This test is also called a spiral CT scan. It uses X-rays to create detailed pictures of your lungs. To have the test, you lie still on a table as it passes through the center of the CT scanner. A CT scan is painless and noninvasive. It does not need any special preparation. You may be asked to hold your breath one or more times during the scan. A CT scan can show some abnormal areas that a chest X-ray might miss. But these areas often turn out not to be cancer. You may still need more invasive tests to be sure.
It’s not clear if spiral CT scans can find cancer in people who are not heavy smokers or who have not smoked at all. It’s also not clear if the test can find cancer in people younger than age 55. Studies of the spiral CT scan have only been on heavy smokers who were 55 to 74 years old.
Spiral CT scans also have some downsides. They find many abnormalities that turn out not to be cancer but that still need more testing to be sure. This can make people feel anxious. It may also mean unneeded tests such as more CT scans. And it might mean more invasive tests such as biopsies or surgery, even when a person doesn't have lung cancer. Spiral CT scans also use a small amount of radiation during each test.