X-ray
X-ray refers to the process of exposing the body to X-rays and recording the rays for conversion into an image. The CT examination also makes use of the mechanism of X-rays. This is why CT is correctly called “X-ray computed tomography”.
If you mean the conventional simple X-ray in everyday clinical practice, it is also called “conventional X-ray” or “radiography”. A conventional X-ray image without contrast medium is called “native X-ray”. Nowadays, the X-ray image is registered on a photographic film and chemically converted, but can usually also be read on a computer using digital detectors.
Dense structures absorb the X-rays particularly strongly. With the help of this knowledge, the images can be quickly understood. Bones thus cast a shadow on the film and appear whitish, whereas air is black in the X-ray image.
X-rays are used particularly frequently for bone fractures. Since conventional X-rays only provide a two-dimensional image, depending on the fracture, a second image of a different plane must be taken for more precise diagnosis. For example, a bone fracture may not be visible from the front, but it may be visible from the side.
For this purpose, physicians have standardized imaging techniques that are known to them. The main area of application for conventional X-rays is therefore in the diagnosis of bone fractures. However, it is also used to assess the structure of the heart and lungs, mammography, detection of air-filled spaces in the chest or abdominal area or to visualize vessels.
The use of contrast media is recommended for the imaging of vessels.Depending on the way it works in the body, the contrast medium accumulates in the area of the vessel or organ that you want to depict more precisely. For example, arteries, veins, lymph vessels or the urinary tract can be depicted. These areas light up more strongly in the X-ray image and can be identified and assessed more precisely.
In dentistry, X-rays are often taken to detect caries in the interdental spaces or the position of the wisdom teeth. The rays used are harmful to the body. The dose of an X-ray is very low, but it should not be used too often.
With the help of X-ray passes, patients can more consciously check the number of radiation exposures. Frequent exposure to radiation increases the risk of developing cancer by a small percentage. Magnetic resonance imaging is also known as “magnetic resonance imaging”.
The mechanism is different from that of X-rays. The harmful X-rays play no role in MRI. The effects of the magnetic field in MRI have not been fully researched, but it is assumed that they have no health effects on humans.
The image in the MRI is taken with the help of a very strong magnetic field. The patient is inside the tubular tomograph. The extremely strong magnetic field generated causes all atoms in the body to be excited to move.
In doing so, they emit a measurable signal. MRI enables extremely detailed, high-resolution and high-contrast layered images of the body, as does X-ray CT. In MRI, the differentiation of individual organ areas is not made by light and dark areas as in CT, but mainly by the contrast between two foreign structures.
Soft tissue, in particular, is very rich in contrast in MRI. It is also possible to take MRI images with a contrast medium. This makes it easy to identify different types of tissue, such as inflammations or tumors.
The great advantage is that MRI images do not contain harmful ionizing X-rays. They can therefore be repeated without hesitation and without having to take health risks. The high soft tissue contrast also offers advantages in diagnostics, for example of ligaments, cartilage, tumors, fatty or muscle tissue.
However, a conventional MRI examination takes between 20 and 30 minutes, which is why the images are quickly blurred by movements of the patient or organs. New techniques, however, promise to make it possible in the future to produce real-time images, for example when examining the heart. Unfortunately, the strong magnetic field during imaging also means that patients with any type of implant, for example artificial joints or pacemakers, are not eligible for MRI imaging.
