Ultrasound Flashcards
Ultrasound is a higher.lower frequency than we can here
Higher
How are ultrasounds produced?
Electrical systems can be made which produce electrical oscillations of any frequency.
These can easily be converted into mechanical vibrations to produce sound waves of a higher frequency than the upper limit of human hearing.
What is the range for human hearing?
20 - 20,000 Hz
What is partial reflection of ultrasounds?
When a wave passes from one medium to another, some of the wave is reflected off the boundary between the two media, and some is transmitted (refracted).
You can point a pulse of ultrasound at an object, and wherever there are [ … … ], some of the ultrasound gets reflected back.
boundaries between one substance and another
The time it takes for the reflections to reach a detector can be used to measure…
… how far away the boundary is.
How is ultrasound used in medicine? (4)
Investigating blood flow in organs
Diagnosing heart problems
Checking on fetal development
Breaking down Kidney stones
What are kidney stones, why are they bad?
They are hard masses that can block the urinary tract.
How does ultrasound break down kidney stones?
An ultrasound beam concentrates high-energy wave at the kidney stone and turns it into sand-like particles. These particles then pass out the body in the urine.
Why is breaking down of kidney stones by ultrasound a good method?
The patient doesn’t need surgery.
It’s relatively painless
How do prenatal scans work?
Some of the ultrasound wave is reflected back, when it meets a boundary between two different media, and detected. The exact timing and distribution of these echoes are processed by a computer to produce a video image of the fetus
What machine do you use to find boundaries?
Oscilloscope (the traces on it)
What is the formula to work out the distance between boundaries? What do the letters stand for, what are their units?
s = v * t s = distance (meters, m) v = speed (meters per second, m/s) t = time (seconds, s)
