| Magnetic nanoparticle hyperthermia is an important kind of tumor hyperthermia developed in recent years which receives widespread attention due to its effectiveness.This technology uses the therapeutic heat from magnetic nanoparticles(MNPs)under an external alternating magnetic field to heat tumor tissues and ablate tumor cells.Although magnetic hyperthermia has many advantages related with its low side effects,there are some key issues that need to be solved before it can be widely used.This thesis begins with an investigation of the theory used for magnetic hyperthermia analysis,then studies the multi-physics coupling methods and key influencing factors for this technique,and finally presents a thorough research on nanofluid injection strategy and its optimization problems using the previous results.The main works and findings are summarized as follows:(1)It reveals the relationship of different thermogenesis mechanism for MNPs under alternating magnetic fields,investigates the apoptotic characteristics for different tumor cells during magnetic hyperthermia,and presents an analysis of the coupling method for multi-physics and simulation based on finite element method for verification of the heat treatment.On this basis,a model considering MNPs is proposed to optimize the properties of MNPs by using a proposed analysis method based on critical temperature profile during magnetic hyperthermia.This research results demonstrate that the treatment temperature profile can be controlled in a desired range when this method is used to optimize the properties of MNPs before therapy.(2)It investigates the influences of different key factors in a magnetic hyperthermia treatment.This thesis proposes an improved biological heat transfer equation which considers the behavior of MNPs inside living tissues and then uses it to analyze the impact of MNPs clusters on the therapeutic temperature profile.In addition,it evaluates the effects of the inhomogeneous magnetic field of a solenoid device on magnetic hyperthermia,derives the numerical model for blood vessels considering heat transfer in biological tissues,and uses this model to investigate the effect of blood vessel properties on the temperature profile during magnetic hyperthermia.The results show that the improved bioheat transfer equation can effectively compensate the error in the effective dissipation of MNPs that exists between theoretical models from the literature and experimental results.In addition,the show that MNPs with low Curie temperature can significantly improve the uniformity and effectiveness of treatment temperature profile for a tumor with vascularization.(3)It studies the mass transfer and diffusion behaviors for magnetic fluids in interstitial tissue before and after injection,deduces and presents the key theoretical mathematical models for subsequent work.The proposed numerical models are then used to investigate the impact of the injection strategy on the magnetic fluid spatial distribution and therapeutic temperature profile during an ideal injection process,and to study the influence due to the injection rate by comparing the ideal model and experimental results.The investigation results show that reasonable optimization of the injection strategy of magnetic fluid can significantly improve the effective treatment area for magnetic thermotherapy.(4)It proposes an optimization method of the injection strategy for irregularly shaped tumors.A final algorithm is determined by comparing test functions,and is then applied to the optimization method of injection strategy in terms of the treatment temperature profile during magnetic hyperthermia.This method makes combined use of the finite element method and an optimization algorithm to optimize the therapeutic effect for irregular tumors.The results of optimization analysis demonstrate that the proposed method can significantly improve the treatment temperature profile for irregular tumors and that it has low dependence on the initial value. |
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