B超是通过观察人体组织对超声波的不同反馈而观察组织、器官,由于空气对超声波是完全不反馈的,因此含气的脏器都不能用B超去观察,如肺、肠道。致密组织如头骨、胸骨等超声波很难通过,因此也不能用超声波观察,除以上部位外,其余大部分的人体组织和器官都可以用B超来观察。可用B超观察、诊断和随诊的肿瘤有:皮肤软组织肿瘤、甲状腺肿瘤、乳腺癌、肝胆肿瘤、胰腺肿瘤、肾脏肿瘤、输尿 B-ultrasound observes tissues and organs by observing different feedbacks from human tissue to ultrasound. Since air does not feedback ultrasonic waves at all, the organs containing gas cannot be observed with B ultrasound, such as the lungs and intestines. Ultrasound such as skull and sternum is difficult to pass through dense tissues such as skulls and sternums, so it cannot be observed by ultrasound. Except for the above parts, most of the other tissues and organs can be observed with ultrasound. The tumors that can be observed, diagnosed and followed by B ultrasound include: soft tissue tumors, thyroid tumors, breast cancers, hepatobiliary tumors, pancreatic tumors, renal tumors, and urinary tract