Statistical method for material property extraction from multi-energy images

Patent metadata

Field	Value
Publication number	US-2021177366-A1
Application number	US-201916713963-A
Country	US
Kind code	A1
Filing date	Dec 13, 2019
Priority date	Dec 13, 2019
Publication date	Jun 17, 2021
Grant date	—

Abstract

An apparatus for determining material property, includes: an interface configured to obtain a first HU value associated with a first image of an object, and to obtain a second HU value associated with a second image of the object, wherein the first image is created using a first energy having a first energy level, and wherein the second image is created using a second energy having a second energy level that is different from the first energy level; and a processing unit configured to determine a weighted property value for the object based at least in part on the first HU value and the second HU value.

First claim

1 . An apparatus for determining material property, comprising:
an interface configured to obtain a first HU value associated with a first image of an object, and to obtain a second HU value associated with a second image of the object, wherein the first image is created using a first energy having a first energy level, and wherein the second image is created using a second energy having a second energy level that is different from the first energy level; and a processing unit configured to determine a weighted property value for the object based at least in part on the first HU value and the second HU value.

2 . The apparatus of claim 1 , wherein the weighted property value comprises a weighted density for the object.

3 . The apparatus of claim 2 , wherein the weighted density is based on N weights calculated using N metric values for N respective imaging energies.

4 . The apparatus of claim 3 , wherein the N metric values comprises a first metric value that indicates how well the first HU value correlates with a first property identification, and a second metric value that indicates how well the second HU value correlates with a second property identification.

5 . The apparatus of claim 3 , wherein the N metric values are M 1 -M N , and the N weights are W 1 -W N calculated as W n =M n /(Sum (M 1 -M N )), for n=1 to N.

6 . The apparatus of claim 3 , wherein at least one of the N metric values is a goodness metric calculated from calibration error for histogram of HU-value spread of a calibration sample.

7 . The apparatus of claim 1 , wherein the processing unit is configured to determine an identity of the object based on the weighted property value.

8 . The apparatus of claim 1 , wherein the processing unit is also configured to determine a first material fraction based on the first HU value, and a second material fraction based on the second HU value; and
wherein the processing unit is configured to compute a metric for the object based on the first material fraction and the second material fraction.

9 . The apparatus of claim 8 , wherein the metric indicates a percentage or an amount of an identified material in the object.

10 . The apparatus of claim 8 , wherein the processing unit is configured to determine the first material fraction by accessing a non-transitory medium storing material fraction values as a function of HU values, or storing parameter(s) of function(s) associating the material fraction values with HU values.

11 . The apparatus of claim 8 , wherein the processing unit is configured to compute the metric for the object based on the first material fraction and the second material fraction, and also based on a first weight and a second weight.

12 . The apparatus of claim 11 , wherein the metric is based on the first weight times the first material fraction and the second weight times the second material fraction.

13 . The apparatus of claim 11 , wherein each of the first weight and the second weight is based at least on a first metric value and a second metric value.

14 . The apparatus of claim 13 , wherein the first weight is calculated as the first metric value divided by a sum of metric values that includes the first metric value and the second metric value; and
wherein the second weight is calculated as the second metric value divided by the sum of metric values that includes the first metric value and the second metric value.

15 . The apparatus of claim 13 , wherein the first metric value is a goodness metric calculated from calibration error for histogram of HU-value spread of a calibration sample.

16 . The apparatus of claim 1 , wherein each of the first image and the second image comprises a CT image or a x-ray image.

17 . The apparatus of claim 1 , further comprising an imaging device configured to generate the first image and the second image, wherein the imaging device is a part of a medical device or a part of an object scanner.

18 . A method performed by an apparatus, comprising:
obtaining, by an interface of the apparatus, a first HU value associated with a first image of an object, and to obtain a second HU value associated with a second image of the object, wherein the first image is created using a first energy having a first energy level, and wherein the second image is created using a second energy having a second energy level that is different from the first energy level; and determining, by a processing unit of the apparatus, a weighted property value for the object based at least in part on the first HU value and the second HU value.

19 . The method of claim 18 , further comprising determining, by the processing unit, a first material fraction based on the first HU value, and a second material fraction based on the second HU value; and
computing, by the processing unit, a metric for the object based on the first material fraction and the second material fraction.

Assignees

• Varian Medical Systems Int Ag

Inventors

• Hytonen Roni
• Koponen Timo K
• Niemela Perttu

Classifications

• G06T12/30

  Image post-processing, e.g. metal artefact correction · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title

• A61B6/583

  using calibration phantoms · CPC title

• A61B6/482 Primary

  involving multiple energy imaging · CPC title

• A61B6/5205

  involving processing of raw data to produce diagnostic data · CPC title