6.1 Computed tomography
6.2 Electroencephalography
6.3 Evoked potentials (EP) of the brain
6.4 Doppler ultrasound (USDG)
Control questions Situational tasks
6.1. Computed tomography
Tomography (tomos, the Greek for section, grapho, write,) is a method of layer-by-layer study of the structure and function of human organs and tissues. The founder of tomography in medicine is the great Russian surgeon N.I. Pirogov, who developed a new science called topographic anatomy in the mid-19th century using the method of layer-by-layer study in three projections of the organs of frozen corpses. Modern tomography, as a non-invasive method of research, began its development in the mid-20th century from X-ray machines with a tomography attachment. Modern tomography obtaining an image of human body sections using complex devices (tomographs) as a result of interaction of three elements: a radiation source, detectors of its reception and the object itself (while two of them move while the third is motionless). The image is constructed using a computer. Depending on the radiation source (X-ray tube, protons of hydrogen nuclei in a magnetic field, administered radioactive isotopes, etc.), several types of computed tomography are distinguished: X-ray, magnetic resonance, positron emission, etc.
X-ray computed tomography (CT). The method is based on transmitting x-ray radiation through the human body and fixing the degree of its attenuation to
various structures of the studied section of the body by using hypersensitive detectors (layer thickness of about 1 mm). For a quantitative assessment of the degree of attenuation, the Hounsfield scale is used, in which water attenuation is taken as 0 units, a lower degree of attenuation is expressed in negative units (for example, fat - 120 units, air - 1000 units), a higher degree of attenuation in comparison with water positive units (e.g., soft tissue +40 units, bones +400 units). The degree of attenuation (radiodensity) is displayed on a computer monitor in various shades of gray, whose amount depending on the tomograph can be from several hundred to a thousand. Tomography is performed using software packages (both a standard package and specialized programs), which makes the study more focused and reduces radiation exposure. Thus, X-ray computed tomography yields a layered image of various body structures, which allows us to determine their shape and size, as well as pathological processes accompanied by a change in radiodensity. Cerebral tissues with excessive density are hematomas, calcification sites, meningeal tumors, denser areas of ischemia, cysts, glial, and meta-static tumors.