scholarly journals Modeling of Interstitial Microwave Hyperthermia for Hepatic Tumors Using Floating Sleeve Antenna

Author(s):  
Faihaa Eltigani ◽  
Sulafa Ahmed ◽  
Maged Yahya ◽  
Mawahib Ahmed

Abstract PurposeMicrowave hyperthermia is a treatment modality that uses microwaves to destroy cancer cells by increasing their temperature to 41- 45°C. This study aims to design, modeling, and simulation of a microwave sleeve antenna for hepatic (liver) hyperthermia. MethodThe designed antenna resonated at 2.45 GHz. The antenna was tested in six different 3D liver models: Model A: without a tumor and blood vessels; Model B: with a realistic tumor (2x3 cm) and without blood vessels; Model C: created by adding blood vessels to model B; Model D: created by adding a small tumor (1.5x1.5 cm) to model C and changed its location; Model E: same as model C with a different tumor size; Model F: model with a simple spherical tumor (1.5x1.5 cm).ResultsThe return loss of the antenna varied from -45 dB to -25 dB for the 6 models. The Specific Absorption Rate (SAR) was between 29 W/kg to 30W/kg in the tumors and below 24 W/Kg in the surrounding tissues. The tumors’ temperature elevated to 43- 45°C, while the temperature of the surrounding tissues was below 41°C.ConclusionsThe results showed the capability of the designed antenna to raise the temperature of hepatic tumors to the therapeutic ranges of hyperthermia.

2021 ◽  
Author(s):  
Faihaa Eltigani ◽  
Sulafa Ahmed ◽  
Maged Yahya ◽  
Mawahib Ahmed

Abstract Background: Liver tumor, also known as hepatic tumor is one of the most common cancers with 80% of cases occurs in developing countries. Microwave hyperthermia is one of the promising treatment modalities that use microwaves to destroy the cancer cells by rising their temperature to 41- 45°C. This temperature elevation is achieved by using an applicator such as antennas. This study aims to design a microwave sleeve antenna capable of heating hepatic tumors (with different sizes and locations) to the therapeutic range of temperature for hyperthermia. Method: The sleeve antenna was designed to be resonate at 2.45 GHz and tested in a free space. Then; the antenna was tested in 6 different 3D liver models: Model A: without a tumor or blood vessels, Model B: with a tumor (2B3cm) and without blood vessels, Model C: created by adding blood vessels to model B, then a small tumor (1.5a1.5cm) was created and its location (Model D) and size (Model E) were changed. Finally, a model with a spherical tumor of 1.5 cm diameter (Model F) was tested. Results: The return loss (S-parameters) of the antenna was varied from -45 dB to -25 dB in the different liver models. The Specific Absorption Rate (SAR) reached 30W/kg in the tumor and less than 24 W/kg in the surrounding tissues, while the tumor temperature elevated to the therapeutic ranges of hyperthermia in the all models and the surrounding tissues remain at a safe temperature range. Conclusions: The obtained results showed the capability of the designed antenna to raise the temperature of hepatic tumors to the therapeutic ranges of hyperthermia.


Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3500
Author(s):  
Marija Radmilović-Radjenović ◽  
Martin Sabo ◽  
Marta Prnova ◽  
Lukaš Šoltes ◽  
Branislav Radjenović

Knowledge of the frequency dependence of the dielectric properties of the lung tissues and temperature profiles are essential characteristics associated with the effective performance of microwave ablation. In microwave ablation, the electromagnetic wave propagates into the biological tissue, resulting in energy absorption and providing the destruction of cancer cells without damaging the healthy tissue. As a consequence of the respiratory movement of the lungs, however, the accurate prediction of the microwave ablation zone has become an exceptionally demanding task. For that purpose, numerical modeling remains a primordial tool for carrying out a parametric study, evaluating the importance of the inherent phenomena, and leading to better optimization of the medical procedure. This paper reports on simulation studies on the effect of the breathing process on power dissipation, temperature distribution, the fraction of damage, and the specific absorption rate during microwave ablation. The simulation results obtained from the relative permittivity and conductivity for inflated and deflated lungs are compared with those obtained regardless of respiration. It is shown that differences in the dielectric properties of inflated and deflated lungs significantly affect the time evolution of the temperature and its maximum value, the time, the fraction of damage, and the specific absorption rate. The fraction of damage determined from the degree of tissue injury reveals that the microwave ablation zone is significantly larger under dynamic physical parameters. At the end of expiration, the ablation lesion area is more concentrated around the tip and slot of the antenna, and the backward heating effect is smaller. The diffuse increase in temperature should reach a certain level to destroy cancer cells without damaging the surrounding tissue. The obtained results can be used as a guideline for determining the optimal conditions to improve the overall success of microwave ablation.


Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Rongqiang Li ◽  
Bo Li ◽  
Guohong Du ◽  
Xiaofeng Sun ◽  
Haoran Sun

A compact broadband implantable patch antenna is designed for the field of biotelemetry and experimentally demonstrated using the Medical Device Radiocommunications Service (MedRadio) band (401–406 MHz). The proposed antenna can obtain a broad impedance bandwidth by exciting dual-resonant frequencies, and has a compact structure using bent metal radiating strips and a short strategy. The total volume of the proposed antenna, including substrate and superstrate, is about 479 mm3 (23 × 16.4 × 1.27 mm3). The measured bandwidth is 52 MHz (382–434 MHz) at a return loss of −10 dB. The resonance, radiation and specific absorption rate (SAR) performance of the antenna are examined and characterized.


2021 ◽  
Vol 17 (37) ◽  
pp. 211
Author(s):  
Mousume Samad ◽  
Mostafizur Rahman ◽  
S. M. Shamim

Continuous follow-up of unusual fibroids growth in the uterus is critical for minimizing the unwanted complexities of female’s certain health conditions. This article presents an implantable circular-shaped multi-facet PIFA for early detection of uterus fibroids. The radius of the circular antenna is 7.5 mm with the dimension of π × (7.5)2 × 1.58 mm3. The antenna has maximum return loss of 37 dB at 2.43 GHz, is suitable for ISM band use. Being low profile makes it entirely implantable in uterus. To expand the radiation efficiency and enhance the bandwidth two dielectric substrates of FR-4 and Rogers RO 3210 with each thickness of 0.79 mm are utilized. Top and bottom sides of the antenna have covered with Teflon to ensure biocompatibility. Defected ground structure has been used for size reduction as well as bandwidth increase. The performance of the antenna is also investigated in free space, biocompatible layer, and uterus layer. The estimated specific absorption rate is 0.36 W/kg when implanted in uterus.


2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Md Ikbal Hossain ◽  
Mohammad Rashed Iqbal Faruque ◽  
Mohammad Tariqul Islam

AbstractThis paper represents a comparative study on electromagnetic (EM) absorption in the human head between a printed monopole antenna and a planar inverted-F antenna (PIFA). The specific absorption rate (SAR) values and total absorbed power in the human head phantom are used to evaluate EM absorption for both antennae. Moreover, antenna performances in terms of return loss, radiation efficiency, and gain are also investigated in this study. The finite integration technique (FIT) based on CST Microwave studio and SAM head phantom are used in this study. The antenna performances are measured in an anechoic chamber and the SAR is tested using COMOSAR measurement system. The obtained results indicate that the printed monopole antenna lead to higher EM absorption in the human head as compared to PIFA for both GSM frequencies.


2015 ◽  
Vol E98.B (7) ◽  
pp. 1173-1181 ◽  
Author(s):  
Akihiro TATENO ◽  
Tomoaki NAGAOKA ◽  
Kazuyuki SAITO ◽  
Soichi WATANABE ◽  
Masaharu TAKAHASHI ◽  
...  

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