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Motion compensated local tomography

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A Katsevich

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In this paper we develop local tomography (LT) for image reconstruction from motion contaminated data. It is assumed that motion is known. We propose a new LT function fΛ, which is related to an original object f via an operator \mathcal B : f_\Lambda=\mathcal B f . Because of motion, \mathcal B may fail to be a pseudo-differential operator (PDO). We obtain the conditions that guarantee that \mathcal B is a PDO. Under these conditions, similarly to the classical LT in {\bb R}^2, \mathcal B is a PDO of order 1. Computation of fΛ depends on a weight function Φ. We show that Φ can be chosen in such a way that the operator \mathcal B has principal symbol |ξ|. This result has an interesting corollary for conventional exact reconstruction. It suggests a novel frequency-split approach to finding f from motion contaminated data. In practice tomographic data are discrete, and derivatives are usually replaced by their mollified analogs. We consider how mollification affects the singularities of the LT function fΛ. Using this approach we develop an algorithm for finding values of jumps of f using LT. We also consider various aspects of numerical implementation of LT and show the results of numerical experiments.


PACS

87.59.bd Computed radiography

02.30.Tb Operator theory

87.57.N- Image analysis

MSC

92C55 Biomedical imaging and signal processing (See also 44A12, 65R10)

47G30 Pseudodifferential operators (See also 35Sxx, 58Jxx)

Subjects

Mathematical physics

Medical physics

Dates

Issue 4 (August 2008)

Received 10 March 2008, in final form 15 May 2008

Published 24 June 2008



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