History & FunctionIn the X-ray method, the body is x-rayed and imaged on an X-ray image. In computed tomography, the body is transilluminated from many directions and displayed on the computer in three dimensions. Click to enlarge.
The inventors of computer tomography are the Austrian mathematician Johann Radon, the physicist Allan M. Cormack and the electrical engineer Godfrey Hounsfield. The first computer tomograph was commissioned in London in 1972 at Atkinson Morley Hospital. In 2009 alone, about 4.88 million patients in Germany were examined by computed tomography.
Computed tomography is used not only in the medical field, but also in archeology in the study of ancient objects, but also in the study of mummies.
With her, for example, the age of the found in the Alps "Ötzi" was determined. Computer tomography is also used in industry.
In the field of medicine, computed tomography is used by means of spiral technology. Here, the patient is slowly driven through the device while the device is rotating. Computed tomography is used, for example, in the examination of the head. Here, the individual arteries as well as brain areas can be displayed efficiently by contrast media. Usually, the first series of tests is carried out natively - ie without contrast agent -, the second is then carried out after the contrast agent administration. This makes any changes in the tissue even better.
Computed tomography is also used to examine the thorax, the abdomen, the upper abdomen, the entire spine, but in some cases also to examine the limbs. This is especially the case in obese patients. While the patient is in the computer tomograph, the sectional images are processed by an external computer with appropriate software. Also, the staff of the practice or hospital sit in a separate control room, but keep in touch with the patient via a microphone.
If a patient gets problems during computed tomography, for example claustrophobia, he or she can give feedback at any time and then either receive a medication for sedation, ie for immobilization, or the computed tomography is interrupted after consultation with the doctor.
Side effect & dangers
Computed tomography has some advantages over the other imaging techniques, but also a few disadvantages. For example, it is much more radiation intensive than an X-ray examination. In computed tomography, for example, a radiation dose of up to 50 times that of conventional mammography is used. Compared to x-ray of the thorax, the radiation dose of a computed tomography is even up to 575 times higher.
Therefore, one should carefully consider whether to perform a computed tomography. Those suffering from claustrophobia should prefer computer tomography over magnetic resonance imaging. Also obese (ie obese) patients should be examined by means of computed tomography, since the "tube" of the MR tomograph is much narrower compared to the computer tomograph. An advantage of computed tomography is that the sectional images have a much better quality than single radiographs. Compared to magnetic resonance imaging - which works with magnetic fields and not with X-rays - it is much cheaper.
Since the radiation dose is significantly lower with new computed tomography than with old equipment, one should visit a doctor's office or hospital, where computer tomography is one of the standard tests. Here one can assume that the latest devices are used.
Nevertheless, a computer tomography should not be carried out too often, as the radiation dose - for example, coronary computed tomography here - can be up to approximately 14 millisieverts per examination.
An employee of a German nuclear power plant may be exposed to a radiation dose of 20 millisievert per year. This comparison should be kept in mind before undergoing computed tomography. However, if computed tomography is considered medically necessary after consultation with the physician, one should not dispense with it. The radiation dose also breaks down relatively quickly. Nevertheless, the risk of cancer is higher after computed tomography.