Which situation would decrease magnification and increase spatial resolution?

Which situation would decrease magnification and increase spatial resolution?

• A. Decrease OID, increase SID
• B. Increase OID, increase SID
• C. Decrease SID, decrease OID
• D. Increase OID, decrease SID

Answer: (A)

Increasing the distance from the x‑ray source to the image receptor (SID) while bringing the object closer to the receptor (decreasing the object-to-image distance, OID) lowers geometric magnification and reduces geometric blur. When SID gets larger, the rays spread less between the focal spot and the image, so the image is less magnified. At the same time, shrinking OID reduces the penumbra footprint on the image because the object sits nearer to the detector, cutting down blur at edges. Together, these moves produce a smaller magnification factor and less geometric unsharpness, which means sharper detail and higher spatial resolution. Conversely, increasing OID or decreasing SID increases magnification and blur, degrading resolution.

Increasing the distance from the x‑ray source to the image receptor (SID) while bringing the object closer to the receptor (decreasing the object-to-image distance, OID) lowers geometric magnification and reduces geometric blur. When SID gets larger, the rays spread less between the focal spot and the image, so the image is less magnified. At the same time, shrinking OID reduces the penumbra footprint on the image because the object sits nearer to the detector, cutting down blur at edges. Together, these moves produce a smaller magnification factor and less geometric unsharpness, which means sharper detail and higher spatial resolution. Conversely, increasing OID or decreasing SID increases magnification and blur, degrading resolution.