2001 Fiscal Year Final Research Report Summary
Optical Tomography Using Change of Ultrasonic Velocity by Light Absorption in Tissue
| Project/Area Number |
12555014
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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 |
Applied optics/Quantum optical engineering
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
HORINAKA Hiromichi Osaka Prefecture University, Department of Engineering, Professor, 工学研究科, 教授 (60137239)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUNAKA Toshiyuki Aloka Co. Ltd, Department Manager, 超音波プローブ開発部, 技術部長
WADA Kenji Osaka Prefecture University, Department of Engineering, Assistant Professor, 工学研究科, 講師 (40240543)
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| Project Period (FY) |
2000 – 2001
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| Keywords | optical computed tomography / acousto-optic effect / ultrasonic velocity / ultrasonic phase / metabolic information / tissue / scattering medium / diagnostics |
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| Research Abstract |
The optical CT is particulary expected to be applied to measurement of distribution of oxyhemoglobin in the brain and spatial diagnosis of tumors. However it is difficult to reconstruct the optical tomography because a biological tissue is highly scattering medium for light. A method using ultrasonic velocity change due to light absorption was proposed to realize practical optical computed tomography.
The experimental setup for detecting the ultrasonic phase shift caused by the optical absorption was constructed. Two transducers were placed face to face in a transparent acryl container as a transmitter and a receiver. When light illuminates the scattering medium containing absorption objects, the temperature of the absorption area increases and the phase of ultrasonic wave propagating the area shifts. The phase and the amplitude of the receiver output are measured using the RF lock-in amplifier. The difference between the ultrasonic phase under light illumination and that in the dark is determined and is stored in a personal computer. As the measured value is phase-shift integrated along the propagation path of ultrasonic wave, the ultrasonic wave must be scanned around the sample in order to reconstruct the optical tomography image.
The phase shift of ultrasonic wave was observed even in the medium with a scattering coefficient equivalent to that of the human brain when ultrasonic wave passed through absorption objects under light illumination. The optical image of the absorption region in a scattering medium was reconstructed from the projection data of ultrasonic phase shift due to light illumination. The shape of the absorption object hidden in the chicken meat was recognized by detecting the ultrasonic phase shift due to light illumination.
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