A microdensitometric study of image quality appears to lend itself satisfactorily to the examination of tomographic images. Multiple films of a standard phantom, con sisting of a strand of 0.254 mm. polished tungsten wire, were exposed throughout the variable geometries of an adjustable-fulcrum tomographic system and a fixed-fulcrum tomographic system. The following general conclusions may be drawn: 1. There is a minimal change in image quality between single emulsion and double emulsion film. These change are below the limits of visibility in the roentgenogram. 2. The addition of intensifying screens produces a significant deterioration of the image throughout both systems. The deterioration is greater in the adjustablefulcrum system and becomes more pronounced as the layer height is elevated above the tabletop and the angle of section is increased. Image deterioration at levels above 10 cm. and with angles greater than 40° are very substantial, leading to significant loss of contrast and increase in image width by magnification and distortion. There is little change in contrast levels throughout the fixed-fulcrum system and, again, there is only minimal magnification and distortion. It is important, therefore, that careful attention be given to the selection of optimal screens in any tomographic system. Image quality will decrease disproportionately throughout the tomographic system when poor screen performance is employed. 3. Image quality is inversely proportional to the size of the focal spot used. It was not possible to draw any specific conclusions between the image quality resulting from the use of an 0.3 mm. tube as compared with an 0.6 mm. tube. There was, however, very significant difference between the small focal spots and the large 1.2 mm. focal spots in both systems. The effect of the large focal spot is, again, disproportionately greater in the adjustable-fulcrum system. It is, therefore, important to use the smallest practical focal spot in any tomographic system. 4. No significant effect was noted in image quality as the result of milliamperage change or whether the tube was cold or at a high temperature level. A very definite effect of image quality was noted when the screen temperature was changed from 17° F. to 95° F. There was significant degeneration of the image at a screen temperature of 95° F. This finding should be investigated more completely with variable screens and beam qualities. It is conceivable that the routine use of low temperature screens would improve the screen performance and ultimately reduce patient exposure. 5. There is inherent far-focus-grid decentering in an adjustable-fulcrum tomographic system. The effect of this type of grid decentering is not significant in the central axis of the tomographic system, but it does become reasonably significant near the periphery of a large image field. The addition of any lateral-grid decentering compounds this effect. Proper grid selection is important in any tomographic system and perhaps a 10:1 ratio grid would be more satisfactory in a tomographic system than a 12:1 ratio grid. The grid in a fixed-fulcrum system is not liable to far-focus-grid decentering and a lateral-focus decentering becomes less significant in the fixed-fulcrum system. 6. DuPont Hi-Plus screens gave the best image quality of this phantom from 8 screens examined and showed better retention of image quality than the other high speed screens. These films were exposed at low kilovoltage levels and this conclusion may not be valid at higher energy levels. 7. Image quality changes noted within the static system are reflected directly in the same proportion in the tomograms. A general deterioration of the image, both in contrast and detail, is noted throughout the adjustable-fulcrum system as the result of increased magnification and distortion and it becomes disproportionately greater for objects displaced from the central axis of the system. Both contrast and image quality are more uniformly maintained through-out a fixed-fulcrum system. 8. Manufacturers are urged to give consideration to these findings in the development of future tomographic devices.