960 resultados para Radiation use efficiency


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Recombinant human tumour necrosis factor (TNF) has a selective effect on angiogenic vessels in tumours. Given that it induces vasoplegia, its clinical use has been limited to administration through isolated limb perfusion (ILP) for regionally advanced melanomas and soft tissue sarcomas of the limbs. When combined with the alkylating agent melphalan, a single ILP produces a very high objective response rate. In melanoma, the complete response (CR) rate is around 80% and the overall objective response rate greater than 90%. In soft tissue sarcomas that are inextirpable, ILP is a neoadjuvant treatment resulting in limb salvage in 80% of the cases. The CR rate averages 20% and the objective response rate is around 80%. The mode of action of TNF-based ILP involves two distinct and successive effects on the tumour-associated vasculature: first, an increase in endothelium permeability leading to improved chemotherapy penetration within the tumour tissue, and second, a selective killing of angiogenic endothelial cells resulting in tumour vessel destruction. The mechanism whereby these events occur involves rapid (of the order of minutes) perturbation of cell-cell adhesive junctions and inhibition of alphavbeta3 integrin signalling in tumour-associated vessels, followed by massive death of endothelial cells and tumour vascular collapse 24 hours later. New, promising approaches for the systemic use of TNF in cancer therapy include TNF targeting by means of single chain antibodies or endothelial cell ligands, or combined administration with drugs perturbing integrin-dependent signalling and sensitizing angiogenic endothelial cells to TNF-induced death.

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Four standard radiation qualities (from RQA 3 to RQA 9) were used to compare the imaging performance of a computed radiography (CR) system (general purpose and high resolution phosphor plates of a Kodak CR 9000 system), a selenium-based direct flat panel detector (Kodak Direct View DR 9000), and a conventional screen-film system (Kodak T-MAT L/RA film with a 3M Trimax Regular screen of speed 400) in conventional radiography. Reference exposure levels were chosen according to the manufacturer's recommendations to be representative of clinical practice (exposure index of 1700 for digital systems and a film optical density of 1.4). With the exception of the RQA 3 beam quality, the exposure levels needed to produce a mean digital signal of 1700 were higher than those needed to obtain a mean film optical density of 1.4. In spite of intense developments in the field of digital detectors, screen-film systems are still very efficient detectors for most of the beam qualities used in radiology. An important outcome of this study is the behavior of the detective quantum efficiency of the digital radiography (DR) system as a function of beam energy. The practice of users to increase beam energy when switching from a screen-film system to a CR system, in order to improve the compromise between patient dose and image quality, might not be appropriate when switching from screen-film to selenium-based DR systems.

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Background: Interventional catheterization is being increasingly used for relief of residual lesions in congenital heart disease. Exact anatomical imaging is crucial in the planning of an intervention. This can be provided non-invasively and without radiation by contrast-enhanced MR angiography (CEMRA). Aim: To evaluate the accuracy of the measurements of the vessels obtained by CEMRA in comparison to those obtained by conventional X-ray angiography (CXA). Methods: Retrospective blinded measurement of the diameters of aorta and pulmonary arteries on the CEMRA and CXA images, in the same locations. Comparison of the results by Pearson correlation and by calculating the limits of agreement. Results: Twenty-one children with congenital heart disease, mean age 5.6 +- 5.2 years, weight 21.1 +- 18.4 kg, underwent CEMRA and catheterization for assessment or treatment of a residual lesion. The time interval between the CEMRA and the CXA examination was 2.6 +- 2.3 months. A total of 98 measurements, 37 of the aorta and 61 of the pulmonary arteries were performed on the images obtained by each technique. The correlation between CEMRA and CXA measurements was excellent, r = 0.97, p < 0.0001. The mean difference between the two techniques was 0.018 +- 1.1mm; the limits of agreement were -2.14 and +2.18mm. Similar agreement was found for measures of the aorta (r +- 0.97, mean difference 0.20 = 1.08 mm) and of the pulmonary arteries (r +- 0.97, mean difference 0.048 = 0.89 mm). Conclusions: CEMRA provide accurate quantitative anatomical information, which highly agrees with CXA data, and can therefore be used for planning interventional catheterization.

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Many workers believe that personal contacts are crucial for obtainingjobs in high-wage sectors. On the other hand, firms in high-wage sectorsreport using employee referrals because they help provide screening andmonitoring of new employees. This paper develops a matching model thatcan explain the link between inter-industry wage differentials and useof employee referrals. Referrals lower monitoring costs because high-effortreferees can exert peer pressure on co-workers, allowing firms to pay lowerefficiency wages. On the other hand, informal search provides fewer job andapplicant contacts than formal methods (e.g., newspaper ads). In equilibrium,the matching process generates segmentation in the labor market becauseof heterogeneity in the size of referral networks. Referrals match good high-paying jobs to well-connected workers, while formal methods matchless attractive jobs to less-connected workers. Industry-level data show apositive correlation between industry wage premia and use of employeereferrals. Moreover, evidence using the NLSY shows similar positive andsignificant OLS and fixed-effects estimates of the returns to employeereferrals, but insignificant effects once sector of employment is controlledfor. This evidence suggests referred workers earn higher wages not becauseof higher unobserved ability or better matches but rather because theyare hired in high-wage sectors.

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PURPOSE: The Gastro-Intestinal Working Party of the EORTC Radiation Oncology Group (GIWP-ROG) developed guidelines for target volume definition in neoadjuvant radiation of adenocarcinomas of the gastroesophageal junction (GEJ) and the stomach. METHODS AND MATERIALS: Guidelines about the definition of the clinical target volume (CTV) are based on a systematic literature review of the location and frequency of local recurrences and lymph node involvement in adenocarcinomas of the GEJ and the stomach. Therefore, MEDLINE was searched up to August 2008. Guidelines concerning prescription, planning and treatment delivery are based on a consensus between the members of the GIWP-ROG. RESULTS: In order to support a curative resection of GEJ and gastric cancer, an individualized preoperative treatment volume based on tumour location has to include the primary tumour and the draining regional lymph nodes area. Therefore we recommend to use the 2nd English Edition of the Japanese Classification of Gastric Carcinoma of the Japanese Gastric Cancer Association which developed the concept of assigning tumours of the GEJ and the stomach to anatomically defined sub-sites corresponding respectively to a distinct lymphatic spread pattern. CONCLUSION: The GIWP-ROG defined guidelines for preoperative irradiation of adenocarcinomas of the GEJ and the stomach to reduce variability in the framework of future clinical trials.

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The emphasis on integrated care implies new incentives that promote coordinationbetween levels of care. Considering a population as a whole, the resource allocation systemhas to adapt to this environment. This research is aimed to design a model that allows formorbidity related prospective and concurrent capitation payment. The model can be applied inpublicly funded health systems and managed competition settings.Methods: We analyze the application of hybrid risk adjustment versus either prospective orconcurrent risk adjustment formulae in the context of funding total health expenditures for thepopulation of an integrated healthcare delivery organization in Catalonia during years 2004 and2005.Results: The hybrid model reimburses integrated care organizations avoiding excessive risktransfer and maximizing incentives for efficiency in the provision. At the same time, it eliminatesincentives for risk selection for a specific set of high risk individuals through the use ofconcurrent reimbursement in order to assure a proper classification of patients.Conclusion: Prospective Risk Adjustment is used to transfer the financial risk to the healthprovider and therefore provide incentives for efficiency. Within the context of a National HealthSystem, such transfer of financial risk is illusory, and the government has to cover the deficits.Hybrid risk adjustment is useful to provide the right combination of incentive for efficiency andappropriate level of risk transfer for integrated care organizations.

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In Switzerland, the issue of land consumption has made it to the front of the political agenda in recent years. Studies conducted on a national level have concluded that there is an excess of land zoned for construction (ARE, 2008), which is seen as contributing to urban sprawl. This situation is looked upon as a failure of the Federal Law on Spatial Planning (LAT, 1979) and there is a political push to change it in order to reinforce zoning regulations. In this article, we look on the issue from a different angle. While there may be large quantities of land zoned for construction, in many urban areas land actually available for development is scarce. Building on the idea that planning's efficiency is linked to its capacity of influencing actual land-use, we focus on how this situation can be dealt with within the current Swiss institutional context.

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The research performed a sustainability assessment of supply chains of the anchoveta (Engraulis ringens) in Peru. The corresponding fisheries lands 6.5 million t per year, of which <2% is rendered into products for direct human consumption (DHC) and 98% reduced into feed ingredients (fishmeal and fish oil, FMFO), for export. Several industries compete for the anchoveta resources, generating local and global impacts. The need for understanding these dynamics, towards sustainability-improving management and policy recommendations, determined the development of a sustainability assessment framework: 1) characterisation and modelling of the systems under study (with Life Cycle Assessment and other tools) including local aquaculture, 2) calculation of sustainability indicators (i.e. energy efficiency, nutritional value, socio-economic performances), and 3) sustainability comparison of supply chains; definition and comparison of alternative exploitation scenarios. Future exploitation scenarios were defined by combining an ecosystem and a material flow models: continuation of the status quo (Scenario 1), shift towards increased proportion of DHC production (Scenario 2), and radical reduction of the anchoveta harvest in order for other fish stocks to recover and be exploited for DHC (Scenario 3). Scenario 2 was identified as the most sustainable. Management and policy recommendations include improving of: controls for compliance with management measures, sanitary conditions for DHC, landing infrastructure for small- and medium-scale (SMS) fisheries; the development of a national refrigerated distribution chain; and the assignation of flexible tolerances for discards from different DHC processes.

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The interest in solar ultraviolet (UV) radiation from the scientific community and the general population has risen significantly in recent years because of the link between increased UV levels at the Earth's surface and depletion of ozone in the stratosphere. As a consequence of recent research, UV radiation climatologies have been developed, and effects of some atmospheric constituents (such as ozone or aerosols) have been studied broadly. Correspondingly, there are well-established relationships between, for example, total ozone column and UV radiation levels at the Earth's surface. Effects of clouds, however, are not so well described, given the intrinsic difficulties in properly describing cloud characteristics. Nevertheless, the effect of clouds cannot be neglected, and the variability that clouds induce on UV radiation is particularly significant when short timescales are involved. In this review we show, summarize, and compare several works that deal with the effect of clouds on UV radiation. Specifically, works reviewed here approach the issue from the empirical point of view: Some relationship between measured UV radiation in cloudy conditions and cloud-related information is given in each work. Basically, there are two groups of methods: techniques that are based on observations of cloudiness (either from human observers or by using devices such as sky cameras) and techniques that use measurements of broadband solar radiation as a surrogate for cloud observations. Some techniques combine both types of information. Comparison of results from different works is addressed through using the cloud modification factor (CMF) defined as the ratio between measured UV radiation in a cloudy sky and calculated radiation for a cloudless sky. Typical CMF values for overcast skies range from 0.3 to 0.7, depending both on cloud type and characteristics. Despite this large dispersion of values corresponding to the same cloud cover, it is clear that the cloud effect on UV radiation is 15–45% lower than the cloud effect on total solar radiation. The cloud effect is usually a reducing effect, but a significant number of works report an enhancement effect (that is increased UV radiation levels at the surface) due to the presence of clouds. The review concludes with some recommendations for future studies aimed to further analyze the cloud effects on UV radiation

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OBJECT: The aim of this study was to evaluate the long-term safety and efficacy of bilateral contemporaneous deep brain stimulation (DBS) in patients who have levodopa-responsive parkinsonism with untreatable motor fluctuations. Bilateral pallidotomy carries a high risk of corticobulbar and cognitive dysfunction. Deep brain stimulation offers new alternatives with major advantages such as reversibility of effects, minimal permanent lesions, and adaptability to individual needs, changes in medication, side effects, and evolution of the disease. METHODS: Patients in whom levodopa-responsive parkinsonism with untreatable severe motor fluctuations has been clinically diagnosed underwent bilateral pallidal magnetic resonance image-guided electrode implantation while receiving a local anesthetic. Pre- and postoperative evaluations at 3-month intervals included Unified Parkinson's Disease Rating Scale (UPDRS) scoring, Hoehn and Yahr staging, 24-hour self-assessments, and neuropsychological examinations. Six patients with a mean age of 55 years (mean 42-67 years), a mean duration of disease of 15.5 years (range 12-21 years), a mean "on/off' Hoehn and Yahr stage score of 3/4.2 (range 3-5), and a mean "off' time of 40% (range 20-50%) underwent bilateral contemporaneous pallidal DBS, with a minimum follow-up period lasting 24 months (range 24-30 months). The mean dose of levodopa in these patients could not be changed significantly after the procedure and pergolide was added after 12 months in five patients because of recurring fluctuations despite adjustments in stimulation parameters. All but two patients had no fluctuations until 9 months. Two of the patients reported barely perceptible fluctuations at 12 months and two at 15 months; however, two patients remain without fluctuations at 2 years. The mean improvements in the UPDRS motor score in the off time and the activities of daily living (ADL) score were more than 50%; the mean off time decreased from 40 to 10%, and the mean dyskinesia and complication of treatment scores were reduced to one-third until pergolide was introduced at 12 months. No significant improvement in "on" scores was observed. A slight worsening after 1 year was observed and three patients developed levodopa- and stimulation-resistant gait ignition failure and minimal fluctuations at 1 year. Side effects, which were controlled by modulation of stimulation, included dysarthria, dystonia, and confusion. CONCLUSIONS: Bilateral pallidal DBS is safe and efficient in patients who have levodopa-responsive parkinsonism with severe fluctuations. Major improvements in motor score, ADL score, and off time persisted beyond 2 years after the operation, but signs of decreased efficacy started to be seen after 12 months.

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Public Works is pleased to present the following Iowa Efficiency Review Report to Governor Chet Culver and Lieutenant Governor Patty Judge. This report is the product of a collaboration between our consulting team and very dedicated Iowa state employees who worked with us to share ideas and cost‐saving proposals under very difficult circumstances caused by the national financial crisis that is affecting state budgets throughout the country. For example, during the course of this review, Iowa departments were also asked to develop across‐the‐board cuts to achieve immediate reductions in state spending. It is a credit to Iowa state government that departmental staff continued to work on this Efficiency Review Report despite these challenges of also having to develop across‐the‐board budget cuts to achieve a balanced budget. We hope that these ideas will set the stage for further future budget improvements from achieving efficiencies, eliminating outdated practices, increasing the use of information technology solutions and finding new sources of non‐tax funding. The Efficiency Review Team faced a second challenge. Statewide Efficiency Reviews usually take from nine to 12 months to complete. In Iowa, we worked with dedicated department staff to complete our work in less than 4 months. The Governor challenged all of us to work intensely and to give him our best thinking on efficiency proposals so that he could act as quickly as possible to position state government for success over the next several years.

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L'hormonoradiothérapie concomitante est utilisée depuis plusieurs années en pratique clinique quotidienne dans les cancers localement évolués de la prostate. Le transfert de ce concept en pathologie mammaire a été très peu rapporté dans la littérature, mais semble pourtant licite devant l'hormonodépendance fréquente des cancers du sein et la synergie potentielle de ces deux armes thérapeutiques. En situation adjuvante, deux stratégies sont actuellement utilisées : la prescription d'un inhibiteur de l'aromatase d'emblée ou après un délai plus ou moins long de tamoxifène. En pratique, ces molécules peuvent donc interagir avec la radiothérapie adjuvante. Les études rétrospectives récemment publiées n'ont pas mis en évidence de différence significative sur l'incidence des évènements, notamment locorégionaux, de l'association concomitante ou séquentielle du tamoxifène à la radiothérapie. La toxicité de l'association reste discutable en termes de fibroses sous-cutanée et pulmonaire. Il semble que le tamoxifène aggraverait les séquelles postradiques uniquement chez les patientes prédisposées à souffrir d'effets tardifs de la radiothérapie et identifiées par un test prédictif biologique. La prudence reste donc encore de mise du moins pour ces patientes. Cet article détaille les avantages et les risques de l'utilisation concomitante de la radiothérapie et de l'hormonothérapie adjuvantes des cancers localisés du sein. Combined radiation and hormone therapies have become common clinical practice in recent years for locally-advanced prostate cancers. The use of such concomitant therapy in the treatment of breast disease has been infrequently reported in the literature, but seems justified given the common hormonal dependence of breast cancer and the potential synergistic effect of these two treatment modalities. As adjuvant therapy, two strategies are used in daily clinical practice: upfront aromatase inhibitors or sequentially after a variable delay of tamoxifen. These molecules may, thus, interact with radiotherapy. Retrospectives studies recently published did not show any differences in terms of locoregional recurrences between concurrent or sequential radiohormonotherapy. Lung and skin fibroses due to concurrent treatment are still under debate. Nevertheless, late side effects appeared to be increased by such a treatment, particularly in hypersensitive patients identified at risk by the lymphocyte predictive test. Concurrent radiohormonotherapy should, thus, be delivered cautiously at least for these patients. This article details the potent advantages and risks of concurrent use of adjuvant hormonotherapy and radiotherapy in localized breast cancers.

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Phase sensitive X-ray imaging methods can provide substantially increased contrast over conventional absorption-based imaging and therefore new and otherwise inaccessible information. The use of gratings as optical elements in hard X-ray phase imaging overcomes some of the problems that have impaired the wider use of phase contrast in X-ray radiography and tomography. So far, to separate the phase information from other contributions detected with a grating interferometer, a phase-stepping approach has been considered, which implies the acquisition of multiple radiographic projections. Here we present an innovative, highly sensitive X-ray tomographic phase-contrast imaging approach based on grating interferometry, which extracts the phase-contrast signal without the need of phase stepping. Compared to the existing phase-stepping approach, the main advantages of this new method dubbed "reverse projection" are not only the significantly reduced delivered dose, without the degradation of the image quality, but also the much higher efficiency. The new technique sets the prerequisites for future fast and low-dose phase-contrast imaging methods, fundamental for imaging biological specimens and in vivo studies.