| 1. |
- Adamus-Górka, Magdalena, 1977-
(författare)
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Improved dose response modeling for normal tissue damage and therapy optimization
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis is focused on the development and application of dose response models for radiation therapy. Radiobiological models of tissue response to radiation are an integral part of the radiotherapeutic process and a powerful tool to optimize tumor control and minimize damage to healthy tissues for use in clinical trials. Ideally, the models could work as a historical control arm of a clinical trial eliminating the need to randomize patents to suboptimal therapies. In the thesis overview part, some of the basic properties of the dose response relation are reviewed and the most common radiobiological dose-response models are compared with regard to their ability to describe experimental dose response data for rat spinal cord using the maximum likelihood method. For vascular damage the relative seriality model was clearly superior to the other models, whereas for white matter necrosis all models were quite good except possibly the inverse tumor and critical element models. The radiation sensitivity, seriality and steepness of the dose-response relation of the spinal cord is found to vary considerably along its length. The cervical region is more radiation sensitive, more parallel, expressing much steeper dose-response relation and more volume dependent probability of inducing radiation myelitis than the thoracic part. The higher number of functional subunits (FSUs) consistent with a higher amount of white matter close to the brain may be responsible for these phenomena. With strongly heterogeneous dose delivery and due to the random location of FSUs, the effective size of the FSU and the mean dose deposited in it are of key importance and the radiation sensitivity distribution of the FSU may be an even better descriptor for the response of the organ. An individual optimization of a radiation treatment has the potential to increase the therapeutic window and improve cure for a subgroup of patients.
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| 2. |
- Andisheh, Bahram, 1967-
(författare)
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Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New methods of high dose delivery, such as intensity modulated radiation therapy (IMRT), stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), hadron therapy, tomotherapy, etc., all make use of a few large fractions. To improve these treatments, there are three main directions: (i) improving physical dose distribution, (ii) optimizing radiosurgery dose-time scheme and (iii) modifying dose response of tumors or normal tissues.Different radiation modalities and systems have been developed to deliver the best possible physical dose to the target while keeping radiation to normal tissue minimum. Although applications of radiobiological findings to clinical practice are still at an early stage, many studies have shown that sublethal radiation damage repair kinetics plays an important role in tissue response to radiation.The purpose of the present thesis is to show how the above-mentioned directions could be used to improve treatment outcomes with special interest in radiation modalities and dose-time scheme, as well as radiobiological modeling. Also for arteriovenous malformations (AVM), the possible impact of AVM network angiostructure in radiation response was studied.
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| 3. |
- Atterhög, Mikael, 1962-
(författare)
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The effect of competition and ownership policies on the housing market
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation consists of five studies presented in seven essays. The overall objectives are to investigate the extent and consequences of competition on the rental housing market as well as the importance of national government policies for the substitute good, i.e. owner-occupied housing. However, each essay also has specific objectives. Due to the characteristics of the housing market, one should not expect competition to be very fierce. The market characteristics are, for instance, capital-intensive, complicated and time-consuming construction processes as well as a limited supply of land in many areas. In fact, firms have a lot to gain from colluding and to avoid e.g. price wars. It is therefore theoretically more likely that housing companies will engage in “functional” or “strategic” competition such as the quality of housing services. Essay I and IV analyze the unique municipal housing market in Sweden where apartment rents are determined by negotiations between the local municipal company and the local Union of Tenants. A regression analysis is applied on data from 30 municipalities. There was a strong correlation between apartment rents at local municipal markets and the level of “external” competition (measured by the price level on the market for single-family owner occupied housing), but not with “internal” competition (measured by the market share of the municipal housing company) or the capital expenditure of the municipal housing company (presumed to reflect historical construction and renovation costs for the apartments). The dissertation also investigates the consequences on rents (essay II) and on the quality of housing services (essay III) from a local Swedish municipal housing company selling a substantial part of its apartment stock (15-40 percent) and thereby theoretically creating more competition. These essays use a quasi-experimental methodology whereby the development of the housing market in a privatization town is compared with the development in a very similar comparison town. It is found that privatization has lead to lower rents in the short- and medium-term in six out of seven privatization towns. The development of the quality of housing services was more related to the performance of each individual company and not a specific category of companies. In essay V, these results are merged and developed further. Essay VI presents a wide range of policies available for governments wishing to increase access to home ownership for low-income households and thereby increasing the pressure on rental housing companies to reduce rents. A systematic overview of policies is provided based on the four distinct time periods of a typical ‘housing career’ of a household; i.e. down payment accumulation stage, transaction stage, ownership stage and selling stage. It is found that many policies are required to meet the specific and differing needs of households for governments wishing to encourage home ownership. Essay VII describes that home ownership rates have increased in almost all industrialized countries during the period from World War II until mid-1990s. The essay analyses the implications of government policies and some other factors (e.g. national wealth, income distribution) on home ownership rates in 13 industrialized countries during the period 19702000. A fixed-effect model is applied on a panel data set. The most important result is that a statistically significant and positive correlation between government support and home ownership rates was found although this is only a preliminary conclusion since data was scarce.
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| 4. |
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| 5. |
- Lind, Leili, 1954-
(författare)
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Towards Effortless Use of Information Technology in Home Healthcare with a Networked Digital Pen
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- When care is moved from the hospital to the home the demands for high quality care still remain. For problems arising from the geographical separation of patients and professional caregivers, information and communication technology may offer important solutions. The overall aim of this thesis was to describe relevant requirements, to design and implement an IT-based system, and finally to evaluate the system’s influence on symptom control and support for both patients/next-of-kin and professional caregivers in advanced home healthcare. Of importance were needs in basic as well as advanced home healthcare, as were usability perspectives of both patients and professional caregivers. Requirement areas such as security, mobility, and responsibility, which should be considered when monitoring patients in the home, were identified. A prototype system for everyday assistance for diabetes patients was designed, and a system for frequent pain assessment for palliative home healthcare patients using a pain diary, digital pen and mobile Internet technology, was developed and evaluated through a qualitative content analysis approach. Twelve palliative cancer patients and six professional caregivers participated. The data collected included an ease-of-use questionnaire, and interviews with patients, spouses and professional caregivers. Patients expressed increased and improved contact with the caregivers, increased participation in their own care, a sense of increased security, and easiness in using the equipment in spite of severe illness and difficulties in comprehending the technology and system intervention. The professional caregivers showed a shifting outlook towards the pain assessment method; an initial cautious outlook due to low expectations of the patients’ abilities to use the pain assessment method and the caregivers’ own reluctance to use the system and change their way-of-working. Despite this, the professional caregivers experienced positive outcomes in terms of an increased awareness of pain, and positive patient influences including increased participation in their care, increased security and improved changes in pain treatment as a response to reported pain assessments. In conclusion, the networked digital pen system provided an effortless method for pain assessment and had positive influences on the care. The results imply that digital pen technology is suitable for the assessment of symptoms by palliative patients since these patients often have a limited capacity to handle technology due to their state of health.
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| 6. |
- Lind, Thomas, 1986-
(författare)
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Inertia in Sociotechnical Systems : On IT-related Change Processes in Organisations
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of new information technology (IT) in an organisation is one way of changing the conditions for how tasks and work processes can be designed and performed, as well as how people in the organisation interact with each other. Today, many Swedish workers rely completely on IT to be able to perform their jobs, while experiencing a combination of continuous and intermittent IT-related changes that affect this ability.The introduction of new or updated IT systems in an organisation is an example of what is referred to as an IT-related change process in this thesis. Because IT has become such an integral part of modern organisations, many change processes in organisations are simultaneously enabled and constrained by the IT systems involved in a change process. In this thesis, I introduce the concept of inertia in sociotechnical systems to analyse IT-related change processes in organisations, and how achieving the goals of these processes is complicated by organisational, social, and physical aspects in addition to technology.The context of this thesis is the Swedish public sector domains of health-care and higher education, and the result of research studies and experiences from four action research projects in these settings. The contribution of this thesis adds to the contributions of the included papers through the definition of inertia in sociotechnical systems and its subsequent application. The thesis shows that the concept of inertia in sociotechnical systems can be used to understand IT-related change processes as changes to the characteristics of a sociotechnical system, and, in the context of organisations, how these processes affect and are affected by an organisation’s characteristics. This is illustrated in the thesis through the application of the concept on examples of IT-related change processes from the included papers and research projects. In addition, the thesis shows that the use of vision seminar methods can benefit Swedish organisations, since new IT is often introduced without clearly defined, expressed, understood, and accepted goals.
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| 7. |
- Littmarck, Sofia, 1983-
(författare)
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Barn, föräldrar, välfärdsstat : Den politiska debatten om föräldrautbildning och föräldrastöd 1964-2009
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The political debate concerning parent education and parenting support between 1964 and 2009 has been scrutinized in this study in the light of the development of and changes in the welfare state. The investigation is based upon the analysis of official government inquiries and parliamentary papers dealing with parent education and parenting support. This study analyzes the different choices in the organization of welfare relevant to children and the family for which political actors have argued, and it examines the views on the relations between children, parents, family and the welfare state that were expressed in the argumentation. Parent education and parenting support aim at changing the living conditions of children by means of the parents. The study shows that the interest in this type of investment has been shared by both the political left and center-right, but from different arguments and political visions on how welfare for children and families with children should be organized, as well as from different views of the role of parent education and parenting support in the welfare.
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| 8. |
- Löfgren, Håkan
(författare)
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Outcome and bone grafts in surgical treatment of cervical disc disease : A clinical evaluation using MRI, radiostereometry and measurements of microcirculation and the quality of life
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis was to evaluate the outcome after surgical treatment of cervical disc disease and the influence of different bone grafting methods.192 patients were studied, of which 149 were treated surgically. They all presented with radiculopathy and/ or myelopathy, and were subjected to an anterior cervical discectomy and fusion as described by Cloward, except for 8 patients operated with a posterior decompression.43 patients due for surgery were prospectively randomized to fusion with either auto-, allo- or xenograft. 33 of these patients were then monitored by radiostereornetric analysis (RSA) after 6, 12 and 24-50 (mean 37) months, including conventional radiography at the final follow-up. All 43 patients were examined clinically, including pain rating pre- and postoperatively with a final follow-up by an unbiased observer. Mobility could be demonstrated by RSA in 9 patients after one year and at the final follow-up in 6, with no difference between bone grafts. Conventional radiography showed final mobility in only 1 out of these 6 patients. The clinical results were not influenced by whether mobility could be demon strated or not. There was a tendency towards better clinical results in the patients fused with an autograft.13 patients operated without bone graft had a less favourable clinical outcome compared with 11 patients operated with autograft, retrospectively studied 6- 9 years postoperatively.The normal postoperative course was followed prospectively in 25 consecutive patients by MRI and clinical reviews, preoperatively and 3 days, 3, 6, 12 and 24 months postoperatively. The results demonstrated that the decompression by an anterior procedure should not be evaluated by MRI until at least 3 months postoperatively. This is because surgical debris behind the bone dowel is impossible to distinguish from remaining osteophytes or disc fragments. MRI-findings of foraminal narrowing were common postoperatively among patients with no remaining radiculopathy. A rim sign was permanent with high signal enhancement around the bovine xenograft after i. v. contrast, indicating fibrous healing.Surgically treated patients experienced a pain reduction as measured by visual analogue pain scales (VAS) and showed an improvement in clinical findings, when followed by unbiased observers at least 2 years after surgery. Some recurrence of pain and other symptoms was common 3 to 6 months postoperatively. The improvement in quality of life measured by Sickness Impact Profile (SIP) in 43 operated patients was mainly temporary, even if a sustained improvement after 2 years was observed among the operated patients that were referred directly to us.No corresponding changes in pain, clinical findings or SIP were seen among 41 conservatively treated patients, matched for gender and age.Measurements of microcirculation and electromyography in the trapezius muscles during increased static load before and 9 months after surgery (27 patients) showed a tendency towards increased microcirculation and increased muscle activation. There was a more evident response on the less painful side, as well as among the 8 patients operated using a posterior approach.
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| 9. |
- Nilsson, Johan, 1971-
(författare)
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Accurate description of heterogeneous tumors for biologically optimized radiation therapy
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, a model of tissue oxygenation is presented, that takes into account the heterogeneous nature of tumor vasculature. Even though the model is rather simple, the resulting oxygen distributions agree very well with clinically observed oxygen distributions for most tumors and healthy normal tissues. The model shows that the vascular density may not describe the oxygenation of a tissue sufficiently well, unless the heterogeneity of the vascular system is taken into account. Based on the oxygen distributions from the tissue model, the associated radiation response at low and high doses can be determined. The radiation response of heterogeneous tumors should preferably be described by two clonogen compartments, one resistant and one sensitive, dominating the response at high and low radiation doses, respectively. Furthermore, each compartment should be characterized by the effective radiation resistance and the effective clonogen number. The resistant-sensitive model of radiation response has been analyzed in great detail. It accurately describes the response of severely heterogeneous tumors, both at low and high doses and LET values. The effective response parameters are given as integrals, averaged over the whole spectrum of radiation resistance. The parameters can also be determined from clinically established dose-response relations. The main properties of the dose-response relation for a generally heterogeneous tumor is described in some detail. The normalized dose-response gradient has been generalized to take heterogeneities in both dose delivery and radiation response into account. This quantity is important for accurate treatment plan optimization using intensity modulated radiation therapy for individual patients.
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| 10. |
- Olsson, Thomas, 1963-
(författare)
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Risk Prediction at the Emergency Department
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The severity of illness was scored in a cohort of 11751 non-surgical patients presenting at the Emergency Department (ED) during 12 consecutive months and followed for 4.7 years. The scoring system Rapid Acute Physiology score (RAPS) (including blood pressure, respiratory rate, pulse rate and Glasgow coma scale) was calculated for all arrivals at the ED. The RAPS system was also additionally developed by including the peripheral oxygen saturation and patient age, resulting in the new Rapid Emergency Medicine Score, (REMS). REMS was superior to RAPS in predicting in-hospital mortality according to ROC-curve analysis. An increase of one point in the 26 point REMS scale was associated with an Odds ratio of 1.40 for in-hospital death (95% CI 1.36-1.45, p<0.0001). Similar results were obtained in the major patient groups (chest pain, stroke, coma, dyspnea and diabetes). The association between REMS and length of stay in hospital was modest. Charlson Co-morbidity Index could add prognostic information to REMS in a long-term (4.7 years), but not in a short-term perspective (3 and 7 days). REMS was shown to be as powerful a predictor of in-hospital mortality as the more complicated APACHE II. REMS at the ED could also predict long-term mortality (4.7 years) in the total cohort (Hazard ratio 1.26, p<0.0001).REMS is a potentially useful prognostic tool for non-surgical patients at the ED, regarding both in-hospital and long-term mortality. It is less complicated to use than APACHE II and has equal predictive accuracy.
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