A CT scan of the posterior fossa shows dark bands radiating between the petrous temporal bones. Which physical phenomenon is primarily responsible for this artefact?
- A Partial volume averaging
- B Photon starvation
- C Beam hardening ✓
- D Metallic scatter
Correct answer: C. Beam hardening
Explanation
Beam hardening occurs because the polychromatic X-ray beam loses lower-energy photons as it traverses dense bone, raising the mean energy and lowering the CT number. This creates dark bands between dense bony structures, classically seen between the petrous bones in the posterior fossa.
Reference: Goldman, CT and MRI of the Whole Body, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.