• 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 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.

• 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.

• 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.

• 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.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.3
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• pp.1-13
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• 2009

Objectives : This study evaluates neuroprotective effect of Gastrodiae Rhizoma on apoptosis in the cerebral infarct. Methods : Cerebral infarct was induced by the middle cerebral artery occlusion (MCAO) for 2 hours with intraluminal thread method in Sprague-Dawley rats. Then ethanol extract of Gastrodiae Rhizoma was administered orally for 3 days. Infarct area and volume were evaluated with TTC staining. Neuronal apoptosis was identified with TUNEL labeling. Apoptosis modulatory effect was observed with immunohistochemical Bax, Bcl-2, iNOS, and MMP-9 expressions in penumbra. Results : 1. Ethanol extract of Gastrodiae Rhizoma reduced infarct size partly and volume significantly of in the MCAO rat brain. 2. Ethanol extract of Gastrodiae Rhizoma reduced TUNEL positive cell ratio in the penumbra of MCAO rat brain significantly. 3. Ethanol extract of Gastrodiae Rhizoma suppressed Bax, iNOS and MMP-9 expression in the penumbra of MCAO rat brain significantly. 4. Ethanol extract of Gastrodiae Rhizoma did not change Bcl-2 expression in the penumbra of MCAO rat brain. But expression ratio of Bcl-2 against Bax was increased in the Gastrodiae Rhizoma group. Conclusions : These results suggest that Gastrodiae Rhizoma plays an anti-apoptotic neuroprotective effect through suppression of Bax, iNOS, and MMP-9 expressions and relative up-regulation of Bcl-2 in the ischemic brain tissue.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.1
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• pp.47-51
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• 2010

Purpose: In the treatment of high-energy protons Air gap (the distance between the patient and the exit Beam) Lateral Penumbra of the changes to the increase in the radiation fields can form unnecessary and Increase the maximum dose at the site of treatment and reduced the minimum dose homogeneity of dose distributions can decline. Air gap due to this change in dose distribution compared to investigate studied. Materials and Methods: Received proton therapy at our institution Lung, Liver patients were selected and the size of six other Air gap in Field A and Field B 2, 4, 6, 8, 10 cm Proton external beam planning system by setting up a treatment plan established. Air gap according to the Lateral Penumbra area and DVH (Dose Volume Histogram) to compare the maximum dose and minimum dose of PCTV areas were compared. In addition, the dose homogeneity within PCTV Homogeneity index to know the value and compared. Results: Air gap (2, 4, 6, 8, 10 cm) at each change in field size were analyzed according to the Lateral Penumbra region Field A Change in the Air gap 2~10 cm by 1.36~1.75 cm, the average continuously increased about 28.7% and Field B Change in the Air gap 2~10 cm by 1.36~1.75 cm, the average continuously increased about 31.6%. The result of DVH analysis for relative dose of the maximum dose According to Air gap 2~10 cm is the mean average of 110.3% from 108.1% to a sustained increased by approximately 2.03% and The average relative dose of minimum dose is the mean average of 93.9% percent to 90.8 percent from the continuous decrease of about 3.31 percent. The result of Homogeneity index value to the according to Air gap 2~10 cm is the 2-fold increase from 1.09 to 2.6. Conclusion: In proton therapy case, we can see the increasing of lateral penumbra area when airgap getting increase. And increasing of Dmax and decreasing Dmin in the field are making increase homogeneity index, So we can realize there are not so good homogeneity in the PCTV. Therefore we should try to minimize air gap in proton therapy case.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.1-9
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• 2004

Purpose : The aim of this study is to investigate the properties of small field size and to measure the penumbra and central axis depth dose varying to the jaw setting and off axis distance for indicate this data to small field sizes radiation therapy. Material and methods : The percentage depth dose, beam profile and central axis output dose was measured by farmer type ion chamber and pinpoint chamber using Primart linac with 6MV energy. Beam quality and penumbra variations according to the central axis shift, from center to every 2cm outside increment, and field size, from $1{\times}1cm$ to $10{\times}10cm$ was investigated and compared with that of the standard geometrical condition's results Results : The differences of measured values between two ion chamber was about $37\%$ at 10cm depth with $1{\times}1cm$ field sizes but as field size increased this differences was diminished gradually. Measured data from various off axis distance with the different asymmetric collimations are not changed significantly but as size decreased the dose variation was increased and at $1{\times}1cm$ field size dose difference among off axis distance was as much as $13\%$, and as shallower the measured depth the central axis dose variations among the OAD was increased, penumbra was not changed noticeably depending on off axis distance but the percentage of penumbra from its initial field sizes was strongly dependant on field sizes and penumbra occupation rates of its own field sizes ranging from $6\%$ at $10{\times}10cm$ to $50\%$ at $1{\times}1cm$ field size. Conclusion : For imrt treatment, there are several numbers of different gentry angles with beams of nonuniform fluences are required and several complex factors involved. Among them the characteristics of beam output varying to the geometrical setting and design of collimators are of important to attaining a good treatment results. As mentioned in results the differences of measured values are changed significantly depends on ion chamber volume, depths and field size. For providing quality radiation treatment, especially at small field size, those factor's should have considering deliberately.

• Journal of radiological science and technology
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• v.8 no.2
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• pp.71-72
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• 1985

This study was performed on the dose distribution of various field size and the effect of penumbra shield in the telecobalt unit. The results obtained are as follows. 1. Errors of the light and ${\gamma}-ray$ field size was below the regulation as 0.52 percentage. 2. The coefficient of field area was increased with the larger field area, and this coefficient was showed the more difference in larger SSD. 3. The rectangular field areas, which were described by level of the same percentage depth does, were decreased with the more elongation factor. At the same elongation factor, the compensating factor was decreased with the larger field size. 4. The lead block or extension collimator was able to shield r-ray exposure of outside field size from 50 to 80 percentage. 5. On the matching adjacent fields, while the gap between beam edges are contacted, that overlapped beam edges indicated up to 140 percentage, and while the gap was 1 cm, it could be reduced to 90 Percentage. The lead-libocking on the overlapped area was more effective to lower dose, as 80 percentage in this case. 6. Percentage depth dose of various trimming field sizes were increased linearlly according to area 1 perimeter size, but the center split field size did not maintain linearlly.