Zusammenfassung der Ressource
Medical Imaging
- Radiography (xray
imaging)
- Best for broken bones, dentistry & some soft tissues.
- Photographic film and xray
Generator. Rays expose film and
turn it black.
- No rays reached paper = white
(bones and metal show up as
white)
- Xrays are ionising
and exposure has to
be kept to a
minimum.
- Xrays have contrasting agents that
can boost attenuation coefficient of
soft tissues - better distinguishing of
soft tissues - in the form of an artifical
contrast medium
- In the digestive system, barium is
given containing barium sulfate to
identify stomach/intestinal
blockages.
- relatively Cheap
- CAT Scanning - computer tomography
- Produces more detailed picture than
xray by putting the image together
using a computer.
- Consists of a rotating x-ray source and a ring of
detectors surrounding the patient. Data
produced builds up a detailed cross sectional
image
- CAT scan has 100X more ionising radiation
than xray to be built up into a 3D
image
- This means that the patient is limited
to the amount of CAT scans they can
have, and it also puts the
radiographer at risk.
- MRI scanning - magnetic
resonance imaging
- Carries no known risks
- Loud
- Not good for young
children/claustrophobes
- Some patients may need
sedation or restraint
- Ring-shaped
electromagnets that line
the MRI unit
- When switched on
protons in the body
(from hydrogen atoms)
line up in the
electromagnetic field
- once lined up a radio frequency is emitted which
disturbs proton alignment and causes them to rotate,
emitting tiny radio frequency signals.
- Expensive - maintenance of
machine and supply of helium to
be made into liquid helium to
keep the electromagnetic coil cold
is very costly.
- Small radio frequency coil is
used to cover relevant parts
of the body to pick up signals
from resonating protons,
which allows them to then be
converted into an image
- Not appropriate for
patients with metal
implants
- Term used to describe any
method used to view the inside of
the body without invasive surgery
- Ultra sound scanning
- Uses high frequency sound
emitted from a transceiver
unit, which rebounds off of
tissue
- Gel has to be used so that air gaps do not
disrupt the signal
- Cheap - only
needs one unit
- Means it is
accessible to
LEDCs.
- Real-time imaging
- Useful in prenatal scans as is can
detect deformities without invasive
testing which could be harmful to the
baby