An ultrasound scan is a medical device that utilizes high frequency sound waves to create an imagine (sonogram) of the inside of the human body, such as blood vessels, muscle, joints, the stomach, liver, tendons, or the heart.
Many believe that ultrasound is safer than other forms of imaging because it uses sound waves rather than radiation.
Apart from helping detect problems in certain parts of the body, ultrasonography can also help guide surgeons when they carry out biopsies.
Higher sound frequencies produce better images but cannot penetrate as deeply as lower frequencies.
Ultrasound travels through fluids and soft tissues and bounces off denser surfaces. For example, when looking at the heart and blood vessels around it, ultrasound will travel through the blood, and bounce back off the heart valve.
The data of ultrasound bouncing back is processed in a computer, which then creates image on a monitor. If the doctor is viewing the gallbladder and there are no gallstone, the ultrasound with travel straight through, but will bounce back when there are stones.
The denser an object is, the harder the ultrasound bounces back. This echo (bouncing back) is what gives the ultrasound images their features – they can be seen on the screen as varying shades of gray.
Anesthetists sometimes use ultrasound for guidance when injecting anesthetics near nerves. Cardiac ultrasound refers to the creation of 2-D images of the heart. Some more modern machines can produce 3-D images.
Ultrasound can also be used to see how fast blood flows, or the state of cardiac tissue at specific points, by using pulses or continuous wave Doppler ultrasound.