Artifact (from lat. ars, artis - art, factum - made) - 1) in histological techniques such as artificial structures found in histological preparation when using the microscope; 2) in the x - foreign shadows on x-rays, caused by technical errors.
Histological artifacts often are formed under the action of retaining fluids that cause coagulation and precipitation of colloids cytoplasm and nucleus cells, and sometimes their dissolution and changing shape. Artifacts can occur when pouring, cutting, coloring and conclusion of drugs. Artifacts are easily formed when electron microscope microscopy of tissue under the influence of the changed composition of the medium, temperature, mechanical pressure and other factors. It is especially important to identify artifacts in ultrathin sections electron microscopy. The complexity of manufacturing ultra-thin slices, study them in a vacuum and electron bombardment create preconditions for the emergence A.
Artifacts when histochemical studies associated with posthumous diffusion identify the substance in structure, in fact, it does not contain. In gistiotitarnaya A. largely depend on the conditions of exposure and processing of the region, combined with histological cut.
X-ray artifacts can be codified primarily as highlights on x-ray and lots more intensive blackening compared to their surroundings. Morphologically they are presented, alopecia, linear, stripped, circle, diffuse shadows and shadows indefinite form. Some of the artifacts clearly accidental origin (for example, scratches), reducing the quality of the x-ray does not significantly interfere with diagnostic use. Much more important are those of A., which in appearance similar to the manifestation of a number of pathological processes and can therefore be a source of diagnostic errors.
Some artifacts arise in the process of factory production of films. They in most cases are easily recognized even by non-specialists. The emergence of foreign shadows may also due to improper storage of x-ray films (for example, in conditions of high humidity or in the scope of penetrating radiation), careless handling with them. There may be so-called friction veil, i.e., the blackening of the film at its manifestation in the areas of mechanical effects on light-sensitive emulsion, or the total veiling of the film under the action of penetrating radiation or daylight and artificial light that on the x-ray may not always be easily taken into account.
The most important in the diagnostic are defects in images, resulting in the radiography and in photographic processing films: strange shadows, for example from clothing, bandages, hair rolled into a bun or woven into a braid, some medicinal substances etc.
The artifacts include total or partial overexposing films, which is often a consequence of the lack of neaktivnosti photolaboratory lanterns and fault cassettes, transmits light. Under normal x-ray with intensifying screens available on some screens defects are passed on radiographs shadows, similar with metal fragments (which is particularly important in ophthalmic practice), with the stones, various structural changes of the substrate (such as fractures of the bones), and so on, Sometimes unwanted shadows appear when errors manifestations, fixation and drying films, creating similarity with destructive lesions, lesions seals in the bone substance or a line break. Some artifacts similar to the paintings of tissue calcification. Examples given are not limited educational opportunities, foreign shadows on radiographs. At the same time should not be taken wrongly A. pathological shadows.