Abstract
In X-ray computed tomography, the task of imaging only a local region of interest (ROI) inside a larger sample is very important. However, without a priori information, this ROI cannot be exactly reconstructed using only the image data limited to the ROI. We propose here an approach of region-of-interest tomography, which reconstructs a ROI within an object from projections of different fields of view acquired on a specific angular sampling scheme in the same tomographic experiment. We present a stable procedure that not only yields high-quality images of the ROI but keeps as well the quantitative contrast on the reconstructed images. In addition, we analyze the minimum number of projections required for ROI tomography from the point of view of the band region of the Radon transform, which confirms this number must be estimated based on the size of the entire object and not only on the size of the ROI.
Highlights
In X-ray computed tomography, a 3D image of an object is reconstructed from 2D projections taken at multiple angular directions in a range covering 180 ◦ in general
The inverse Radon transform in two dimensions leads to artifacts on the reconstructed images from truncated projections limited to the region of interest (ROI) of a larger sample, which in turn hampers the extraction of quantitative information from the reconstructed image gray level [1, 3,4,5]
We introduce an approach of Pseudo Region-of-Interest Tomography capable of overcoming these problems, which we will abbreviate Pseudo region-of-interest tomography (PRofIT) for the remainder of this text
Summary
In X-ray computed tomography, a 3D image of an object is reconstructed from 2D projections taken at multiple angular directions in a range covering 180 ◦ in general. Instead of dealing with only truncated data, some approaches which have been proposed are based on dual sampling and dual reconstruction followed by data completion [16,17,18,19,20] The idea behind these methods is measuring conventional projections covering the entire object with reduced resolution and moderately higher-resolution interior projections limited to the ROI. In this approach projections covering different fields of view are measured in the same experiment as schematically shown, such that non-truncated projections are only acquired in a sparse angular sampling grid whereas the ROI is measured with fine angular sampling This method allows for measurements of a ROI with arbitrary diameter within the object while preserving quantitative contrast.
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