Low-Dose CT Scan: What It Is, Who Needs It, and What To Expect

Doctor beginning a patient's low-dose CT scan

Key takeaways:

  • A low-dose CT scan (LDCT) is recommended for populations who are at high risk of lung cancer or coronary heart disease.
  • The screening is fast, painless, and has a low risk of side effects.
  • LDCT scans are often covered by insurance providers for people at high risk of lung cancer (30-pack year smoking history), but check with your provider to be sure.

If you are considering screening for lung cancer with a low-dose CT scan, you might feel some level of anxiety. This is understandable, so our goal is to help you decide whether an LDCT scan is for you.

With a low-dose CT scan, you can set your mind at ease regarding lung cancer. The best kind of cancer detection is an early one, and an LDCT is the best way to screen for lung cancer.

In this article, we’ll review what a low-dose CT (LDCT) scan is, who might especially benefit from one, and what will happen if you get one. We’ll also review lung cancer symptoms, the risks and benefits of LDCT screenings, and how insurance companies cover these scans.

What are low-dose CT scans?

A low-dose CT scan (LDCT) is the medical imaging modality recommended by specialists (such as the US Preventative Task Force) for lung cancer screening. Low-dose CT scans are a computed tomography technique that uses X-rays to create internal images of your body. The images show the difference in density between the tissues penetrated by the X-ray waves. This technique helps detect soft tissue, i.e., abnormalities.

Contrary to traditional chest radiography, which is a two-dimensional image, LDCT has a three-dimensional compound. The X-rays equipment takes multiple pictures at different angles around the patient while they slowly move forward. Each picture is then computed, processed, and reconstructed as a volume. It is now possible for the radiologists to look at cross-sectional images of their choice necessary for a more accurate diagnosis.

Using low-dose computed tomography in the front lines of early detection of lung cancer decreases the mortality rate due to lung cancer by 20% compared to conventional chest X-rays. The low dose of radiation generates images with sufficient quality to improve lung cancer diagnosis.

What is lung cancer?

Woman's face beside pleasant design

Before you learn more about LDCT screening, we should back up and discuss what lung cancer is.

Lung cancer is a dysregulated proliferation of cells that belong to the lung. Lung cancer categories relate to the type of cells affected. The two principal types are Small Cells Lung Cancer (SCLC) and Non-Small Cells Lung Cancer (NSCLC). SCLC accounts for 10-15% of lung cancer cases, while the NSCLC accounts for 85-90%: It is the most common of all lung cancers. However, SCLC is more aggressive than NSCLC. In the United-States, lung cancer is the leading cause of cancer deaths for all genders. The American Cancer Society estimates in 2020, more than 135,720 people have died of lung cancer in the U.S.

Tobacco is the main risk factor in developing lung cancer. Cigarette smoking and secondhand smoke cause about 90% of lung cancer deaths. Be aware that you can reduce your risk of lung cancer by quitting smoking.

Air pollution, radiation exposure, and asbestos are also important lung cancer risk factors. If you reduce your exposure to these particles, you could then reduce your risk of developing lung cancer.

Lung cancer symptoms

Lung cancer is challenging to diagnose based solely on symptoms. Many similarities exist with other pulmonary pathologies. Nevertheless, you should consult your primary care doctor if you experienced at least one of the following symptoms (non-exhaustive list):

  • Cough that won’t go away
  • Coughing up blood
  • Difficulty breathing
  • Chest pain
  • Repeated bronchitis and/or pneumonia.

The appearance of symptoms means the cancer is already in an advanced stage.

To detect lung cancer at an early stage, you need to be proactive. The U.S. Preventive Services Task Force highly recommends regular screening for an asymptomatic population with a high risk of lung cancer using an LDCT scan.

Who needs lung cancer screenings?

Eligibility for lung cancer screening is tightly correlated with age and lifestyle. As mentioned earlier, smoking is the biggest risk factor in developing lung cancer. You are 30 times more at risk. Healthcare professionals define smoking habits based on your history of smoking (pack-per-year history). Packs per year are defined as an average of one pack of cigarettes smoked per day over a number of years.

If you smoke, you are part of the high-risk lung cancer population. You need regular lung cancer screenings if you are between 55-80 years old and:

  • You are a current smoker or former smoker that quit smoking within the past 15 years.
  • You reached at least 30 pack-years or showed a history of a heavy smoker.
  • You have no signs or symptoms of lung cancer.

The lung cancer screening guidelines currently used have been validated in a clinical trial entitled the National Lung Screening Trial (NLST), sponsored by the National Cancer Institute.

If you are at a high risk of developing lung cancer, the NLST recommends annual screening using an LDCT scan. More information can be found on the American Cancer Society website.

What should you expect in a low-dose CT scan?

Patient beginning a low-dose CT scan

If you are considering your first appointment for a low-dose CT scan, you should know an LCDT is quick and painless. Here is what to expect.

  • The CT scanner is shaped like a big circle with a bed sliding toward the circle’s center.
  • To start the procedure, you will be asked to lie on the bed, belly up.
  • The bed will slide toward the center of the circle until your chest enters the field of view.
  • Before launching the scan, a technologist will ask you to take a deep breath and hold it until the end of the scan.
  • The scan will last between 5 and 10 seconds, during which the bed will slowly keep moving.
  • An image will be recorded, stored, and processed at each incrementation to create the final render.
  • The entire procedure will take no longer than 5-10 minutes, including the time you’ll spend changing into scrubs, and doing small talk with your technician.

The radiologists are looking for isolated and dense abnormalities on the final scan. These are called lung nodules or solitary pulmonary nodules (SPN). In 95% of the cases, these nodules are benign.

However, above a certain size (6 mm diameter or 100 mm³), your doctor is likely to recommend a follow-up scanning session six months to a year later to assess any potential changes. If the nodule has grown since the last visit, further investigations must be performed. If necessary, a PET scan will determine your non-invasively inflammatory status. A biopsy will be performed for histopathology analysis.

What are the risks and benefits of an LDCT screening?

As with any medical imaging modalities, lung cancer screening using LDCT has risks we should know going in:

  • Radiation exposure is known to be a risk factor in developing cancer. However, the amount of radiation emitted by a low-dose CT is 90% lower than the traditional chest CT. Therefore, the radiation dose taken by the subject is unlikely to cause any side effects.
  • False-positive results happen when large lung nodules end up not being cancerous. Patients then undergo further potentially harmful medical exams for no reason. Overdiagnosis accounts for 18% of the cases. Keep in mind that evaluating whether the screening indicates cancer is a tricky call that your doctor has to make.
  • False-negative results happen when small nodules don’t look suspicious on the scan but are cancerous. Hopefully, this type of nodule will be detected at the visit. Meanwhile, researchers are working hard to improve such medical equipment’s sensitivity and specificity for an accurate diagnosis.
  • A true-positive result means that the nodule is cancerous. Further medical exams will determine if it has been detected early enough to be curable.

The benefit of a scan is that it can help you detect lung cancer before it becomes symptomatic. It means it’s still at an early stage. According to the American Cancer Society, localized early-stage lung cancer has a five-year survival rate of 61%, compared to less than 6% for late-stage, metastatic lung cancer.

Several treatments exist to help eradicate cancer. Surgical resection of the nodules completed with chemotherapy is commonly used to treat cancer. It shows better efficiency if taken at an early stage. Immunotherapy is also indicated in several types of lung cancer.

How do insurance companies cover LDCT scans?

If you meet the criteria suggested by the U.S. Preventive Services Task Force (USPSTF), your insurance will likely cover the LDCT screening test as cancer care.

Make sure your plan covers annual lung cancer screening, talk to your healthcare providers. You will find more specifications about the coverage on the official U.S. government site for Medicare.

If you don’t meet the criteria suggested by the USPSTF, you may still be at risk for lung cancer. If you have a history of heavy smoking, you are likely at higher risk for lung cancer.

At Ezra, we offer affordable, direct-to-consumer LDCT scans, which are paid out of pocket. The scans are targeted at individuals at higher risk of lung cancer for whom an insurance company would not cover an LDCT scan.

Ezra helps you prepare.

Lung cancer screening using a low-dose CT scan can save your life.

If you are 55 or older and at high risk of lung cancer, ask your doctor for an annual screening. At Ezra, we’ve found the best defense against cancer is early detection. And we don’t only scan for lung cancer — our full-body MRI scan screens for cancer in up to 14 organs.

Note that annual lung cancer screening is no justification to keep smoking. The best way to prevent lung cancer suffering is to quit smoking and stay away from any clouds of dust containing asbestos and other harmful volatile compounds.

A healthy lifestyle may help prevent cancer. But low-risk doesn’t mean zero risks. Take our five-minute questionnaire to understand your risk of cancer.