History Review Flashcards
What is sound?
A travelling vibration that is received by a receiver.
What is frequency?
Cycles per second
What is the frequency of infra sound and give an example of something that uses it.
0-20 Hertz
Whale calls
What is the frequency of audible sound and what is it?
20Hz - 20 kHz
Any sound we can hear.
What is the frequency of ultrasound and what is an example of something that uses it?
Above 20,000 Hertz
UT, remote controls, NDT
If something has a frequency of zero?
It has no sound
What frequency does DMS use and what is the intensity?
Low intensity, 1-30 Megahertz
What frequency does therapeutic ultrasound use and what is the intensity?
20kHz - 1 MHz, high intensity.
How does high intensity ultrasound effect tissue?
Heats it up.
What is the difference between high frequency and low frequency in ultrasound?
High frequencies cannot travel (the waves get weaker faster) but they give good resolution in pictures.
Low frequencies can travel (penetrate deep) but give a lower resolution (worse picture)
Ex. Car stereo, the bass (low frequency) can be heard a distance from the car but the treble cannot
Who discovered the piezoelectric effect?
The Currie brothers
What is the piezoelectric effect?
When pressure (an electrical current) is applied to crystals it causes a vibration (sound waves) to enter the body
What is the reverse piezoelectric effect?
The sound waves bounce off of structures in the body and reflect back into the transducer, these echoes are then converted into an image
Who was the first person to have the idea to use ultrasound inside the body and what was his background?
Tom Park
He worked in the military (sonar used for iceberg and submarine detection)
What is A-mode?
Amplitude ultrasound (graph mode) Represented on a graph when sound bounces off of structures.
Who was the first person to use an ultrasound for medical purposes? What was it and what mode was used?
Karl Dussik
A-mode scanning was used to see a brain tumour.
Who is George Ludwig?
Used A-mode to diagnose the presence of gallstones
Who were Hertz and Edler?
Used A-mode to demonstrate heart motion, this lead to the development of M-mode ultrasound.
What is M-mode? What are some examples of what it is used for?
Motion Modulation mode
- Used to measure baby’s heart rate
- Used in echo to watch movement of valves
Who is known as the “Father of Obstetrical Ultrasound”? Why?
Ian Donald
- He worked with Tom Parker and used ultrasound to identify a gestational sac
What are 3 major things Ian Donald did in his career?
1) Worked with Tom Parker and used UT to identify a gestational sac and thus was know as “The Father of OB UT”
2) Worked with Tom Brown and developed the first compound scanner
3) He developed the biparietal diameter measurement (BPD)
What is BPD?
Biparietal diameter measurement
The measurement used to estimate the age of baby
What is biometry?
Measurement of fetus
What is real time scanning?
Dynamic scanning
A single frame is created several times per second to give the appearance of movement.
Ex. Animation/cartoons
What is the most basic form of UT?
A-mode
Describe how A-mode works
A-mode is represented by a graph on an a oscilloscope (screen showing electrical impulses). The distance between the transducer and a structure determines where an echo is seen along the time axis (horizontal), a spike is produced according to the amplitude (strength) of the echo. Each spike on the graph corresponds to a reflector.
What is B-mode? How does it work?
Brightness Mode
Like A-mode but instead of spikes the intensity (amplitude) of the echo is displayed by various shades of dots. The brighter the dot, the stronger the echo. A line of sound (scan line) is reflected and represented by dots on a graph, many scan lines = a picture.
How do fluid and tissue show up in B-mode?
Fluid is black, organs/tissue show as different shades of grey
What is Bi-stable?
Compound/static B-mode Two shades (black or white), not moving. No tissue differientation
What is a Cathode ray tube?
Basically a T.V.
Catho= source of electrons hit a screen and create a glow.
What is gray scale?
A B-Mode image that has many shades of gray representing tissue differences and instead of using a Cathode Ray Tube, a scan converter is used (memory)
What is an advantage to using gray scale scanning?
You can view the entire abdomen, not just a section.
How does real time scanning work?
B-mode pictures are captured at a rate fast enough to mimic physiological imaging (speeding up images to create real time movement).
The probe is constantly listening and firing.
How does M-mode work?
If a series of B-mode dots are viewed over time a change can be seen. (Movement)
What is parenchyma?
Tissue
What is Doppler used for?
Using colour, Doppler shows the direction of blood flow and also the quality (weak or strong pressure)
What does 3D mean?
3 Dimentions
What is 4D?
The 4th dimention is time, watching movement in real time.
Why is yellow sepia tone used on 3D scans of babies?
3D scans of grey babies look dead.
What is static scanning?
After real time scanning was invented any scans that do not move were renamed static (static, B-scan and articulated arm scan all mean the same thing)
What is contact scanning?
Describes the transition between when patients were placed in water baths for scans to actually having the transducer touch the patients. (Sound travelled through water instead of touching patient with the probe).
