Ultrasound Flashcards
What is ultrasound?
A very high frequency sound waves that are pulsed into the body.
Returning echoes are analysed by a computer and displayed on the screen for interpretation.
Provides us with a cross-sectional image of organs, tissues, and blood action with tissues.
What are sound waves characterised by?
Wavelength, frequency, and amplitude.
What is the difference between high and low frequency?
High frequency
– better image quality, unable to penetrate further into the body.
Low frequency
– lower image quality, able to penetrate further into the body.
What are the advantages of ultrasound?
- Quick
- Non-invasive
- In practice machines
- Can scan any part of body
- Real-time picture
- No ionising radiation
- Differentiate soft tissues from fluid
- Patient doesn’t need sedation or anaesthetic.
- Easily repeatable
- Painless
What are the disadvantages of ultrasound?
- Can be expensive
- Inability to penetrate bone or air
- Difficult technique
- Limited sensitivity
- Interpretation relies on operators coordination and experience
What equipment is involved in ultrasounds?
Control pannel, gel, transducer (probe), and printer.
What is the control panel?
Change image quality.
Intensity of sound in transducer.
Adjusts amplification of the returning echoes.
What is a transducer?
Variety of applications depending on the region of interest.
All ultrasound machines use transducers, which contain piezoelectric elements referred to as arrays.
Two types:
- array transducers
- phased array transducers
What is an array transducer?
Crystal elements are arranged in a line along the surface of the transducer.
Wide superficial field of view. – rectangular!
Require a large contact area between the skin and transducer.
Uses:
Musculoskeletal system
Abdominal organs
Eyes
Body
What is a phased array transducer?
Contain a small number of crystals that are fixed in position and create a fan-type image.
Allows visualisation of deep structures due to a wide field of view.
Phased arrays have poor near-field image resolution.
Uses:
- Deeply located structures of the abdomen.
- Deeply located structures of the thoracic cavity.
What are the common uses for ultrasound?
Abdomen
Thoracic
Heart
Blood flow
Pregnancy
Muscles
Ligament/Tendons
Eyes
What type of ultrasound gel is used?
Water based gel that allows sound to pass through it easily.
Applied to the skin prior to ultrasonography to help in the transmission of soundwaves from the transducer to the patient’s skin, producing a clear image.
Eliminates air between skin and transducer.
How are ultrasound images produced?
- Sound waves are created by vibration of special crystals within the transducer/probe.
- The crystals shape is altered when an electrical current is applied
- Once the transducer is applied to the skin – soundwaves pass through soft tissues as pressure waves.
- At interfaces with tissues or different cells some soundwaves are reflected back to the transducer.
- The soundwaves vibrate the tissues and the crystals within the transducer.
- Soundwaves are then converted back to electrical Impulses.
- Electrical impulses are converted into an image via the computer.
- A cross-sectional image is produces which can show the internal architecture of the tissues.
Ultrasound image
What is anechoic?
Black areas
Ultrasound image
What is hypoechoic?
Dark areas
