Transcript Radiology Part Deux

CT Scans (CAT Scans)
 CT scanning or (CAT
scanning) is using X-rays
to create a 3D image of
the inside of an object.
 CT stands for computed
tomography.
 Tomography is
developing an image in
sections or slices.
History
 Believe it or not, the first
slice of tissue
photographed on x-ray
film (tomography) was
done by Alessandro
Vallebona in the early
1900s.
History
 When computers developed
and technology advanced,
two men, the Brit, Godfrey
Hounsfield and the South
African Allan Cormack won
the Nobel Prize in Medicine
in 1979 for creating the first
CT scanner independently.
 The funding of the mass
production of these machines
was done by the same
company that produced
Beatles albums, EMI!
First scanner funded by EMI
CT Scan Usage
 CT scans are the “gold
standard” in the
diagnosis of a large
number of diseases.
 More recently they have
been used in
preventative medicine,
screening patients at
high risk before they
develop the condition.
Main Items CT Scans are used for
1.
Brain injuries, bleeding in the brain and skull
fractures.
Main Items CT Scans are used for
2. Brain tumors.
Main Items CT Scans are used for
3. Stroke patients and aneurysm patients in tracking
blood vessel leakage.
Main Items CT Scans are used for
4. Detection of airspace disease in the lungs (i.e.
emphysema).
Main Items CT Scans are used for
5. Tumors in the colon and other obstructive bowel
conditions.
Procedure for a CT Scan
Patient, depending on
the problematic area,
may need to ingest a
radioactive dye to better
show up the body regions
during the scan.
2. An X-ray rotates around
the body or body part
and takes pictures from
all angles.
3. The pictures are pieced
together on a computer
screen to give a 3D image
of the affected area.
1.
Cons against CT Scans
 The major knock against
CT scans is the cost.
 Other people argue about
the dosage of X-rays a
patient takes in from each
scan are too high.
 Lots of tests are not
conclusive, so other
imaging techniques or
exploratory surgery may
still be needed.
Magnetic Resonance Imaging (MRI)
 An MRI is used to image
the internal structures of
the body.
 It is done with much
better clarity than a CT
scan.
 It is useful in cancer
detection, joint injuries,
brain injuries and
cardiovascular problems.
MRI
 An MRI uses no
radiation, but instead
uses a power magnetic
field to align all the
hydrogen atoms in the
water molecules of the
body.
 Radio waves are then
used to create an image
based on the alignment
of the hydrogen atoms.
History
 MRI is a newer technology,
having first been used in
the early 1970s.
 They are now more
widespread, although they
are just as expensive to
build and maintain as CT
scans.
 Paul Lauterbur of the
University of Illinois, just
won a Nobel Prize in 2003
for his work on improving
MRIs.
MRI Procedure
 Very similar to a CT
scans, however no dye
needs to be ingested.
 The MRI machine passes
over the patient and uses
radio waves and a high
powered magnetic field
to create a 3D image.
MRI vs. CT Scans
MRI
CT Scans
 Expensive
 Expensive
 Better resolution at
 Better resolution at
distinguishing a contrast
between two similar looking
tissues.
 MRI can image in any plane.
 Due to the magnetic field,
certain problems can arise with
implants (pacemakers, metal
plates, hearing aids, etc…). No
radiation problems though.
determining individual
tissues.
 CT scans usually can only
image along the axial plane of
the body (from head to toe).
 No real problems with
implants, just the amount of
radiation.
PET Scans
 Positron emission
tomography is another
form of medical imaging.
 It is used for imaging
tumors, tracing blood
flow and looking at brain
activity to determine
brain disease/dementia.
How PET works
The patient is injected
with a radioactive
“tracer” molecule.
2. Wait until the tracer gets
incorporated into the
tissue in question.
3. Send the patient through
the PET scanner which
gets a picture from the
gamma ray radiation
given off by the tracer
molecules in the tissue.
1.
PET Info
 It was developed at
Massachusetts General
Hospital in the 1950s.
 It is rare to be used on its
own. Usually used to
confirm information given
by a CT scan or MRI.
 It uses radioisotopes,
which give off radiation, so
there is a risk of radiation
exposure.
Homework
1) Do you think the different radiology options are cost
feasible? Why or why not?
2) Rank CT Scans, MRIs and PET scans in terms of
safety. Why did you rank them as you did?
3) Compare CT scans, MRIs and PET scans in terms of
what they can best diagnose. Which technology do
you feel would be the best for the following:
Cracked skull
2) Bleeding in the brain
3) Alzheimer's detection
4) Torn elbow ligaments
1)