Sharif Digital Repository

The tumor is a collection of cells (cell mass) caused by the lack or ineffectiveness of cellular proliferation inhibitors. Many types of cancers are associated with the emergence of a tumor, a tissue with specific physiological characteristics. The tumors grow very fast so researchers try to prevent their growth and eventually destroy them. Thermal ablation by MWA(microwave ablation) is a common and minimally-invasive treatment for primary and secondary liver tumors that can not be cured by surgery. During treatment, the tissue is heated by microwaves and at a temperature higher than 50 degree Celsius, destroyed by thermal ablation. In this study, two thermal models have been used to... 

Low frequency Magnetic hyperthermia is a promising cancer treatment technique. It is based on the fact that magnetic nanoparticles (MNPs) placed in an alternating magnetic field release heat.Active research is being done to improve the specific absorption rate (SAR) of MNPs, which could permit the treatment of tumors of a smaller size and could reduce the amount of material that must be injected to treat a tumor of a given size. However, a major technical problem with hyperthermia is the difficulty of heating the targeted tumor to the desired temperature without damaging the surrounding tissues, as the electromagnetic energy must be directed from an external source and penetrates normal... 

The purpose of this study is to estimate the temperature distribution of the internal body organs using electromagnetic waves. When the external electromagnetic field propagates in biological tissues under a process like microwave hyperthermia, the temperature of the tissue at the field concentration area increases. Due to temperature and frequency dependence of the tissue dielectric, the tissue permittivity changes; thus, the electric field scattered by the tissue changes. Therefore, by measuring the field scattered from the object, dielectric changes of the tissue structure can be calculated. Since the biological tissues’ dielectric coefficient at frequencies lower than 2GHz is linear,... 

In the method treatment of thermobrachytherapy, the method of this project, simultaneously use of two processes of thermotherapy and brachytherapy is considered, which can be a more effective treatment for the destruction of tumor tissue. In thermotherapy, the temperature of the tissue is artificially raised to a temperature that leads to cell dysfunction resulting in cell death. In brachytherapy, the destruction of defective tissue is done by placing a source in the tissue. In the present project, we supposed to consider both mechanisms simultaneously for treatment at the same time. In this project, radioactive material 125I is used as a source of radiation emission for brachytherapy. In... 

nowadays Acoustic play an important role in the treatment of various diseases, especially cancer. in 2020 cancer has been the cause of death for more than 10 million patients. High intensity focused ultrasound is a non-invasive technique that used successfully to treat Malignant cancers like liver, pancreas and prostate. One of the major problems of using acoustic waves is the absorption of high frequency waves by the tissue before reaching the target area. in this study, a finite element model used to find the relation between frequency and acoustic pressure of transducer and focal region intensity. the results show, the maximum intensity in focal region linearly proportional to frequency... 

In this research, diffraction limit is introduced as the major challenge in wave focusing. Common wave focusing techniques have been reviewed and classified into two categories: far-field and near-field techniques. Through examples that illustrate its major inherent and practical challenges, super-oscillation has been presented as a specific idea of focusing waves using remote sources. By introducing subwavelength inhomogeneities in the region of interest, we have demonstrated sub-diffraction wave focusing in a near-field approach. Using the multipole method, the effect of injecting sub-wavelength cylindrical particles on focusing electromagnetic waves has been studied. Since when there are...