Mastering Lung Cancer Screening Methods: What is Low-Dose CT (LDCT)?

Low-dose chest CT (LDCT) is widely used as the most effective method for early detection of lung cancer. Let's delve into how this examination method differs from conventional chest X-rays and why it is considered optimal for lung cancer screening.

 

What is Low-Dose CT (LDCT)?

LDCT is a type of 'Computed Tomography (CT),' an imaging diagnostic method that passes X-rays through the human body from various angles, then reconstructs the absorption differences using a computer to obtain cross-sectional or three-dimensional images of the body. As its name 'low-dose' suggests, it significantly reduces radiation exposure to about 1/8th of that of a general chest CT scan. This characteristic allows it to be used for regular screenings aimed at early detection of lung cancer.  

 

Chest X-ray vs. Low-Dose CT: Why LDCT?

While chest X-ray imaging is the most basic and fundamental examination for diagnosing chest diseases, it has clear limitations in the early detection of lung cancer. Chest X-rays typically only show lung lesions that are at least 5mm in size, and it is often difficult to detect lesions in certain areas, such as behind the heart or where bones overlap. Early lung cancer, in particular, is very difficult to detect with simple chest X-ray imaging.  

In contrast, LDCT has excellent resolution, capable of detecting lung nodules approximately 10 times smaller than those visible on chest X-rays, including microscopic nodules under 5mm. It is common for people to worry about lung cancer when they are informed of an 'abnormal shadow' on a chest X-ray during a health check-up, but such shadows do not necessarily mean lung cancer. In such cases, it is necessary to perform a low-dose CT scan to precisely confirm what abnormalities, if any, are present in the lungs.  

 

Key Advantages of Low-Dose CT

LDCT has become the standard for lung cancer screening due to several clear advantages:

• Improved Early Detection Rate: In a domestic pilot project, LDCT showed a high early detection rate of 69.6% for lung cancer. This plays a crucial role in increasing the success rate of lung cancer treatment.  
• Reduced Mortality: Foreign clinical trials have also confirmed that LDCT screening significantly reduces lung cancer mortality compared to chest X-ray screening.  
• Smoking Cessation Induction Effect: When lung cancer screening was linked with smoking cessation counseling, more than half of the participants either quit smoking (20.1%) or reduced their smoking amount (30.5%). This demonstrates that screening can positively influence health behavior changes beyond just disease detection.  

Radiation Exposure: Is it Safe?

Although LDCT involves less radiation exposure than general CT, there can be concerns about frequent radiation exposure for high-risk individuals who need annual screenings. Due to this radiation exposure risk, LDCT is not recommended for everyone but is advisable to be performed selectively on individuals with a high risk of lung cancer. This indicates that the criteria for selecting national screening participants reflect not only cost-effectiveness but also ethical and scientific considerations aimed at minimizing potential harm. In other words, 'who and how often' to screen is a very important decision.  

Therefore, if considering LDCT screening, it is crucial to consult thoroughly with a medical professional to fully understand your individual lung cancer risk, as well as the benefits and risks of the screening. This discussion is an important part of patient-centered care, supporting patients in actively participating in their health management and making informed choices. For children, who are more sensitive to radiation, efforts should be made to minimize even small amounts of exposure.  
 

Comparison of Low-Dose CT (LDCT) vs. Chest X-ray Examination

Low-dose chest CT (LDCT) is the most trusted examination method for lung cancer screening, with proven effectiveness in early detection and mortality reduction. Beyond being a mere diagnostic technology, LDCT has become a tool that produces tangible public health outcomes, such as increasing the possibility of early treatment and even encouraging health behavior changes like smoking cessation.

While limitations such as radiation exposure exist, the risks can be minimized through subject selection based on medical criteria and regular monitoring. What is important is to recognize if you belong to a high-risk group and, after sufficient consultation with a medical professional, undergo the necessary screening at the appropriate time.

Lung cancer is a disease where early detection determines survival rates. Please remember that LDCT is the most effective means to guide you safely and precisely through that first step.