To maximize sharpness, which change would be true?

To maximize sharpness, which change would be true?

• A. Increase SID
• B. Increase OID
• C. Decrease SID
• D. Increase tube voltage

Answer: (A)

Sharpness in an X‑ray image is mainly about geometric unsharpness from the finite focal spot. The blur that reaches the image plane scales with the focal spot size and with the ratio of object-to-image distance to source-to-image distance. Increasing the source-to-image distance reduces this blur, so edges appear crisper. Increasing the object-to-image distance would worsen blur, and decreasing the source-to-image distance would also worsen sharpness. Tube voltage changes energy and contrast but does not reduce geometric blur. So the way to maximize sharpness is to increase the distance between the X-ray source and the image receptor.

Sharpness in an X‑ray image is mainly about geometric unsharpness from the finite focal spot. The blur that reaches the image plane scales with the focal spot size and with the ratio of object-to-image distance to source-to-image distance. Increasing the source-to-image distance reduces this blur, so edges appear crisper. Increasing the object-to-image distance would worsen blur, and decreasing the source-to-image distance would also worsen sharpness. Tube voltage changes energy and contrast but does not reduce geometric blur. So the way to maximize sharpness is to increase the distance between the X-ray source and the image receptor.