Beam hardening artifact in CT is characterized by what and how is it mitigated?

• A. Filtration, higher kVp, thinner slices, and metal artifact reduction algorithms
• B. Dark spots in soft tissue that require lower kVp
• C. Bright halos around bone due to scattering mitigated by increased exposure
• D. No significant artifact mitigated by lowering dose

Answer: (A)

Beam hardening happens when the x‑ray beam loses the soft, low‑energy photons as it passes through dense material, shifting toward higher energies. This nonuniform spectrum causes artifacts such as dark streaks or shading between dense structures like bone or metal implants. The best way to counter this is to adjust the beam and the reconstruction: add filtration to remove the low-energy photons, use a higher kVp to produce a fuller, higher-energy spectrum, and use thinner slices to reduce partial-volume effects that contribute to streaking. Modern CT also employs metal artifact reduction algorithms to lessen the streaks and shading around dense objects. Lowering dose or relying on lower kVp alone doesn’t address beam hardening and can worsen image quality in those regions.