Heart and lungs, 3D-CT scan. Coloured 3-D computed tomography (CT) scan of the heart (middle centre) and lungs, showing the small airways (bronchioles) of the lungs. The rib cage surrounds the lungs. This image was produced using a multi-slice CT scanner, which uses a thin X-ray beam to scan around the patient collecting data from different angles to create 'slices' of the body.