It is a method of examination that uses ultrasound to examine the internal state (morphology, dynamics, function) of a living body, and began to be used in medicine in earnest in the late 1980s. The wavelength of the ultrasound used is 1 to 10 MHz, with 3.5 to 5.0 MHz used for the abdomen and around 7.5 MHz for the body surface. The output is low at less than several tens of mW/cm2, and many devices generate ultrasound using around 200 piezoelectric elements (such as lead zirconate titanate) in the probe (contact). The emitted ultrasound propagates through liquids and solids, and is reflected at the boundary surface of the medium with different specific acoustic impedance. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
超音波を利用して生体内の状態(形態,動態,機能)を調べる検査法で,1980年代後半より,本格的に医療に使用されるようになった。使用される超音波の波長は1~10MHzで,腹部用には3.5~5.0MHz,体表面には7.5MHz程度を使用。出力は数十mW/cm2以下と低く,多くの装置はプローブ(接触子)に200個程度の圧電素子(ジルコン酸チタン酸鉛など)を用いて超音波を発生させている。放射された超音波は液体や個体を媒体として伝播し,媒体のもつ固有音響インピーダンスの異なる境界面で反射する。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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