• Korean Journal of Optics and Photonics
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• v.25 no.4
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• pp.200-206
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• 2014

In this paper, using the value theoretically calculated to emit multidirectionally a beam coming into an optical fiber with diameter of $125{\mu}m$, we modeled and produced a cone-shaped structure at the distal end of the fiber. A numerical simulation was performed for an optical fiber tip in which all incident beams were totally reflected and emitted toward the side, as well as for an optical fiber tip from which the beams could be emitted forward and sideways simultaneously. We produced multidirectional-firing optical fiber tips based on the simulation result and model. Laser fabrication of the optical fiber was done by processing a cone-shaped structure at the distal end of an optical fiber with diameter of $125{\mu}m$ using a femtosecond pulsed laser and polishing the processed surface with a $CO_2$ laser. We also conducted an analysis to compare experimental and simulation results.

• Radiation Oncology Journal
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• v.8 no.1
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• pp.111-114
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• 1990

External stereotaxic irradiation of intracranial lesions has recently gained its interest in the fields of not only radiation oncolgy but also neurosurgery. Its main goal is to deliver large doses to a relatively small target volume. Authors present methods of the stereotaxic radiosurgical irradiation using 6 MV linear accelerator (Nelac-6) and isodose distribution by therapeutic computer (Therac 2000). We attempt to demonstrate the dose distribution on verification films.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1017-1022
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• 2013

Currently, various optical fiber tips are used to deliver laser beam for endoscopic surgery. In this paper, we demonstrated multidirectional (forward and side) firing optical fiber tip using a femtosecond micromachining and $CO_2$ laser polishing technology. We controlled the edge width of optical fiber tip, by modulating the condition of $CO_2$ laser, to regulate the amount of side and forward emission. The distal end of the optical fiber with core/clad diameter of $400/440{\mu}m$ was microstructured with cone shape by using a femtosecond laser. And then the microstructured optical fiber tip was polished by $CO_2$ laser beam result in smoothing and specular reflection at the surface of the cone structure. Finally, we operated the LightTools simulation and good agreement was generally found between the proposed model and experimental simulation.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.53-58
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• 1991

From February 1987 through July 1990, the seventeen cases of inoperable intracranial arteriovenous malformation (AVM) were treated using 6 MV linear accelerator at the Division of Therapautic Radiology, Kang Nam 51. Mary's Hospital. Of seventeen cases, fourteen were male and three were female. Ages ranged from 10 to 51 years (median age of 25 years). The main symtoms were headache, epilepsy and hemiparesis in decreasing order of frequency. The middle cerebral artery is the most common origin of the feeding vessel $(41.2\%)$. Four were treated by conventionally fractionated radiation therapy (CRT, thirteen were treated by stereotactic radiosurgery (RS). duration or follow-up in CRT and RS group were 4 to 43 months (median 33 months) and 3 to 12 months (median 13 months), respectively. When the response was assessed by radiologic follow-up study, two of four CRT group showed minimal response. Of thirteen cases of RS group, two $(15.4\%)$ showed complete response, five $(38\%)$ partial response, two $(15.4\%)$ minimal response and four $(30.7\%)$ no response by the same assessment. There was no statistical significance in terms of follow-up period (p=0.22), size of lesion (p=0.82) and treated dose (p=0.05). Further accumulation of experience is recommended with proper case selection and sufficient follow-up period.