DETERMINATION OF Z-EFFECTIVE VALUE FOR SET OF VOXELS USING CT DENSITY IMAGE AND SPARSE MULTI-ENERGY DATA

摘要

Z-effective (e.g., atomic number) values are generated for one or more sets of voxels in a CT density image using sparse (measured) multi-energy projection data. Voxels in the CT density image are assigned a starting z-effective value, causing a CT z-effective image to be generated from the CT density image. The accuracy of the assigned z-effective values is tested by forward projecting the CT z-effective image to generate synthetic multi-energy projection data and comparing the synthetic multi-energy projection data to the sparse multi-energy projection data. When the measure of similarity between the synthetic data and the sparse data is low, the z-effective value assigned to one or more voxels is modified until the measure of similarity is above a specified threshold (e.g., with an associated confidence score), at which point the z-effective values substantially reflect the z-effective values that would be obtained using a (more expensive) dual-energy CT imaging modality.

主权项

1. A method for generating a z-effective value for a set of voxels in a CT density image for a radiography imaging modality, comprising:
acquiring the CT density image of an object; acquiring sparse multi-energy projection data of the object; identifying one or more sets of voxels in the CT density image; setting an initial z-effective value for respective sets of voxels to generate a CT z-effective image; forward projecting the CT z-effective image to generate synthetic multi-energy projection data; comparing the synthetic multi-energy projection data to the sparse multi-energy projection data to determine a measure of similarity between z-effective information of the synthetic multi-energy projection data and z-effective information of the sparse multi-energy projection data; and updating the initial z-effective value for one or more sets of voxels to update the CT z-effective image when the determined measure of similarity between the z-effective information of the synthetic multi-energy projection data and the z-effective information of the sparse multi-energy projection data is below a specified threshold.