954 resultados para Procurement of organs, tissues, etc.


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Reports for <1997- > also called <34d- >.

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Allegations of body parts trafficking implicating the West have been surfacing persistently in the media of many non Western countries for almost 20 years. Western media has responded to the allegations with denials and denunciations. This thesis considers the competing accounts and places them in a framework for analysis.

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This theory-building research suggests that the key to unlocking Australia's potential organ donor pool is to reduce the ethical ambiguity and legal uncertainty plaguing physicians' interepretation of the patients's best interests standard. This may generate a greater acceptance of organ donation as part of end-of-life patient care amongst our physicians.

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Includes indexes.

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Pós-graduação em Bases Gerais da Cirurgia - FMB

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"September 1993."--P. [5].

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"October 1985."

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Prior work of our research group, that quantified the alarming levels of radiation dose to patients with Crohn’s disease from medical imaging and the notable shift towards CT imaging making these patients an at risk group, provided context for this work. CT delivers some of the highest doses of ionising radiation in diagnostic radiology. Once a medical imaging examination is deemed justified, there is an onus on the imaging team to endeavour to produce diagnostic quality CT images at the lowest possible radiation dose to that patient. The fundamental limitation with conventional CT raw data reconstruction was the inherent coupling of administered radiation dose with observed image noise – the lower the radiation dose, the noisier the image. The renaissance, rediscovery and refinement of iterative reconstruction removes this limitation allowing either an improvement in image quality without increasing radiation dose or maintenance of image quality at a lower radiation dose compared with traditional image reconstruction. This thesis is fundamentally an exercise in optimisation in clinical CT practice with the objectives of assessment of iterative reconstruction as a method for improvement of image quality in CT, exploration of the associated potential for radiation dose reduction, and development of a new split dose CT protocol with the aim of achieving and validating diagnostic quality submillisiever t CT imaging in patients with Crohn’s disease. In this study, we investigated the interplay of user-selected parameters on radiation dose and image quality in phantoms and cadavers, comparing traditional filtered back projection (FBP) with iterative reconstruction algorithms. This resulted in the development of an optimised, refined and appropriate split dose protocol for CT of the abdomen and pelvis in clinical patients with Crohn’s disease allowing contemporaneous acquisition of both modified and conventional dose CT studies. This novel algorithm was then applied to 50 patients with a suspected acute complication of known Crohn’s disease and the raw data reconstructed with FBP, adaptive statistical iterative reconstruction (ASiR) and model based iterative reconstruction (MBIR). Conventional dose CT images with FBP reconstruction were used as the reference standard with which the modified dose CT images were compared in terms of radiation dose, diagnostic findings and image quality indices. As there are multiple possible user-selected strengths of ASiR available, these were compared in terms of image quality to determine the optimal strength for this modified dose CT protocol. Modified dose CT images with MBIR were also compared with contemporaneous abdominal radiograph, where performed, in terms of diagnostic yield and radiation dose. Finally, attenuation measurements in organs, tissues, etc. with each reconstruction algorithm were compared to assess for preservation of tissue characterisation capabilities. In the phantom and cadaveric models, both forms of iterative reconstruction examined (ASiR and MBIR) were superior to FBP across a wide variety of imaging protocols, with MBIR superior to ASiR in all areas other than reconstruction speed. We established that ASiR appears to work to a target percentage noise reduction whilst MBIR works to a target residual level of absolute noise in the image. Modified dose CT images reconstructed with both ASiR and MBIR were non-inferior to conventional dose CT with FBP in terms of diagnostic findings, despite reduced subjective and objective indices of image quality. Mean dose reductions of 72.9-73.5% were achieved with the modified dose protocol with a mean effective dose of 1.26mSv. MBIR was again demonstrated superior to ASiR in terms of image quality. The overall optimal ASiR strength for the modified dose protocol used in this work is ASiR 80%, as this provides the most favourable balance of peak subjective image quality indices with less objective image noise than the corresponding conventional dose CT images reconstructed with FBP. Despite guidelines to the contrary, abdominal radiographs are still often used in the initial imaging of patients with a suspected complication of Crohn’s disease. We confirmed the superiority of modified dose CT with MBIR over abdominal radiographs at comparable doses in detection of Crohn’s disease and non-Crohn’s disease related findings. Finally, we demonstrated (in phantoms, cadavers and in vivo) that attenuation values do not change significantly across reconstruction algorithms meaning preserved tissue characterisation capabilities with iterative reconstruction. Both adaptive statistical and model based iterative reconstruction algorithms represent feasible methods of facilitating acquisition diagnostic quality CT images of the abdomen and pelvis in patients with Crohn’s disease at markedly reduced radiation doses. Our modified dose CT protocol allows dose savings of up to 73.5% compared with conventional dose CT, meaning submillisievert imaging is possible in many of these patients.

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In the last decade, health authorities in China have made a series of policy announcements concerning organ procurement programs and changes in practice have been intermittently reported (1). The international community of transplant professionals has followed these reports closely, preoccupied with one fundamental issue: the procurement of organs from executed prisoners, a practice that for many years has provided the majority of organs transplanted in China. Sharif et al. describe this practice as “ethically indefensible” (2), an evaluation that reflects the position embraced by the international community for more than two decades (3-5). Sharif et al. express concern that whilst some transplant programs in China have ceased using organs from executed prisoners, others continue to do so, and that all organs procured from the deceased may be allocated through a collective pool as part of the new China Organ Transplant Response System, effectively “laundering” organs obtained from prisoners. They also note that one of the new strategies to encourage deceased donation of organs among the Chinese public has involved financial incentives for donor families, another practice that has been strongly critiqued by the international professional community and global health authorities (6,7).

In China and in the United States, proponents of organ procurement from executed prisoners have argued that prisoners should not be denied the option to donate organs after their death if they so choose, as this may provide them or their families solace and an opportunity for moral, spiritual or social redemption (8,9). However, the predominant argument in favour of the practice appears to be essentially pragmatic: prisoners condemned to death represent an additional pool of potential “donors” with organs that will otherwise “go to waste” (10). In contrast, international professional societies and the World Health Organization among others have argued that the practice not only violates the core principles of medical ethics but also thereby undermines efforts to establish a sufficient supply of deceased donor organs. In this commentary, we reaffirm the ethics policy of The Transplantation Society (TTS) concerning organ procurement from executed prisoners (4), and briefly discuss the implications of this policy for international professional engagement with China at this time of significant evolution of Chinese organ procurement programs.