Abstract:
An apparatus for reading out x-ray information stored in a storage phosphor plate includes an input device having a slot through which a cassette is inserted into the input device, the cassette configured to accommodate a storage phosphor plate, therein, and a read-out device that irradiates the storage phosphor plate with stimulation light and detecting emission light stimulated by the phosphor plate. The input device receives cassettes having different cassette widths, and the input device includes one or more first elements that align and/or fix the cassettes having different cassette widths in the input device, and/or one or more second elements that close the slot of the input device in order to prevent ambient light from passing through the slot when cassettes having different cassette widths are inserted into the input device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a 371 National Stage Application of PCT/EP2014/074392, filed Nov. 12, 2014. This application claims the benefit of European Application No. 13194600.6, filed Nov. 27, 2013, which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus and a method for reading out x-ray information stored in a storage phosphor plate. 
         [0004]    2. Description of the Related Art 
         [0005]    One possibility for recording X-ray images is to store X-ray radiation passing through an object, for example a patient, as a latent image in a so-called storage phosphor layer. In order to read out the latent image the storage phosphor layer is irradiated with stimulation light and thereby stimulated to emit emission light. The emission light, the intensity of which corresponds to the image stored in the storage phosphor layer, is detected by an optical detector and converted into electrical signals. Furthermore, the electrical signals are processed as required and finally made available for analysis, in particular for medical and/or diagnostic purposes, by being displayed on an appropriate display device, such as e.g. a monitor or printer. 
         [0006]    EP 2 573 616 A1 shows an according read-out apparatus comprising an input device for receiving a cassette accommodating a storage phosphor plate. When the cassette is inserted into the input device, the cassette is fixed in the input device and/or opened by mechanically driven elements. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide an apparatus and an according method allowing for reading out storage phosphor plates accommodated in cassettes of at least two different formats. 
         [0008]    These objects are achieved by the method and the system defined below. 
         [0009]    An apparatus for reading out x-ray information stored in a storage phosphor plate comprises an input device having a slot through which a cassette can be inserted into the input device, the cassette being designed for accommodating a storage phosphor plate, and a read-out device for irradiating the storage phosphor plate with stimulation light and detecting emission light stimulated in the phosphor plate. According to a preferred aspect of the invention, the input device is designed for receiving cassettes having different cassette widths, wherein the input device comprises one or more first elements designed for aligning and/or fixing cassettes having different cassette widths in the input device and/or one or more second elements designed for shutting the slot of the input device in order to prevent ambient light from passing through the slot when cassettes having different cassette widths are inserted into the input device. 
         [0010]    A method for reading out x-ray information stored in a storage phosphor plate comprises the steps of inserting a cassette into an input device through a slot of the input device, the cassette being designed for accommodating a storage phosphor plate, and reading out the storage phosphor plate by irradiating the storage phosphor plate with stimulation light and detecting emission light stimulated in the phosphor plate. According to a preferred aspect of the invention, the method further comprises the steps of aligning and/or fixing cassettes, which have different cassette widths, in the input device by one or more first elements and/or shutting the slot of the input device by one or more second elements in order to prevent ambient light from passing through the slot when cassettes having different cassette widths are inserted into the input device. 
         [0011]    Preferably, the term “cassette width” relates to the dimension of a cassette along a direction which is essentially parallel to the extension of an opening of the cassette through which the storage phosphor plate can be removed from the cassette. Additionally or alternatively, the term “cassette width” may relate to the dimension of a cassette along a direction which is essentially perpendicular to the direction in which the cassette is inserted into the input unit. Additionally or alternatively, the term “cassette width” may relate to the dimension of a cassette along a direction which is essentially parallel to the extension of the slot of the input device. 
         [0012]    Preferred embodiments of the invention are based on the approach to provide an input device into which cassettes having different cassette widths can be inserted. First elements for aligning and/or fixing a cassette in the input unit and/or second elements for shutting a section of the slot, which is not “covered” or “occupied” with the inserted cassette of a given cassette width, are preferably arranged such that for each cassette width of the cassettes, which can be inserted into the input device, specific or corresponding first and/or second elements are provided. For example, for aligning and/or fixing a cassette having a first cassette width first and/or second elements having a first position and/or first design are provided, whereas for aligning and/or fixing a cassette having a second cassette width, which is e.g. larger than the first cassette width, first and/or second elements having a second position and/or second design are provided. Same applies accordingly for first and/or second elements provided for cassettes having a third, fourth, fifth etc. cassette width. According to a particularly preferred aspect of the invention, the first and/or second elements comprise mechanical elements, which are driven by a pure mechanical drive, i.e. driven, e.g., without electromechanical devices like motors. 
         [0013]    In summary, preferred embodiments of the invention allow for reading out storage phosphor plates accommodated in cassettes of at least two different formats. 
         [0014]    Preferably, the first elements comprise at least one aligning element for each of the at least two different cassette widths, wherein each of the at least one aligning elements is designed for aligning and/or fixing a cassette of a given cassette width in the input device. For example, each of the aligning elements is designed for being pressed against a side face of the cassette, whereby the cassette is advanced by the aligning element along a direction parallel to the extension of the slot and/or pressed against an end stop provided at the opposite side face of the cassette. 
         [0015]    In particular, the first elements further comprise at least one end stop, in particular a side end stop, and each of the at least one aligning elements being positioned such that when a cassette of a first cassette width is inserted, the cassette is pressed against the end stop by a first aligning element having a first position, and when a cassette of a second cassette width is inserted, the cassette is pressed against the end stop by a second aligning element having a second position, which is different from the first position. In particular, the distance between the first and the second position of the first and second aligning element approximately corresponds to the difference between the first and the second cassette width. 
         [0016]    It is particularly preferred that the first and second aligning elements are provided at different positions along a first direction running parallel to the extension of the slot of the input device and/or parallel to the extension of the opening of a cassette inserted into the slot. 
         [0017]    It is, moreover, preferred that the first and second aligning elements are mounted on a first mounting element, e.g. a rod-like element. Preferably, the first and/or second aligning elements are pivotably mounted on the first mounting element. 
         [0018]    In another preferred embodiment the apparatus further comprises a first guiding element arranged and/or formed for interacting with the first mounting element, whereby the first mounting element can be shifted parallel to the first direction. Preferably, the first guiding element is, preferably rigidly, mounted on a base of the input device. 
         [0019]    In yet another preferred embodiment the apparatus further comprises a carrier designed for being displaced, preferably relative to the base of the input device, in a second direction, which is perpendicular to the first direction, by a cassette being inserted into the input device. The first mounting element is provided, preferably mounted, on the carrier such that when the carrier is displaced in the second direction the first mounting element moves relative to the first guiding element and is therefore interacting with the latter. Preferably, the first guiding element is wedge-shaped such that when the first mounting element, in particular a mounting rod, is moved in the second direction relative to the wedge-shaped guiding element, the former is shifted or advanced parallel to the first direction. 
         [0020]    According to a further preferred embodiment of the invention, the second elements comprise at least one cover element for each of the at least two different cassette widths, wherein each of the at least one cover element is designed for shutting the slot of the input device when a cassette of a given cassette width is inserted in the input device. 
         [0021]    In particular, each of the at least one cover elements being positioned such that when a cassette of a first cassette width is inserted, the slot is shut by a first cover element having a first position and a second cover element having a second position, which is different from the first position, and when a cassette of a second cassette width is inserted, the slot is shut by the second cover element. 
         [0022]    In yet another preferred embodiment the first and second cover elements are provided at different positions along a first direction parallel to the extension of the slot of the input device and/or to the extension of the opening of a cassette inserted into the slot. 
         [0023]    It is further preferred that the first and second cover elements are mounted on a second mounting element. Preferably, the first and/or second cover elements being pivotably mounted on the second mounting element. For example, the second mounting element may be a rod-like mounting element. 
         [0024]    Preferably, a carrier is provided which is designed for being displaced in a second direction, which is perpendicular to the first direction, by a cassette being inserted into the input device. 
         [0025]    It is, moreover, preferred that the apparatus further comprises a second guiding element arranged and/or formed for interacting with the second mounting element, such that the second mounting element is shifted parallel to the first direction, whereby the first and/or second cover element is/are pressed against the inserted cassette. In particular, the second guiding element is, in particular rigidly, mounted on the carrier and/or rigidly coupled with the carrier. 
         [0026]    It is, moreover, preferred that the second mounting element is provided on the carrier such that when the carrier is displaced in the second direction the second mounting element is interacting with the second guiding element so that the second mounting element is shifted or advanced parallel to the first direction, whereby the first and/or second cover element is/are moved towards and/or pressed against the inserted cassette. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Further advantages, aspects and examples of the present invention will be apparent from the description of following figures: 
           [0028]      FIG. 1  shows an example of a read-out device for reading out a storage phosphor plate. 
           [0029]      FIG. 2  shows a cross section of an example of an apparatus for reading out storage phosphor plates. 
           [0030]      FIG. 3  shows a perspective view of an example of an input device. 
           [0031]      FIG. 4  shows a perspective view of the input device in a first state together with an inserted cassette of a first format. 
           [0032]      FIG. 5  shows a perspective view of the input device in a second state together with the inserted cassette of the first format. 
           [0033]      FIG. 6  shows a perspective view of the input device in a first state together with an inserted cassette of a second format. 
           [0034]      FIG. 7  shows a perspective view of the input device in a second state together with the inserted cassette of the second format. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]      FIG. 1  shows a read-out device for reading out a storage phosphor plate  1 . By a laser  2  a stimulation light beam  3  is generated, which is deflected by a deflector  4  such that the deflected beam  3 ′ moves along a line  8  over the storage phosphor plate  1 . The deflector  4  has a reflective surface, in particular in the form of a mirror, which is caused to oscillate by a driving device  5 . Alternatively, the deflector  4  may be a polygon mirror which is rotated by the driving device  5 , e.g. a motor. 
         [0036]    During the movement of the deflected stimulation light beam  3 ′ over the storage phosphor plate  1  the latter emits, as a function of x-ray information stored therein, emission light which is collected by an optical collector  6 , for example a light guide and/or a fiber bundle, detected by an optical detector  7 , preferably a photomultiplier tube (PMT) and thereby converted into a corresponding detector signal S which is supplied to a processing device  9 , in which digital image signal values B for individual pixels of the read-out x-ray image are derived. 
         [0037]    Due to conveying the storage phosphor plate  1  in a transport direction T by a transport device, individual lines  8  of the storage phosphor plate  1  are successively read out and thus a two-dimensional x-ray image made up of individual pixels with associated image signal values B is obtained. The transport device preferably comprises a roller  10  which is rotated about a rotational axis  11  by a respective roller drive (not shown) and conveys the storage phosphor plate  1 , preferably due to frictional and/or magnetic forces between the storage phosphor plate  1  and the roller  10 . 
         [0038]      FIG. 2  shows a cross section of an apparatus  12  for reading out storage phosphor plates. The apparatus  12  comprises a housing  13  in which a read-out device, like the one exemplarily shown in  FIG. 1 , is provided. 
         [0039]    An input device  20  is provided in a front portion of the housing  13  of the apparatus  12 , into which a cassette  40  accommodating a phosphor plate  1  can be inserted by an operator. In the given example, the insertion of the cassette  40  occurs in a substantially horizontal direction. Alternatively, it is also possible to provide the input device  20  at a different location of the housing  13 , for example at the top or in a transition region between the top and the front portion of the housing  13 . In such cases, the cassette  40  is inserted into the input device  20  along a vertical or inclined direction, respectively. 
         [0040]    In the vicinity of the input device  20  inside the housing  13  a removal device  14  is provided, which is designed for taking the storage phosphor plate  1  out of the cassette  40  and forwarding same along transport direction T to the roller  10  of the read-out device. Further, the removal device  14  is designed for feeding the storage phosphor plate  1  into the cassette  40  after it has been read out. 
         [0041]      FIG. 3  shows a perspective view of an example of an input device  20  comprising a base  21  and a carrier  22  which is movably mounted on the base  21 , preferably by guide rails  23  and  24 , such that the carrier  22  can be moved along the x-direction. Preferably, the carrier  22  is biased, for example by coil springs or leaf springs, such that it is automatically reset into an initial position near a front part  25  of the input device  20 . 
         [0042]    In the front part  25  a slot  26  extending along the y-direction is provided. The slot  26  is arranged and/or formed such that a cassette (not shown) can be inserted through the slot  26  and positioned on the carrier  22  located behind and near the slot  26 . 
         [0043]    In the case shown in  FIG. 3 , where no cassette has been inserted into the input device  20 , the slot  26  is preferably covered by cover elements  31  to  33  which are pivotably mounted on a common mounting element  34 , for example a mounting rod. The mounting element  34  interacts with a guiding element  35  which is preferably coupled with the carrier  22  such that moving the carrier  22  in the x-direction results in an according movement of the guiding element  35  relative to the mounting element  34 . Preferably, the mounting element  34  is biased, e.g. by a coil spring, against the guiding element  35 . 
         [0044]    Moreover, aligning elements  36  and  37  are provided which are pivotably mounted on a common mounting element  38 , preferably a mounting rod, which interacts with a guiding element  39 . In distinction to the guiding element  35 , the guiding element  39  is preferably coupled with the base  21  such that when the carrier  22  is moved relative to the base  21  along the x-direction, the mounting element  38  moves relative to the guiding element  39 . 
         [0045]    In the following, the functioning of the input device  20  will be explained in more detail with reference to  FIGS. 4 to 7 . 
         [0046]      FIG. 4  shows a perspective view of the input device  20  in a first state together with an inserted cassette  40  of a first format. The cassette  40  has the form of a flat rectangular prism on which an opening is provided at one of the narrow front sides. In order to shut the opening, which preferably extends over the whole width of the respective narrow front side, a hinged cassette lid  41  is provided. The front side, at which the opening and the cassette lid  41  are provided, corresponds to the leading front side with which the cassette  40  is inserted into the input device  20  and is also referred to as “opening side”. The cassette  40  has a cassette width d 1 , preferably extending along the y-direction, and a cassette length, preferably extending along the x-direction. Typical cassette widths the input unit  20  is designed for are 24 cm, 30 cm and 35 cm. 
         [0047]    In the shown first state of the input device  20 , the cassette  40  has been inserted through slot  26  of front part  25  until the leading face of the cassette  40 , on which the cassette lid  41  is provided, reaches carrier stop end  27  provided at the carrier  22 . When passing the slot  26 , a first cover element  31  is tilted upwards into a position shown in the figure, whereas second and third cover element  32  and  33  remain in a vertical position in which they cover the most part of the remaining slot  26  being adjacent to the cassette  40 . 
         [0048]    Regarding the remaining components of the input device  20 , the above-mentioned remarks with reference to  FIG. 3  apply accordingly. 
         [0049]      FIG. 5  shows a perspective view of the input device  20  in a second state together with the inserted cassette  40  of the first format. In distinction to the first state shown in  FIG. 4 , the cassette  40  has been pushed in x-direction, whereby the carrier  22  moved along with the cassette  40  until base end stops  28  and  29  provided at the base  21  are reached. Because guiding element  35  is, preferably rigidly, coupled with the moving carrier  22 , the guiding element  35  is moved relative to the mounting rod  34  of cover elements  31  to  33 . An elevated section of the guiding element  35  interacts with the mounting rod  34  such that the biased mounting rod  34  is urged along the y-direction so that the second and third cover elements  32  and  33  are moved towards the narrow side of the cassette  40  such that the remaining section of the slot  26 , which is not covered by the cassette  40 , is light-tightly shut by the cover elements  32  and  33 . 
         [0050]    Moreover, the biased mounting rod  38 , which is preferably rigidly coupled with the carrier  22 , has moved together with the movement of the carrier  22  in the x-direction and interacted with guiding element  39 , which is preferably rigidly coupled with the base  21 , whereupon the mounting rod  38  was advanced in parallel to the y-direction. By this structure, the first aligning element  36  mounted on the mounting rod  38  was pressed against the side face of cassette  40  such that the cassette  40  is advanced in parallel to the y-direction and/or pressed against a side end stop  30  which is provided on the carrier  22  at the opposite side face of the cassette  40 . In this way, an alignment and/or fixing of the cassette  40  are effected. Preferably, in the shown second state the cassette lid  41  is opened by appropriate opening elements, like hook-shaped elements as shown in EP 2 573 618 A1. 
         [0051]      FIG. 6  shows a perspective view of the input device  20  in a first state together with an inserted cassette  40  of a second format. In this example, the dimension of the cassette  40  at the side end of the opening corresponds to a width d 2  being larger than the width d 1  of the cassette  40  shown in  FIGS. 4 and 5 . 
         [0052]    As a result, by inserting the cassette  40  of the larger format into the input device  20  not only the first cover element  31  but also the second cover element  32  is tilted up, whereas the third cover element  33  remains in its vertical position. Moreover, the first aligning element  36  which is pivotably mounted on mounting rod  38  is tilted up when the leading face of the cassette comes into contact with the lower part of the hook-shaped first aligning element  36  while the cassette  40  is being moved in the x-direction until carrier stop end  27  is reached. 
         [0053]    Regarding the functioning of the remaining components of the input device  20  shown in  FIG. 6 , the above-mentioned remarks with reference to the example shown in  FIG. 4  apply accordingly. 
         [0054]    Like with the example shown in  FIG. 5 , the cassette  40  of the second format has been, preferably manually, pushed into the input device  20  parallel to the x-direction, whereby the carrier  22  is moved along with the movement of the cassette  40  until base end stops  28  and  29  are reached. 
         [0055]    During the movement of the carrier  22  in the x-direction, the guiding element  35  coupled with the carrier  22  is moved relative to the biased mounting rod  34 , whereby the latter was pushed parallel to the y-direction, when interacting with the elevated portion of the guiding element  35 . As a result, the third cover element provided on the mounting rod  34  is advanced towards the side face of the cassette  40  and is finally pressed against it such that the remaining portion of the slot  26  at the front part  25  is light-tightly shut by the third cover element  33 . 
         [0056]    Likewise, mounting rod  38  provided at the carrier  22  is moved along with the carrier  22  relative to wedge-shaped guiding element  39 , whereby the biased mounting rod  38  together with the second aligning element  37  provided on the mounting rod  38  are advanced parallel to the y-direction towards the side face of the cassette  40 . By this structure, the hook-shaped second guiding element  37  comes into contact with the side face of the cassette  40  and advances the cassette  40  against the side end stop  30  provided on the carrier  22 , whereby the cassette  40  is aligned and/or fixed on the carrier  22 . 
         [0057]    The input device  20  shown in  FIGS. 3 to 7  is also designed for receiving cassettes  40  of a third format having a cassette width d 3  being larger than the width d 1  and d 2  of the cassette  40  shown in  FIGS. 4 and 5  or  FIGS. 6 and 7 , respectively. Preferably, the cassette width d 3  of the cassette  40  of the third format corresponds to the width of the slot  26  such that the cassette  40 , when inserted into the input device  20 , covers in essential the whole slot  26 . Additional light shutting can be omitted in this case. Accordingly, not only the first and second cover elements  31  and  32  are tilted up, but also the third cover element  33 . Preferably, the cassette  40  of the third format may be aligned and/or fixed on the carrier  22  by means of a further side end stop  30 ′ (see  FIG. 7 ), which is provided on the carrier  22  opposite to side end stop  30  and can be advanced parallel to the y-direction due to interaction with the wedge-shaped guiding element  39 . Accordingly, the further side end stop  30 ′ acts as an aligning element, like the first and second aligning elements  36  and  37 . 
         [0058]    In summary, by providing cover elements  31  to  33  and/or aligning elements  36 ,  37  and  30 ′ at different positions along the y-direction and advancing these elements by guided mounting elements  34  or  38 , respectively, an alignment and/or fixing of cassettes and/or a light-tight shutting of the input slot  26  can be achieved in a simple and reliable manner in cases when cassettes of three different formats are inserted into the input device  20 . Moreover, the covering and/or aligning mechanisms described above are designed for being purely mechanically driven and therefore particularly robust and cheap in manufacturing. 
         [0059]    Although the functioning of the input device  20  has been elucidated by cassettes  40  of three different cassette widths d 1 , d 2  and d 3 , the approach set forth above can be applied to input devices  20  which are designed for cassettes  40  of more than three different cassette widths.