Abstract:
An extra-oral imaging apparatus is intended to obtain a cephalometric image of a portion of a head of a patient. Exemplary apparatus embodiments of cephalometric functionality of such extra-oral imaging apparatus can include a cephalometric support mounted to a base of the imaging system that is configured to position a cephalometric sensor about a cephalometric imaging area so that x-rays impinge the cephalometric sensor after radiating the cephalometric imaging area. A cephalometric collimator can be mounted to a patient positioning unit to provide secondary collimation of the x-ray beam for the cephalometric sensor. Exemplary apparatus and/or method embodiments of the application relates to providing a measurable indication of alignment between a cephalometric collimator and cephalometric sensor or the extra-oral imaging apparatus, which can provide a repeatable and/or accurate alignment between a cephalometric collimator and cephalometric sensor.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to the field of dental x-ray imaging, and more particularly, to a cephalometric x-ray imaging functionality for dental applications. Further, the invention relates to a cephalometric dental imaging apparatus and/or methods. 
       BACKGROUND 
       [0002]    Cephalometric imaging (or transillumination imaging) is regularly used by dental practitioners, for example, in orthodontic applications. For cephalometric imaging techniques, an image of the x-ray radiated skull of the patient is projected on an x-ray sensitive surface located away from the x-ray source using a cephalometric arm. In most of the cases, the sensor is positioned at the extremity of a long cephalometric arm and is positioned at a distance about  1 . 8  meters away from the x-ray source. The necessity to have the sensor positioned far away from the x-ray source originates from the necessity to have an approximately equal magnitude factor for every part of the patient&#39;s skull. The imaging process may consist in one single shot of the patient&#39;s skull with the x-ray beam impinging a full (e.g., square) sensor after radiating the patient. One advantage of single shot image acquisition is that it can be short in time, less than one second. The single shot image can reduce effects from any motion of the patient. One drawback of single shot image acquisition is that the large sensor is very expensive. As an alternative to decrease the size of the sensor, a linear elongated sensor can be used in association with a linearly elongated (e.g., vertical) slit-shaped collimator that aims at shaping the x-ray beam before the x-ray beam radiates the patient. The patient is positioned between the elongated collimator and the elongated sensor. A linear scan can be performed by horizontally translating a vertically elongated sensor and a vertically elongated collimator and changing the direction of the x-ray beam accordingly through the use of a primary collimator positioned in front of the X-ray source. The images collected during the scan are merged together to form a projection of the patient&#39;s skull. In the cephalometric or skull imaging technique, the patient can be positioned facing the x-ray beam or in a profile position. 
         [0003]    Most current manufacturers use a small elongated sensor that can slide to carry out a scan of the whole patient&#39;s head. In scanning image acquisition, both a primary collimator, which may be a variable collimator, in front of an x-ray source and a second collimator (e.g., cephalometric collimator), which may be a variable collimator, positioned before the patient&#39;s head are slit-shaped. The secondary collimator and the x-ray sensor simultaneously slide during the scan in such a way that the center of the apertures of the variable primary collimator, the center of the aperture of the secondary collimator and the center of the x-ray sensor are all three aligned at any time of the scan. Such an alignment is known from the related art. Again, a plurality of images are collected by the elongated x-ray sensor, stored and stitched together to create a whole skull image. 
         [0004]    The direction of the secondary collimator&#39;s slit and the direction of the elongated active surface area of the sensor may not be perfectly parallel (e.g., misaligned or the secondary collimator or collimator aperture/slit can be tilted relative to the active area of the x-ray sensor). Misalignment of the secondary collimator and the x-ray sensor can lead to truncated images and/or some x-rays that radiate the patient are then not collected by the x-ray sensor, which can lead to unnecessary exposure of the patient. Conventional apparatus and/or methods of alignment are long and cumbersome and necessitate iterative attempts to align both directions and include successive corrective positioning of the collimator&#39;s tilt followed by imaging tests. Such an alignment is complicated by the fact that the cephalometric imaging unit is located at a large distance away from the source of x-ray beam. 
         [0005]    It can be appreciated that there is still a need for installation apparatus and/or methods that can provide a cheaper, rapid, and/or accurate assessment of a correctness of an installation/adjustment/alignment of a cephalometric module (e.g., dental cephalometric imaging device) or alignment (e.g., vertical) of a slit of the secondary collimator and the elongated active area of the x-ray sensor of a cephalometric module. 
       SUMMARY 
       [0006]    An aspect of this application is to advance the art of medical digital radiography, particularly for dental cephalometric applications. 
         [0007]    Another aspect of this application is to address, in whole or in part, at least the foregoing and other deficiencies in the related art. 
         [0008]    It is another aspect of this application to provide, in whole or in part, at least the advantages described herein. 
         [0009]    An advantage offered by apparatus and/or method embodiments of the application relates to providing a measurable indication of alignment between a cephalometric collimator and cephalometric imaging sensor. 
         [0010]    Another advantage offered by apparatus and/or method embodiments of the application relates to providing a repeatable and/or accurate indication of alignment between a cephalometric collimator and cephalometric imaging sensor. 
         [0011]    These aspects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. The invention is defined by the appended claims. 
         [0012]    According to one aspect of the disclosure, there is provided a method for aligning a cephalometric imaging unit to an extra-oral imaging system that can include 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. 
           [0014]    The elements of the drawings are not necessarily to scale relative to each other. Some exaggeration may be necessary in order to emphasize basic structural relationships or principles of operation. Some conventional components that would be needed for implementation of the described embodiments, such as support components used for providing power, for packaging, and for mounting and protecting x-ray system components, for example, are not shown in the drawings in order to simplify description. 
           [0015]      FIG. 1  is a diagram that shows an extra oral imaging device including a cephalometric imaging module. 
           [0016]      FIG. 2  is a diagram that shows a top view of an ensemble including an x-ray source with a first collimator, a second collimator and a cephalometric sensor. 
           [0017]      FIG. 3  is a diagram that shows a longitudinal view representing, an x-ray source, a secondary collimator, a cephalometric sensor and a projection of the twice collimated beam from the x-ray source on the geometric plane of the cephalometric sensor. 
           [0018]      FIG. 4  is a diagram that shows represents the area of the active surface of the sensor that is impinged by the x-ray beam for an initial position of the secondary collimator relative to the x-ray sensor. 
           [0019]      FIG. 5  is a diagram that shows an exploded view of the ensemble comprising an exemplary carriage and an exemplary platen with fixing means according to embodiments of the application. 
           [0020]      FIGS. 6 and 7  are diagrams that show two different representative positions of a platen relative to a carriage according to embodiments of the application. 
           [0021]      FIG. 8  is a diagram that shows a cross section of an exemplary ensemble embodiment including a carriage and a platen that are secured to a belt and positioned on a guiding rail of a cephalometric platform, where the carriage and platen are holding a secondary collimator according to the application. 
           [0022]      FIG. 9  is a diagram that shows an isometric view of the exemplary ensemble embodiment of  FIG. 8  secured to the guiding rail according to the application. 
           [0023]      FIG. 10  is a diagram that shows an exemplary detachable tilting device embodiment attached to a cephalometric platform according to the application. 
           [0024]      FIG. 11  is a diagram that shows a front view of an exemplary connection of a secondary collimator on the carriage and the platen according to embodiments of the application. 
           [0025]      FIG. 12  is a diagram that shows an isometric view of exemplary detachable tilting device embodiment of  FIG. 10 . 
           [0026]      FIG. 13  is a diagram that shows a rear view of a secondary collimator and an exemplary detachable tilting device embodiment at a start position of the collimator sliding movement towards a rotation point or device according to the application. 
           [0027]      FIG. 14  is a diagram that shows a rear view of the secondary collimator and an exemplary detachable tilting device embodiment at the end position of the collimator in his sliding movement with a contact between the rotation device and the collimator according to the application. 
           [0028]      FIGS. 15 a , 15 b  and 15 c    are diagrams that show exemplary projection images obtained by the cephalometric sensor when the x-ray beam is shaped by the secondary collimator when the secondary collimator is tilted on one side relative to the cephalometric sensor, when the secondary collimator is in good alignment with the cephalometric sensor and when the secondary collimator is tilted on the other side relative to the cephalometric sensor according to embodiments of the application. 
           [0029]      FIG. 16  is a diagram that shows an exemplary image obtained when the x-ray beam is aligned and centered relative to the cephalometric sensor according to embodiments of the application. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0030]    The following is a description of exemplary embodiments, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures. 
         [0031]    Where they are used in the context of the present disclosure, the terms “first”, “second”, and so on, do not necessarily denote any ordinal, sequential, or priority relation, but are simply used to more clearly distinguish one step, element, or set of elements from another, unless specified otherwise. 
         [0032]    As used herein, the term “energizable” relates to a device or set of components that perform an indicated function upon receiving power and, optionally, upon receiving an enabling signal. The term “actuable” has its conventional meaning, relating to a device or component that is capable of effecting an action in response to a stimulus, such as in response to an electrical signal, for example. 
         [0033]    Apparatus and/or method embodiments according to the application aim at facilitating an installation process by giving the technician a highly precise rapid assessment of the correctness of the adjustment of the cephalometric collimator. 
         [0034]      FIG. 1  is a diagram that shows an extra oral imaging device including a cephalometric imaging module. As shown in  FIG. 1 , an extra oral x-ray imaging device  1  for use with embodiments of the application can include a gantry  2  supporting an x-ray source  3  comprising a focal spot  40 , embodied with a variable primary collimator  42  and a CT and/or panoramic sensor  4  facing the x-ray source  3  with a patient&#39;s positioner  5  in-between. The x-ray source  3  and sensor  4  can be near opposite ends of gantry  2 . A cephalometric imaging unit  6  is mounted on (e.g., positioned at the end of) a cephalometric arm  7 . Due to the long distance between the x-ray source  3  and a cephalometric sensor  20  (typically  1 . 8 m), a primary collimator  42  in front of the x-ray source  3  cannot collimate the x-ray beam  43  precisely enough. A secondary collimator  10  with an aperture  11  (e.g., elongated or slit-shaped) is held on a cephalometric platform  100  and can slide along a first rail  91 . Then, a beam  43  originating from the x-ray source  3  and shaped by the primary collimator  42  can be shaped a second time into an x-ray beam  44  by the secondary collimator  10 . A cephalometric sensor  20  with an elongated active area  21  is also held on the cephalometric platform  100  and can slide along a second rail  92 . A patient holder  30  to fixedly hold the patient can be located between the secondary collimator  10  and the sensor  20 . 
         [0035]      FIG. 2  is a diagram that shows a top view of an ensemble including an x-ray source with a first collimator, a second collimator and a cephalometric sensor. As shown in  FIGS. 1-2 , the sliding movement of the collimator  10  and the sensor  20  can be controlled in such a way that a center of the aperture  41  of the primary collimator  42  of the x-ray source  3 , the center of the aperture  11  of the secondary collimator  10  and the center of the active area  21  of the sensor  20  are aligned at any time of the scan of the patient head  31  extra oral x-ray imaging device  1 . 
         [0036]      FIG. 3  is a diagram that shows a longitudinal view representing an x-ray source, a secondary collimator, a cephalometric sensor and a projection of a twice collimated beam from the x-ray source on the geometric plane of the cephalometric sensor. As shown in  FIG. 3 , the direction of the slit  11  of the secondary collimator  10  is not parallel to the direction of the elongated active area  21  of the sensor  20 . The geometric plane of the cephalometric sensor is shown from the direction of the x-ray beam  43  in  FIG. 3 . The beam  43  originating from the focal spot  40  of the source  3  is shaped into the beam  44  by the slit  11  of the collimator  10 . The beam  44  then projects toward the geometrical plane of the sensor as an area  45  that may only partially coincide with the active area  21  of the sensor.  FIG. 4  is a diagram that is a representation of the image obtained from the misalignment of  FIG. 3 . It is noticed especially that the edge  46  of the surface  45  of the sensor is not parallel to the edge  21   a  of the active area of the sensor.  FIG. 4  can represent the area of the active surface  21  of the sensor  20  that is impinged by the x-ray beam  44  for an initial position of the secondary collimator  10  relative to the x-ray source/sensor. Then, the tilt of the direction of the slit  11  of the collimator  10  relative to the direction of the active area  21  of the sensor  20  has to be corrected by method and/or apparatus embodiments according to the invention. 
         [0037]    Further, it is also observed in Fig. 3  (and  FIG. 4 ) that a center of the slit  11  of the collimator  10  is not centered on the line joining the focal spot  40  of the x-ray source  3  and a center of the active area  21  of the sensor  20 . Thus, in certain exemplary embodiments in a second step, it can be necessary to correct this offset (e.g., of the aperture  11  center position and active area  21  center position) by centering the collimator  10  relative to the sensor  20 . 
         [0038]    For the purpose of correcting the mis-alignment tilt of the collimator  10  to imaging device  1 , in embodiments of the application the collimator  10  can be movably fixed or rotatably fixed on an ensemble sliding along the first rail  91 .  FIG. 5  is a diagram that shows an exploded view of an ensemble including an exemplary carriage and an exemplary platen with fixing means according to embodiments of the application. A platen  60  can be positioned relative to a carriage  50  by a shaft  71  passing through a hole  61  of the platen  60  and a hole  51  of the carriage  50 . As described herein, in one exemplary embodiment the shaft  71  can act as a rotation axis for a small angle rotation movement of the platen  60  relative to the carriage  50 . The shaft  71  is provided with a bore  71   a  about its mid portion. A first protrusion  59  extends from the lateral face of the carriage  50 . An urging force can rotate the platen  60  relative to the carriage  50 . In one embodiment, a spring  53  is attached to a lower face of first protrusion  59  and is housed in a bore  63  of the platen  60  when the platen  60  is positioned against the carriage  50 . The force exerted by the spring  53  against the bottom of the bore  63  leads to a rotation of the platen  60  about the axis  71  relative to the carriage  50  so that an upper face  64  of the platen  60  contacts a lower face  54  of the protrusion  59  of the carriage  50 . The platen  60  is then tilted relative to the carriage  50 , as shown in  FIG. 6 . 
         [0039]    For certain exemplary embodiments, the platen  60  can be fixedly positioned to the carriage  50  by various conventional devices in an intermediate position or where the upper face  64  of the platen  60  does not contact the lower face  54  of the carriage  50 . In one exemplary embodiment, a fixing unit or a fixing device such as fixing means  72   a ,  72   b ,  82   a ,  82   b  can be provided to fix the platen  60  relative to the carriage  50  at a position in which the surfaces  54  and  64  are not abutted (e.g., against the force of the spring  53 ). Two screws  82   a  and  82   b  can penetrate through two oblong holes  62   a  and  62   b  milled on the carriage  60  and through two threaded bores  52   a  and  52   b  of the carriage  50 . Two washers  72   a  and  72   b  can be located between the screws  82   a  and  82   b  and the face of the platen  60 . As long as the screws  82   a  and  82   b  are not tightly screwed into the bores  52   a  and  52   b , the platen  60  can freely rotate relative to the carriage  50 . For example, the largest dimension (e.g., length) of the oblong holes  62   a  and  62   b  is far larger than the diameter of the screws  82   a  and  82   b  that penetrate the oblong holes. Then, the oblong holes  62   a  and  62   b  of the platen  60  can be displaced relative to the screws  82   a  and  82   b  fixed in the threaded bores  52   a  and  52   b  of the carriage  50 . On the contrary, when the screws  82   a  and  82   b  are tightly screwed in the threaded bores  52   a  and  52   b , the washers  72   a  and  72   b  are pressed against the part of the face  65  of the platen  60  surrounding the oblong holes  62   a  and  62   b . For example, the washers  72   a  and  72   b  can be chosen such that their diameter is larger than the width of the oblong holes  62   a  and  62   b . The carriage  50  and the platen  60  are then in a fixed relationship. In examples of the fixed relationship case, the relative positioning between the carriage  50  and the platen  60  may be different from the position imposed by the action of the spring  53  described above (see  FIG. 6 ) and the surface  64  of the platen  60  and the surface  54  of the carriage  50  may not be in contact as shown in  FIG. 7 . In one embodiment, any other relative position is achievable when the friction strength between the screws  82   a  and  82   b  and the face  65  of the platen  60  counterbalances the action of the spring  53 . 
         [0040]      FIG. 8  is a diagram that shows a cross section of an exemplary ensemble embodiment including a carriage and a platen that are secured to a belt and positioned on a guiding rail of a cephalometric platform, where the carriage and platen are holding a secondary collimator according to the application.  FIG. 9  shows an isometric view of the exemplary ensemble embodiment of  FIG. 8  secured to the guiding rail according to the application. The carriage  50  can include a second protrusion  57  that includes a groove  57   a  in which a belt  120  can be housed. A plate  111  can press the belt  120  against the protrusion  57  so that the belt cannot slide relative to the carriage  50 . A screw  112  can penetrate through the hole  113  of the plate  111  and into the threaded bore  58   a  of the protrusion  57  of the carriage  50  to secure the contact between the belt  120  and the carriage  50 . 
         [0041]    A guide rail  90  is positioned in a recess  56  in the rear face of the carriage  50  and the carriage  50  can be secured to the guide rail by two screws  55   a  and  55   b  (see  FIG. 5 ). The guide rail  90  slides along a rail  91  that elongates in a direction parallel to one side of the cephalometric platform  100  (see  FIG. 10 ). A stepping motor  130  or the like can produce the displacement of the belt  120  via a displacement mechanism  131 . As the belt  120  is secured to the carriage  50 , which is itself secured on the guide rail  90  that slides along the rail  91 , the motor  130  can displace the carriage  50  along the rail  91 . 
         [0042]      FIG. 11  is a diagram that shows a front view of an exemplary connection of a secondary collimator to a guide rail according to embodiments of the application. The collimator  10  can be fixed on an ensemble including the carriage  50  and the platen  60  by a long screw  59 a that passes through the hole  58  of the carriage  50  (see  FIG. 8 ), the hole  68  on the surface of the upper edge of the platen  60 , the hole  71   a  that traverses the shaft  71  and finally a threaded bore  26  in the protrusion  24  of the cover of the collimator  10 . Two notches  25   a  and  25   b  can be also provided on the protrusion  24  of the cover of the collimator  25  to engage the protrusions  66   a  and  66   b  on the surface  65  of the carriage  60  (see  FIG. 11 ). A plate  70  can press the protrusion  24  of the cover of the collimator  10  against the face  65  of the platen  60 . In this way, the collimator  10  is rigidly fixed to the platen  60  and consequently has the same position and/or direction as the platen  60  relative to the carriage  50 . 
         [0043]    The sensor  20  (not shown) can be fixed on an exemplary mechanism secured to a second belt  150  (see  FIG. 10 ). This exemplary mechanism can slide along the rail  92  by actuation of the belt  150  by the stepping motor  130 . The exemplary mechanism can be conceived or formed in such a way that the sensor  20  is always vertical, that is to say orthogonal to the plane of the cephalometric platform  100 . 
         [0044]      FIG. 10  is a diagram that shows an exemplary detachable tilting device embodiment attached to a cephalometric platform according to the application.  FIG. 12  is a diagram that shows an isometric view of the exemplary detachable tilting device embodiment of  FIG. 10 . As shown in  FIG. 10 , tilting unit or tilting means  200  can cause or determine a tilt of the collimator  10  and the collimator slit  11  relative to the active area  21  of the sensor  20  can include a thin metallic frame with an upper curved surface  201  provided with two notches  202   a  and  202   b  and at least one protrusion  203  with a curved extremity  204  ( FIG. 12 ). A stop  205 , for example made of plastic, can be integral or fixed to the surface of the curved extremity  204 . According to one exemplary alignment method, the tilting means  200  can be fixed to a prescribed portion, edge or ridge of the cephalometric platform  200  for the purpose of aligning the collimator  10  in such a way that the stop  205  intersects the trajectory of the collimator  10  when the collimator  10  is translated by the actuation of the stepping motor  130 . 
         [0045]      FIG. 13  is a diagram that shows a rear view of a secondary collimator and an exemplary detachable tilting device embodiment at a start position of the collimator sliding movement towards a rotation point or device according to the application.  FIG. 14  is a diagram that shows a rear view of the secondary collimator and an exemplary detachable tilting device embodiment at the end position of the collimator in his sliding movement with a contact between the rotation device and the collimator according to the application. 
         [0046]    In certain alignment methods and/or apparatus embodiments according to the application, the collimator  10  is translated from a first position away from the stop  205  having a tilt in a first orientation, that is with the direction of the slit  11  of the collimator  10  forming a positive angle with the vertical direction  220  (see  FIG. 13 ). During this translation of the collimator  10  (e.g., in the direction toward the stop  25 ), the fixing means  72   a ,  72   b ,  82   a  and  82   b  is not tightly fixed, the faces  54  and  64  are in contact. It must be reminded that the vertical direction  220  is also the direction of the active area  21  of the sensor  20 . This initial tilt is created by the action of the spring  53  that tilts the platen  60  and the collimator  10  relative to the carriage  50  (see  FIG. 6 ). First, the collimator  10  is translated towards the stop  205 . Second, the edge of the collimator  10  contacts the stop  25 , and a torque is applied on the collimator  10  and hence on the platen  60  that opposes the action of the spring  53 . The tilt of the slit  11  of the collimator  10  relative to the vertical direction  220  (or the sensor direction, which can be horizontal or another prescribed orientation) progressively decreases as the collimator  10  continues to be progressively translated in the direction towards the stop  205 . The tilt or angle of the slit  11  of the collimator  10  reaches the zero value and then becomes negative when the collimator  10  keeps on being translated (see  FIG. 14 ). 
         [0047]    Meanwhile, during the translation of the collimator  10 , the x-ray source emits an x-ray beam and blank images (e.g., projection images) can be captured at each position (e.g., step of the stepping motor) of the collimator  10 . The area  45  of the surface of the active area  21  of the sensor  20  that is impinged by the x-ray beam  44  that passes through the tilted collimation slit  11  can be stored at each position of the collimator  10  during translation. In particular, each image ( FIGS. 15 a -15 c   ) is associated to a known position of the collimator  10  (e.g., expressed in a number of steps carried out by the stepping motor  130 ). The surface  45  on the image can be characterized by an edge  46  that forms an angle with the edge  21   a  of the active surface  21  of the sensor  20 . It will be obvious for the man skilled in the art that this angle is correlated with the angle formed between the direction of the slit  11  of the collimator  10  and the vertical direction  200 , which is the same as the direction of the active surface area  21  of the sensor  20 . 
         [0048]    In certain exemplary embodiments, an initial tilt of the collimation slit  11  can be −10° relative to vertical and a final tilt of the collimation slit  11  can be +10° relative to vertical and at least  20  exposures can be obtained over the 20° range from the initial to final position so that at least 0.5° increments in tilt can be evaluated. Alternatively, the range from the initial to final position can be 10°, 15° or 30°. Further, in some embodiments, exemplary increments in tilt can be between 0.25° to 1°. In addition, the number of exposures during translation can be a few as 5-7 exposures or up to 40 or more exposures. 
         [0049]    In one exemplary embodiment, the desired or best alignment of the collimator  10  and sensor  20  among the plurality of positions (e.g., projection images or frame) during translation can be determined. For example, an algorithm can automatically calculate the angle of the left and right edges of the irradiated surface on each frame. This edge can correspond to the sensor border  21   a  or to the edge  46  of the impinged surface. The angles absolute values can be summed to retrieve the image with the minimum angle value, that is the closest value to zero (see  FIG. 15 b   ). This image corresponds to a selected alignment of or the best alignment of the collimator  10  and sensor  20 . In an embodiment using the stepping motor, the collimator  10  can be repositioned at this precise position that corresponds to the selected or correct alignment of the slit  11  of the collimator  10  with the active elongated area  21  of the sensor  20 , with the collimator  10  being still submitted to the torque created by the contact with the stop  25 . Then, the position of the collimator  10  can be fixed at the selected or correct alignment of the slit  11 . Alternatively, the collimator  10  can be continuously translated or horizontally moved while pulsed or a series of short exposures are performed by the x-ray source  3 , images captured by the sensor  10  and the position of the collimator  10  is recorded or detected at each exposure. For example, in one embodiment, a position of the collimator  10  during translation can be remotely sensed (e.g., emitters on the collimator  10  and sensors on the extra-oral imaging device  1 , remote cameras or the like). 
         [0050]    In one embodiment, to fix the angular position of the collimator  10 , it is then necessary to screw tightly the screws  72   a  and  72   b  (see  FIG. 5 ) so that the friction between the washers  82   a  and  82   b  on the surface of the platen surrounding the oblong holes  62   a  and  62   b  counterbalances the force exerted by the spring  53  on the platen. Then, the tilting means  200 , which is preferably used only during the exemplary alignment processes, can be removed from the edge of the platform  100 . 
         [0051]    Once the tilt alignment is achieved, an additional or last step includes aligning the center of the slit  11  of the collimator  10  with the center of the active surface area  21  of the sensor  20  according to methods and/or apparatus known from the related art. Alternatively, the aligning the center of the slit  11  of the collimator  10  with the center of the active surface area  21  of the sensor  21  according to methods known from the related art can be performed before the exemplary tilt alignment embodiments according to the application described herein. Then, the image  45  is centered and aligned on the active surface  21  on the sensor  20  as shown in  FIG. 16 . 
         [0052]    In certain exemplary embodiments, the stop  205  can be above the aperture  11  of the collimator  10 . Alternative embodiments place the stop  205  near the middle of the aperture  11  of the collimator  10 . In one exemplary embodiment, the stop  205  can be near the bottom or below the aperture  11  of the collimator  10 , which can provide increased granularity or smaller sized increments of tilt during translation of the collimator  10  during alignment. 
         [0053]    Consistent with exemplary embodiments of the present application, a computer program utilizes stored instructions that perform on image data that is accessed from an electronic memory. As can be appreciated by those skilled in the image processing arts, a computer program for operating the imaging system in an exemplary embodiment of the present application can be utilized by a suitable, general-purpose computer system, such as a personal computer or workstation. However, many other types of computer systems can be used to execute the computer program of the present application, including an arrangement of networked processors, for example. The computer program for performing exemplary methods/apparatus of the present application may be stored in a computer readable storage medium. This medium may comprise, for example; magnetic storage media such as a magnetic disk such as a hard drive or removable device or magnetic tape; optical storage media such as an optical disc, optical tape, or machine readable optical encoding; solid state electronic storage devices such as random access memory (RAM), or read only memory (ROM); or any other physical device or medium employed to store a computer program. The computer program for performing exemplary methods/apparatus of the present application may also be stored on computer readable storage medium that is connected to the image processor by way of the internet or other network or communication medium. Those skilled in the art will further readily recognize that the equivalent of such a computer program product may also be constructed in hardware. 
         [0054]    It should be noted that the term “memory”, equivalent to “computer-accessible memory” in the context of the present disclosure, can refer to any type of temporary or more enduring data storage workspace used for storing and operating upon image data and accessible to a computer system, including a database, for example. The memory could be non-volatile, using, for example, a long-term storage medium such as magnetic or optical storage. Alternately, the memory could be of a more volatile nature, using an electronic circuit, such as random-access memory (RAM) that is used as a temporary buffer or workspace by a microprocessor or other control logic processor device. Display data, for example, is typically stored in a temporary storage buffer that is directly associated with a display device and is periodically refreshed as needed in order to provide displayed data. This temporary storage buffer is also considered to be a type of memory, as the term is used in the present disclosure. Memory is also used as the data workspace for executing and storing intermediate and final results of calculations and other processing. Computer-accessible memory can be volatile, non-volatile, or a hybrid combination of volatile and non-volatile types. 
         [0055]    It will be understood that the computer program product of the present application may make use of various image manipulation algorithms and processes that are well known. It will be further understood that the computer program product embodiment of the present application may embody algorithms and processes not specifically shown or described herein that are useful for implementation. Such algorithms and processes may include conventional utilities that are within the ordinary skill of the image processing arts. Additional aspects of such algorithms and systems, and hardware and/or software for producing and otherwise processing the images or co-operating with the computer program product of the present application, are not specifically shown or described herein and may be selected from such algorithms, systems, hardware, components and elements known in the art. In the description herein, exemplary embodiments of the application can be described as a software program. Those skilled in the art will recognize that the equivalent of such software may also be constructed in hardware. Because image manipulation algorithms and systems are well known, the present description will be directed in particular to algorithms and systems forming part of, or cooperating more directly with, the method in accordance with the present invention. Other aspects of such algorithms and systems, and hardware and/or software for producing and otherwise processing the image signals involved therewith, not specifically shown or described herein may be selected from such systems, algorithms, components and elements known in the art. 
         [0056]    A computer program product may include one or more storage medium, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method according to the present invention. 
         [0057]    The methods described above may be described with reference to a flowchart. Describing the methods by reference to a flowchart enables one skilled in the art to develop such programs, firmware, or hardware, including such instructions to carry out the methods on suitable computers, executing the instructions from computer-readable media. Similarly, the methods performed by the service computer programs, firmware, or hardware are also composed of computer-executable instructions. 
         [0058]    As described herein, portions of some exemplary embodiments have been connected or joined together using screws. However, the application is not intended to be so limited as various example of fasteners can be used such as but not intended to be limited to mechanical fasteners like anchors, bolts, hardware, nails, nuts, pins, clips, rivets, rods, sockets, clamps, hangers, but also non-mechanical fasteners like adhesives or welds or permanent fasteners. Similarly, exemplary embodiments describe fixing means to couple an exemplary carriage to an exemplary platen. Exemplary fixing means herein can preferably provide a first engagement and a second engagement between the carriage  50  and platen  60 . The first engagement by the fixing means between the carriage  50  and platen  60  can allow movement such as but not limited to rotation therebetween while an elastic or urging force can also be provided during the first engagement to set a prescribed rotation (e.g., 10° rotation therebetween) or prescribed position. The second engagement by the fixing means between the carriage  50  and platen  60  does not allow movement therebetween but sets a specific spatial or positional relationship therebetween and in some cases overcoming an elastic or urging force that can be maintained during the second engagement. 
         [0059]    One conventional method to align the center of the slit  11  of the collimator  10  with the center of the active surface area  21  of the sensor  20  (e.g., sagittal plane of the skull must be parallel to the plane of the sensor at the time of the imaging and orthogonal to the median line of the x-ray beam) will now be described. When a cephalometric imaging apparatus is first installed in a dental site by a technician, it is necessary to adjust the position of the whole cephalometric imaging module, comprising the x-ray sensor and a patient holder, relative to the x-ray source, prior to any cephalometric imaging of patients. Conventionally, at least two radiopaque markers are located on the patient holder and a first x-ray control image of the patient holder (without any patient) is carried out. If the images of the at least two markers superimpose on the x-ray image, the cephalometric module is conveniently or correctly positioned relative to the x-ray source. On the contrary, if the images of the two markers do not superimpose, the cephalometric module is misaligned relative to the x-ray source and needs to be repositioned before capturing a second control image or additional control images. Note that the technician who installs the cephalometric imaging device does not know, at the time he changes the adjustment of the cephalometric module, whether the new adjustment is correct. Only subsequent control images taken after adjustment will give an assessment of the quality of the adjustment. Accordingly, the cephalometric installation requires an adjustment process including a repeated, back and forth method of (i) successive adjustments of the cephalometric module to the x-ray source and (ii) successive assessments by taking a follow-up control image. 
         [0060]    The invention has been described in detail, and may have been described with particular reference to a suitable or presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, exemplary tilting unit embodiments can be reciprocally moved between a retracted position and an alignment position in contrast to being detachable. In addition, exemplary apparatus and/or method embodiments according to the application have been described relative to a combined cephalometric, panoramic and computed tomography dental imaging apparatus, but are intended to be applicable to stand-alone cephalometric imaging apparatus or cephalometric imaging apparatus with any additional mode(s) of operation or functionality. The presently disclosed exemplary embodiments are therefore considered in all respects to be illustrative and not restrictive. 
         [0061]    In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. 
         [0062]    Exemplary embodiments according to the application can include various features described herein (individually or in combination). 
         [0063]    While the invention has been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the invention can have been disclosed with respect to one of several implementations, such feature can be combined with one or more other features of the other implementations as can be desired and advantageous for any given or particular function. The term “at least one of” is used to mean one or more of the listed items can be selected. The term “about” indicates that the value listed can be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.