Roentgenogram

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Roentgenogram

 

the image of an object that is recorded on a photosensitive material, such as film or a photographic plate, as a result of the interaction of X rays with matter. When an object is irradiated with X rays, absorption, reflection, or diffraction of the X rays may occur. The spatial distribution of the X-ray intensity after this type of interaction is recorded on a roentgenogram.

A roentgenogram that gives a shadowy image of an object is obtained as a result of the nonidentical absorption of X rays by different parts of the object; this type of roentgenogram is called an absorption roentgenogram. It is used to investigate biological objects, particularly in medicine. It is also used to detect various flaws in materials and structures and to find inho-mogeneities in the structures of inorganic materials (projection X-ray microscopy).

Diffraction roentgenograms are obtained as a result of the diffraction scattering of X rays by crystalline specimens and are used in X-ray diffraction analysis. Diffraction roentgenograms are known by different names, depending on the type of substance under study (polycrystals or single crystals), the character of the X-radiation used (continuous-spectrum or monochromatic), and the geometric conditions of photography. The debye powder pattern, the Laue pattern, and rotating (rocking) roentgenograms are diffraction patterns recorded by rotating or rocking the crystal while it is being photographed. The Weis-senberg pattern and kforograms are roentgenograms obtained by the synchronous rotation of a single crystal and advance of the photographic film. The Kossel pattern, which is obtained in a widely divergent beam of monochromatic X-radiation, and X-ray topograms are other roentgenograms.

Small-angle scattering roentgenograms formed near the primary X-ray beam develop as a result of the diffraction of X rays in crystalline bodies having a large lattice spacing. They also develop as a result of the diffuse scattering of the substance under study on microinhomogeneities.

Roentgenograms that record the intensity distribution of X-radiation that has undergone complete external reflection from the surface of the body under study are used in X-ray re-flectometry to estimate the physical and geometric parameters of surface layers and thin films.

Roentgenograms are taken in X-ray cameras using different photosensitive materials, the selection of which depends on the goals of the investigation. Roentgenograms generally do not require further optical magnification, and they therefore are recorded on low-resolution X-ray or Polaroid film. Diffraction and absorption microroentgenograms and X-ray topograms requiring further optical magnification are recorded on small-grain high-resolution photographic films or plates.

REFERENCES

Dmokhovskii, V. V. Osnovy rentgenotekhniki. Moscow, 1960.
Trapeznikov, A. K. Rentgeno-defektoskopiia. Moscow, 1948.
Guinier, A. Rentgenografiia kristallov: Teoriia ipraktika. Moscow, 1961. (Translated from French.)
Taylor, A. Rentgenovskaia metallografiia. Moscow, 1965. (Translated from English.)
Umanskii, la. S. Rentgenografiia metallov. Moscow, 1967.
Rovinskii, V. M., V. M. Sinaiskii, and V. I. Sidenko. “Rentgenovskaia reflektometriia.” Apparatura i metody rentgenovskogo analiza, 1970, issue 7.

E. P. KOSTIUKOVA

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