ultrasound is sound with a much higher frequency than we can hear.
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electrical oscillations
electrical systems can be made to produce electrical oscillations of any frequency. easily converted into mechanical vibrationsto produce sound waves of a higher frequency than the upper limit of human hearing. this is called ultrasound
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human range
20-20000 Hz
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waves
ultrasound waves get partially reflected at a boundry between media.
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Partial reflection
when waves pass from one medium to another some wave is reflected ooff the boundry of some media and some is transmitted and refracted. this is partial reflection.
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detecter
time it takes for the reflections to reach the detecter can be used to measure how far away the boundry is. this is how ultrasound imaging works.
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oscilloscope
you can use oscillope traces to find boundies.
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s=v*t
speed= velocity*time if you know the speed of sound in the medium you can work out the distance travelled.
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formaula
when working out formula remember if ultrasound reflected time result by 2. 1us=0.000001s
kidney stones are hard masses that can block urinary tract. ultrasound beam concentrates high energy waves at kidney stone and turns it into sand like particles. particles pass out of body like urine.patient does not need surgeory and it is painless.
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pre natal scanning
ultrasound waves can pass through body but when they meet a boundry between two diffrent media some of the waves are reflected back and detected. the exact timing and distribution of these echos are prossed by computer to produce video image.
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compromisis.
docters make compromisis between getting a good enough image to be able to diagnose problem whilst putting patient at low risk of disadvantages.
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safe
ultrasound waves are not ionising, x-rays are ionisingcan cause cancer if high dose, not safe for developing babies. ct scans use alot of radiation compared with xrays only used if really nessary.
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image quality
ultrasound images are fuzzy make it hard to diagnose illnessess.x rays produce clear image of bones and metal. ct scans produce detailed image can diagnose complicated images high resolution images can create 3d images.
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Other cards in this set
Card 2
Front
electrical systems can be made to produce electrical oscillations of any frequency. easily converted into mechanical vibrationsto produce sound waves of a higher frequency than the upper limit of human hearing. this is called ultrasound
Back
electrical oscillations
Card 3
Front
20-20000 Hz
Back
Card 4
Front
ultrasound waves get partially reflected at a boundry between media.
Back
Card 5
Front
when waves pass from one medium to another some wave is reflected ooff the boundry of some media and some is transmitted and refracted. this is partial reflection.
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