Which two factors will result in improved spatial resolution?

The improvement of spatial resolution in radiographic imaging is influenced by several factors, two of which are specifically pertinent in this question.

Increased source-to-image distance (also known as SID) enhances spatial resolution primarily by reducing the effects of geometric unsharpness. When the distance between the X-ray source and the image receptor is greater, the X-rays diverge less by the time they reach the film or digital detector, leading to a sharper image. This is because the rays are more parallel as they travel to the receptor, which minimizes the blurring effects that can occur with shorter distances.

Decreased focal spot size is another critical factor that improves spatial resolution. A smaller focal spot produces less penumbra, or blurred edges around the images, which enhances the clarity and detail of the structures being imaged. This is particularly important when imaging small anatomical structures or when high detail is required.

In contrast, increased film speed and reduced patient movement do not inherently lead to improved spatial resolution. Increased film speed relates more to the sensitivity of the film to radiation, meaning that it can produce an image with less exposure time but may lead to a decrease in detail. Reduced patient movement is certainly crucial for achieving a clear image but does not directly enhance the inherent