Both primary and secondary liver cancers are common and the majority of patients are not eligible for surgical resection or a liver transplant, which are considered the only hope of cure. Mortality rates are high and there is a need for alternative treatment options. New forms of local treatment work best on small tumours; large ones, however, remain difficult to treat. Hyperthermia involves heating tumours to 40??-44?? C. The aim is to heat the entire tumour without damaging the surrounding normal tissue. Treating deep seated tumours is technically challenging. Ferromagnetic embolisation hyperthermia (FEH) is a novel method of treating liver tumours. Magnetic microspheres are infused into the hepatic artery and lodge primarily in the tumour periphery. An applied alternating-current magnetic field causes the microspheres to heat. Animal experiments have shown that this is a promising technique. There is a need for modelling of FEH prior to commencement of clinical trials. Analytical and numerical models of tumour heating during FEH treatment are presented here. The models help predict the temperature distributions that are likely to arise during treatment and give insight into the factors affecting tumour and liver heating. The models incorporate temperature-dependent thermal properties and blood perfusion rates of the tissues and a heterogeneous clustering of microspheres in the tumour periphery. Simulations show that the poorly perfused tumours heat preferentially while the liver is effectively cooled by blood flow from the portal vein. A peripheral distribution of heat sources produces a more even temperature field throughout the tumour, compared to a heat source that is centred within the tumour core. Large tumours reach higher temperatures and have higher heating rates, supporting experimental findings. Using temperature-dependent, rather than constant, values for thermal conductivities and blood perfusion rates results in higher temperatures within the tumour. The uneven clustering of microspheres in the tumour periphery leads to a more heterogeneous temperature distribution in the core, but it has less of an effect on the wellperfused liver. The results show that FEH has the potential to effectively treat liver tumours and the technique merits further investigation.

Both primary and secondary liver cancers are common and the majority of patients are not eligible for surgical resection or a liver transplant, which are considered the only hope of cure. Mortality rates are high and there is a need for alternative treatment options. New forms of local treatment work best on small tumours; large ones, however, remain difficult to treat. Hyperthermia involves heating tumours to 40??-44?? C. The aim is to heat the entire tumour without damaging the surrounding normal tissue. Treating deep seated tumours is technically challenging. Ferromagnetic embolisation hyperthermia (FEH) is a novel method of treating liver tumours. Magnetic microspheres are infused into the hepatic artery and lodge primarily in the tumour periphery. An applied alternating-current magnetic field causes the microspheres to heat. Animal experiments have shown that this is a promising technique. There is a need for modelling of FEH prior to commencement of clinical trials. Analytical and numerical models of tumour heating during FEH treatment are presented here. The models help predict the temperature distributions that are likely to arise during treatment and give insight into the factors affecting tumour and liver heating. The models incorporate temperature-dependent thermal properties and blood perfusion rates of the tissues and a heterogeneous clustering of microspheres in the tumour periphery. Simulations show that the poorly perfused tumours heat preferentially while the liver is effectively cooled by blood flow from the portal vein. A peripheral distribution of heat sources produces a more even temperature field throughout the tumour, compared to a heat source that is centred within the tumour core. Large tumours reach higher temperatures and have higher heating rates, supporting experimental findings. Using temperature-dependent, rather than constant, values for thermal conductivities and blood perfusion rates results in higher temperatures within the tumour. The uneven clustering of microspheres in the tumour periphery leads to a more heterogeneous temperature distribution in the core, but it has less of an effect on the wellperfused liver. The results show that FEH has the potential to effectively treat liver tumours and the technique merits further investigation.

The limitations of renewable energy technologies require that pathways are carefully chosen such that renewable resources are used most effectively in addressing modern energy challenges. Optimized decision-making is particularly challenging for the forest bioenergy sector because of the multitude of potential pathways and because profit is highly sensitive to biomass procurement costs. I assessed energy wood recovery and procurement costs during semi-mechanized selection operations in the tolerant hardwood forests of Ontario. Logging contractors were able to recover unmerchantable sections of branches normally discarded during conventional operations, amounting to 1.3 to 2.7 dry tonnes of additional biomass per hectare. Supply chain scenarios are used to show that the biomass can be brought to market at a cost similar to mechanized operations. The need for prioritization of decentralization, efficiency, and integration with the value-added forest sector is discussed with reference to the relative scarcity and high cost of the forest resource.

The limitations of renewable energy technologies require that pathways are carefully chosen such that renewable resources are used most effectively in addressing modern energy challenges. Optimized decision-making is particularly challenging for the forest bioenergy sector because of the multitude of potential pathways and because profit is highly sensitive to biomass procurement costs. I assessed energy wood recovery and procurement costs during semi-mechanized selection operations in the tolerant hardwood forests of Ontario. Logging contractors were able to recover unmerchantable sections of branches normally discarded during conventional operations, amounting to 1.3 to 2.7 dry tonnes of additional biomass per hectare. Supply chain scenarios are used to show that the biomass can be brought to market at a cost similar to mechanized operations. The need for prioritization of decentralization, efficiency, and integration with the value-added forest sector is discussed with reference to the relative scarcity and high cost of the forest resource.

For the future implementation of high speed communication,safety remains one of the main concerns. To ensurethe safety of new applications, specifically the new 5G antennas,it is crucial to know that they will not cause any harm to thehuman body. There are a few ways to test how safe a systemusing high frequency radiation is but the industry standard is byusing the Specific Absorption Rate (SAR). The SAR is directlycorrelated to the initial temperature rise in the volume exposedto radiation which is what the method used in this report is basedon. The temperature rise in a skin-like phantom due to 5 GHzexposure was recorded using an IR-camera, which in turn wasused to calculate the SAR. The purpose of this report was to testif this method is a valid way of obtaining the peak surface SAR.It was concluded that the method is valid but there are someuncertainties in regards to abstracting the method to far-fieldexposure for our considered frequency. The SAR value that isachieved in this report is 333.4 W/Kg which is high in relationto the SAR-limits in IEEE guidelines, although the set up is notsupposed to reflect a realistic use of the antenna. This is due tothe fact that the waveguide in the setup is close to measurementsample, and has a higher intensity than is to be expected fromreal world applications. The method may be applicable for farfieldexposure with a higher frequency as that would concentratethe measurable heat to the surface of the measurement sampleand would also carry more energy by default. / För all framtida implementering avhöghastighetskommunikation kommer säkerhetsgarantin varaen av de stora frågorna. För att fastställa säkerheten hos nyatillämpningar, specifikt 5G antenner, är det viktigt att vetaatt det är oskadligt för människor. Det finns olika metoderför att påvisa säkerheten i applikationer som använder sig avhögfrekvent strålning men industristandarden är att användaSAR (Specific Absorption Rate). SAR är direkt korrelerat medvärmeutvecklingen i volymen utsatt för strålning vilket är detfaktum denna rapport är baserad på. Temperaturökningeni en skinnliknande fantom från 5 GHz-strålning mättes meden IR-kamera. Detta användes för att räkna ut SAR-värdet.Poängen med rapporten var att testa om denna metod äracceptabel för att räkna ut högsta SAR-värdet i en punkt.Slutsatsen är att denna metod fungerar men det kan finnasproblem med att abstrahera metoden till fjärrfält för vårtilltänka frekvens. Det uppnådda SAR-värdet är 333.4 W/Kgvilket är högt jämfört med IEEE-standarden, detta är på grundav att uppställningen inte är tänkt att återspegla en realistisksituation. Antennen är för nära fantomen och intensiteten ärockså högre än vad som används i vanliga fall. Metoden kanmöjligtvis användas vid fjärrfältstrålning vid högre frekvenseri och med att detta leder till en värmeökning koncentrad vidytan. Dessutom har högre frekvenser högre energi vilket innebären större värmeökning. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

Différentes techniques de chirurgie mini-invasive permettent aujourd’hui d’effectuer les procédures d'ablation de tumeurs. La cryochirurgie est une de ces techniques et fonctionne grâce à une technique de décompression très rapide de l'argon à l’extrémité d’une sonde en forme d'aiguille. La planification pré-opératoire de ce type d’intervention est très difficile pour le chirurgien, qui doit se représenter mentalement la disposition finale des aiguilles par rapport à la position des structures anatomiques complexe. Une sur-ablation ou une sous-ablation peuvent entraîner des complications donc, devant le besoin crucial d'une telle planification, dans cette thèse nous nous sommes concentrés sur la planification pré-opératoire automatisée de la cryochirurgie,avec les objectifs de assister le chirurgien grâce à une prédiction plus réaliste des zones d'ablation et proposer automatiquement un placement d'aiguille avec un risque minimal pour le patient dans un délai acceptable pour une utilisation en salle d'opération. / There exist several minimally invasive techniques to perform tumor ablation procedures.Cryosurgery is one of these techniques and works by decompressing very rapidly the argon gas through a needle-like probe. It is hard for the surgeons to imagine final results and plan the surgery in advance in a complicated anatomical environment. Over-ablation or under ablation may result in complications during the treatment. So, due to a crucial need for having such a planning tool, in this thesis we focused on an automated pre-surgical planning for cryosurgery with goals to support the physician by utilizing a more realistic prediction of ablation zones and proposing a needle placement setup with a close to minimum risk to the patient and an optimal coverage of the tumor by the iceball in an acceptable time for the use in the operation room.