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| 2. |
- Abul-Kasim, Kasim, et al.
(författare)
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Optimization of Radiation Exposure and Image Quality of the Cone-beam O-arm Intraoperative Imaging System in Spinal Surgery.
- 2012
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Ingår i: Journal of Spinal Disorders and Techniques. - 1539-2465. ; 25:1, s. 52-58
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: Retrospective study. OBJECTIVES: To optimize the radiation doses and image quality for the cone-beam O-arm surgical imaging system in spinal surgery. SUMMARY OF BACKGROUND: Neurovascular compromise has been reported after screw misplacement during thoracic pedicle screw insertion. The use of O-arm with or without navigation system during spinal surgery has been shown to lower the rate of screw misplacement. The main drawback of such imaging surgical systems is the high radiation exposure. METHODS: Chest phantom and cadaveric pig spine were examined on the O-arm with different scan settings: 2 were recommended by the O-arm manufacturer (120 kV/320 mAs, and 120 kV/128 mAs), and 3 low-dose settings (80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs). The radiation doses were estimated by Monte Carlo calculations. Objective evaluation of image quality included interobserver agreement in the measurement of pedicular width in chest phantom and assessment of screw placement in cadaveric pig spine. RESULTS: The effective dose/cm for 120 kV/320 mAs scan was 13, 26, and 69 times higher than those delivered with 80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs scans, respectively. Images with 60 kV/40 mAs were unreliable. Images with 80 kV/80 mAs were considered reliable with good interobserver agreement when measuring the pedicular width (random error 0.38 mm and intraclass correlation coefficient 0.979) and almost perfect agreement when evaluating the screw placement (κ value 0.86). CONCLUSIONS: The radiation doses of the O-arm system can be reduced 5 to 13 times without negative impact on image quality with regard to information required for spinal surgery.
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| 3. |
- Bauer, Brigitte, 1978, et al.
(författare)
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Metal nanoparticles amplify photodynamic effect on skin cells in vitro
- 2011
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Optical Interactions with Tissue and Cells XXII; San Francisco, CA; 24-26 January 2011. - : SPIE. - 1605-7422. - 9780819484345 ; 7897
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.
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| 4. |
- Carvalho Bittencourt, André, 1984-, et al.
(författare)
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A data-driven approach to diagnostics of repetitive processes in the distribution domain : Applications to gearbox diagnosticsin industrial robots and rotating machines
- 2014
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Ingår i: Mechatronics (Oxford). - : Elsevier. - 0957-4158 .- 1873-4006. ; 24:8, s. 1032-1041
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a data-driven approach to diagnostics of systems that operate in a repetitive manner. Considering that data batches collected from a repetitive operation will be similar unless in the presence of an abnormality, a condition change is inferred by comparing the monitored data against an available nominal batch. The method proposed considers the comparison of data in the distribution domain, which reveals information of the data amplitude. This is achieved with the use of kernel density estimates and the Kullback–Leibler distance. To decrease sensitivity to disturbances while increasing sensitivity to faults, the use of a weighting vector is suggested which is chosen based on a labeled dataset. The framework is simple to implement and can be used without process interruption, in a batch manner. The approach is demonstrated with successful experimental and simulation applications to wear diagnostics in an industrial robot gearbox and for diagnostics of gear faults in a rotating machine.
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| 5. |
- Carvalho Bittencourt, André, 1984-
(författare)
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Modeling and Diagnosis of Friction and Wear in Industrial Robots
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High availability and low operational costs are critical for industrial systems. While industrial equipments are designed to endure several years of uninterrupted operation, their behavior and performance will eventually deteriorate over time. To support service and operation decisions, it is important to devise methods to infer the condition of equipments from available data.The monitoring of industrial robots is an important problem considered in this thesis. The main focus is on the design of methods for the detection of excessive degradations due to wear in a robot joint. Since wear is related to friction, an important idea for the proposed solutions is to analyze the behavior of friction in the joint to infer about wear. Based on a proposed friction model and friction data collected from dedicated experiments, a method is suggested to estimate wear-related effects to friction. As it is shown, the achieved estimates allow for a clear distinction of the wear effects even in the presence of large variations to friction associated to other variables, such as temperature and load.In automated manufacturing, a continuous and repeatable operation of equipments is important to achieve production requirements. Such repetitive behavior of equipments is explored to define a data-driven approach to diagnosis. Considering data collected from a repetitive operation, an abnormality is inferred by comparing nominal against monitored data in the distribution domain. The approach is demonstrated with successful applications for the diagnosis of wear in industrial robots and gear faults in a rotating machine.Because only limited knowledge can be embedded in a fault detection method, it is important to evaluate solutions in scenarios of practical relevance. A simulation based framework is proposed that allows for determination of which variables affect a fault detection method the most and how these variables delimit the effectiveness of the solution. Based on an average performance criterion, an approach is also suggested for a direct comparison of different methods. The ideas are illustrated for the robotics application, revealing properties of the problem and of different fault detection solutions.An important task in fault diagnosis is a correct determination of presence of a condition change. An early and reliable detection of an abnormality is important to support service, giving enough time to perform maintenance and avoid downtime. Data-driven methods are proposed for anomaly detection that only require availability of nominal data and minimal/meaningful specification parameters from the user. Estimates of the detection uncertainties are also possible, supporting higher level service decisions. The approach is illustrated with simulations and real data examples including the robotics application.
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| 6. |
- Dahlstrand, Ursula, et al.
(författare)
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TEP under general anesthesia is superior to Lichtenstein under local anesthesia in terms of pain 6 weeks after surgery : results from a randomized clinical trial
- 2013
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 27:10, s. 3632-3638
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Tidskriftsartikel (refereegranskat)abstract
- Persistent pain is common after inguinal hernia repair. The methods of surgery and anesthesia influence the risk. Local anesthesia and laparoscopic procedures reduce the risk for postoperative pain in different time perspectives. The aim of this study was to compare open Lichtenstein repair under local anesthesia (LLA) with laparoscopic total extraperitoneal repair (TEP) with respect to postoperative pain. Between 2006 and 2010, a total of 389 men with a unilateral primary groin hernia were randomized, in an open-label study, to either TEP (n = 194) or LLA (n = 195). One patient in the TEP group and four in the LLA group were excluded due to protocol violation. Details about the procedure and patient and hernia characteristics were registered. Patients completed the Inguinal Pain Questionnaire (IPQ) 6 weeks after surgery. [The study is registered in ClinicalTrials.gov (No. NCT01020058)]. A total of 378 (98.4 %) patients completed the IPQ. One hundred forty-eight patients (39.1 %) reported some degree of pain, 22 of whom had pain that affected concentration during daily activities. Men in the TEP group had less risk for pain affecting daily activities (6/191 vs. 16/187; odds ratio [OR] 0.35; 95 % CI 0.13-0.91; p = 0.025). Pain prevented participation in sporting activities less frequently after TEP (4.2 vs. 15.5 %; OR 0.24; 95 % CI 0.09-0.56; p < 0.001). Twenty-nine patients (7.7 %) reported sick leave exceeding 1 week due to groin pain, with no difference between the treatment groups. Patients who underwent the laparoscopic TEP procedure suffered less pain 6 weeks after inguinal hernia repair than those who underwent LLA. Groin pain affected the LLA patients' ability to perform strenuous activities such as sports more than TEP patients.
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| 8. |
- Eklund, Mona, et al.
(författare)
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Effectiveness of an intervention to improve day centre services for people with psychiatric disabilities
- 2014
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Ingår i: Australian Occupational Therapy Journal. - : John Wiley & Sons. - 0045-0766 .- 1440-1630. ; 61:4, s. 268-275
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Tidskriftsartikel (refereegranskat)abstract
- Background/aim: Day centres for people with psychiatric disabilities need to be evaluated for effectiveness in order to provide the best possible support. This study aimed at investigating the effectiveness of a tailor-made intervention to improve day centre services for people with psychiatric disabilities.Methods: The intervention was devised to bridge identified gaps in the services and lasted for 14 months. Eight centres were allotted to the intervention (55 attendees) or comparison condition (51 attendees). Fidelity to the intervention and major events in the day centres were assessed. The outcomes were degree of meaningfulness found in the day centre occupations, satisfaction with the rehabilitation received, satisfaction with everyday occupations and quality of life.Results: The fidelity to the intervention was good, but more positive events, such as new occupational opportunities, had taken place in the comparison units. No differences were identified between the intervention and the comparison group regarding changes from baseline to the 14-month follow-up in perceived meaningfulness among day centre occupations, satisfaction with everyday occupations or quality of life.Conclusions: The intervention seemed ineffective, but the positive events in the comparison group resembled the measures included in the tailor-made interventions. This first intervention study in the day centre context has hopefully helped to generate hypotheses and methods for future research.
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| 9. |
- Geber, Therese, et al.
(författare)
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Eye lens dosimetry for interventional procedures - Relation between the absorbed dose to the lens and dose at measurement positions
- 2011
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 46:11, s. 1248-1251
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Konferensbidrag (refereegranskat)abstract
- This study investigated the relationship between the absorbed dose to the lens of the eye and the absorbed dose at different measurement positions near the eye of interventional radiologists. It also visualised the dose distribution inside the head, both when protective eyewear were used and without such protection. The best position for an eye lens dosimeter was found to be at the side of the head nearest to the radiation source, close to the eye. Positioning the dosimeter at the eyebrow could lead to an underestimation of the lens dose of as much as 45%. The measured dose distribution showed that the absorbed dose to the eye lenses was high compared to the other parts of the head, which stresses the importance of wearing protective eyewear. However, many models of eyewear were found to be deficient as the radiation could slip through at several places, e.g. at the cheek. The relationship between the absorbed dose to the lens and the kerma-area-product (P-KA) delivered to the patient was also studied. (C) 2011 Elsevier Ltd. All rights reserved.
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| 10. |
- Gidlöf-Gunnarsson, Anita, 1957, et al.
(författare)
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Comparative studies on railway and road traffic noise annoyances and the importance of number of trains
- 2011
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Ingår i: 11th International Congress on Noise as a Public Health Problem (ICBEN), 24-28 July, 2011, London, UK.
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Konferensbidrag (refereegranskat)abstract
- Railway noise is perceived as less annoying than road traffic noise, both in terms of general annoyance and sleep disturbances according to dose-response relationships from meta-analyses. However, findings in recent years from Japanese studies show, unlike most European studies, that railway noise is perceived as more annoying than road traffic noise at sound levels >LAeq,24h 55 dB. This applies particularly to the Japanese Shinkansen express trains as well as conventional trains. Several of the Japanese studies have been done in areas with a very large number of trains (about 500-800 trains/day). In the present study, the following research questions were asked: How does a large number of trains affect noise annoyance and can the differences between Japanese studies (railway noise more annoying than road traffic noise) and European studies (railway noise less annoying than road traffic noise) in part be due to major differences in the number of trains? Socio-acoustic surveys (n=1689) were conducted in residential areas exposed to railway noise with different number of trains (124 trains/day vs. 481 trains/day) and road traffic noise (LAeq,24h 45-65 dB in all areas) The findings show that the number of trains/day, and not only the equivalent sound levels influence how railway noise is perceived. When the number of trains is very large, (481 trains/day), the proportion who are annoyed and report disturbed activities is significantly higher than in a situation with fewer trains (124 trains/day) at equal sound levels and in comparison to road traffic noise >LAeq,24h 55 dB.
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