Download Medical Imaging

Sumir Chawla
 Medical imaging is a technique used to create
images of the human body in order to reveal,
examine and diagnose disease.
 In its clinical sense it is carried out by
radiologists.
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 This is the oldest and most commonly used form of
medical imaging.
 X-rays use ionising (high-energy) radiation, which are
emitted from the X-ray tube, and are directed by the
lead shielding to a specific part of the body.
 As the X-rays passes through the body, the photons are
absorbed at different rates so that denser parts (bones)
absorb more than softer material (heart).
 There is a photographic plate below the body, which
capture a snapshot of the image, and is directly
connected to a computer.
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 The ionising radiation can theoretically cause
mutations in DNA.
 However the doses are very low and similar to levels of
background radiation.
 Lead shields are used to prevent unnecessary exposure
to radiation.
 For pregnant women, X-rays that directly target the
womb are not recommended.
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 The CT scanner is a large circular machine, which
contains an X-ray scanner that rotates around and uses
a series of X-ray beams to produce a detailed
tomogram (image).
 Since there are more beams of radiation, the images
are more detailed.
 The bed is motorised and you will be moved in and
out.
 You many be given a contrast medium, either orally or
injected, in order to improve the images of certain
vessels and tissues.
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 The patient lies inside a large cylindrical magnet.
 The body is largely made up of water, and at the nucleus of
a hydrogen atom is a proton.
 The radio waves affect the body’s atoms, forcing the
protons to move in a certain way. When they move back,
they transmit a radio signal which can be detected.
 Therefore tissues which have the most hydrogen atoms
(fatty tissue) look much brighter than those that have
fewer ( bones).
 The MRI produces detailed picture by changing changing
the timing of the radiowave pulses.
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Britain has fewer high-tech medical machines than
Estonia and Turkey
http://www.telegraph.co.uk/health/healthnews/8413647/
Britain-has-fewer-high-tech-medical-machines-thanEstonia-and-Turkey.html
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 Ultrasound is simply a procedure that creates images
using high frequency sound waves, which are directed
at a part of the body using transducers.
 When the sound waves hit an object, it will bounce
back as an echo and is recorded on the computer as an
image.
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Angiography
Angiography
 It is a type of X-ray, where a special dye (contrast
medium) is injected into to the body in order to allow
better examination of blood vessels, since they do not
show up clearly on normal X-rays.
 The patient is numbed by local anaesthetic, and then
the catheter is inserted into a blood vessel , usually on
the leg.
 Using the catheter the surgeon will inject the dye
which shows up on the angiograms as the blood is
pumped around .
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