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1. Partial volume - occurs when several objects are averaged together in a voxel.

2. Movement - due to mathematical assumption that voxels are located in the same place.

3. Streak - loss of line integral information due to attenuation exceeding system limits.

4. Beam hardening - at different angles, the X‐ray beam can be hardened more than others (e.g. through high density bone).

5. Ring - imperfect detector elements resulting in loss of signal.

6. Stair step - occurs in Sagittal/Coronal MPR images due to straight structures that are oblique to the reconstruction.

7. View aliasing - occurs when too few projections are used for reconstruction of high frequency objects.

8. Helical windmill - helical data interpolation can lead to periodic dark and light streaks (‘windmill’) around high contrast edges.

9. Cone beam - large cone beam angles can lead to undersampling in the cone angle direction (Z‐axis).


1. Bushberg, J. T. (2012). The essential physics of medical imaging. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Find it at Amazon
2. Heggie, J. C., Liddell, N. A., & Maher, K. P. (1997). Applied imaging technology. Melbourne: St. Vincents Hospital.

Ⓒ A. Manickam 2018

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