| 1. |
- Olofsson, Lennart, 1952-
(författare)
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Energy and intensity modulated radiation therapy with electrons
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years intensity modulated radiation therapy with photons (xIMRT) has gained attention due to its ability to reduce the dose in the tissues close to the tumour volume. However, this technique also results in a large low dose volume. Electron IMRT (eIMRT) has the potential to reduce the integral dose to the patient due to the dose fall off in the electron depth dose curves. This dose fall off makes it possible to modulate the dose distribution in the direction of the beam by selecting appropriate electron energies. The use of a computer based energy selection method was examined in combination with the IMRT technique to optimise the electron dose distribution. It is clearly illustrated that the energy optimisation procedure reduces the dose to lung and heart in a breast cancer treatment. To shape the multiple electron subfields (beamlets) that are used in eIMRT, an electron multi leaf collimator (eMLC) is needed. However, photons produced in a conventional electron treatment head could penetrate such an added eMLC, thus producing an undesirable dose contribution. The leakage levels normally achieved are acceptable for standard single electron field treatments but could become unacceptably high in eIMRT treatments where a lot of small subfields are combined. To limit this photon contribution, the photon MLC (xMLC) was used to shield off large parts of the photon leakage. The effect of this xMLC shielding on the reduction of photon leakage, the electron beam penumbras, and electron output (dose level), was studied using Monte Carlo methods for different electron treatment head designs. The use of helium as a mean to reduce the electron scatter in the treatment head, and thus the perturbating effect of the xMLC on electron beam penumbra and output, was also investigated. This thesis shows that the effect of the xMLC shielding on the electron beam penumbra and output can be made negligible while still obtaining a significantly reduced x-ray leakage dose contribution. The result is a large gain in radiation protection of the patient and a better dynamic range for the eIMRT dose optimisation. For this optimisation a computer based electron energy selection method was developed and tested on two clinical cases.
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| 2. |
- Braunerhielm, Lotta
(författare)
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Plats för kulturarv och turism : Grythyttan - en fallstudie av upplevelser, värderingar och intressen
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the tension between cultural heritage and tourism development. A case study was carried out in Grythyttan, a cultural-historical place, located in the municipality of Hällefors in Bergslagen. The central aim of the study is to explore, understand and interpret the tensions between cultural heritage and tourism. The ambition has been to focus upon the consequences of the increased interest from the tourism industry in cultural heritage and the increased interest from the cultural heritage sector in tourism and on creating heritage-based experiences. Grythyttan represents the place where the complex of problems is illustrated. The aim involves a description of characteristics of cultural heritage and tourism and how they are experienced with regards to a historical-geographical perspective. This is considered in contrast to the increased commercialization in society. The method has been to study how the place, cultural heritage and tourism are experienced by different actors, those who live, work and visit the place. The three actor groups who were studied were producers, consumers/visitors and locals. The producers were representatives of both the tourism and cultural heritage sector and from the municipality.What has happened at the place is characteristic of our time, i.e. the commercialization of places and an adjustment to the tourism market. Grythyttan has been transformed into a tourism destination with a profile of meal. The whole municipality has purposely erased an old identity associated with the history of coalmining and ironworks. This has contributed to a clear distinction between a ‘place’ and a ‘destination’. This also highlights two different perspectives of the actors, those who bring out the importance of the heritage and those who look upon the heritage and the place from a commercial perspective. Visitors are offered a commercial place and an experience of the meal destination but are not offered the story of ‘the place’.The concluding remarks are that the ‘place’ Grythyttan is associated with a strong identity anchored in its historical-geographical context and strongly associated with locals and the heritage sector. The cultural heritage gives way to tourism and meal. Heritage is not a part of and not ‘given place’ in the tourism destination of meal.
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| 3. |
- Högström, Magnus, 1956-
(författare)
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Vitamins, fatty acids, physical activity and peak bone mass
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Osteoporosis is a disease characterized by low bone mineral density, deteriorated bone microstructure and increased fracture risk. About 50% of all women and 25% of all men will have an osteoporotic fracture. Given that there is no effective cure in established osteoporosis, prevention is of high importance. Bone mineral density (BMD) is accumulated during childhood and adolescence with a peak at about 20 years of age. Peak BMD has been suggested to explain at least half of the variation in BMD up to old age. Thus, to increase peak BMD could decrease the risk of later fractures. The purpose of the present thesis was to investigate the influence of physical activity, vitamins A and D, and fatty acids on peak bone mass in men. The influence of physical activity on bone accrual was studied in two cohorts. In the first cohort 46 ice hockey players, 18 badminton players and 27 controls, all 17 years of age at baseline, were followed for four years. During the follow up the badminton players gained more bone mass at the hip compared to both the ice hockey players and controls. In the second cohort the associations between physical activity and BMD were investigated in 62 female and 62 male young medical students. The estimated high impact activity per week was associated with bone mass at all sites in the male medical students (r=0.27-0.53, p<0.05). In the female cohort different estimates of physical activity were not related to bone mass at any site. In both males and females correlations between bone mass and body constitution parameters were observed. Levels of vitamin D3, vitamin D2, retinol, retinol-binding-protein-4 (RBP-4) and fatty acids were measured in 78 young men with a mean age of 22.6 years. BMD at various sites were measured using Dual-Energy X-ray absorptiometry. Levels of vitamin D3 showed a significant positive association with all BMD sites and also lean body mass (r=0.23-0.35, p<0.05). Levels of vitamin D2, however, showed a significant negative correlation with BMD of the total body (r=-0.28, p=0.01) and spine (r=-0.27, p=0.02). There was also a significant negative relationship between levels of vitamin D3 and D2 (r=-0.31, p=0.006). Concentrations of n-3 (omega-3) fatty acids showed a positive association with BMD at the total body (r=0.27, p=0.02) and spine BMD (r=0.25, p=0.02). There was also a positive association between levels of n-3 fatty acids and changes in BMD of the spine between 16 and 22 years of age (r=0.26, p=0.02). The significant associations found seemed to be related mostly to the concentration of the n-3 fatty acid docosahexaenoic acid. Levels of retinol and RBP-4 were not related to BMD but to levels of osteocalcin, which is a marker of bone formation. This association disappeared when adjusting for the influence of abdominal fat mass. In summary, the present thesis suggests that many modifiable factors may influence the accumulation of peak bone mass in males, such as physical activity, vitamins, and fatty acids. Further studies are needed to investigate whether optimizing these factors in youth may decrease the risk of osteoporosis later in life.
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| 4. |
- Marits, Per, 1977-
(författare)
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On CD4+ T Lymphocytes in Solid Tumours
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with recognition and elimination of tumours by T lymphocytes and their use in adoptive immunotherapy.The first tumour-draining lymph node; the sentinel node, is identified by peritumoural injection of a tracer. This is the hypothesised location for the activation of tumour-reactive lymphocytes. Accordingly, proliferation and IFN-γ production in response to autologous tumour extract was detected in sentinel nodes from patients with colon and urinary bladder cancer. Reactivity in metastatic nodes was generally lower or absent, but the non-responsiveness could be subdued in long-term cultures by addition of tumour antigen and IL-2. A novel padlock-probe based method was developed for measuring the T cell receptor Vβ repertoire. Common Vβ gene expansions were detected in tumour-infiltrating lymphocytes and sentinel nodes. Thus, tumour antigens are recognised in sentinel nodes by Th1 lymphocytes, resulting in a clonally expanded cell population that can be further propagated ex vivo.Regulatory T cells (Tregs) may contribute to tumour-induced immunosuppression. Immunohistochemical stainings against the pan-T cell marker CD3 and Treg marker FOXP3 was performed on tumour tissue from 20 historical urinary bladder cancer patients. The ratio of FOXP3+ to CD3+ cells was lower in patients alive 7 years post-cystectomy, suggesting that Tregs in bladder cancer have prognostic implications.Lymphocytes were isolated from sentinel nodes from sixteen patients with advanced or high-risk colon cancer. In vitro expansion with addition of autologous tumour extract and IL-2 mainly promoted the outgrowth of CD4+ Th1 lymphocytes, which were safely re-transfused to the patients. Four patients responded with complete tumour regression. Survival time in the Dukes’ D patients was significantly increased compared with conventionally treated controls (2.6 versus 0.8 years; p=0.048).In conclusion, human solid tumours are recognised in sentinel nodes and in vitro expanded sentinel node-acquired CD4+ T lymphocytes seem useful in the treatment of patients with disseminated cancer.
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| 5. |
- Owais, Owais, 1971-, et al.
(författare)
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Circular Monopole Antenna Stability with Regard to Ground Plane Size
- 2008
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Ingår i: <em>Proc. of the 2008 International Symposium on Antenna and Propagation (ISAP'08)</em>, Taiwan, Oct. 27-30, 2008.. ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- Wireless communications for short range and high data rate require wideband operation that necessitates the demand for miniaturized, low cost and low profile antennas. Miniaturized planar monopole antennas provide wide impedance bandwidth for wireless personal area network applications [1]. Different monopole shapes have been considered and a lot of research has been made to improve the bandwidth and reduce the size by changing the antenna shape [2]-[4]. The radiator part has been the main focus of research to find a shape that provides wide bandwidth [3]-[4], as well on studying how the ground plane affects the bandwidth of antennas. Wide bandwidth has been obtained by bevelling the radiator [5] and use of a modified ground plane [6]. Planar monopoles with parasitic elements and slots give also a wideband [7]. It has been documented that the finite size of the ground plane is an important factor for the antenna performance [8]. Planar monopoles have a benefit of being low cost and compatible to printed circuit board (PCB) allowing compact design. Since the ground plane is coplanar with the antenna, it necessitates that its stability should not change when integrated in PCB with different ground plane size of adjoining circuits. To avoid pre-tuning and achieve cost effectiveness, system development requires a stable planar monopole antenna that can be integrated without depreciation of its performance. This paper studies in detail the effect of ground plane dimension, width and length, on the stability of the coplanar monopole antenna, by changing the ground plane size while keeping feedline and feedap constant. The parametric investigation supported by simulation and experimental results is conducted in this paper to give insights to the stability issue that have not been reported before.
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| 6. |
- Rydell-Karlsson, Monica
(författare)
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Knowledge Acquisition in Patients with Heart Disease
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim was to evaluate different aspects of the knowledge acquisition process in patients with heart disease. Three different education programs were evaluated.In Paper I 208 patients with systolic heart failure (HF) aged >60 years, were included. They were randomized to the nurse-based outpatient clinic or to the patients´ general practitioners (GP). The aim was to assess effects of a nurse-based management program – intended to increase the knowledge of the HF disease and its self-care – and relate the results to gender and cognitive function. The results showed that the nurse-based outpatient clinic has an important role in patient education, and increases patients´ knowledge about self-care and the disease. The results indicate that females have more to gain than men from such management programs. Patients demonstrating signs of cognitive dysfunction when in hospital did also benefit.In Paper II 224 patients, aged <75 years suffering from an acute AMI or who had underwent coronary artery by-pass grafting, were randomized to intervention (an expanded cardiac rehabilitation program) or to control (usual care). The aim was to investigate the effect of an expanded cardiac rehabilitation program on psychosocial characteristics including depression, anxiety, and quality of life (QoL) in type D and non-type D coronary artery disease (CAD) patients. The results show that an expanded rehabilitation program significantly reduces type D score, improves QoL, and decreases self-estimated depression and anxiety in CAD patients in the highest quartile of type D score.In Paper III and IV 182 patients with chronic heart failure (CHF) were included and referred to the nurse-based outpatient clinic. They were randomized to intervention (patients decided on how they should be informed and by which information technique) or to control (the nurse decided according to usual routine).The aim in Paper III was to compare patient-based selection of information with nurse-based selection of information in patients with HF and to evaluate the effects on knowledge acquisition, QoL, visits to the outpatient clinic, drug therapy and readmissions. Patients had fewer visits to the nurse-based outpatient clinic and a trend to a more flexible diuretic regimen, if patients were involved in the decision on how to be informed. Both groups increased QoL, knowledge their doses of relevant medication, and readmissions did not differ between the two groups.The aim in Paper IV was to compare patient-based and nurse-based New York Heart Association (NYHA) classification and its relation to grade of depression and knowledge acquisition in patients with HF. The results show a mismatch between the NYHA classifications performed by patients respectively by the nurse. Furthermore, patients in a depressed mood at baseline had more clinical events during the first year after hospitalization due to CHF. However, there was no difference in knowledge acquisition between patients in a depressed mood as compared to patients in a normal mood.The conclusion is that information given at a nurse-based outpatient clinic has an important role in patient education. Females and patients with in-hospital cognitive dysfunction had the greatest gains Patients who are involved in the decision on how to be informed had fewer visits to the nurse-based outpatient clinic. The fewer visits did not affect knowledge, QoL, readmissions, or medical treatment in a negative way. Patients assessed a higher NYHA class than a nurse. Patients who were depressed had an increased incidence of clinical events during the first year after hospitalisation due to HF. There was no difference in knowledge acquisition between patients in a depressed mood as compared to patients in a normal mood. An expanded rehabilitation program significantly reduces type D score, improves quality of life, and decreases self-estimated depression and anxiety in patients with CAD in the upper quartile of type D score.
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