Patent Publication Number: US-2010123571-A1

Title: Inspection system and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The embodiments described herein relate generally to inspection systems used to inspect a person and, more particularly, to an inspection system configured to inspect a person for a target material. 
     2. Description of the Related Art 
     The Transportation Security Administration (TSA) has recently mandated more stringent inspection procedures be implemented by the travel industry to reduce the possibility of passengers boarding a carrier, such as an aircraft, carrying concealed weapons, explosives, and/or other contraband. To facilitate preventing passengers boarding a plane carrying concealed weapons, explosives, and/or other contraband, the TSA requires that all passengers be screened and/or inspected prior to boarding the carrier. 
     In some known inspection systems, passengers arriving at the airport terminal first submit to a manual verification process that generally includes presenting a boarding pass and a form of identification, such as a driver&#39;s license or passport, to security personnel. The security personnel then manually verify that the passenger has a valid boarding pass, that the name on the identification corresponds to the name on the boarding pass, and that the picture on the identification corresponds to the passenger presenting the identification and the boarding pass to the security personnel. After the manual verification process is completed, the passenger is requested to walk through a metal detector to ensure that the passenger is not carrying any concealed weapon. 
     While the current passenger screening process is reliable, the process may require additional security personnel to perform the screening procedures. As a result, the cost of implementing an effective passenger screening process at a transportation terminal is increased. Moreover, the time required to perform the screening process is increased, thus, necessitating passengers to arrive relatively early to allow the passenger sufficient time to complete the screening process. 
     Further, at least some known inspection systems are configured to detect contraband, however, some benign objects may appear to be benign but include and/or conceal a contraband material. As such, there is a need to detect such materials and/or objects. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a method is provided. The method includes determining a position of a person within an inspection system, and performing a sensor system scan using a sensor system within the inspection system. The sensor system scan includes detecting an unusual physical characteristic of at least one of the person and an item on the person. The results of the sensor system scan are output. 
     In another aspect, an inspection system for inspecting a person for a presence of a target material is provided. The inspection system includes a screening system for performing a target material scan and a sensor system configured to detect an unusual physical characteristic of the person and/or an item on the person. 
     The embodiments described herein facilitate determining whether an object includes unusual physical characteristics such that the object may be more thoroughly inspected. As used herein, the term “unusual physical characteristic” refers to a measured physical characteristic that deviates from average physical characteristics for a particular object as determined by a model, a range, and/or a threshold. For example, an unusual physical characteristic is a statistical outlier as compared to data for physical characteristics for a sample group of objects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-8  show exemplary embodiments of the system and method described herein. 
         FIG. 1  is a perspective view of an exemplary inspection system for inspecting a person. 
         FIG. 2  is a simplified block diagram of the inspection system shown in  FIG. 1 . 
         FIG. 3  is perspective view of a sensor system that may be used with the system shown in  FIG. 1 . 
         FIG. 4  is a flowchart of an exemplary embodiment of a method for inspecting a person that may be used with the inspection system shown in  FIGS. 1-3 . 
         FIG. 5  is a flowchart of a first alternative embodiment of the method shown in  FIG. 4 . 
         FIG. 6  is a flowchart of a second alternative embodiment of the method shown in  FIG. 4 . 
         FIG. 7  is a flowchart of a third alternative embodiment of the method shown in  FIG. 4 . 
         FIG. 8  is a perspective view of an alternative inspection system for inspecting a person. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The systems described herein include a sensor system for detecting a physical characteristic of a person and/or an item on the person. A “person,” as described throughout this description, includes any person attempting to gain access to a restricted area. For example, a person may be a passenger attempting to gain access to an aircraft. Further, a “physical characteristic,” as described throughout this description, includes a temperature, a size, a shape, and/or any other measurable physical characteristic. As used herein, the term “unusual,” when referring to a physical characteristic, is a characteristic that is not within a predetermined range, model, and/or threshold. For example, an unusual physical characteristic is a physical characteristic having a measured value that is a statistical outlier. Moreover, an “item on a person,” as described throughout this disclosure, includes any item that a person may carry, wear, transport, and/or otherwise possess on, near, or in the person&#39;s body. For example, an item on a person may be a shoe that is worn by the person into the restricted area. 
     Particular reference will be made throughout this description to a person that is screened for a “target material.” However, it is to be understood that the present invention is not so limited and that many other applications are envisioned and possible within the teachings of this disclosure. For example, the inspection systems described herein may be implemented in seaports, public buildings, public transportation facilities, prisons, hospitals, power plants, court houses, office buildings, hotels, casinos, and/or any other suitable location. Additionally, the inspection systems described herein may also be used to inspect any suitable object. 
     Further, as used herein, a “target material” is any material for which the inspection process is performed to detect. In the exemplary embodiment, the target material is contraband, such as illegal substances, explosives, narcotics, weapons, a threat object, and/or any other material that a person is not allowed to possess. Moreover, although “security personnel” are referred to herein, any suitable third party may monitor, control, and/or otherwise operate the inspection system described herein to inspect a person and/or an object. As such, the terms “security personnel” and “third party” are used interchangeably herein. 
       FIG. 1  is a perspective view of an exemplary inspection system  10 .  FIG. 2  is a simplified schematic illustration of inspection system  10 .  FIG. 3  is perspective view of a sensor system  64  that may be used with inspection system  10 . As shown in  FIG. 2 , and in the exemplary embodiment, inspection system  10  includes at least a first modality  12 , referred to herein as an identity verification system  13 , a second modality  14 , referred to herein as a screening system  15 , a third modality  16 , referred to herein as a characteristic detection system  17 , and a fourth modality  18 , referred to herein as a metal detection system  19 . 
     Inspection system  10  includes at least one computer  20  and a communications bus  22 , which is coupled between modalities  12 ,  14 ,  16 , and  18 , and computer  20  to enable operator commands to be sent to at least one modality  12 ,  14 ,  16 , and/or  18  and to allow outputs generated by modalities  12 ,  14 ,  16 , and  18  to be delivered to computer  20  and/or used by computer  20  for data analysis or utilized by an operator of computer  20 . In one embodiment, modalities  12 ,  14 ,  16 , and  18  are hardwired to computer  20 . In an alternative embodiment, communications bus  22  is a local area network (LAN). Optionally, communications bus  22  includes an internet connection. 
     Modalities  12 ,  14 ,  16 , and  18  are integrated into a single inspection system  10 . In the exemplary embodiment, modalities  12 ,  14 ,  16 , and  18 , and computer  20  are each housed within a single kiosk or housing  24 . Optionally, computer  20  is housed separately from kiosk  24  and electrically coupled to modalities  12 ,  14 ,  16 , and  18  through communications bus  22 . As used herein, a “kiosk” is defined as a relatively small area that is at least partially defined by at least one wall. 
     Referring to  FIG. 1 , kiosk  24  includes a first wall  26 , a second wall  28  that is positioned substantially parallel to first wall  26 , and a third wall  30  that is positioned substantially perpendicular to and coupled between first wall  26  and second wall  28 . More specifically, third wall  30  is coupled between first wall  26  and second wall  28  to at least partially enclose a passenger screening area  31 . Kiosk  24  also includes a floor  32  extending between first wall  26 , second wall  28 , and third wall  30 . In the exemplary embodiment, floor  32  includes an inductive sensor  34  that is described in further detail below. For example, and as shown in  FIG. 1 , walls  26 ,  28 , and  30  define a single opening  36  such that a person may enter and exit kiosk  24  through opening  36 . Details of the exemplary embodiment of kiosk  24  can be found in U.S. application Ser. No. 11/456,748, filed Jul. 11, 2006 and/or U.S. application Ser. No. 11/456,742, filed Jul. 11, 2006. Optionally, kiosk  24  may include first wall  26  and second wall  28 , but not third wall  30 , such that the passenger may enter kiosk  24  through a first opening, proceed through kiosk  24 , and exit kiosk  24  through a second opening. 
     In the exemplary embodiment, kiosk  24  also includes a control panel section  40  that is coupled to third wall  30  and extends upwardly from third wall  30  to a predetermined height to facilitate providing various operator controls that are used by a person to operate inspection system  10 . Control panel section  40  also includes a monitoring or display device  42  that can be used to prompt a person to either input selected information into inspection system  10  and/or prompt a person to perform various actions within inspection system  10  to facilitate expediently verifying the identity of the person and inspect the person for a target material, as described herein. 
     In the exemplary embodiment, to facilitate verifying a person&#39;s identity, inspection system  10  includes an electronic card reader  44 . In the exemplary embodiment, carder reader  44  includes a receptacle configured to receive a person&#39;s registration card. For example, in the exemplary embodiment, the person&#39;s registration card includes biometric information of the person that has been encoded onto the registration card obtained by the person during a prescreening process. For example, a person may obtain a registration card by registering with the Registered Traveler Program (RTP). In registering with the RTP, the person is pre-screened by the TSA or some other authorized screening entity, to obtain biometric information that is then stored on the person&#39;s registration card. The biometric information may include the person&#39;s fingerprints, iris scan information, hand print information, voice recognition information, and/or other suitable biometric information. The information on the registration may be encoded on a magnetic strip, use optical read codes, use an RF-read memory chip, and/or other embedded media. 
     The information collected during the prescreening process is then stored within or provided to inspection system  10 , for example, via electronic card reader  44  reading the registration card, such that when the person enters kiosk  24 , the verified information is compared to the information presented by the person within kiosk  24  to facilitate reducing the amount of time to complete screening a person and thus improve the convenience of screening. In the exemplary embodiment, during operation of inspection system  10 , the person inserts his/her registration card into electronic card reader  44 . Identity verification system  13  then prompts the person to position a selected body part, such as an eye and/or a fingertip, on a sensor that is utilized to collect biometric information from the person within kiosk  24 . The collected information is then compared to the biometric information stored on the registration card to verify the identity of the person. 
     In the exemplary embodiment, identity verification system  13  is implemented utilizing an iris scan device  46  to generate biometric information that is then compared to the information on, for example, the Registered Traveler&#39;s registration card, in order to verify that the person being screened is the person to whom the card in fact belongs. In an alternative embodiment, identity verification system  13  is implemented utilizing a fingerprint scan device  48 . A person places a finger on fingerprint scan device  48  such that fingerprint scan device  48  obtains an image of the fingerprint of the person for verification. Optionally, identity verification system  13  is implemented by using a hand scanning device, a facial image recognition system, and/or a voice recognition system in order to verify the identity of the person. 
     In the exemplary embodiment, screening system  15  is implemented using a quadrupole resonance (QR), or nuclear quadrupole resonance (NQR), detection system that uses quadrupole resonance to detect explosives such as, but not limited to, C4, Semtex, Detasheet, TNT, ANFO, and/or HMX. More specifically, the QR detection system is configured similarly to the quadrupole resonance system described in U.S. application Ser. No. 11/456,748. In the exemplary embodiment, the QR detection system includes a radio frequency source, a pulse programmer and RF gate, and an RF power amplifier that are configured to generate a plurality of radio frequency pulses having a predetermined frequency to be applied to a coil, such as inductive sensor  34 . More specifically, inductive sensor  34  is positioned proximate third wall  30  approximately between first wall  26  and second wall  28 . In one embodiment, inductive sensor  34  is positioned within a recessed region (not shown) of floor  32 , between an entrance ramp  50  and third wall  30 . The recessed region may also be referred to as a sensor housing. 
     During operation of inductive sensor  34 , in the exemplary embodiment, the person stands with his/her left foot positioned relative to a first current branch  52  of inductive sensor  34  and his/her right foot positioned relative to second current branch  54  of inductive sensor  34 . Inductive sensor  34  then performs the screening process using NQR to detect the presence of a target material associated with the person. In the exemplary embodiment, current flows between first current branch  52  and second current branch  54  during operation since first current branch  52  and second current branch  54  are electrically coupled via entrance ramp  50  and/or the sensor housing. As such, current is directed oppositely through each branch resulting in current flowing from toe to heel along first current branch  52 , and from heel to toe along second current branch  54 . In the exemplary embodiment, inductive sensor  34  is positioned within the sensor housing to form a non-conductive gap between first current branch  52  and second current branch  54 . The gap enables the magnetic fields to circulate about first current branch  52  and second current branch  54 . 
     In the exemplary embodiment, metal detection system  19  includes a pair metal detection coils  56  in conjunction with inductive sensor  34 . Each metal detection coil  56  is configured to detect a target material, such as conductive objects, present within the vicinity of the lower extremities of the inspected person. An example of metal detection system  19  is described in U.S. application Ser. No. 11/456,748 and/or U.S. application Ser. No. 11/456,742. Signals generated by metal detection system  19  are communicated to a suitable computing device, such as, computer  20 . Moreover, metal detection system  19  generally relies on the similarity of metallic parts in shoes and/or on the presence of a metallic object skewing the symmetry of the metal distribution between the person&#39;s feet, which skews the magnetic field generated about the person. As such, to facilitate optimizing the performance of system  10 , the person&#39;s feet are placed nearly symmetrically over QR coils  58  of the QR detection system and between metal detection coils  56  of metal detection system  19  such that misplacement of a foot does not generate a false asymmetry alarm. Accordingly, a positioning device  60  is used to determine the placement of each foot within the inspection system  10 . 
     More specifically, to facilitate optimizing the identification and screening operation of inspection system  10 , the person being inspected is positioned within inspection system  10  such that the person&#39;s feet are positioned within a predetermined screening area to provide optimal screening conditions for both the first, second, and third screening modalities. Accordingly, inspection system  10  includes positioning device  60  for determining that the person&#39;s feet are within the predetermined area. More specifically, the volume of space interrogated by screening system  15  and/or metal detection system  19  is finite, and as such, positioning device  60  also facilitates ensuring that the person&#39;s feet remain within the interrogation volume, for example, the predetermined screening area, throughout a scan period. Positioning device  60  may include any position verification device described in U.S. application Ser. No. 11/456,748. 
     In the exemplary embodiment, screening system  15  is alternatively, or additionally, implemented using a fingertip trace explosive detection system  62 . Fingertip trace explosive detection system  62  is configured to detect minute particles of interest such as traces of a target material, such as narcotics, explosives, and/or other contraband on the person&#39;s finger and/or hand, for example. In the exemplary embodiment, fingertip trace explosive detection system  62  is located proximate to a boarding pass scanner (not shown) such that, as the person scans the boarding pass, at least a portion of the person&#39;s hand passes over fingertip trace explosive detection system  62 . Optionally, the person is prompted to press a button to activate fingertip trace explosive detection system  62  such that the trace target materials on the finger surface are collected and then analyzed by fingertip trace explosive detection system  62 . 
     In the exemplary embodiment, third modality  16 , or characteristic detection system  17 , includes a sensor system  64  having an array of sensors  66 , as shown in  FIG. 3 . Alternatively, sensor system  64  may includes at least one sensor  66 . In the exemplary embodiment, sensor  66  is configured to detect at least one physical characteristic of the person&#39;s body and/or item on the person, such as the person&#39;s shoes. In an alternative embodiment, the array of sensors  66  includes a plurality of types of sensors. For example, the array of sensors  66  includes at least one temperature sensor, at least one shape sensor, and/or at least one position sensor. Alternatively, the array of sensors  66  includes a plurality of the same type of sensor. In the exemplary embodiment, sensor system  64  also includes a database of pre-stored physical characteristics to which a measured physical characteristic is compared. The database is in communication with sensor system  64  and may be within computer  20  or separate from computer  20 . In the exemplary embodiment, sensor  66  measures a physical characteristic of the person and/or the item on the person to pre-stored statistical data within the database to determine if the measured characteristic is a statistical outlier. A statistical outlier may indicate the presence of and/or activity near a target material. 
     In an alternative embodiment, sensor system  64  includes a camera for imaging a person&#39;s feet in inspection system  10 . More specifically, the camera may be a video camera, an infrared camera, and/or any other suitable type of camera. The camera is in communication with computer  20  for displaying and/or analyzing images generated by the camera. For example, when an image is displayed, a third party can inspect the person&#39;s shoes and/or the person can see the position of his/her feet to ensure correct positioning within inspection system  10 . Upon inspection of the person&#39;s shoes and/or feet by the third party, the person may be prompted to reposition her/her feet and/or may be further inspected. In another example, computer  20  includes software, such as machine vision software, for analyzing an image of the person&#39;s foot and/or feet to alarm and/or prompt the person to reposition his/her foot and/or feet. In still another embodiment, floor  32  includes footprint shaped indicators thereon that indicate an optimal and/or proper position for each foot. The camera images the person&#39;s feet and/or foot to verify that the footprint shaped indicators, and/or a predetermined portion thereof, are concealed by the person&#39;s feet. 
     More specifically, in the exemplary embodiment, sensor  66  is a temperature sensor that measures a temperature of each of the person&#39;s shoes. For example, sensor  66  is a thermopile that is a non-contact infrared temperature sensor. Alternatively, sensor  66  may be a non-contact temperature sensor, an infrared temperature sensor, a contact temperature sensor, and/or any other suitable temperature sensor. In the exemplary embodiment, each sensor  66  includes a sensing zone  68  that is represented in  FIG. 3  as a cone. Each sensor  66  measures a temperature of an object, such as the person&#39;s foot, that intercepts sensing zone  68 . 
     In the exemplary embodiment, a plurality of sensors  66  are positioned adjacent the person&#39;s feet on, for example, first wall  26 , second wall  28 , and/or third wall  30 . More specifically, inspection system  10  includes a first array  70  of sensors  66  on each of first wall  26  and second wall  28  and a pair of a second arrays  72  of sensors  66  on third wall  30 . More specifically, each first array  70  is configured to measure a temperature at at least one of the person&#39;s ankle, heel, and/or side of the foot, and each second array  72  is configured to measure a temperature at at least one of the top and/or front of the person&#39;s foot. Each of the pair of second arrays  72  is positioned adjacent one of the person&#39;s feet. Output of sensors  66  of arrays  70  and/or  72  are combined to generate a temperature profile, an average temperature, and/or other suitable indication of the temperature of the person&#39;s feet and/or shoes. 
     In the exemplary embodiment, each sensor  66  of first array  70  is oriented laterally such that an axis  74  of a respective sensing zone  68  is substantially perpendicular to floor  32 . Further, each sensor  66  of second array is oriented obliquely such that axis  74  of a respective sensing zone  68  is oriented at an acute angle  0  to third wall  30 . Alternatively, axes  74  of sensors  66  in first array  70  and/or second array  72  may be oriented at any suitable angle to walls  26 ,  28 , and/or  30  and/or to floor  32  that enables inspection system  10  to function as described herein. In the exemplary embodiment, sensors  66  are oriented toward the person&#39;s feet and/or shoes to measure a general local temperature and/or temperature gradient of and/or proximate the person&#39;s lower extremities, such as the person&#39;s feet and/or shoes. More specifically, sensors  66  are oriented and/or positioned to measure predetermined portions of the person&#39;s feet and/or shoes. 
     In an alternative embodiment, sensor system  64  includes contact temperature sensors  66  positioned on floor  32  such that the person stands on sensors  66  when positioned within kiosk  24 . More specifically, when the person&#39;s stands on sensors  66 , sensor system  64  measures the temperature of the person&#39;s feet and/or shoes. 
     In the exemplary embodiment, sensor  66  and the database are used to determine if any unusual physical characteristic is present. As discussed above, an unusual physical characteristic is a physical characteristic having a measured value that is not within a predetermined range, model, and/or threshold, such as a statistical outlier. For example, shoes having a measured temperature that is above or below a predetermined range of temperatures are considered to be unusual. More specifically, in the exemplary embodiment, the unusualness of the person&#39;s lower extremities, such as the shoes, is determined by comparing the measured temperature and/or temperature gradient to pre-stored temperatures and/or temperature gradients within the database. An unusual temperature and/or temperature gradient may warrant further screening of the person&#39;s lower extremities. Further, having shoes within a predetermined temperature range facilitates optimizing the performance of a QR sensor, such as inductive sensor  34 . Accordingly, a shoe having a temperature falling outside of the predetermined temperature range may be screened using detection systems other than inductive sensor  34 . 
     In an alternative embodiment, sensor  66  is a sensor configured to determine the shape and/or configuration of a shoe and/or a foot and compare the sensed shape and/or configuration with pre-stored shapes and/or configurations, such as a statistical model of shoe shapes, within the database. In such an embodiment, sensor  66  is, but is not limited to being, an infrared sensor, an ultrasound probe, a capacitive sensor, and/or an inductive sensor. In the exemplary embodiment, sensor system  64  includes an array of infrared sensors  66  for determining a size, shape, and/or position of the person&#39;s foot and/or shoe. Alternatively, sensor system  64  includes at least one infrared sensor  66  for determining a size, shape, and/or position of the person&#39;s foot and/or shoe. In the exemplary embodiment, sensor  66  includes a transmitter and a receiver with an infrared beam extending therebetween. 
     If the person&#39;s foot and/or shoe intercepts the infrared beam, an alarm is indicated and/or the person is prompted to reposition the foot. As such, sensor  66  is positioned with respect to kiosk  24  such that a statistical average foot and shoe will not intercept the infrared beam. In one embodiment, sensor system  64  includes an array of sensors  66  in the shape of an outline of a statistically average foot and/or shoe such that statistically unusual feet and/or shoes will break at least one infrared beam and a statistically average foot and/or shoe will be surrounded by infrared beams. Alternatively, sensors  66  configured to sense shape and/or configuration are positioned and/or oriented in any suitable manner than enables inspection system  10  to function as described herein. In the exemplary embodiment, in addition to detecting unusual characteristics of the person&#39;s feet and/or shoes, sensors  66  configured to sense shape and/or configuration to facilitate properly and/or optimally positioning the person&#39;s feet within kiosk  24 . 
     In the exemplary embodiment of sensor  66  configured to sense shape and/or configuration, if sensor  66  detects a cubically-shaped shoe, inspection system  10  alerts security personnel such that the shoe and/or the person may be further screened. Further, an usually long and/or wide shoe may be indicative to the presence of a target material within a shoe. Accordingly, sensor system  64  facilitates detecting unusual physical characteristics of the person and/or the item on the person to determine if a target material is present and/or if the person was near a target material before entering kiosk  24 . 
       FIG. 4  is a flowchart of an exemplary embodiment of an inspection process  200  for inspecting a person that may be used with inspection system  10  (shown in  FIGS. 1-3 ) and/or with inspection system  100  (shown in  FIG. 5 ). Referring to  FIGS. 1-4 , inspection system  10  performs inspection process  200  that includes performing a position determination  202 , a verification process  204 , an explosives detection search  206 , a target material scan  208  and/or a sensor system scan  210 , in any suitable order and/or simultaneously. 
     To use inspection system  10  to screen a person, a position of person within inspection system  10  is determined  202 . More specifically, inspection system  10  determines  202  whether the person is within kiosk  24  using positioning device  60  and/or sensor system  64 . In one embodiment, determining  202  the position of the person include using sensor system  64  to determine whether at least feet of the person are properly positioned within inspection system  10 . In the exemplary embodiment, after the person&#39;s position is determined  202 , sensor system  64  determines whether the person and/or an item on the person has any unusual physical characteristics by performing  210  the sensor system scan. More specifically, as described herein, sensor system  64  determines if any statistically outlying measurements, such as temperature and/or shoe geometry, are measured by sensor  66 , as described herein. Results of the sensor system scan are output  212  by inspection system  10 . If an unusual physical characteristic is present, security personnel are alerted for further screening of the person. 
     In an alternative embodiment, after inspection system  10  has determined  202  that the person to be inspected is within kiosk  24 , inspection system  10  then prompts the person to enter identity information to perform  204  the optional verification process. For example, as discussed above, kiosk  24  may request that a person enter a registration card having the person&#39;s previously verified biometric information into electronic card reader  44 . Inspection system  10  then automatically prompts the person to place a body part onto one of the identity verification systems. For example, inspection system  10  may prompt the person to place at least one eye in front of iris scan device  46 . Inspection system  10  then determines whether the person&#39;s eye is positioned in front of iris scan device  46  and automatically initiates scanning the person&#39;s eye to produce an image of the iris as discussed above. The generated image is then compared to the biometric information stored on the person&#39;s registration card to verify the identity of the person. Alternatively, inspection system  10  automatically prompts the person to place a finger on fingerprint scan device  48  to perform  204  the verification process. Inspection system  10  then determines whether the person&#39;s finger is positioned on fingerprint scan device  48  and automatically initiates scanning the person&#39;s finger to produce an image of the fingerprint, as discussed above. The generated image is then compared to the biometric information stored on the person&#39;s registration card to verify the identity of the person. In the exemplary embodiment, results of the verification process are output  212  by inspection system  10 . If the person&#39;s identity is not verified, inspection system  10  alerts security personnel so a further screening of the person may be performed. 
     In a further alternative embodiment, after the identity of the person has been verified  204 , inspection system  10  prompts a person to perform  206  the optional explosives detection search. For example, inspection system  10  prompts the person to press her thumb on fingertip trace explosive detection system  62 . In the exemplary embodiment, fingertip trace explosive detection system  62  is configured to determined whether the person&#39;s finger is positioned on fingertip trace explosive detection system  62  and to automatically initiate a trace explosives scan on the fingertip of the person within kiosk  24  in a relatively short time period, thus decreasing the time required to inspect a person for explosives. Results of the explosives detection search are output  212  by inspection system  10 . If explosives are present, inspection system  10  alerts security personnel to perform a further search. 
     To facilitate performing  208  the optional target material scan, such as a metal scan and/or an explosives scan, of the lower leg and feet region of the person, inspection system  10  is configured to automatically prompt the person to correctly position her feet within kiosk  24 . Inspection system  10  then determines the relative location of a person&#39;s feet within inspection system  10  to verify that the person&#39;s feet are positioned within the predetermined screening area. In the exemplary embodiment, the position of the person&#39;s feet within kiosk  24  is determined using positioning device  60  described above. Once both foot are positioned correctly within the predetermined screening area, inspection system  10  automatically initiates and performs  208  the target material scan, such as a metal detection and/or explosive scan, to screen the person, as described herein. Results of the target material scan are output  212  by inspection system  10 . If a target material, such as metal and/or an explosive material, is detected during target material scan, inspection system  10  notifies security personnel for further screening of the person. 
       FIG. 5  is a flowchart of a first alternative embodiment of method  200 . More specifically,  FIG. 5  illustrates method  200  when sensor  66  is configured to determine a temperature and/or temperature gradient of and/or proximate a lower extremity of the person. In the exemplary embodiment, performing  210  the sensor system scan includes detecting  214  a temperature and/or temperature gradient of and/or proximate a lower extremity of the person after the position of the person has been determined  202 . After the temperature and/or temperature gradient is detected  214 , the detected temperature and/or temperature gradient is compared to a predetermined range, model, and/or threshold to determine  216  if the measured temperature and/or temperature gradient is unusual. If the measured temperature and/or temperature gradient is unusual, outputting  212  includes outputting  218  the results of the sensor system scan as an alert. More specifically, the alert alerts the third party that a further search and/or inspection of the person may be necessary. For example, when the alert is output  218 , a non-NQR scan is performed to detect a target material associated with the person. 
     If the measured temperature and/or temperature gradient is not unusual, inspection system  10  performs at least one of the verification process  204 , the explosives detection search  206 , and/or the target material search  208  and outputs  212  the results of the verification process  204 , the explosives detection search  206 , and/or the target material search  208 . 
       FIG. 6  is a flowchart of a second alternative embodiment of method  200 . More specifically,  FIG. 6  illustrates method  200  when sensor  66  is configured to determine a shape of and/or proximate a lower extremity of the person. In the exemplary embodiment, performing  210  the sensor system scan includes detecting  222  a shape of and/or proximate a lower extremity of the person after the position of the person has been determined  202 . After the shape is detected  222 , the detected shape is compared to a predetermined range, model, and/or threshold to determine  224  if the measured shape is unusual. If the measured shape is unusual, outputting  212  includes outputting  226  the results of the sensor system scan as an alert. More specifically, the alert alerts the third party that a further search and/or inspection of the person may be necessary. 
     If the measured temperature and/or temperature gradient is not unusual, inspection system  10  performs at least one of the verification process  204 , the explosives detection search  206 , and/or the target material search  208  and outputs  212  the results of the verification process  204 , the explosives detection search  206 , and/or the target material search  208 . 
       FIG. 7  is a flowchart of a third alternative embodiment of method  200 . More specifically,  FIG. 7  illustrates method  200  when sensor  66  is configured to determine a position of a lower extremity of the person. In the exemplary embodiment, determining  202  the position of the person includes detecting  228  a position and/or a shape of a lower extremity of the person, such as the person&#39;s foot. After the position is detected  228 , the detected position is compared to a predetermined position of the person to determine  230  if the measured position is a correct position. If the measured position is not correct, outputting  212  includes outputting  232  the results of the sensor system scan as an alert. More specifically, the alert prompts the person to reposition himself/herself within inspection system  10  and/or alerts a third party to the incorrect position of the person. The third party may assist in correctly positioning the person and/or further search and/or inspect the person. 
     If the measured position is correct, inspection system  10  performs  210  at least the sensor system scan for an unusual characteristic. The position detection  228  can be considered to be the sensor system scan performance  210  or can be considered to be separate from the sensor system scan performance  210 . For example, while sensor system  64  is detecting  228  the position, sensor system  64  can also be performing  210  the sensor system scan for a physical characteristic, such as temperature and/or shape. As such, steps  228  and  210  can be performed simultaneously by the same sensor system  64 . Results of step  228  and/or step  210  are output  212  by inspection system  10 . Further, inspection system  10  may also perform one of the verification process  204 , the explosives detection search  206 , and/or the target material search  208  and output  212  the results of the verification process  204 , the explosives detection search  206 , and/or the target material search  208 . 
       FIG. 8  is a perspective view of an alternative inspection system  100  including sensor system  64 , as described in more detail above. Inspection system  100  is a walkthrough scanner that includes a first wall  102  and a second wall  104 . Inspection system  100  is described herein as a walkthrough inspection system implemented as part of a typical aviation security system and, more particularly, as a scanner configured to scan the lower extremities and/or shoes of a person. However, it should be understood that inspection system  100  may be used to scan objects other than a person. Inspection system  100  includes an open-access entrance  106  and exit  108 , which are defined by the substantially U-shaped design of the structure of inspection system  100 . In an alternative embodiment, inspection system  100  may include gates, doors, and/or other enclosure devices at entrance  106  and/or exit  108 , for example. Details of inspection system  100  are described in U.S. Pat. No. 7,365,536, issued Apr. 29, 2008. 
     In the exemplary embodiment, inductive sensor  34 , as described in more detail above, is located within inspection system  100 . More specifically, inductive sensor  34  may be positioned within a sensor housing  110  of a walkway  112  extending between entrance  106  and exit  108 . Sensor housing  110  is also referred to herein as a recessed region although, in the exemplary embodiment, inductive sensor  34  may be mounted to a non-recessed sensor housing, mounted onto a substantially flat portion of walkway  112 , and/or be positioned with respect to first wall  102  and/or second wall  104  at any suitable location that enables inspection system  100  to function as described herein. When inductive sensor  34  is mounted to a non-recessed sensor housing, the person steps up and onto the non-recessed sensor housing for inspection. Inductive sensor  34  and/or the volume surrounding inductive sensor  34  may also be considered to be a “screening system.” In the exemplary embodiment, inductive sensor  34  is configured similarly to the QR sensor described in U.S. Pat. No. 7,365,536. 
     In the exemplary embodiment, inductive sensor  34  provides explosives screening, for example, as part of inspection system  100 , however inductive sensor  34  may be configured to cooperate with other types of inspection and detection systems, such as metal detection, vapor trace, and/or any other suitable inspection systems. For example, a QR inspection system may be integrated with a walkthrough detection portal equipped with a trace detection system. 
     In the exemplary embodiment, inspection system  100  includes sensor system  64 , described in more detail above, and is considered to be a “characteristic detection system.” More specifically, in the exemplary embodiment, each sensor  66  of an array  114  is oriented laterally such that an axis of a respective sensing zone is substantially perpendicular to a floor  116  of inspection system  100  and/or is oriented obliquely such that the axis of a respective sensing zone is oriented at an acute angle to first wall  102  and/or second wall  104 . Alternatively, the axes of sensors  66  may be oriented at any suitable angle to walls  102  and/or  104  and/or to floor  116  that enables inspection system  100  to function as described herein. In the exemplary embodiment, sensors  66  are oriented toward the person&#39;s feet and/or shoes to measure a general local temperature and/or temperature gradient of the person&#39;s feet and/or shoes. More specifically, sensors  66  are oriented and/or positioned to measure predetermined portions of the person&#39;s feet and/or shoes. 
     In an alternative embodiment, sensor system  64  includes contact temperature sensors  66  positioned on floor  116  such that the person stands on sensors  66  when positioned within inspection system  100 . More specifically, when the person stands on sensors  66 , sensor system  64  measures the temperature of the person&#39;s feet. In still another alternative embodiment, when inspection system  100  includes traffic control gates that are configured to prevent the person from proceeding to exit  108 , a second array of sensors  66  is positioned on each traffic control gate. More specifically, each sensor  66  of the second array is configured similarly to sensors  66  of second array  72  (shown in  FIG. 3 ), and each sensor  66  of array  114  is configured similarly to sensors  66  of first array  70  (shown in  FIG. 3 ). 
     Inspection system  100  performs an inspection process that includes at least a sensor system scan. More specifically, inspection  100  performs method  200  as illustrated in  FIGS. 4-7 , and described in more detail above. 
     In one example of performing an inspection process using inspection system  100 , during the inspection process of a person, the person enters inspection system  100  at entrance  106 , proceeds along walkway  112 , and stands with her feet positioned over inductive sensor  34 , within an inspection region defined to include inductive sensor  34 . More specifically, the person stands with her left foot positioned relative to a first current branch and her right foot positioned relative to a second current branch of inductive sensor  34 . Inductive sensor  34  then performs the target material scan using, in the exemplary embodiment, nuclear quadrupole resonance (NQR) to detect the presence of a target material associated with the person. Results of the target material scan are output by inspection system  100 . If a target material is detected during the target material scan, inspection system  100  alerts security personnel such that a further search of the person may be performed. In an alternative embodiment, during the target material scan, inspection system  100  uses inductive sensor  34  to additionally, or alternatively, detect metallic objects, such as guns, ice picks, knives, razors, and/or other metallic objects that may be used as weapons, present near the lower extremities of the inspected person. 
     In the exemplary embodiment, after the person is positioned within inspection system  100  in the inspection region, sensor system  64  determines whether the person and/or the item on the person has any unusual physical characteristics by performing the sensor system scan. More specifically, as described herein, sensor system  64  determines if any statistically outlying measurements, such as temperature and/or shoe geometry, are measured by sensor  66 . Results of the sensor system scan are output by inspection system  100 . If an unusual physical characteristic is present, security personnel are alerted for further screening of the person. In one embodiment, a non-NQR scan is performed if an unusual physical characteristic is present. 
     The inspection systems described herein facilitate quickly and accurately inspecting a person for a target material and/or other contraband. More specifically, by including at least an inductive sensor for detecting metal and/or explosives and a sensor system for detecting an unusual physical characteristic, multiple types of materials and/or objects can be detected within a relatively short period of time, as compared to scanning a person with separate inspections systems in series. Further, when the sensor system described herein includes a temperature sensor, performance of a QR sensor is optimized. Moreover, by detecting unusual physical characteristics of a person and/or an item on the person, the inspection systems described herein facilitate reducing a number of false negatives. For example, the embodiments described herein facilitate detecting benign objects that appear to be benign but include and/or conceal the target material. 
     A technical effect of the embodiments described herein is detecting unusual physical characteristics of a person and/or an item on the person to facilitate reducing a number of false negatives and determining whether a person has been and/or is in possession of a target material. 
     Further, the inspection systems described herein detected target materials, such as contraband and/or other items of interest located in proximity to a person&#39;s footwear, socks, trousers, and/or other apparel items present at the lower extremities. Accordingly, footwear, socks, and/or other clothing items need not be removed prior to inspection because such items can be inspected by the QR inspection system while being worn by the person. Since the inspected person is not required to remove such items before inspection, the QR inspection system is especially suited for the non-intrusive inspection of persons as part of a multi-station, airport screening checkpoint. 
     Exemplary embodiments of a method and an inspection system are described above in detail. The method and inspection system are not limited to the specific embodiments described herein, but rather, components of the inspection system and/or steps of the method may be utilized independently and separately from other components and/or steps described herein. For example, the method may also be used in combination with other screening and/or inspection systems and methods, and are not limited to practice with only the inspection system and method as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other material detection applications. 
     Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.