Radiography (X-ray) - Bone
What is Bone Radiography?
Radiography, or an x-ray, as it is
most commonly known, is the oldest and most frequently used form
of medical imaging. Discovered more than a century ago, x-rays can
produce diagnostic images of the human body on film or digitally on a computer
screen.
X-ray imaging is the fastest and easiest way for a physician to view and
assess broken bones, such as skull fractures and spine injuries. At least
two images (from different angles) are taken and often three images are
needed if the problem is around a joint (knee, elbow or wrist). X-rays
also play a key role in guiding orthopedic surgery and in the treatment
of sports-related injuries. X-ray may uncover more advanced forms of cancer
in bones, although early screening for cancer findings requires other methods.
To this end, radiologists have developed alternative imaging methods that
do not rely on radiation, such as ultrasound and magnetic resonance imaging
(MRI). However, because x-ray was the first imaging modality, many people
(and medical imaging professionals) continue to use the term "radiology" to
include all types of imaging. Strictly speaking, though, radiology refers
to the use of x-rays.
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What are some common uses of the procedure?
Probably the most
common use of bone radiographs is to assist the physician in identifying
and treating fractures. X-ray images of the skull, spine, joints
and extremities are performed every minute of every day in hospital emergency
rooms, sports medicine centers, orthopedic clinics and physician offices.
Images of the injury can show even very fine hairline fractures or bone
chips, while images produced after treatment ensure that a fracture has
been properly aligned and stabilized for healing. Bone x-rays are essential
tools in orthopedic surgery, such as spinal repair, joint replacements
or fracture reductions.
X-ray images can be used to diagnose and monitor the progression of degenerative
diseases such as arthritis. They also play an important role in the detection
and diagnosis of cancer, although usually computed tomography (CT) or MRI
is better at defining the extent and the nature of a suspected cancer.
On regular x-rays severe osteoporosis can be visible, but bone density
determination for early loss of bone mineral is usually done on specialized,
more sensitive equipment.
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How should I prepare for the procedure?
There is no special preparation required for most bone radiographs. Once
you arrive, you may be asked to change into a gown before your examination.
You will also be asked to remove jewelry, eyeglasses and any metal objects
that could show up on the images and overlap important findings. Women
should always inform their doctor or x-ray technologist if there is any
possibility that they are pregnant.
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What does the x-ray equipment look like?
Radiography equipment consists of a large, flat table with a drawer that
holds a tray into which an x-ray film cassette is placed. Suspended above
the table is the apparatus that holds the x-ray tube that can be moved
over the body to direct the x-ray.
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How does the procedure work?
Radiography involves exposing a part of the body to a small dose of radiation
to produce an image of the internal organs. When x-rays penetrate the body,
they are absorbed in varying amounts by different tissues. Ribs, for example,
are dense and will block much of the radiation and, therefore, appear white
or light gray on the image. Soft tissue such as the liver or lungs will
appear darker because more radiation can pass through it to expose the
film.
The images may be placed on film or may be stored electronically on PACS
(picture archiving and communication systems). Films are usually stored
in a film jacket in the radiology department or in the doctor's office
for approximately seven years (unless the patient is a child, then until
age 21). Images may be digitally acquired or may be digitized from analog
images and can be stored on PACS.
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How is the procedure performed?
The technologist positions the patient on the examination table, places
a film holder (cassette) under the table in the area of the body to be
imaged. Sandbags or pillows may help the patient hold the proper position.
Then the technologist steps behind a radiation barrier and asks the patient
to hold very still without breathing for a few seconds. The radiographic
equipment is activated, sending a beam of x-rays through the body to expose
the film. The technologist then repositions the patient for another view,
and the process is repeated.
When your x-rays are completed you will be asked to wait until the technologist
checks the images for adequate exposure and motion.
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What will I experience during the x-ray procedure?
X-ray imaging itself is painless. Some discomfort may result from lying
on the table, a hard surface that may feel quite cold. Sometimes, to get
a clear image of an injury such as a possible fracture, you may be asked
to hold an uncomfortable position for a short time. Any movement could
blur the image and make it necessary to repeat the procedure to get a useful,
clear picture.
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Who interprets the results and how do I get them?
A radiologist is a physician experienced in bone x-ray and all other types
of radiology examinations. He or she will analyze the images and send a
signed report to your primary care or referring physician, who will inform
you on your test results. New technology also allows for distribution of
diagnostic reports and referral images over the Internet at many facilities.
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What are the benefits vs. risks?
Benefits
- X-ray imaging is useful to diagnose bone injury and disease, such as
fractures, bone infections, arthritis and cancer.
- Because x-ray imaging is fast and easy, it is particularly useful
in emergency diagnosis and treatment.
- X-ray equipment is relatively inexpensive and widely available in
physician offices, ambulatory care centers, nursing homes and other
locations, making it convenient for both patients and physicians.
Risks
- X-rays are a type of invisible electromagnetic radiation and create
no sensation when they pass through the body. Modern x-ray techniques
use only a fraction of the x-ray dose that was required in the early
days of radiology.
- Women should always inform their doctor or x-ray technologist if there
is any possibility that they are pregnant.
- During a single x-ray exposure, a patient is exposed to approximately
20 milliroentgens of radiation. To put this into perspective, we
are all exposed to approximately 100 milliroentgens of radiation each
year from sources like the ultraviolet rays of the sun and small traces
of radioactive isotopes, such as uranium found in soil.
Radiation risks are further minimized by:
- The use of high-speed x-ray film that requires only very small
amounts of radiation to produce an optimal
image.
- Technique standards established by national and international
guidelines that have been designed
and are continually reviewed by national and international radiology
protection councils.
- Modern, state-of-the-art x-ray systems (including mammography
systems, angiographic equipment,
labs and CT scanners) that have very tightly controlled x-ray beams
with significant filtration and x-ray dose control methods. Scatter
or stray radiation is minimized and those parts of a patient’s
body not being imaged receive minimal exposure.
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What are the limitations of Bone Radiography?
While x-ray images are among the clearest, most detailed views of bone,
they provide little information about the adjacent soft tissues. In the
case of a knee or shoulder injury, for example, an MRI may be more useful
in identifying ligament tears, joint effusions or other problems. Even
in the evaluation of a traumatic injury to the bone that does not cause
a visible crack, MRI can detect a so-called bone "bruise." Other
imaging modalities, such as positron emission tomography (PET), bone scanning
or CT, may be more effective in diagnosing cancer metastases (spread) to
bone or primary bone tumors. MR is especially useful for imaging the spine
because the bones and the spinal cord are evaluated. Ultrasound (sound
waves instead of ionizing radiation) has also been useful in injuries around
joints and in evaluating hips in children for congenital problems.
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