• 대한방사선치료학회지
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• 제10권1호
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• pp.69-77
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• 1998

When a high energy photon beam is used to treat lesions located in the upper respiratory air passages or in maxillary sinus, the beams often must traverse an air cavity before it reaches the lesion. Because of this traversal of air, it is not clear that the surface layers of the lesion forming the air-tumor tissue interface will be in a state of near electronic equilibrium; if they are not, underdosing of these layers could result. Although dose corrections at large distances beyond an air cavity are accountable by attenuation differences, perturbations at air-tissue interfaces are complex to measure or calculate. This problem has been investigated for 4MV and 10MV X-ray beams which are becoming widely available for radiotherapy with linear accelerator. Markus chamber was used for measurement with variouse air cavity geometries in X-ray beams. Underdosing effects occur at both the distal and proximal air cavity interface. The magnitude depended on geometry, energy, field sizes and distance from the air-tissue interfaces. As the cavity thickness increased, the central axis dose at the distal interface decreased. Increasing field size remedied the underdosing, as did the introduction of lateral walls. Fellowing a $20{\times}2{\times}2\;cm^3$\;air\;cavity,\;4{\times}4\;cm\;field\;there\;was\;an\;11.5\%\;and\;13\%\;underdose\;at\;the\;distal\;interface,\;while\;a\;20{\times}20{\times}2\;cm^3\;air\;cavity\;yielded\;a\;24\%\;and\;29\%$ loss for the 4MV and 10MV beams, respectively. The losses were slightly larger for the 10MV beams. The measurements reported here can be used to guide the development of new calculation models under non-equilibrium conditions. This situation is of clinical concern when lesions such as larynx and maxillary carcinoma beyond air cavities are irradiated.

• Radiation Oncology Journal
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• 제13권4호
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• pp.397-402
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• 1995

Purpose : To determine the perturbation effect in the tissue downstream from surface layers of lesions located in the air/tumor-tissue interface of larynx using 6MV photon beam. Materials and Methods : Thermoluminescent dosimeters(TLDs), were embedded at 3 measurement locations in slab no. 7 of a humanoid phantom and exposed to forward and backward direction using various field sizes($4{\times}4cm^2\;-\;15{\times}15cm^2$). Results : At the air/tissue interface, forward dose perturbation factor(FDPF) is about 1.085 with $4{\times}4cm^2,\;1.05\;with\;7{\times}7cm^2,\;1.048\;with\;10{\times}10cm^2$ and $1.041\;with\;15{\times}15cm^2$. Backscatter dose perturbation factor(BDPF) is about 0.99 with $4{\times}4cm^2$, 0.981 with $7{\times}7cm^2$, 0.956 with $10{\times}10cm^2$ and 0.97 with $15{\times}15cm^2$. Conclusion : FDPF is greater as field size is smaller. And FDPF is smaller as the distance is further from the air/tissue interface.

• Radiation Oncology Journal
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• 제13권3호
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• pp.277-283
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• 1995

목적 : 임상 방사선치료에서 병소선량은 인체 연부조직의 방사선흡수와 유사한 수조펜텀에서 측정환산된 흡수선량자료를 이용하여 얻어지고 있으며, 방사선 치료부위내 공기층 또는 밀도가 낮은 폐조직 주위에 종양이 존재할 경우 공기층과 만나는 종양의 경계면 선량은 rebuild-up에 의해 낮아질 수 있으나 현재까지 연구 발표된 것은 많지 않다. 이에 본 연구에서는 6, 10 메가볼트 광자선을 이용하여 조직 불균질층 경계면 선량을 실험적으로 측정하여 종양선량에 미치는 영향을 분석하여 방사선 치료선량 결정에 이용하고자 하였다. 방법 : 고에너지 광자선의 조사면내 조직 불균질성에 의한 선량변화를 얻기 위하여 조직층에 해당되는 폴리스티렌 고체펜텀의 두께가 각각 10, 30, 50 mm 인 경우 공기층의 두께를 10, 20, 30, 50 mm 로 변화시켜서, 이러한 조직층과 공기층을 지나 종양의 가장자리에 해당되는 수조펜텀의 표면에 도달되는 방사선량을 평행평판형전리함으로 측정하였다. 방사선 조사면적은 임상에서 비교적 많이 이용되는 $5{\times}5,\;10{\times}10,\;20{\times}20\;cm^2$를 사용하였다. 결과 : 방사선 조사면적 $5{\times}5\;cm^2$ 이고 조직층 두께 30 mm 일때 6 메가볼트 광자선에서 공기층 두께변화에 따른 표면선량 변화는 표준선량보다 공기층 10 mm 에서는 $1.1\%$, 50 mm 에서는 $29.1\;\%$ 낮아졌으며 공기층 두께가 두꺼워질수록 방사선량 감소가 현저했다. 같은 조건에서 10 메가볼트 광자선에서 선량변화는 표준선량보다 $4.2\%$에서 $33.9\%$ 까지 낮아졌다. 동일 깊이에서 표준심부선량에 대한 불균질 조직층 선량의 비인 OER 은 조사면적 10{\times}10\;cm^2$ 이상에서는 1 보다 크거나 1 에 가까운 값을 보였다. 결론 : 방사선 조사면적이 커지면 공기층과 인접한 조직 경계면의 선량감소는 거의 나타나지 않으며, $10{\times}10\;cm^2$ 이하의 소조사면 치료시 조직 경계면의 종양에 대한 치료선량 평가에는 rebuild-up 효과를 고려하여야 될 것으로 생각된다. 임상에서 6 메가볼트 광자선을 사용하여 공기층이 존재하는 구강과 인후두 종양을 치료할 때, 공기층에 인접한 점막층 (1-3 mm) 의 선량은 표준선량에 비해 $29\%$ 까지 적게 도달될 수 있으므로 방사선 치료선량 결정에 이러한 곁과를 필히 고려하여야 될 것으로 사료된다.

• 대한방사선치료학회지
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• 제20권1호
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• pp.1-9
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• 2008

목 적: 두 경부 암 방사선치료 시 구강 구조물 내에 정확한 자세 재현성을 유지하는 것은 환자에게 편안함을 주는 동시에 최적화된 선량분포를 얻는데 매우 중요하다. 이 연구의 목적은 방사선치료 시 재현성을 유지하고 구강 내부의 공기와 조직계면 사이의 선량을 보정하기 위해 각 환자의 고정 기구를 자체 제작하였으며, 이를 기존의 고정 기구와 비교 분석하는데 그 목적이 있다. 대상 및 방법: 치과 환자의 구강 조형물 제작 시 사용되는 알지네이트(alginate; AROMA FINE DF III normal set, japan)와 퍼티 (putty; aquasil soft putty/regular set, germany)를 이용하여 각 환자의 구강 구조와 동일한 고정 기구를 제작 하였다. 방사선 치료 시 재현성을 평가를 위해 자체 제작한 고정 기구를 이용하여 컴퓨터 단층 촬영 시와 동일한 자세로 5회 Linac-gram을 촬영하고 분석하였다. 자체 제작한 고정 기구의 선량 안정성을 검증하기 위하여 공기, 물, 알지네이트 그리고 퍼티를 삽입할 수 있는 아크릴 팬텀을 제작하였다. 실험은 두 가지 조사면적(3$\times$3 cm, 5$\times$5 cm)에 대해 단일 조사를 통해 이루어졌고 방사선 치료 계획 장비(Pinnacle ver.7.6c, Philips, USA)에 의해 계산된 선량과 EBT 필름을 사용한 측정된 선량을 비교 분석하였다. 결 과: 자체 제작한 고정 기구의 재현성 검증을 위한 조사야 확인 영상 확인 결과 기존의 고정 기구를 사용한 경우에 비해 알지네이트와 퍼티를 이용한 고정 기구는 4배 이상의 우수한 재현성을 보였고, 방사선 치료 시 환자의 불편함을 해소 할 수 있었다. 방사선 치료 계획 장비를 이용한 계산된 계면선량은 공기일 때 3$\times$3 cm, 5$\times$5 cm에서 각각 7.87%, 0.56%로 나타났으며 EBT (international specialty products, USA)필름을 사용한 측정된 계면선량은 36.5%, 11.8%로 EBT 필름을 사용한 측정된 계면선량이 크게 나타났다. 결 론: 두 경부 암 환자의 방사선 치료 시 구강 내 구조물의 자세 재현성을 유지하기 위하여 알지네이트와 퍼티를 이용하여 자체 제작한 고정 기구는 기존의 고정 기구 보다 매우 우수한 재현성을 유지 할 수 있었으며, 소 조사면에 대한 방사선 치료 계획 시 치료 계획 장비의 선량 계산 알고리즘의 한계로 인한 구강 내 계면선량의 감소를 보정해 최적의 선량분포를 얻을 수 있었다.

• Radiation Oncology Journal
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• 제7권1호
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• pp.113-121
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• 1989

The inclusion of air filled cavities in treatment fields creates a potential dosimetric problem due to the rebuildup phenomenon near the air-tissue interface using a simulated phantom, such as air gap, air cylinder, and air cavity, the amount of rebuldup along the various field sizes and air cavity dimensions was measured. The results are as follows. 1. As the field size becomes larger in comparison with the cavity size, or as the cavity size gets bigger when the field size is equal to the cavity size, rebuildup decreases. 2. When the distance between the phantom surface and the air cavity is less than 1.5cm, there is prominent rebuildup. And when the distance is more than 1.5cm, rebuildup is relatively constant, 3. The change according to the depth of the cavity is affected by the field size and the cavity size, rebuildup usually increases when the depth of the cavity increases. 4. It is suggested that tissue equivalent material should be applied on the skin to make tissue thickness over the air cavity more than 1.5cm and that the field size should include the air cavity with at least 1cm margin.

• 대한화장품학회지
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• 제29권2호
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• pp.105-130
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• 2003

Human skin equivalents, also designated as cultured skin substitute (Boyce and Warden, 2002) or organotypic co-cultures (Maas-Szabowski et al., 1999, 2000, 2003), are three-dimensional systems that are engineered by seeding fibroblasts into a three-dimensional dermal matrix. Such a dermal equivalent is then subsequently seeded with human keratinocytes. After cell attachment, the culture is kept first under submerged condition to allow keratinocyte proliferation. Thereafter, the culture is lifted the air-liquid interface (A/L) to expose the epidermal compartment to the air, and to further induce keratinocyte differentiation. During the air-exposure, nutrients from the medium will diffuse through the underlying dermal substrate towards the epidermal compartment and support keratinocyte proliferation and differentiation. Under these conditions, a HSE is formed that shows high similarity with the native tissue from which it was derived (Figure 1) (Bell et at., 1981; Boyce et al., 1988; Ponec et al., 1997;El Ghalbzouri et al.., 2002).

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.463-486
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• 1995

The effect of moistening and air-drying of acid-conditioned dentin before priming on the formation of resin-dentin hybrid zone was investigated, Freshly extracted human molars were used and divided at random into 5 groups, Groups 1 - 3 consisted of specimens conditioned with 10 % phosphoric acid for 20 seconds; Group 1 served as a control in which the conditioned dentin was simply blot-dried with a damp facial tissue; Group 2 was air dried for 30 seconds ; Group 3 was air dried for 30 seconds and immediately remoistened for 10 seconds with air-water syringe. and then the specimen was blot-dried with a damp facial tissue. Groups 4-5 were not acid conditioned ; In group 4, the smear layer on the dentin was blot dried before primer placement; Group 5 was air dried only for 30 seconds, The acetone-based primer and bonding agent of All Bond 2 (Bisco. Inc., USA) and composite resin (Z-100, 3M Dental products, USA) were applied for acid conditioned dentin and non-conditioned dentin. The morphologic ultrastructure of resin-dentin hybrid zone was examined by the use of SEM and TEM. and the existence of inorganic material and analysis of Ca/P weight-percent ratio in the resin-dentin hybrid zone were revealed by the EDAX, The results were as follows : 1. In the moistened specimens from acid-conditioned groups, the resin penetrated about 3-$4{\mu}m$ into dentin and the denatured collagen smear layer was not present at the surface. The resin tag was formed to a thickeness of 3-$4{\mu}m$ at the upper part of dentinal tubule and compactively connected to each other by means of many lateral branching. 2. In the air-dried specimens from acid-conditioned groups, the resin penetrated about 2.0-$2.5\;{\mu}m$ into dentin and an upper thin black layer to a thickness of 30-35nm was identified between adhesive resin and demineralized collagen layer. The resin tag to have a diameter of $2.5{\mu}m$ was formed at the upper part of dentinal tubule. However the funnel shape of the tag was not notable compared to the moistened specimens. 3. In the remoistened specimens from acid conditioned groups, the resin penetrated about 2.0-$2.5{\mu}m$ into dentin and an upper black layer was not present. The resin tag at the upper part of dentinal tubule was formed less than $2{\mu}m$ and was weakly connected to each other by means of few lateral branching. 4. In the non-conditioned groups, the smear layer was formed to a thickness of $0.5{\mu}m$ at dentin surface. However, the resin-dentin hybrid zone was not identified by TEM. The evidence of resin penetration into intertubular and intratubular dentin did not show. 5. All the acid-conditioned groups showed that the detected calcium and phosphorus weight percent ratios at the $2{\mu}m$ upper portion from the resin-dentin interface into the resin were much higher than that at the $2{\mu}m$ lower portion from the resin-dentin interface to dentin. (P<0.01).

• 대한인간공학회지
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• 제29권4호
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• pp.639-646
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• 2010

The APAM's quantitative effectiveness and comparative study in preventing and treating pressure ulcer has not been sufficiently evaluated mainly because of uncertainty of pressure load input and lack of interpretation of dynamic perfusion recovery characteristics of soft tissue. The purpose of this paper was to quantify and analyze the alternating pressure characteristics of APAM as a preventive measure for pressure ulcers. To quantify the alternating load to human body, we introduced alternating pressure profile concept and developed parametric model of the profile. Regarding pressure level and cycle time, 3 global and 7 local periodic parameters were used to define the profile such as light, standard, typical and heavy duty profile shape. Pressure impulse ratio of light duty is the lowest but pressure fluctuation is significantly high. For the same duty shape, contact conditions are changed with alternating cycle time and more dramatically in shorter alternating cycle time conditions. We can conclude that if we use shorter alternating cycle time on APAM's operation we can get more positive effects regarding to inflated contact time condition. We proposed the quantitative methods on tissue viability study of external loading by simultaneous measurement of interface pressure and tissue perfusion with proper alternating pressure profile conditions.

• Journal of Pharmaceutical Investigation
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• 제40권6호
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• pp.321-332
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• 2010

Growing interest in the nasal route as a drug delivery system calls for a reliable in vitro model which is crucial for efficiently evaluating drug transport through the nasal cells. Various in vitro cell culture systems has thus been developed to displace the ex vivo excised nasal tissue and in vivo animal models. Due to species difference, results from animal studies are not sufficient for estimating the drug absorption kinetics in humans. However, the difficulty in obtaining reliable human tissue source limits the use of primary culture of human nasal epithelial cells. This shortage of human nasal tissue has therefore prompted studies on the "passage" culture of nasal epithelial cells. A serially passaged primary human nasal epithelial cell monolayer system developed by the air-liquid interface (ALI) culture is known to promote the differentiation of cilia and mucin gene and maintain high TEER values. Recent studies on the in vitro nasal cell culture systems for drug transport studies are reviewed in this article.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.14-17
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• 1995

An in vitro construct of three dimensional artificial skin equivalent has been engineered using human cervical epithelial cells and human foreskin fibroblasts with a matrix of bovine type I collagen. Two cell lines were established from cervical uteri cancer tissues which have the HPV(human papillomavirus)18 genome. These two cell lines came from the same origin but have slight differencies in growth rate and tumorigenicity. The organotypic raft culturing of epithelial cells were accomplished at air-liquid interface. The differentiation related characteristics were examined by immunohistochemistry using monoclonal antibodies against EGFreceptor, cytokeratin 5/6/18 as proliferation markers and against filaggrin, involucrin, and cytokeratin 10/13 as differentiation marker. We have obtained the stratification and the differentiation in the artificial skin equivalent, and differentiation-related proteins were expressed more in the C3-artificial skin, and proteins of proliferation were expressed more in the C3N-artificial skin, relatively. We found that reconstituted artificial skin have the same characteristics of differentiation proteins of original tissue or cells of human body.