On the strength of streak artifacts in limited angle weighted X-ray transform

TL;DR

This paper analyzes the limited angle weighted X-ray transform, decomposing the reconstruction operators into components responsible for visible features and artifacts, and provides microlocal estimates for artifact strength.

Contribution

It introduces a decomposition of the limited angle reconstruction operators into Fourier integral operators, revealing the origins of artifacts and their microlocal properties.

Findings

Operators decompose into parts responsible for visible features and artifacts

Continuity and geometry of artifacts are characterized microlocally

Refined estimates for artifact strength are obtained

Abstract

In this article, we study the limited angle problem for the weighted X-ray transform. We consider the approximate reconstructions by applying two filtered back projection formulas to the limited data. We prove that each resulted operator can be decomposed into the sum of three Fourier integral operators whose symbols are of types $(\varrho,\delta) \neq (1,0)$. The first operator, being a pseudo-differential operator, is responsible for the reconstruction of visible singularities. The other two are responsible for the generation of the artifacts. The theory of Fourier integral operators then implies, in particular, the continuity of the reconstruction operator and geometry of the artifacts. We then extend the technique developed by the author in [Inverse Problems 31 (2015) 055003] to obtain more refined microlocal estimates for the strength of the artifacts.