21 resultados para open quantum system


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PURPOSE OF THE STUDY: Fracture of the tibial pilon is a rare injury and its treatment remains difficult. The aim of this study was to report the complications and long term results of internal fixation using a technique which respects soft tissues and in which little material was used. MATERIAL: From 1985 to 1990, 48 patients with 51 fractures of the tibial pilon were treated by open reduction and internal fixation. All patients were submitted to a clinical and radiological review. METHODS: Both the Rüedi/Allgöwer and the AO-classification were used and determined by standard X-rays. Surgical procedure was performed with a 2 or 3 1/3 tube AO-plates and the peroneus was always fixed if fractured. Intraoperative reconstruction was analyzed. Subjective and objective scoring were used according to Olerud and Molander and the ankle arthritis was scored according to the classification determined by the SOFCOT in 1992. RESULTS: A minimal follow-up of 1 year for all cases was obtained, based on our own files. Thirty-eight patients (40 fractures) were evaluated after an average period of 88 months (56 to 124 months). Five patients developed cutaneous infection, three developed deep infection and four developed superficial skin necrosis. One aseptic non-union necessitated reoperation after 14 months. Two ankles had joint fusion after 19 and 25 months respectively due to severe arthritis. In six cases infectious and non-infectious complications led to surgical revision. According to the Olerud and Molander score, 15 per cent of the results were excellent, 45 per cent were good, 30 per cent were fair and 10 per cent poor. DISCUSSION: Literature shows a wide range of results following this surgical procedure. This is due to the difference in the type of trauma, classification system used, material used for the internal fixation and method of evaluation. The classification system of Rüedi and Allgöwer is the most commonly used but has a rather subjective tendency, especially between type II and type III. Treatment is difficult, especially for comminutive fractures associated with soft tissue damage. In this case, open reduction and internal fixation could increase iatrogenic lesions. For this reason surgical procedure can be delayed for several days, little material is used and soft tissue manipulation is reduced to minimum. In other study reports, the use of external fixation with or without minimal internal fixation have produced less complications without improving long term results. CONCLUSION: Analysis and comparison of study reports are difficult because of the absence of consensus in classification system and evaluation methods. The AO-classification, apparently the most objective, will probably be more and more used in the future. Treatment must be adapted to the bony lesion and soft tissue damage. Open reduction and internal fixation must be reserved for a specific group of lesion.

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Three standard radiation qualities (RQA 3, RQA 5 and RQA 9) and two screens, Kodak Lanex Regular and Insight Skeletal, were used to compare the imaging performance and dose requirements of the new Kodak Hyper Speed G and the current Kodak T-MAT G/RA medical x-ray films. The noise equivalent quanta (NEQ) and detective quantum efficiencies (DQE) of the four screen-film combinations were measured at three gross optical densities and compared with the characteristics for the Kodak CR 9000 system with GP (general purpose) and HR (high resolution) phosphor plates. The new Hyper Speed G film has double the intrinsic sensitivity of the T-MAT G/RA film and a higher contrast in the high optical density range for comparable exposure latitude. By providing both high sensitivity and high spatial resolution, the new film significantly improves the compromise between dose and image quality. As expected, the new film has a higher noise level and a lower signal-to-noise ratio than the standard film, although in the high frequency range this is compensated for by a better resolution, giving better DQE results--especially at high optical density. Both screen-film systems outperform the phosphor plates in terms of MTF and DQE for standard imaging conditions (Regular screen at RQA 5 and RQA 9 beam qualities). At low energy (RQA 3), the CR system has a comparable low-frequency DQE to screen-film systems when used with a fine screen at low and middle optical densities, and a superior low-frequency DQE at high optical density.

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PURPOSE: EOS (EOS imaging S.A, Paris, France) is an x-ray imaging system that uses slot-scanning technology in order to optimize the trade-off between image quality and dose. The goal of this study was to characterize the EOS system in terms of occupational exposure, organ doses to patients as well as image quality for full spine examinations. METHODS: Occupational exposure was determined by measuring the ambient dose equivalents in the radiological room during a standard full spine examination. The patient dosimetry was performed using anthropomorphic phantoms representing an adolescent and a five-year-old child. The organ doses were measured with thermoluminescent detectors and then used to calculate effective doses. Patient exposure with EOS was then compared to dose levels reported for conventional radiological systems. Image quality was assessed in terms of spatial resolution and different noise contributions to evaluate the detector's performances of the system. The spatial-frequency signal transfer efficiency of the imaging system was quantified by the detective quantum efficiency (DQE). RESULTS: The use of a protective apron when the medical staff or parents have to stand near to the cubicle in the radiological room is recommended. The estimated effective dose to patients undergoing a full spine examination with the EOS system was 290μSv for an adult and 200 μSv for a child. MTF and NPS are nonisotropic, with higher values in the scanning direction; they are in addition energy-dependent, but scanning speed independent. The system was shown to be quantum-limited, with a maximum DQE of 13%. The relevance of the DQE for slot-scanning system has been addressed. CONCLUSIONS: As a summary, the estimated effective dose was 290μSv for an adult; the image quality remains comparable to conventional systems.

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How to recognize, announce and analyze incidents in internal medicine units is a daily challenge that is taught to all hospital staff. It allows suggesting useful improvements for patients, as well as for the medical department and the institution. Here is presented the assessment made in the CHUV internal medicine department one year after the beginning of the institutional procedure which promotes an open process regarding communication and risk management. The department of internal medicine underlines the importance of feedback to the reporters, ensures the staff of regular follow-up concerning the measures being taken and offers to external reporters such as general practioners the possibility of using this reporting system too.

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