Specific Absorption Rate Investigation of Different EBG-M Applicator Structures for Non-invasive Hyperthermia Cancer Tre
The paper presents the results of an investigation of the effects of specific absorption rate (SAR) when applicators (antennas) are used in non-invasive hyperthermia cancer treatment procedure. Several different applicator structures were constructed and
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1 Faculty of Electrical Engineering, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia Faculty of Medicine and Health Sciences, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
Abstract— The paper presents the results of an investigation of the effects of specific absorption rate (SAR) when applicators (antennas) are used in non-invasive hyperthermia cancer treatment procedure. Several different applicator structures were constructed and the SAR simulation was observed. Rectangular and circular microstrip applicators were initially designed, and then an EBG and water bolus structure was integrated with the applicator. This applicator termed EBG-M applicator was constructed and its SAR simulation was observed using the SEMCAD X solver software. The results indicated that the EBG-M applicators provided better SAR distribution pattern, where the EBG-M with rectangular structures offered better focusing capability, which reduced the unwanted hot spots at the surrounding healthy tissues. Meanwhile, the EBG-M with circular structure obtained better penetration depth. In addition, when the water bolus is added to the structure, it resulted in shaping the SAR contour and provided a cooler environment which then reduced the skin burn problem during the treatment. Keywords— SAR, Non-invasive, Hyperthermia, Applicator, Penetration depth, Focusing
I. INTRODUCTION Hyperthermia is an alternative modality for cancer therapy. It provides treatment by using temperature, between 410C – 450C for a certain period of time. Denaturation of the treated cancerous tissue towards necrotic tissue can be accomplished with applied heat either by hyperthermia itself or as adjuvant with chemotherapy and radiotherapy in cancer treatments, since hyperthermia can increase the sensitivity to chemical drugs and radiation, respectively. Current technology for non-invasive hyperthermia is basically based on electromagnetic and ultrasound technique. Pros and cons are observed for both techniques. The electromagnetic technique, however, offers safer therapy towards the treated cancerous tissue, whereby ultrasound may result in bone heating injuries due to high heat absorption and penetration. On the other hand, there are deficiencies of using electromagnetic technique. This must be solved to enhance and increase the efficiency of non-invasive hyperthermia treatment when electromagnetic heat generation technique is
used. Despite tremendous research in recent years, major challenges such as lack in penetration depth, especially towards deep-seated cancerous tissue and also the absence of an appropriate applicator that will provide wellcontrolled temperatures, which will prevent the undesired hot spots from overheating and damaging healthy tissue in the surrounding cancerous region. One of the parameters that can be used to evaluate and measure the efficiency of a suitable applicator is to observe the heat distribution pattern and heat penetration that it provides through heat absorption into the treated cancerous tissue. This can be
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