The loss of structural sharpness from off-focus radiation within the primary beam is described as decreased:

The loss of structural sharpness from off-focus radiation within the primary beam is described as decreased:

• A. Spatial resolution
• B. Contrast
• C. Brightness
• D. Noise

Answer: (A)

Spatial resolution is the ability to distinguish fine details and sharp edges in an image. When off-focus (extrafocal) radiation is present in the primary beam, photons originate outside the focal spot and add unfocused exposure that blurs object edges. This geometric unsharpness makes fine structures harder to see, so overall image sharpness decreases. The other terms describe different image attributes—contrast is about differences in brightness between structures, brightness is the overall exposure level, and noise is random signal variation—so they don’t capture the blurring effect caused by off-focus radiation.

Spatial resolution is the ability to distinguish fine details and sharp edges in an image. When off-focus (extrafocal) radiation is present in the primary beam, photons originate outside the focal spot and add unfocused exposure that blurs object edges. This geometric unsharpness makes fine structures harder to see, so overall image sharpness decreases. The other terms describe different image attributes—contrast is about differences in brightness between structures, brightness is the overall exposure level, and noise is random signal variation—so they don’t capture the blurring effect caused by off-focus radiation.