数字超声扫描仪(also known as诊断超声检查orultrasonography) is a诊断成像technique based on the application ofultrasound。它用于查看内部身体结构，例如tendons，，，，肌肉，，，，joints, blood vessels, and internal organs. Its aim is often to find a source of a disease or to exclude anypathology。The practice of examiningpregnantwomen using ultrasound is called产科超声，，，，and is widely used.

超声issound waves和frequencieswhich are higher than those audible to humans (>20,000 Hz). Ultrasonic images, also known as sonograms, are made by sending pulses of ultrasound into组织用一个probe。的声音回声摆脱组织；不同的组织反映了不同程度的声音。这些回声记录并显示为运算符的图像。

Many different types of images can be formed using sonographic instruments. The most well-known type is a B-mode image, which displays the acoustic impedance of a two-dimensional cross-section of tissue. Other types of image can displayblood flow，，，，motion of tissue over time, the location of blood, the presence of specific molecules, the组织的刚度， 或者三维区域的解剖。

Compared to other prominent methods of medical imaging, ultrasound has several advantages. It provides images in real-time, it is portable and can be brought to the bedside, it is substantially lower in cost, and it does not use harmful电离辐射。超声检查的缺点包括其视野的各种限制，例如患者合作的需求，对体格的依赖，难度成像结构背后的难度骨and air, and the necessity of a skilled operator, usually a trained professional.