How does increasing the SID influence spatial resolution?

Increasing the Source-to-Image Distance (SID) has a significant impact on spatial resolution. Spatial resolution refers to the ability of an imaging system to distinguish small details in the image. When the SID is increased, the x-ray beam diverges less as it travels towards the image receptor. This reduction in divergence results in a sharper image because the x-rays spread less as they hit the detector, leading to improved detail and clearer visualization of structures.

Moreover, a longer SID minimizes the effects of geometric unsharpness. Geometric unsharpness occurs due to the inherent spreading of the x-ray beam, which may blur the edges of the structures being imaged. With a larger distance, the x-ray source effectively becomes more 'point-like', enhancing the clarity of details.

In summary, an increased SID enhances the spatial resolution by ensuring that the x-ray beam maintains a more focused path to the image receptor, allowing finer details to be captured without significant blurring.