Which interaction is the primary source of scattered photons that may degrade image quality at higher kVp?

Which interaction is the primary source of scattered photons that may degrade image quality at higher kVp?

• A. Photoelectric interaction
• B. Coherent scatter
• C. Compton interaction
• D. Pair production

Answer: (C)

At higher kVp, x-ray photons are more energetic, so Compton scattering becomes the dominant interaction in soft tissue. In a Compton event, a photon transfers some of its energy to a loosely bound electron and is deflected in a new direction. The scattered photon then travels toward the image receptor from various angles, creating background fog that reduces image contrast and sharpness. Coherent (Rayleigh) scatter occurs mainly at very low energies and contributes little to detector fog at diagnostic energies, while pair production requires energies well beyond diagnostic ranges. Photoelectric interactions remove photons from the beam rather than scatter them. This is why Compton scattering is the primary source of scattered photons degrading image quality at higher kVp.

At higher kVp, x-ray photons are more energetic, so Compton scattering becomes the dominant interaction in soft tissue. In a Compton event, a photon transfers some of its energy to a loosely bound electron and is deflected in a new direction. The scattered photon then travels toward the image receptor from various angles, creating background fog that reduces image contrast and sharpness. Coherent (Rayleigh) scatter occurs mainly at very low energies and contributes little to detector fog at diagnostic energies, while pair production requires energies well beyond diagnostic ranges. Photoelectric interactions remove photons from the beam rather than scatter them. This is why Compton scattering is the primary source of scattered photons degrading image quality at higher kVp.