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A Radiometry Tolerant Method for Direct 3D/2D Registration of Computed Tomography Data to X-ray Images : Transfer Function Independent Registration

Selby, Peter and Sakas, Georgios and Walter, Stefan and Groch, Wolfgang-Dieter and Stilla, Uwe (2010):
A Radiometry Tolerant Method for Direct 3D/2D Registration of Computed Tomography Data to X-ray Images : Transfer Function Independent Registration.
In: Informatik aktuell, Springer, Berlin; Heidelberg; New York, In: Bildverarbeitung für die Medizin 2010. Proceedings, pp. 117-121, [Conference or Workshop Item]

Abstract

As exact dose delivery is essential for radiological cancer treatment, image-guided radiotherapy (IGRT) methods are used to estimate corrections of the tumor alignment. This is often done through comparison of a Computed Tomography (CT) to the patient alignment visible in digital radiography images (DRs) acquired from within the treatment device. Digitally Reconstructed Radiography Images (DRRs) computed from the CT are then geometrically registered to the DRs. A problem is that radiometric properties of DRs and DRRs can vary profoundly. If a registration algorithm does not use volumetric CT data directly it is unable to regard deviations of the physical image formation to the simulated image formation. We present a novel method allowing direct DR to CT registration. It is designed to be radiometry tolerant by adapting the simulated X-ray transfer function to observed DR intensities. This is done by solving an overdetermined system of equations given by the histograms along rays through the voxel matrix of the CT. Remaining errors serve as measure for the image dissimilarity, thus minimization in 6 degrees of freedom (DOF) gives the transformation between the images. Thereby higher radiometric tolerance can be achieved, as misalignments can be identified even if DR images are acquired with inappropriate radiation parameters.

Item Type: Conference or Workshop Item
Erschienen: 2010
Creators: Selby, Peter and Sakas, Georgios and Walter, Stefan and Groch, Wolfgang-Dieter and Stilla, Uwe
Title: A Radiometry Tolerant Method for Direct 3D/2D Registration of Computed Tomography Data to X-ray Images : Transfer Function Independent Registration
Language: English
Abstract:

As exact dose delivery is essential for radiological cancer treatment, image-guided radiotherapy (IGRT) methods are used to estimate corrections of the tumor alignment. This is often done through comparison of a Computed Tomography (CT) to the patient alignment visible in digital radiography images (DRs) acquired from within the treatment device. Digitally Reconstructed Radiography Images (DRRs) computed from the CT are then geometrically registered to the DRs. A problem is that radiometric properties of DRs and DRRs can vary profoundly. If a registration algorithm does not use volumetric CT data directly it is unable to regard deviations of the physical image formation to the simulated image formation. We present a novel method allowing direct DR to CT registration. It is designed to be radiometry tolerant by adapting the simulated X-ray transfer function to observed DR intensities. This is done by solving an overdetermined system of equations given by the histograms along rays through the voxel matrix of the CT. Remaining errors serve as measure for the image dissimilarity, thus minimization in 6 degrees of freedom (DOF) gives the transformation between the images. Thereby higher radiometric tolerance can be achieved, as misalignments can be identified even if DR images are acquired with inappropriate radiation parameters.

Series Name: Informatik aktuell
Publisher: Springer, Berlin; Heidelberg; New York
Uncontrolled Keywords: Image registration, X-ray, Transfer functions, Ray tracing, Computed tomography (CT)
Divisions: 20 Department of Computer Science
20 Department of Computer Science > Interactive Graphics Systems
Event Title: Bildverarbeitung für die Medizin 2010. Proceedings
Date Deposited: 12 Nov 2018 11:16
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