Abstract:
A removable radiation sensor for connecting to a panoramic dental radiation imaging system. The sensor includes a radiation sensor unit mounted in a housing. Connector bearings are positioned within the housing so as to engage with a pair of connector pins provided as part of the upright support of the imaging system. A lock pin within the housing is selectively slidable between Locked and Unlocked, and biased toward Locked. The lock includes a locking pin with a groove, and when the groove is aligned with the respective connector pin, the lock is unlocked, and that connector pin is slidable axially within the bearings. When the groove is not aligned with the connector pin, the lock is locked, the locking pin engaging with a groove formed for that purpose in the connector pin. The sensor has a field-replaceable electrical connector, to reduce maintenance cost.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to dental radiation imaging systems, and in particular to systems having a removable radiation detector so as to permit varied uses of the detector. 
         [0002]    Panoramic and cephalometric dental radiation imaging is used to obtain images of a patient&#39;s teeth and jaws. Radiation imaging is essential in providing accurate information in the diagnostic process. Imaging techniques, such as bitewing (interproximal), edentulous (toothless), full mouth series, occlusal, periapical, panoramic techniques, and others, provide information in discovering tooth decay, broken fillings, tumors, occlusal trauma, and other effects that would otherwise be unseen by the eye, whether located inside the teeth, between the teeth, or below the gum line, within the gum tissue. In general, the radiological examinations in dentistry may be classified as intraoral and extraoral, determined by where the radiation sensor is placed with respect to the mouth. 
         [0003]    In intraoral radiological examinations, the sensor is placed inside of the mouth, and used to acquire a radiation image of a limited, small region with the greatest possible level of detail. In the extraoral radiological examinations, the sensor is positioned outside of the mouth, and used to acquire a radiation image of a far larger region of the human/animal teeth, jaw, and head. In dentistry, common extraoral imaging is divided into two types. Panoramic radiation imaging shows an area, curved following more or less the mandible shape, of the whole maxillo-facial block. Cephalometric radiation imaging shows a projection, as parallel as possible, of the whole or part of the skull. And three-dimensional techniques have been introduced recently. 
         [0004]    Extraoral imaging apparatus employs techniques that aim to move the radiation source, the radiation sensor, or both, in relation to the imaged object, thru a desired trajectory, in such a way as to reveal the anatomic structure of interest and ideally to blur the artifacts from non-related radio-opaque structures, such as bones, even though the radiation energy has also been obstructed by those structures. The goal is to produce a radiation image that meets quality criteria, such as showing undistorted anatomic shapes (constant size and the same magnification in both horizontal and vertical direction, orthogonally of the radiation beam) with uniform contrast and enough resolution to reveal the smallest details of interest. 
         [0005]    For example, the general Orthopantomogram (also referred to as OPG, panorex, or pano) employs a rotation technique where the center of rotation is moved during the image acquisition in order to reveal the upper and lower jaws (including teeth, bone structure beneath the teeth and the temporomandibular joint (TMJ)) on the produced two-dimensional view. In addition, the cephalometric imaging attachment employs combination of linear and rotation movement, but in order to show a projection, as parallel as possible, of the whole skull. 
         [0006]    The first Orthopantomogram device was developed in 1951, and the first manufacturing of such devices was begun in 1964 by Instrumentarium. Since than, companies such as Planmeca, Carestream Health (formerly Kodak), Gendex, Instrumentarium Dental, Sirona, Sorodex, and others manufacture various devices for panoramic and cephalometric radiation imaging. Many extraoral radiation devices, such as the Planmeca ProOne™, Kodak 8000, Gendex Orthoralix™ 8500 DDE, and the Sirona Orthophos™ 3 DS, do not have cephalometric capabilities. Others, such as the Kodak 9000C, provide cephalometric capabilities, but do not have a transferable sensor. 
         [0007]    Many dental and surgical offices require both types of imaging systems, and offices requiring both types of imaging systems had been required to purchase both systems. The radiation sensors for panoramic and cephalometric imaging systems are very costly components, and thus greatly increase the overall cost of the systems. A sensor which is transferable between a panoramic and cephalometric system would thus provide a very advantageous cost savings to a user of both systems. A third group of devices, such as Planmeca ProMax™, Gendex Orthoralix™ 9200 AEC, Instrumentarium Dental Orthoceph™ OC200 D, and Sirona Orthophos™ XG, do have cephalometric capabilities and a transferable sensor. Those systems, however, employ connection systems that are complicated, less reliable, and/or expensive. 
         [0008]    Further, most of the commonly used connectors in those systems have limited durability, on the order of 500 insertions. A very few connectors could reach 10,000 insertions. This durability sometimes is not enough for the long term usage of certain extraoral X-Ray devices, especially because of the usual long lifespan of more than ten years. Thus, most of the sensors on the market employ custom connectors with spring-loaded contacts to provide the needed maximum durability and reliability, as well as low resistance and capacitance for high-speed data transfer. That choice, however, adds cost to the sensor, and limits the sensor connector only to the essential data signals and power lines. 
         [0009]    The present invention relates to improvements to the apparatus described above and to solutions to some of the problems raised or not solved thereby. 
       SUMMARY OF THE INVENTION 
       [0010]    A need exists, therefore, for a radiation imaging system which has a sensor that is easily movable between a panoramic dental radiation imaging application and a cephalometric dental radiation imaging application and can be firmly secured in place in both applications. Objects of such a connector/attachment system include providing a low resistance and capacitance connection for high-speed data transfer, and high current capabilities for the power supply; the ability to be durable and reliable; the ability to provide precise and secure sensor attachment that does not introduce image distortion as result of mechanical movement; the ability to allow easy sensor attachment and detachment; the ability to provide meaningful sensor position detection; and the ability to provide additional manufacturing/diagnostic functionality, such as testing and programming interfaces. Further, the novel approach provided by the present invention also uses a high quality, high-speed connector, such as an MDR connector, although the solution is not limited only to this type of connector, with a stated durability of 10,000 insertions or more. That is enough for the most common usages of the sensor. As a further enhancement, the present invention also provides easy in-the-field replacement of the connector, if the sensor connector does happen to wear out. This approach decreases the overall cost and allows adding manufacturing/diagnostic capabilities to the sensor connector. 
         [0011]    The present invention relates to panoramic and cephalometric dental radiation imaging, and in particular to a radiation sensor which is movable between both types of systems, the sensor being easily removable from and connectable to each system, and firmly secured in place in each system. The invention provides a removable radiation sensor for being removably connected to a panoramic dental radiation imaging system, having a radiation source supported by an upright support. The removable radiation sensor includes a sensor housing and a radiation sensor unit mounted within the housing. Connector bearings are mounted within the housing and sized and positioned therein so as to engage with a pair of connector pins provided for that purpose as part of the upright support. A lock is mounted within the housing and selectively slidable between a locked position and an unlocked position. The lock includes a locking pin positioned within the housing transverse to the connector bearings, and therefore also transverse to the connector pins when the sensor is mounted to the upright support. The locking pin has a groove formed about the periphery of one end thereof, so that when the groove is aligned with one of the connector pins, that connector pin is slidable axially within the bearings, and the locking pin is thus in the unlocked position. When the groove is not aligned with the connector pin, the locking pin engages with a groove formed for that purpose in the connector pin, and the locking pin is therefore in the locked position, preventing the connector pin from sliding axially. A biasing spring is provided for biasing the locking pin toward the locked position. 
         [0012]    Other objects and advantages of the invention will become apparent hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a panoramic dental radiation imaging machine in accordance with one embodiment of the present invention; 
           [0014]      FIG. 2  is a perspective view of a C-arm portion of a panoramic dental radiation imaging machine; 
           [0015]      FIG. 3  is a perspective view of a dental radiation imaging machine with attachments for a removable sensor in a panoramic application and in a cephalometric application; 
           [0016]      FIG. 4  is rear perspective view of a removable sensor detached from a C-arm portion of a panoramic dental radiation imaging machine; 
           [0017]      FIG. 5  is a perspective view of a C-arm portion of a panoramic dental radiation imaging machine with a removable sensor detached from the C-arm; 
           [0018]      FIG. 6A  is a perspective view of a C-arm portion of a panoramic dental radiation imaging machine, with covers and certain parts removed to show detail as to how the removable sensor is attached to the C-arm portion of the panoramic dental radiation machine; 
           [0019]      FIG. 6B  is an end elevation view of the portion and parts shown in  FIG. 6A ; 
           [0020]      FIG. 7A  is a detail view of a locking pin and a bottom connector pin with sensor secured to C-arm and locking pin and button in default position; and 
           [0021]      FIG. 7B  is a detail view of a locking pin and bottom connector pin with button depressed and locking pin in position for detachment of sensor from C-arm. 
           [0022]      FIG. 8A  is a cross-section along line  8 A- 8 A in  FIG. 2  with a removable sensor attached to a C-arm and showing a locking pin in position for release of bottom connector pin and detachment of removable sensor; 
           [0023]      FIG. 8B  is a view similar to  FIG. 8A  with the removable sensor detached from the C-arm; 
           [0024]      FIG. 8C  is a perspective view of the C-arm portion and removable sensor of a panoramic dental radiation imaging machine similar to  8 B, enlarged and partially exploded to show detail. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    This application is being filed at the same time as a patent application on a patient positioning system for a panoramic dental radiation imaging system, and a patent application on a motion system for a dental imaging system, and a design patent application on a dental imaging system, all filed on the same day as this application and assigned to the same assignee. The disclosure of each of those other patent applications is incorporated herein by reference. 
         [0026]    One embodiment of a panoramic dental radiation imaging system  10  with a removable radiation sensor body  70 , having a radiation sensor unit  71  inside, is shown in  FIG. 1 . While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, certain illustrative embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to those as illustrated and described herein. Additionally, features illustrated and described with respect to one embodiment could be used in connection with other embodiments. 
         [0027]      FIGS. 1 and 2  show a panoramic dental radiation imaging system  10 . The imaging system  10  is used for imaging of a dental patient&#39;s teeth, and generally includes an upright support  15  for supporting a radiation source  65  and a radiation sensor  71  positioned inside a removable radiation sensor body  70 . In the most preferred embodiment shown, upright support  15  is formed of an outer column  20 , an inner column  30  capable of telescoping within the outer column, an overhead arm  40  rotatably fixed atop the inner column, a C-arm  60  rotatably connected to the distal end of the overhead arm, and a patient positioning arm  50  mounted to the inner column. Upright support  15 , by means of outer column  20 , may be fixed to a floor and/or a wall by a floor support foot  21  and/or a wall support leg  22  to support the radiation system  10 . As shown in the figures, according to the present invention, the radiation sensor body  70  is removable from and re-connectable to upright support  15 , in this embodiment by means of being removably connected to the C-arm  60 . 
         [0028]    In a preferred embodiment, sensor body  70  is comprised of a handle  72  and a housing  74 . Handle  72  allows a user to easily and firmly grasp sensor body  70  for removal from and attachment to radiation systems. A connection system, including a physical connection sub-system and an electrical connection sub-system, couples sensor body  70  to mounting portion  62  of C-arm  60 . As to the physical connection system, sensor body  70  is locked in place on C-arm  60  by means of a locking mechanism, in which mounting portion  62  of C-arm  60  has a top connector pin  64  and bottom connector pin  66  coupled thereto. Bottom connector pin  66  includes a neck  67  which allows sensor body  70  to be removably locked to, and removed from, C-arm  60 . 
         [0029]    As seen in  FIGS. 5 ,  6 A and  6 B, in the most preferred embodiment as shown, mounting plate  82  is coupled to sensor housing  74 , and openings  82 A,  82 B in mounting plate  82  receive top connector pin  64  and bottom  66  connector pin of C-arm  60 . An additional void in mounting plate  82  is provided through which an electronic connector  81  passes for connection to matching connector  68  of C-arm  60 , as will be explained in more detail below. Top connector bearings  84 A,  84 B coupled to sensor housing  74  receive top connector pin  64  when sensor body  70  is attached to C-arm  60 . Similarly, bottom connector bearings  86 A,  86 B receive bottom connector pin  66 . Top connector bearings  84 A,  84 B and bottom connector bearings  86 A,  86 B ensure proper alignment of top connector pin  64  and bottom connector pin  66  in the sensor housing  74 , as well as stabilize the pins  64 ,  66  when sensor body  70  is attached to C-arm  60 . 
         [0030]    The locking mechanism includes a locking pin  90  as shown in  FIGS. 6A ,  6 B,  7 A and  7 B which engages with bottom connector pin  66  at neck  67 . This engagement holds sensor body  70  securely in place on C-arm  60 , and also ensures that sensor body  70  is properly positioned on C-arm  60 , i.e. ensures that the sensor body  70  is not pushed too far onto connector pins  64 ,  66 , and that electronic connector  81  is not pushed too far into or onto matching connector  68 . To release the sensor body  70  from the C-arm  60 , a user pushes a button  96  on sensor housing  74 . Button  96  is coupled to locking pin  90 , which is spring-loaded against an opening  75  provided for that purpose in opposing side of housing  74  by any suitable biasing mechanism, such as a biasing spring  98 , shown in the embodiment of the figures as a coil spring. Thus, when button  96  is pushed against the force of spring  98 , the button and locking pin  90  then move in direction D 1  shown in  FIG. 7A  until a groove  92  formed for that purpose in the locking pin is aligned with bottom connector pin  66 , as shown in  FIGS. 6A and 7B . Groove  92  allows bottom connector pin  66  to disengage from locking pin  90 , allowing sensor body  70  to be pulled away from C-arm  60  and detached from the C-arm as shown in  FIG. 5 . When button  96  is released, the biasing force of spring  98  moves the button and the locking pin  90  back to the extended position ( FIG. 7A ) such that the spring  98  is extended. To re-attach sensor body  70 , connector pins  63  and  66  are inserted into openings  82 A,  82 B in mounting plate  82 , the button  96  is pushed, the groove  92  is again aligned with the connector pin  66 , the sensor body is slid the rest of the way onto the connector pins  64 ,  66 , the neck  67  of the bottom connector pin  66  is aligned with the locking pin  90 , and the button is released. This action locks the locking pin  90  onto the connector pin  66 , and thereby the sensor body  70  onto the C-arm  60 . 
         [0031]    As mentioned above, the radiation system  10  includes a primary electrical connection system  80 , which includes an electronic connector  81  positioned on sensor body  70 , and a matching electronic connector  68  for engaging with electronic connector  81 . Matching connector  68  is mounted to mounting portion  62 , between top connector pin  64  and bottom connector pin  66 . Thus when sensor body  70  is attached to C-arm  60 , the two parts of primary electrical connection  80 , which are electronic connector  81  and matching electronic connector  68 , are connected together. In the embodiment shown, particularly in  FIG. 8B , primary electrical connection system  80  is formed by the two parts of an MDR connector, but many other types of connectors are also possible and available, including but not limited to card edge connectors and pin-type connectors. The primary electrical connection system  80  provides the power and signal connections to the radiation sensor  71  inside the sensor body  70 . A corresponding mounting portion of a combination cephalometric/panoramic radiation system  110 , shown in  FIG. 3 , would be used to connect sensor body  70  to the cephalometric arm  160  of the combination system, such that the sensor body is easily movable from the C-arm  60 , that is, in use as a panoramic radiation system, to the cephalometric arm  160 , and back. 
         [0032]    In all known sensor systems, the sensor body  70  contains a very expensive radiation sensor  71 , which is very sensitive to electrostatic discharge (ESD). It is preferable therefore that the case be factory-sealed as it is required for repair personnel to take special care in handling the internal electronics. Thus, for nearly every repair, the entire sensor body  70 , containing the sensor unit  71 , is required to be returned back to the factory, adding cost and down time. Assuming the sensor body  70  is removed from the C-arm  60  repeatedly, the part most subject to wear and failure is the primary electrical connection system  80 . Adding the feature of field-replacement of the primary electrical connection system  80 , combined with low-level diagnostic capabilities as to the sensor unit  71  without opening the case, provides substantial advantages for field diagnosis and repair, decreasing overall cost and minimizing down time. The present invention provides an electrical connection system that can be replaced without opening the sensor body  70 , that is, a field-replaceable electrical connection system. 
         [0033]    To further facilitate disconnection and re-connection of the sensor unit  71  with the C-Arm  60 , referring mostly to  FIG. 8B , the matching electronic connector  68  is physically mounted to mounting portion  62  by means of a flexible or slightly movable connection, so that if electronic connector  81  and matching electronic connector  68  are misaligned by a small amount, they can still be engaged. There are a number of ways to advantageously accomplish this flexible connection. In the most preferred embodiment, matching connector  68  is physically connected to a printed circuit board  93 . Printed circuit board  93  is mounted to mounting portion  62  by threaded fasteners  94  passing through openings in the printed circuit board. O-rings  95  are provided to cushion the mounting of the threaded fasteners  94 , and thereby printed circuit board  93  and matching connector  68 , to mounting portion  62 . Thus, because of the O-rings  95 , matching connector  68  has some flexibility, in connecting to electronic connector  81 . 
         [0034]    In the most preferred embodiment, the field-replaceable electrical connection system includes a secondary electrical connection system  102 , besides the primary electrical connection system  80 . As shown best in  FIGS. 8A ,  8 B and  8 C, secondary electrical connection system  102  includes a second electronic connector  104  connected to electronic connector  81 , and a second matching connector  106 , which is in turn connected, by means of suitable circuit board  108 , to the sensor unit  71  ( FIG. 5 ) located within the sensor body  70 . The preferred embodiment of the secondary electrical connection system  102  is that of a card edge connector, but many other types of connectors are also possible and available, including but not limited to MDR connectors and pin-type connectors. With this system, when the electronic connector  81  wears out, it may be easily replaced, as shown in  FIG. 8C , by removal of a few screws and replacement of a small module  109  holding the electronic connector  81  and the second electronic connector  104 , and replacement with a new module  109 , without the risk or expense of opening the sensor body  70 . The number of times the secondary electrical connection system  102  is opened and closed will be much less than the number of times the electronic connector  81  and the matching connector  68  are engaged and disengaged, and so the secondary electrical connection system  102  will have more than a sufficient lifetime to last the life of the overall system  10 . Further, the use of an inexpensive and replaceable connection system permits the connector to have more lines of connection, allowing some such lines to be used for diagnostic and testing purposes, both in manufacturing and in the field. 
         [0035]    While the current implementation of the primary electrical connection system  80  uses a particular MDR male-female connector pair as it is currently described, the connector gender selection is not limited to the chosen one. Instead, other choices could be used, including reversed pair female-male, or hermaphroditic type of connectors such as the Samtec LST/HLST series of connectors. 
         [0036]    As indicated above, radiation sensor unit  71  is located within sensor housing  74 . Any suitable radiation sensor unit may be used in this application. In the embodiment shown, the most preferred radiation sensor unit is a CCD sensor with a CCD driver, an analog-front end, a programmable control and processing unit, and programming and diagnostic interfaces, besides a power supply. Other possible sensor implementations may not include all of the mentioned functions, or may add functions such as image processing, storage and other similar functions. Also, it is possible to use sensors other than CCD-type sensors, including CMOS sensors, which eventually may modify the implementation of the sensor driver functions and the analog-front end, or may require additional processing units. 
         [0037]    In an alternative embodiment (not shown), connector bearings  84 A,  84 B,  86 A,  86 B, electronic connector  81 , and locking pin  90  may be mounted within the C-arm  60  for receiving a pair of connector pins  66 ,  67  coupled to the sensor housing  74 . The connection and detachment of the sensor body  70  in this configuration would function in an identical fashion, with the mechanism for releasing the locking pin  90  located on the C-arm  60  rather than the sensor body  70 . 
         [0038]    Recently three dimensional imaging techniques have been introduced as well, and the current implementation could be extended to those techniques also. 
         [0039]    Although the invention has been herein described in what is perceived to be the most practical and preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Rather, it is recognized that modifications may be made by one of skill in the art of the invention without departing from the spirit or intent of the invention and, therefore, the invention is to be taken as including all reasonable equivalents to the subject matter of the appended claims and the description of the invention herein.