• Progress in Medical Physics
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• v.25 no.1
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• pp.37-45
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• 2014

The accuracy and uniformity of CT numbers are the main causes of radiation dose calculation error. Especially, for the dose calculation based on kV-Cone Beam Computed Tomography (CBCT) image, the scatter affecting the CT number is known to be quite different by the object sizes, densities, exposure conditions, and so on. In this study, the scatter impact on the CBCT based dose calculation was evaluated to provide the optimal condition minimizing the error. The CBCT images was acquired under three scatter conditions ("Under-scatter", "Over-scatter", and "Full-scatter") by adjusting amount of scatter materials around a electron density phantom (CIRS062, Tissue Simulation Technology, Norfolk, VA, USA). The CT number uniformities of CBCT images for water-equivalent materials of the phantom were assessed, and the location dependency, either "inner" or "outer" parts of the phantom, was also evaluated. The electron density correction curves were derived from CBCT images of the electron density phantom in each scatter condition. The electron density correction curves were applied to calculate the CBCT based doses, which were compared with the dose based on Fan Beam Computed Tomography (FBCT). Also, 5 prostate IMRT cases were enrolled to assess the accuracy of dose based on CBCT images using gamma index analysis and relative dose differences. As the CT number histogram of phantom CBCT images for water equivalent materials was fitted with a gaussian function, the FHWM (146 HU) for "Full-scatter" condition was the smallest among the FHWM for the three conditions (685 HU for "under scatter" and 264 HU for "over scatter"). Also, the variance of CT numbers was the smallest for the same ingredients located in the center and periphery of the phantom in the "Full-scatter" condition. The dose distributions calculated with FBCT and CBCT images compared in a gamma index evaluation of 1%/3 mm criteria and in the dose difference. With the electron density correction acquired in the same scatter condition, the CBCT based dose calculations tended to be the most accurate. In 5 prostate cases in which the mean equivalent diameter was 27.2 cm, the averaged gamma pass rate was 98% and the dose difference confirmed to be less than 2% (average 0.2%, ranged from -1.3% to 1.6%) with the electron density correction of the "Full-scatter" condition. The accuracy of CBCT based dose calculation could be confirmed that closely related to the CT number uniformity and to the similarity of the scatter conditions for the electron density correction curve and CBCT image. In pelvic cases, the most accurate dose calculation was achievable in the application of the electron density curves of the "Full-scatter" condition.

• 한국노년학
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• v.31 no.3
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• pp.831-848
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• 2011

The purpose of this study is to analyse the family caregivers' stress pathways by types of long term care services for the elderly, and then to discuss the findings of analysis. For this research, primary caregivers that provide care the elderly requiring long term care services sanctioned by National Health Insurance Corporation were drawn and surveyed. Among collected data, data for 258 primary caregivers by type of long term care services were used for this study. The results of this study can be summarized as follows. First, on average, the elders that utilize care service in institutions for the elderly were higher proportion of women, older, higher rate of bereavement, more children than the elders that utilize in-home care service, but some cases were vice-versa. Second, the elders that utilize care service in institutions more ADL dependency, higher proportion of severe dementia or severe stroke, higher care rank by National Health Insurance Corporation than the elders that utilize in-home care service on average. Third, primary caregivers with elders that utilize in-home care service were higher proportion of women, older, lower education level, higher rate of spouse and daughter-in-law in relationship with care recipient, less health, lower income than primary caregivers with elders that utilize care service in institutions. Fourth, subjective indicators representing caregivers' reactions to caregiving for the elderly significantly impact on caregivers' stress(ie, depression), and pathway of caregivers' stress are differentiated by type of long term care services. Fifth, stressors that have direct impacts on depression as caregiving family are differentiated by type of long term care services. Therefore, policies or programs to reduce negative mental health or stress of caregivig families should be designed differently by reflecting pathway of various stressors and stress by use types of long term care services for the elderly.

• 한국노년학
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• v.30 no.4
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• pp.1359-1375
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• 2010

Expecting the expansion of the elderly population under long-term home care with the coming of the aged society, this study purposed to propose a prevention and self-reliance support model and to get practical implications for minimizing dependency on care benefits and enhancing the effectiveness of prevention and self-reliance support. Research methods employed for this study were: first, reviewing theoretical literature for clarifying the concept of prevention and self-reliance support in providing long-term care benefits for the elderly; second, identifying factors hindering prevention and self-reliance support through analyzing standard long-term care use plans and documents related to long-term care benefits at elderly welfare centers to which the research subjects belonged; and third, surveying care benefit users on factors hindering their use of prevention and self-reliance support and their needs in the use of care benefits. Based on the results of the three types of qualitative research, we proposed directions for prevention and self-reliance support modeling and suggested practical implications for enhancing the effectiveness of prevention and self-reliance support. For this study, we collected documentary materials and conducted in-depth interviews with the participants with the consents and cooperation of managers and professional social workers at day care centers and elderly welfare centers in D City. According to the results of this study, literature review suggested that long-term care prevention and self-reliance support should be provided in a way of 'strengthening user-centered support systems,' which support elderly long-term care beneficiaries' right to lead a life as the subject of their own life. Document analysis found the absence of benefits related to health and medicine and lack of social support systems for prevention and self-reliance support, and the results of in-depth interviews suggested the necessity to strengthen services related to elderly long-term care beneficiaries' prevention and self-reliance, and the keen needs of the long-term care elders for prevention and self-reliance included: ① loneliness, anxiety, fear; ② missing for and worry about children and people; ③ moving, outing; ④ health and medical services, rehabilitation programs; ⑤ desire to use day care; ⑥ inconvenience of house structure; ⑦desire for meal menus; and ⑧ the occurrence of disuse syndrome. Based on these results, we suggested the base of prevention and self-reliance support modeling with three axes: ① strengthening user-centered support systems; ② strengthening support systems connected to health and medicine; and ③ strengthening social support systems.

• 한국노년학
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• v.29 no.4
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• pp.1559-1575
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• 2009

As the basic old-age pension system was enforced in 2008, the base for old-age income security was founded. However, due to the basic old-age pension played a minor role as assistant allowance, it did not reach to sufficient level to cover full income security system. It is estimated that the dependency on private transfer income among the elderly who are difficult to be economically independent is still high. Therefore the poverty rate of the elderly households, who are not economically active or who are not protected by old-age income security system, is more likely to be higher than that of non-elderly households. Based on the assumption that public transfer income system should become a central means of old-age life guarantee, this study examined the poverty mitigation effects among the elderly households by comparing the private transfer income and the public transfer income. For this purpose, we selected single-elderly-households who have been considered the most vulnerable to poverty. We used 2006- 2008 Household Income and Expenditure Survey dataset that contained single-elderly who were older than 65 years old. To understand the conditions of poverty among single-elderly-households and the degree of poverty-reducing effect originated from income transfer system, we compared the poverty rates of total households and the whole elderly households. Next, we analysed the poverty of the single-elderly-households by social demographic factors such as gender, age, and economic activity. Our major findings are as follows: First, the poverty rate of the whole elderly households were not reduced, even though the basic old-age pension and long-term care management system were enforced in 2008. Second, half of the elderly households including single-elderly-households belonged to the absolute poverty line. Relatively higher level of poverty among the single-elderly-households was found especially those who were female, unemployed, low-educated, older, and rural single-elderly-households. Third, the effect of the public transfer income on mitigating the single-elderly-households poverty showed a little progress. However, even greater poverty reducing effect was found by the private transfer income system. Fourth, in a group of the public transfer systems, the public assistance such as supporting living costs contributed more to reduce poverty of the elderly population than the public pension system did.