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21.
  • Abdiu, Avni, 1963- (författare)
  • Growth regulation in sarcomas : studies in vivo and in cell culture
  • 1999
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Sarcomas are malignant tumors of mesenchymal origin, and can arise in soft-tissue and in bones. It has been suggested that the abnormal growth regulation in sarcoma cells may be due to an autocrine mechanism, in which the cells are stimulated by an endogenous production of growth factors. Platelet-derived growth factor (PDGF) has been detected in sarcomas, and may be one of the growth factors important for sarcoma growth.PDGF, originally discovered in platelets, is produced by, and binds to, a variety of cells. PDGF plays several roles both in normal conditions and in disease.Suramin is a polyanionic drug with antineoplastic activities, and is known to dissociate growth factors from their receptors. Suramin has been shown to inhibit growth in several tumors and tumor cell lines; however, some tumor cells have been unaffected, or even stimulated, by suramin.The present work was performed in order to a) examine the effects of suramin on sarcoma growth in vivo; b) investigate the kinetics of extravascularly administered PDGF in vivo; c) establish and characterize human sarcoma cells in vitro, including their relation to PDGF; d) evaluate the effects of suramin on sarcoma growth in vitro; e) compare the effects of PDGF on sarcoma growth in vivo and in vitro.Suramin was shown to inhibit growth of two different human osteosarcoma xenografts grown in nude mice. The action is believed to be mainly cytostatic, as the tumors continued to grow, albeit at a lower pace: the tumors of the suramin treated mice had a volume of one-third or less than the untreated ones. The percentage of cells in S and G2-M cell cycle phases was increased by suramin treatment, suggesting a selective effect of the drug in the S and G2 period.Blood and serum levels of 125I, after extravascular administration of 125I-PDGF-AB by intraperitoneal, intramuscular or subcutaneous injection in mice, were found to rise to a maximum 2-4 hours after injection. The levels of radioactivity persisted over several hours. Precipitiation of serum with 10% trichloracetic acid revealed that more than 50% of the radioactivity was in a macromolecular form. Gel chromatography of the serum showed that a major portion of the radioactive material in the circulation had the same molecular size as the original 125I-PDGF-AB.Eight cell lines derived from malignant fibrous histiocytomas (MFH) were established and characterized. A heterogeneity in the morphology of the MFH cell lines was noted. This heterogeneity was also reflected in the expression of mRNA for PDGF, transforming growth factor-alpha (TGF-/alpha/) and their receptors, ability to grow in serumfree media and secretion of PDGF into growth media. Two cell lines, able to grow in serum-free medium, coexpressed MRNA for PDGF, TGF-/aplpha/ and their receptors, suggesting that they may be regulated in an autocrine manner. However, other cell lines, unable to grow in a serum-free medium, also displayed this coexpression of mRNA. The simultaneous expression of a growth factor and its receptor is therefore not generally indicative of an autocrine mechanism.All cell lines, unable to grow in a serum-free medium, were growth inhibited by high-dose suramin (200 ug/ml). The two cell lines, previously noted to grow under serum-free conditions, were not affected by the high-dose suramin treatment. The finding that only serum-dependent human MFH cell lines were inhibited by high doses of suramin indicates that serum dependence in vitro may predict sensitivity of sarcoma cells to suramin.Two human sarcoma xenografts, one osteosarcoma and one malignant fibrous histiocytoma, were treated with human PDGF-AB when grown in nude mice. No effects on tumor growth were noted, although immunohistochemical studies revealed an expression of PDGF receptors. Furthermore, both sarcomas were markedly stimulated by PDGF-AB in vitro. It is concluded that mechanisms or factors other than available PDGF were limiting the growth of the examined tumors in vivo.
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22.
  • Abelius, Martina, 1980- (författare)
  • Immunological interactions between mother and child during pregnancy in relation to the development of allergic diseases in the offspring
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Background: Pregnancy and allergic disease have both been postulated as T-helper 2 (Th2) phenomena. Thus, the increased propensity of allergic mothers to mount Th2-responses might generate favourable effects on the maintenance of pregnancy, but might also be unfavorable, as fetal exposure to a strong Th2 environment could influence the immune development in the offspring to a Th2-like phenotype, favouring IgE production and possibly allergy development later in life. The influence of the intrauterine environment on the immunity and allergy development in the offspring needs to be further investigated.Aim: The aim of this thesis was to explore the Th1/Th2 balance in allergic and non-allergic women during pregnancy and its influence on the shaping of the Th1/Th2 profile in the neonate and the development of allergic diseases in the offspring.Material and methods: The study group included 20 women with and 36 women without allergic symptoms followed during pregnancy (gestational week 10-12, 15-16, 25, 35, 39) and 2 and 12 months postpartum, and their children followed from birth to 6 years of age. The circulating Th1-like chemokines CXCL9, CXCL10, CXCL11, Th2-like chemokines CCL17, CCL18 and CCL22, and the allergen-induced secretion of interleukin-4 (IL-4), IL-5, IL-10, IL-13, Interferon-γ (IFN-γ), CXCL10 and CCL17 were measured by Luminex and ELISA. The allergen-specific and total IgE levels were quantified using ImmunoCAP Technology. mRNA expression of Th1-, Th2-, Treg- and Th17-associated genes were measured by PCR arrays and real-time PCR.Results: We found that sensitised women with allergic symptoms had increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy as compared with postpartum. The non-sensitised women without allergic symptoms had elevated cat-induced IL-5 and IL-13 responses and lower birch- and cat-induced IFN-γ during pregnancy, but similar IgE levels as compared with postpartum.Maternal total IgE levels during and after pregnancy correlated with cord blood (CB) IgE and CCL22 levels (regardless of maternal allergy status). Circulating CXCL11, CCL18 and CCL22 levels during pregnancy and postpartum correlated with the corresponding chemokine levels in the offspring at various time points during childhood. Maternal IL-5 expression in peripheral blood mononuclear cells (PBMC) was associated with neonatal Galectin-1, and placental p35 expression was negatively associated with neonatal Tbx21 expression. Increased mRNA expression of CCL22 in cord blood mononuclear cells (CBMC), and increased CCL17 and CCL22 levels in CB were observed in children later developing allergic symptoms and sensitisation as compared with children who did not. Development of allergic symptoms and sensitisation were associated with increased total IgE, CCL17, CCL18 and CCL22 levels during childhood.Conclusions: Maternal allergy was associated with a pronounced Th2 deviation during pregnancy, shown as increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy, possibly exposing their fetuses to a particular strong Th2 environment during gestation.Correlations were shown between the maternal immunity during pregnancy and the offspring’s immunity at birth and later during childhood, indicating an interplay between the maternal and fetal immunity.Allergy development during the first 6 years of life was associated with a marked Th2 deviation at birth and a delayed down-regulation of this Th2-skewed immunity during childhood.
23.
  • Aboulaich, Nabila, 1976- (författare)
  • Expanding role of caveolae in control of adipocyte metabolism proteomics of caveolae
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The primary function of adipose tissue is to store energy in the form of triacylglycerol, which is hydrolyzed to fatty acids to supply other tissues with energy. While insulin promotes the storage of triacylglycerol, catecholamines stimulate its hydrolysis. The development of type II diabetes is strongly associated with obesity, indicating a role of triacylglycerol metabolism in the pathogenesis of diabetes. Caveolae are plasma membrane invaginations found in most cells but are highly abundant in adipocytes. Insulin receptors are localized in caveolae and their function depends on intact caveolae structures. In the present thesis work, mass spectrometry-based methodology allowed identification of a number of new proteins and their posttranslational modifications in caveolae of human adipocytes. Variable N-terminal acetylation and phosphorylation of caveolin-1α and caveolin-1β were identified, which might regulate the function of caveolae. The transcription regulator protein PTRF was identified as the major caveolae associated protein. Specific proteolytic modifications of PTRF at the cytosolic surface of caveolae and phosphorylation on nine serine and one threonine residues were identified. Moreover, insulin induced translocation of PTRF from the plasma membrane to the nucleus. PTRF was previously shown to regulate the activity of both RNA polymerase I and polymerase II, thus a role of PTRF in mediating the anabolic action of insulin on protein synthesis and gene transcription is proposed.PTRF was also involved in an extranuclear function in the hormonal regulation of triacylglycerol metabolism in caveolae. PTRF was colocalized with the triacylglycerol regulator proteins perilipin and hormone-sensitive lipase (HSL) in the triacylglycerol-synthesizing caveolae subclass. We showed that, while perilipin was translocated to the plasma membrane, both PTRF and HSL were translocated from the plasma membrane to the cytosol as a complex in response to insulin. The perilipin recruited to the plasma membrane was highly threonine phosphorylated. By mass spectrometry, three phosphorylated threonine residues were identified and were located in an acidic domain in the lipid droplet targeting domain of perilipin. The insulin-induced recruitment of perilipin to the plasma membrane might, therefore be phosphorylation-dependent. Isoproterenol, which stimulates hydrolysis of triacylglycerol, induced a complete depletion of perilipin B from the plasma membrane, suggesting a function of perilipin B to protect newly synthesized triacylglycerol in caveolae from being hydrolyzed by HSL. The location of PTRF and HSL was not affected by isoproterenol, indicating that insulin is acting against a default presence of PTRF and HSL in caveolae.Taken together, this thesis expands our knowledge about caveolae and provided valuable information about their involvement in novel roles, particularly in the hormonal regulation of triacylglycerol metabolism.
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24.
  • Abrahamsson, Thomas, 1968- (författare)
  • Can Lactobacillus Reuteri Prevent Allergic Disease in Early Childhood?
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Background: An altered microbial exposure may be partly responsible for the increase of allergic diseases in populations with a western lifestyle. Activation of the immune system by microbes early in life is probably required for an accurate maturation of the immune system. Probiotics, live bacteria which are considered to confer health when ingested, have been suggested to prevent eczema and sensitisation infants.Aim: The general aim of this thesis was to assess the effect of oral supplementation with the probiotic bacterium Lactobacillus reuteri (L. reuteri) in infancy on the development of allergic disease and sensitisation during the first 2 years of life and to examine mechanisms possibly underlying eventual effects on allergic manifestations.Subjects: The thesis is based on results obtained from a prospective double-blind placebo-controlled multicenter trial, comprising 232 families with allergic disease, of whom 188 completed the study.Methods: The families were recruited at the antenatal clinic, and the mothers received L. reuteri ATCC 55730 (1 x 108 colony forming units) or placebo daily from gestational week 36 until delivery. Their babies then continued with the same study product from birth until 12 months of age and were followed up for another year. The primary outcomes were allergic disease, with or without positive skin prick test or circulating IgE to food allergens. Bacterial counts and prevalence were assessed in maternal breast milk and faeces and infant faeces, employing conventional cultivation methods. Cytokines and IgA antibodies were analysed in colostrum and mature milk from the mothers with ELISA, and Na/K- ratio in breast milk with ion selective electrodes. Circulating Th1/Th2-associated chemokines were analysed in cord and peripheral blood in the infants with Luminex or ELISA technique.Results: The incidence of eczema was similar, 36% in the treated versus 34% in the placebo group. The L. reuteri group had a lower cumulative incidence of IgE-associated allergic disease, 20% versus 35% (p=0.04), and less IgE-associated eczema during the second year, 8% versus 20% (p=0.02). The prevalence of L. reuteri was higher during the first year of life in stool samples from infants, as well as in colostrum, in the active as compared to the placebo treated group. Colostrum from L. reuteri supplemented mothers had lower levels of TGF-β2, and low levels of this cytokine were associated with less sensitisation. Low Th1- and high Th2-associated chemokine levels preceded allergic disease. The presence of L. reuteri in stool was associated with lower levels of the Th2-associated chemokines CCL17 and CCL22 and higher levels of the Th1-associated CXCL11.Conclusion: Although a preventive effect of probiotics on infant eczema was not confirmed, the L. reuteri treated infants had lower incidence of IgE-associated allergic disease at two years of age, and therefore possibly run a reduced risk to develop later respiratory allergic disease. The mechanisms underlying this effect require further elucidation.
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25.
  • Abtahi, Jahan, 1965- (författare)
  • Bisphosphonates and implants in the jaw bone
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Insertion of metal implants in bone is one of the commonest of all surgical procedures. The success of these operations is dependent on the fixation of the implants, which, in turn, depends on the strength of the bone that holds them. If the quality of the bone holding the implant could be improved locally, surgical procedures would become simpler and rehabilitation would become faster. Bisphosphonates are anti-resorptive drugs that act specifically on osteoclasts, thereby maintaining bone density and strength. Once released from the surface of a coated implant, bisphosphonates reduce osteoclast activity, thereby changing the balance of bone turnover in favor of bone formation, leading to a net gain in local bone density. During the last decades, the effects of bisphosphonate treatment on the stability of implants have been tested in several clinical and animal studies, but not in human jaws. This may be because it has been suggested that there is a link between the use of bisphosphonates (especially those given intravenously) and a condition called osteonecrosis of the jaw (ONJ). The pathophysiology and treatment of ONJ is controversial. The difficulty in treating ONJ has highlighted the importance of prevention.The overall aim of the present thesis was to evaluate the effect of local and systemic use of bisphosphonates on bone tissue. Could a thin, bisphosphonate-eluting fibrinogen coating improve the fixation of metal implants in the human jaw? Would it be possible to reproduce ONJ and prevent the development of this condition in an animal model?In two clinical studies, a total number of 96 implants were inserted in 21 patients. In a randomized trial with a paired design, one implant in each pair was coated with a thin fibrinogen layer containing two bisphosphonates (pamidronate and ibandronate). The bisphosphonate-coated implants showed better stability as measured by resonancefrequency analysis. Radiographic intraoral films also showed less bone loss. Three animal models were developed. In a study comparing local and systemic effects of bisphosphonates, zoledronate-coated screws inserted in rats showed better fixation in spite of a drug treatment that is known to induce ONJ-like lesions when given systemically. In another rat model, ONJ-like lesions were reproducibly induced at sites of tooth extraction whereas there were no signs of bone cell death in uninjured sites. Finally, rat experiments showed that the development of ONJ-like lesions after tooth extraction could be prevented by early mucoperiosteal coverage.In conclusion, a thin, bisphosphonate-eluting fibrinogen coating can improve the fixation of dental implants in human bone. This may lead to new possibilities in orthopaedic surgery and dentistry. The pathophysiology of ONJ is strongly linked to bone exposure in combination with drugs that reduce resorption.
26.
  • Abu-Zidan, Fikri M. (författare)
  • Role of platelet-activating factor in sepsis and shock : an experimantal study
  • 1995
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Objectives: To study the role of platelet-activating factor (PAF) on cardiovascular and pulmonary dysfunction in sepsis and shock.Design: Experimental study. Setting: Trauma research unit, university department of surgery, Sweden.Material: 76 juvenile domestic pigs. Interventions: The effects of a specific PAF receptor antagonist (BB-882) on haemodynamics and on PAF-induced haemodynamic changes were studied (n = 16). BB-882 was given as pretreatment in non-hypotensive Escherichia coli endotoxaemia (n = 9), during resuscitation after severe haemorrhagic shock (n = 7), hefore post-ischaemic shock which was induced by clamping the aorta above the coliac axis for 45 minutes (n = 8), and as pretreatment in post-haemorrhage septic shock: (n = 6). BB~882 groups were compared with controi groups having the same number of animals which received vehicle instead.Major outcome measures: Heart rate, intravascular pressures, cardiac output, pulmonary and systemic vascular resistance, arteriai blood gas tensions, lung thorax compliance, serum lactic acid and blood sugar concentrations, and packed cell volume.Results: BB-882 effectively counleracted the PAF-induced response on the mean systemic and pulmonary arteriai pressures. lt reduced the rise in pulmonary and systemic vascular resistance and improved the cardiac output in non-hypotensive and post-haemorrhage septic shock when given as pretreatment. lt reduced the hypertension in non-hypotensive sepsis and the hypotension in post-haemorrhage septic shock. BB-8B2 did not infiuence the endotoxin-induced hypoxia or reduced lung thorax compliance in non-hypotensive sepsis and post-haemorrhage septic shock. It did not improve the mean arterial pressure or the cardiac output in haemorrhagic shock alone but it reduced the systemic vascular resistanc'e and was associated with tachycardia and acidosis. It did not affect the post-ischaemic shock after clamping the aorta.Conclusion: PAF is a major mediator of the cardiovascular, but not pulmonary dysfunction in sepsis whether associated with shock or not, while its role on the cardiovascular dysfunction in haemorrhagic and post-ischaemic shock is small.
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27.
  • Addelyan Rasi, Hamideh, 1975- (författare)
  • Empowering Women in the Middle East by Psychosocial Interventions Can provision of learning spaces in individual and group sessions and teaching of coping strategies improve women’s quality of life?
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Background: This study set out to construct a conceptual framework that can be used in social work with women in the Middle East and other settings where women have limited access to resources, which, as a result, limits their decision-making capacity. The framework has both an empirical and a theoretical base. The empirical base comprises data from two intervention projects among Iranian women: single mothers and newly married women. The theoretical base is drawn from relevant psychological and social work theories and is harmonized with the empirical data. Psychosocial intervention projects, based on learning spaces for coping strategies, were organized to assess if Iranian women could use a problemsolving model (i.e. focused on cognition and emotion simultaneously) to effectively and independently meet challenges in their own lives and improve their quality of life.Methods: Descriptive qualitative and quasi-experimental quantitative methods were used for data collection and analysis. Forty-four single mothers and newly married women from social welfare services were allocated to nonrandomized intervention and comparison groups. The intervention groups were invited to participate in a 7-month psychosocial intervention; the comparison groups were provided with treatment as usual by the social welfare services. The WHOQOL-BREF instrument was used to measure quality of life, comparing each intervention groups’ scores before and after the intervention and with respective comparison groups. In addition, content analysis and constant comparative analysis were performed on the qualitative data collected from the participants before, during and after the intervention.Results: The results of the quasi-experimental study show significant and large effect sizes among the women exposed to the intervention. Small and not statistically significant effect sizes were observed in the women provided with traditional social welfare services. Accordingly, teaching coping strategies can be a means to improve the quality of life of women in societies where gender discrimination is prevalent. The qualitative findings from the Iranian projects illustrate a process of change —socio-cognitive empowerment— with regard to thinking, feeling and acting among women during and after the intervention. The women developed a number of mental capacities essential to coping and life management. All women used the model effectively, and consequently, made more deliberate decisions to improve their life situations.Conclusion: The practical lessons from the Iranian projects highlight the possibilities of empowering women through fostering mindfulness and deliberate decision making as well as achieving consciousness. This study provides provisional evidence that psychosocial intervention projects, based on learning spaces for coping strategies, can help many clients to achieve their goals and improve their quality of life, and that this psychosocial intervention project can be a useful model for social work practice with women in the Middle East. The conceptual framework can help social workers to bridge the gap between theory and practice: that is, to draw from existing social work theories and, through the psychosocial intervention model, better apply this knowledge in their practical work with women in challenging social environments.
28.
  • Adell, Gunnar, 1953- (författare)
  • Indicators of colorectal cancer prognosis and response to preoperative radiotherapy
  • 2000
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Colorectal cancer is one of the three most common malignant diseases in Sweden, with about 5,000 new cases each year. Thirty-five percent of these are rectal cancer, for which local recurrence after surgery has been a serious problem. The five-year survival rate in colorectal cancer has improved from about 40% in 1960 to 55% in 1995. Adjuvant chemotherapy of colon cancer, preoperative radiotherapy and improved surgical techniques in rectal cancer have contributed to the improved  results. To select patients best suited for pre- or postoperative therapy, we need indicators of both prognosis and response to therapy.Using antibodies against cytokeratin, we found that 39% of patients with colorectal carcinoma that had penetrated the muscularis propria but without lymph-node metastases by routine light microscopy, had got micrometastases. Survival among patients with micrometastases was not significantly different from that among patients without such metastases.We also identified subsets of tumour-infiltrating mononuclear cells and studied their pattern of distribution in relation to regressive tumour areas and Dukes class. Our interpretation is that the subsets of tumourinfiltrating mononuclear cells change with advancing Dukes class, indicating gradual deterioration of the local immune control.We also investigated the interaction between p53, Ki-67, apoptosis and the outcome in rectal cancer with and without short-term preoperative radiotherapy. The expression of nuclear p53 protein seemed to be a significant predictive factor for local treatment failure after preoperative radiotherapy. Low tumour cell proliferation measured with Ki-67 in the preoperative biopsy correlated with improved local control and disease-free survival after preoperative radiotherapy.High apoptotic index was associated with improved local control of rectal cancer even without pre-operative radiotherapy, whereas local control of tumours with low and intermediate apoptotic index was significantly improved by preoperative radiotherapy.In conclusion, micrometastases in regional lymph nodes are an interesting phenomenon but with limited prognostic value. The subsets of tumour-infiltrating mononuclear cells change with advancing Dukes class, and its seems that the local immune control is gradually broken down. In rectal cancer, p53 expression, tumour proliferation measured with Ki-67 and apoptotic index seem to be interesting indicators of rectal cancer prognosis and response to preoperative radiotherapy.
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29.
  • Adolfsson, Ann-Sofie, 1960- (författare)
  • Miscarriage Women’s Experience and its Cumulative Incidence
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Many women experience miscarriage every year. Every fourth woman who has given birth reports that she has previous experience of miscarriage. In a study of all women in the Swedish Medical Birth Register 1983-2003, we found that the number of cases of self reported miscarriage had increased in Sweden during this 21 year period. This increase can be explained by the introduction of sensitive pregnancy tests around 1990, as well as an increase in the mean age of the mothers, by approximately 3 years, during the observation period. The risk of miscarriage is 13% with the first child. With subsequent pregnancies, the risk of miscarriage is 8%, 6% and 4% with the second, third and fourth child, respectively.Thirteen of these women who had suffered a recent miscarriage were interviewed four months later, and their feelings of guilt and emptiness were explored. Their experience was that they wanted their questions to be answered, and that they wanted others to treat them as the mothers to be that they felt themselves to be. They also experienced the need for time to grieve their loss.Measurement of grief by means of the Perinatal Grief Scale (PGS) is used in research but has also been proposed for clinical use. We have translated this psychological instrument to Swedish, back-translated and tested it in a small pilot study. In a randomized controlled study, women with early miscarriage were allocated, either to a structured visit (study group) or a regular visit (control group) to a midwife. The structured visit was conducted according to the Swanson caring theory. We could conclude that the structured visit had no significant effect on grief compared to the regular visit, as measured using the PGS. However, women with the sub-diagnosis missed abortion have significantly more grief four months after early miscarriage, regardless of visit type.We also performed a content analysis of the tape-recorded structured follow-up visit. The code-key used was Bonanno and Kaltman’s general grief categorization. Women’s expression of grief after miscarriage was found to be very similar to the grief experienced following the death of a relative. Furthermore, the grief was found to be independent of number of children, women’s age, or earlier experience of miscarriage.Conclusions: Every fourth woman who gives birth reports that she has also experienced early miscarriage. The experience of these women is that they have suffered a substantial loss and their reaction is grief similar to that experienced following the death of a relative.
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30.
  • Adolfsson, Emelie, 1985- (författare)
  • Lithium formate EPR dosimetry for accurate measurements of absorbed dose in radiotherapy
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Lithium formate has shown to be a material with properties suitable for electron paramagnetic resonance (EPR) dosimetry, among them up to 7 times higher sensitivity compared to alanine, which is a well-established EPR detector material for dose determinations in radiotherapy.The aim of this thesis was to further investigate the properties of lithium formate and develop the dosimetry system towards applications in radiotherapy. The intrinsic efficiency for energies of relevance to brachytherapy and the signal stability were investigated. The dosimetry system was expanded to include a smaller dosimeter model, suitable for measurements in dose gradient regions. An individual sensitivity correction method was applied to the smaller dosimeters to be able to perform dose determinations with the same precision as for the larger ones. EPR dosimetry in general is time consuming and effort was spent to optimize the signal readout procedure regarding measurement time and measurement precision.The system was applied in two clinical applications chosen for their high demands on the dosimetry system: 1) a dosimetry audit for external photon beam therapy and 2) dose verification measurements around a low energy HDR brachytherapy source.The conclusions drawn from this thesis were: dose determinations can be performed with a standard uncertainty of 1.8-2.5% using both the original size dosimeters and the new developed smaller ones. The dosimetry system is robust and useful for applications when high measurement precision and accuracy is prioritized. It is a good candidate for dosimetry audits, both in external beam therapy and brachytherapy.
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