Beam Hardening Artefact
A CBCT image artefact caused by preferential absorption of lower-energy X-ray photons as the beam passes through dense structures, producing dark bands or streaks adjacent to highly radiopaque objects such as metal restorations.
Full Definition
Beam hardening occurs because a polychromatic X-ray beam contains photons of varying energy levels; as the beam traverses dense structures (e.g., amalgam restorations, implants, or cortical bone), low-energy photons are attenuated more rapidly than high-energy ones, shifting the mean energy of the transmitted beam upward ('hardening' it). The reconstruction algorithm, assuming a monochromatic beam, misinterprets this change and generates dark streaks or cupping artefacts in the image. In dental CBCT, beam hardening artefacts near metallic restorations can obscure adjacent root canals, bone defects, or pathology, and must be described accurately in reports. Editors must distinguish this from scatter artefacts and from the related 'metal artefact', which has additional causes.
Usage
Usage note: Use British spelling 'artefact' in UK publications and 'artifact' in US publications; maintain consistency throughout a document. Always specify the causative dense structure (e.g., 'beam hardening artefact adjacent to the amalgam restoration in tooth 36').
In Context
- "Dark streaks radiating from the full-gold crown in tooth 26 were attributed to beam hardening artefact, limiting assessment of the surrounding bone." — CBCT radiographic report
- "The manuscript used 'artifact' and 'artefact' interchangeably; both were standardised to 'artefact' per the journal's house style." — Scientific manuscript copy-editing