| Radiography (X-ray) - Chest
What is Chest Radiography? Back to Top
The chest x-ray is
the most commonly performed diagnostic x-ray examination. Approximately
half of all x-rays performed in medical institutions are chest x-rays.
A chest x-ray is usually done for the evaluation of lungs, heart and
chest wall. Pneumonia, heart failure, emphysema, lung cancer and other
medical conditions can be diagnosed or suspected on a chest x-ray.
Traditionally, chest x-rays have been performed prior to employment,
prior to surgery or during immigration. The use of "routine" chest
x-rays is being reevaluated because there is a lack of evidence for
their usefulness, and many insurance companies no longer pay for these
"routine" x-rays performed in the absence of specific signs, symptoms
or medical conditions.
What are some common uses of the procedure? Back to Top
A
chest x-ray is typically performed as the first imaging test for
symptoms of shortness of breath, a bad or persistent cough, chest pain,
chest injury or fever. Individuals with known or suspected medical
conditions such as congestive heart failure or cancer may undergo chest
x-rays to follow their response to treatment, or to determine changes
that would require a change in their medical management.
How should I prepare for the procedure? Back to Top
This
procedure requires no special preparation. Women should always inform
their doctor or x-ray technologist if there is any possibility that
they are pregnant.
What does the x-ray equipment look like? Back to Top
The
most common radiography equipment used for chest x-rays consists of a
box-like apparatus containing the recording material—such as film or a
digital recording plate against which the individual places his/her
chest—and the apparatus containing the x-ray tube, usually positioned
about six feet away. In some instances, the radiography equipment
consists of a large, flat table with a drawer that holds an x-ray film
cassette or a digital recording plate. With this arrangement, the x-ray
tube is suspended above the table.
How does the procedure work? Back to Top
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 parts of the
anatomy. The ribs and spine, for example, absorb much of the radiation
and appear white or light gray on the image. Lung tissue absorbs little
radiation and appears dark on the image. Depending upon the type of
image-recording medium, chest x-rays can be maintained as hard-copy
film for filing or, more commonly, as filmless digital images that are
archived electronically. Digital images can also be transferred for
storage onto CD-ROM. Stored images may be used to compare with later
images if illness develops. Indeed, historical comparison films are
often very important in the decision process as to whether a finding is
clinically important or not.
How is the procedure performed? Back to Top
Patients must
remove their clothing, including undergarments that may contain metal.
Most medical centers will give the patient a loose-fitting gown to
wear. Patients will also be asked to remove all metallic jewelry that
may interfere with the x-rays. Normally, a frontal or posteroanterior
view is obtained, in which the patient stands with the chest pressed to
the photographic plate, with hands on hips and elbows pushed in front
in a somewhat exaggerated position. The technologist will ask the
patient to be still and to take a deep breath and hold it.
Breath-holding after a deep breath reduces the possibility of a blurred
image and also enhances the quality of the x-ray image, since
abnormalities in air-filled lungs are easier to see than in deflated
lungs. Next, the technologist walks into a cubicle or small room to
activate the radiographic equipment, which sends a beam of x-rays from
the x-ray source behind the patient, through the patient's chest, to
the recording medium (film or digital cassette). Some equipment is
designed to accommodate patients who cannot stand for chest x-rays.
The technologist may need to take additional views to properly see
all parts of the chest or may take a side view, or lateral view, of the
chest. For a lateral view, the patient stands sideways to the
photographic plate with arms elevated, and the process is repeated.
Views from other angles may be obtained if the radiologist needs to
evaluate additional areas of the chest. Finally, a chest x-ray may be
repeated within hours, days or months to evaluate for any changes.
These repeated, sequential examinations are called serial chest x-rays.
When the chest x-rays are completed you will be asked to wait until
the technologist checks the images for motion and makes sure that the
entire chest is included. Ultimately, a radiologist will interpret the
chest x-ray images using a lighted view box to review films or a
computer and monitor to review digital images.
What will I experience during the x-ray procedure? Back to Top
This
is a painless procedure. The primary discomfort may come from the
coldness of the recording plate. Individuals with arthritis or injuries
to the chest wall, shoulders or arms may have discomfort trying to
maintain position for the chest x-ray. In these circumstances, the
technologist will assist you in finding a position that still ensures
diagnostic image quality.
Who interprets the results and how do I get them? Back to Top
A
radiologist, who is a physician specifically trained to supervise and
interpret radiology examinations, will analyze the images and send a
signed report with his or her interpretation to your primary care
physician or other health care provider, who will inform you of your
test results. New communications technology also allows for
confidential distribution of diagnostic reports and digital images over
the Internet at many facilities.
What are the benefits vs. risks? Back to Top
Benefits
- A physician may recommend a chest x-ray for a patient
with shortness of breath, a bad or persistent cough, chest pain or a
chest injury. In the instances of pneumonia, the site of pneumonia will
appear white on the image.
- A chest x-ray may also show advanced emphysema, as well as other diffuse lung conditions, such as pulmonary fibrosis.
- Lung
cancers and tumors that spread to the lung may be visible on a chest
x-ray. However, lesions that are small or superimposed on normal
structures may not always be visible.
- Heart
irregularities, an enlarged heart, abnormal heart anatomy or congestive
heart failure caused by fluid around the heart (pericardial effusion)
may also be visible on a chest x-ray.
- Pleural
effusions (fluid around the lungs) on one or both sides can be
detected. Usually the cause of such fluid may be deduced from clinical
data or other findings on the chest x-ray, but it may be necessary to
sample the fluid to determine its cause.
Risks
- X-rays are a type of electromagnetic radiation, are
invisible and create no sensation when they pass through the body. The
chest x-ray is one of the lowest radiation exposure medical
examinations performed today.
- Special care is taken
during chest x-ray examinations to ensure maximum safety for the
patient by paying attention to correct x-ray beam energies. Shielding
the abdomen and pelvis with a lead apron helps reduce unnecessary
radiation to the abdomen and pelvis. Women should always inform their
doctor or x-ray technologist if there is any possibility that they are
pregnant.
- The effective radiation dose from this
procedure is about 0.1 mSv, which is about the same as the average
person receives from background radiation in 10 days.
See the Safety page for more information about radiation dose.
Radiation risks are further minimized by:
- 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 that have tightly controlled x-ray beams
with significant x-ray beam filtration and dose control methods. Thus,
stray or scatter radiation is minimized, and those parts of a patient's
body not being imaged receive minimal exposure.
What are the limitations of Chest Radiography? Back to Top
The
chest x-ray is a very useful examination, but it has limitations. Some
conditions of the chest will not show up on the image. Therefore, a
normal chest x-ray does not necessarily rule out all problems in the
chest. For example, patients with asthma exacerbations can have a
normal chest x-ray. There are some cancers that are too small or are
difficult to visualize and may not be identified. Blood clots to the
lungs (pulmonary embolism) cannot be seen on chest x-rays and require
additional study.
A chest CT may be requested to further clarify a finding seen on the
chest x-ray or to look for an abnormality not visible on a chest x-ray
in order to answer the clinical problem. The degree of involvement of
the lung, as well as the distribution of disease and anatomic location,
may be better evaluated with chest CT to help aid in diagnosis. Some
diseases, such as chronic lung disease, are frequently evaluated with
HRCT (high-resolution CT).
The chest x-ray and the physical examination should be correlated.
The information each procedure provides can give the physician a
clearer understanding of the patient's health. Back to Top |
