CT scan

CT scan also known as CAT scan stands for computer tomography, where the complete picture of the body is taken using Xrays and computer is used to see various parts, even slices of the parts. This helps in detecting some of the difficult growth or changes occurring in the body which is not visible to naked eye. It is usually performed to detect tumours in the internal organ like intestine, lungs and to know the vessel wall conditions like the renal artery.
The picture produced by CAT scan is referred to as tomography, which is usually taken by making the patients lie on the couch and sending the couch inside the machine through a hole which is located in front of the machine.
Working mechanism
CT scan works basically like an X-ray machine, the difference being X-ray machine sends one beam of radiation which passes through the human body and the radiograph is obtained. In CT scan this is done at a huge proportion the beams are sent through the narrow beams, the beams are not emitted once but detailed succession beams are emitted giving a detailed image which is superior to basic X-ray.
The CAT scan machine has a built in X-ray detector which analysis many variety of density of the picture, this makes it possible to differentiate soft tissue and solid organs, which is unlikely to do in a normal X-ray. This information is then sent to the computer, where the program allows the computer to see the picture in many section allowing the doctor to look into the organs and soft tissue to see any abnormality.
Like contrast X-rays where a dye is used, contrast CT scan is possible; this helps to further differentiate the organs fairly easily. It is also useful in detecting the occlusion of the vessels or intestinal tract. For example for examination of the abdominal cavity the barium dye is used, for examination of vascular system a dye is injected into the blood stream.
The new advances in CAT includes spiral scan where the beams are emitted in spiral pathway, this allows a better picture which sharp differentiating characters between the images.
Procedure:
The machine runs on motor. This couch moves in and out of the machine allowing the pictures of the body to be taken. The doctor might decide to perform only a part of the body to be scanned or a whole body CT scan depending on the medical condition.
Before the scan all the jewellery and the clothing is removed and a hospital gown is given to patient. If the pt is very apprehensive then a sedative is given. For children they are usually sedated before the CT.
In a whole body scan, the patient lies on the couch and is secured to it, the radiographer steps out of the room before starting the procedure but he will be able to talk through the intercom regularly. The couch moves few inches inside the machine and starts taking the picture, in order to avoid any blur the patient will be advised not to move, but can breathe normally.