The ability of an individual to withstand elevated head-to-toe gravitoinertial (+Gz) forces is determined by the capacity of their body to maintain sufficient head-level arterial pressure. Recent studies have shown a relationship between resting blood-vessel stiffness and an individual’s +Gz-tolerance, although the mechanisms behind this relationship are unclear. The aim of this project is to determine whether or not +Gz-tolerance is affected by a change inresting vasomotor tone. To evaluate this relationship, seven participants were asked to complete a +Gz-tolerance protocol using a human-use centrifugeon two different occasions. On both visits, gradual onset rate (0.1 G.s−1)and rapid onset rate (3.5 G.s−1) tests were done to evaluate the participants+Gz-tolerance. On one of the two visits, prior to the +Gz-tolerance testing,participants performed a 20-min cycle intervention to induce postexercisehypotension, with the aim of temporarily reducing participants’ resting bloodpressure and vasomotor tone. The cycling intervention was successful atinducing postexercise hypotension, as mean arterial pressure was significantlylower on the cycling visit (P<0.05). +Gz-tolerance was significantly lower(P<0.05) on the cycling visit compared with the non-cycling visit for both theGOR and ROR tests (absolute difference of 0.5 G and 0.25 G, respectively).The effect of the type of test on +Gz-tolerance was not influenced by the effectof the cycling intervention (P>0.05). Being the most documented mechanismlinked to postexercise hypotension, sustained vasodilation was assumed tohave occurred. This would have increased distensibility of the affected vessels,explaining the decrease in +Gz-tolerance. The decrease in +Gz-tolerance wassimilar for both tests, indicating that the baroreflex was not affected by thecycling intervention. Assuming that vasodilation occurred, this study showedthat a decrease in resting vasomotor tone decreased +Gz-tolerance, indicatingthe importance of this variable in the relationship between resting blood-vesselstiffness and an individual’s +Gz-tolerance.

People with cerebral palsy (CP) may develop muscle contractures, which are defined as a loss of joint range due to an increase in passive muscle stiffness [1]. Computer models suggest that intramuscular fat can increase muscle stiffness [2]. There is evidence that children with spastic CP have elevated intramuscular fat fractions, but quantitative estimations of the intramuscular fat fraction are variable [1]. Therefore, a reliable method for in vivo quantification of intramuscular fat is required. The aim of this thesis was to compare two- and three-point Dixon fat-water separation methods, as well as the IDEAL algorithm for intramuscular fat quantification of the gastrocnemius medialis, for both children with CP and typically developed peers. As a reference standard, the water- and fat-only maps resulting from the Philips mDIXONXD turbo-spin-echo sequence were used (Ingenia CX, Philips Healthcare, The Netherlands). It was found that neither of the methods can compare to the reference standard, which is probably due to poor performance of the phase unwrapping algorithm applied on this data. Further studies need to be done in order to better quantify the phase error in multi-echo Dixon MRI.

Neonatal asphyxia is the third largest cause of neonatal mortality in Vietnam, and many of the surviving patients suffer from permanent brain damage. A cooling mattress used for treatment of infants suffering from asphyxia has been shown to have problems with providing a stable body temperature for the patients. The main purpose of this project is to assess potential problems with routines and the use of the most central technical equipment used to treat newborns suffering from asphyxia, as well as constructing a phantom to simulate a newborn infant in the process of cooling. The purpose of the simulation is to investigate new methods of using the cooling mattress to achieve a more stable body temperature when cooling the patient. The project was done at Phu San Hostpial and Vietnam National Children's Hospital in Hanoi, Vietnam. The technical evaluation was conducted with observations, interviews and a question form. The results showed that there were issues with the sensors connected to the ventilators, noise level from alarms and routines concerning sanitation. The phantom was based on a water bottle, an interest heater and a pump to mix the water. It proved not possible to construct a phantom that met the necessary criteria. / Asfyxi hos nyfödda är den tredje största orsaken till neonatal dödlighet i Vietnam, och många av de överlevande får permanenta hjärnskador. En nedkylningsmadrass som används till behandling av nyfödda med asfyxi har visat sig ha problem med att hålla patientens kroppstemperatur stabil. Arbetets huvudsakliga syfte är att undersöka potentiella problem med rutiner och användningen av den viktigaste tekniken vid behandling av nyfödda som lider av asfyxi, samt även konstruera en fantom som ska kunna simulera en nyfödd vid nedkylning. Simuleringen har som syfte att undersöka nya användningsmetoder av nedkylningsmadrassen för att uppnå en mer stabil kroppstemperatur hos patienten. Arbetet gjordes vid Phu San Hospital, och National Children’s Hospital i Hanoi, Vietnam. Utvärderingen av teknikens användning gjordes via observationer, intervjuer och ett frågeformulär. Resultaten sammanställdes för att hitta potentiella förbättringar till teknikens användning. Det framkom problem med sensorerna kopplat till ventilatorerna, ljudnivån från alarmer och rutiner kring sanitering. Fantomet baserades på en vattenflaska, en doppvärmare och en pump som blandade vattnet. Det visade sig inte vara möjligt att konstruera en fantom som uppfyllde alla kriterier med de resurser som var tillgängliga.

In Sweden almost three persons over the age of 65 years dies every daybecause of fall injuries. The overall societal costs of elderly fall accidentswere estimated to to be 14 billion SEK, and if no action is taken this cost isestimated to increase to 22 billion SEK until 2050. The individual decreasein life of quality due to pain, decrease of independence and, for those stillworking, a decrease in income is of course also well worth considering.It is well known that multitasking while walking will decrease attentionon the surroundings and gait behaviour which increases the risk of falling. Itis known that walking uses both sensory input and visual inputs to guide themotion. The visual input prepares the body to adjust itself before a step istaken to optimize the outcome.This study aimed to investigate the effect of multitasking on gaze strategiesand gait performance. Five healthy adults walked over a setup of ramps and astep while performing three different levels of cognitive loading: just walking,walking and performing mental arithmetic’s and walking and scrolling on amobile cell phone.The eye tracking device Pupil Core (Pupil Labs, Berlin, Germany) wasused to capture the gaze points of the participants and Vicon Nexus togetherwith force plates were used to capture data to compute the kinematics of theparticipants during the walking.The results revealed that four out of four participants had a lower ratio ofgaze fixations on objects of interest when scrolling on the phone comparedto just walking, and three out of four participants had a lower ratio of gazefixations on objects of interest when doing mental arithmetic’s compared tojust walking. Simultaneously the gait parameters and kinematics changed in away that might increase the risk of falling. Four out of four participants had adecrease in average stride length and average stride velocity when walkingwhile scrolling on a phone and a decrease in average stride velocity whenperforming mental arithmetic’s compared to just walking. Three out of fourparticipants had a decrease in average stride length when performing mentalarithmetic’s compared to just walking.Since the participant number was low more studies are needed to confirmthese results. The experimental design would benefit from adjustments to tryto separate the effect on gaze behaviour between altered cognitive loading andaltered gait pattern, but are a good base to use for further studies.

In the long distance running community there is currently controversy as a result of the release of Advanced Footwear Technology (AFT) type of shoes. The AFT shoes with performance enhancing mechanical properties are currently used with great success. All of the current world records in long distance running have been set by athletes wearing the novel type of shoes. The new type of shoes have been shown to reduce energetic cost of running but the exact mechanisms of the reduced energetic cost are still unclear. In the research community several hypotheses of mechanisms and performance enhancing features exist. In this thesis the focus was on investigating the performance enhancing feature, energy return and the effect it has on the biomechanical variables, ground reaction force, joint moments and joint power.  For this thesis five male subelite to elite runners were recruited. The participants ran over two force platforms with a controlled running velocity while motion data was recorded with a marker based motion analysis system. The curves from the contact of the foot with the force platform were analysed with the motion analysis software, Visual 3D and the SPM1D statistical package in Matlab.  The results suggest that energy return properties of AFT shoes do affect lower extremity loading. Significant differences in the biomechanical variables GRF, ankle moment and ankle power were seen between high energy return shoes and low energy return shoes. In addition the number of significantly different intervals show a tendency of a pattern, where shoes share the largest amount of significantly different intervals with shoes that are furthest away on the energy return list. However, shoe #4 did not behave according to the energy return ranking. This means that a sole dependency on energy return characteristics was not found.    The knowledge gained from this thesis does not reduce the controversy surrounding the shoes. It does however establish a base for further research in the area of AFT. From that base, further research could create a solid scientific understanding of the shoes, which can be used to justify regulation changes. Regulations with a solid scientific backing would reduce the controversy. / Inom långdistanslöpning finns det för närvarande en kontrovers till följd av lanseringen av skor av typen Advanced Footwear Technology. Advanced Footwear Technology-skor med prestandaförbättrande mekaniska egenskaper används för närvarande med stor framgång. Alla nuvarande världsrekord i långdistanslöpning har satts av idrottare som bär den nya typen av skor. Det har visat sig att den nya typen av skor minskar den energetiska kostnaden för löpning, men de exakta mekanismerna för den minskade energetiska kostnaden är fortfarande oklara. Inom forskarvärlden finns flera hypoteser om mekanismer och prestationshöjande egenskaper. I den här uppsatsen låg fokus på att undersöka den prestationshöjande egenskapen, energiåtergivning, och vilken effekt den har på de biomekaniska variablerna markreaktionskraft, ledmoment och ledeffekt.  För denna uppsats rekryterades fem manliga subelit- till elitlöpare. Deltagarna sprang över två kraftplattformar med en kontrollerad löphastighet medan rörelsedata registrerades med ett markörbaserat rörelseanalyssystem. Kurvorna från fotens kontakt med kraftplattformen analyserades med rörelseanalys-programmet Visual 3D och statistikpaketet SPM1D i Matlab.  Resultaten tyder på att AFT-skor har egenskaper som ger energiåtergivning och som påverkar belastningen på nedre extremiteterna. Signifikanta skillnader i de biomekaniska variablerna GRF, fotledsmoment och fotledskraft sågs i resultaten. Dessutom visar antalet signifikant olika intervall en tendens till ett mönster, där skor delar det största antalet signifikant olika intervall med skor som ligger längst bort på listan över energiåtergivning. Sko #4 uppförde sig dock inte i enlighet med rangordningen för energiåtergivning. Detta innebär att man inte har funnit något beroende av egenskaperna för energiåtervändning.    Den kunskap som erhållits genom denna uppsats minskar inte kontroverserna kring skorna. Den skapar dock en grund för ytterligare forskning inom området Advanced Footwear Technology. Utifrån denna grund kan ytterligare forskning skapa en solid vetenskaplig förståelse för skorna, som kan användas för att motivera ändringar av regler. Ett regelverk med ett gediget vetenskapligt stöd skulle minska kontroverserna.

Medical devices are becoming more and more implemented for use at home and in parallel, the interest from humans in their own health is increasing. Age-related diseases such as diabetes, cancer, and dementia, to name a few, are examples of diseases that with an early diagnosis could be prevented. To find out if there are early indications of the disease in the body, it is necessary to measure biomarkers. These can be measured either invasive or non-invasive and today they are often measurable only clinically at a hospital, but how can people measure these at home by themselves? To investigate this, a literature study has been done with focus on age-related diseases. A total of 49 abstracts were read through to determine relevance to the questions of inquiry and three articles were mainly used in the literature study. It was found that there is research focusing on the use of biomarkers to identify and do earlier diagnosing of age-related diseases. Methodology and technology for measuring glucose to identify diabetes are implemented, and a change in lifestyle can prevent a person from being affected by type 2 diabetes. With this knowledge, it is easier to see opportunities for other diseases by using the same type of method and technology further on. A previously conducted study regarding diabetes focus on dietary variations and physical activity for non-diabetic people. Meanwhile in the cancer and dementia area, where the developments are not as successful, the focus is on earlier diagnosing by combining technologies. In the future, the technology should be developed so that biomarkers can be used as indicators of the diseases cancer and dementia, and not just as a complement to already applied technology such as imaging techniques that are available today.

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With the growing use and complexity of proton therapy, the safety and accuracy of the machines becomes increasing important. This, to be able to deliver the prescribed dose to the target while minimizing the dose to healthy tissue. In this project, machine quality assurance data are analyzed to quantify the existing positional machine uncertainties in the form of deviations from expected value and their effect on the dose accuracy in order to improve precision. The method consisted of two main parts. In the first part, two systems to monitor the measured deviations variations from the machine quality assurance tests were implemented. In the second part, two ways to measure the impact of the positional machine uncertainties were developed. The monitoring systems showed that the uncertainties had shrunken over time or were stable, and that the tolerance limits currently used for the machine quality assurance can be lowered. The measured impact of the positional machine uncertainties showed that a margin of 0.61 mm for treatment room 1 and a margin of 1.02 mm for treatment room 2 was required to compensated for the machine uncertainties. When the uncertainties we reincorporated into a clinical approved robust optimized plan, the result showed no significant change in dose to the different treatment volumes. The result gives the Scandion clinic insight and tools to minimize the impact of machine uncertainties and to be able to improve the precision of future treatments.

When removal of primary tumors is performed by surgery, the surgeon andthe patient would benefit from using intraoperative feedback to evaluate thetumor resection margin. If intraoperative feedback is not provided there isadditional risk of treatment of the tumor. With improvements to the fixationtime of soft tissue, phase-contrast computed tomography (PC-CT) could allow3D intraoperative feedback to the surgeons.The focus of this project has been to develop a method for measuring fixationtime on soft tissue samples and examine ways to decrease the required fixationtime. Furthermore, evaluation of fixatives to achieve image contrast that wouldbe sufficient to accomplish the possibility of intraoperative tumor feedback, inPC-CT images has been performed in this project. / När avlägsnande av primära tumörer utförs av kirurger, skulle både kirurgenoch patienten gynnas av intraoperativ återkoppling för att bedöma resektions-marginalen. Utan intraoperativ återkoppling finns det risk för att yttrligarebehandling av tumören är nödvändig. Med förbättringar inom fixeringstid avmjukvävnad skulle faskontrast-CT möjliggöra 3D intraoperativ återkopplingtill kirurgen.Fokuset inom detta projekt har varit att ta fram en metod för mätning av fixe-ringstid av mjukvävnadsprover och undersöka tillvägagångssätt för att minskaden behövda fixeringstiden. Vidare så har utvärdering av fixeringsvätskor föratt uppnå bildkontrast som skulle vara bra nog att fungera som intraoperativåterkoppling av tumör-information, inom faskontrast-CT utförts i detta projekt.

During the last few years, deep learning-based techniques have made much progress in the medical image processing field, such as segmentation and registration. The main characteristic of these methods is the large demand of medical images to do model training. However, the acquisition of these data is often difficult, due to the high expense and ethical issues. As a consequence, the lack of data may lead to poor performance and overfitting. To tackle this problem, we propose a data augmentation algorithm in this paper to inpaint the tumor on healthy pediatric brain MRI images to simulate pathological images. Since the growth of tumor may cause deformation and edema of the surrounding tissues which is called the 'mass effect', a probabilistic UNet is applied to mimic this deformation field. Then, instead of directly adding the tumor to the image, the GAN-based method is applied to transfer the mask to the image and make it more plausible, both visually and anatomically. Meanwhile, the annotations of the different brain tissues are also obtained by employing the deformation field to the original labels. Finally, the synthesized image together with the real dataset is trained to do the tumor segmentation task, and the results indicate a statistical improvement in accuracy.