In CT imaging, beam hardening artifact occurs because:
- A The X-ray beam becomes more monochromatic as it passes through tissue
- B The detector array fails to register high-energy photons
- C Lower energy photons are preferentially absorbed, increasing the mean energy of the beam ✓
- D Scattered radiation is absorbed by the patient
Correct answer: C. Lower energy photons are preferentially absorbed, increasing the mean energy of the beam
Explanation
Beam hardening occurs because the polychromatic X-ray beam's lower energy photons are preferentially absorbed as it passes through tissue, leaving higher energy photons and increasing the mean beam energy. This causes artifacts such as cupping and dark bands between dense structures. Option A is incorrect because the beam does not become truly monochromatic.
Reference: Radiology Physics: A Handbook for Students and Teachers, 1st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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