Abstract:
A x-ray diagnostic apparatus and methods perform Real-Time Digital Radiography with particular application in dental x-ray imaging modalities, such as Orthopantomography, Scannography, Linear Tomography and Cephalography, by using a versatile and robotized mechanical structure, featuring projection movements in the required a real range and automatic adaptation of the same mechanical structure to serve the various x-ray imaging modalities foreseen.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Orthopantomography, Scannography, Linear Tomography and Cephalography are complementary radiographic techniques, often combined in a single equipment, of widespread use in dental radiology to obtain respectively a comprehensive survey of the maxillo-facial complex, tomographic views of selected anatomical districts under transversal or axial projections, and cranial views under multiple projections, supporting the diagnosis in the dental prevention, restoration and follow up.  
           [0002]    Orthopantomography aims to produce a radiographic image of a curved plane approximating the patient jaws, with blurring of the anatomical structures laying outside a narrow layer around the predesignated curved plane, by using the relative movement of the radiographic film versus the rotation of the x-ray source to generate the layer forming effect.  
           [0003]    Scannography has a layer forming process similar to Orthopantomography, where the object is typically laying on a flat plane. It is practically used to produce axial or transverse views of specific anatomical districts, such as the jaw, the joints and the sinus.  
           [0004]    Linear Tomography is an alternative technique, using the classic linear tomographic layer forming projection. It is practically used to produce axial or transverse views of specific anatomical districts in the jaw.  
           [0005]    Cephalography is a stationary radiographic technique, aiming to produce radiographic images of the cranial complex under various projections, with minimum magnification and geometrical distortion.  
           [0006]    For all the indicated radiographic modalities the real-time digital x-ray image acquisition is nowadays a more and more demanded feature. It provides instant image acquisition with reduced x-ray dosage, by taking advantage of the improved performances and reduced costs provided by the modem image imager technology. It also allows safer and cleaner operation, by removal of the film processing and related chemicals.  
           [0007]    Both in conventional and digital modality, performing the radiographic techniques above typically requires a mechanical structure capable of performing orbital movements around the patient with simultaneous translation of the rotational centre.  
           [0008]    A first difference is that in conventional Panoramic Radiography and Scannography the x-ray film is simultaneously translated at a speed such to obtain the blurring of the anatomical structures laying outside of the plane of interest, while in real time digital applications the x-ray film is replaced by the x-ray imager and special electronic techniques are used to produce the same blurring effect.  
           [0009]    A second difference is that in conventional Cephalography and Linear Tomography a stationary x-ray film is used, while in real-time digital applications the stationary x-ray film can be replaced by a stationary x-ray imager.  
           [0010]    Alternatively, to significantly reduce the system cost, a linearly shaped x-ray imager will be preferably used, and the image acquisition will be performed by using a horizontal or vertical scanning technique.  
           [0011]    Another important difference is that, due to the high cost of the x-ray imager, in real-time digital applications it will be very desirable to have an apparatus and method to relocate the x-ray imager, either manually or automatically, from the Panoramic to the Cephalographic position.  
           [0012]    The fundamental concept on which this invention is based was described in prior art application (U.S. Pat. No. 4,985,907), where the roto-translatory system is disclosed realized by two independent translations movements in a plane and one independent rotation movement about an axis perpendicular to that plane. The present invention further expands this concept, by disclosing the new apparatuses and methods required for the real-time digital implementation of the indicated radiographic modalities.  
           [0013]    Other prior art (U.S. Pat. No. 4,741,007) describes apparatus and methods in which the roto-translatory movement is realised by means of two pivot shafts placed at a constant distance from each other, using a guide groove and an active actuator.  
           [0014]    Further prior art (U.S. Pat. No. 5,012,501) describes apparatus and methods in which a variety of orbital movements is produced by using a first drive for the rotational movement, a second drive for the linear translation of the rotation centre, and a selector for selecting the direction of the linear motion.  
           [0015]    More recent prior art (WO 99/17659) describes apparatus and methods in which pivot shafts connecting multiple body parts are driven by active actuators in a SCARA arrangement, allowing a variety of projection movements as required for various dental x-ray imaging modalities.  
           [0016]    The concept of the three independent roto-translatory movements disclosed in prior art (U.S. Pat. No. 4,985,907) has proven its flexibility in producing multiple orbital projections by simple adjustment of the software programming data, and can be advantageously used for the generation of the orbital movements required for OrthoPanTomography, Scannography, and Linear Tomography, both in Conventional and Real-Time Digital Radiography.  
           [0017]    The main difference will be that in Real-Time Digital Radiography the film cassette with its independent drive is removed, and is replaced by the x-ray imager having an active area of a size equivalent to the x-ray field at the film plane as used in Conventional Radiography.  
           [0018]    However, it will be the purpose of this invention to further exploit the basic concept in order to implement the following desirable features:  
           [0019]    Perform Real-Time Digital Cephalography by means of horizontal, vertical or rotatory scanning movements, allowing at the same time ergonomic and reproducible immobilisation of the patient by suitable positioning system.  
           [0020]    Perform automatic relocation of the x-ray imager between the Panoramic and Cephalographic positions, in order to allow use of the same imager in both imaging modalities.  
         SUMMARY OF THE INVENTION  
         [0021]    The object of the invention is a x-ray apparatus providing a robotized mechanical structure capable of performing Real-time Digital Radiography with particular application in Orthopantomography, Scannography, Linear Tomography and Cephalography.  
           [0022]    In Real-Time Digital Orthopantomography, Scannography and Linear Tomography the apparatus of the invention will be based on the fundamental robotic concept disclosed in U.S. Pat. No. 4,985,907, with the difference that the film cassette with its independent drive will be removed, and the x-ray imager will be introduced.  
           [0023]    Various kinds of x-ray imager will be allowed, and the active area of the x-ray imager will be of a size equivalent to the x-ray field at the film plane as used in Conventional Radiography.  
           [0024]    In Real-Time Digital Cephalography a first approach may be to replace the conventional radiographic film by a x-ray imager of equivalent size.  
           [0025]    Also in this case various kinds of x-ray imager may be used, based on existing technologies well known to those skilled in the art, such as CCD or CMOS or Amorphous Silicon readout devices optically coupled with scintillator screens or electrically coupled with direct x-ray detection screens.  
           [0026]    This approach may become convenient in the future, but is very expensive at the present status of technology and does not offer today an economic solution for the dental practice application.  
           [0027]    The alternative approach for Real-Time Digital Cephalography is to implement the radiographic image acquisition by a scanning movement, either in the horizontal or vertical direction, or rotatory.  
           [0028]    It will allow use of a linear shaped x-ray imager with reduced active area, so offering a cost effective solution for the implementation of the Real-Time Digital Cephalography.  
           [0029]    The robotic solution shall be usefully complemented by a mechanism performing automatic relocation of the x-ray imager between the Panoramic and Cephalographic positions.  
           [0030]    The purpose is to allow in a simple and effective way the use of the same x-ray imager in all the foreseen imaging modalities, with evident positive impact on the overall system cost.  
           [0031]    An innovative approach for Real-Time Digital Cephalography is also illustrated, where the same rotating arm conventionally used for panoramic technique is translated according to a predefined path in order to project from a virtual rotating centre the linear shaped sensor and build up, by using a geometric correction software algorithm, the cephalographic image acquisition by a scanning movement.  
           [0032]    The invention is particularly advantageous in dental radiography, where the outlined features find immediate application, but it could also be advantageously employed in other medical and non-medical applications having similar requirements.  
           [0033]    Here following is a description in greater detail of the invention, based on the exemplary embodiment illustrated in the attached drawings.  
       
    
    
     DESCRIPTION OF DRAWINGS AND TABLES  
       [0034]    [0034]FIG. 1 is a diagram showing an exemplary system dedicated to dental application  
         [0035]    [0035]FIG. 2 is;  
         [0036]    [0036]FIG. 3 is;  
         [0037]    [0037]FIG. 4 is;  
         [0038]    [0038]FIG. 5, 5 a ,  5   b ,  5   a ′,  5   b ′ are;  
         [0039]    [0039]FIG. 6, 6 a ,  6   b ,  6   a ′,  6   b ′ are;  
         [0040]    [0040]FIG. 7, 7 a ,  7   b ,  7   a ′,  7   b ′ are;  
         [0041]    [0041]FIG. 8, 8 a ,  8   b ,  8   a ′,  8   b ′ are; 
     
    
     DETAILED DESCRIPTION  
       [0042]    The system is a representative dental x-ray diagnostic system performing Real-time Digital Radiography in Orthopantomography, Scannography, Linear Tomography and Cephalography.  
         [0043]    For those skilled in the art, it is intended that:  
         [0044]    Orthopantomography is a narrow beam scanning technique aiming to reproduce in a single radiographic view the whole or part of a curve plane approximating the patient jaw, using layer forming methods by which the points laying in the target plane are reproduced on the same point of the radiographic image, while points laying outside the target plane are blurred out.  
         [0045]    Scannography is a narrow beam scanning technique aiming to reproduce in a single radiographic view the whole or part of a flat plane approximating specific anatomical regions (such as the jaw, the joints, the sinus), using layer forming methods by which the points laying in the target plane are reproduced on the same point of the radiographic image, while points laying outside the target plane are blurred out.  
         [0046]    Linear tomography is a wider beam radiographic technique, using the classic linear tomographic layer forming projection, where by the combined movement of x-ray source and x-ray imager around the object, only the points laying in the target plane are reproduced on the same point of the radiographic image, while points laying outside the target plane are blurred out.  
         [0047]    Cephalography is a stationary radiographic technique, where the cranial complex is exposed under various projections, with minimum magnification and geometrical distortion.  
         [0048]    The apparatus of the invention is based on the robotic concept already disclosed in U.S. Pat. No. 4,985,907, with the difference that the film cassette with its independent drive is removed, and the x-ray imager is introduced.  
         [0049]    Additionally it proposes various arrangements for performing Real-Time Digital Cephalography either by a single large area x-ray imager, or by horizontal, vertical or rotational scanning with a linear shaped x-ray imager.  
         [0050]    Finally it describes suitable mechanisms for the automatic relocation of the x-ray imager from Panoramic to Cephalographic positions.  
         [0051]    [0051]FIG. 1 illustrates the most general arrangement of the system and its main mechanical and electrical components.  
         [0052]    The base  1  supports the whole apparatus. Frame  2  slides vertically along the base and is provided with an independent drive  2   a  for the control of the vertical movement. The vertical movement is used during patient positioning, for the vertical adjustment to the patient height, and may also be used for vertical scanning in the relevant Cephalographic arrangement.  
         [0053]    The rotary unit  3  is connected to the Frame  2  by the Cinematic Assembly  4 . It supports the x-ray source  11  at one end, and the x-ray imager  6  at the other end.  
         [0054]    The x-ray imager  6  is dedicated to the image acquisition in Panoramic Radiography, Scannography and Linear Tomography.  
         [0055]    The x-ray source  11  provides the x-ray generation and includes the x-ray tube and the focal spot from which the x-ray beam generates.  
         [0056]    A primary x-ray collimator  5  is attached to the output port of the x-ray source  11 , providing limitation of the radiation incident on the x-ray imagers.  
         [0057]    Preferably the x-ray collimator will be of the motorised type, operated by the independent active actuator  5   a  under micro computer control.  
         [0058]    The x-ray imager  7  is dedicated to the image acquisition in Cephalography. It is rigidly attached, by an arm or the like, to the frame  2 . Alternatively it may be attached to the rotary frame  3 , in case that the configurations adopting automatic sensor relocation as later described are used.  
         [0059]    The x-ray imager is also provided with an independent active actuator  7   a , to be used in configurations where the linear movement of the same x-ray imager is required during a scanning process, as later described.  
         [0060]    A secondary x-ray collimator  8  is attached to frame  2 . Alternatively it may be attached to the rotary frame  3  or to an independent support, in cases where configurations adopting automatic sensor relocation as later described are used.  
         [0061]    It is provided with an actuator  8   a  driving the movement of the same collimator aligned with the x-ray beam during a scanning process under micro computer control, as later described.  
         [0062]    The actuator  8   a  may be independent or mechanically controlled by the actuator  7   a  of the x-ray imager.  
         [0063]    A first patient positioning system  10  rigidly attached to the frame  2  is provided for Panoramic Radiography, Scannography and Linear Tomography, while a second patient positioning system  9 , also rigidly attached to the frame  2 , is provided for Cephalography.  
         [0064]    In alternative arrangements, where the scanning process is used, the patient positioning system  9  used in Cephalography may be independently attached either to the base frame  1 , or to the floor, or to the wall, and be provided with an independent actuator, either active or not, for the adjustment to the patient heigth.  
         [0065]    In other alternative arrangements, where the automatic sensor relocation is used as explained later, the patient positioning system  9  used in Cephalography may be attached to the rotary frame  3 , and be provided with an independent active actuator  9   a , allowing its repositioning relative to its support frame in order to maintain a firm patient position during a horizontal or vertical scanning process where the movement of the same support frame is involved.  
         [0066]    [0066]FIG. 2 illustrates the detail of the Cinematic Assembly  4 .  
         [0067]    The Cinematic Assembly  4  implements the robotic concept, by providing 3 independent axis for the rotation R, the X linear movement, and the Y linear movement.  
         [0068]    The X linear axis is composed by the motor drive  4   a  rigidly connected to the frame  2 , and the linear bearing  4   b.    
         [0069]    The Y linear axis is composed by the motor drive  4   c  rigidly connected to the support  4   d , and the linear bearing  4   e.    
         [0070]    The R (rotation) axis is composed by the motor drive  4   f  rigidly connected to the support  4   g , and the circular bearing  4   h.    
         [0071]    The x-ray imagers  6  and  7  can be of various kinds according to the state of the art.  
         [0072]    The x-ray imager assembly construction will be based on existing technologies, and will typically consist of one or more sensor devices, each providing a detector modality, optically or electrically coupled to a readout device.  
         [0073]    The detection modality can be a scintillating screen converting x-rays into light, hence requiring optical coupling to the readout device, or it can be other direct detector materials (such as CdTe, CdZnTe, HPGe,HgI 2 ,GaAs,PbI 2 ) providing direct conversion of x-rays to electric charge, hence requiring electrical bonding to the readout device pixels.  
         [0074]    The readout layer is a semiconductor device whose fabrication is based on various available technologies, among which CCD, CMOS or Amorphous Silicon, well known to those skilled in the art.  
         [0075]    [0075]FIG. 3 shows a scheme for the control system for an apparatus according to the invention.  
         [0076]    One or more microcontrollers  16  and associated memory  17  form the system micro computer, feeding the independent motor drives X,Y,R with cinematic profiles data associated to the specific orbital projection.  
         [0077]    It also controls the actuator  7   a  associated with the x-ray imager  7 , the actuator  5   a  associated with the primary x-ray collimator  5 , the actuator  8   a  associated with the secondary x-ray collimator  8 , the actuator  9   a  associated with the patient positioning system, and the actuator  2   a  associated with the vertical slide of frame  2 , for the movements required during the normal operation and during the various scanning processes foreseen in Cephalography.  
         [0078]    In FIG. 4, 4 a ,  4   b  arrangements are shown where the Real-Time Digital Cephalography is implemented by replacing the conventional radiographic film by a x-ray imager  7  of equivalent size.  
         [0079]    In all the arrangements the primary x-ray collimator  5  is kept steady, and there is no secondary collimator.  
         [0080]    In FIG. 4 is a first arrangement where the Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended. The arm is rigidly connected to the frame  2 .  
         [0081]    In the alternative arrangements of FIG. 4 a ,  4   b , a single large area x-ray imager can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0082]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0083]    In FIG. 4 a  an arrangement is illustrated, where the x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm, either provided with an active actuator  12  or to be manually actuated.  
         [0084]    The Cephalographic patient positioning system  9  is supported on a separate arm rigidly connected to the frame  2 .  
         [0085]    In FIG. 4 b  another arrangement is illustrated, where the x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a folding arm, either provided with an active actuator  12  or to be manually actuated.  
         [0086]    The Cephalographic patient positioning system  9  is also supported on a separate arm rigidly connected to the frame  2 .  
         [0087]    In FIG. 5, 5 a ,  5   b ,  5   a ′,  5   b ′ arrangements are shown where the Real-Time Digital Cephalography is implemented by a scanning process in the horizontal direction achieved by a movement of the x-ray source  11 , using a narrow x-ray beam and a linear shaped x-ray imager having an active area of a length approximately corresponding to the minimum useful heigth of the x-ray field size at the film plane used in Conventional Cephalography.  
         [0088]    In these arrangements software post-processing of the acquired image will be required to correct the magnification distortions in the Y direction.  
         [0089]    In FIG. 5 a first arrangement is illustrated where the x-ray source  11  and the primary x-ray collimator  5  are simultaneously and linearly moved in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0090]    The secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  8   a  and  7   a , under microcomputer control during the horizontal scanning sequence.  
         [0091]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended. The arm is rigidly connected to the frame  2 .  
         [0092]    In this arrangement there are several other alternative movements of the x-ray source  11  which can advantageously used to realize the scanning process. By utilizing the roto-translating capabilities of the cinematic unit, the x-ray source  11  can perform a rotational movement around its focal point, otherwise it can move along a trajectory characterized in having a constant distance between the focal point and the x-ray sensor, otherwise more generally it can perform a projection from a predefined virtual centre of rotation.  
         [0093]    Still referring to FIG. 5, arrangements are here following illustrated where the Real-Time Digital Cephalography is implemented by a scanning process in the horizontal direction achieved by a roto-translating movement of the x-ray source  11 , using a narrow x-ray beam and the same linear shaped x-ray imager  6  used for Panoramic Radiography, Scannography and Linear Tomography.  
         [0094]    In such case the active area of the x-ray imager may require an additional length in order to cover all the anatomical regions of interest.  
         [0095]    In a first arrangement the rotary frame  3  performs a linear trajectory in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0096]    In other more complex arrangements, by utilizing the roto-translating capabilities of the cinematic unit, the rotary frame  3  can perform roto-translating scanning trajectories where the object is illuminated from a predefined virtual centre of irradiation among which those depicted in FIG. 5.  
         [0097]    In all these arrangements software post-processing of the acquired image will be required to perform geometric correction of the magnification distortions.  
         [0098]    In the alternative arrangements of FIG. 5 a ,  5   b ,  5   a ′,  5   b ′, the x-ray imager  7  can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0099]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0100]    In FIG. 5 a  an arrangement is illustrated where the x-ray source  11 , the primary collimator  5 , the secondary collimator  8 , and the x-ray imager  7  are simultaneously and linearly moved in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0101]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended, while an independent active actuator  9   a shall be foreseen providing movement relative to the support arm in opposition to the scanning movement under microcomputer control, in order to maintain the patient in a firm position.  
         [0102]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0103]    In FIG. 5 b  an arrangement is illustrated where the x-ray source  11 , the primary collimator  5 , the secondary collimator  8 , and the x-ray imager  7  are simultaneously and linearly moved in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0104]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended, while an independent active actuator  9   a  shall be foreseen providing movement relative to the support arm in opposition to the scanning movement under microcomputer control, in order to maintain the patient in a firm position.  
         [0105]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.  
         [0106]    In FIG. 5 a ′ an arrangement is illustrated where the x-ray source  11 , the primary collimator  5 , and the x-ray imager  7  are simultaneously and linearly moved in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0107]    The secondary x-ray collimator  8  is synchronously moved by its actuator  8   a  and kept aligned with the x-ray beam under microcomputer control during the scanning process.  
         [0108]    The Cephalographic patient positioning system  9  is kept steady during the scanning process, supported by an arm rigidly connected to the frame  2 .  
         [0109]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0110]    In FIG. 5 b ′ an arrangement is illustrated where the x-ray source  11 , the primary collimator  5 , and the x-ray imager  7  are moved linearly in the Y direction, by acting on the Y axis under microcomputer control during the scanning sequence.  
         [0111]    The secondary x-ray collimator  8  is synchronously moved by its actuator  8   a  and kept aligned with the x-ray beam under microcomputer control during the scanning process.  
         [0112]    The Cephalographic patient positioning system  9  is kept steady during the scanning process, supported by an arm rigidly connected to the frame  2 .  
         [0113]    The x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.  
         [0114]    In FIG. 6, 6 a ,  6   b ,  6   a ′,  6   b ′ arrangements are shown where the Real-Time Digital Cephalography is implemented by a scanning movement in the horizontal direction of the primary x-ray collimator  5 , using a narrow x-ray beam and a linear shaped x-ray imager having an active area of a length approximately corresponding to the minimum useful height of the x-ray field size at the film plane used in Conventional Cephalography.  
         [0115]    In this case no software post-processing of the acquired image will be required.  
         [0116]    In FIG. 6 an arrangement is illustrated where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis under microcomputer control during the horizontal scanning sequence.  
         [0117]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended. The arm is rigidly connected to the frame  2 .  
         [0118]    In the alternative arrangements of FIG. 6 a ,  6   b ,  6   a ′,  6   b ′, the x-ray imager  7  can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0119]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0120]    In FIG. 6 a  an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the horizontal scanning sequence.  
         [0121]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager  7  is suspended and is kept steady during the scanning process.  
         [0122]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0123]    In FIG. 6 b  an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the horizontal scanning sequence.  
         [0124]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended and is kept steady during the scanning process.  
         [0125]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.  
         [0126]    In FIG. 6 a ′ an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the horizontal scanning sequence.  
         [0127]    The secondary x-ray collimator  8  and the Cephalographic patient positioning system  9  are supported on an arm rigidly connected to the frame  2 . The independent actuator  8   a  shall be foreseen providing movement of the secondary collimator  8  relative to the arm.  
         [0128]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0129]    In FIG. 6 b ′ an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the horizontal scanning sequence.  
         [0130]    The secondary x-ray collimator  8  and the Cephalographic patient positioning system  9  are supported on an arm rigidly connected to the frame  2 . An independent actuator  8   a  shall be foreseen providing movement of the secondary collimator  8  relative to the arm.  
         [0131]    The x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.  
         [0132]    In FIG. 7, 7 a ,  7   b ,  7   c  arrangements are shown where the Real-Time Digital Cephalography is implemented by a scanning movement in the vertical direction of the Z-axis, using a narrow x-ray beam and a linear shaped x-ray imager having an active area of a length approximately corresponding to the minimum useful width of the x-ray field size at the film plane used in Conventional Cephalography.  
         [0133]    In this arrangement a software post-processing of the acquired image will be required to correct the magnification distortion in the Z direction.  
         [0134]    In FIG. 7 an arrangement is illustrated where the x-ray source  11 , the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are simultaneously and linearly moved in the vertical direction, by acting on the Z axis under microcomputer control during the scanning sequence.  
         [0135]    The Cephalographic patient positioning system  9  is rigidly connected to the base, to the wall, or to the floor (support  14 ), providing independent adjustment, either manual or motorized by the actuator  14   a  of the patient height.  
         [0136]    In FIG. 7 a  an arrangement is illustrated where the x-ray source  11 , the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are simultaneously and linearly moved in the vertical direction, by acting on the Z axis under microcomputer control during the scanning sequence.  
         [0137]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended, where an independent active actuator  9   a  shall be foreseen providing movement relative to the supporting arm in opposition to the scanning movement, in order to maintain the patient in a firm position.  
         [0138]    In the alternative arrangements of FIG. 7 b ,  7   c , the x-ray imager  7  can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0139]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0140]    In FIG. 7 b  an arrangement is shown, where the x-ray source  11 , the primary x-ray collimator  5 , and the x-ray imager  7  are simultaneously and linearly moved in the vertical direction, by acting on the Z axis under microcomputer control during the scanning sequence.  
         [0141]    The Cephalographic patient positioning system  9  and the secondary x-ray collimator  8  are rigidly connected to the base, to the wall, or to the floor, by a support  14 , providing independent adjustment of the patient height, either manual or motorized by the actuator  14   a.    
         [0142]    The secondary x-ray collimator  8  is synchronously moved, aligned with the x-ray beam, by the independent actuator  8   a  under microcomputer control during the scanning sequence.  
         [0143]    The x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated. After relocation by the telescopic arm, the linear shaped imager is tilted in the horizontal position by an independent actuator  13 .  
         [0144]    In FIG. 7 c  an arrangement is shown, where the x-ray source  11 , the primary x-ray collimator  5 , and the x-ray imager  7  are simultaneously and linearly moved in the vertical direction, by acting on the Z axis under microcomputer control during the scanning sequence.  
         [0145]    The Cephalographic patient positioning system  9  and the secondary x-ray collimator  8  are rigidly connected to the base, to the wall, or to the floor, by a support  14 , providing independent adjustment of the patient height, either manual or motorized by the actuator  14   a.    
         [0146]    The secondary x-ray collimator  8  is synchronously moved, aligned with the x-ray beam, by the independent actuator  8   a  under microcomputer control during the scanning sequence.  
         [0147]    The x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated. After relocation by the folding arm, the linear shaped imager is tilted in the horizontal position by an independent actuator  13 .  
         [0148]    In FIG. 8, 8 a ,  8   b  arrangements are shown where the Real-Time Digital Cephalography is implemented by a scanning movement in the vertical direction (Z-direction) of the primary x-ray collimator  5 , using a narrow x-ray beam and a linear shaped x-ray imager having an active area of a length approximately corresponding to the minimum useful width of the x-ray field size at the film plane used in Conventional Cephalography.  
         [0149]    In these arrangements no software post-processing of the acquired image will be required.  
         [0150]    In FIG. 8 an arrangement is illustrated where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using their respective actuators  5   a ,  8   a ,  7   a  under microcomputer control during the vertical scanning sequence.  
         [0151]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended. The arm is rigidly connected to the frame  2 .  
         [0152]    In the alternative arrangements of FIG. 8 a ,  8   b , the x-ray imager  7  can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0153]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0154]    In FIG. 8 a  an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using their respective actuators  5   a ,  8   a ,  7   a  under microcomputer control during the vertical scanning sequence.  
         [0155]    The Cephalographic patient positioning system  9  and the secondary x-ray collimator  8  are rigidly connected to the base, to the wall, or to the floor by the support  14 , providing independent adjustment of the patient height, either manual or motorized by the actuator  14   a.    
         [0156]    The independent actuator  8   a  provides movement of the secondary collimator  8  relative to the supporting arm.  
         [0157]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated. After relocation by the telescopic arm, the linear shaped imager is tilted in the horizontal position by an independent actuator  13 .  
         [0158]    In FIG. 8 b  an arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using their respective actuators  5   a ,  8   a ,  7   a  under microcomputer control during the vertical scanning sequence.  
         [0159]    The Cephalographic patient positioning system  9  and the secondary x-ray collimator  8  are rigidly connected to the base, to the wall, or to the floor by the support  14 , providing independent adjustment of the patient height, either manual or motorized by the actuator  14   a.    
         [0160]    The independent actuator  8   a  provides movement of the secondary collimator  8  relative to the supporting arm.  
         [0161]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated. After relocation by the folding arm, the linear shaped imager is tilted in the horizontal position by an independent actuator  13 .  
         [0162]    In FIG. 9, 9 a ,  9   b  arrangements are shown where the Real-Time Digital Cephalography is implemented by a rotatory scanning movement of the primary x-ray collimator  5 , using a narrow x-ray beam and a linear shaped x-ray imager.  
         [0163]    In these arrangements software post-processing of the acquired image will be required, in order to perform geometric correction of the magnification distortions.  
         [0164]    In FIG. 9 the arrangement is illustrated where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using their respective actuators  5   a ,  8   a ,  7   a  under microcomputer control during the rotational scanning sequence.  
         [0165]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended. The arm is rigidly connected to the frame  2 .  
         [0166]    In the alternative arrangements of FIG. 9 a ,  9   b ,  9   a ′,  9   b ′ the x-ray imager  7  can be relocated from Cephalography to Panoramic Radiography, Scannography and Linear Tomography. In this way the x-ray imager  7  takes the position and replaces the x-ray imager  6 , so achieving a remarkable reduction of the system cost.  
         [0167]    The extension movement of the apparatus may be automatically triggered and controlled by a user command or by the selection of the radiographic modality. It shall prevent collisions with the patient positioning system, and shall incorporate provision for safety release to avoid potential injury to the patient.  
         [0168]    In FIG. 9 a  the arrangement is illustrated where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the rotational scanning sequence.  
         [0169]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager  7  is suspended and is kept steady during the scanning process.  
         [0170]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0171]    In FIG. 9 b  the arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the rotational scanning sequence.  
         [0172]    The Cephalographic patient positioning system  9  is supported on the same arm where the x-ray imager is suspended and is kept steady during the scanning process.  
         [0173]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.  
         [0174]    In FIG. 9 a ′ the arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the rotational scanning sequence.  
         [0175]    The secondary x-ray collimator  8  and the Cephalographic patient positioning system  9  are supported on an arm rigidly connected to the frame  2 .  
         [0176]    The x-ray imager  7  can be relocated from Cephalographic to Panoramic position and vice versa by using a telescopic arm either provided with an active actuator  12  or to be manually actuated.  
         [0177]    In FIG. 9 b ′ the arrangement is illustrated, where the x-ray source  11  is kept steady, while the primary x-ray collimator  5 , the secondary x-ray collimator  8  and the x-ray imager  7  are synchronously moved, aligned with the x-ray beam, by using the respective drive axis,  5   a ,  8   a  and  7   a , under microcomputer control during the rotational scanning sequence.  
         [0178]    The secondary x-ray collimator  8  and the Cephalographic patient positioning system  9  are supported on an arm rigidly connected to the frame  2 .  
         [0179]    The x-ray imager  7  is relocated from Cephalographic to Panoramic position and vice versa by using a folding arm either provided with an active actuator  12  or to be manually actuated.