Early detection saves lives—and that’s especially true when it comes to lung cancer. A low-dose CT (LDCT) scan is a powerful tool that can find lung cancer in its earliest, most treatable stages. But not everyone needs this screening. One of the main factors used to determine eligibility is your smoking history, measured in what’s called “pack-years.”

Here’s how to calculate your pack-year history and find out if you might qualify for a lung screening.

What Is a Pack-Year?

A pack-year is a way to measure how much and how long a person has smoked. It combines the number of packs of cigarettes you smoke per day with the number of years you’ve smoked.

The formula is simple:

Pack-years = (Packs smoked per day) × (Number of years smoked)

Example Calculations

Let’s look at a few examples:

• Example 1: You smoked 1 pack per day for 20 years.
  → 1 × 20 = 20 pack-years
• Example 2: You smoked 2 packs per day for 10 years.
  → 2 × 10 = 20 pack-years
• Example 3: You smoked half a pack per day for 40 years.
  → 0.5 × 40 = 20 pack-years

In each example, the total is 20 pack-years — which is an important threshold for lung screening eligibility.

Who Qualifies for a Low-Dose Lung Screening CT Scan?

According to the U.S. Preventive Services Task Force (USPSTF), you may qualify for an annual low-dose CT scan if you meet all of the following:

• You are between 50 and 77 years old, and
• You have a 20 pack-year or greater smoking history, and
• You currently smoke or have quit within the past 15 years

If you meet these criteria, talk to your healthcare provider about scheduling a low-dose CT lung screening. The scan is quick, painless, and can significantly improve survival rates by finding lung cancer before symptoms develop.

Why It Matters

Lung cancer often doesn’t cause symptoms until it’s in an advanced stage. LDCT screening can detect small nodules or abnormalities long before they become serious. Studies show that LDCT screening can reduce the risk of dying from lung cancer in high-risk patients by catching it early.

Take the Next Step

If you’re unsure about your smoking history or whether you qualify for screening, your provider can help you calculate your pack-years and discuss your options.

At Eastern Radiologists, our team offers advanced low-dose CT lung screening designed with your safety and peace of mind as our top priority. We are an ACR Designated Lung Cancer Screening Center, meeting specific criteria that demonstrates our commitment to the highest standard of lung cancer imaging.