What will happen to image contrast when changing from a 1.5 mm focal spot to a 0.5 mm focal spot?

When transitioning from a 1.5 mm focal spot to a 0.5 mm focal spot, the primary effect is not on image contrast, but rather on spatial resolution. A smaller focal spot size typically results in improved spatial resolution, allowing for more detailed images and finer structures to be visualized. However, image contrast, which refers to the difference in density between various areas of the image, remains relatively unchanged with this modification.

The focal spot size primarily influences geometric unsharpness; a smaller focal spot reduces this unsharpness, enhancing clarity and sharpness of sharply defined edges without necessarily altering the contrast of the image. Therefore, while the quality of the image may improve due to higher resolution, the inherent contrast provided by the imaging technique remains stable. Thus, the outcome of maintaining the same level of image contrast highlights the lack of significant interaction between focal spot size and contrast in this context.