What to Expect from the Exam
The exam is quick and painless. There is no preparation required and you can eat before or after the exam. There is no need to drink an oral contrast material and there are no needles or medications used for this exam. You do not need to get changed for this exam as long as the clothing on your chest does not contain any metal. All jewelry should be removed.
You will lie on your back with your arms above your head. The table will move in and out of the CT scanner. You will need to hold your breath for the 10 seconds it takes to acquire the images of your lungs. You may leave after your exam. You do not need to wait for the results of your exam.
What are the risks associated with Low Dose CT (LDCT) Lung screening?
The risks associated with lung cancer screening include false positive and false negative results, incidental findings not related to lung cancer, and radiation exposure.
False positive findings
While LDCT lung screening can save lives, it has a high number of false positives, findings that are abnormal but turn out to be non-cancerous. Examples include a lung nodule caused by a scar or old infection, and small lymph nodes that are sometimes normally present in the lung. One out of 4 patients screened will have a finding in the lungs that requires further testing, but the majority (more than 97%) of these findings do not represent cancer. You may need further tests, such as more CT scans a PET/CT scan, referral to a specialist, a lung biopsy or surgery. In the National lung Screening Trial (NLST) about 1 in 4 participants had a false positive. In most cases all that was required was a short-term follow-up LDCT exam in 3-6 months.
False Negative Findings
Screening may not detect some cases of lung cancer. In the National Lung Screening Trial (NLST), about 4% of lung cancers were not detected at screening.
The LDCT lung screening exam also includes images of other areas of your body that are close to the lungs. In a small percentage of cases (5-10%), the LDCT exam will show an abnormal finding in one of these areas such your heart, aorta, lymph nodes, kidneys, adrenal glands, liver, spleen, or thyroid gland. This finding may not be serious; however, you may need to be examined further. Your health care provider who ordered the exam can help determine what, if any, additional testing you may need.
As with all CT exams, LDCT lung screening exposes you to certain amount of radiation. The amount of radiation is equal to about a quarter to one half of the naturally occurring background radiation one receives at sea level. This dose is about one quarter of a standard chest CT exam and about the same as a mammogram. It is difficult to document the exact amount of increased risk from radiation, but studies suggest that radiation slightly increases your incidence of cancer. It is important to know that in general, one in four people will develop cancer in their lifetime. When considered in this context, the risk of developing a cancer from a CT scan only slightly increases a person’s overall risk from baseline of 1 in 4.