# US 9,435,900 B2 · X-ray system utilizing alternating spectrum x-ray source in conjuction with a fixed spectrum separation filter approval

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- Number: US 9,435,900 B2
- Document ID: US9435900B2
- Status: Granted
- Kind: B2
- Application number: 13/491,412
- Filed: 2012-06-07
- Published: 2012-12-13
- Granted: 2016-09-06
- Earliest claimed: 2011-06-08
- Assignees: The Board of Trustees of the Leland Stanford Junior University
- Applicants: Yuan Yao; Norbert J. Pelc
- Inventors: Yuan Yao; Norbert J. Pelc
- Web page: https://patentgrep.com/patent/US9435900B2

## CPC

- G01T 1/2985: {In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); (using external radiation sources A61B6/02)}
- A61B 6/4042: {K-edge filters}
- G01N 23/046: using tomography, e.g. computed tomography [CT]
- G01N 23/087: using polyenergetic X-rays
- G01N 2223/419: computed tomograph
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An apparatus for x-ray imaging of an object is provided. An x-ray source for providing alternating x-ray spectrums is placed on a first side of the object. A spectrum separation fixed filter is placed between the x-ray source and the object. An x-ray detector is placed on a second side of the object opposite the x-ray source. A controller controls the x-ray source and the x-ray detector.

## Claims

### Claim 1

An apparatus for x-ray imaging of an object, comprising:
an x-ray source for providing alternating x-ray spectrums placed on a first side of the object;
a spectrum separation fixed filter between the x-ray source and the object, wherein the fixed filter does not move or change with respect to the x-ray source during a scan, wherein alternating x-ray spectrums pass through the spectrum separation fixed filter along a common path, so that the fixed filter increases spectrum separation of the alternating x-ray spectrums;
an x-ray detector placed on a second side of the object opposite the x-ray source; and
a controller for controlling the x-ray source and the x-ray detector.

### Claim 2 (depends on 1)

The apparatus, as recited in claim 1, wherein the spectrum separation fixed filter comprises an atomic element with an atomic number between 60 and 72 inclusive.

### Claim 3 (depends on 2)

The apparatus, as recited in claim 2, wherein the x-ray source provides kVp switching between at least two different kVp potentials.

### Claim 4 (depends on 3)

The apparatus, as recited in claim 3, wherein the spectrum separation fixed filter comprises Gadolinium.

### Claim 5 (depends on 4)

The apparatus, as recited in claim 4, wherein the spectrum separation fixed filter has a uniform thickness.

### Claim 6 (depends on 1)

The apparatus, as recited in claim 1, wherein the apparatus for x-ray imaging is a multiple kVp switching x-ray computed tomography (CT) system.

### Claim 7 (depends on 6)

The apparatus, as recited in claim 6, wherein the x-ray CT system further comprises:
a gantry for supporting the x-ray source, spectrum separation fixed filter, and x-ray detector and for rotating the x-ray source, spectrum separation fixed filter, and x-ray detector around the object and an axis of rotation; and
a translation system for moving the object relative to the gantry along the axis of rotation.

### Claim 8 (depends on 3)

The apparatus, as recited in claim 3, wherein the spectrum separation fixed filter is a single filter element wherein x-rays from the at least two different kVp potentials pass through the single filter element.

### Claim 9 (depends on 2)

The apparatus, as recited in claim 2, wherein the spectrum separation fixed filter provides a precision improvement of more than 40%.

### Claim 10 (depends on 2)

The apparatus, as recited in claim 2, wherein the spectrum separation fixed filter comprises Gd2O2S.

### Claim 11

A method for providing x-ray imaging of an object, comprising:
a) providing from an x-ray source with at least two different alternating kVp x-rays with a first kVp potential and a second kVp potential;
b) passing the alternating kVp x-rays through a spectrum separation fixed filter, wherein the alternating kVp x-rays pass through the spectrum separation fixed filter along a common path, so that the spectrum separation fixed filter increases spectrum separation between x-rays with the first kVp potential and x-rays with the second kVp potential, wherein the fixed filter does not move or change with respect to the x-ray source during a scan;
c) passing the kVp x-rays through the object;
d) detecting at a detector the x-rays that pass through the object at the first kVp potential and the second kVp potential;
e) applying material decomposition to detected x-rays; and
f) using the material decomposition to generate an image.

### Claim 12 (depends on 11)

The method, as recited in claim 11, wherein the single spectrum separation fixed filter comprises an atomic element with an atomic number between 60 and 72 inclusive.

### Claim 13 (depends on 12)

The method, as recited in claim 12, wherein the spectrum separation fixed filter comprises Gadolinium.

### Claim 14 (depends on 13)

The method, as recited in claim 13, wherein the spectrum separation fixed filter has a uniform thickness.

### Claim 15 (depends on 14)

The method, as recited in claim 14, further comprising:
rotating the x-ray source, spectrum separation fixed filter, and the detector around an axis of rotation; and
translating the object relative to the x-ray source, spectrum separation fixed filter, and detector along the axis of rotation.

### Claim 16 (depends on 15)

The method, as recited in claim 15, wherein the using the material decomposition to generate the image uses computed tomography.

### Claim 17 (depends on 16)

The method, as recited in claim 16, wherein the spectrum separation fixed filter comprises Gd2O2S.

### Claim 18 (depends on 12)

The method, as recited in claim 12, wherein the spectrum separation fixed filter provides a precision improvement of more than 40%.

### Claim 19 (depends on 12)

The method, as recited in claim 12, wherein the spectrum separation fixed filter comprises Gd2O2S.