Computed tomography – CT

The CT system was invented by Godfrey Newbold Hounsfield in 1967, and it was publicly announced in 1972. Allan McLeod Cormack of Tufts University independently invented the same process and they shared a Nobel Prize in medicine in 1979. The original 1971 prototype took a little over five minutes for one scan. The images from these scans took 2.5 hours to be processed by algebraic reconstruction techniques on a large computer. Nowadays the whole examination will take only a few minutes.
In a CT machine images are generated using an X-ray source that rotates around the patient. X-ray sensors are positioned on the opposite side of the circle from the X-ray source. Many data scans are progressively taken as the object is gradually passed through the gantry. They are combined together by a mathematical procedure resulting in images of the human body.
During the examination, your child will lie on a table that is part of the CT scanner, which looks like a large doughnut. The table slides into the round opening of the scanner, and the scanner inside the CT scanner moves around your child’s body. The table will move while taking pictures. It is very important to lie still during the test, in young children this may require sedation or anesthesia (this depends on your hospital guidelines for CT scanning of children). During the test, your child may be alone in the scanning room. However, the technologist will watch your child through a window, and you will be able to talk to him or her through a speaker.


For some studies contrast material is needed, it will be given in one of two ways, depending on the body area being studied.


•    Contrast material may be given in a vein (IV) in the arm for chest, belly, and pelvic CT scans.

•    Your child may have to drink contrast material for a belly CT.