Abstract:
A check process may be performed without rotation of a radiation source or detector. A CT scan security check device may include a radiation source and a detector forming a radiation detection area, a conveyer mechanism conveying an article along a path, and a multidimensional movement mechanism causing a relative displacement between the article and the radiation detection area in a vertical direction and causing the article to rotate about a vertical axis. A CT scan security check method may include: 1) displacing the article relative to the radiation detection area in the vertical direction; 2) rotating the article; 3) during the checked article passing through the radiation detection area, obtaining data regarding a radiation ray that passes through the article; and 4) transmitting the data for a CT arithmetic reconstruction.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to radiation detection technology, and more particularly to a computed tomography (CT) scan security check device and method for performing a security check on baggage articles. 
       BACKGROUND INFORMATION 
       [0002]    Currently, the radiation-ray-type security check technique for baggage articles is mainly divided into an x-ray two dimension imaging technique and a CT imaging technique. As the requirement of baggage articles security check is increased, based on the prominent technical advantages of the CT imaging technique per se over the x-ray two dimension imaging technique, the importance of the CT imaging technique in baggage articles security check work is more apparent. 
         [0003]    The existing baggage articles CT imaging technique borrows ideas from medical CT technical solutions, that is, the baggage articles security check is carried out by a cooperation of a continuous rotation movement of the radiation source and the detector about a horizontal axis and a horizontal movement of the baggage articles. The medical CT imaging technique has been developed for a longer time and some mature experiences may be referred to for main relative members (such as slip ring, etc.), which provides a reliable technical guarantee for the development of baggage articles CT scan devices. However, the main relative members are required both to meet the reliability of continuous rotation and to implement the information communication of high speed and large amount data as well as the electric power support, so that the technical difficulty is large and the design and production cost is very high, thus disadvantageous to the spreading and application of the baggage articles CT imaging technique. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present invention to provide a CT scan security check device wherein the radiation source and the detector are configured not to rotate when operating. 
         [0005]    It is a further object of the present invention to provide a CT scan security check device wherein the radiation source and the detector are configured to be immovable. 
         [0006]    It is another further object of the present invention to provide a CT scan security check device wherein the radiation source and the detector are configured not to rotate and the checked article does not make a vertical lifting and lowering movement when operating. 
         [0007]    It is another further object of the present invention to provide a CT scan security check device which speeds up the check process in the case that the radiation source and the detector are configured not to rotate when operating. 
         [0008]    It is another further object of the present invention to provide a CT scan security check device which performs an automatic and continuous check on the checked article in the case that the radiation source and the detector are configured not to rotate when operating. 
         [0009]    It is another object of the present invention to provide a CT scan security check method wherein the radiation source and the detector are configured not to rotate when operating. 
         [0010]    It is a further object of the present invention to provide a CT scan security check method wherein the radiation source and the detector are configured to be immovable. 
         [0011]    It is another further object of the present invention to provide a CT scan security check method wherein the radiation source and the detector are configured not to rotate and the checked article does not make a vertical lifting and lowering movement when operating. 
         [0012]    It is another further object of the present invention to provide a CT scan security check method which speeds up the check process in the case that the radiation source and the detector are configured not to rotate when operating. 
         [0013]    It is another further object of the present invention to provide a CT scan security check method which performs an automatic and continuous check on the checked article in the case that the radiation source and the detector are configured not to rotate when operating. 
         [0014]    According to an aspect of an example embodiments, the present invention provides a CT scan security check device, comprising: a radiation source and a detector which form a radiation detection area; a conveyer mechanism which conveys a checked article along a conveying path; and a multidimensional movement mechanism which makes the checked article and the radiation detection area generate a relative displacement in a vertical direction and makes the checked article rotate about a vertical axis. 
         [0015]    In an embodiment in accordance with the present invention, the multidimensional movement mechanism comprises a rotation mechanism disposed in the conveying path and operatively making the checked article rotate after the checked article is conveyed to the rotation mechanism by the conveyer mechanism; and a vertically lifting and lowering mechanism which makes the checked article conveyed to the rotation mechanism generate a relative movement in the vertical direction to the radiation detection area. 
         [0016]    In a further embodiment in accordance with the present invention, the radiation source and the detector are mounted to the vertically lifting and lowering mechanism. 
         [0017]    In another further embodiment in accordance with the present invention, the rotation mechanism is rotatably mounted on the vertically lifting and lowering mechanism. Further, the radiation source and the detector are mounted to a radiation protection shield of the CT scan security check device; or alternatively, the CT scan security check device further comprises a secondary vertically lifting and lowering mechanism, and the radiation source and the detector are mounted to the secondary vertically lifting and lowering mechanism. 
         [0018]    The vertically lifting and lowering mechanism comprises a load-bearing platform and a vertically lifting and lowering electromotor to drive the load-bearing platform to move in the vertical direction. 
         [0019]    The rotation mechanism comprises: a support plate rotatably mounted on the load-bearing platform; a plurality of support rollers mounted on the support plate which rotate together with the support plate and bring the checked article to rotate after the checked article is conveyed on the plurality of support rollers by the conveyer mechanism; and a rotation electromotor mounted within an internal cavity of the load-bearing platform and operatively driving the support plate to rotate about the vertical axis. 
         [0020]    The plurality of support rollers are configured to be locked when the checked article is wholly conveyed thereonto, and to rotate to convey the checked article in a horizontal direction out from the rotation mechanism after the CT scan of the checked article is completed. 
         [0021]    On the support plate is mounted at least one sensor to detect whether or not the checked article is wholly conveyed onto the plurality of support rollers. 
         [0022]    In a further embodiment in accordance with the present invention, the conveyer mechanism comprises a conveying-in mechanism and a conveying-out mechanism located respectively on both sides of the multidimensional movement mechanism in the conveying path. 
         [0023]    Further, a conveying-out port of the conveying-in mechanism is at a height identical to a conveying-in port of the conveying-out mechanism; and the conveying-in mechanism and the conveying-out mechanism are preferably conveyer belt mechanisms of which the conveying directions are configured to be horizontal. Or alternatively, there is a height difference between a conveying-out port of the conveying-in mechanism and a conveying-in port of the conveying-out mechanism, and the height difference is configured to at least equal to a vertical travel distance of the vertically lifting and lowering mechanism in a check process; and at least one of the conveying-in mechanism and the conveying-out mechanism is preferably a conveyer belt mechanism of which the conveying direction is configured to be inclined. 
         [0024]    According to another aspect of example embodiments, the present invention provides a CT scan security check method, comprising the following steps: 1) causing the checked article and the radiation detection area to generate a relative displacement in a vertical direction and causing the checked article to perform a rotation movement; 2) during the checked article passing through the radiation detection area, obtaining information data on the radiation ray through the checked article; and 3) transmitting out the information data for CT arithmetic reconstruction. 
         [0025]    Further, in step 1): the checked article performs a vertical lifting and lowering movement and a rotation movement, and the radiation detection area is stationary; or alternatively the checked article performs a rotation movement, and the radiation detection area performs a vertical movement; or alternatively the checked article performs a vertical lifting and lowering movement and a rotation movement, and the radiation detection area performs another vertical lifting and lowering movement. 
         [0026]    Further, the CT scan security check method comprises the following steps: conveying the checked article to a check position prior to step 1); and/or conveying the checked article away from the check position after step 3). 
         [0027]    According to example embodiments of the present invention, due to adopting the technical solution of making the checked article and the radiation detection area generate a relative displacement in a vertical direction and making the checked article perform a rotation movement, it can be achieved to perform a CT-scan-security-check on the checked article without the rotation of the radiation source and the detector, reducing the technical difficulty and design and production cost of CT-scan-security-check. Example embodiments of the present invention further provide an automatic conveyer mechanism and necessary sensors so that the checked article can be checked automatically and continuously, and provide a secondary vertically lifting and lowering mechanism for the radiation source and the detector, speeding up the procedure of CT scan security check. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a horizontal sectional view of a CT scan security check device in accordance with a first embodiment of the present invention where an upper portion of the radiation protection shield is cut away to show an internal structure of the CT scan security check device. 
           [0029]      FIG. 2  is a longitudinal sectional view of the CT scan security check device of  FIG. 1 . 
           [0030]      FIG. 3  is a left view of the CT scan security check device of  FIG. 1  (a vertically lifting and lowering mechanism below the conveyer mechanism is omitted in  FIG. 3 ). 
           [0031]      FIG. 4  is a structural schematic view of a CT scan security check device in accordance with a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    The present invention will be described in detail with reference to embodiments and accompanying drawings to make the technical solution of the present invention clearer. 
         [0033]    As shown in  FIG. 1 , a CT scan security check device  100  in accordance with a first embodiment of the present invention comprises generally a radiation source  20  and a detector  30  which form a radiation detection area, and a conveyer mechanism  10  which conveys a checked article  70  along a conveying path A. The radiation detection area is schematically shown by two dash dot lines in  FIG. 1 . 
         [0034]    The radiation source  20  may be generally one or more x-ray sources or isotope sources of which the energy is configured to be adjustable. The detector  30  may be a one-dimensional detector array or two-dimensional detector array, and these detector arrays may be a single-layer structure or a multi-layer structure. As well known by those skilled in the art, the shape of the radiation detection area depends on the form or type of the adopted detector. If the detector adopts a rectangular two-dimensional detector array, the radiation beam should be reshaped into a rectangle by means of a collimator; and if the detector adopts a one-dimensional linear detector, the radiation beam should be reshaped into a linear shape by means of a collimator. 
         [0035]    Particularly, the CT scan security check device  100  also comprises a multidimensional movement mechanism  80  which causes the checked article  70  and the radiation detection area to generate a relative displacement in a vertical direction and causes the checked article  70  to rotate about a vertical axis. Generally, the position of the multidimensional movement mechanism  80  in the conveying path A is herein referred to as a “check position.” It will be appreciated for those skilled in the art that the check position is in the conveying path A in the radiation detection area, and is under or over the radiation detection area. 
         [0036]    Further, as shown in  FIG. 2 , the multidimensional movement mechanism  80  comprises a rotation mechanism  50  and a vertically lifting and lowering mechanism  60 . The rotation mechanism  50  is disposed in the conveying path A of the conveyer mechanism  10 , and after the checked article  70  is conveyed to the rotation mechanism  50  by the conveyer mechanism  10 , the rotation mechanism  50  operatively makes the checked article  70  rotate and the vertically lifting and lowering mechanism  60  makes the checked article  70  conveyed to the rotation mechanism  50  generate a relative movement in the vertical direction to the radiation detection area. 
         [0037]    It should be noted that such a description or definition of a feature or mechanism being “in the conveying path” or “on the conveying path” includes locating the feature or mechanism in or on extended line(s) of the conveying path or connecting line(s) between several segments of the conveying path (since the extended line(s) of the conveying path or the connecting line(s) between several segments of the conveying path may be generally viewed as part of the conveying path), as easily understood by those skilled in the art. 
         [0038]    In some embodiments of the present invention, the conveying path A may be divided into two segments, the first segment being a conveying-in path by which the conveyer mechanism  10  conveys the checked article  70  onto the rotation mechanism  50  and the second segment being a conveying-out path by which the conveyer mechanism  10  receives the CT scanned checked article  70  from the rotation mechanism  50  and conveys it out. The rotation mechanism  50  may be deposed in a connecting line between the conveying-in path and the conveying-out path. The conveying-in path and the conveying-out path are generally in line. Alternatively, it is also possible to arrange the conveying-in path and the conveying-out path so that their projections in a horizontal plane or in a vertical plane form a certain angle, which may be useful in some applications. 
         [0039]    In a preferable embodiment of the present invention, the rotation mechanism  50  is rotatably mounted on the vertically lifting and lowering mechanism  60 . The radiation source  20  and the detector  30  may be connected with each other by rigid member(s), and for example, they may be mounted to a radiation protection shield  40  of the CT scan security check device  100 . 
         [0040]    Now referring to  FIG. 3 , the radiation source  20  is mounted on one side of the radiation protection shield  40 , and the detector  30  is mounted on the other side of the radiation protection shield  40  opposite to the radiation source  20 . The sectional shape of the radiation protection shield  40  may be generally configured into an approximately inverse U-shape or any other suitable shapes, such as a half-circle shape. 
         [0041]    Referring to  FIG. 2  again, the vertically lifting and lowering mechanism  60  comprises a load-bearing platform  61  and a vertically lifting and lowering electromotor  65  driving the load-bearing platform  61  to move in the vertical direction. It should be noted that the term “driving” or “drive” used herein includes the meanings of “directly driving” or “indirectly driving via other transmission mechanisms.” For example, in this embodiment, between the vertically lifting and lowering electromotor  65  and the load-bearing platform  61  is preferably provided a threaded spindle and nut mechanism including a threaded spindle  62 , and the load-bearing platform  61  is fixed on the top of the threaded spindle  62 . In other words, the vertically lifting and lowering electromotor  65  directly or indirectly drives a nut (not shown in the drawings), which then cause the threaded spindle  62  fitting with the nut to move in the vertical direction to bring the load-bearing platform  61  to move in the vertical direction. 
         [0042]    The rotation mechanism  50  comprises a support plate  52 , a plurality of support rollers  53  and a rotation electromotor  55 . The support plate  52  is rotatably mounted on the load-bearing platform  61  of the vertically lifting and lowering mechanism  60  and can move in the vertical direction along with the load-bearing platform  61 . The rotation electromotor  55  is mounted in an internal cavity of the load-bearing platform  61 , operatively driving the support plate  52  to rotate about the vertical axis. Preferably, the rotation electromotor  55  is mounted at the upper portion of the internal cavity of the load-bearing platform  61 . 
         [0043]    The support rollers  53  are mounted on the support plate  52 . After the checked article  70  is wholly conveyed onto the support rollers  53 , the support rollers  53  are locked and no longer rotate about their pivot axes. Of course, the support rollers  53  can rotate together with the support plate  52  about the vertical axis and carry the checked article  70  to rotate. The support rollers  53  are configured to actively rotate after the CT scan on the checked article  70  is completed, in order to convey the checked article  70  out in the horizontal direction away from the rotation mechanism  50 . Preferably, the support plate  52  is configured such that: before the support plate  52  begins to be rotated, its angle position is oriented such that the pivot axes of the support rollers  53  are perpendicular to the conveying-in path; and after the CT scan is completed, the angle position is oriented such that the pivot axes of the plurality of support rollers  53  are perpendicular to the conveying-out path when the support plate  52  stops to rotate. 
         [0044]    Any suitable means may be adopted to detect whether or not the checked article  70  is wholly conveyed onto the support rollers  53 . By way of example, this detection may be achieved by providing at least one sensor  54  on the support plate  52 . Once a certain signal arises in the at least one sensor  54 , a control system of the CT scan security check device can control the support rollers  53  to stop rotating and be locked in order to ensure the checked article remains stationary relative to the support rollers  53 ; and after the CT scan is completed, the control system sends a rotation signal to the support rollers  53 , and the support rollers  53  are rotated to convey out the checked article  70  along the horizontal direction. 
         [0045]    The sensors  54  are preferably weight sensors which can automatically sense whether the checked article is already conveyed onto the rotation mechanism  50  (i.e., whether the checked article is conveyed onto the support rollers  53 ). In particular, two weight sensors may be provided respectively at suitable positions on the support plate  52  near to a conveying-in mechanism  12 , and another two weight sensors may be provided respectively at suitable positions on the support plate  52  near to a conveying-out mechanism  14 . In this way, by means of a series of logic relations easily configured, it can be detected whether or not the checked article  70  is wholly conveyed onto the support rollers  53 , and preferably whether or not the checked article  70  is conveyed in the centre of the rotation mechanism  50 . For example, assuming that the distance between the two groups of sensors is L (the length of the checked article  70  is less than the distance L), based on the signaling interval of the first group of sensors and the rotation speed of the support rollers, the time period from after no signal arises in the first group of sensors to before the support rollers  53  stops to rotate and be locked can be calculated, such that the checked article  70  is just conveyed in the center of the support plate  52 . Similarly, based on the signaling interval of the second group of sensors it can be detected whether or not the checked article  70  wholly departs away from the support rollers  53  or the rotation mechanism  50 . It should be appreciated by those skilled in the art that it is possible to adopt position sensors to perform such detection. 
         [0046]    The conveyer mechanism  10  may comprise the conveying-in mechanism  12  and the conveying-out mechanism  14  which are respectively located on both sides of the multidimensional movement mechanism  80  in the conveying path A. The conveying-out port of the conveying-in mechanism  12  extends into the radiation protection shield  40  so as to convey the checked article  70  into the radiation protection shield  40  and further convey it onto the support rollers  53  of the support plate  52 . The conveying-in port of the conveying-out mechanism  14  is also located in the radiation protection shield  40  so as to receive the checked article  70  conveyed from the support rollers  53  of the support plate  52 , and to convey the checked article  70  away from the radiation protection shield  40  after the check is completed. 
         [0047]    In the CT scan security check device  100 , the conveying-out port of the conveying-in mechanism  12  is at a height identical to the conveying-in port of the conveying-out mechanism  14 , and the conveying-in mechanism  12  and the conveying-out mechanism  14  are preferably conveyer belt mechanisms of which the conveying directions are configured to be horizontal. 
         [0048]    When using the CT scan security check device  100  to take a check, the radiation source  20  and the detector  30  are generally first set to the operating state to form the radiation detection area; then the checked article  70  is placed on the conveying-in mechanism  12  at the input port and conveyed onto the rotation mechanism  50  by the conveying-in mechanism  12 . Once the checked article  70  is conveyed onto the support rollers  53  on the support plate  52 , the sensor  54  can automatically sense it, and then the support rollers  53  are locked to make the checked article  70  stationary on the support rollers  53  and the rotation mechanism  50  bring the checked article  70  to rotate. The vertically lifting and lowering electromotor  65  of the vertically lifting and lowering mechanism  60  drives the nut to rotate, and the nut in turn drives the threaded spindle  62  and further drives the load-bearing platform  61  which carries the rotation mechanism  50  to perform the vertical lifting and lowering movement so as to complete the CT scan process. After the CT scan process is completed, the rotation mechanism  50  and the lifting and lowering mechanism  60  come back to their initial states, then the support rollers  53  on the rotation mechanism  50  automatically rotate to convey the checked article  70  onto the conveying-out mechanism  14 , and then the conveying-out mechanism  14  conveys the checked article away from the CT scan security check device  100 . The above-mentioned action processes can be controlled and completed by means of existing circuits. 
         [0049]    Now referring to  FIG. 4 , the structure of a CT scan security check device  200  in accordance with a second embodiment of the present invention is substantially identical to that of the first embodiment of the present invention. But in the CT scan security check device  200 , there is a height difference between the conveying-out port of the conveying-in mechanism  12  and the conveying-in port of the conveying-out mechanism  14 . The height difference is configured to at least equal a vertical travel distance of the vertically lifting and lowering mechanism  60  in a check process. Particularly, at least one of the conveying-in mechanism  12  and the conveying-out mechanism  14  is a conveyer belt mechanism of which the conveying direction is configured to be inclined. More particularly, the conveying-in mechanism  12  is a conveyer belt mechanism of which the conveying direction is configured to be inclined upwards, and the conveying-out mechanism  14  is a conveyer belt mechanism of which the conveying direction is configured to be horizontal, wherein the position of the conveying-out port of the conveying-in mechanism  12  is above that of the conveying-in port of the conveying-in mechanism  12 . It should be appreciated for those skilled in the art that this arrangement form of the conveying-in mechanism  12  and the conveying-out mechanism  14  allows the check on the checked article to be completed with only one lifting or lowering movement, increasing the checking efficiency. 
         [0050]    Further, in the CT scan security check devices of the present invention, a secondary vertically lifting and lowering mechanism (not shown in the drawings) may be provided for the radiation source  20  and the detector  30 . In this way, the checked article performs a vertical lifting and lowering movement along with the vertically lifting and lowering mechanism  60 , and the radiation source  20  and the detector  30  perform another vertical lifting and lowering movement along with the secondary vertically lifting and lowering mechanism, which not only is advantageous to expedite the scan speed, but also is particularly advantageous in some applications where it is inconvenient to perform a larger travel distance of vertical lifting and lowering movement on the checked article. 
         [0051]    In the embodiments described above, the checked article performs separately a lifting and lowering movement and a rotation movement by the action of the vertically lifting and lowering mechanism and the rotation mechanism, so as to pass through the radiation detection area and complete the CT scan. But according to another alternative embodiment of the present invention, the radiation source  20  and the detector  30 , rather than the rotation mechanism  50 , may be mounted to the vertically lifting and lowering mechanism  60 . In this way, the conveyer mechanism  10 , the rotation mechanism  50  and the vertically lifting and lowering mechanism  60  of the present invention are independent to each other (in other words, these mechanism may perform their respective movements independently to each other). The checked article  70  is conveyed onto the rotation mechanism  50  by the conveyer mechanism  10 , cooperating with the vertical lifting and lowering movement of the radiation source  20  and the detector  30  driven by the vertically lifting and lowering mechanism  60  so that the radiation detection area passes through the rotating checked article to realize the CT scan of the article. Such an alternative embodiment is particularly advantageous in some applications where it is inconvenient to perform a larger travel distance of vertical lifting and lowering movement on the checked article. 
         [0052]    According to another aspect, the present invention provides a CT scan security check method. The devices to perform the check method comprise but are not limited to the CT scan security check devices provided by the present invention. When using the method to perform a security check, the checked article may be firstly conveyed to the check position. Then, the checked article and the radiation detection area are made to generate a relative displacement in a vertical direction, and the checked article per se is made to perform independently a rotation movement. In particular, the checked article performs a vertical lifting and lowering movement and a rotation movement, and the radiation detection area is stationary; or the checked article performs a rotation movement, and the radiation detection area performs a vertical movement; or the checked article performs a vertical lifting and lowering movement and a rotation movement, and the radiation detection area performs another vertical lifting and lowering movement. 
         [0053]    During passing of the checked article through the radiation detection area, the information data on the radiation ray through the checked article is obtained and then transmitted out for CT arithmetic reconstruction. Then, the checked article may be conveyed away from the check position as desired. Such steps are well-known or easily achieved for those skilled in the art and are not described in detail herein for purposes of simplicity. 
         [0054]    The foregoing exemplary embodiments are illustrative of the present invention and are not to be construed as limiting thereof. Those skilled in the art will readily appreciate that many modifications, alternatives and equivalents are possible in the exemplary embodiments without departing from the spirit and scope of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. For example, the inventive concepts may be applied to some radiation ray scan security-check device or method which synthetically adopts an x-ray two-dimensional imaging technique and a CT imaging technique. Again for example, the transmission mechanisms such as gear-rack mechanism, cam-lifter mechanism, crank-slider mechanism and the like may be adopted or some linear motor may be directly adopted so as to alternatively achieve the vertically lifting and lowering mechanism. Therefore, the protection scope of the present invention is intended to be defined by the claims appended hereto and their equivalents, and all modifications, alternatives and equivalents of the exemplary embodiments should be included in the scope of the present invention.