2D directional ramp filter

Feriel Khellaf (1) , Nils Krah (1, 2) , Jean Michel Létang (1) , Simon Rit (1)

1 Imagerie Tomographique et Radiothérapie
2 IP2I Lyon - Institut de Physique des 2 Infinis de Lyon

Usual tomographic reconstruction methods start by filtering projections before backpro-jecting the data. In some cases, inverting the filtering and the backprojection steps can be useful to preserve spatial information. In this paper, an intermediate between a filter-backproject and a backproject-filter approach is proposed, based on the extension of the usual ramp filter to two dimensions. To this end, an expression for a band-limited 2D version of the ramp filter is derived. We have tested this filter on simulated X-ray CT projections of a Shepp-Logan phantom and on proton CT list-mode data. We accurately reconstructed the X-ray CT and the proton CT data, although the reconstruction can be slightly noisier than a standard filtered backprojection in some cases. A slight improvement of the spatial resolution of proton CT images reconstructed with this 2D filter has been observed.

Domaines: Imagerie médicale

Feriel Khellaf, Nils Krah, Jean Michel Létang, Simon Rit. 2D directional ramp filter. Physics in Medicine and Biology, 2020, 65 (8), pp.08NT01. ⟨10.1088/1361-6560/ab7875⟩. ⟨hal-02486620⟩