Bases of x-ray scialogy

At roentgenologic evaluation by the article of study there is the shadow image, which because of optical and geometrical features appears in an unusual spatial prospect and not always represents a veritable form, size and position of the proper object. Therefore for correct interpretation of roentgenologic picture understanding of basic laws of scialogy is needed (study about shadow formation). In the basis of analysis of x-ray image the study of formative it shades is fixed, estimation of basic scialogy properties: quantities, size, form, intensity, structure, contours and movement.

Shades of different pathological educations can meet or be laid on on each other and the same distorted the picture of veritable their quantity and closeness (see the fig. 10.5.). Consequently, for determination of veritable quantity of educations it is necessary to conduct multiaxial evaluation A size and form of shadow image rely on the features of spatial location of object or his elements in relation to x-ray and tape (see the fig. 10.6.).

Fig.10.5.Mutual summatsiya images of the explored objects: and - increase of intensity of image; b - reduction of intensity of image.

Fig.10.6. Dependence of sizes of x-ray photography image on distance between focus of tube (F), evaluation object and screen (by tape):

The form of object can change depending on direction of central ray in relation to the long axis of object (see fig. 10.7.) Distortion of form of object it is possible at the receipt of image by a not central bunch, and by lateral x-rays and slanting placing of casets (see fig. 10.8.)

Fig.10.7. Dependence of form of x-ray photography image on placing of the explored object in relation to the bunch of x-ray photography radiation; F - focus of tube.

Fig.10.8. Distortion of image of objects at sciagraphy by the lateral radiation (а) and at slanting rozmeshenii receiver of radiation (б).

Intensity of shade represents the degree of absorption of x-rays and relies on a closeness and thickness of object. Intensity can appear denser as a result of effect of summatsii, I.e. imposition of one shade on other. Intensity of shade can be less to dense at imposition shade on the area of brightening (see Fig.10.9.). The clearness of x-ray photography image relies on the size of optical focus of x-ray tube and remoteness of object from tape (see fig. 10.1.).

Fig. 10.9.Schematic image (and, b, in) of tangential law of x-ray photography tenebrazovaniya.

Fig. 10.10. Dependence of clearness of x-ray photography image on rozmera optical focus (F) of tube (a, b); remoteness of explored obєkta from tape (c, d) and focal distance.

Roentgenologic evaluation of skleta and lights it is possible thanks to their natural kontrasnosti, that is a different closeness of bones and surrounding soft fabrics. Natural kontrasnost lights is conditioned by definite maintenance of air in them.

Дата добавления: 2015-10-23