Transcript Imaging Highlights

Imaging Highlights
Imaging Techniques
• Used to visualize and examine internal
body structures
The three most common:
1.Radiography (x-ray)
2.Computed Tomography (CT)
3.Magnetic resonance imaging (MRI)
X-ray
• Many imaging techniques use x-ray which
is invisible, odorless, and can’t be felt.
• Used to radiate cancer- yet overexposure
can cause death.
• (See x-ray PP Google docs)
X-ray
• Image of hard-tissue. Internal structures created
by the exposure of sensitized film to x-radiation.
Resulting film known as an x-ray or radiograph
• Radiograph made up of shades of gray
• Radiopaque hard tissues, such as bone and
tooth enamel, do not permit x-rays to pass
through and appear white or light gray on
radiograph
• Radiolucent air and soft tissues do permit x-rays
to pass through, and appear as shades of gray
to black on the radiograph
Positioning
• Describes the body placement and the
part of the body closest to the film.
• Example: left lateral position, the left side
of the body is placed nearest the film
• http://www.rtstudents.com/radiologypositions.htm
• Hand out
PROJECTION
• Refers to the path the
beam takes through part
Anteroposterior projection
(AP)
• Beam enters the front surface
and exits the back surface of
the part
Posteroanterior projection
(PA)
• Beam enters the back and exits
the front of the part
AP projection in supine
position
PA projection in prone position
Lateral Projections
• Normally the
positioning terminology
is used rather than
projection
– torso and head
• Right to left lateral projection
• Left to right lateral projection
– extremities
• Mediolateral projection
• Lateromedial projection
L lateral erect position
R to L lateral projection
Oblique Projections
• Normally the
positioning
terminology is used
– example
RPO position = right
anterior to right
posterior projection
(oblique AP)
Radiographpy vs Nuclear
Medicine
Radiography – source of radiation is
external. Gamma rays pass through
body and form radiograph
Nuclear Medicine – source of
radiation is radiopharmaceutical
taken internally. X-rays pass out of
body and form scan image.
Ionization
• Ability of x-rays to
change substances
thru which they
pass
• Used to make
radiographs and
treat cancer
• May cause cell
damage and even
death
Nuclear Scan
• Radioactive
isotope tagged to
substance
absorbed by
specific tissue and
injected into the
blood
• Shows gross fx of
organ
• Good for images of
tumors or lesions
Common Scans
• Bone – fractures, tumors,
inflammation, bone growth
• Brain – tumors, blood flow
• Liver – cirrhosis, hepatitis, tumors,
cysts, abscesses
• Lung – blood clots, tumors
• Thyroid – function, tumors
• heart
Radioimmunoassay
• Mix blood with
radioactive
substance to
determine specific
blood protein
concentrations
• Find antibodies
and antigens
(titers)
Radiation Therapy
• Treatment of CA
with external
radiation
• Stereotactic –
focusing multiple
beams at the
same spot
Teletherapy vs Bradytherapy
Teletherapy –
radiation
source is
external
Bradytherapy –
radiation source
is internal
Tomography
• Imaging method
that produces
tomes (cross
sections) of body
along any plane
• Shows structure
• Good for images of
tumors- especially
when contrast
medium used
Mammography
• X-ray examination
of the internal
breast tissue
• Helps in
diagnosing breast
abnormalities
PET Scan
• Positron Emission Tomography
• Radioactive isotope is tagged to
substance used by specific cells and
injected into the blood
• Best way to show metabolism or specific
functional areas, good for determining how
well an organ is functioning, especially the
brain and heart
CAT vs PET
• CAT – 2D tomes are
reconstructed to show 3D
images of structure
• PET – radiopharmecuticals are
used to give 2D and 3D
images of function
Magnetic Resonance
Imaging
• Image produced
when body is
surrounded by
powerful
electromagnetic
waves
• Best way to show
structure in minute
detail
Magnetic Resonance Imaging
• Gives good image
of soft tissues
• Cannot use if metal
is implanted in
body
• Good for images of
any type of
structural damage
Sonogram
• sound waves
bounced off organs
produces image of
deep structures
• Only imaging
procedure safe for
fetus
• Also used for thyroid,
abdominal masses,
inner heart structure,
blood vessels
Contrast Medium
• Radio-opaque substance used to make
hard-to-see structure show up on image
• Used in CAT scans and fluoroscopy
Radio-opaque vs
Radiolucent
Radio-opaque Block x-rays
Shows up as light color
Radiolucent –
Passes x-rays through
Shows up as dark color
Fluoroscopy
Visualization of
moving structures
as contrast
medium moves
through body
Used with radioopaque
substances
GI series,
arteriograms
Cineradiography
• Filming images on fluroscope screen with
a video camera
How to process an imaging
request
• Check for allergies- if allergic to seafood the pt.
might be allergic to iodine found in many radioopaque dyes
• Age- below 12 may need extra help or sedation
• Weight- older MRI machines limited to max
300lb
• Pacemaker- may be damaged by exposure to
MRI
• Metal items in body- artificial joints or internal
fixation devices may contain metal that will heat
up or be dislodged by the test
Image quality
• Target structures must be visualized
• Proper view must be shown
• Image must be clear
***The imager must make sure the image is
of good quality before releasing the patient
from the unit****
Unit Preparation
• Safety- equipment and safety monitors
working properly
• Supplies- everything needed on hand
Commonly Visualized structures
radiographic and fluoroscopic
• Chest x-ray (CXR)- heart lungs ribs
• Upper GI series- esophagus, stomach,
small intestine
• Lower GI - colon
Patient Safety
• Check for previous imaging to prevent
repeat exposure
• Give instructions and check for
understanding
• Position correctly to prevent repeat
• Use gonadal shielding on children and
patients of reproductive age
• Ask all women for LMP
Worker safety
• Reduce exposure time
• Stay as far from radiation source as possible
and position body at right angle
• Use shielding appropriate for the test- lead
apron, lead gloves
• Wear appropriate radiation detection device
(dosimeter on front of body
1. Film badge- least accurate, good for 1 month
2. Thermoluminescent dosimeter- good for 3
months
3. Pocket ionizing chamber- most accurate
Workplace safety
• Geiger-Muller detector- detects quantity of
radiation in the workplace
• Victoreen condenser R-meter- used to
calibrate radiography equipment
Thermogram
• Media – infrared
camera captures
surface body heat
• Newer forms relate
metabolic activity
(function) to heat
given off