CT - Scan
About Computerised Tomography (CT)?
A CT scan (computerised tomography) also known as CAT scan (computed axial tomography) is a specialised x-ray test. It can give quite clear pictures of the inside of your body. In particular, it can give good pictures of 'soft' tissues of the body which do not show on ordinary x-ray pictures.
A CT scan (computerised tomography) also known as CAT scan (computed axial tomography ) is one of several diagnostic procedures that helps give doctors a better idea of what is going on inside your body. Unlike an X-ray, which only takes one image of your body, a CT scan takes a series of images. Each image is a cross section of a portion of your body, and when all the cross sections are put together with the help of the computer, they provide a much more in-depth look.
The advantage to having a CT scan done rather than an X-ray, is that a CT can "see" more features that would not be visible on a standard X-ray. For example, organs and tissues show up more readily on a CT scan. Additionally, a CT scan exposes the patient to less radiation than an X-ray, thereby making it a safer procedure. This is especially important since many cystic fibrosis patients will undergo dozens of X-rays in the course of a lifetime of treatment.
The CT scanner looks like a giant thick ring. Within the wall of the scanner there is an x-ray source. Opposite the x-ray source, on the other side of the 'ring', is an x-ray detector. You lie on a couch which slides into the centre of the 'ring' until the part of the body to be scanned is between the x-ray source and detector. The x-ray machine and x-ray detector both rotate around your body, always being opposite each other. As they rotate around, the x-ray machine emits thin beams of x-rays through your body which are detected by the x-ray detector.
The detectors detect the strength of the x-ray beam that has passed through the body. The more dense the tissue, the less x-rays pass through. The x-ray detectors feed this information into a computer. Different types of tissue with different densities show up as a picture on the computer monitor as different colours or shades of grey. So, in effect a picture is created by the computer of a 'slice' (cross section) of a thin section of your body.
The couch is then moved slightly further through the 'ring' to get a picture of the next section of your body. So, several cross sectional pictures or 'slices' of the part of your body being investigated are made by the computer. Newer scanners can even produce 3-dimentional pictures from the data received from the various 'slices' of body.
