Diagnostic Imaging
MEDICAL INTERVENTIONS
MRS. STEWART
CENTRAL MAGNET SCHOOL
X-Ray
 Noninvasive medical test used to produce images of the
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inside of the body to help diagnose medical conditions.
X-rays are a form of electromagnetic radiation that is sent
through the body.
Structures that are dense, such as bone, will block most of
the X-ray particles and appear white.
Metal and contrast media, a special dye used to highlight
areas of the body, will appear white.
Structures containing air will appear black and muscle,
fat, and fluid will appear gray.
X-Ray
 Produces two-dimensional
images.
 Examines bones, teeth,
lungs, breasts, heart, blood
vessels, and the digestive
tract.
 Uses ionizing radiation
which can increase risk of
developing cancer.
©iStockphoto.com
X-Ray – The Procedure
 X-ray is performed by a
machine that sends
individual X-ray
particles, called photons,
through the body.
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The photons pass through
the body and the resulting
images are recorded on a
computer or special film.
©iStockphoto.com
Advantages and Disadvantages
Advantages
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Quick, painless,
noninvasive test
Relatively inexpensive
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Cheaper than a CT or MRI
– cheapest test that takes
pictures of the body
Disadvantages
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Small amount of radiation
exposure
Contrast materials
sometimes used might
produce an allergic
reaction
CT Scan – Computerized Tomography
 Also called Computerized Axial Tomography (CAT
Scan).
 Noninvasive medical test used to produce images
of the inside of the body to help diagnose and treat
medical conditions.
 A series of X-ray views taken from many different
angles are combined to produce cross-sectional
images of the bones and soft tissues inside your
body.
CT Scan
 Produces cross-sectional
images of the body.
 Examines the chest,
abdomen, pelvis, spine,
and other skeletal
structures.
 Uses ionizing radiation
which can increase your
risk of developing cancer.
©iStockphoto.com
CT Scan – The Procedure
 CT scan is performed inside a
large tube that looks like a
large doughnut standing on
its side, and the person lies on
the table in the center.
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The X-ray tube rotates around
the body.
The table slowly moves through
the inside of the machine.
Each rotation yields several
images of thin slices of the
body.
©iStockphoto.com
Advantages and Disadvantages
Advantages
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Painless, noninvasive, and
accurate test that is fast
and simple
Able to image bone, soft
tissue, and blood vessels
all at the same time
Can be performed if
patient has an implanted
medical device of any kind
Disadvantages
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Small amount of ionizing
radiation exposure
Contrast materials
sometimes used might
produce an allergic
reaction
MRI – Magnetic Resonance Imaging
 Noninvasive medical test used to produce images
of the inside of the body to help diagnose and
treat medical conditions.
 Unlike X-rays and CT scans, which use radiation,
MRI uses powerful magnets and radio waves.
 Detailed images produced of soft tissue, (versus
X-rays and CT scans, which produce images of
hard tissues such as bones and teeth).
MRI
 Produces cross-sectional
images of the body.
 Used to examine the
brain, spine, joint,
abdomen, blood vessels,
and pelvis.
 Is very safe as the
magnetic field itself does
not hurt people (unless
they have certain types of
metal implanted in their
body).
MRI brain scan
MRI – The Procedure
 MRI scan is performed
inside a large magnet, and
the person lies on the table
in the center.
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The machine scans the body
by turning small magnets on
and off.
Radio waves are sent into the
body.
The machine then receives
returning radio waves and
uses a computer to create
pictures of the part of the
body being scanned.
©iStockphoto.com
Advantages and Disadvantages
Advantages
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Noninvasive test that poses
almost no risk when safety
guidelines are followed
Does not involve exposure to
ionizing radiation
Images of the soft tissue
structures of the body are more
likely to identify and accurately
characterize diseases than
other imaging methods
Contrast materials sometimes
used less likely to produce an
allergic reaction than those
used in x-rays and CT scans
Disadvantages
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Implanted medical devices
that contain metal may
malfunction or cause
problems during an MRI exam
Very slight risk of an allergic
reaction if contrast material is
injected
Confined space may induce
panic or feelings of
claustrophobia in some
patients
CT vs. MRI
 Both provide a cross-sectional
view creating a 3D image
 CT is faster and less expensive
 MRI provides a more detailed
view than a CT for soft tissue
Cross – section view
CT vs. MRI vs. XRay
 Xray is least expensive of the 3
 MRI is more expensive than a CT
 CT is safest to use on patients when medical
history is unknown
 CT is quicker than an MRI
 MRI provides a better/more detailed picture than
a CT
 Xray is 2D; CT and MRI provide 3D images
Bone Scan
 Noninvasive medical test used to produce images of
the bones that help diagnose and track several types
of bone disease.
 Bone scan is a nuclear imaging test.
Bone Scan
 Produces 2D images of the
entire skeleton.
 Used to detect abnormalities.
 Tiny amounts of radioactive
tracers (radionuclides) are
injected into the body
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These will be absorbed by bone
cells that are doing the most
growth and metabolism
These tracers will cause dark
spots on the scan where they
are absorbed most
Notice how the darkest areas are
those experiencing the most
growth in this adolescent – right
on the growth plates
©iStockphoto.com
Bone Scan Identifying a Tumor on Shoulder
Bone Scan – The Procedure
 An injection of tracers is administered to the
patient and allowed to circulate and be absorbed by
the bones.
 Once absorbed, the patient lies on a table while a
machine passes a gamma camera over the body to
record the pattern of tracer absorption by the
bones.
 Radiologists look for abnormal bone metabolism
on the scan, areas that show up as darker or lighter
where tracers have or have not accumulated.
Advantages and Disadvantages
Advantages
 Noninvasive
 Extremely
sensitive to
abnormalities and
variations in bone
metabolism
 Can scan the entire
skeleton
Disadvantages
 Cannot determine
cause of bone
metabolism
abnormalities
 Tracers
used produce
a small amount of
radiation exposure
PET Scan
 A positron emission
 A PET scan can reveal the
tomography (PET) scan is
an imaging test that uses a
radioactive substance
called a tracer to look for
disease in the body.
 A PET scan shows how
organs and tissues are
working.
 Sugar and radioactive
tracers are injected
together.
size, shape, position, and
some function of organs.
 This test can be used to:
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Check brain function
Diagnose cancer, heart
problems, and brain
disorders
See how far cancer has
spread
Show areas in which there is
poor blood flow to the heart
PET Scan
Application Questions
 A patient enters a hospital after hitting her head in a
car accident. She is diagnosed with a fractured skull
but has other symptoms that she is suffering from
brain damage. What technology should be used to
confirm this diagnosis?
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Does it make a difference if I tell you this patient has screws in
her left knee after a bad break as a kid?
Application Questions
 Design a patient situation where it would be
inappropriate to use an MRI scan as a diagnostic tool
Application Questions
 Evaluate the Dr’s reason for using a combination of
X-rays, CT scans, bone scans and MRI scans when
diagnosing Mike’s osteosarcoma (bone cancer).
Application Questions
 Why do you think patient’s are often fearful of
having an MRI or CT scan?
Application Questions
MRI
CT
Ultrasound