Download Digital Imaging and Radiology

Digital Imaging and
Radiology
Traditional x-rays
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Use electromagnetic waves to make pictures
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New imaging techniques use computers to
generate pictures of internal body organs
Computers can make pictures using
mathematical information
Newer Technologies
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Computerized tomography is a diagnostic procedure
that uses special x-ray equipment to obtain cross
sectional pictures of the body.
The CT computer displays these pictures as detailed
images of organs, bones, and other tissues.
In cancer, CT is used to detect a tumor, provide
information about the extent of the disease, help plan
treatment, and determine whether the cancer is
responding to treatment
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A CT scan uses slightly more radiation than a chest x-ray, but the benefits generally
outweigh the risks
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During a CT scan, the person lies very still on a table. The table slowly passes
through the center of a large x-ray machine. The person might hear whirring sounds
during the procedure. People may be asked to hold their breath at times, to prevent
blurring of the pictures.
Often, a contrast agent, or “dye,” may be given by mouth or injected into a vein
before the CT scan is done. The contrast dye can highlight specific areas inside the
body, resulting in a clearer picture.
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Magnetic Resonance Imaging
(MRI)
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MR imaging uses a powerful magnetic field,
radio waves and a computer to produce
detailed pictures of organs, soft tissues, bone
and virtually all other internal body structures.
The images can then be examined on a
computer monitor or printed. MRI does not use
ionizing radiation (x-rays).
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In most cases, an MRI exam is safe for
patients with metal implants, except for a few
types. People with the following implants
cannot be scanned and should not enter the
MRI area:
internal (implanted) defibrillator
cochlear (ear) implant
clips used on brain aneurysms
Positron Emission Tomography
A PET scan, unlike a normal X-ray, can detect cancer
before organ or gland enlargement occurs. Here a
normal X-ray of the chest (left) is compared with a
PET scan of the chest producing normal results (top
right) and a PET scan revealing cancer that's spread to
the lymph nodes (bottom right).
Advantages of digital imaging
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No developing process
Copies are as good as originals
Viewed on computer screen
Can be transmitted over telephone lines
Less radiation
More flexible
Can be highlighted or enhanced
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X-rays are most frequently used in orthopedics and dentistry
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As with many of mankind's monumental discoveries, X-ray technology
was invented completely by accident. In 1895, a German physicist named
Wilhelm Roentgen made the discovery while experimenting with electron
beams in a gas discharge tube. Roentgen noticed that a fluorescent screen
in his lab started to glow when the electron beam was turned on. This
response in itself wasn't so surprising -- fluorescent material normally
glows in reaction to electromagnetic radiation -- but Roentgen's tube was
surrounded by heavy black cardboard. Roentgen assumed this would have
blocked most of the radiation.
Roentgen placed various objects between the tube and
the screen, and the screen still glowed.
Finally, he put his hand in front of the tube, and saw the
silhouette of his bones projected onto the fluorescent
screen. Immediately after discovering X-rays
themselves, he had discovered their most beneficial
application
Mammography is a traditional x-ray
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Mammography is a low-powered x-ray technique that captures
a picture of the internal structure of the breast. Additional
angles and magnified views are taken of suspicious areas.
A mammogram may help in the diagnosis of breast problems,
including cancer.
It is recommended a woman have a baseline mammogram
at age 40, followed by a
mammogram every couple of
years until age 50.
After 50, a woman should
have a mammogram every year.
Ultrasound can distinguish between
cysts and tumors
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It is used along with mammograms
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Does not use radiation but high frequency
sound waves
Computer Tomography
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Uses x-rays and digital technology to produce
a cross-sectional image of the body. (Enhanced
CT’s use dye)
Magnetic Resonance Imaging
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Produces images of soft tissue within the body
The image is produced by a computer with a
magnetic field that is 25,000 times stronger
than the earth’s magnetic field
Positron Emission Tomography
(PET)
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Scans can be two or three dimensional
Used in the study of Alzheimer’s and
Parkinson’s disease
They produce pictures of activity and function
Interventional Radiology
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Treats an ever-widening range of conditions inside
the body from outside the body by inserting various
small instruments or tools, such as catheters or wires,
with the use of various x-ray and imaging techniques
(i.e., CT scanners, MRI scanners, ultrasound
scanners).
Interventional radiology offers an alternative to the
surgical treatment of many conditions and can
eliminate the need for hospitalization, in some cases
Surgical biopsies have now been replaced with needle
biopsies
Stereotactic Radiosurgery
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Stereotactic radiosurgery (SRS) treats brain disorders with a
precise delivery of a single, high dose of radiation in a one-day
session. Focused radiation beams are delivered to a specific
area of the brain to treat abnormalities, tumors or functional
disorders.
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Is the very precise delivery of radiation to a brain tumor with
sparing of the surrounding normal brain.
Stereotactic Radiosurgery
cont.
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Uses a gamma knife which is a painless device
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The gamma knife uses multiple beams of
radiation converging in three dimensions to
focus precisely on a small volume, such as a
tumor, permitting intense doses of radiation to
be delivered to that volume safely.
Focused ultrasound surgery
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Uses sound waves which create a powerful
ultrasonic beam
High-intensity ultrasound energy focused on a
small target volume raises the tissue
temperature high enough to destroy it. This is
similar to the manner in which sunlight
focused by a magnifying glass can create
sufficient heat to start a fire. The use of heat to
destroy tissue is called thermal ablation