Patient guide · 5 min read
Lung cancer screening CT, what to expect from your low-dose CT scan.
A practical patient guide to the low-dose CT scan used for lung cancer screening — what to expect on the day, radiation dose in context, what the radiologist looks for and what happens if the scan is positive.
Why this scan matters
- 01
A scan, not a shortcut
A low-dose CT is the only imaging test proven to reduce lung-cancer mortality in eligible smokers and ex-smokers.
- 02
Ten seconds on the table
The actual acquisition takes about ten seconds — total appointment time is around fifteen minutes.
- 03
Read against Lung-RADS
A consultant thoracic radiologist grades every scan against the ACR Lung-RADS system, so the next step is always defined.
Key facts
The essentials of a lung cancer screening CT.
Six facts that describe the test — what it is, the radiation dose in real-world terms, how long it takes, and how it’s reported.
In short
A 10-second chest scan at ~1.5 mSv, reported against Lung-RADS.
| Fact | Detail |
|---|---|
| What it is | Low-dose CT of the chest for lung cancer screening. |
| Radiation dose | ~1.5 mSv (about six months of UK background radiation). |
| Scan time | 10 seconds on the table, one breath-hold. |
| Preparation | None. No fasting, no IV contrast. |
| AI-assisted read | AI-based nodule detection supports the radiologist. |
| Reporting standard | Structured reporting using ACR Lung-RADS categories. |
On the day
From eligibility check to report — what happens, in order.
Seven steps take you from the invitation letter to a defined next-step recommendation.
Phase 1 · Before
Eligibility and appointment
Phase 2 · On the day
~15 minutes at the clinic
Phase 3 · After
Reporting and follow-up
- 01
Before
Eligibility check
Age, smoking history and family history reviewed against the NHS Targeted Lung Health Check criteria.
- 02
Before
Attend appointment
Arrive fifteen minutes early, wearing a top with no metal fastenings if possible.
- 03
Before
No preparation required
Eat, drink and take medication as normal. No fasting and no IV contrast are needed.
- 04
On the day
Change into a gown
You’ll change into a hospital gown and remove any metal from the chest area.
- 05
On the day
Scan takes 10 seconds
You lie on your back, arms above your head, and hold your breath for a single ten-second acquisition.
- 06
After
Radiologist reports
A consultant thoracic radiologist reports the scan against ACR Lung-RADS, usually within 48 hours.
- 07
After
Structured follow-up plan
Every scan produces a defined next step — reassurance, interval CT, or an onward diagnostic pathway.
What it shows
What the radiologist looks for.
A screening CT reports on the target finding — a suspicious nodule — and a defined set of clinically important incidentals.
-
Solid pulmonary nodule
A well-defined solid lesion — the most common screening finding, most are benign.
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Sub-solid nodule (ground-glass)
A hazy density that can indicate slow-growing adenocarcinoma spectrum lesions.
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Suspicious mass
A larger, ill-defined or spiculated lesion needing urgent characterisation.
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Emphysema (LAA %)
Quantitative low-attenuation area percentage — an incidental measure of emphysema burden.
-
Coronary calcium (incidental)
Visible coronary artery calcification informs cardiovascular risk.
-
Aortic aneurysm (incidental)
Thoracic aortic diameter is measured and flagged if enlarged.
-
Interstitial lung disease
Reticulation, honeycombing or ground-glass patterns suggesting fibrosis.
-
Red flag: Lung-RADS 4B or 4X — urgent 2-week-wait pathway
A category 4B or 4X finding triggers an immediate urgent-suspected-cancer referral.
Next steps
What happens after the scan.
Every Lung-RADS category has a defined next step, from reassurance to a 2-week-wait referral.
-
Reassurance for Lung-RADS 1–2
Negative or benign appearance — return to annual screening.
-
6-month interval CT for Lung-RADS 3
Probably benign — a short-interval repeat CT at six months.
-
3-month CT or PET for Lung-RADS 4A
Suspicious — three-month CT, PET-CT or tissue sampling as appropriate.
-
Immediate biopsy for Lung-RADS 4B/X
Very suspicious — proceed straight to tissue diagnosis via the 2-week-wait pathway.
-
Fleischner-guided nodule surveillance
Incidental nodules outside screening use Fleischner Society follow-up intervals.
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Multi-disciplinary team review
Complex findings are discussed at the thoracic MDT before next steps.
-
Bronchoscopy / EBUS
Endobronchial ultrasound and bronchoscopic biopsy for central lesions or nodal disease.
-
Thoracic surgery pathway
Referral to a thoracic surgeon for wedge resection, lobectomy or VATS as indicated.
Sources
The guidance behind this page.
Clinically reviewed against national programmes and specialist society guidelines.
Peer-reviewed references
The four sources we lean on most.
Red flags
Findings that trigger urgent action.
Nine features on a screening CT that move you onto an accelerated diagnostic pathway.
-
Lung-RADS 4B or 4X
Very suspicious findings — immediate urgent-suspected-cancer referral.
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Nodule growth on interval scan
Documented enlargement between scans upgrades the Lung-RADS category.
-
Cavitating lesion
A thick-walled cavity raises concern for malignancy or infection.
-
Bulky mediastinal disease
Enlarged mediastinal nodes or a mass need urgent characterisation.
-
Pleural effusion with mass
An effusion alongside a lung mass suggests advanced disease.
-
SVC obstruction
Facial swelling, distended neck veins or dilated collaterals — an oncological emergency.
-
Bone metastases on CT
Lytic or sclerotic lesions on the visualised skeleton indicate metastatic disease.
-
Adrenal mass
An adrenal lesion picked up incidentally needs dedicated characterisation.
-
Interstitial pneumonia with hypoxia
A pattern of pneumonitis with low oxygen saturations needs same-day respiratory review.
Reading your report
Every screening CT gets a Lung-RADS score.
The ACR Lung-RADS system converts the radiologist’s findings into a category from 1 to 4X, each tied to a specific management recommendation.
A quiet reminder
A positive Lung-RADS score does not mean cancer — most nodules are benign.
The score defines the next step, not the diagnosis.
- 01 Lung-RADS 1
Negative
No nodules or definitely benign nodules. Return to annual screening.
- 02 Lung-RADS 2
Benign appearance
Nodules with a very low likelihood of cancer. Return to annual screening.
- 03 Lung-RADS 3
Probably benign
Six-month interval CT for surveillance.
- 04 Lung-RADS 4A/B/X
Suspicious → very suspicious
4A: three-month CT or PET. 4B/X: tissue sampling and 2-week-wait referral.
Recognised by major UK insurers
Cover depends on your policy and clinic; we confirm with your insurer before booking.
Frequently asked
Everything we get asked about lung cancer screening CT.
Quick answers on eligibility, radiation, preparation, Lung-RADS and what a positive scan actually means.
-
Who is eligible for lung cancer screening CT?
The NHS Targeted Lung Health Check programme invites people aged 55–74 with a significant smoking history — current smokers or those who’ve quit within the last 15 years. Private access is available for those outside NHS criteria who have concerns.
-
How much radiation is a low-dose CT?
Around 1.5 mSv per scan — roughly six months of natural UK background radiation, and a small fraction of a standard chest CT (~7 mSv).
-
Do I need to fast or have IV contrast?
No. Lung cancer screening CT is performed without any preparation and without intravenous contrast — you can eat, drink and take medications as normal.
-
What is Lung-RADS?
Lung-RADS is the American College of Radiology’s structured reporting system for screening CT. Each scan is graded from 1 (negative) to 4X (very suspicious) with a defined follow-up recommendation for each category.
-
What happens if the scan is positive?
A positive scan doesn’t mean cancer — most nodules are benign. Depending on the Lung-RADS category, you’ll be offered a short-interval CT, PET-CT, biopsy or a 2-week-wait referral to a thoracic MDT.
-
How is this different from a chest X-ray?
A chest X-ray cannot reliably detect early-stage lung cancer. Only low-dose CT has been shown in randomised trials to reduce lung cancer mortality in high-risk populations.
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In practice, in London
How lung cancer screening CT tends to unfold when you go private
With lung cancer screening CT, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. Waiting lists on the NHS for lung cancer screening CT vary widely by borough and by how the GP letter reads. Privately in London, we can normally offer a slot inside the same week, sometimes within 48 hours if there’s a cancellation. The difference isn’t clinical quality — the consultants are frequently the same faces you’d see on the NHS — it’s the calendar.
A private lung cancer screening CT pathway in London usually looks like this: an initial consultation, any diagnostics booked at a nearby facility (most within Zone 1 or 2), and a written report sent to you and your GP within a few days. The consultants we work with hold NHS posts alongside their private lists, which keeps the standards consistent across both settings. For lung cancer screening CT specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
Fit matters more than people expect. For lung cancer screening CT, the right consultant depends on what you actually need — a second opinion, a definitive diagnosis, a bridge into treatment, or reassurance that nothing’s being missed. We match on that, not on who has the biggest brochure. If a test isn’t the right next step, we’ll say so before you book anything.