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Understanding a Low-Dose CT Scan for Lung Cancer Screening

A computed tomography (CT) scan is a type of imaging test. It uses X-rays and a computer to make detailed pictures of your lungs and other soft tissues, organs, blood vessels, and bones. These images are better than regular X-rays. They can give more details about injuries or diseases of the chest organs. A CT scan exposes you to a small, directed amount of radiation as part of the imaging process. A low-dose CT (LDCT) scan delivers less than a normal CT scan. It's also called a spiral CT scan.

In a CT scan, an X-ray beam moves in a circle around your body. It takes many images of the lungs and inside the chest. A computer processes these images. They are then displayed on a monitor.

Why an LDCT is done

LDCT is used in screening for lung cancer. The goal in screening is to find cancer before it causes symptoms so it can be treated. This test is useful for the early detection of lung cancer when it’s more likely to be cured. Yearly lung cancer screening with a low-dose CT scan can reduce the risk of dying from lung cancer for those at high risk. High-risk people include those that are current or former smokers older than 55 and younger than 80. You may consider this test if:

  • You are at high risk

  • You are a long-time heavy smoker. This means about 1 pack a day for at least 30 years or 2 packs a day for at least 15 years.

  • You were a heavy smoker but quit within the last 15 years

Your healthcare provider may have other reasons to advise this test.

How an LDCT is done

A CT scanner is a large, round piece of equipment with a large hole in the center. You will lie on a table that moves through the center of the scanner. The machine rotates around you and makes a whirring noise. You will need to stay very still. You may be asked to take a deep breath. The test is painless. It does not need any special preparation. The technician is in the next room and can watch you through a window. He or she can communicate with you through a two way intercom.

Technician preparing woman for CT scan.

Risks of an LDCT

  • False positive results. Sometimes this test can show lung nodules that are not cancerous. This can lead to unnecessary biopsies or other tests.

  • Radiation exposure. Although this test uses low-dose radiation compared with a regular CT scan, it uses about 20 times more radiation than a typical chest X-ray.

Talk with your provider about the benefits and risk of having an LDCT. If you are at high risk, the benefits may be greater than the risks.

© 2000-2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.