Beam hardening in x-ray reconstructive tomography

Phys Med Biol. 1976 May;21(3):390-8. doi: 10.1088/0031-9155/21/3/004.

Abstract

As a polychromatic X-ray beam passes through matter, low energy photons are preferentially absorbed, and the (logarithmic) attenuation is no longer a linear function of absorber thickness. This leads to various artifacts in reconstructive tomography. If a water bag is used, the nonlinear attenuation in bone causes a distortion of the bone values and a spill-over inside the skull, or 'pseudo-cortex' artifact. If no water bag is used, there is an additional effect due to the varying thickness of soft tissue which causes a depression of interior values, or 'cupping'. Both artifacts can be remedied by additional prefiltering of the beam and by applying a linearization correction to the detector outputs.

Publication types

  • Historical Article

MeSH terms

  • Diagnosis, Computer-Assisted*
  • History of Medicine
  • Tomography, X-Ray*