Fig. 6.

Effects of streak artefacts with and without shields. Streak artefacts in a soft-tissue window (400/40 HU) after shielding were detected at a low energy of 80 kVp. (A) A computed tomography image without a bismuth shield. (B) A streak artefact was observed at the interface between a 1-ply bismuth shield and the phantom surface. (C) The streak artefact was reduced using a 1-ply bismuth shield and with a 1-cm foam rubber sheet. (D) Increased streak artefacts were observed when a 3-ply shield was used.