A low-dose CT scan for lung cancer screening uses a significantly reduced amount of radiation compared to a standard CT scan, typically delivering about 1.5 millisieverts (mSv) or less of radiation. This dose is roughly equivalent to the natural background radiation a person receives over six months to a year, and it is about one-fifth to one-tenth the radiation dose of a conventional chest CT scan.
Low-dose CT (LDCT) scans are designed to produce detailed images of the lungs while minimizing radiation exposure. This is achieved by using specialized X-ray techniques combined with computer technology that tightly focuses the X-ray beam only on the lung area, sparing surrounding tissues from unnecessary radiation. The protocols for LDCT scans reduce radiation exposure by approximately 50 to 80 percent compared to standard CT scans, without compromising the ability to detect very small lung nodules or lesions that may indicate early lung cancer.
The scan itself is quick, usually taking less than a minute, and does not require contrast dye, which further simplifies the procedure and reduces risks. Radiologists who specialize in lung imaging interpret these scans, looking for tiny abnormalities often smaller than one centimeter, which can be early signs of lung cancer.
Because lung cancer is often detected late when symptoms appear, LDCT screening is particularly valuable for high-risk individuals, such as heavy smokers or former smokers aged between 50 and 80 years. Early detection through LDCT screening has been shown to improve survival rates by identifying cancer at a stage when it is more treatable.
While the radiation dose from a low-dose CT scan is higher than that of a standard chest X-ray, it remains low enough to justify its use in screening programs, especially given the potential life-saving benefits. The risk from this level of radiation is considered minimal compared to the risk of undetected lung cancer in high-risk populations.
In summary, a low-dose CT scan for lung cancer screening uses a carefully controlled, reduced radiation dose—about 1.5 mSv or less—that balances minimizing radiation exposure with the need for high-quality images to detect early lung cancer effectively. This approach has revolutionized lung cancer screening by enabling earlier diagnosis with a radiation dose that is safe for routine screening in appropriate patients.
