Types of Ultrasound Scans

We will investigate two types of ultrasound scans.

A-Scan

This is a simple type of scan. A pulse of ultrasound is sent into the tissue and the echoes are detected to determine the depth of the structure.

The thickness of the bone can be calculated using Δt , which is the time it takes for the ultrasound to travel twice the distance of the bone. Since the speed of ultrasound in bone is known, the thickness of the bone can be determined using the formula

$t=frac{v times Delta t}{2}$

where $v$ is the speed of ultrasound in the medium.

A-scans are used for simple procedures such as measuring the thickness of bones.

B-Scan

This type of scan produces more detailed images than A-scan. A series of pulses are directed at the organ, and each reflected pulse is analysed to the depth and nature of the reflecting surface. The timing of the reflected pulse provides information to the depth of the surface while the intensity provides information to the type of reflecting surface.

In the above diagram, it can be seen that when the series of pulses are sent, a pattern of dots is obtained, which allows the computer to generate an image of the scanned organ.