# US 10,762,998 B2 · X-ray scanning system

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- Number: US 10,762,998 B2
- Document ID: US10762998B2
- Status: Granted
- Kind: B2
- Application number: 15/527,566
- Filed: 2015-11-20
- Published: 2017-12-14
- Granted: 2020-09-01
- Earliest claimed: 2014-11-20
- Assignees: Viken Detection Corporation
- Applicants: Viken Detection Corporation
- Inventors: Peter John Rothschild
- Web page: https://patentgrep.com/patent/US10762998B2

## CPC

- G21K 1/043: {changing time structure of beams by mechanical means, e.g. choppers, spinning filter wheels}
- G01V 5/222: measuring scattered radiation
- G01V 5/224: {Multiple energy techniques using one type of radiation, e.g. X-rays of different energies}
- G21K: HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

An x-ray scanning system includes an x-ray source that produces a collimated fan beam of incident x-ray radiation. The system also includes a chopper wheel that can be irradiated by the collimated fan beam. The chopper wheel is oriented with a wheel plane containing the chopper wheel substantially non-perpendicular relative to a beam plane containing the collimated fan beam. In various embodiments, a disk chopper wheel's effective thickness is increased, allowing x-ray scanning with end point energies of hundreds of keV using relatively thinner, lighter, and less costly chopper wheel disks. Backscatter detectors can be mounted to an exterior surface of a vehicle housing the x-ray source, and slits in the disk chopper wheel can be tapered for more uniform target irradiation.

## Claims

### Claim 1

An x-ray scanning system comprising:
an x-ray source configured to produce a collimated fan beam of incident x-ray radiation; and
a chopper wheel, configured to be irradiated by the collimated fan beam, oriented with a wheel plane containing the chopper wheel non-perpendicular relative to a beam plane containing the collimated fan beam of incident radiation.

### Claim 2 (depends on 1)

The x-ray scanning system of claim 1, wherein an angle between the wheel plane containing the chopper wheel and the beam plane containing the collimated fan beam of incident radiation is less than 30°.

### Claim 3 (depends on 2)

The x-ray scanning system of claim 2, wherein the angle between the wheel plane containing the chopper wheel and the beam plane containing the collimated fan beam of incident radiation is less than 15°.

### Claim 4 (depends on 1)

The x-ray scanning system of claim 1, wherein the chopper wheel is a disk with a rim and a center, the disk including one or more radial slits extending toward the rim of the disk and toward the center of the disk, and the one or more slits being configured to pass x-ray radiation from the collimated fan beam.

### Claim 5 (depends on 4)

The x-ray scanning system of claim 4, wherein the one or more slits are tapered slits having greater width toward the rim of the disk than toward the center of the disk.

### Claim 6 (depends on 4)

The x-ray scanning system of claim 4, wherein the chopper wheel includes chamfering on at least two edges or on all edges of the one or more slits.

### Claim 7 (depends on 1)

The x-ray scanning system of claim 1, wherein the one or more slits are tapered slits having greater width toward the rim of the disk than toward the center of the disk, and wherein the chopper wheel includes chamfering on at least two edges or on all edges of the one or more slits.

### Claim 8 (depends on 1)

The x-ray scanning system of claim 1, wherein the x-ray source is further configured to produce the collimated fan beam of incident x-ray radiation with end-point x-ray energies in a range between about 50 keV and 500 keV.

### Claim 9 (depends on 1)

The x-ray scanning system of claim 1, wherein the x-ray source is further configured to produce the collimated fan beam of incident x-ray radiation with end-point x-ray energies in a range between about 200 keV and 250 keV.

### Claim 10 (depends on 1)

The x-ray scanning system of claim 1, the system further comprising one or more backscatter detectors configured to detect x-ray radiation backscattered by objects irradiated by the incident radiation having passed through the chopper wheel.

### Claim 11 (depends on 10)

The x-ray scanning system of claim 10, wherein the one or more backscatter detectors are mounted to an external surface of a vehicle.

### Claim 12 (depends on 11)

The x-ray scanning system of claim 11, wherein the one or more backscatter detectors are fixedly mounted to the exterior surface of the vehicle, and wherein the one or more backscatter detectors are wavelength-shifting fiber (WSF) detectors.

### Claim 13

A method of x-ray scanning, the method comprising:
producing a collimated fan beam of incident x-ray radiation; and
effecting rotation of a chopper wheel, configured to be irradiated by the collimated fan beam, in a wheel rotation plane that is non-perpendicular relative to a beam plane containing the collimated fan beam of incident radiation.

### Claim 14 (depends on 13)

The method of claim 13, wherein effecting rotation of the chopper wheel includes causing the rotation with an angle between the wheel rotation plane of the chopper wheel and the beam plane containing the collimated fan beam of incident radiation being less than 30°.

### Claim 15 (depends on 14)

The method of claim 14, wherein effecting rotation of the chopper wheel includes causing the rotation with an angle between the wheel rotation plane of the chopper wheel and the beam plane containing the collimated fan beam of incident radiation being less than 15°.

### Claim 16 (depends on 13)

The method of claim 13, wherein effecting rotation of the chopper wheel includes using a disk chopper wheel with a rim, a center, and one or more radial slits extending toward the rim of the disk and toward the center of the disk, the one or more slits being configured to pass x-ray radiation from the collimated fan beam.

### Claim 17 (depends on 16)

The method of claim 16, wherein effecting rotation further includes using the disk chopper wheel with one or more tapered slits having greater width toward the rim of the disk than toward the center of the disk.

### Claim 18 (depends on 16)

The method of claim 16, wherein effecting rotation of the chopper wheel further includes using the disk chopper wheel with chamfering on at least two edges or on all edges of the one or more slits.

### Claim 19 (depends on 13)

The method of claim 13, wherein effecting rotation further includes using the disk chopper wheel with one or more tapered slits having greater width toward the rim of the disk than toward the center of the disk, effecting rotation further including using the disk chopper wheel with chamfering on at least two edges or on all edges of the one or more slits.

### Claim 20 (depends on 13)

The method of claim 13, wherein producing the collimated fan beam includes producing x-rays with end-point energies between about 50 keV and 500 keV.

### Claim 21 (depends on 13)

The method of claim 13, wherein producing the collimated fan beam further includes producing x-rays with end-point energies between about 200keV and 250 keV.

### Claim 22 (depends on 13)

The method of claim 13, further comprising detecting x-ray radiation backscattered by objects irradiated by the incident radiation having passed through the chopper wheel.

### Claim 23 (depends on 22)

The method of claim 22, wherein detecting the backscattered x-ray radiation includes using one or more backscatter x-ray detectors mounted to an external surface of a vehicle.