiosurgery program, irradiations have been performed using the 6 MV photon beam of linear accelerator after stereotactic CT investigations of the target center through the beam's-eye view and the coordinates of BRW frame converted to that of radiosurgery. Also we can describe the tumor diameter and the shape in three dimensional configuration. Non-coplanar irradiation technique was developed that it consists of a combination of a moving field with a gantry angle of $140^{\circ}$, and a horizontal couch angle of $200^{\circ}C$ around the isocenter. In this radiosurgery technique, we provide the patient head setup in the base-ring holder and rotate around body axis. The total gantry moving range shows angle of 2520 degrees via two different types of gantry movement in a plane perpendicular to the axis of patient. The 3-D isodose curves overlapped to the tumor contours in screen and analytic dose profiles in calculation area were provided to calculate the thickness of $80\%$ of tumor center dose to $20\%$ of that. Furtheremore we provided the 3-D dose profiles in entire calculation plane. In this experiments, measured isodose curves in phantom irradiation have shown very similiar to that of computer generations.

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.43-48
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• 1999

Purpose : For practical application of the MR image for stereotactic radiosurgery, the target point achieved by acquisition of MR image in a relatively homogeneous phantom has to agree with the actual isocenter of irradiation in real radiosurgery and the amount of distortion of the MR image should be known. Materials and Methods : A dosimetric film with a random target point was inserted into a radish vertically and horizontally on axis Z and they were fixed with a headring. After image acquisition by stereotactic radiosurgery planning system, we achieved stereotactic coordinate of the target point and examined irradiation using the coordinate acquired as isocenter. After the irradiation, the film in the radish was developed and processed and the degree of coincidence between the target point marked on the film and the center of the radiation distribution. In order to measure the degree of distortion of the MR image in a different way, an acryl phantom was made and punctures were made at intervals of 1 cm and a drop of oil was dropped into it. Then, it was inserted into the radish vertically and horizontally on axis Z to acquire the MR image. Each coordinate was achieved and the estimation of distortion of MR image was made both in vertical and horizontal directions Results : The film from the radio was developed and for the one inserted vertically on axis Z, there was a good coincidence in the discrepancy between the target point marked on the film and the center of the radiation distribution. For the one inserted horizontally, the discrepancy between them was under 0.5 mm. As a result of estimating distortion of MR image using acryl, the discrepancy was under 0.45 mm in the case of the phantom inserted vertically on axis Z, and that of the one inserted horizontally was 1.4 mm. Conclusion : We were able to confirm good coincidence in homogeneous phantom in actual treatment position of radiosurgery using the MR image and the discrepancy measured in the analysis of distortion of the MR image did not exceed the permissible level. Therefore, it was evident the system of the hospital is suitable for radiosurgery using MR image.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.128-129
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• 2011

• 대한방사선치료학회:학술대회논문집
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• 1996.06a
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• pp.6-6
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• 1996