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| The Spectrum of Ultrasound Echo Signal from Ocular Tissue |
| School of Medical Instrument and Food, University of Shanghai for Science & Technology, Shanghai 200000, China |
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Abstract The spectral parameters of echo signals from eyes are critical for designing the receiving filter of the ophthalmological ultrasound device. It is inappropriate to estimate the echo spectra of the eyes with the averaged acoustic attenuation coefficient derived from soft tissues, because the ocular tissues are far from uniform. This paper studies the echo spectrum from human eyes 〖WTBX〗in vivo〖WTBZ〗. A 10 MHz ultrasonic transducer is used to scan the human eye and the result shows that the center frequencies of echo signal from eyeball are almost unchanged from the lens till retina, but decline rapidly with the depth about 3~5 mm behind the fundus from retina with the average slope about -0.16 MHz/mm. When the contributions of the probe and electronic elements are eliminated, the remaining spectrum of the posterior lens capsule is relatively flat which is similar to the feature of a plane reflector with high reflectivity, while the remaining spectrum of fundus present an ascending trend with the frequency, which is close to the characteristic expected for Rayleigh scatters.
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