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The possibility of application of radiography in production and study of vegetable seeds and its advantages (rapid test method, multipurpose application etc.) are described in the article

IntroductionThe goal of this work was to discuss recent informa tion available from international sources indicating that X ray focal spot size has an effect on the quality of images obtained using radiovisiographs [1,2]. It was reported in [2] that focal spot size reduction from 0.8 × 0.8 to 0.4 × 0.4 mm increased sharpness of dental images.In the domestic medical literature the problem of correlation of X ray focal spot size and image quality had been discussed in detail [3]. The effects on the image sharpness, contrast, exposure dose, and power consump tion were discussed for the case of a dental X ray tube with diameter of 0.1 mm [4]. In collaboration with one of the leading domestic manufacturers of X ray equipment, further research was performed to study the special case of dental radiovisiography. MaterialsStandard contact X ray was used in the study [5]. The X ray focal spot diameter d was 1 mm. The distance f from the object to the X ray source was large, while the distance to the detector was very short to provide contact X ray. The focal spot diameter d and distance f from the object to the X ray source exerted a significant effect on image quality (sharpness). The distance f was selected to meet the requirements for X ray image sharpness taking into account the actual values of focal spot diameter d 1 and object thickness. Even slight changes in the distance Δf resulted in considerable reduction of the image sharpness.The ratio ( f + Δf ) determines magnification of the image of the object m: At focal spot diameter d and detector resolution R n the maximal resolution is calculated from [6]:This equation shows that the maximal resolution of modern dental systems depends on focal spot diameter. The dependence for the typical value of R n = 20 line pairs per mm is given in Table 1.Focal spot diameter d = 0.1 mm and R n = 20 line pairs per mm provide a 10% increase in the X ray system resolution relative to contact X ray with d = 0.7 mm. Focal spot diameter d = 0.05 mm provides a 1.4 fold increase in the X ray system resolution. MethodsContact X ray of a reference test pattern and a dental X ray of a skeletonized mandible with soft tissue phantom

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