| Project/Area Number |
12558105
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | NIIGATA UNIVERSITY |
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Principal Investigator |
MIYAKAWA Michio NIIGATA UNIVERSITY Faculty of Engineering, Professor, 工学部, 教授 (50239357)
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| Co-Investigator(Kenkyū-buntansha) |
ISHII Nozomu Faculty of Engineering, Associate Professor, 工学部, 助教授 (50232236)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥13,200,000 (Direct Cost: ¥13,200,000)
Fiscal Year 2002: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2001: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥7,200,000 (Direct Cost: ¥7,200,000)
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| Keywords | Microwave computed tomography / Tims domain measurement / Measurement of biological object / Non-invasive measurement / Attenuation- and phase-constant / Distribution / Caring / Time resolution / 超広帯域計測 / 時間信号処理 / 広帯域アンテナ / 損失媒質 / 広帯域計測 / 伝搬時間 |
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| Research Abstract |
1. Conclusions of the study : Feasibility of microwave imaging using measurement techniques in time domain has been investigated. Time domains measurement techniques are used in this study for discriminating the wave components that transmitted on the straight path between two antennas from the scattered- or reflected wave components. This is a similar technique to CP-MCT in which the straight path between two antennas is discriminated by use of the techniques in frequency domain measurement of a chirp radar.
The developed experimental system of Time Domain Microwave Computed Tomography (TD-MCT) that is consisted of a vector network analyzer and microwave scanner and measures S21 in the frequency range from 0.8 GHz to 4.2 GHz. Transmission time between two antennas can be time domain signal is determined by the reflected waves made by placing a metal plate in front of the antenna aperture. Accordingly, the signal which has a specific time interval corresponding to the straight path betw
… More
een two antennas can be excised from the observed signal to make projection data in frequency domain. This image reconstruction procedure is repeated at every 500 MHz in the frequency range from 1 GHz to 4 GHz. The major differences were observed in the signal to noise ratio and amount of unavoidable artifacts caused by interference among the diffracted- and transmitted-waves. In image reconstruction with 1 GHz bandwidth, the image reconstructed by use of the frequency components from 1 GHz to 2 GHz exhibits the most excellent quality. It is concluded that the CP-MCT that was designed at 1 GHz to 2 GHz has been properly designed. The estimated spatial resolution of TD-MCT shows the same value with that of CP-MCT.
2. Practical significance of time domain microwave computed tomography : Generally speaking, any scanners of microwave computed tomography have to make measurement in bolus saline solution by immersing the antennas and biological object for impedance matching between them. Saline solution shows similar permittivity values with biological tissues in the frequency range of microwave imaging. The advantages of time domain measurement are derived most effectively by increasing the bandwidth of the signal as much as possible. On the other hand, it is hard to increase the frequency of tomographic measurement because transmission loss is increased abruptly when frequency increases. It is also hard to realize the antenna with a very wide bandwidth, for example more than 3 GHz in saline solution. CP-MCT extracts straight path transmission components from transmitted waves in frequency domain and TD-MCT does the same thing in time domain. However, CP-MCT can do it by measuring very low frequency signal which is lower than 1 kHz or less. This is an easy task as compared to the measurement procedure in time domain. It is considered that the advantages of TD-MCT will be found when spectral information can be used effectively. Less
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