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Chest X-Ray (cont.)

Normal Chest X-ray Test

As mentioned earlier, the image on chest X-ray film is in shades of black and white, similar to a negative of a regular photograph. The shadows on a chest X-ray test depend on the degree of absorbed radiation by the particular organ based on its composition. Bony structures absorb the most radiation and appear white on the film. Hollow structures containing mostly air, such the lungs, normally appear dark. In a normal chest X-ray, the chest cavity is outlined on each side by the white bony structures that represent the ribs of the chest wall. On the top portion of the chest is the neck and the collar bones (clavicles). On the bottom, the chest cavity is bordered by the diaphragm under which is the abdominal cavity. On either side of the chest wall, the bones of the shoulders and arms are easily recognizable.

Inside the chest cavity, the vertebral column can be seen down the middle of the chest, splitting it nearly in equal halves. On each side of the midline, the dark appearing lung fields are seen. The white shadow of the heart is in the middle of the field, atop the diaphragm and more to the left side. The trachea (wind pipe), aorta (main blood vessel exiting the heart), and the esophagus descend down the middle, overlapping the vertebral column.

Abnormal Chest X-ray Test

Many abnormalities can be detected on a chest X-ray test. Common abnormalities seen on a chest X-ray test include:

  • pneumonia (abnormally white or hazy shadow on the lung fields that would normally look dark);
  • abscess in the lung (lung abscess);
  • fluid collection between the lung and the chest wall appearing whiter than the lungs and making the sharp lung borders on the film more hazy (pleural effusion);
  • pulmonary edema (fluid build-up in the lung or its blood vessels) seen as diffuse haziness on the lung fields (for example, from congestive heart failure);
  • enlarged heart size (or cardiomegaly);
  • broken ribs or arm bones (irregularity in the structure and shape of any of the ribs or the humerus bone of the arm);
  • broken vertebrae or vertebral fractures;
  • dislocated shoulders;
  • lung cancer or other lung masses (irregular and abnormal shadow on the lung fields);
  • cavities in the lungs or cavitary lung lesions (tuberculosis, sarcoidosis, etc.);
  • abnormal presence of air between the chest wall and the lung creating a distinct black shadow (darker than the lung fields) between the border of the lung tissue and the inside border of the chest wall (pneumothorax);
  • hiatal hernia (protrusion of the upper portion of the stomach into the chest cavity); and
  • aortic aneurysm (dilated aorta - a widening of the midline of the chest overlying the vertebral column).

These are some of the common abnormal findings that can be seen on chest X-ray test. There are many other less common abnormalities that can be detected on chest X-ray tests.

Chest X-ray Test Risks

Risks associated with having a chest X-ray test are minimal, but they need to weighed against the benefits for each individual case. Chest X-rays release radiation to the body in order to produce an image. The amount of radiation, however, is very small and it does not last in the body after the image is taken. Pregnant women who require a chest X-ray are advised to notify the doctor and the X-ray technician so proper precautions can be taken to minimize radiation exposure to the fetus.

Obtaining Chest X-ray Test Results

After the chest X-ray test is read by the doctor, a report is typically generated and placed in the patient's chart. If the X-ray is performed in a radiology facility, the report from a radiologist is usually sent to the doctor who had ordered the test. The written report can also be provided to the patient after proper forms to release medical information are signed.

Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine

REFERENCE: "Chest X-Ray."

Medically Reviewed by a Doctor on 3/1/2016

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