What does an increase in SID typically do to image quality?

• A. Decreases resolution
• B. Increases resolution
• C. Has no effect
• D. Causes blurriness

Answer: (B)

An increase in Source-to-Image Distance (SID) typically leads to an increase in image resolution. Resolution in radiography pertains to the ability of the imaging system to distinguish between two adjacent structures. When the SID is increased, the X-ray beam becomes more parallel, which reduces the penumbra—the area of unsharpness around the edge of a structure. A parallel beam helps to minimize geometric distortion and enhances the sharpness of the recorded image.

Moreover, a greater distance allows for a more uniform distribution of X-rays over the image receptor, which contributes to higher image quality. The increased SID can also reduce patient exposure since the intensity of radiation diminishes with distance according to the inverse-square law, making the increase in SID beneficial for both image quality and patient safety.

In summary, a higher SID improves image resolution by reducing blurriness and distortion, allowing for clearer visualization of anatomical details.