Radiography is one of the main methods of radiological research, consists in obtaining the sensitive layer of constant negative image of the object. On the one hand, radiography is, along with fluoroscopy (see) the primary method of roentgenologic examination and relates to the competence of the doctor-radiologist, i.e. is the method purely medical research, contributing to the diagnosis. On the other hand, radiography is a technical process of obtaining x-rays and is in the competence of persons engaged in this process.
The technique of x-rays, along with the doctor-radiologist should own and his assistant - roentgenologist. When properly organized process x-ray doctor-radiologist is acting as a Manager and consultant. The main work of x-ray performs roentgenologist who should know laying and installation of patients for radiography all areas of the body. Only fluent technique for obtaining x-rays can be used to select the exposure and other technical conditions, and then to ensure the correct processing and registration of x-rays (see), making it quite suitable for x-ray diagnostics.
The most important criterion for assessing the degree of qualification of roentgenologist is its ability to standardize the process radiography enough to provide identical to x-rays at repeated x-rays of the same objects of study and receive a standard comparable x-ray paired anatomic formations of the right and left side of the body. The latter is necessary because in some cases only radiographically the same and also the flat correct image to the same parts of the skeleton of the right and left sides of the body can serve as a basis for establishing unilateral pathological changes.
As for getting technically identical to x-rays at repeated shots during a dynamic observation of the course of pathological processes, this requirement is primarily due to the fact that a series of x-rays produced during a long period of time, allows to objectively judge the nature of the flow of a number of chronic diseases, such as pneumosclerosis, emphysema, tuberculosis, saying disease stomach and duodenal ulcers, rickets, tuberculosis and other chronic lesions of bones. This feature of the standard x-ray can be used not only for the purpose of x-ray diagnostics in the narrow sense, but also as a method of monitoring the effectiveness of treatment.
Fig. 1. Accessories for patient positioning in radiography.
Standardization of the process x-ray in order to obtain technically homogeneous high-quality radiographs achieved: 1) standardize the style and facilities of patients with x-rays (see x-Ray examination, basic installation and setup in radiography); 2) the right choice rentgenotechnika conditions at the pictures, especially the repeated; 3) standardization of the process of photographic processing x-rays. To standardize the style and facilities of patients in radiography, tripods modern x-ray machines supplied with corresponding linear measuring scales, angle-finders is considered and the centralizers, as well as fittings for fixing of patients during radiography. Along with this, it is advisable to have a set of sacks with sand with different dimensions and weight, semi-rigid pelota of loofah or wool, as well as accessories in the form of a set consisting of squares, benches and tables (Fig. 1), which provides more comfortable laying sick and tight fit of the investigated body parts to the plane of the cartridge. In radiography preschool children and seriously ill patients should not use hard-devices for fixing. In these cases, it is preferable to use the support staff with the observance of safety measures and antiradiation protection. To reduce the impact of voluntary and involuntary movements of the subject and staff, retaining patients on image quality (Unsharp images) should fit x-ray equipment for a forced position of patients and apply the shortest possible shutter speed.
Although radiation load images is much less than at the x-raying, you radiography adults and especially children to carefully follow radioprotective measures of protection through the use of tubes, aluminum filters that absorb couch radiation, lead diaphragms, the bounding box of exposure, and the maximum use of protective equipment from the scattered x-ray radiation (lead, lead-impregnated rubber). Special attention should be paid to the protection area of the gonads (sex glands).
The correct choice of technical conditions in radiography greatly facilitated by the fact that the modern x-ray machines (see) with instructions containing a detailed table of the exhibitions for all body parts, designed for a person of average weight, height and build. However, in practice often, for various reasons, there is a need to change some scenes. In this regard, roentgenologist should know the basic laws affecting the formation of technical parameters of x-ray under different conditions of roentgenochemical.
Radiography is one of the main methods of radiological research, which by means of x-rays on the photosensitive film after its photographic processing the image of the object.
There are normal and special x-rays. Special x-rays are: tomography (see), sighted, in particular tangential images, so-called contact R., teleroentgenography, hard or superexponentially photos, Polygraphy, rentgenonegativee, rentgenografii (see), dry R. - xerography.
Plain x-rays are produced in two standard projections (see X-ray). R. only in these two projections (Fig. 1) provides the General spatial representation about object, but not enough displays the individual details of the status of all bodies and surfaces of the object (Fig. 2).
For a more detailed study of any portion of the study object, sometimes produce special aligned (targeted) images. For this, the interest portion of the study object is determined during the preliminary screening (see X-rays) in the center of the screen and then shoots on film small size. The value of these pictures is that with reduction of the irradiated field resolution radiographs improving. If in the production aligned snapshot of the Central beam of x-rays is directed on to the message to the contour of the studied part of the object, you get aligned tangential images (Fig. 3 and 4).
In cases when you need to be particularly clear picture of the parts of the object, adjacent to the tape, and remove the image tissues, preventing identification of the examined organ, produce so-called contact x-rays by the maximum approximation (up to direct contact) x-ray tube to the surface of the object.
In order to eliminate the projection of the increase of the investigated object and getting on the x-ray image in full size used teleroentgenography, in which the distance between the focus and the subject is brought up to 2 meters
To detect the x-ray more details produce hard shots, increasing the voltage of the tube up to 120-125 square
In the study of the motor function of some organs used Polygraphy, when for a short period of time at one film consistently produce multiple images (usually 3), and rentgenografii.
Method of dry radiography (xerography is a fundamentally new that does not require the processing, the way radiography, when image receive special plates, covered with metal powder, sensitive to the effects of x-rays.
Radiography is of great importance the number of x-ray radiation which is equal to the product of the strength of the secondary current at time of exposure and is measured in milliamperemeter. Successful implementation of the x-ray depends on the correct choice of the exposition, which is determined taking into account the nature of the object (structure, thickness and density of its tissues), the voltage on the x-ray tube focal length, but also on the quality of intensifying screens and x-ray films, temperature and activity of the developer and from the time of the manifestation.
Radiography is an examination method, not indifferent to the patient. Therefore, when carrying out radiography should strive for maximum reduction of radiation exposure to the patient.
The number of x-ray radiation falling on the photosensitive layer of the film, is directly proportional to the exposure time and inversely proportional to the square of the distance of the focus of the object.
Radiation exposure to the patient is reduced by increasing the voltage of the tube and a corresponding reduction of the exposition. Increase the voltage by 10 kV allows the reduction of exposure in approximately two times.
The use of amplifying (IgM) screens can reduce the exposure time is 10-20 times, which is especially needed in the study of movable objects (lungs, heart, stomach, esophagus, duodenum). However, the application of intensifying screens reduces acuity (sharpness) x-ray image. Therefore, to obtain structural images of small objects (nasal bones, the teeth, phalanges) x-rays are produced without intensifying screens.
Mistakes in selection of technical conditions in radiography cause poor quality radiographs. Therefore, it is necessary to keep records of the shooting conditions, focusing on those in which manages to get x-rays of good quality. Seeking re-R. improve the quality radiographs, it is not necessary to modify all the technical conditions rubles With the overexposure or underexposure to be improved results radiography primarily a corresponding change the exposure time.
When photolaboratory processing radiographs should strictly abide by the conditions recommended by the factory, producing the materials.
The usual time of manifestation at the optimum temperature 18-20 degree Celsius is 5-6 minutes Each degree of deviation from this temperature requires lengthening (or reduction) of the period of manifestation of 0.5 minutes Activity of the developer and its quantity as you use them gradually.
To maintain the stability of the developer enjoy a refreshing solution which add to the developer as its decline.
Radiography in standard projections normally produced by rentgenologists. However, for maximum diagnostic results all kinds R. must be performed under the guidance and direct participation of the doctor-radiologist.
Fig. 1. Scheme of chest radiography in standard projections: 1 - straight; 2 - side.
Fig. 2. Radiography in two projections (displays the status of the surface of an object only in the areas of passing beam on a tangent).
Fig. 3. The tangential projection of metal label (coin), located in a bar a little higher subtle fracture VI ribs.
Fig. 4. The scheme aligned x-rays: the dashed line denotes the position of the ruined edge of the alveolar process of the cancer (regional defect).