• The Journal of Internal Korean Medicine
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• v.21 no.2
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• pp.341-348
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• 2000

I have treated one ischemic stroke patient in acute stage with Seonghyangjeonggi-san, and observed remarkable reduction of the size ischemic portion in brain CT, notable improved motor power of patient. So I report this case of stroke patint. The ischemic penumbra, simply stated, is the part of the brain that is sandwiched brain regions committed to die and those that receive enough blood to communicate. Therefore, it is ischemic brain tissue that has just enough to communicte and function. The life expectancy of the penumbrais short. Although the penumbra is an elegant concept, in practice, it has been a difficult one to exploit. Up to now, a lot of research worker have tried to develop the method to make a accurate diagnosis. and then we know that PET and Xenon CT is available for the diagnosis for the ischemic penumbra. But those are not perfect to diagnose of penumbra. The case in my case report was confirmed as ischemic penumbra with CT. I know that CT is not prefect to diagnose penumbra, but I just want to raise the interest in penumbra of oriental medicine researcher and my report will be benificial to the penumbra researcher.

• The Journal of Korean Society for Radiation Therapy
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• v.6 no.1
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• pp.84-88
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• 1994

Proper evaluation about the penumbra is very important to improve the efficacy of radiation theraphy. There are two kinds of physical penumbra, geometric penumbra and transmission penumbra. In this study, we evaluated the variation of physical penumbra according to the varing enery level, changing the field size and depth. Physical penumbra width was decreased as the source size decreased, and as the SDD increased, but the consideration about the scatter radiation and mechanical stability is an important factor. For the two adjacent beams, upper collimator should be used and especially for Co-60 unit, it is efficient to use the extended collimator.

• Journal of radiological science and technology
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• v.16 no.2
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• pp.81-86
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• 1993

Proper evaluation about the penumbra is very important to improve the efficacy of radiation theraphy. There are two kinds of physical penumbra, geometric penumbra and transmission penumbra. In this study, we evaluated the variation of physical penumbra according to the varing energy level, changing the field size and depth. Physical penumbra width was decreased as the source size decreased, and as the SDD increased, but the consideration about the scatter radiation and mechanical stability is an important factor. For the two adjacent beams, upper collimator should be used and especially for Co-60 unit, it is efficient to use the extended collimator.

• Nuclear Engineering and Technology
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• v.5 no.2
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• pp.87-93
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• 1973

Due to the Co-60 source size, the penumbra in Co-60 teletheraphy poses a serious problem, even if the extended collimators are used, Here an empirical formula for the calculation of integral absorbed dose in the penumbra region was derived. Through a numerical calculation, the penumbra effect on integral absorbed dose was investigated. The longer the source-to-skin distance, the larger the integral absorbed dose of penumbra region, and the larger the source diameter, the larger the integral absorbed dose of penumbra region. It was also found that in some case the integral absorbed dose in penumbra region becomes several times larger than the integral absorbed dose of treatment region itself if the source-to-skin distance becomes greater. Therefore, one must consider the penumbra effect in Co-60 teletherapy.

• Radiation Oncology Journal
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• v.9 no.2
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• pp.333-336
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• 1991

High energy Photon beam has a sharp beam margin due to a less side scatter and the other things. But there still remains a penumbra where the dose changes rapidly in the region near the edge of a radiation beam, although it is short in width. It is suggested that the width of the penumbra depends on the source size, distance from source to diaphragm, source to skin distance, and depth in tissue. However, it is also supposed that the other factors influence the penumbra width. In this paper, we investigate changes of the physical penumbra widths according to various field sizes and depths, by using the three dimensional dosimetry system. As a result, we found that as field size and depth increase, the physical penumbra width also increases.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.65.2-65.2
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• 2013

A presence of a penumbra is one of the main properties of a mature sunspot, and its formation mechanism has been elusive due to a lack of observations that fully cover the formation process. Utilizing the New Solar Telescope at the Big Bear Solar Observatory, we observed the formation of a partial penumbra for about 7 hours simultaneously at the photospheric (TiO; $7057{\AA}$) and the chromospheric ($H{\alpha}$, $-1{\AA}$) spectral lines with high spatial and temporal resolution. From this uninterrupted, long observational sequence, we found that flux emergence under the stable chromospheric canopy fields resulted in penumbra formation, while emerging flux under the expanding chromospheric fields appeared as transient elongated granules. Based on these findings, we suggest a possible scenario for penumbra formation in which a penumbra forms when the emerging flux is constrained from continuing to emerge, but rather is trapped at the photospheric level by the overlying chromospheric canopy fields.

• The Journal of Korean Society for Radiation Therapy
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• v.10 no.1
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• pp.88-93
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• 1998

Multileaf collimator is essential equipment in conformal radiation therapy, however the use is limitted by increase of penumbra width and undulating dose distribution at the field edge. The purpose of this study is to improve the penumbra and dose distribution in the multileaf collimator field edge. Measurement were performed with X-omat V film in solid water phantom using 6MV photon beam from Siemens linear accelerator. All the measurement were made along the central axis of $5{\times}5cm,\;10{\times}10cm$ circular field for constant SSD of 100 cm. To improve the penumbra and dose distribution collimator was rotated by 15 degrees from 0 to 90 degrees (collimator rotation method) and center was shifted to the longitudinal direction by fourth of lead width (center shift method). We compare the penumbra and dose distribution at the field edge to alloy block. Dose distribution and penumbra width at the feild edge of MLC showed undulated dose pattern and increased penumbra compared with alloy block. However, in the collimator rotation method and center shift method we abtained simular results with alloy block. Through the study we expected that clinical use of MLC will be increase.

• Radiation Oncology Journal
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• v.14 no.4
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• pp.333-338
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• 1996

Purpose : To evaluate the clinical implications of scallop penumbra width that comes from multileaf collimator(MLC) effect by the daily routine patient setup error. Materials and Methods : The anales of $0^{circ},{\;}15^{circ},{\;}30^{circ},{\;}45^{circ},{\;}60^{circ},{\;}and{\;}75^{circ}$ inclined -radiation blocked fields were generated using the both conventional cerrobend block and the MLC. Film dosimetry in the phantom were performed to measure penumbral widths of differences between the dose distributions from the cerrobend block and those of respect the MLC. The patient setup error effect on scallop penumbra was simulated with respect to the table of setup error distribution. Same procedures are repeated for the cerrobend block generated field. Results : There are penumbral widths of to 3mm difference between the dose distributioins from two kinds of field shaping tools, the conventional block and the MLC with 4mm setup error model and resolution of 1cm leaf at the isocenter. Conclusion : We need not additive margin for MLC, if planning target volume is selected according to the recommendation of ICRU 50. For particular cases, we can include the target volume with less than 3mm additive margin.

• Journal of Korean Neurosurgical Society
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• v.38 no.4
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• pp.293-298
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• 2005

Objective : The authors investigate the spatial characteristics of apoptotic genes expressed around the focal cerebral infarction, and attempted to explain the penumbra with them. Methods : A delayed focal cerebral infarction was created in twelve adult Sprague-Dawley rats. We performed the immunohistochemical staining for the apoptosis, bcl-2 and p53 proteins and measured the local cerebral blood flow [CBF] at the infarction core area and peri-infarct area pre- and intra-operatively. The peri-infarct area was divided into six sectors by distance from the infarction border. Results : The size [$mm^2$] of apoptosis, bcl-2, and p53 areas were $3.1{\pm}1.2$, $4.7{\pm}2.1$, and $6.8{\pm}2.4$, respectively. Apoptosis, bcl-2 or p53 positive cells were concentrated at the peri-infarct area adjacent to the infarction core. Their numbers reduced peripherally, which was inversely proportional to the local CBF. The p53 area seems to overlap with and larger than the ischemic penumbra. Conclusion : The p53 positive area provides a substitutive method defining the penumbra under the molecular base of knowledge.

• Radiation Oncology Journal
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• v.13 no.4
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• pp.391-396
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• 1995

Purpose : The Conformal Radiation Therapy has bee widely used under favour of development of computer technologies. The delivery of a large number of static radiation fields are being necessary for the conformal irradiation. In this paper we investigate dosimetric characteristics on penumbra regions of a multileaf collimator(MLC), and compare to those of lead alloy block for the optimal use of the system in 3-D conformal radiotherapy. Materials and Methods : The measurement of penumbra by MLC or lead alloy block was performed with 6 or 10 MV X-rays. The film was positioned at a dmax depth and 10 cm depth, and its optical density was determined using a scanning videodensitometer. The effective penumbra, the distance from $80{\%}$ to $20{\%}$ isodose lines and $90{\%}$ to $10{\%}$ were analyzed as a function of the angle between the direction of leaf motion and the edge defined by leaves. Results : Increasing MLC angle ($0-75^{\circ}$) was observed with increasing the penumbra widths and the scalloping effect. There was no definite differences of penumbra width from $80{\%}$ to $20{\%}$ isodose lines, while being the small increase of penumbra width from $90{\%}$ to $10{\%}$ isodose line varing the depth and energy. The effective penumbra width of lead alloy block are agree resonably with those of MLC within 4.8mm. Conclusion : The comparative qualitative study of the penumbra between MLC and lead alloy block demonstrate the clinical acceptability and suitability of the multileaf collimator for 3-D conformal radiotherapy.