MODEL RELEASED. CT scanning. Radiologist preparing a male patient for a head scan in a CT (computed tomography) scanner. The laser lines are used to align the scanner. CT scanning is a diagnostic technique in which numerous short bursts of low dose X-rays are passed through the body at different angles. A computer then produces a cross-sectional image of the tissues. A CT scan provides more detail than a normal X-ray, yet it reduces the patient's exposure to harmful radiation. CT scans are used to diagnose and assess strokes, along with tumours, haemorrhages and abscesses.