Sponsor:
This work was supported in part by from Ministerio de Educación y Ciencia (FIS-PI052583 and TEC2004-07052-C02), Ministerio de Industria (CD-TEAM, CENIT program) and Comunidad de Madrid (GR/SAL/024104).
Low-pass filtering sinograms prior to reconstruction is a general practice to reduce noise. Sinograms are generally filtered in the radial direction, although other filtering schemes have been proposed.
It is known that the Fourier transform of a sinogram shoLow-pass filtering sinograms prior to reconstruction is a general practice to reduce noise. Sinograms are generally filtered in the radial direction, although other filtering schemes have been proposed.
It is known that the Fourier transform of a sinogram shows a particular shape of the spectral energy distribution (“bow-tie”).
In this work, this property has been exploited to perform an adapted filter, whose performance has been compared with previously reported methods: angular, axial and stackgram domain filtering.
Stackgram and angular filtering degraded resolution (~16 and ~5.7 % respectively) while no significant enhancement in contrast to noise ratio (CNR) was achieved. Angular filtering resulted in a circle blurring artifact dependant on the distance to the center of the FOV.
Bow-tie filtering showed the best results (enhancement of ~26% in resolution and of ~12% in CNR). Axial filtering degraded resolution but enhanced CNR (~14 %), appearing as a good strategy to reduce radial filtering. Experiments on rodent images showed a noticeable image quality enhancement achieved when using bow-tie filtering combined with radial and axial filters.[+][-]
Description:
Proceeding of: 2006 IEEE Nuclear Science Symposium Conference Record, San Diego, CA, Oct. 29 - Nov. 1, 2006