The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of ...The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station.The paper investigates the electromagnetic wave absorption inside a human body.The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna(BSA)has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance(R)of human body from BSA is varied in the range of 0.1 m to 5.0 m.For the number of carrier frequency equal to one and R=0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies.Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.展开更多
Objective: To investigate the electromagnetic field and specific absorptionrate (SAR) distribution of different structure applicators with different depths for treating bonetumors using microwave hyperthermia. Methods...Objective: To investigate the electromagnetic field and specific absorptionrate (SAR) distribution of different structure applicators with different depths for treating bonetumors using microwave hyperthermia. Methods: The finite element method (FEM) was used to calculate,electromagnetic field and SAR distribution. Two different structure applicators were simulated. Theone is simple coaxial antenna, which has been successfully used in clinic treating bone tumors inTangdu hospital of the Forth Military Medical University several years. It was formed by a coaxialcable peeled off the out copper at end. The other applicator was coaxial- slot antenna, which waswidely used in microwave hyperthermia. The applicator inserted into the cylindrical bone withdifferent depths, and worked at the frequency of 2 450 MHz. Results: The electric field and SARgenerated by the simple coaxial applicator were mainly concentrated out the tissues, and were notuniform in the tissues, while the coaxial- slot applicator well transmits the electric field and SARinto the tissues, and can easily treat different position by adjusting the slat position.Conclusion: The results calculated by EFM, were well accordant with the experimental and clinicalresulls, and will be important for improving the clinical effects of microwave hyperthermia.展开更多
Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues...Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.展开更多
The impact of the electromagnetic waves (EM) on human neurons (HN) has been under investigation for decades, in efforts to understand the impact of cell phones (radiation) on human health, or radiation absorption by H...The impact of the electromagnetic waves (EM) on human neurons (HN) has been under investigation for decades, in efforts to understand the impact of cell phones (radiation) on human health, or radiation absorption by HN for medical diagnosis and treatment. Research issues including the wave frequency, power intensity, reflections and scattering, and penetration depths are of important considerations to be incorporated into the research study. In this study, computer simulation for the EM exposure to HN was studied for the purpose of determining the upper limits of the electric and magnetic field intensities, power consumption, reflections and transmissions, and the change in temperature resulting from the power absorption by human neurons. Both high frequency structural simulators (HFSS) from ANSYS software, and COMSOL multi-physics were used for the simulation of the EM transmissions and reflections, and the temperature profile within the cells, respectively. For the temperature profile estimation, the study considers an electrical source of 0.5 watt input power, 64 MHz. The EM simulation was looking into the uniformity of the fields within the sample cells. The size of the waveguide was set to be appropriate for a small animal model to be conducted in the future. The incident power was fully transmitted throughout the waveguide, and less than 1% reflections were observed from the simulation. The minimum reflected power near the sample under investigation was found to be with negligible reflected field strengths. The temperature profile resulting from the COMSOL simulation was found to be near 0.25 m°K, indicating no change in temperature on the neuro cells under the EM exposure. The paper details the simulation results for the EM response determined by HFSS, and temperature profile simulated by COMSOL.展开更多
The problems of EM energy absorption of human body irradiated by plane wave arediscussed by the Finite-Difference Time-Domain(FD-TD)method.The local Specific AbsorptionRates(SARs),the whole-body average SARs and the l...The problems of EM energy absorption of human body irradiated by plane wave arediscussed by the Finite-Difference Time-Domain(FD-TD)method.The local Specific AbsorptionRates(SARs),the whole-body average SARs and the layer average SARs for the inhomogeneousblock model of human body with different incident direction and different polarization of theincident waves are calculated.The results show that the appearance of maximum EM energyabsorption is not always at the situation of the front incidence and the local SARs are moreimportant for the interaction of the EM fields with human body.All results provide more infor-mation about the electromagnetic dosimetry for human body.展开更多
目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF...目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF、B0、体重和TR的函数。根据体重与10秒SAR的关系曲线,通过MATLAB,进行一个曲线拟合,得出10 s SAR与体重的关系方程式:SAR=((-5.96E-09)X4-(2.08E-06)X3+0.0005681X2-0.04531X+1.638)*Peak_SAR.结论SAR是RF脉冲序列、B0、体重和TR的函数,我们所得到的MATLAB4次方程式,只要输入病人体重和Peak_SAR就能直接得到10 s SAR,就可以估计扫描是否暂停,以及暂停时间。展开更多
CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their st...CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their structural and optical properties using X-ray powder diffraction(XRD)patterns,Fourier transform infrared spectroscopy,Raman spectroscopy,UV–Visible and photoluminescence studies.Morphological and compositional studies were carried out using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy,while the magnetic properties were determined using alternating gradient magnetometer and Mossbauer to define the magneto-structural effects of shell formation on the core NPs.Induction heating properties of CoFe2O4 and CoFe2O4@Au CS magnetic nanoparticles(MNPs)have been investigated and correlated with magneto-structural properties.Specific absorption rate and intrinsic loss power were calculated for these MNPs within the human tolerable range of frequency and amplitude,suggesting their potential in magnetic fluid hyperthermia therapy for possible cancer treatment.展开更多
In recent years, hyperthermia holds much attraction in the clinic practices, especially in the tumor treatment. In hyperthermia, the key to get much better therapeutic effects ts how to heat the tumor efficiently, tha...In recent years, hyperthermia holds much attraction in the clinic practices, especially in the tumor treatment. In hyperthermia, the key to get much better therapeutic effects ts how to heat the tumor efficiently, that means how to keep the tumor in high temperature range (41—45℃), and avoid any damage of the surrounding normal tissues. Therefore, the first requirement for hyperthermic system is to produce an ideal heating field of which the main part can overcover the region for therapy.展开更多
SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio P...SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio Power总辐射功率)这一相互制约的关系成了目前移动终端在保证高要求的发射功率条件下有低SAR值的难题。一般的降SAR方式为在主板上的热点处贴吸波材料,但是这有碍于终端的结构设计,并且成本较高,可靠性不佳。本论文通过天线本体设计来改变移动终端的主板上的电流分布,在保证总电流强度不减小的情况下通过降低主板上的电流峰值来降低SAR值。大大节省了降SAR成本。具有较高的推广性和可实现性。展开更多
基金This work is collaborative research with the Department of Electronics&Communication Engineering,Acharya Institute of Technology,Bengaluru,India.And also this work is a collaborative research between Yangon Technological University and University of Oulu in Finland based on the enhancement of Telecommunication Engineering Education in YTU.This work is fully supported by the government research funds of 2020-2021 academic year which is the grant no of GB/D(4)2020/4.
文摘The system analysis of specific absorption rate(SAR)in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works.The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station.The paper investigates the electromagnetic wave absorption inside a human body.The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna(BSA)has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance(R)of human body from BSA is varied in the range of 0.1 m to 5.0 m.For the number of carrier frequency equal to one and R=0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies.Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.
文摘Objective: To investigate the electromagnetic field and specific absorptionrate (SAR) distribution of different structure applicators with different depths for treating bonetumors using microwave hyperthermia. Methods: The finite element method (FEM) was used to calculate,electromagnetic field and SAR distribution. Two different structure applicators were simulated. Theone is simple coaxial antenna, which has been successfully used in clinic treating bone tumors inTangdu hospital of the Forth Military Medical University several years. It was formed by a coaxialcable peeled off the out copper at end. The other applicator was coaxial- slot antenna, which waswidely used in microwave hyperthermia. The applicator inserted into the cylindrical bone withdifferent depths, and worked at the frequency of 2 450 MHz. Results: The electric field and SARgenerated by the simple coaxial applicator were mainly concentrated out the tissues, and were notuniform in the tissues, while the coaxial- slot applicator well transmits the electric field and SARinto the tissues, and can easily treat different position by adjusting the slat position.Conclusion: The results calculated by EFM, were well accordant with the experimental and clinicalresulls, and will be important for improving the clinical effects of microwave hyperthermia.
基金This study was supported by the National Natural Science Foundation of China(Nos.62022037,61775028,81571722,61528401 and 61921002)Guangdong province(2019ZT08Y191)+1 种基金Shenzhen Science and Technology Program(KQTD20190929172743294)Startup grant from Southern University of Science and Technology.
文摘Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.
文摘The impact of the electromagnetic waves (EM) on human neurons (HN) has been under investigation for decades, in efforts to understand the impact of cell phones (radiation) on human health, or radiation absorption by HN for medical diagnosis and treatment. Research issues including the wave frequency, power intensity, reflections and scattering, and penetration depths are of important considerations to be incorporated into the research study. In this study, computer simulation for the EM exposure to HN was studied for the purpose of determining the upper limits of the electric and magnetic field intensities, power consumption, reflections and transmissions, and the change in temperature resulting from the power absorption by human neurons. Both high frequency structural simulators (HFSS) from ANSYS software, and COMSOL multi-physics were used for the simulation of the EM transmissions and reflections, and the temperature profile within the cells, respectively. For the temperature profile estimation, the study considers an electrical source of 0.5 watt input power, 64 MHz. The EM simulation was looking into the uniformity of the fields within the sample cells. The size of the waveguide was set to be appropriate for a small animal model to be conducted in the future. The incident power was fully transmitted throughout the waveguide, and less than 1% reflections were observed from the simulation. The minimum reflected power near the sample under investigation was found to be with negligible reflected field strengths. The temperature profile resulting from the COMSOL simulation was found to be near 0.25 m°K, indicating no change in temperature on the neuro cells under the EM exposure. The paper details the simulation results for the EM response determined by HFSS, and temperature profile simulated by COMSOL.
文摘The problems of EM energy absorption of human body irradiated by plane wave arediscussed by the Finite-Difference Time-Domain(FD-TD)method.The local Specific AbsorptionRates(SARs),the whole-body average SARs and the layer average SARs for the inhomogeneousblock model of human body with different incident direction and different polarization of theincident waves are calculated.The results show that the appearance of maximum EM energyabsorption is not always at the situation of the front incidence and the local SARs are moreimportant for the interaction of the EM fields with human body.All results provide more infor-mation about the electromagnetic dosimetry for human body.
文摘目的通过对SAR影响参数研究,计算10秒SAR,指导MR扫描顺利进行。方法采用GE公司HD3T扫描仪,头颅8通道线圈,扫描序列为T2-FSE,改变体重、TR、层数等参数对水模进行扫描,观察SAR的改变。结果SAR与体重和TR有关,而与扫描的层数无关,SAR是RF、B0、体重和TR的函数。根据体重与10秒SAR的关系曲线,通过MATLAB,进行一个曲线拟合,得出10 s SAR与体重的关系方程式:SAR=((-5.96E-09)X4-(2.08E-06)X3+0.0005681X2-0.04531X+1.638)*Peak_SAR.结论SAR是RF脉冲序列、B0、体重和TR的函数,我们所得到的MATLAB4次方程式,只要输入病人体重和Peak_SAR就能直接得到10 s SAR,就可以估计扫描是否暂停,以及暂停时间。
基金Author (Sandip Sabale) is thankful to University Grants Commission, New Delhi, India, for Raman Fellowship to work in USA (F. No. 5-105/2016 (IC), February 10, 2016
文摘CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their structural and optical properties using X-ray powder diffraction(XRD)patterns,Fourier transform infrared spectroscopy,Raman spectroscopy,UV–Visible and photoluminescence studies.Morphological and compositional studies were carried out using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy,while the magnetic properties were determined using alternating gradient magnetometer and Mossbauer to define the magneto-structural effects of shell formation on the core NPs.Induction heating properties of CoFe2O4 and CoFe2O4@Au CS magnetic nanoparticles(MNPs)have been investigated and correlated with magneto-structural properties.Specific absorption rate and intrinsic loss power were calculated for these MNPs within the human tolerable range of frequency and amplitude,suggesting their potential in magnetic fluid hyperthermia therapy for possible cancer treatment.
基金Project supported by the National Natural Science Foundation of China.
文摘In recent years, hyperthermia holds much attraction in the clinic practices, especially in the tumor treatment. In hyperthermia, the key to get much better therapeutic effects ts how to heat the tumor efficiently, that means how to keep the tumor in high temperature range (41—45℃), and avoid any damage of the surrounding normal tissues. Therefore, the first requirement for hyperthermic system is to produce an ideal heating field of which the main part can overcover the region for therapy.
文摘SAR(Specific Absorption Rate)通常称为吸收比值或吸收比率,是指移动终端电磁波能量吸收比值。目前国际通用的标准有两个,一个是欧洲标准(CE)每10克小于2.0w/kg,一个是美国标准(FCC)每克小于1.6mw/g。移动终端的SAR与TRP(Total Radio Power总辐射功率)这一相互制约的关系成了目前移动终端在保证高要求的发射功率条件下有低SAR值的难题。一般的降SAR方式为在主板上的热点处贴吸波材料,但是这有碍于终端的结构设计,并且成本较高,可靠性不佳。本论文通过天线本体设计来改变移动终端的主板上的电流分布,在保证总电流强度不减小的情况下通过降低主板上的电流峰值来降低SAR值。大大节省了降SAR成本。具有较高的推广性和可实现性。
