The noise power spectrum in computed X-ray tomography

S. J. Riederer, N. J. Pelc, D. A. Chesler

Research output: Contribution to journalArticlepeer-review

172 Scopus citations


An expression is derived showing that the two-dimensional noise power spectrum of computed X-ray tomography is proportional to mod G(k) mod 2/k where k is the radial spatial frequency and G(k) is the one-dimensional corrective filter used in the filtered back-projection reconstruction technique. It is shown that predicted noise power spectra compare well with those estimated from CT reconstructions of simulated noise for both the ramp filter and the Hanning-weighted ramp filter. A consequence of the non-uniform shape of the noise power spectrum is that statistical noise in CT reconstructions is correlated from point to point. Because of this correlation when the reconstructed CT values are averaged over some region, the uncertainty of the average depends on the shape of the region as well as its area. This dependence is confirmed by computer simulations.

Original languageEnglish (US)
Article number008
Pages (from-to)446-454
Number of pages9
JournalPhysics in medicine and biology
Issue number3
StatePublished - 1978

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging


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