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1.
Med Phys ; 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31732963

RESUMO

PURPOSE: The purpose of this study was to study the field size effect on the estimated Relative Biological Effectiveness (RBE) for carbon scanning beam irradiation. METHODS: A silicon-on-insulator (SOI) microdosimeter system developed by the Centre for Medical Radiation Physics, University of Wollongong, Australia, was used for lineal-energy measurements (microdosimetric quantity). The RBE values were derived based on the modified microdosimetric kinetic model (MKM) at different depths in a water phantom in the scanning carbon beam for various scanned areas. RESULTS: Our study shows that the difference in RBE values derived from the SOI microdosimeter measurements with the MKM model and from the Treatment Planning System (TPS). The difference of the RBE values is within 6.5 % at the peak point of the spread-out Bragg Peak (SOBP) region. Compared to the spot-beam, RBE values obtained in the scanned-beam with a larger scanned area of 1.0 × 1.0 cm2 have better agreement with which estimated by the TPS. CONCLUSIONS: This study shows the possibility of using the SOI microdosimeter system as a quality assurance (QA) tool for RBE evaluation in carbon-pencil beam scanning radiotherapy.

2.
Environ Sci Pollut Res Int ; 26(18): 18913-18920, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31102216

RESUMO

The ecosystem of the Seocheon coastal wetland (SCW), one of the wetland protected areas in South Korea, was registered in the Ramsar Wetlands in 2009 as an area rich in biodiversity and inhabited by endangered wild animals and plants. Since then, preserving the ecosystem of the SCW has emerged as an important task. Thus, the South Korean government is carrying out various research and management projects to preserve the ecological integrity of the SCW. This article aims to analyze public willingness to pay for preserving the SCW. For this purpose, 1000 households were surveyed, applying the contingent valuation (CV) method during September 2017. The respondents clearly understood the CV question and gave meaningful answers. The results show that an average value for the preservation was statistically significantly estimated to be KRW 2341 (USD 2.04) for all respondents. The national value expanded from the sample to the population is worth KRW 47.79 billion (USD 42.15 million) per year. Therefore, it can be seen that the public have sufficient acceptance for preserving the SCW.


Assuntos
Conservação dos Recursos Naturais/métodos , Política Ambiental , Áreas Alagadas , Animais , Biodiversidade , Ecologia , República da Coreia , Inquéritos e Questionários
3.
Environ Sci Pollut Res Int ; 26(11): 11503-11507, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30887453

RESUMO

Combined heat and power (CHP), which produces both heat and electricity at the same time, is so efficient that it can reduce energy use and emit less carbon dioxide (CO2) than conventional fossil fuel use. This article attempts to look empirically into the impact of CHP share in total electricity generation on CO2 emissions in a cross-country context. Data from 35 countries during the period 2009-2015 are used. For this purpose, the variable of CO2 emissions is regressed on three variables of constant, gross domestic product, and CHP share using two robust estimators. The results show that the level of CHP share of a country affects the level of its CO2 emissions negatively. That is, CHP leads to less CO2 emissions.


Assuntos
Poluentes Atmosféricos/análise , Dióxido de Carbono/análise , Conservação dos Recursos Naturais , Desenvolvimento Econômico , Centrais Elétricas , Conservação dos Recursos Naturais/economia , Países Desenvolvidos , Países em Desenvolvimento , Eletricidade , Combustíveis Fósseis , Temperatura Alta , Centrais Elétricas/economia
4.
Environ Sci Pollut Res Int ; 25(17): 17216-17222, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29777497

RESUMO

Korean government has made and will continue to make a considerable investment in contaminated soil remediation to rectify the problems that arise from soil pollution. Quantitative information on the benefits of contaminated soil remediation is widely demanded by the public as well as the government. This article aims to assess the external benefits of contaminated soil remediation. A survey of 1000 randomly selected households was undertaken in Korea. The results show that the marginal willingness to pay values for a 1% decrease in human health hazard, a 1% improvement in biodiversity restoration, and 1000 new job creation by contaminated soil remediation are estimated to be KRW 204 (USD 0.17), 593 (0.50), and 238 (0.20) per household per year. The findings can provide policy-makers with useful information for both evaluating and planning the contaminated soil remediation.


Assuntos
Poluição Ambiental/análise , Recuperação e Remediação Ambiental/métodos , Biodiversidade , Humanos , República da Coreia
5.
Oncotarget ; 8(68): 112390-112400, 2017 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-29348833

RESUMO

The purpose of this study was to investigate the potential of gold nanoparticles as radiosensitizer for use in neutron therapy against hepatocellular carcinoma. The hepatocellular carcinoma cells lines Huh7 and HepG2 were irradiated with γ and neutron radiation in the presence or absence of gold nanoparticles. Effects were evaluated by transmission electron microscopy, cell survival, cell cycle, DNA damage, migration, and invasiveness. Gold nanoparticles significantly enhanced the radiosensitivity of Huh7 and HepG2 cells to γ-rays by 1.41- and 1.16-fold, respectively, and by 1.80- and 1.35-fold to neutron radiation, which has high linear energy transfer. Accordingly, exposure to neutron radiation in the presence of gold nanoparticles induced cell cycle arrest, DNA damage, and cell death to a significantly higher extent, and suppressed cell migration and invasiveness more robustly. These effects are presumably due to the ability of gold nanoparticles to amplify the effective dose from neutron radiation more efficiently. The data suggest that gold nanoparticles may be clinically useful in combination therapy against hepatocellular carcinoma by enhancing the toxicity of radiation with high linear energy transfer.

6.
Oncotarget ; 7(40): 65125-65136, 2016 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-27556184

RESUMO

Treatment with alternating electric fields at an intermediate frequency (100-300 kHz), referred to as tumor treating fields (TTF) therapy, inhibits cancer cell proliferation. In the present study, we demonstrated that TTF application suppressed the metastatic potential of U87 and U373 glioblastoma cell lines via the NF-kB, MAPK and PI3K/AKT signaling pathways. Wound-healing and transwell assays showed that TTF suppressed cell migration and invasion compared with controls. Soft agar and three-dimensional culture assays showed that TTF inhibited both anchorage-dependent (cell proliferation) and anchorage-independent (colony formation) GBM cell growth. TTF dysregulated epithelial-to-mesenchymal transition-related genes, such as vimentin and E-cadherin, which partially accounted for TTF inhibition of cell migration and invasion. We further demonstrated that TTF application suppressed angiogenesis by downregulating VEGF, HIF1α and matrix metalloproteinases 2 and 9. TTF also inhibited NF-kB transcriptional activity. Collectively, our findings show that TTF represents a promising novel anti-invasion and anti-angiogenesis therapeutic strategy for use in GBM patients.


Assuntos
Movimento Celular/efeitos da radiação , Terapia por Estimulação Elétrica , Glioblastoma/patologia , Neovascularização Patológica , Linhagem Celular Tumoral , Radiação Eletromagnética , Humanos , Invasividade Neoplásica/patologia
7.
Oncotarget ; 7(38): 62267-62279, 2016 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-27556699

RESUMO

Alternating electric fields at an intermediate frequency (100~300 kHz), referred to as tumour-treating fields (TTF), are believed to interrupt the process of mitosis via apoptosis and to act as an inhibitor of cell proliferation. Although the existence of an antimitotic effect of TTF is widely known, the proposed apoptotic mechanism of TTF on cell function and the efficacy of TTF are controversial issues among medical experts. To resolve these controversial issues, a better understanding of the underlying molecular mechanisms of TTF on cell function and the differences between the effects of TTF alone and in combination with other treatment techniques is essential. Here, we report experimental evidence of TTF-induced apoptosis and the synergistic antimitotic effect of TTF in combination with ionizing radiation (IR). For these experiments, two human Glioblastoma multiforme (GBM) cells (U373 and U87) were treated either with TTF alone or with TTF followed by ionizing radiation (IR). Cell apoptosis, DNA damage, and mitotic abnormalities were quantified after the application of TTF, and their percentages were markedly increased when TTF was combined with IR. Our experimental results also suggested that TTF combined with IR synergistically suppressed both cell migration and invasion, based on the inhibition of MMP-9 and vimentin.


Assuntos
Apoptose/efeitos da radiação , Neoplasias Encefálicas/terapia , Movimento Celular/efeitos da radiação , Proliferação de Células/efeitos da radiação , Terapia por Estimulação Elétrica/métodos , Glioblastoma/terapia , Mitose/efeitos da radiação , Radioterapia/métodos , Linhagem Celular Tumoral , Terapia Combinada/métodos , Humanos , Imuno-Histoquímica , Metaloproteinase 9 da Matriz/efeitos da radiação , Vimentina/efeitos da radiação
8.
J Appl Clin Med Phys ; 16(5): 193-204, 2015 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-26699300

RESUMO

We have investigated the combined effect of tissue heterogeneity and its variation associated with geometric error in stereotactic body radiotherapy (SBRT) for lung cancer. The treatment plans for eight lung cancer patients were calculated using effective path length (EPL) correction and Monte Carlo (MC) algorithms, with both having the same beam configuration for each patient. These two kinds of plans for individual patients were then subsequently recalculated with adding systematic and random geometric errors. In the ordinary treatment plans calculated with no geometric offset, the EPL calculations, compared with the MC calculations, largely overestimated the doses to PTV by ~ 21%, whereas the overestimation were markedly lower in GTV by ~ 12% due to relatively higher density of GTV than of PTV. When recalculating the plans for individual patients with assigning the systematic and random geometric errors, no significant changes in the relative dose distribution, except for overall shift, were observed in the EPL calculations, whereas largely altered in the MC calculations with a consistent increase in dose to GTV. Considering the better accuracy of MC than EPL algorithms, the present results demonstrated the strong coupling of tissue heterogeneity and geometric error, thereby emphasizing the essential need for simultaneous correction for tissue heterogeneity and geometric targeting error in SBRT of lung cancer.


Assuntos
Tomografia Computadorizada Quadridimensional/métodos , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/cirurgia , Radiocirurgia/métodos , Erros de Configuração em Radioterapia , Cirurgia Assistida por Computador/métodos , Algoritmos , Tomografia Computadorizada Quadridimensional/instrumentação , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Método de Monte Carlo , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Carga Tumoral
9.
J Ocul Pharmacol Ther ; 31(10): 617-22, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26348718

RESUMO

PURPOSE: A prospective study was performed to compare the ocular pulse amplitude (OPA)-lowering effects of tafluprost and latanoprost, used in the treatment of glaucoma, using dynamic contour tonometry. METHODS: The study population consisted of patients with normal-tension glaucoma (NTG) (n = 27) or primary open-angle glaucoma (POAG) (n = 14) treated with tafluprost and latanoprost. All patients were newly diagnosed with NTG and POAG and had undergone no previous treatment. Intraocular pressure (IOP) was measured by Goldmann applanation tonometry (GAT), OPA was measured by dynamic contour tonometry, and corrected OPA (cOPA) was calculated before and after 1 week, 1-3 months of treatment. RESULTS: Initial IOP and OPA were 17.12 ± 3.75, 2.30 ± 0.56 mmHg and 17.53 ± 2.87, 2.65 ± 0.94 mmHg in the tafluprost and latanoprost groups, respectively. After 3 months of treatment, IOP and OPA were 13.00 ± 2.04 mmHg (24.1%) and 1.51 ± 0.30 mmHg (34.3%), respectively, in the tafluprost group. These values were 15.40 ± 2.32 mmHg (12.2%) and 2.08 ± 0.83 mmHg (21.5%), respectively, in the latanoprost group. Therefore, tafluprost significantly reduced IOP (P = 0.01), but OPA-lowering effects did not differ significantly between the 2 groups (P = 0.17). However, the cOPA-lowering effect of tafluprost (1.27 mmHg, 55.2%) was significantly greater than that of latanoprost (0.84 mmHg, 31.7%) after 3 months of treatment (P < 0.001). CONCLUSIONS: Tafluprost and latanoprost, used to treat glaucoma, have marked OPA-lowering effects as well as IOP-lowering effects. Moreover, tafluprost has a greater effect than latanoprost. Therefore, it can be used for patients in need of IOP reduction and at risk of glaucoma progression.


Assuntos
Glaucoma de Ângulo Aberto/tratamento farmacológico , Glaucoma de Baixa Tensão/tratamento farmacológico , Prostaglandinas F Sintéticas/uso terapêutico , Prostaglandinas F/uso terapêutico , Adulto , Idoso , Anti-Hipertensivos/administração & dosagem , Anti-Hipertensivos/uso terapêutico , Feminino , Glaucoma de Ângulo Aberto/patologia , Humanos , Pressão Intraocular/efeitos dos fármacos , Latanoprosta , Glaucoma de Baixa Tensão/patologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Prostaglandinas F/administração & dosagem , Prostaglandinas F Sintéticas/administração & dosagem , Tonometria Ocular , Resultado do Tratamento
10.
Invest Ophthalmol Vis Sci ; 55(12): 7925-33, 2014 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-25406286

RESUMO

PURPOSE: We evaluated the angiographic features of the affected limbus in patients with pterygia and assessed limbal reconstruction outcomes after limbal-conjunctival autograft (LCA) transplantation in terms of vascular remodeling. METHODS: We studied prospectively 31 eyes of 31 patients who underwent pterygium excision and LCA transplantation; 28 eyes of 28 normal participants served as controls. Anterior segment indocyanine green angiography (ICGA) was performed for each participant preoperatively and at 1 week, and 1 and 3 months postoperatively. The perioperative angiographic features of the pterygium were compared to those in normal eyes. The structural changes of the marginal corneal vascular arcades (MCAs) and LCA were quantitatively assessed postoperatively in terms of vascular density and lacunarity. RESULTS: Deteriorated MCAs that extended beyond the pterygium head were observed in the pterygium group. The pterygium had a dual blood supply from the conjunctival and episcleral circulations. In terms of limbal reconstruction, the engorged reperfusion vessels arose from the adjacent episcleral vessels along the limbus at 1 week postoperatively. The reconstructed MCAs had begun to appear at 1 month postoperatively and became apparent 3 months postoperatively in 26 (83.9%) of 31 eyes of the pterygium group, resulting in a successful clinical outcome. Higher vascular density and lower lacunarity were measured in the limbus and the graft at 3 months than at 1 month (P < 0.001 for all), which indicated fine reorganization of the reconstructed vessels. CONCLUSIONS: The pterygium had a dual blood supply, and the remodeling of the affected limbus and LCA continued up to 3 months postoperatively.


Assuntos
Túnica Conjuntiva/transplante , Transplante de Córnea , Limbo da Córnea/irrigação sanguínea , Pterígio/cirurgia , Idoso , Estudos de Casos e Controles , Transplante de Córnea/métodos , Feminino , Angiofluoresceinografia , Humanos , Limbo da Córnea/patologia , Limbo da Córnea/cirurgia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Pterígio/patologia , Transplante Autólogo
11.
Australas Phys Eng Sci Med ; 37(4): 635-44, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25154880

RESUMO

Conventional laser accelerated proton beam has broad energy spectra. It is not suitable for clinical use directly, so it is necessary for employing energy selection system. However, in the conventional laser accelerated proton system, the intensity of the proton beams in the low energy regime is higher than that in the high energy regime. Thus, to generate spread-out-Bragg peak (SOBP), stronger weighting value to the higher energy proton beams is needed and weaker weighting value to the lower energy proton beams is needed, which results in the wide range of weighting values. The purpose of this research is to investigate a method for efficient generating of the SOBP with varying magnetic field in the energy selection system using a carbon-proton mixture target. Energy spectrum of the laser accelerated proton beams was acquired using Particle-In-Cell simulations. The Geant4 Monte Carlo simulation toolkit was implemented for energy selection, particle transportation, and dosimetric property measurement. The energy selection collimator hole size of the energy selection system was changed from 1 to 5 mm in order to investigate the effect of hole size on the dosimetric properties for Bragg peak and SOBP. To generate SOBP, magnetic field in the energy selection system was changed during beam irradiation with each beam weighting factor. In this study, our results suggest that carbon-proton mixture target based laser accelerated proton beams can generate quasi-monoenergetic energy distribution and result in the efficient generation of SOBP. A further research is needed to optimize SOBP according to each range and modulated width using an optimized weighting algorithm.


Assuntos
Carbono/efeitos da radiação , Lasers , Modelos Estatísticos , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Alta Energia/métodos , Algoritmos , Simulação por Computador , Humanos , Método de Monte Carlo , Terapia com Prótons , Dosagem Radioterapêutica
12.
Med Phys ; 40(5): 051716, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23635264

RESUMO

PURPOSE: To examine the dosimetric effect of intrafraction movements occurred during image-guided frameless brain radiosurgery and to derive the optimal margin recipe to compensate the movement. METHODS: The patients' movements during image-guided radiosurgeries were measured using skull-tracking method incorporated in the CyberKnife system. The dosimetric changes with the movements were computed using the six different dynamic-arc treatment plans based on the dose-grid analysis method. The authors extensively searched the proper relationship between the dose variations and the intrafraction geometric errors. The optimal margin for intrafraction movement was estimated via statistical analysis of the dosimetric changes with 262 actual patients' data. RESULTS: The overall geometric effect of intrafraction movements was approximated as 1.0 r+0.2σ, where r and σ are the average and standard deviation of the movements, respectively. The authors computed the required margins to compensate the movements with various confidence levels and with various estimated times for completing the treatments. The computed optimal margins were calculated as 2.1, 3.2, and 4.2 mm at 90% confidence level when the authors assumed the estimated treatment times of 10, 20, and 30 min, respectively. CONCLUSIONS: The authors provide a quantitative relationship for dosimetric change with the intrafraction movement and derived appropriate margin recipes to ensure the prescribed dose delivery to targeted area for frameless brain radiosurgery.


Assuntos
Encéfalo/diagnóstico por imagem , Fracionamento da Dose de Radiação , Movimento , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Radiografia , Radiometria , Fatores de Tempo
13.
J Appl Clin Med Phys ; 14(2): 4055, 2013 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-23470935

RESUMO

We evaluated the dosimetric effect of a respiration motion, and sought an effective planning strategy to compensate the motion using four-dimensional computed tomography (4D CT) dataset of seven selected liver patients. For each patient, we constructed four different proton plans based on: (1) average (AVG) CT, (2) maximum-intensity projection (MIP) CT, (3) AVG CT with density override of tumor volume (OVR), and (4) AVG CT with field-specific proton margin which was determined by the range difference between AVG and MIP plans (mAVG). The overall effectiveness of each planning strategy was evaluated by calculating the cumulative dose distribution over an entire breathing cycle. We observed clear differences between AVG and MIP CT-based plans, with significant underdosages at expiratory and inspiratory phases, respectively. Only the mAVG planning strategy was fully successful as the field-specific proton margin applied in the planning strategy complemented both the limitations of AVG and MIP CT-based strategies. These results demonstrated that respiration motion induced significant changes in dose distribution of 3D proton plans for mobile liver cancer and the changes can be effectively compensated by applying field-specific proton margin to each proton field.


Assuntos
Artefatos , Tomografia Computadorizada Quadridimensional/métodos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Mecânica Respiratória , Humanos , Movimento (Física) , Terapia com Prótons , Dosagem Radioterapêutica , Radioterapia Guiada por Imagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
14.
Radiat Oncol J ; 31(4): 234-8, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24501712

RESUMO

PURPOSE: Esophageal tolerance is needed to guide the safe administration of stereotactic radiosurgery (SRS). We evaluated comprehensive dose-volume parameters of acute esophageal toxicity in patients with spinal metastasis treated with SRS. MATERIALS AND METHODS: From May 2008 to May 2011, 30 cases in 27 patients with spinal metastasis received single fraction SRS to targets neighboring esophagus. Endpoints evaluated include length (mm), volume (mL), maximal dose (Gy), and series of dose-volume thresholds from the dose-volume histogram (volume of the organ treated beyond a threshold dose). RESULTS: The median time from the start of irradiation to development of esophageal toxicity was 2 weeks (range, 1 to 12 weeks). Six events of grade 1 esophageal toxicity occurred. No grade 2 or higher events were observed. V15 of external surface of esophagus was found to predict acute esophageal toxicity revealed by multivariate analysis (odds radio = 1.272, p = 0.047). CONCLUSION: In patients with spinal metastasis who received SRS for palliation of symptoms, the threshold dose-volume parameter associated with acute esophageal toxicity was found to be V15 of external surface of esophagus. Restrict V15 to external surface of esophagus as low as possible might be safe and feasible in radiosurgery.

15.
Korean Circ J ; 42(8): 562-4, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22977453

RESUMO

A young male patient diagnosed with Klinefelter syndrome was admitted to our hospital via the emergency room with chief complaints of acute chest pain and dyspnea. Pulmonary thromboembolism was diagnosed from his chest CT images. His symptoms improved after he underwent thrombolysis and anticoagulation treatment. Klinefelter syndrome has a tendency towards hypercoagulability due to hormonal imbalance and one or more inherited thromophilic factors. Thus, Klinefelter syndrome patients with a past medical history of venous thromboembolism require continuous oral anticoagulation therapy for a period of at least six months.

16.
J Korean Med Sci ; 27(9): 1044-50, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22969250

RESUMO

IMR is useful for assessing the microvascular dysfunction after primary percutaneous coronary intervention (PCI). It remains unknown whether index of microcirculatory resistance (IMR) reflects the functional outcome in patients with anterior myocardial infarction (AMI) with or without microvascular obstruction (MO).This study was performed to evaluate the clinical value of the IMR for assessing myocardial injury and predicting microvascular functional recovery in patients with AMI undergoing primary PCI. We enrolled 34 patients with first anterior AMI. After successful primary PCI, the mean distal coronary artery pressure (P(a)), coronary wedge pressure (P(cw)), mean aortic pressure (P(a)), mean transit time (T(mn)), and IMR (P(d)* hyperemic T(mn)) were measured. The presence and extent of MO were measured using cardiac magnetic resonance image (MRI). All patients underwent follow-up echocardiography after 6 months. We divided the patients into two groups according to the existence of MO (present; n = 16, absent; n = 18) on MRI. The extent of MO correlated with IMR (r = 0.754; P < 0.001), P(cw) (r = 0.404; P = 0.031), and P(cw)/P(d) of infarct-related arteries (r = 0.502; P = 0.016). The IMR was significantly correlated with the ΔRegional wall motion score index (r = -0.61, P < 0.01) and ΔLeft ventricular ejection fraction (r = -0.52, P < 0.01), implying a higher IMR is associated with worse functional improvement. Therefore, Intracoronary wedge pressures and IMR, as parameters for specific and quantitative assessment of coronary microvascular dysfunction, are reliable on-site predictors of short-term myocardial viability and Left ventricle functional recovery in patients undergoing primary PCI for AMI.


Assuntos
Infarto Miocárdico de Parede Anterior/fisiopatologia , Microcirculação/fisiologia , Valor Preditivo dos Testes , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão Arterial/fisiologia , Oclusão Coronária/patologia , Ecocardiografia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea , Estudos Prospectivos , Recuperação de Função Fisiológica , Fatores de Risco
17.
Med Phys ; 39(7): 4265-73, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22830760

RESUMO

PURPOSE: A new motion-based gated proton therapy for the treatment of orbital tumors using real-time eye-tracking system was designed and evaluated. METHODS: We developed our system by image-pattern matching, using a normalized cross-correlation technique with LabVIEW 8.6 and Vision Assistant 8.6 (National Instruments, Austin, TX). To measure the pixel spacing of an image consistently, four different calibration modes such as the point-detection, the edge-detection, the line-measurement, and the manual measurement mode were suggested and used. After these methods were applied to proton therapy, gating was performed, and radiation dose distributions were evaluated. RESULTS: Moving phantom verification measurements resulted in errors of less than 0.1 mm for given ranges of translation. Dosimetric evaluation of the beam-gating system versus nongated treatment delivery with a moving phantom shows that while there was only 0.83 mm growth in lateral penumbra for gated radiotherapy, there was 4.95 mm growth in lateral penumbra in case of nongated exposure. The analysis from clinical results suggests that the average of eye movements depends distinctively on each patient by showing 0.44 mm, 0.45 mm, and 0.86 mm for three patients, respectively. CONCLUSIONS: The developed automatic eye-tracking based beam-gating system enabled us to perform high-precision proton radiotherapy of orbital tumors.


Assuntos
Artefatos , Movimentos Oculares , Neoplasias Oculares/patologia , Neoplasias Oculares/radioterapia , Aumento da Imagem/métodos , Reconhecimento Automatizado de Padrão/métodos , Radioterapia Guiada por Imagem/métodos , Algoritmos , Humanos , Movimento (Física) , Terapia com Prótons , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
18.
J Radiol Prot ; 31(4): 477-87, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22089084

RESUMO

We have estimated the secondary cancer risk (SCR) introduced by image-guided procedures during proton therapy. The physical dose from imaging radiation and the corresponding organ equivalent dose were calculated for the case of a lumbar spine patient. The maximum physical dose delivered to the patient during the imaging procedure was estimated to be ~0.35% of the prescribed dose of 46 Gy. However, this small imaging dose substantially raised the radiation-induced SCR by ~8%. In addition, the clinical benefit (improved accuracy during the procedure) and costs (extra SCR) associated with image-guided procedures were quantitatively modelled by systematically investigating the changes in SCR as a function of the prescribed dose, treatment target volume and imaging field size. The results showed that the SCR varied sensitively with the volume receiving the imaging and the therapeutic radiation, whereas the SCR depended to a lesser extent on the magnitude of the applied therapeutic radiation. These results showed that the additional SCR introduced by imaging radiation could be efficiently reduced by minimizing the imaging field size during image-guided procedures.


Assuntos
Diagnóstico por Imagem/efeitos adversos , Modelos Biológicos , Neoplasias Induzidas por Radiação/etiologia , Radioterapia Conformacional/efeitos adversos , Radioterapia Guiada por Imagem/efeitos adversos , Simulação por Computador , Feminino , Humanos , Terapia com Prótons , Prótons/efeitos adversos , Medição de Risco
19.
Yonsei Med J ; 52(6): 939-47, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22028157

RESUMO

PURPOSE: The aim of this study was to identify the most precise and clinically practicable parameters that predict future oral hypoglycemic agent (OHA) failure in patients with type 2 diabetes, and to determine whether these parameters are valuable in various subgroups. MATERIALS AND METHODS: We took fasting blood samples from 231 patients for laboratory data and standard breakfast tests for evaluation of pancreatic beta-cell function. Hemoglobin A1c (HbA1c) levels were tested, and we collected data related to hypoglycemic medications one year from the start date of the study. RESULTS: Fasting C-peptide, postprandial insulin and C-peptide, the difference between fasting and postprandial insulin, fasting beta-cell responsiveness (M0), postprandial beta-cell responsiveness (M1), and homeostasis model assessment-beta (HOMA-B) levels were significantly higher in those with OHA response than in those with OHA failure. The area under the curve (AUC) of the receiver operating characteristic (ROC) measured with postprandial C-peptide to predict future OHA failure was 0.720, and the predictive power for future OHA failure was the highest of the variable parameters. Fasting and postprandial C-peptide, M0, and M1 levels were the only differences between those with OHA response and those with OHA failure among diabetic subjects with low body mass index, high blood glucose level, or long-standing diabetes. CONCLUSION: In conclusion, postprandial C-peptide was most useful in predicting future OHA failure in type 2 diabetic subjects. However, these parameters measuring beta-cell function are only valuable in diabetic subjects with low body mass index, high blood glucose level, or long-standing diabetes.


Assuntos
Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/fisiologia , Administração Oral , Adolescente , Idoso , Glicemia/análise , Índice de Massa Corporal , Peptídeo C/sangue , Criança , Pré-Escolar , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/fisiopatologia , Jejum/sangue , Feminino , Humanos , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/uso terapêutico , Insulina/sangue , Masculino , Pessoa de Meia-Idade , Período Pós-Prandial
20.
Environ Manage ; 44(2): 278-87, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19548022

RESUMO

This study attempts to apply choice experiments with regard to the residential waste disposal system (RWDS) in Korea by considering various attributes that are related to RWDS. Using data from a survey conducted on 492 households, the empirical analysis yields estimates of the willingness to pay for a clean food-waste collection facility, the collection of small items (such as obsolete mobile phones and add-ons for personal computers), and a more convenient large waste disposal system. The estimation results of multinomial logit models are quite similar to those of nested logit models. The results reveal that residents have preferences for the cleanliness of facilities and the collection of small items. In Korea, residents are required to purchase and attach stickers for the disposal of large items; they want to be able to obtain stickers at not only village offices but also supermarkets. On the other hand, the frequency of waste collection is not a significant factor in the choice of the improved waste management program.


Assuntos
Eliminação de Resíduos/economia , Gerenciamento de Resíduos/economia , Gerenciamento de Resíduos/métodos , Custos e Análise de Custo , Coreia (Geográfico) , Modelos Teóricos , Opinião Pública , Eliminação de Resíduos/métodos
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