Which distance factor, when increased, will increase spatial resolution?

Which distance factor, when increased, will increase spatial resolution?

• A. Source-to-image distance (SID)
• B. Object-to-detector distance
• C. Table-to-object distance
• D. Source-to-object distance (SOD)

Answer: (D)

Sharper spatial resolution comes from reducing geometric blur created by the finite size of the focal spot. The blur on the image depends on geometry in a way that scales with the focal spot size and with how the object sits between the source and the detector. A helpful way to think about it is that geometric unsharpness is proportional to the distance from the source to the object (and the distance from the object to the detector) divided by the source-to-object distance. When you increase the distance from the source to the object, and keep the other distances fixed, that ratio decreases, so the blur on the image gets smaller and details become crisper. This is why increasing the source-to-object distance improves spatial resolution. In contrast, making the object sit farther from the detector (increasing object-to-detector distance) increases the blur, since it directly enlarges the geometric spread of the focal spot on the image. Adjustments that change the source-to-image distance can have mixed effects depending on how they alter the object-to-detector geometry, but the most straightforward way to boost resolution is to increase the distance from the source to the object.

Sharper spatial resolution comes from reducing geometric blur created by the finite size of the focal spot. The blur on the image depends on geometry in a way that scales with the focal spot size and with how the object sits between the source and the detector. A helpful way to think about it is that geometric unsharpness is proportional to the distance from the source to the object (and the distance from the object to the detector) divided by the source-to-object distance. When you increase the distance from the source to the object, and keep the other distances fixed, that ratio decreases, so the blur on the image gets smaller and details become crisper. This is why increasing the source-to-object distance improves spatial resolution.

In contrast, making the object sit farther from the detector (increasing object-to-detector distance) increases the blur, since it directly enlarges the geometric spread of the focal spot on the image. Adjustments that change the source-to-image distance can have mixed effects depending on how they alter the object-to-detector geometry, but the most straightforward way to boost resolution is to increase the distance from the source to the object.