1, the nature of different: CT is a use of X-ray to imaging detection, while ultrasound is different, is the use of ultrasound in the body between the reflection, propagation to receive information, and then by the computer to do processing, and ultimately the formation of a 1 can be observed in the image.
2, the thickness of the fault is different: CT detects the detected images are cross-sectional display of the human body, according to the different settings of the machine, the thickness of the fault is not the same, but ultrasound is not, ultrasound can be placed through the probe position and the doctor's techniques, resulting in different angles of the section, can be observed in real time, repeated checks, is harmless to the human body.
3, the principle is different: according to the different tissues of the human body on the X-ray absorption and transmission rate of different, the application of extremely sensitive instrumentation on the human body to measure. ultrasound is not.
Expanded Information:
. p>Precautions:
1, in the ultrasound examination of the liver and gallbladder and other organs, should be fasting and water on the day of the examination. The dinner on the day before the examination should be light and less crumbly food, and on the morning of the examination day, breakfast and water should be forbidden to ensure that the examination is done in the morning on an empty stomach. If there is still a large amount of gas in the gastrointestinal tract after the prohibition of food and water, it will be necessary to take oral antiflatulent tablets 1-2 days before the examination to eliminate intestinal gas.
2, two days before the ultrasound, barium meal imaging of the gastrointestinal tract and cholangiography should be avoided. For patients who visit the doctor for digestive diseases, sometimes the doctor will prescribe barium meal fluoroscopy and ultrasound at the same time, the user is best to perform ultrasound first, and then barium meal imaging. Otherwise, misdiagnosis is likely to occur.
3, do the urinary system ultrasound and abdominal ultrasound, should be 1-2 hours before the examination, drink warm water 400-600 ml, to be bladder full before the examination.
Baidu Encyclopedia - CT
Baidu Encyclopedia - Ultrasound