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英文誌(2004-)

Journal of Medical Ultrasonics

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1982 - Vol.9

Vol.9 No.03

Original Article(原著)

(0231 - 0236)

超音波CTにおける屈折の影響とその補正法

Influence of Refraction on Ultrasonic CT and Its Correction

伊藤 貴司1, 崔 宗秀1, 河西 千廣1, 栗田 克己2, 中島 真人2, 油田 信一3

Takashi ITOH1, Jong-soo CHOI1, Chihiro KASAI1, Katsumi KURITA2, Masato NAKAJIMA2, Shin-ichi YUTA3

1アロカ株式会社, 2慶応義塾大学理工学部, 3筑波大学電子情報工学系

1Aloka Co., Ltd., 2Faculty of Science and Technology, Keio Univ., 3Institute of Information Sciences and Electronics, University of Tsukuba

キーワード : computed tomography, ultrasonic imaging, degradation, refraction, reflection

Image degradations on ultrasonic CT (Computed Tomography) were evaluated by experiment using agar gel phantoms and by computer simulation. The phantoms were made by mixing agar gel with graphite powder and saccharose which mainly control attenuation and velocity respectively. The experimental results showed that the attenuation constants at the centers of the phantoms are always underestimated and that the errors depend on the velocity difference between the media and not on their actual attenuation constants. From computer simulation, it was determined that the attenuation errors are due to refraction of ultrasound and that they can be reduced by measuring the maximum values in the received intensity distributions. Although this correction method is not completely accurate as reflection is not considered, it was proved to be practical from the results of experiments and computer simulation.