Tracheostomy, CT scan. Coloured 3-D computed tomography (CT) scan of a cancer patient with a tracheostomy tube inserted into his windpipe (trachea). This procedure is used when injury or disease, such as a mouth or throat tumour, causes difficulty breathing. This image was produced using a multi-slice CT scanner, which uses a thin X-ray beam to scan around the patient to collect data from different angles and create 'slices' of the body. OsiriX medical imaging software was used to reconstruct the data slices into coloured 3-D images which can be animated.