Multiple Image Collection and Synthesis for Personnel Screening

Abstract

An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a given subject. A positioner provides for relative motion of each beam vis-à-vis the subject in a motion, the vertical component of which is one-way. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject.

1 . An apparatus for ascertaining a material feature associated with a given subject, the apparatus comprising:
 a. a first source of penetrating radiation, including a first collimator, adapted to produce a first beam of penetrating radiation incident on the subject;   b. a first actuator adapted to move the first source of penetrating radiation with respect to the given subject so as to scan the subject by moving the first beam of penetrating radiation in a motion including vertical travel, wherein all travel in a vertical direction is one-way during a course of inspection of a first side of the given subject;   c. a second source of penetrating radiation, including a second collimator, adapted to produce a second beam of penetrating radiation incident on the given subject;   d. a second actuator adapted to move the second source of penetrating radiation with respect to the given subject so as to scan the given subject by moving the second beam of penetrating radiation in a motion including vertical travel, wherein all travel in a vertical direction is one-way during a course of inspection of a second side of the given subject;   e. at least one detector for receiving radiation produced by at least one of the first and second sources after interaction of the penetrating radiation with the given subject and for generating a scatter signal; and   f. a processor for identifying a threat material based at least on the scatter signal.   
     
     
         2 . An apparatus according to  claim 1 , wherein the at least one detector is disposed on the first carriage. 
     
     
         3 . An apparatus according to  claim 1 , wherein the given subject is a person. 
     
     
         4 . An apparatus according to  claim 1 , wherein the penetrating radiation is x-ray radiation. 
     
     
         5 . An apparatus according to  claim 1 , wherein the first and second sources are adapted to each produce a pencil beam of radiation. 
     
     
         6 . An apparatus according to  claim 5 , wherein each carriage includes a scanner adapted to move the pencil beam of penetrating radiation produced by the respective source transverse to a current direction of motion of the carriage. 
     
     
         7 . An apparatus according to  claim 6 , wherein the scanner is a chopper wheel. 
     
     
         8 . An apparatus according to  claim 7 , wherein the chopper wheels are adapted to provide interleaved beams. 
     
     
         9 . An apparatus according to  claim 1 , wherein each carriage further comprises a plurality of detectors. 
     
     
         10 . An apparatus according to  claim 9 , wherein each carriage includes at least one of a scatter and transmission detector. 
     
     
         11 . An apparatus according to  claim 10 , wherein the first source on first carriage and the second source on the second carriage produce substantially oppositely directed beams of penetrating radiation. 
     
     
         12 . An apparatus according to  claim 11 , wherein the transmission detector of the first carriage is disposed at an elevation substantially equal to that of the source of the second carriage. 
     
     
         13 . An apparatus according to  claim 1 , wherein each of the first and second sources is an intermittently irradiating source, for providing a temporally interlaced irradiation pattern. 
     
     
         14 . An apparatus according to  claim 1  further comprising a processor for receiving a signal from the at least one detector and for producing an image based at least on the signal. 
     
     
         15 . An apparatus according to  claim 14 , further comprising:
 a processor for electronically combining images produced on a basis of signals from a plurality of detectors.   
     
     
         16 . An apparatus according to  claim 1 , further comprising an enclosure for containing the carriages and the at least one positioner during the course of operation. 
     
     
         17 . A method for inspecting a given subject comprising:
 moving a first source of penetrating radiation with respect to the given subject so as to scan the given subject by moving a first beam of penetrating radiation in a motion including vertical travel, wherein all travel of the first beam in a vertical direction is one-way during a course of a scan of a first side of the given subject;   moving a second source of penetrating radiation with respect to the given subject so as to scan the given subject by moving a second beam of penetrating radiation in a motion including vertical travel, wherein all travel of the second beam in a vertical direction is one-way during a course of a scan of a second side of the given subject;   detecting, with at least one detector, radiation produced by at least one of the first and second sources after interaction of the penetrating radiation with the given subject;   generating a detector output signal based on radiation received by the at least one detector; and   characterizing the given subject on the basis of the detector output signal.   
     
     
         18 . A method according to  claim 17  wherein the at least one detector is coupled to at least one of the first carriage and the second carriage. 
     
     
         19 . A method according to  claim 17  further comprising scanning the beam of penetrating radiation produced by the source in a direction transverse to the direction of motion of the carriages. 
     
     
         20 . A method according to  claim 17  further comprising creating an image based on radiation detected by the at least one detector.