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CT WITH 3D SCOUT FOR PET ATTENUATION CORRECTION

IP.com Disclosure Number: IPCOM000249965D
Publication Date: 2017-May-10
Document File: 5 page(s) / 295K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method for using multi-energy (e.g. 3D) scout data for PET CT attenuation correction (CTAC). The 3D scout images collected at an energy level that is different from the actual CT scan are used for second order beam hardening correction to improve the CTAC accuracy.

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CT WITH 3D SCOUT FOR PET ATTENUATION CORRECTION

BACKGROUND

 

The present disclosure relates generally to computed tomography (CT) and Positron emission tomography (PET), and more particularly to CT/PET attenuation correction using 3D scout.

One of the challenges in CT-based attenuation correction with PET/CT is that contrast agents, implants, or calcium deposits can cause incorrect values in PET image unless correct CT-based attenuation correction tables are used. Conventional techniques for improving PET/CT attenuation correction accuracy via DECT include DECT (rot-rot) which operates by changing the CT imaging workflow and increases the radiation dose; DECT (fast switching/2T2D) which requires hardware not available on today’s PET/CT scanners; Model based DECT, which is based on iterative recon, is more time consuming, and therefore has reduced practicality.

Therefore, there exists a need for improved attenuation correction techniques in CT/PET.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow diagram of a method for using 3D scout for attenuation correction.

FIG. 2 illustrates a flow diagram of a method for a projection-based implementation utilizing a matched scanning protocol between scout and actual CT scan.

FIG. 3 illustrates a flow diagram of a method for an image-based implementation utilizing any scanning protocol for 3D scout imaging.

FIGS. 4 and 5 depict the improvement in the results of both CT attenuation map and PET image.

DETAILED DESCRIPTION

The disclosure presents a PET/CT attenuation correction technique using 3D scout, and can correct the beam hardening artifacts without increasing the total radiation dose. The multi-energy scout data for PET CT attenuation correction (CTAC), that is, the 3D scout images are collected at an energy level that is different from the actual CT scan. The scout data is then used for a 2nd order beam hardening correction to improve the CTAC accuracy.

Specifically, contrast agents, implants, or calcium deposits can cause incorrect values in PET image, unless correct CT-based attenuation correction tables are used. Further, bias in the CT image due to beam-hardening and scatter from the arms in the field of view may also cause issues with CTAC. The techniques described further below address these issues with the conventional techniques for PET CTAC.

FIG. 1

FIG. 1 is a flow diagram of a method for using 3D scout for attenuation correction. As shown, the method begins with generating 3D scout data at one energy. Next, the scan range is defined, and thereafter, a CT scan is performed at another energy. Next, image-based or projection-based material decomposition (MD) is implemented (each described further below with respect to FIGS. 2 and 3). Next, the basis material is combined for generating a monochromatic image at 511 keV.

FIG. 2

FIG. 2 illustrates a flow diagram of a method for a projection-based implementation utilizing a matched scanning protocol between scout and actual CT scan, however, at m...