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A CT (computed tomography) scan takes many X-ray pictures from different angles and builds them into detailed cross-sections — like looking at the chest slice by slice. It shows far more than a plain X-ray, so it's used when a clearer answer is needed: to look closely at the lungs, airways and blood vessels. It uses more radiation than an X-ray, so it's chosen when that extra detail will change your care.
Why it's done & the main types
| Type of CT | What it's for |
|---|---|
| Standard chest CT | A detailed look at the lungs and chest — infections, masses, fluid, general assessment. |
| High-resolution CT (HRCT) | Very fine lung detail — bronchiectasis, interstitial lung disease and fibrosis, emphysema. |
| CT pulmonary angiogram (CTPA) | Uses contrast dye to look for a pulmonary embolism (clot on the lung). |
| Low-dose CT | Lung-cancer screening and nodule follow-up, at a reduced radiation dose.1 |
What it can show
Because of its detail, CT can reveal detail an X-ray cannot: small lung nodules, the pattern and extent of bronchiectasis or lung fibrosis, the distribution of emphysema, blood clots in the lung arteries, enlarged lymph nodes, and the precise size and position of any mass.
What to expect
You lie on a table that slides through a large ring (not an enclosed tunnel like an MRI). It's quick — often under a minute of scanning — and painless. You'll be asked to hold your breath briefly so the images are sharp. Some scans use a contrast dye given through a small cannula in the arm, which can cause a brief warm flush; tell staff about allergies, kidney problems or if you might be pregnant.
Radiation
A chest CT uses more radiation than a plain chest X-ray, so it's reserved for when the added detail is worth it. Your team weighs this up, and low-dose protocols are used where possible.2
How physiotherapists use it
CT findings help physiotherapists understand the pattern and distribution of lung disease — for example, which lobes are affected by bronchiectasis — so airway-clearance and positioning can be targeted precisely. It also confirms diagnoses that shape a rehabilitation plan. As always, imaging is read with the report and combined with hands-on assessment. See Chest X-ray and Principles of Airway Clearance.
References & evidence base
- Cancer Council Australia. National Lung Cancer Screening Program. Sydney: Cancer Council Australia, 2025. Available at: cancer.org.au
- Royal Australian and New Zealand College of Radiologists. Inside Radiology: computed tomography (CT). Sydney: RANZCR, 2024. Available at: insideradiology.com.au
References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.
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