COVERT SURVEILLANCE USING MULTI-MODALITY SENSING

• US 20130039472A1
• Filed: 02/07/2012
• Published: 02/14/2013
• Est. Priority Date: 02/08/2011
• Status: Active Grant

• Current Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Original Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Inventors: Morton, Edward James
• Granted Patent: US 8,903,046 B2
• Time in Patent Office: Days
• US Class Current: 378/88
• CPC Class Codes: G01V 5/222 measuring scattered radiation
• CPC Class Codes: G01V 5/223 Mixed interrogation beams, e.g. using more than one type of radiation beam
• CPC Class Codes: G01V 5/224 Multiple energy techniques using one type of radiation, e.g. X-rays of different energies

Abstract

The present specification discloses a covert mobile inspection vehicle with a backscatter X-ray scanning system that has an X-ray source and detectors for obtaining a radiographic image of an object outside the vehicle. The systems preferably include at least one sensor for determining a distance from at least one of the detectors to points on the surface of the object being scanned, a processor for processing the obtained radiographic image by using the determined distance of the object to obtain an atomic number of each material contained in the object, and one or more sensors to obtain surveillance data from a predefined area surrounding the vehicle.

Claims

1. A covert mobile inspection vehicle for obtaining a radiographic image of an object, having a surface, outside the vehicle, comprising:

a. a backscatter X-ray scanning system comprising an X-ray source and a plurality of detectors;

b. at least one sensor for determining a distance from at least one of the plurality of detectors to points on the surface of the object;

c. a processor for processing the obtained radiographic image by using the determined distance of the surface of the object to obtain an atomic number of material contained in the object; and

d. one or more sensors to obtain surveillance data from a predefined area surrounding the vehicle.

2. The covert mobile inspection vehicle as claimed in claim 1 wherein the at least one sensor is a laser range finder causing a beam of infra-red light to be scattered from the surface of the object and wherein a time taken for the beam of infra-red light to return to the sensor is indicative of a distance to the surface of the object.

3. The covert mobile inspection vehicle as claimed in claim 1 wherein the processor causes an intensity correction to be applied to the obtained radiographic image thereby causing intensity of the image of an object located at a distance greater than a predefined distance to be reduced by a predefined factor and intensity of the image of an object located at a distance lesser than a predefined distance to be increased by a predefined factor.

4. The covert mobile inspection vehicle as claimed in claim 1 wherein the processor implements an adaptive region based averaging method whereby backscattered X-rays from a first region of the object located at a distance greater than a predefined distance from the X-ray source are averaged over a second larger predefined region, causing a linear dimension of the first region to be scaled as a square of the distance from X-ray source to the object.

5. The covert mobile inspection vehicle as claimed in claim 4 wherein the adaptive region averaging method is implemented by using a statistical filter to determine if a first pixel of an obtained radiographic image is part of a first object or of a second adjacent object.

6. The covert mobile inspection vehicle as claimed in claim 1 wherein one or more individual pixels in the obtained radiographic image are colored based on the determined distance of the object and an atomic number of each material contained in the object.

7. The covert mobile inspection vehicle as claimed in claim 1 wherein the obtained distance of the object is used to provide a geometric correction to produce a true likeness of the shape of the object.

8. The covert mobile inspection vehicle as claimed in claim 1 wherein the X-ray source comprises an X-ray tube having a cathode-anode potential difference ranging from 160 kV to 320 kV and a tube current ranging from 1 mA to 50 mA for producing a broad spectrum of X-ray energies.

9. The covert mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprise one of:

an inorganic scintillation detector, a detector comprising NaI(T1), or an organic scintillator such as polyvinyl toluene and wherein each detector is coupled with one or more light sensitive readout devices such as a photomultiplier tube or a photodiode.

10. The covert mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprise semiconductor sensors having a wide bandgap which can operate at room temperature.

11. The covert mobile inspection vehicle as claimed in claim 1 wherein the plurality of detectors comprises semiconductor sensors having a narrow bandgap.

12. The covert mobile inspection vehicle as claimed in claim 1 further comprising a data acquisition module comprising a plurality of detectors, photomultipliers/photodiodes and analog-to-digital converter circuitry.

13. The covert mobile inspection vehicle as claimed in claim 1 further comprising at least one of:

a GPS receiver, a scanning laser, a CCTV camera, an infra-red camera, an audio microphone, a directional RF antenna, a wide-band antenna, a chemical sensor, or a jamming device.

14. The covert mobile inspection vehicle as claimed in claim 1 further comprising an automated detection processor for:

a. integrating and analyzing in real time surveillance data from the one or more sensors; and

b. sending threat items obtained by analyzing the surveillance data for review to an operator via wired or wireless means.

15. The covert mobile inspection vehicle as claimed in claim 1 further comprising a transmitter for broadcasting the surveillance data to a central intelligence location in real time.

16. The covert mobile inspection vehicle as claimed in claim 1 wherein the X-ray source comprises a multi-element scatter collimator to produce a fan beam of X rays for irradiating the object being scanned and wherein X rays backscattered from the object are detected by a segmented detector array located behind the multi-element collimator.

17. A method for obtaining an atomic number (Z) of each material contained in an object being scanned by a covert mobile inspection vehicle comprising:

a backscatter X-ray scanning system comprising an X-ray source and a plurality of detectors for obtaining a radiographic image of the object;

at least one sensor for determining a distance from at least one of the plurality of detectors to points on a surface of the object; and

a processor for processing the obtained radiographic image by using the determined distance of the object to obtain an atomic number of each material contained in the object;

the method comprising the steps of;

a. determining a true extent of each region of the radiographic image by using a statistical filter;

b. calculating a standard deviation of energies of pixels present in each region;

c. calculating a product of the obtained standard deviation and a mean of the energies of pixels present in each region; and

d. comparing the calculated product to a pre-determined scale where a low value of the product corresponds to a low Z material and a high value of the product corresponds to a high Z material.

18. A covert mobile inspection vehicle comprising:

a. a backscatter X-ray scanning system comprising an X-ray source and a plurality of detectors for obtaining a radiographic image of an object outside the vehicle; and

b. one or more sensors to obtain surveillance data from a predefined area surrounding the vehicle.

19. The covert mobile inspection vehicle as claimed in claim 18 wherein at least one of the sensors is a scanning laser range finder causing a beam of infra-red light to be scattered from the surface of the object and wherein a time taken for the beam of infra-red light to return to the sensor is indicative of the distance to the surface of the object.

20. The covert mobile inspection vehicle as claimed in claim 18 further comprising at least one sensor for determining a distance from at least one of the plurality of detectors to points on the surface of the object;

and a processor for processing the obtained radiographic image by using the determined distance of the object to obtain an atomic number of each material contained in the object.

21. The covert mobile inspection vehicle as claimed in claim 20 wherein the processor causes an intensity correction to be applied to the obtained radiographic image thereby causing intensity of the image of an object located at a distance greater than a predefined distance to be reduced by a predefined factor and intensity of the image of an object located at a distance lesser than a predefined distance to be increased by a predefined factor.

22. The covert mobile inspection vehicle as claimed in claim 18 wherein the plurality of detectors comprise one of:

an inorganic scintillation detector, a detector comprising NaI(T1), an organic scintillator, or a detector comprising polyvinyl toluene and wherein each detector is coupled with one or more light sensitive readout devices such as a photomultiplier tube or a photodiode.

23. The covert mobile inspection vehicle as claimed in claim 18 wherein the plurality of detectors comprise at least one of CdTe, CdZnTe or HgI.

24. The covert mobile inspection vehicle as claimed in claim 18 wherein the plurality of detectors comprise at least one of HPGe.

25. The covert mobile inspection vehicle as claimed in claim 18 further comprising a data acquisition module comprising a plurality of detectors, photomultipliers/photodiodes and analog-to-digital converter circuitry.

26. The covert mobile inspection vehicle as claimed in claim 18 further comprising at least one of:

a GPS receiver, a scanning laser, a CCTV camera, an infra-red camera, an audio microphone, a directional RF antenna, a wide-band antenna, a chemical sensor, or a jamming device.