Digital breast tomosynthesis is a new technology that provides three-dimensional information of the breast and makes it possible to distinguish the cancer from overlying breast tissues. We are dedicated to optimizing image reconstruction and imaging configuration for a new multi-beam parallel digital breast tomosynthesis prototype system. Several commonly used algorithms from the typical image reconstruction models which were used for iso-centric tomosynthesis systems were investigated for our multi-beam parallel tomosynthesis imaging system. The representative algorithms, including back-projection (BP), filtered back-projection (FBP), matrix inversion tomosynthesis reconstruction (MITS), maximum likelihood expectation maximization (MLEM), ordered-subset maximum likelihood expectation maximization (OS-MLEM), simultaneous algebraic reconstruction technique (SART), were implemented to fit our system design. An accelerated MLEM algorithm was proposed, which significantly reduced the running time but had the same image quality. Furthermore, two statistical variants of BP reconstruction were validated for our tomosynthesis prototype system. Experiments based on phantoms and computer simulations show that the prototype system combined with our algorithms is capable of providing three-dimensional information of the objects with good image quality and has great potentials to improve digital breast tomosynthesis technology. Four methodologies were employed to optimize the reconstruction algorithms and different imaging configurations for the prototype system. A linear tomosynthesis imaging analysis tool was used to investigate blurring-out reconstruction algorithms. Computer simulations of sphere and wire objects aimed at the performance of out-of-plane artifact removal. A frequency-domain-based methodology, relative NEQ(f) analysis, was investigated to evaluate the overall system performance based on the propagation of signal and noise. Conclusions were made to determine the optimal image reconstruction algorithm and imaging configuration of this new multi-beam parallel digital breast tomosynthesis prototype system for better image quality and system performance.

Den psykiska ohälsan ökar stadigt i omvärlden, därav genomgår fler människor psykologiska behandlingar för att öka sitt välmående. Den tidigare forskningen har uppvisat att negativa effekter i samband med en psykologisk behandling existerar. Syftet med genomförandet av studien var att undersöka om det fanns negativa eller oönskade effekter hos personer som genomgått någon evidensbaserad psykologisk behandling samt att undersöka vilka de mest förekommande oönskade effekter var hos den rekryterade gruppen. Studien genomfördes genom en enkätstudie med totalt 63 deltagare (M = 33 år, SD = 8.4, åldersspann 20 - 57 år,67% kvinnor). Instrumentet som användes var The Negative Effects Questionnaire med 32 påståenden, vilka utgör en sex faktorsmodell (symptom, kvalitet, beroende, stigma, hopplöshet och misslyckande). Instrumentet mäter huruvida deltagarna upplevt att behandlingen lett till några negativa eller oönskade effekter. Resultatet på frågeställning A ”Vilka är de mestförekommande biverkningarna hos den rekryterade gruppen?” visar att den mest rapporterade negativa effekten var “känner du dig sorgsen”. Resultatet från frågeställningen B ”Finns det könsskillnader i medelvärden av faktorerna hos NEQ?” visar att kvinnor generellt rapporterat fler biverkningar jämfört med männen. Studien går i linje med tidigare forskning och svarar på samtliga frågeställningar. Studiens låga antal deltagare (N = 63), och dess bekvämlighetsurval gör att studien inte kan generalisera sitt resultat. Spridningen blir inte lika omfattande och representativ som den hade varit med en större urvalsgrupp. / Mental illness is steadily increasing in the world, because of which more people are undergoing psychological treatments to increase their well-being. Previous research has shown that negative effects in connection with a psychological treatment exist. The purpose of conducting the study was to investigate whether there were negative or unwanted effects inpeople who had undergone any evidence-based psychological treatment and to investigate what the most common unwanted effects were in the recruited group. The study was conducted through a questionnaire study with a total of 63 participants (M = 33 years, SD =8.4, age range 20 - 57 years, 67% women). The instrument used was The Negative Effects Questionnaire with 32 statements, which constitute a six-factor model (symptom, quality, dependence, stigma, hopelessness and failure). The instrument measures whether the participants experienced that the treatment led to some negative or unwanted effects. The result of question A shows that the most reported negative effect was "do you feel sad". The results from question B show that women generally reported more side effects compared to men. The study is in line with previous research and answers all questions. The study's low number of participants (N = 63), and its convenience selection means that the study can notgeneralize its results, the spread will not be as extensive and representative as it would have been with a larger sample group.