Low-Dose CT for Lung Screening: Who Qualifies and What to Expect

Every year, over 130,000 people in the U.S. die from lung cancer. Most are diagnosed too late-when treatment is harder, less effective, and far more expensive. But there’s a simple test that can catch it early, when it’s still curable: low-dose CT for lung screening. It’s not magic. It’s science. And it’s available to millions of people who don’t even know they qualify.

Who Should Get Screened?

If you’re between 50 and 80 years old and have smoked at least 20 pack-years, you’re likely eligible. A pack-year means smoking one pack a day for a year. So if you smoked a pack a day for 20 years, or two packs a day for 10 years, you hit that threshold. Even if you quit smoking, you still qualify if you stopped within the last 15 years.

This isn’t just a guess. It’s based on massive studies like the National Lung Screening Trial (NLST), which tracked over 53,000 people. Those who got annual low-dose CT scans had 20% fewer lung cancer deaths than those who got chest X-rays. That’s not a small win-it’s life-changing.

Some guidelines, like those from the American Cancer Society and the National Comprehensive Cancer Network, go even further. They suggest screening for people who quit more than 15 years ago if they have other risk factors-like a family history of lung cancer, exposure to asbestos or radon, or a history of lung disease like emphysema or pulmonary fibrosis.

But here’s the catch: only about 23% of eligible people in the U.S. are actually getting screened. Why? Many don’t know they qualify. Others are scared of false alarms. Some can’t get to a clinic-especially in rural areas, where the nearest screening center might be 30 miles away.

What Happens During the Scan?

The test itself takes less than 10 seconds. You lie on a table, raise your arms, and hold your breath while the machine spins around you. No needles. No fasting. No prep. You don’t even need to change clothes.

The machine uses a fraction of the radiation of a regular CT scan-about 1.2 millisieverts (mSv). That’s roughly the same amount of radiation you’d get from natural sources in four months. For comparison, a standard chest CT is about 7 mSv. The low-dose version is designed to find small nodules without exposing you to unnecessary radiation.

The images are analyzed by radiologists trained in lung screening. They look for nodules-small spots in the lungs. If a nodule is 4 millimeters or larger, it’s considered positive and needs follow-up. Most of these aren’t cancer. In fact, 96% of positive scans turn out to be harmless.

What Do the Results Mean?

Your result will fall into one of three categories:

• Negative: No nodules found, or only tiny, harmless ones. You’ll be asked to return in a year.
• Positive: A nodule 4 mm or larger is seen. This doesn’t mean cancer. It means you need more tests-usually another CT scan in 3 to 6 months to see if the nodule grows.
• Indeterminate: Something unclear shows up. You might need a PET scan, biopsy, or longer follow-up.

The biggest fear? False positives. And yes, they happen. In the first year of screening, about 24% of people get a positive result. But by the third year, that drops to under 10%. Most of these are just scars from old infections, inflammation, or even dust in the lungs.

Still, waiting for results can be brutal. One patient from Ohio told her story on the American Lung Association’s website: “I spent six weeks thinking I was dying. Then they said it was nothing. But I’ll never forget those days.”

What Happens If Cancer Is Found?

If a nodule grows or looks suspicious, you’ll be referred to a lung specialist. Most screen-detected cancers are caught at Stage I-when they’re still small and haven’t spread. At this stage, surgery alone can cure over 80% of patients.

Today, most surgeries are done using video-assisted thoracoscopic surgery (VATS), which uses small incisions and a camera. Patients go home in 2-3 days instead of a week. Recovery is faster. Pain is less. And survival rates are dramatically higher than if the cancer had been found later.

The NLST found that 71% of cancers caught by LDCT were Stage I. In the group that got chest X-rays, only 49% were caught that early.

Are There Risks?

Yes. But they’re small compared to the benefits.

The biggest risk is radiation-but even that’s minimal. Studies estimate that for every 1,000 people screened annually for 10 years, you might cause one extra cancer death from radiation. But you prevent 15 lung cancer deaths. That’s a net gain of 14 lives.

Another risk is overdiagnosis-finding a slow-growing cancer that might never have caused harm. But this is rare in lung cancer. Most screen-detected tumors grow fast enough to be dangerous if left alone.

The real challenge? Access. Only 18.5% of eligible people in rural areas get screened. Urban areas are better, but still below 35%. And Black Americans-who have higher lung cancer rates-are screened at 28% lower rates than White Americans.

What’s Next?

The U.S. government is considering expanding eligibility even further. Right now, you must have quit smoking within the last 15 years. But research shows lung cancer risk stays high for 25 years or more after quitting. One study found that 34% of lung cancers occur in people who quit over 15 years ago.

New tools are helping too. Artificial intelligence can now analyze scans faster and more accurately. One FDA-approved AI tool, LungPoint®, reduces radiologist workload by 30% while keeping detection rates above 97%.

Blood tests are also coming. The EarlyCDT-Lung test looks for antibodies that signal early cancer. In 2023 trials, it had a 94% negative predictive value-meaning if it says no cancer, you’re very likely safe.

What Should You Do?

If you think you qualify, talk to your doctor. Don’t wait for them to bring it up. Bring it up yourself. Say: “I’m 55, smoked a pack a day for 25 years, and quit five years ago. Should I get screened?”

Ask if your provider is part of the ACR Lung Cancer Screening Registry. That means they follow national standards for quality, radiation safety, and follow-up.

If you’re on Medicare, the test is free. No copay. No deductible. As long as you meet the criteria and get a referral from your doctor.

If you’re uninsured, many community health centers and hospitals offer low-cost or sliding-scale screenings. Call your local American Lung Association office-they can help you find one.

Real Stories, Real Outcomes

Mary Johnson, 58, from Ohio, had her first LDCT scan in 2022. She’d smoked for 30 years, quit 12 years ago. The scan found a 6mm nodule. Follow-up confirmed Stage I adenocarcinoma. She had surgery. No chemo. No radiation. Today, she’s cancer-free.

James Wilson, 62, from Texas, also had a positive scan. His nodule turned out to be benign. But he spent three months in anxiety, paid $450 out of pocket for extra tests, and still wakes up wondering if it’s back.

These aren’t outliers. They’re common. And they show why screening works-but also why it needs to be done right.

Final Thoughts

Low-dose CT screening isn’t perfect. But it’s the best tool we have to stop lung cancer before it kills. It’s not about fear. It’s about control. About knowing. About catching it early enough to beat it.

If you’re eligible, don’t wait. Talk to your doctor. Get screened. One scan could give you 10 more years. Or 20. Or more.

Next Steps

If you’re eligible, don’t wait. Make a list: your age, how long you smoked, when you quit. Then call your doctor. Say: “I think I qualify for lung screening. Can we talk about it?”

If you’re not eligible yet but still smoke-quit. It’s the single best thing you can do. And if you’re past 80 or quit more than 15 years ago without other risks, talk to your doctor about whether screening still makes sense for you.

This isn’t about fear. It’s about knowing. And knowing gives you power.