To increase scatter reaching the image receptor, which change would be most effective?

To increase scatter reaching the image receptor, which change would be most effective?

• A. Increase kVp
• B. Increase grid ratio
• C. Increase mA while decreasing time
• D. Increase focal spot size

Answer: (A)

Increasing the kilovoltage peak (kVp) is the most effective way to boost scatter reaching the image receptor. As kVp rises, photons become more penetrating, so a larger fraction of interactions in the patient produce scatter photons that can escape and travel toward the detector. This raises the scatter-to-primary ratio, meaning more scattered photons reach the receptor, even though higher kVp also lowers image contrast. The other options don’t promote more scatter reaching the receptor. A higher grid ratio absorbs more scattered photons before they reach the detector. Keeping the same mAs by increasing current and decreasing time changes exposure quantity but not the tendency for scatter to reach the receptor in the same way as changing energy. Increasing focal spot size mainly affects geometric sharpness, not the amount of scatter incident on the receptor.

Increasing the kilovoltage peak (kVp) is the most effective way to boost scatter reaching the image receptor. As kVp rises, photons become more penetrating, so a larger fraction of interactions in the patient produce scatter photons that can escape and travel toward the detector. This raises the scatter-to-primary ratio, meaning more scattered photons reach the receptor, even though higher kVp also lowers image contrast.

The other options don’t promote more scatter reaching the receptor. A higher grid ratio absorbs more scattered photons before they reach the detector. Keeping the same mAs by increasing current and decreasing time changes exposure quantity but not the tendency for scatter to reach the receptor in the same way as changing energy. Increasing focal spot size mainly affects geometric sharpness, not the amount of scatter incident on the receptor.