Patent Publication Number: US-2023148979-A1

Title: X-ray imaging arrangement

Description:
FIELD OF THE INVENTION 
     The invention relates to dental or medical radiography. In particular, structures of an arrangement according to the invention are applicable for use in the context of dental or medical X-ray imaging. 
     BACKGROUND OF THE INVENTION 
     When exposing a living object to ionizing radiation, to generate an image of an anatomy for medical purposes, the imaging must be implemented, in view of the purpose of the imaging, by as low a radiation dose as possible to still get an image of reasonable quality. 
     One parameter to be considered relating to the radiation dose is the volume of the anatomy getting exposed. When not wishing to irradiate inessential parts of an anatomy, one is faced with a problem of proper relative positioning of the desired anatomy and components of the imaging arrangement. 
     To facilitate such positioning, e.g. various positioning lights have been used. Such lights nay be configured to cast e.g. laser lines or a light field on an anatomy. In the context of radiography, a term light field-indicator is sometimes used when referring to an equipment incorporated in an X-ray imaging system which is configured to “predict” the shape and dimensions of the irradiation field during the subsequent exposure. Such systems may include components that are let to remain between the X-ray source and detector also during the imaging exposure while in some others, such components that would remain between the X-ray source and detector are moved away from the X-ray beam path before the X-ray exposure. 
     Computed tomography (CT) is a form of X-ray imaging in which a volume to be imaged is irradiated from different directions and, from the image information on thus acquired, a desired two- or three-dimensional image can be reconstructed. 
     Traditional CT apparatus are large and massive, and they are typically mounted on a floor. A patient is positioned for imaging within an examination opening of the apparatus, typically on a horizontally extending and laterally movable examination platform. 
     Since development of cone beam computed tomography (CBCT) technology in which, for one, slower rotational speeds of the imaging means are used, apparatus of less weight than that of the more traditional CT apparatus have been developed. Among the CBCT apparatus, there also are those not designed to be mounted e.g. on the floor but constructed to be mobile. 
     Some of the CT apparatus designed in recent times are multipurpose apparatus supporting more than one imaging modality, like those configured to enable both 2D and 3D radiography. When having more functionalities, however, complexity of the apparatus tends to increase, e.g. as a consequence of a new kind of freedom of movement having been arranged to one or more components of the apparatus. Also the weight of the apparatus may then increase while some modifications may generate new challenges relating to getting an anatomy positioned for an exposure. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The object of the invention is a medical or dental X-ray imaging arrangement, in one particular embodiment a CBCT apparatus, with novel features relating to mutual positioning of the X-ray source of the arrangement and an anatomy for an imaging exposure. 
     The characteristic features of the invention are defined in claim  1 . More particularly, those features include the arrangement of the present disclosure being configured to enable a light field indicator system to cast a visible light field pattern from essentially the same location as from where an X-ray beam generating system emits an X-ray irradiation beam during an imaging exposure. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention is now described in more detail in reference to some of its preferable embodiments and the attached drawings, of which: 
         FIG.  1    is a schematic general side view showing components, as an example, of an imaging apparatus applicable to comprise features of the present disclosure. 
         FIGS.  2   a - 2   c    show some structural details, as an example, of an embodiment comprising a motorized guiding construction arranged in functional connection with an X-ray source and an X-ray detector. 
         FIG.  3    shows a guiding construction as shown in  FIGS.  2   a - 2   c    as partially covered by a housing of a support construction for the X-ray source  14  and the X-ray detector  15 . 
         FIGS.  4   a - 4   c    show, as an example, a construction to realize a principle of projecting a visible light field pattern towards the X-ray detector from essentially the same location as from where an X-ray beam is configured to be emitted, during an exposure. 
         FIG.  5    shows an embodiment in which the X-ray source and the X-ray detector are located and extend outside the housing of the support construction for the X-ray source and the X-ray detector. 
         FIG.  6    shows a schematic general side view of an embodiment like the one shown in  FIG.  1   , arranged with elements enabling changing orientation. 
         FIG.  7    is a schematic general presentation of an apparatus in horizontal position with certain components thereof driven to locations other than their base positions. 
         FIG.  8   a    shows, as an example, some details of a patient support suitable for use in an apparatus of the present disclosure. 
         FIG.  8   b    shows, as an example, a cross section of a patient support. 
         FIG.  9    is a block diagram showing an example of features of a control system of the apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A more complete understanding of components, processes and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations based on convenience and the ease of demonstrating the present disclosure and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments. 
     Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function. 
     The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. 
     Terms about, generally and substantially when used herein are intended to encompass structural or numerical modifications which do not significantly affect the purpose of the element or number modified by such term. For example, the term substantially may include a range of variance such as 25%, or 10%, or 0% from the stated relationship. 
     As used in the specification and in the claims, the term “comprising” may include the embodiments “consisting of” and “consisting essentially of.” The terms “comprise(s),” “include(s),” “having, ” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named elements/steps and permit the presence of other elements/steps. 
       FIG.  1    shows an apparatus comprising a longitudinally extending frame part  11  extending in a first direction and having a first end and a second end. From this longitudinally extending frame part  11 , or “an elongated frame part  11 ”, extends in a second direction a support construction  12  which supports an X-ray source  14  and an X-ray detector  15  (not as such visible in  FIG.  1   ), the second direction being substantially orthogonal to the first direction. The X-ray source  14  and the X-ray detector  15 , which together can be referred to as an X-ray imaging assembly  14 ,  15 , or be part thereof, may be mounted to the support construction  12  for the X-ray source  14  and the X-ray detector  15  essentially opposite to each other yet in embodiments of the invention, their mutual position may also be arranged to be adjustable. 
     It is to be noted that the apparatus of  FIG.  1   , comprising structures as discussed above, is just an example of one preferable embodiment in the context of which the invention can be implemented. Just as an example, frame and support constructions of also other kind may be applicable, like those comprising “a C-shaped arm” for supporting the X-ray source and the X-ray detector. 
     While medical and dental X-ray imaging apparatus often include a patient support,  FIG.  1    shows one specific kind patient support  18  structure mechanically connected to the elongated frame part  11 . This patient support  18 , applicable for use in various embodiments of the invention, comprises a surface which extends substantially in parallel with the elongated frame part  11 . And while such patient support  18  is optional, in the particular embodiment of  FIG.  1    the patient support  18  is essentially of the same length as the elongated frame part  11 . 
     Examples on how the X-ray source  14  and the X-ray detector  15  may be mounted to the support construction  12  for the X-ray imaging assembly  14 ,  15  are presented when discussing some of the other Figs. of this disclosure further below while  FIG.  1    shows, in general, the support construction  12  for the X-ray imaging assembly  14 ,  15  comprising a housing  121 . The housing  121  may cover a ring-shaped gantry  122 , to which the X-ray imaging assembly  14 ,  15  is mounted. In one embodiment, the housing  121  may extend to cover the X-ray source  14  and the X-ray detector  15  entirely, in another the gantry housing  121  may cover the construction by which the X-ray source  14  and the X-ray detector  15  are mounted to the gantry  122  while not the X-ray source  14  and the X-ray detector  15  themselves. 
     The X-ray source  14  and the X-ray detector  15  may be arranged to be rotatable about a rotation axis  13 . In one embodiment, the ring-shaped gantry  122  to which the X-ray source  14  and the X-ray detector  15  are mounted is rotatable. In the particular construction shown in  FIG.  1   , showing the schematic general side view as discussed above, this rotation axis  13  coincides or can be made to coincide with the central axis of the support construction  12  for the X-ray imaging assembly  14 ,  15 , of the housing  121  and of the ring-shaped gantry  122  as discussed above. 
     Thus, according to one aspect not directly visible in  FIG.  1   , for example, the apparatus comprises a driving mechanism  16  arranged to drive the X-ray source  14  and the X-ray detector  15  about a rotation axis  13 . The rotation axis  13  may be a physical axis, or a virtual rotation axis as in the case of  FIG.  1   . 
     According to one aspect, for example, the rotation axis  13 , or the center of rotation of the X-ray source  14  and the X-ray detector  15  when being driven along a curved path and thus defining a location of the virtual rotation axis  13 , coincides with the central axis of the gantry  122 . 
     According to one aspect, the rotation axis  13  is an instantaneous (optionally virtual) rotation axis and the location of the instantaneous rotation axis in relation to the central axis of the support construction  12  for the X-ray imaging assembly  14 ,  15 , of the housing  121  and/or of the ring-shaped gantry  122  as discussed above can be arranged to be changed. 
     The rotation may be arranged to be performed by rotating the gantry  122  by any conventional mechanism known to those skilled in art. In one embodiment, a driving belt driven by at least one pulley is arranged to extend around a ring-shaped gantry  122 . Such construction can enable implementing rotating the gantry  122  over an angle even exceeding 360 degrees. 
     According to another aspect, another driving mechanism  17  may be arranged to the apparatus to enable moving the support construction  12  for the X-ray imaging assembly  14 ,  15  back and forth in a direction which is substantially parallel with the direction in which the elongated frame part  11  extends. According to one aspect, the driving mechanism  17  may be arranged to move the support construction  12  along or alongside the elongated frame part  11 . 
     According to one aspect, the driving mechanism  17  to drive the support construction  12  in a direction which is substantially parallel with the direction in which the elongated frame part  11  extends can comprise a motor arranged to the support construction  12  for the X-ray imaging assembly  14 ,  15  itself. 
     Regardless of the details of the construction of the driving mechanism  17  to drive the support construction  12  along or alongside the elongated frame part  11 , in one embodiment the construction of the apparatus allows for driving the support construction  12  essentially the whole length between the first and second ends of the elongated frame part  11 . 
     While details of the driving mechanism  17  for moving the support construction  12  for the X-ray imaging assembly  14 ,  15  back and forth in a direction which is substantially parallel with the direction in which the elongated frame part  11  extends may vary, one preferable example of such mechanism is disclosed in a co-pending patent application FI 20190054, which is herein incorporated by reference. 
     Turning to  FIGS.  2   a - 2   c    they show, as an example, some structural details of one possible embodiment which can be used when implementing the invention. In  FIGS.  2   a - 2   c   , a part of the housing  121  of the support construction  12  for the X-ray imaging assembly  14 ,  15  is removed, which makes visible a guiding construction  50  which can be arranged in functional connection with at least the X-ray source  14  of the imaging assembly  14 ,  15 . According to one embodiment, the guiding construction  50  is motorized. 
     While  FIGS.  2   a - 2   c    show two guiding constructions  50 , which are configured to enable laterally moving the X-ray source  14  and the X-ray detector  15  in relation to their support construction  12 , or in relation to the gantry  122 , according to one embodiment only for the X-ray source  14  is arranged a guiding construction  50 . 
     The lateral movement of the X-ray source  14  and/or the X-ray detector  15  in relation to the support construction  12 , or the gantry  122 , can be implemented to take place on a plane which is orthogonal to the rotation axis  13  about which the X-ray source  14  and the X-ray detector  15  are arranged to rotate. 
     According to one aspect, for example, the at least one guiding construction  50  as discussed herein is mounted to a ring-shaped gantry  122  arranged to the support construction  12  supporting the X-ray imaging assembly  14 ,  15 . 
     The range of movement provided by the guiding construction  50  may comprise a base position and a first and a second extreme position, which locate in opposite directions from the base position. 
     While  FIGS.  2   a - 2   c    show an embodiment in which structurally identical guiding constructions  50  are arranged for both the X-ray source  14  and the X-ray detector  15 , and show the guiding construction  50  in different details, for clarity of the Figs. and since not all of the components are even visible in all of them, not each and every component is presented in each of the  FIGS.  2   a - 2   c    with a related reference number. 
     According to one aspect, as an example, the guiding construction  50  comprising a carriage  51  (visible in  FIG.  2   c   ) mounted to at least the X-ray source  14  to enable lateral moving of it. A range of the lateral movement of the carriage  51  may include a base position and a first and a second extreme position locating in opposite directions from the base position. 
     Further, according to one aspect, the at least one guiding construction  50  comprises at least one guiding groove or rail  52  on the side of the support construction  12 , or of the gantry  122 , and a mating construction  52 ′ on the side of the carriage  51  (again, visible in  FIG.  2   c   ). 
     According to one aspect, the at least one guiding construction  50  can comprise a motorized construction  53  in functional connection with the carriage  51 , the motorized construction  53  providing the lateral moving of at least the X-ray source  14  within said range of lateral movement. 
     According to one aspect, the motorized construction  53  can comprise a driving screw  54  which is aligned parallel with the at least one guiding groove or rail  52  and arranged in functional connection with the carriage  51 . According to the embodiment shown in  FIGS.  2   a - 2   c   , the driving screw  54  is arranged to be rotated via a belt  531  driven by a motor  532  yet another construction to rotate the driving screw  54  may be used instead. 
     According to yet another aspect, the guiding construction  50  can include a position sensor arrangement  55  configured to acquire information relating to a position of the X-ray source  14  and/or the X-ray detector  15 , within the range of the lateral movement of at least either of the X-ray source  14  and the X-ray detector  15 . 
     According to one aspect, the position sensor arrangement  55  can be configured to detect a position of the carriage  51  within the range of the lateral movement of the carriage  51 . 
     According to one further aspect, a signal path can be arranged between the at least one guiding construction  50  and the control system of the apparatus. 
     According to one aspect, the signal path can comprise a signal path between the position sensor arrangement  55  and the control system of the apparatus. 
     According to one aspect, the position sensor arrangement  55  is an absolute position sensor arrangement  55 . 
     According to one aspect, the absolute position sensor arrangement  55  can comprise a magnetic component  56  structurally connected to the carriage  51  and movably connected to a rod  57  extending in parallel with the at least one guiding groove or rail  52  and the driving screw  54 . 
     According to one aspect, the first longitudinally extending frame part  11  extends horizontally or is arranged to be moved so as to extend horizontally and the motorized construction  53  of the guiding construction  50  is arranged as self-holding regarding all i) positions of at least either of the X-ray source  14  and the X-ray detector  15  within the range of their lateral movement and ii) rotational positions at which the first driving mechanism  16  is configured to move the X-ray source  14  and the X-ray detector  15  about the virtual or physical rotation axis is  13 . 
     According to one embodiment, the X-ray source  14  and the X-ray detector  15  extend from one same side of the ring-shaped gantry housing  121 , while that particular side of the ring-shaped gantry housing  121  can comprise an otherwise closed surface but on which surface there is an opening  59  for at least either of the X-ray source  14  and the X-ray detector  15 . The opening  59  can be dimensioned to allow for the range of lateral movement of the X-ray source  14  and/or the X-ray detector  15  as guided by the at least one guiding construction  50 . 
       FIGS.  2   c    and  3  show an embodiment including a mounting bracket  58  configured to extend through the opening  59  in the gantry housing  121 . The mounting bracket  58  can be fixed to the carriage  51  at one side and, to the X-ray source  14  and/or the X-ray detector  15  at the other. Differently dimensioned mounting brackets  58  can be used. As another detail, concerning the guiding construction in general, the movement in enables needs not necessarily to be lateral. 
     Referring to  FIGS.  4   a - 4   c   , a configuration is shown which as compared to  FIGS.  2   a - 2   c    further includes a light emitting component. Or, in reference to the disclosure of background to the invention above, shows a light field indicator  141  comprising a visible light emitting construction  141 ′ configured to emit a visible light field pattern. 
     In the example construction of  FIGS.  4   a - 4   c   , the visible light emitting construction  141 ′ is arranged to locate as fixed to a collimator construction  142  of the X-ray source  14  and these three components are arranged movable together as a fixed assembly. Moving of that assembly can be realized, for example, by the kind of guiding construction  50  as discussed above. 
     The light emitting construction  141 ′ may also, as an alternative, be directly attached to the (housing of the) X-ray source  14 , or elsewhere to a frame structure of a collimator construction  142  attached to or being functionally connected to the X-ray source  14 . 
     In a construction such as shown in  FIGS.  4   a - 4   c   , the visible light emitting construction  141 ′ can be configured to be capable of projecting different light field patterns as for their shape and size. Preferably, of essentially the same shapes and/or sizes to which the X-ray beam collimator construction  142  is configured to be able to limit an X-ray beam. 
     Thus, when considering using the construction, the arrangement as shown in  FIGS.  4   a - 4   c    comprising the X-ray source  14 , the collimator construction  142  and the visible light emitting construction  141 ′ can be moved, prior to an imaging exposure, to a position according to  FIG.  4   a    so that the visible light emitting construction  141 ′ will locate essentially at the same location as where the X-ray source locates in  FIG.  4   b   , i.e. at a position from which an X-ray beam will be emitted during an imaging exposure. 
     In other words and more generally, the support construction  12  carrying the X-ray source  14  may be configured to enable positioning the X-ray source  14  and the visible light emitting construction  141 ′ at essentially the same location, so as to when at a given time locating at said essentially same location, they may direct a given field pattern in essentially the same direction towards the X-ray detector  15 . 
     Constructions like the one shown in  FIGS.  4   a - 4   c    thus enable e.g. a procedure to first drive the visible light emitting construction  141 ′ in the position according to  FIG.  4   a   , position an anatomy to be imaged in the imaging area of the arrangement, and then adjust the light field pattern thus cast on the anatomy according to a given imaging mode to be applied, and according to that particular individual anatomy. 
     The procedure may further include the control system of the arrangement comprising information concerning correlation between dimensions of the light field pattern cast towards the X-ray detector  15  and collimation of the X-ray beam, so as to have dimensions of the visible light and X-ray irradiation beams substantially correspond to each other, at the proximity of the X-ray detector  15 . Or, in other words, to have dimensions of the visible light pattern and the X-ray irradiation field pattern substantially correspond to each other at a given distance from the X-ray detector  15 . 
     According to one embodiment, information of the size and shape of the visible light pattern is provided for the X-ray beam collimator control and a component or components of the collimator construction  142  are moved so as to delimit an opening by which the shape and size of the X-ray beam pattern hitting the anatomy will at least substantially correspond to that of the light pattern, when the X-ray source  14  has been moved to a location which substantially corresponds to the location at which the visible light pattern was projected on the anatomy. 
     According to another embodiment, adjusting the light field pattern takes place via controls of the collimator construction  142  such that when the opening the collimator construction  142  limits is adjusted, the shape and size of the light field pattern gets adjusted accordingly, as based on correlation information recorded in the control system of the arrangement. That is, in such embodiment, no separate input means for adjusting the light field pattern is needed as control thereof may take place via controls of the collimator construction  142 . 
     In both embodiments above, the control system of the apparatus may comprise information on which kind of an X-ray beam and light field pattern correspond to each other under given circumstances, like in a context of a given imaging mode to be applied. The imaging mode may be, for example, imaging a certain anatomy from a certain direction which means that, generally speaking, the surface of the anatomy will locate at more or less the same distance from the X-ray detector  15 —and thus also more or less the same distance from the X-ray source  14  and the light emitting component  141  when being positioned at that same location in the support construction  12 . When an imaging mode includes rotation about an anatomy, i.e. scanning the anatomy by an X-ray beam, the light field pattern may be configured to show, instead of or in addition to showing location of the X-ray beam pattern at the initial position of the X-ray beam, the entire or at least part of the entire area where the X-ray beam will travel during the scan. In case of a tomography and especially a CBCT imaging mode, the area of an anatomy indicated by the visible light emitting component  141 ′ may relate to the volume of the anatomy which a given CT imaging mode, in case using a given collimation setting of the X-ray beam, will cover. 
     Using the kind of arrangement shown in  FIGS.  4   a - 4   c   , for example, depending on the context it is not necessarily essential to have the light field pattern and the X-ray beam pattern of precisely the same shape and size. For one, the focus or emission points of the diverging visible light and X-ray beams need not to locate at exactly the same distance from the X-ray detector  15 , and their diverging angles need not to be exactly the same. Regarding differences there may be, they can be taken into account when knowing the differences, and the distance to the location (i.e. surface of an anatomy) at which the patterns should essential match. Such correlation information can be recorded in the control system of the arrangement and thus the pattern dimensions be configured to essentially correspond to each other under given circumstances. 
     While  FIGS.  4   a - 4   c    show an embodiment in which the components X-ray source  14 , X-ray beam collimator construction  142  and visible light emitting construction  141 ′ are arranged to be moved as an integrated assembly, which embodiment includes configuring the control system of the apparatus to provide for the X-ray beam collimator construction  142  the information of the size and shape of the light field pattern being generated, or vice versa, an alternative arrangement is to realize only the X-ray source  14  and the light field indicator  141  as a fixed assembly, which would then be arranged to be moved in relation to the collimator construction  142 . In such embodiment, the collimator construction  142  could be used to limit both the visible light beam and the X-ray beam. 
     As to the accuracy of correspondence of the beam sizes and shapes, or the field pattern sizes and shapes, it is in view of certain aspects more critical to get them closely match each other in the context of using the imaging arrangement to take a single 2D radiograph, as compared to 3D tomographic imaging. 
     In reference to  FIG.  5   , according to one aspect, the support construction  12  comprises a ring-shaped gantry housing  121  which houses i) at least one guiding construction  50  and optionally also ii) driving mechanism  16  arranged to move the X-ray imaging assembly  14 ,  15  about the virtual or physical rotation axis  13 , whereas the X-ray source  14  and the image detector  15  are arranged to locate or extend outside the ring-shaped gantry housing  121 . 
     According to one embodiment, the X-ray source  14  and/or the X-ray detector  15  can include a housing for the X-ray source  14  and/or the X-ray detector  15  which is so designed and dimensioned that in all positions within the range of the lateral movement of at least either of the X-ray source  14  and the X-ray detector  15 , the housing covers the opening  59  through which the mounting bracket  58  extends. 
     According to one aspect, in case of there being more than one pulsing construction  50  they can comprise the same number of components having the same functions so as to form similarly functioning assemblies. As an example, the guiding constructions may be identical while optionally the mounting brackets  58  may be different, as adapted specifically for the X-ray source  14  and the image detector  15 . 
     According to one aspect when the housing  121  of the support construction  12  does not encase the X-ray source  14  and the X-ray detector  15 , but functions primarily or solely as a housing for e.g. the ring-shaped gantry  122 , to which the X-ray source  14  and the X-ray detector  15  are mounted, and for the structures arranged to the apparatus to drive the X-ray source  14  and the X-ray detector  15  about the rotation axis  13 , the support construction  12  can be realized to be lighter and to provide a possibility for better access for patients and personnel to the imaging volume between the X-ray source  14  and the X-ray detector  15 . Such embodiment can also make it easier for the personnel to have a clear line of sight at the imaging volume inside the housing  121 , whereto the patient is to be positioned for an exposure. 
     Turning to  FIG.  6    which shows, as an example and as a schematic general side view, certain components of an embodiment in which, in addition to what can be referred to as a first elongated frame part  11  discussed above, there is a second elongated frame part  21  mechanically connected to the first elongated frame part  11 , of essentially the same length as the first elongated frame part  11 . 
     According to one aspect and still referring to  FIG.  6   , at the proximity of the first end of the elongated frame parts  11 ,  12  is arranged an articulated connection construction  22  to mechanically connect the first and second elongated frame parts  11 ,  21 , to allow for tilting of the first elongated frame part  11  about at least one tilt axis in relation to the second elongated frame part  21 . The at least one tilt axis may be an axis which is orthogonal to the direction in which the first and second elongated frame parts  11 ,  21  extend as well as to direction in which the support construction  12  for the X-ray imaging assembly  14 ,  15  extends—perpendicularly from the first longitudinally extending frame part  11 . 
     In the embodiments shown in  FIG.  6   , the at least one tilt axis is horizontal. 
     According to another aspect, on the side of the second elongated frame part  21 , a mounting structure  23  not directly visible in  FIG.  6    is arranged in connection with the articulated connection construction  22 . The mounting structure  23  is arranged movable along or alongside the second elongated frame part  21 . 
     According to another aspect, for example, in the proximity of the second end of the second elongated frame part  21  is arranged a locking mechanism  24  configured to enable connecting and disconnecting the first and second elongated frame parts  11 ,  21 . Particularly, the locking mechanism  24  may be arranged in the proximity of the second end of the first and second elongated frame parts  11 ,  21  and as configured to enable connecting together and disconnecting the first and second elongated frame parts  11 ,  21  at the proximity of the second ends of the first and second elongated frame parts  11 ,  21 . 
     When the second elongated frame part  21  is mounted stable and the locking mechanism  24  is not connecting the first and second elongated frame parts  11 ,  21 , the second end of the first elongated frame part  11  is free to move laterally while the articulated connection  22  between the frame parts  11 ,  21  allows for turning of the first elongated frame part  11  about the horizontal tilt axis, at the proximity of the first end of the first elongated frame part  11 . In case of a vertical starting position, such movably arranged mounting structure as discussed above allows for descending and ascending of the first end of the first elongated frame part  11 . 
     While the construction allowing for tilting of the first elongated frame part  11  and descending and ascending of the first end of the first elongated frame part  11 , as well as that of the locking mechanism  24  discussed above may vary, examples of such are disclosed in more detail in a co-pending patent application FI 20190054, which is incorporated herein by reference. 
       FIG.  6    shows the apparatus at a stage where the first end of the first elongated frame part  11  has moved downwards and the second end of the first elongated frame part  11  has moved horizontally on a surface. The apparatus of  FIG.  6    may be configured to allow for descending of the first end of the first elongated frame part  11  all the way to the proximity of the second end of the second elongated frame part  21 . 
     According to yet another aspect, not directly visible in  FIG.  6   , in functional connection with the second elongated frame part  21  is arranged a driving mechanism  27  to drive the mounting structure  23  along or alongside the second elongated frame part  21 . When being in mechanical connection with the first elongated frame part  11 , at the proximity of the first end of it, the driving mechanism  27  can move the first end of the first elongated frame part  11  in a direction in which the second elongated frame part  21  extends. 
     The driving mechanism  27  to drive the mounting structure  23  may be a construction similar with the driving mechanism  17  driving the support construction  12  of the X-ray imaging assembly  14 ,  15  along or alongside the first elongated frame part  11 . 
     According to one aspect, the driving mechanism  27  to drive the mounting structure  23  comprises a chain drive. 
       FIG.  7    is a schematic general presentation of an apparatus, as an example, extending in horizontal direction. While not shown in  FIG.  7   , the apparatus may comprise constructions as discussed in connection with  FIG.  6    which allows for changing the direction in which the elongated frame part  11  extends. The support construction  12  for the X-ray imaging assembly  14 ,  15  in  FIG.  7    is not similar with that of  FIG.  6   , while  FIG.  7    shows certain components of the apparatus as driven to locations other than their base position. 
     That is, regarding e.g. the aspect of access to the volume between the X-ray source  14  and the X-ray detector  15 ,  FIG.  7    illustrates how certain components of the apparatus may be moved to various locations within ranges of movements arranged for them. According to that embodiment, while the embodiments discussed above to laterally move at least either of the X-ray source  14  and the X-ray detector  15  can be used to ease access of a patient inside the support construction  12  for the X-ray imaging assembly  14 ,  15 , another similarly construed construction or another similarly functioning construction may be arranged in the apparatus to also laterally move the support construction  12  for the X-ray imaging assembly  14 ,  15  itself, in relation to the elongated frame part  11 . By incorporating such linear movement mechanism  50 ′ to the apparatus, e.g. even more room may be provided for the patient to enter the imaging area and then get properly positioned for an exposure. 
     Thus, according to one aspect, the apparatus further comprises a linear movement mechanism  50 ′ arranged to enable moving the support construction  12  for the X-ray imaging assembly in relation to the longitudinally extending frame part  11  in a direction which is at right angles to the direction in which the longitudinally extending frame part  11  extends. A range of the linear movement of the support construction  12  may comprise a base position in relation to the first longitudinally extending frame part  11  and a first and a second extreme position. 
     When the support construction  12  for the X-ray imaging assembly  14 ,  15  extends in a direction at right angles to the longitudinally extending frame part  11 , the direction in which the linear movement mechanism  50 ′ moves the support construction  12  for the X-ray imaging assembly  14 ,  15  in relation to the longitudinally extending frame part  11  is also at right angles to that direction. 
     Concerning the base position provided by the linear movement mechanism  50 ′ for the support construction  12  for the X-ray imaging assembly  14 ,  15 , in embodiments either of the first and second extreme positions may be the base position. The same applies concerning the guiding construction  50  for at least the X-ray source. 
     According to yet another aspect and as shown in  FIG.  8   a   , the connection construction  19 ,  20  which mechanically connects the patient support  18  to the elongated frame part  11  may comprise a patient support adjustment mechanism  19 ′,  20 ′ configured to enable displacing the patient support  18  closer and further away from the (first) elongated frame part  11 . 
     According to another aspect, a patient support driving mechanism  19 ″,  20 ″ is arranged in functional connection with the patient support adjustment mechanism.  19 ′,  20 ′. 
     According to another aspect, the patient support adjustment mechanism  19 ′,  20 ′ may comprise a first adjustment mechanism  19 ′ arranged together with its driving mechanism  19 ″ comprised in the patient support driving mechanism  19 ″,  20 ″ substantially at the first end of the elongated frame part  11 , and a second adjustment mechanism  20 ′ arranged together with its driving mechanism  20 ″ comprised in the patient support driving mechanism  19 ″,  20 ″ substantially at the second end of the elongated frame part  11 . 
     According to one aspect, for example, the patient support adjustment mechanisms  19 ′,  20 ′ is arranged in functional connection with the control system of the apparatus and the control system is configured to control the patient support driving mechanism  19 ″,  20 ″ of the patient support adjustment mechanism  19 ′,  20 ′. 
     According to one aspect, for example, the control system is configured to control the connection construction  19 ,  20  comprising the first adjustment mechanism  19 ′ with its driving mechanism  19 ″, arranged substantially at the first end of the (first) elongated frame part  11 , and the second adjustment mechanism  20 ′ with its driving mechanism  20 ″, arranged substantially at the second end of the (first) elongated frame part  11 , to keep at the first and second ends of the elongated frame part  11  an identical distance between the (first) elongated frame part  11  and the patient support  18  when adjusting the distance between the two. 
     According to another aspect, the distance between the ends of the (first) elongated frame part  11  and the patient support  18  can be adjusted to be different. 
     According to one aspect, as shown in  FIG.  8   b   , considering the above-discussed first direction of the patient support  18 , its cross section as for its prevailing part is curved so as to better support a patient against the concave surface of the patient support  18 . 
     According to one other aspect, as shown in  FIG.  8   b   , at the edges  181  of that cross section of the patient support  18 , the shape of the cross section turns into being curved in the opposite direction. 
     According to one other aspect and as further shown in  FIG.  8   b   , near the edges of the above-discussed cross section of the patient support  18  and on the side opposite to the for its prevailing part concave surface, is arranged a holding structure  182 . The holding structure  182  may be e.g. an elongated handle or an attachment structure to receive a strap designed to extent on or over the concave side of the patient support  18 , to be used to provide further support to the patient and thus to help keeping still during an imaging exposure. 
     According to one aspect, and as already generally mentioned above, the various degrees of freedoms of movement of the components of apparatus, including those that may be arranged for the patient support  18 , may be taken advantage of when positioning a patient, or to be more exact, an anatomy for an exposure. As an example, considering a situation of a patient&#39;s shoulder to be examined while lying on a patient support  18  like the one discussed above, one can first drive the patient support  18  to be located at a height position which is easiest for the patient to get on the patient support  18 . Then, when the patient is lying on the patient support  18 , at least one of i) the height position of the patient support  18 , ii) horizontal position of the support construction  12  for the X-ray imaging assembly  14 ,  15 , and iii) position of at least either of the X-ray source  14  and the X-ray detector  15  within the range of the lateral movement provided therefor can be adjusted so that the desired anatomy will locate at the field of view of the apparatus. This, obviously, within the limits of the degrees of freedoms of movement of the components of apparatus arranged therefor. 
     Structures according to embodiments enable arranging to the apparatus various patient entry and positioning operations. They can also be taken advantage of to perform e.g. other than traditional kind CT imaging and, in addition to CT imaging, also imaging modes with no rotation but mere linear movement of the X-ray imaging assembly may be deployed. Specifically, embodiments may be applied in the context of positioning an anatomy for an individual 2D imaging exposure. 
     The operation modes such as those discussed above may include, as a pre-exposure operation, driving the guiding construction  50  for the X-ray source  14  to which is connected the visible light emitting construction  141 ′ such that the visible light emitting construction  141 ′ will be moved to locate at essentially the base position of the X-ray source  14 , and adjusting the field pattern generated by the visible light emitting construction  141 ′ to be of a default shape and size. The default shape and size may be set according to an imaging mode, which may be arranged to be selected from the user interface of the apparatus. 
     According to an embodiment, a selected imaging mode may include driving the X-ray source  14  and the X-ray detector  15  a distance from their base positions. The apparatus may be configured to allow for, after such pre-exposure operation, to adjust the light field pattern, and thus the X-ray beam size and/or shape to be used during the imaging exposure, according characteristics of a given anatomy positioned for imaging. 
     In an embodiment, the arrangement is equipped with a component or components adapted to determine the location and/or the shape of the anatomy positioned for imaging, and the control system to then adjust the X-ray beam collimation and/or the projected visible light pattern on the anatomy using that knowledge. Technologies to determine distance to and shape of a surface in a coordinate system exist, as well as to transfer information from one coordinate system to another—in this case, when knowing the geometry of the (relevant components of the) imaging arrangement, and correlation of that to the coordinate system in which the surface location and shape is determined. In embodiments, instead of determining the shape of the surface of the anatomy, e.g. just a shortest distance from the said same location to the surface of the anatomy may be determined. 
     Pre-exposure operations relating to mutual positioning of the anatomy and the imaging assembly and adjusting the X-ray beam size and shape according to a given imaging mode, and even according to the anatomy to be imaged, may be applied in the context of various imaging modes arranged to the imaging apparatus. Such an operation may include, in general, the control system of the apparatus comprising geometric information regarding mutual positions of the X-ray source, the light emitting construction  141 ′, the X-ray detector and/or the patient support such that for a given light field pattern and the location from where it is cast, the control system comprises corresponding collimation information for limiting the X-ray beam when the X-ray beam is emitted at a given location of the X-ray source, in a context of a given imaging mode. 
     An operation mode may include, as an example, a pre-exposure operation of—prior to optionally driving the X-ray source  14  and the X-ray detector  15  from their base positions, driving the guiding construction  50  for the X-ray source  14  to which is connected the visible light emitting construction  141 ′ such that the visible light emitting construction  141 ′ will be moved to locate at essentially the base position of the X-ray source  14 , and adjusting the field light pattern generated by the visible light emitting construction  141 ′ to be of a default shape and size. The default shape and size may be pre-set according to an imaging mode selected from the user interface of the apparatus. 
     According to an embodiment, as an example, the selected imaging mode includes driving the X-ray source  14  and the X-ray detector  15  a distance from their base positions. The apparatus may be configured to allow for, after such pre-exposure operation, adjusting the light field pattern, and thus the X-ray beam size and shape to be used during the imaging exposure, according characteristics of a given individual anatomy positioned for imaging. 
     Concerning a given patient entry operation or patient entry mode, according to one aspect, it includes the visible light emitting construction  141 ′ being positioned at the same place as where the X-ray source will be positioned during, or at the beginning of a subsequent imaging exposure. 
     According to one aspect, then, the light field indicator  141  may be configured to be able to project a light beam of the same shape as is the shape of an X-ray beam the X-ray source  14  is configured to emit, or can be adjusted to emit. Such light field indicator  141  may be mounted to the same guiding construction  50  as the X-ray source  14 , e.g. as a component separate from the X-ray source  14 , so as to be movably mounted in relation to the support construction  12 . The range of movement of the guiding construction  50  to which the X-ray source  12  and the light emitting component may be mounted is then preferably so configured that the X-ray source  14  and the light emitting construction  141 ′ can be positioned at the same location within the range of movement the guiding construction  50  provides. Such configuration provides a novel arrangement by which one is able to cast a positioning light pattern on the object to be imaged from the same location at which the actual X-ray imaging exposure is to take place, or begin. 
       FIG.  9    shows as a block diagram an example of components of a control system applicable for use in the arrangement. The control system according to  FIG.  9    is configured to enable controlling, first of all, operation of the X-ray source  14  and the X-ray detector  15  (imaging means, or assembly) during an exposure, according to an imaging mode. Components controlling operation of the X-ray source  14  and the X-ray detector  15  can include components physically arranged to the X-ray source  14  and/or the X-ray detector  15  and/or elsewhere in the apparatus. 
     The control system may further be configured to control various driving means of the apparatus, such as those driving the one or more than one guiding construction  50  as well those moving the support construction  20  for the X-ray imaging assembly  14 ,  15 . A signal path can also be arranged for controlling components discussed above relating to adjusting the shape and size of the field patterns, and positioning of these components in relation to the support construction  12 . 
     The control system of  FIG.  9    further shows optional features of rotating the X-ray imaging assembly  14 ,  15  as well as the patient entry mode feature, which may include controlling at least one of the above-discussed driving means. 
     Further shown in  FIG.  9    is a signal path to the mounting structure  23  as discussed further above and, in case of the apparatus comprising a motorized locking mechanism  24  to connect and disconnect the first and second elongated frame parts  11 ,  21  as discussed above, the control system may also control driving of the locking mechanism  24 . 
     Overall, the control system may be arranged to control the above-discussed operations or a portion thereof. The structures and functionalities discussed above offer various possibilities to ease positioning and performing imaging of a desired volume of a patient. 
     Control signals for various operations may be triggered as a response to a detected operation or input from the user interface of the apparatus. The memory of the control system may include various correlation information of pattern shapes and dimensions as discussed above, and related control protocols as discussed above, as well as protocols relating to one or more entry and/or imaging mode. 
     While various embodiments are discussed above, an arrangement of this disclosure can be described as a dental or medical X-ray imaging arrangement which comprises an X-ray detector, an X-ray source configured to generate X-ray irradiation and comprising a collimator construction functionally connected to the X-ray source, the collimator construction being configured to limit the X-ray irradiation generated by the X-ray source into a beam to be aimed in the direction of the X-ray detector and defining an X-ray irradiation field pattern, a light field indicator comprising a visible light emitting construction and being configured to project a visible light field pattern to be aimed in the direction of the X-ray detector, a support construction to which the X-ray source and the visible light emitting construction are mounted, and a control system comprising control information relating to an imaging mode. Further, the support construction may be configured to enable positioning the X-ray source and the visible light emitting construction at essentially the same location in relation to the support construction  12 , so as to when at a given time locating at said essentially same location, to direct a given field pattern in essentially the same direction towards the X-ray detector. 
     To add to, or summarize some of the features discussed above, embodiments may include that the X-ray source  14 , the collimator construction  142  and the visible light emitting construction  141 ′ are arranged to be movable as a fixed assembly. On the other hand, the X-ray source  14  and the visible light emitting construction  141 ′ may be arranged to be movable as a fixed unit in relation to the collimator construction  142 . 
     The light field indicator  141  may be configured to generate the visible light field pattern such that the pattern is a substantially evenly illuminated area or comprises a pattern of light fields which as a combination indicates an area. Further, the light field indicator  141  may be configured to enable projecting visible light field patterns of different sizes and/or different shapes, and the collimator construction  142  to enable limiting X-ray irradiation field patterns of different sizes and/or of different shapes. 
     The control system may comprise correlation information relating to dimensions of the visible light field pattern and the X-ray irradiation field pattern, at a given distance from the X-ray detector  15 , and the light field indicator  141  and the collimator construction  142  are configured to enable adjusting dimensions and/or shape of their respective field patterns according to the correlation information such that the field patterns cover essentially the same area at said given distance from the X-ray detector  15 , and wherein the correlation information optionally includes correlation information relating to a given imaging mode. A given imaging mode may be a CBCT imaging mode and the control system be configured to enable indicating by the visible light field pattern an area at a given distance from the X-ray detector  15  relating to a volume which, regarding a given CBCT imaging mode and in case using a given collimation setting of the X-ray beam, will cover. 
     The arrangement may further comprise a component or components configured to determine location and/or shape of an anatomy positioned for imaging, and the control system then configured to be able adjust the X-ray beam collimation and/or the projected visible light pattern on the anatomy using that knowledge, the location and/or shape then defining the given distance from the X-ray detector  15 . 
     The control system may also be configured to receive information from the light field indicator  141  on the characteristics of the visible light pattern it projects and to convert said received information to information on how to control operation of the collimator construction  142  so as to adjust the X-ray irradiation field pattern to at least substantially correspond to the size and shape of the area the projected visible light pattern indicates. 
     The control system may further be configured to receive information from the collimator construction  142  on the characteristics of the X-ray irradiation field pattern it limits and to convert the received information to information on how to control operation of the light field indicator  141  so as to adjust the visible light field pattern to at least substantially correspond to the size and shape of the X-ray irradiation field pattern. 
     The arrangement may comprise a first guiding construction  50  mounted to the support construction  12 , wherein the X-ray source  14  and the visible light emitting construction  141 ′ are mounted together as a fixed unit and the first guiding construction  50  is configured to enable moving that fixed unit, a range of that movement comprising a base position and a first and a second extreme position. The first guiding construction  50  may comprise a carriage  51  mounted to said fixed unit comprising the X-ray source  14  and the visible light emitting construction  141 ′, a range of the movement of the carriage  51  comprising a base position and a first and a second extreme position. 
     The first guiding construction  50  may comprise a at least one guiding groove or rail  52  on a side of the support construction  12  and a mating construction  52 ′ on a side of the carriage  51 . On the other hand, the first guiding construction  50  may comprise a motorized construction  53  in functional connection with the carriage  51 , the motorized construction  53  providing the moving of the fixed unit comprising the X-ray source  14  and the visible light emitting construction  141 ′ within that range comprising the first and second extreme positions. The first guiding construction  50  may also include a position sensor arrangement  55  configured to acquire information relating to a position of the fixed unit comprising the X-ray source  14  and the visible light emitting construction  141 ′ within that range of movement, the position sensor arrangement  55  being configured to detect a position of the carriage  51  within the range of movement of the carriage  51 . The first guiding construction  50  may be configured to enable laterally moving said fixed unit and the motorized construction  53  may comprise a driving screw  54 , the driving screw  54  being aligned parallel with the at least one guiding groove or rail  52  and arranged in functional connection with the carriage  51 . 
     The position sensor arrangement  55  may comprise a magnetic component  56  structurally connected to the carriage  51  and movably connected to a rod  57  extending in parallel with said at least one guiding groove or rail  52  and said driving screw  54  of the guiding construction  50 . 
     A mounting bracket  58  may be fixed to the carriage  51  and, on the other hand, to the fixed unit comprising the X-ray source  14  and the visible light emitting construction  141 ′, to mechanically connect the fixed unit to the guiding construction  50 . 
     A signal path can be provided between the first guiding construction  50  and the control system. The signal path may comprise a signal path between the position sensor arrangement  55  and the control system. 
     A signal path may also be provided between the collimator construction  142  and the control system, and between the light field indicator  141  and the control system, to enable controlling the collimator construction  142  and the light field indicator  141  according to the correlation information. 
     Further, the X-ray detector  15  may be mounted to the support construction  12  to which the X-ray source  14  and the visible light emitting construction  141 ′ are mounted. The arrangement may comprise a further X-ray detector mounted elsewhere than to the support construction  12  to which the X-ray source  14  and the visible light emitting construction  141 ′ are mounted, and that mounting of the X-ray source  14  and the visible light emitting construction  141 ′ to the support construction  12  may be realized as allowing for directing their respective field patterns in essentially the same direction towards both of the X-ray detectors. 
     The support construction  12  to which the X-ray source  14  and the visible light emitting construction  141 ′ are mounted may comprise a ring-shaped structure. The ring-shaped structure may comprise a ring-shaped gantry  122  and a housing  121  which houses at least said ring-shaped gantry  122  and the first guiding construction  50 . The housing  121  may comprise a surface with at least one opening  59  for mounting by the mounting bracket  58  through the at least one opening  59  at least the X-ray source  14 , wherein the at least one opening  59  is dimensioned so as to allow for the range of movement of the X-ray source  14  as guided by said guiding construction  50 . 
     An arrangement as discussed above may then comprise a first frame part  11  extending in a first direction and comprising a first end and a second end, and the support construction  12  may extend from the first frame part  11  in a second direction essentially at right angles to the first direction. The positioning of the X-ray source  14  and the visible light emitting construction  141 ′ at essentially the same location may include arranging the X-ray source  14  and the visible light emitting construction  141 ′ movable in a direction at right angles to both those first and second direction.