7.2.11

Ultrasound Imaging

Test yourself on Ultrasound Imaging

Test your knowledge with free interactive questions on Seneca — used by over 10 million students.

Acoustic Impedance and Attenuation

Reflection at a boundary between materials depends upon the difference in Z. The reflected intensity increases with increasing difference in acoustic impedance.

Acoustic impedance

Acoustic impedance

  • Acoustic impedance (more accurately specific acoustic impedance) of a material (Z) = density x velocity of sound in the material.
Comparative attenuation

Comparative attenuation

  • Bone has approximately 4x the impedance of muscle, and 10 000x the impedance of air.
  • Ultrasound will also be attenuated by the material it is propagating through.
  • The attenuation depends upon the frequency of the sound.

A and B Scans

There are two types of ultrasound scans:

A scans

A scans

  • A-scans are similar to traditional echo-sounding techniques.
    • Distances between layers in the body can be easily measured.
B scans

B scans

  • For a B-scan, the position and orientation of the transducer are used to provide an image of a section of the body.
    • The transducer is moved by the operator to provide information from these different positions.

Advantages and Disadvantages of Ultrasound

Ultrasound can be a very helpful medical imaging device however, it cannot be used effectively in all situations.

Advantages of ultrasound

Advantages of ultrasound

  • Ultrasound gives accurate information about the distance of layers of tissue from the time taken for reflection to happen.
  • Ultrasound is non-ionising so is safe for soft tissue.
  • Ultrasound can give information on the density of material from how intense the reflection is.
  • Ultrasound is safe for use on pregnant mothers.
Disadvantages of ultrasound

Disadvantages of ultrasound

  • The resolution is not as high as when an X-ray is used.
  • Due to the difference in acoustic impedance ultrasound will not produce an image from organs with large amounts of gas, like the lungs.
  • We are not aware of the long-term effects of ultrasound on soft tissue or on a fetus.
Jump to other topics
1

Physical Quantities & Units

2

Kinematics

3

Dynamics

4

Force, Density & Pressure

5

Work, Energy & Power

6

Deformation of Solids

7

Waves

8

Superposition

9

Thermal Physics

10

Communication

11

Electric Fields

12

Current Electricity

13

Magnetic Fields

14

Modern Physics

Practice questions on Ultrasound Imaging

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
Answer all questions on Ultrasound Imaging

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium