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19 Cards in this Set
- Front
- Back
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Ultrasound |
Longitudinal sound wave with a frequency of over 20,000Hz. |
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Uses of ultrasound |
Pregnancy scans Breaking down kidney Measuring speed of blood flow Diagnosing soft tissue problems |
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Pregnancy scan |
The ultrasound waves are reflected off the different tissue boundaries and the times and distributions of the echoes are processed by a computer to form an image on the screen. |
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Breaking down kidney stones
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Kidney stones-hard masses which may block the urinary tract. An ultrasound beam concentrates high energy waves at the stone to break it down, using vibrations, into sand like particles which can be passed in urine. It's relatively painless and non-invasive. |
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Measuring the speed of blood flow. (Doppler ultrasound) |
A probe emits ultrasound waves into the body and if the blood is moving towards us waves squash up. The wavelength also shows the rate of blood flow. |
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CT scan |
Specialised X-Ray which combines multiple 2D images in order to construct a 3D image. Good for viewing oft tissue and has the dangers of X-Rays but in higher doses. |
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Thermionic emmission |
A negatively charged wire filament (cathode) is heated above 1,000 degrees c. This means electrons have enough energy to escape.They're accelerated to a spinning anode by a high voltage in a vacuum. When the electron beam hits the anode, some of the kinetic energy is converted into X-Rays. |
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Why is a vacuum used? |
If there was no vacuum, the electrons would collide with particles in the air and not reach the anode. |
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Uses of thermionic emmission |
Cathode ray oscilloscope (CRO) TVs To produce X-Rays |
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Factors which effect the strength of X-Rays |
Distance from the source to the target. Thickness of the material the X-Ray has to pass through. |
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Endoscopes |
A thin tube containing two tubes of optical fibres.One carries light from a lamp to the area of interest, whilst the other carries an image back so it can be viewed using the reflected light.The image can be seen through an eye piece or displayed as a full-colour moving image on a screen. It uses TIR. |
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Electrocardiograms (ECGs)
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When the heart beats, an action potential passes through the atria making them contract. Then the same occurs with the ventricles. The action potential produces a weak electrical signal on the skin which is recorded by an ECG using electrodes. The results are shown on a screen and allow heart rate to be monitored.
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Positron emission tomography (PET scans)
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A flat bed with large circular scanner at one end. You're injected with a radiotracer which gives out positrons that release gamma rays which the scanner detects. Tracking the tracer's movements builds up images and different concentrations of positrons show up in different colours/brightnesses. 3D images that show parts of the body and how effectively they're working
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Uses of PET scanners
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Diagnosing cancers
Work out est ways of treating cancers How well the body is responding to cancer cure Plan complex heart surgery Diagnose brain conditions |
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Fluorodeoxyglucose
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A radiotracer which the body treats like glucose. Studying how the body responds to glucose gives us information (this may show cancerous tissue as it processes glucose differently).
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How are the gamma rays produced?
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When a positron meets with an electron, the result is annihilation. All the mass is converted into energy (gamma rays). They collide at the same speed, head on and moving in opposite directions. 2 gamma rays are produced as momentum is conserved, so there must be a positive and negative momentum.
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Pacemaker
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A small electronic device inserted under the skin by the left shoulder. It contains a mini computer which processes electrical signals in the heart and sends out its own telling the heart to beat. Leads pass into the heart through a vein and pass the generated signals to the heart making the muscle contract and the heart beat regularly.
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Pulse oximetry
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A device is attached to your ear or finger which emits red light and has a photo detector to measure light. The light passes through tissue ad some is absorbed by blood, reducing the amount of light detected. The amount of light absorbed depends on blood colour.This tells you blood oxygen saturation.The amount absorbed fluctuates in response to heart beat so you can also monitor this.
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How does blood colour change?
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Haemoglobin's colour changes depending on its oxygen content. When it's rich in oxygen, it's bright red and after it has given away its oxygen, it's purple in colour.
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