1.Extracranial Doses with LIINAC Stereotactic Radiosurgery.
Charn Il PARK ; Wee Saing KANG ; Sung Whan HA ; Young Kap CHO ; II Han KIM
Journal of the Korean Society for Therapeutic Radiology 1996;14(2):159-166
No astract is available
Radiosurgery*
2.Measurement of Dosimetric Parameters and Dose Verifi cation in Stereotactic Radiosurgery (SRS)
Reduan Abdullah ; Nik Ruzman Nik Idris ; Ahmad Zakaria ; Ahmad Lutfi Yusof ; Mazurawati Mohamed ; Nur Iziana Mohsin
Malaysian Journal of Health Sciences 2015;13(1):39-49
The fi rst part of this study was about measurement of dosimetric parameters for small photon beams to be used as input
data for treatment planning computer system (TPS) and to verify the dose calculated by TPS in Stereotactic Radiosurgery
(SRS) procedure. The beam data required were percentage depth dose (PDD), off-axis ratio (OAR) and scattering factor.
Small beams of 5 mm to 45 mm diameter from a circular cone collimator in SRS were used for beam data measurements.
Measurements were made using pinpoint ionisation chamber (0.016cc). In the second part of this study, we reported
the important of carrying out quality assurance (QA) procedures before SRS treatment which were found to infl uence the
accuracy of dose delivery. These QA procedures consisted of measurements on the accuracy in target localization and
treatment room laser alignment. The calculated TPS dose for treatment was verifi ed using pinpoint ionisation chamber
and thermoluminescent detector (TLD) 100H. The deviation mean between measured and calculated dose was -3.28%.
The measured dose obtained from pinpoint ionisation chamber is in good agreement with the calculated dose from TPS
with deviation mean of 2.17%. In conclusion, pinpoint ionisation chamber gives a better accuracy in dose calculation
compared to TLD 100H. The results are acceptable as recommended by International Commission on Radiation Units
and Measurements (ICRU) Report No. 50 (1994) that dose delivered to the target volume must be within ± 5% error.
Radiosurgery
3.De novo cavernous malformation after radiosurgery for cerebellar arteriovenous malformation: A case report
Sang Heum Kim ; Tae Gon Kim ; Min Ho Kong
Neurology Asia 2017;22(3):261-266
Stereotactic radiosurgery, including gamma knife radiosurgery (GKS), can in rare cases result in
de novo cavernous malformations (CMs). Here, we present a case of de novo CM induced by GKS
following treatment of a cerebellar arteriovenous malformation (AVM). A 48-year-old woman was
diagnosed with left unilateral Moyamoya disease. Conventional cerebral angiography also revealed an
AVM in the left cerebellum. The patient underwent GKS using a 50% isodose of 15 Gy at the margin
of the left cerebellar AVM. Magnetic resonance imaging (MRI) taken 3 years after GKS revealed
small chronic hemorrhages with perilesional edema in the left cerebellum. Five years later, the lesions
became aggravated, but were asymptomatic. Eight years following GKS, the patient was admitted
complaining of headache and dizziness. Brain MRI revealed a 1.3cm hemosiderin deposit with an
inner hyperintense nodular portion that was enhanced in the left cerebellum. An open craniotomy was
performed and the mass was removed, from which pathological findings were compatible with those
for CM. The patient recovered to the prehemorrhagic state. This case shows that De novo CMs can
rarely develop after radiosurgery. Most CMs have been reported to develop following radiosurgery
for brain tumors. As shown in this patient, CMs can also develop after radiosurgery for cerebellar
AVM in adults.
Radiosurgery
4.Gamma Knife Radiosurgery for Juxtasellar Tumors.
Jong Hee CHANG ; Jin Woo CHANG ; Yong Gou PARK ; Sang Sup CHUNG
Journal of Korean Neurosurgical Society 2000;29(10):1345-1351
No abstract available.
Radiosurgery*
5.Gamma Knife Radiosurgery on Uveal Melanoma.
Byung Wook KIM ; Moo Seong KIM ; Hong Bo SIM ; Yeong Gyun JEONG ; Sun Il LEE ; Yong Tae JUNG ; Soo Chun KIM ; Jae Hong SIM ; Il Han YOUN ; Young Il KIM ; Koang Ook PAIK
Journal of Korean Neurosurgical Society 2001;30(5):652-656
Uveal melanoma is uncommon but life-threatening intraocular malignancy and has been treated by irradiation, local excision and enucleation. Gamma-Knife radiosurgery allows a high dose of radiation to be delivered to an intracranial target with a very high spatial accuracy and has been used for the treatment of ocular melanomas. We have treated two cases of uveal melanoma between October 1994 and December 1999. They include one man and one woman(34, 62 years, respectively). They were followed up for 12 momths. Mean maximal dose was 65Gy. In one case, the tumor disappeared 7 months after gamma-knife radiosurgery. In another case, multiple tumors (uveal, suprasellar and cerebellar tumor) had decreased in size. These results show that single and high dose gamma-knife radiosurgery is may be an option in the local control of uveal melanoma which can spare the eyeball and vision.
Melanoma*
;
Radiosurgery*
6.Rapid Optimization of Multiple Isocenters Using Computer Search for Linear Accelerator-based Stereotactic Radiosurgery.
Tae Suk SUH ; Charn Il PARK ; Sung Whan HA ; Sei Chul YOON ; Moon Chart KIM ; Yong Whee BAHK ; Kyung Sub SHINN
Journal of the Korean Society for Therapeutic Radiology 1994;12(1):109-116
The purpose of this paper is to develop an efficient method for the quick determination of multiple isocenters plans to provide optimal dose distribution in stereotactic radiosurgery. A Spherical dose model was developed through the use of fit to the exact dose data calculated in a 18cm diameter of spherical head phantom. It computes dose quickly for each spherical part and is useful to estimate dose distribution for multiple isocenter. An automatic computer search algorithm was developed using the relationship between the isocenter move and the change of dose shape, and adapted with a spherical dose model to determine isocenter separation and collimator sizes quickly and automatically. A spherical dose model shows a comparable isodose distribution with exact dose data and permits rapid calculation of 3-D isodoses. The computer search can provide reasonable isocenter settings more quickly than trial and error types of plans, while producing steep dose gradient around target boundary. A spherical dose model can be used for the quick determination of the multiple isocenter plans with a computer automatic search. Our guideline is useful to determine the initial multiple isocenter plans.
Head
;
Radiosurgery*
7.Stereotactic LINAC Radiosurgery of Meningiomas.
Kyung Sik RYU ; Byung Chul SON ; Moon Chan KIM ; Tae Suk SUH ; Chul Seung KAY ; Sei Chul YOON ; Joon Ki KANG
Journal of Korean Neurosurgical Society 2000;29(3):317-323
No abstract available.
Meningioma*
;
Radiosurgery*
8.Estimation of Inhomogeneity Correction Factor in Small Field Dosimetry.
Hun Joo SHIN ; Young Nam KANG ; Jisun JANG ; Jae Hyuk SEO ; Ji Young JUNG ; Byung Ock CHOI ; Ihl Bohng CHOI ; Dong Joon LEE ; Soo Il KWON
Korean Journal of Medical Physics 2009;20(4):260-268
In this study, we estimated inhomogeneity correction factor in small field. And, we evaluated accuracy of treatment planning and measurement data which applied inhomogeneity correction factor or not. We developed the Inhomogeneity Correction Phantom (ICP) for insertion of inhomogeneity materials. The inhomogeneity materials were 12 types in each different electron density. This phantom is able to adapt the EBT film and 0.125 cc ion chamber for measurement of dose distribution and point dose. We evaluated comparison of planning and measurement data using ICP. When we applied to inhomogeneity correction factor or not, the average difference was 1.63% and 10.05% in each plan and film measurement data. And, the average difference of dose distribution was 10.09% in each measurement film. And the average difference of point dose was 0.43% and 2.09% in each plan and measurement data. In conclusion, if we did not apply the inhomogeneity correction factor in small field, it shows more great difference in measurement data. The planning system using this study shows good result for correction of inhomogeneity materials. In radiosurgery using small field, we should be correct the inhomogeneity correction factor, more exactly.
Electrons
;
Radiosurgery
9.Commissioning of a micro-MLC (mMLC) for Stereotactic Radiosurgery.
Dong Hyeok JEONG ; Kyo Chul SHIN ; Jeung Kee KIM ; Soo Kon KIM ; Sun Rock MOON ; Kang Kyoo LEE
Korean Journal of Medical Physics 2009;20(1):43-50
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.
Radiosurgery
;
Silver Sulfadiazine
;
Water
10.Confirmation of the Dose Distribution by Stereotactic Radiosurgery Technique with a Multi-purpose Phantom.
Hyung Jun YOO ; Il Han KIM ; Sung Whan HA ; Charn Il PARK ; Sun Nyung HUR ; Wee Saing KANG
The Journal of the Korean Society for Therapeutic Radiology and Oncology 2002;20(2):179-185
PURPOSE: For the purpose of quality assurance of self-developed stereotactic radiosurgery system, a multi-purpose phantom was fabricated, and accuracy of radiation dose distribution during radiosurgery was measured using this phantom. MATERIALS AND METHODS: A farmer chamber, a 0.125 cc ion chamber and a diode detector were used for the dosimetry. Six MV x-ray from a linear accelerator (CL2100C, Varian) with stereotactic radiosurgery technique (Green Knife) was used, and multi-purpose phantom was attached to a stereotactic frame (Fisher type). Dosimetry was done by combinations of locations of the detectors in the phantom, fixed or arc beams, gantry angles (20 ~100 ), and size of the circular tertiary collimators (inner diameters of 10 degrees~40 degrees mm). RESULTS: The measurement error was less than 0.5% by Farmer chamber, 0.5% for 0.125 cc ion chamber, and less than 2% for diode detector for the fixed beam, single arc beam, and 5-arc beam setup. CONCLUSION: We confirmed the accuracy of dose distribution with the radiosurgery system developed in our institute and the data from this study would be able to be effectively used for the improvement of quality assurance of stereotactic radiosurgery or fractionated stereotactic radiotherapy system.
Particle Accelerators
;
Radiosurgery*
;
Radiotherapy