CT Scan FAQs

  • If you are at risk of lung cancer, you may want to have low-dose CT scan that can help detect lung cancer at its earliest and most curable stage.  The best hope for curing lung cancer is finding it as early as possible.  The Early Lung Cancer Action Program (ELCAP research showed that annual CT screening can find 85% of lung cancers in their earliest, most curable stage (Lancet 1999; 354:99-105). A CT scan can detect tiny spots on your lungs (called ‘nodules’) that may indicate lung cancer in this early stage (New England Journal of Medicine 2006; 355: 1763-1771).  The ELCAP research results together with the National Lung Screening Trial (NLST) (New England Journal of Medicine 2011; 365:395-409) results led to the current recommended program of clinical screening.

  • Advances in CT scanning now allow individuals to undergo a painless, non-invasive scan that takes less than 20 seconds.  In most cases, you do not even have to change your clothes.

    Prior to scanning, you should fill out our simple questionnaire that can be completed in less than half an hour.  A trained healthcare navigator will assist you throughout the process.

  • A radiologist who has had special training and is experienced in interpreting these types of tests analyzes each CT scan.

    The radiologists will discuss any findings and necessary follow-up with the participant's physician.

  • CT screening uses a lower dose compared to standard CT scans. We strive to keep the dose between 1-2 mSv (millisieverts) or lower, although for individual patients it may be slightly higher than this value. As a comparison, average background radiation in the US is approximately 3 mSv/ year and in Denver, Colorado, due to the higher altitude it is 11.8.  Another comparison is that the exposure of a low-dose CT scan is less than a mammogram which is below 0.6 mSv.

  • Yes. Old or new pneumonia, tuberculosis, or emphysema may be detected.


  • A limited evaluation will be done. The radiologists are able to see heart size and can detect calcifications in the coronary arteries when present. It also can detect abnormal enlargements of the main blood vessels leading out of the heart. These results will be reported to your doctor.

  • The benefits of lung cancer screening CT scans are highest for those with significant lung cancer risk.

    ELCAP and its expanded research collaboration, the International ()I-ELCAP has focused on patients at a high risk for lung cancer. Several factors contribute to lung cancer risk.  They are age; smoking history; environmental exposure to carcinogens like asbestos, beryllium, uranium, or radon; and exposure to second hand smoke. The older you are and the more you've smoked or been exposed to smoke and other carcinogens, the higher your risk.

    Additionally, I-ELCAP research has shown that women were twice as likely as men to develop lung cancer when both had similar smoking histories. Click here for more information about how lung cancer affects women.

    We encourage you to contact one of our member sites to make an appointment and learn more about how you personally may benefit from a lung cancer screening CT.

  • The CT (Computed Tomography) scan or the CAT (Computer-Aided Tomography) scan is a diagnostic procedure that takes a detailed cross-sectional x-ray picture of a "slice" of the body.

    To get a CT scan, the patient lies very still on a table, which is slowly moved horizontally while the x-ray machine rotates around the patient and takes pictures from many angles.  A computer then combines the pictures into a very detailed cross-sectional image.  The length of the procedure depends on the areas to be x-rayed.  For the chest area, the procedure takes about 20 seconds.

    CT scans can show the shape, size and the exact location of organs and tissues in any "slice" of the body more clearly than other diagnostic tools.  This technique can help find enlarged lymph nodes, which might contain cancer that has spread from the lung.  CT scans are more sensitive than routine chest x-rays in finding early lung cancers.  CT scans are also used in detecting masses in the liver, adrenal glands, brain and other internal organs that may be affected by the spread of lung cancer.

  • Recent articles published in Archives of Internal Medicine, "Projected Cancer Risks From Computed Tomographic Scans Performed in the United States in 2007" and "Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer" raise concerns about the potential risks associated with radiation. The radiation doses considered in those articles was based on standard dose scans rather than the low dose we currently employ in our research and therefore are substantially higher doses than participants in screening studies are likely to receive.

    Nevertheless, they remind us of the need to continually examine our protocols so that we continue to lower the dose we use while still maintaining appropriate image quality. The doses considered in those articles were as high as 90 mSv (millisieverts) for abdominal CT scans and for standard chest CTs as high as 24 mSv with a median of 8 mSv. They did not evaluate scans using the lower doses that we recommend in our research where we strive for the lowest dose possible, typically 1 or 2 mSv or lower, although for individual patients it may be slightly higher than this value.

    As a comparison, average background radiation in the US is approximately 3 mSv/ year and in Denver, Colorado, due to the higher altitude it is 11.8 mSv/year, and the dose allowed to people who work in the radiation field is 50 mSv/ year.

    It should also be recognized that the conclusions of these articles are not universally accepted. For example, the American College of Radiology said in a press release that,

    "No published studies show that radiation from imaging exams causes cancer. The conclusions of the authors of the Archives’ studies rely largely on data which equates radiation exposure and effects experienced by atomic bomb survivors in Japan to present day patients who receive computed tomography (CT) scans. Most CT is performed in controlled settings and results in limited radiation exposure to a small portion of the body. Atomic bomb survivors experienced instantaneous exposure to the whole body. CT exams expose patients solely to X-rays. Atomic blast survivors were exposed to X-rays, particulate radiations, neutrons, and other radioactive materials. The known biological effects are very different for these two scenarios. Cancer assumptions based on this paradigm should be considered, but not accepted as medical fact.

    Also, the articles - after excluding patients with cancer or within five years of the end of life - assumed that those undergoing CT scanning have the same life expectancy as the general population. This is not accurate, so the estimates are undoubtedly high. Moreover, 25 percent of people in the United States die of cancer with a life time incidence of 40 percent, about 1.5 million new cancers per year. The 29,000 [only 4,100 from standard Chest CT] figure, if even close to accurate, is overall a very small risk versus the immediate, proven life saving benefits of CT."

  • Below are 2 videos that fully describe the CT experience, including an actual CT scan. Click on either to download keeping in mind that the movies are large files (approximately 9-16 MB), and are in the Quicktime format (plugin available free from www.apple.com)

    More information about the screening process can be found here.