Ultrasound Flashcards
What is an ultrasound wave?
A wave that has a frequency beyond the upper limit of human hearing
What is the limit of human hearing?
20-20000Hz
How do Ultrasounds work?
When a wave passes from one thing to another some of the wave is reflected off the boundary and some is transmitted (and refracted) this is partial reflection creating pulses
The timing and distribution of these echoes are processed by a computer creating a video image
How can we use oscilloscope traces to find boundaries?
work out the time between the pulses
How can you work out distance between boundaries?
S=v x t
How are ultrasounds used to breakdown kidney stones?
They are hard masses that block the urinary tract an ultrasound beam concentrated high energy beams at the kidney stone and turns it in to sand like particles which the patient urinates out
How is a ultrasound used for prenatal scans?
Ultrasound waves pass through the body but when they meet a boundary some of the wave is reflected back and detected
The timing and distribution of these echoes are processed by a computer creating a video image
What is an advantages of ultrasound waves?
They are non-ionising and safe
What is a disadvantage of ultrasound waves?
The image is typically fuzzy which makes some conditions hard to diagnose
How do you measure how far away the boundary is?
The time it takes for reflections to reach detector
What are the features of x rays?
Electromagnetic waves High frequency High energy Short wavelength Very ionising
What are the features of an ultrasound wave?
20,000 Hz (beyond the upper limit of human hearing)
Longitudinal waves
Partially reflected at the boundary
Travel at different speeds in different mediums
