Patent Publication Number: US-2023157649-A1

Title: Multi-Directional X-Ray Imaging System

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The subject application is a continuation of U.S. application Ser. No. 17/201,416, filed on Mar. 15, 2021, which is a continuation of U.S. application Ser. No. 15/972,964, filed on May 7, 2018, which is a continuation-in-part of U.S. application Ser. No. 15/359,997, filed on Nov. 23, 2016, which is a continuation-in-part of U.S. application Ser. No. 13/916,869, filed on Jun. 13, 2013, which claims the benefit of priority to U.S. Provisional Application No. 61/659,609 filed on Jun. 14, 2012, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Conventional medical imaging devices, such as computed tomography (CT) and magnetic resonance (MR) imaging devices, are typically large, fixed bore devices. The patient must enter the device from the front or rear of the device in a lying position. These devices are limited in the types of imaging operations that may be performed. 
     SUMMARY 
     Embodiments include an imaging system having a gantry defining a central imaging bore and an imaging axis extending through the bore, the gantry comprising at least one imaging component for obtaining images of an object located within the bore, and at least one support member that supports the gantry such that the imaging axis has a generally vertical orientation, where the gantry is displaceable with respect to the at least one support member in a generally vertical direction. 
     In various embodiments, the gantry comprises a generally O-shaped housing having an internal cavity, and the imaging component(s), such as an x-ray source and/or x-ray detector, are rotatable around the gantry within the internal cavity. The imaging system may be configured to obtain a vertical imaging scan, such as a helical x-ray CT scan, of a patient in a weight bearing standing position. 
     In various embodiments, the gantry of the imaging system is rotatable with respect to the at least one support member between a first position, in which the gantry is supported such that the imaging axis has a generally vertical orientation, and a second position, in which the gantry is supported such that the imaging axis has a generally horizontal orientation. The gantry and the at least one support member may be displaceable in a generally horizontal direction relative to an object positioned within the bore. The system may thus perform a horizontal scan of a patient or object positioned within the bore. 
     In various embodiments, the gantry may be rotatable with respect to the at least one support member to a desired angle with respect to a tilted axis (i.e., an axis that is neither horizontal nor vertical). The gantry may be displaced both vertically and horizontally to perform an imaging scan along the titled axis. The angle of the gantry with respect to the tilted axis may remain fixed during the scan. 
     In further embodiments, a method of imaging an object includes positioning an object within a central imaging bore of a gantry comprising at least one imaging component for obtaining images of the object, the gantry having an imaging axis extending through the bore in a generally vertical orientation, displacing the gantry in a generally vertical direction with respect to the object, and obtaining image data of the object using the at least one imaging component. 
     In various embodiments, the method may further include rotating the gantry from a generally vertical orientation to a generally horizontal orientation, and displacing the gantry in a relatively horizontal direction relative to the object to perform an imaging scan. In various embodiments, the method may further include rotating the gantry to an angle with respect to a tilted axis, and displacing the gantry in both horizontal and vertical directions to perform an imaging scan along the tilted axis. 
     Further embodiments include an imaging system including a gantry having at least one imaging component for obtaining images of an object positioned within a bore of the gantry, the gantry having an imaging axis extending through the bore, the imaging system further including means for tilting the gantry to change an orientation of the imaging axis, means for displacing the gantry in a generally vertical direction with respect to the object, and means for obtaining image data of the object using the at least one imaging component. The imaging system may further include means for displacing the gantry in a generally horizontal direction with respect to the object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will be apparent from the following detailed description of the invention, taken in conjunction with the accompanying drawings of which: 
         FIG.  1 A  is a perspective view of an X-ray CT imaging system with a vertically displaceable gantry ring in accordance with one embodiment of the invention. 
         FIG.  1 B  illustrates the imaging system of  FIG.  1 A  with the gantry ring in a raised position. 
         FIG.  2    illustrates an embodiment imaging system imaging a patient in a weight-bearing standing position. 
         FIG.  3 A  illustrates an embodiment imaging system in which the gantry has been pivoted from a vertical orientation to a horizontal orientation, with the gantry horizontally displaced from a table column and support table. 
         FIG.  3 B  illustrates the imaging system of  FIG.  3 A  with the gantry translated in a horizontal direction (along z-axis) towards the table column and support table. 
         FIG.  3 C  illustrates the imaging system of  FIG.  3 A  further translated in a horizontal direction (along z-axis) towards the table column and support table. 
         FIG.  4    illustrates the support table rotated 90 degrees on the table column. 
         FIG.  5 A- 5 C  illustrate an embodiment imaging system performing an imaging scan along a tilted axis. 
         FIG.  6    illustrates a plurality of components housed within the gantry according to one embodiment. 
         FIG.  7 A  is an exploded view of a gantry illustrating an outer shell, a rotor and a bearing system according to one embodiment. 
         FIG.  7 B  is a perspective view of the assembled gantry. 
         FIG.  7 C  schematically illustrates the assembly of the gantry according to one embodiment. 
         FIGS.  8 A- 8 C  illustrate an embodiment x-ray CT imaging system performing a scan of a patient in a vertical direction. 
         FIGS.  9 A- 9 C  illustrate an embodiment x-ray CT imaging system performing a scan of a patient in a horizontal direction. 
         FIGS.  10 A- 10 C  illustrate an x-ray CT imaging system performing a scan of a patient along a tilted axis. 
         FIGS.  11 A- 11 C  illustrate an x-ray CT imaging system having an imaging gantry supported by a pair of support columns and a cavity in a base of the imaging system configured to receive the gantry. 
         FIGS.  12 A- 12 D  illustrate an x-ray CT imaging system having an imaging gantry supported by a support column and a cavity in the floor configured to receive the gantry. 
     
    
    
     DETAILED DESCRIPTION 
     This application is related to U.S. application Ser. No. 12/576,681, filed Oct. 9, 2009, now U.S. Pat. No. 8,118,488, U.S. application Ser. No. 13/025,566, filed Feb. 11, 2011, U.S. application Ser. No. 13/025,573, filed Feb. 11, 2011, U.S. application Ser. No. 13/441,555, filed Apr. 6, 2012, and U.S. Provisional Application No. 61/658,650, filed Jun. 12, 2012. The entire contents of all of these applications are hereby incorporated by reference for all purposes. The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the invention or the claims. 
     Referring to  FIG.  1 A , an imaging system  100  according to one embodiment of the invention is shown. The system  100  includes image collection components, such as a rotatable x-ray source and detector array or stationary magnetic resonance imaging components, that are housed within the gantry  40 . The system  100  is configured to collect imaging data, such as, for example x-ray computed tomography (CT) or magnetic resonance imaging (MRI) data, from an object located within the bore  116  of the gantry  40 , in any manner known in the medical imaging field. 
     The system  100  may include a base  102 , which may be a stable, high-strength support structure having a generally flat top surface. The base  102  may be supported on a suitable weight-bearing surface, such as on the ground or on a floor of a building. At least one support column  31 ,  33  may extend in a generally vertical direction from the base  102 , and the gantry  40  may be attached to and supported above the base  102  by the at least one support column  31 ,  33 . In the embodiment shown in  FIG.  1 A , two support columns  31 ,  33  (e.g., support posts or rails) are supported by the base  102  and extend in a generally vertical direction from the top surface of the base  102 . The support columns  31 ,  33  are each attached to opposite sides of the gantry  40 . The support columns  31 ,  33  may be attached to opposite sides of the gantry by attachment mechanisms  201 ,  203 , as described in further detail below. It will be understood that more than two support columns (e.g., 3 or more), or a single support column may support the gantry above the base  102  in various embodiments. Also, in various embodiments, the base  102  may be omitted, and the at least one support column  31 ,  33  may be directly supported on the ground or floor. 
     In further embodiments, the at least one support column  31 ,  33  may be supported by a ceiling, a wall or other support structure, and may be hung or cantilevered from the support structure in a generally vertical orientation. 
     In various embodiments, the system  100  may be a fixed room (e.g., not mobile) imaging system. Alternatively, the system may be a mobile system that includes suitable means for transporting the entire system  100  (e.g., a drive mechanism coupled to one or more wheels, casters, rollers, etc.). The system  100  may further include a table column  50  for supporting one or more support tables, as described in further detail below. 
     As shown in  FIG.  1 A , the gantry  40  comprises a generally O-shaped structure having a central imaging bore  116 . The bore  116  defines a central imaging axis  114 . In various embodiments, the at least one support column  31 ,  33  may support the gantry  40  such that the imaging axis  114  has a generally vertical orientation. By generally vertical orientation, the imaging axis  114  may be normal to the flat top surface of base  102  or other planar horizontal surface on which the system  100  is supported (e.g., the ground or floor), and includes deviations up to 45° from the normal orientation (e.g., the imaging axis  114  is oriented at no more than 45° relative to the horizontal top surface of base  102 ). 
     The gantry  40  may be displaceable relative to at least one support column  31 ,  33 . In embodiments, the gantry  40  may be displaceable along at least one dimension of the at least one support column  31 ,  33 , such as along a length of the at least one support column  31 ,  33 . In embodiments, the at least one support column  31 ,  33  may have a generally vertical orientation, and the gantry  40  may be displaceable in a generally vertical direction, such as the direction indicated by arrow  112  in  FIG.  1 A . By generally vertical orientation, the direction of displacement  112  may be normal to the flat top surface of base  102  or other planar horizontal surface on which the system  100  is supported (e.g., the ground or floor), and includes deviations up to 45° from the normal orientation (e.g., the direction of gantry displacement  112  is oriented at an angle more than 45° relative to the horizontal top surface of base  102 ). 
     The gantry  40  and the at least one support column  31 ,  33  may include mating features that enable the displacement of the gantry  40  relative to the support column(s)  31 ,  33  in a generally vertical direction  112 , while the gantry  40  is restricted from moving in other directions relative to the support column(s)  31 ,  33 . In the embodiment of  FIG.  1 A , the support column  31 ,  33  may each include rail(s)  118  extending along the length of the support column  31 ,  33 . The gantry  40 , or in the embodiment shown in  FIG.  1 A , the attachment mechanisms  201 ,  203 , may include features that mate with the respective rails  118  to enable the displacement of the gantry  40 . A first drive mechanism may drive the displacement (movement) of the gantry  40  relative to the support member(s)  31 ,  33 . The first drive mechanism may comprise, for example, a traction drive, a gear system, a belt drive, a pulley, a drivewheel, etc., or various combinations thereof. The first drive mechanism may be mechanically coupled to and driven by one or more motor(s), which may be located on the gantry  40  and/or on one or more support columns  31 ,  33 . A controller may control the operation of the motorized drive mechanism and thereby control the displacement of the gantry  40 . The controller may receive position feedback signals indicative of the relative position of the gantry  40  and the one or more support columns  31 ,  33 , such as from a linear encoder. 
     In embodiments, the gantry  40  may be vertically displaced along substantially the entire length of the support columns  31 ,  33 .  FIG.  1 B  illustrates the system of  FIG.  1 A  with the gantry  40  displaced along the direction of arrow  112  to a height above the base  102  and floor. In embodiments, the gantry  40  may be displaceable from a first position proximate to the base  102  and floor of a room to a second position proximate the ceiling of the room. In some embodiments, the gantry  40  may be further displaceable into the ceiling, such as into a cavity or enclosure formed in the ceiling. Alternatively, or in addition, the gantry  40  may be displaceable into the base  102  and/or floor, such as in a cavity or enclosure formed in the base  102  and/or the floor. The respective cavities or enclosures may include doors or panels that can be closed to fully house the gantry within the cavity or enclosure. In this way, the gantry  40  may be moved completely out of the way and safely stored when not in use. The support columns  31 ,  33  may also be retracted into the floor and/or ceiling, such as in a telescoping fashion, or otherwise removed, when the system is not in use. 
     The imaging components of the gantry  40  may obtain imaging data of an object positioned within the bore  116  while the gantry  40  is displaced in a generally vertical direction to obtain a vertical scan of the object. For an x-ray CT imaging system, for example, an x-ray source and detector may rotate within the gantry  40  while the gantry is vertically displaced to provide a helical scan in a generally vertical orientation. In various embodiments, the system  100  may perform a helical scan of a human or animal patient in a weight bearing standing position. 
     Various examples of diagnostic imaging applications that may be performed on a human or animal patient in a weight-bearing position using the present system include, without limitation:
         Imaging the bones of a foot. The three-dimensional relationships of the bones in the foot in a flatfoot deformity are difficult to assess with standard radiographs. CT scans demonstrate these relationships but are typically made in a non-weightbearing mode. The use of a weightbearing CT or other imaging apparatus may be useful in imaging the feet in patients with severe flexible pesplanus deformities and to better define the anatomical changes that occur.   Imaging of a limb (e.g. leg). Weight-bearing (CT) bilateral long leg hip to ankle examination and non-weight bearing cross-sectional imaging (CT) of the affected limb may be performed on the hip, knee and ankle, for example, and may be useful for determining variations in angulation and alignment accuracy for diagnosis and/or surgical planning.   Imaging of a spine. Weight bearing scanning (e.g., CT scanning) may be useful for improvements in the accurate diagnosis of degenerative spinal disorders by scanning a patient in the “real life” standing position. By scanning in the standing position, the spinal disc and facet joint compresses, which may enable more specific and precise diagnosis of degenerative spine disorders.   Imaging of a joint (e.g., knee). Weight bearing scanning (e.g., CT scanning) of the knee may enable more specific and precise diagnosis of the patella-femoral kinematics and may also be useful in surgical planning.   Angiography. Weight bearing angiography (e.g., CT angiography) may enable more accurate diagnosis, and may be used, for example, to examine the pulmonary arteries in the lungs to rule out pulmonary embolism, a serious but treatable condition. Weight bearing angiography may also be used to visualize blood flow in the renal arteries (those supplying the kidneys) in patients with high blood pressure and those suspected of having kidney disorders. Narrowing (stenosis) of a renal artery is a cause of high blood pressure (hypertension) in some patients and can be corrected. A special computerized method of viewing the images makes renal CT angiography a very accurate examination. This is also done in prospective kidney donors. Weight bearing angiography may also be used to identify aneurysms in the aorta or in other major blood vessels. Aneurysms are diseased areas of a weakened blood vessel wall that bulges out—like a bulge in a tire. Aneurysms are life-threatening because they can rupture. Weight bearing angiography may also be used to identify dissection in the aorta or its major branches. Dissection means that the layers of the artery wall peel away from each other—like the layers of an onion. Dissection can cause pain and can be life-threatening. Weight bearing angiography may also be used to identify a small aneurysm or arteriovenous malformation inside the brain that can be life-threatening. Weight bearing angiography may also be used to detect atherosclerotic disease that has narrowed the arteries to the legs.       

       FIG.  2   , for example, illustrates a patient  105  in a standing position within an embodiment imaging system  100 . The patient  105  is standing on the base  102  within the bore  116  of the gantry  40 . The system  100  may be used to perform an imaging scan of the patient  105  in a generally vertical direction, as indicated by arrow  112 . In embodiments, the system  100  may scan any portion of the patient&#39;s anatomy, including a full-body scan. The system  100  may also be used to perform a vertical scan of a patient in a sitting position or a reclined position. 
     In embodiments, the system  100  may include at least one patient/object support structure  202  that may extend from the base  102  in a generally vertical direction. The support structure  202  may be aligned with the bore  116 . The support structure  202  may be made of a radiolucent (x-ray transparent) material. As shown in  FIG.  2   , a support structure  202  may be radiolucent (x-ray transparent) vertical rigid post or plate that the patient  105  may grab or sit on to help stabilize the patient throughout the scan. The support structure  202  may have handles or arm rests at varying heights to help the patient lean against and stay motionless during the scan. The support structure  202  may also be a post with a radiolucent chair for people who have a hard time standing during a scan, or it may be two plates that sandwich the patient in a vertical standing position to help the patient remain still during a scan. 
     The support structure  202  may be made entirely or partially of any radiolucent material such as carbon fiber, etc. 
     In embodiments, the gantry  40  may be attached to the at least one support column  31 ,  33  such that the gantry  40  may pivot or tilt with respect to the support column(s)  31 ,  33 . As shown in  FIG.  1 A , for example, the gantry  40  may be attached to the support columns  31 ,  33  by respective attachment mechanisms  201 ,  203 . The attachment mechanisms  201 ,  203  may include a bearing assembly that allows the gantry  40  to pivot with respect to the support columns  31 ,  33 . In an alternative embodiment, the gantry  40  may be directly attached to the support columns  31 ,  33  (e.g., without a separate attachment mechanism  201 ,  203  as shown in  FIG.  1 A ) via a bearing assembly (not illustrated) that enables the gantry  40  to pivot with respect to the support columns. In embodiments, the gantry  40  may pivot at least about 45° relative to the support columns  31 ,  33 . In preferred embodiments, the gantry  40  may pivot more than 45°, such as at least about 90°, relative to the support columns  31 ,  33 . In some embodiments, the gantry  40  may pivot between a generally vertical orientation (such as shown in  FIGS.  1 A-B ) and a generally horizontal orientation, as shown in  FIGS.  3 A-C . By generally horizontal orientation, the imaging axis  114  may be parallel to the flat top surface of base  102  or other planar horizontal surface on which the system  100  is supported (e.g., the ground or floor), and includes deviations up to 45° from this parallel orientation (e.g., the imaging axis  114  is oriented less than 45° relative to the horizontal top surface of base  102 ). 
     In a generally horizontal configuration, the system  100  may perform an imaging scan of an object positioned on a suitable support, such as tabletop support  60 , shown in  FIGS.  3 A-C . The table column  50  may be configured to support the tabletop support  60 . The tabletop support  60  may be attached to the table column  50  in a cantilevered manner, such that at least a portion of the tabletop support  60  may extend over the base. A portion of the tabletop support  60  may extend into the bore  116  of the gantry  40 . The tabletop support  60  may include, for example, any suitable table, such as a patient table, as well as a chair for a seated patient. 
     An imaging scan may be performed via a relative displacement of the gantry  40  and the tabletop support  60 . The relative displacement may be in a generally horizontal direction, such as indicated by arrow  212 . The relative displacement may be the displacement of the tabletop support  60 , such as a displacement of the table column  50  and tabletop support  60  with respect to a stationary gantry  40 , or a displacement of the tabletop support  60  with respect to a stationary table column  50  and gantry  40 . In other embodiments, the gantry  40  may move relative to a stationary tabletop support  60 . In further embodiments, both the gantry  40  and the tabletop support  60  may move. 
     In the embodiment illustrated in  FIGS.  3 A- 3 C , the gantry  40  and the at least one support column  31 ,  33  may be displaced relative to the base  102 , table column  50  and patient table  60 , which may be stationary. The base  102  and the at least one support column  31 ,  33  may include mating features that enable the displacement of the support members  31 , 33  (along with the gantry  40  and attachment mechanisms  201 ,  203  to which they are attached), relative to base  102  in a generally horizontal direction  212 , while the support column(s)  31 ,  33  and gantry  40  are restricted from moving in other directions relative to base  102 . In the embodiment of  FIGS.  3 A-C , the base  102  may include a horizontal guide in the form of rails  110  extending along the length of the base  102 . The support columns  31 ,  33  may include features that mate with the respective rails  110  to enable the horizontal displacement of the support columns  31 ,  33  and gantry  40 . A second drive mechanism (e.g., z-drive) may drive the displacement (movement) of the support columns  31 ,  33 , attachment mechanisms  201 ,  203  and gantry  40  along the base  102 . The second drive mechanism may comprise, for example, a traction drive, a gear system, a belt drive, a pulley, a drivewheel, etc., or various combinations thereof. The second drive mechanism may be mechanically coupled to and driven by one or more motor(s), which may be located on the base  102  and/or on one or more support column(s)  31 ,  33 . A controller may control the operation of the motorized second drive mechanism and thereby control the displacement of the support columns  31 ,  33  and gantry  40 . The controller may receive position feedback signals indicative of the position of the support column(s)  31 ,  33  and gantry  40  relative to the base  102 , such as from a linear encoder. 
     The drive mechanism for vertical displacement as described above may be used to adjust the height of the gantry  40  relative to the tabletop support  60 , either before or during a horizontal scan. Similarly, the drive mechanism for horizontal displacement as described above may be used to adjust the position of the gantry  40  in a horizontal direction (e.g., z-direction), either before or during a vertical scan. 
       FIGS.  3 A-C  illustrate an embodiment of a system  100  performing a horizontal scan. In  FIG.  3 A , the gantry  40  and support columns  31 ,  33  are located away from the table column  50  and the distal end of the tabletop support  60  is within the bore  116 . In  FIG.  3 B , the gantry  40  and support columns  31 ,  33  are moved towards the table column  50  in the direction of arrow  212 , and the tabletop support  60  extends fully through the bore  116 . In  FIG.  3 C , the gantry  40  and support columns  31 ,  33  have traveled to the proximal end of rails  110 , and the gantry  40  is proximate to the table column  50 . The imaging components of the gantry  40  may obtain imaging data of an object positioned within the bore  116  while the gantry  40  is displaced in a generally horizontal direction, as shown in  FIGS.  3 A-C , to obtain a horizontal scan of the object. For an x-ray CT imaging system, for example, an x-ray source and detector may rotate within the gantry  40  while the gantry is horizontally displaced to provide a helical scan in a generally horizontal orientation. In various embodiments, the system  100  may perform a horizontal scan of a human or animal patient in a lying position. 
       FIG.  4    illustrates a system  100  according to one embodiment wherein the tabletop support  60  may be rotated at least about 90° on the table column  50 . In embodiments, the tabletop support  60  may be rotated to facilitate loading/unloading of a patient, or to provide better access to the patient for a medical procedure. The tabletop support  60  may be rotated back to the orientation of  FIGS.  3 A-C  in order to perform an additional imaging scan, without having to remove the patient or move the patient relative to the tabletop support  60  between scans. The tabletop support  60  may be rotated to the orientation of  FIG.  4    to perform a scan in a generally vertical orientation, such as shown in  FIGS.  1 A- 2   . In embodiments, the tabletop support  60  may also translate with respect to the table column  50  in one or more directions. The height of the table column  50  may also be adjustable. 
       FIGS.  5 A- 5 C  illustrate an embodiment imaging system  100  performing a scan along a tilted axis. In  FIG.  5 A , the object being imaged (e.g., patient  105 ) is positioned along a tilted axis  514  (i.e., neither horizontal nor vertical). The patient  105  may be supported against a support structure  60  that is similarly aligned along tilted axis  514 . The gantry  40  may be tilted on the support columns  31 ,  33  to any desired angle relative to axis  514 , and may be perpendicular to axis  514 . The region of interest of the patient  105  may be centered within the bore (e.g., such that the bore imaging axis is collinear with the tilted axis  514 ). In various embodiments, the imaging system  100  may perform an imaging scan (e.g., a helical x-ray CT scan) of the patient  105  while maintaining a fixed angle between the gantry and the tilted axis  514  and maintaining the region of interest centered within the bore. The imaging system  100  may achieve this via coordinated movement of the gantry in both a vertical direction (indicated by arrow  112 ) and a horizontal direction (indicated by arrow  212 ). The vertical movement of the gantry  40  may be with respect to the support column(s)  31 ,  33 , and may be along vertical rail(s)  118 , as described above. The horizontal movement of the gantry  40  may be the movement of the support column(s)  31 ,  33 , attachment mechanisms  201 ,  203  and gantry  40  along the base  102 , and may be along a horizontal guide (rail(s)  110 ), as described above. A control system of the imaging system  100  may include logic configured to determine the relative vertical and horizontal displacement of the gantry  40  needed to translate the gantry along a tilted axis  514 . First and second drive mechanism(s) for producing the respective vertical and horizontal movements of the gantry  40  may be controlled by the control system to provide coordinated vertical and horizontal displacement of the gantry. Where the angle of the tilted axis  514  is known or may be determined, the control system may use simple trigonometric relations to determine the vertical and horizontal displacement of gantry  40 . For example, where the tilted axis  514  is at a 60° angle relative to horizontal, each cm of the scan along axis  514  may include a vertical displacement of ˜0.87 cm (i.e., sin 60°) and a horizontal displacement of 0.5 cm (i.e., cos 60°). Thus, the imaging system  100  may perform a scan at any tilt axis  514 , and in embodiments may perform scans along complex axes, such as along an angled or curved axis. 
       FIGS.  5 A- 5 C  illustrate an example of an imaging scan of a patient along a tilted axis  514 . The patient  105  may lean against support  60  such that the patient is aligned along the tilted axis  514 . The gantry  40  may be tilted such that the gantry is perpendicular to tilted axis  514 , with the patient centered within the bore of the gantry. The gantry  40  may then be displaced in both vertical and horizontal directions such that the gantry  40  may translate along the length of the patient  105 , as shown in  FIGS.  5 B and  5 C . The gantry  40  may remain perpendicular to the tilted axis  514  through the duration of the scan. Imaging components, such as an x-ray source and detector, may rotate within the gantry  40  while the gantry translates along the length of the patient  105  to obtain a helical scan. 
     A number of imaging components that may be included in the imaging system  100  for providing an imaging scan are illustrated in  FIG.  6   . The components may be housed within the gantry  40 . In one embodiment, the imaging system  100  comprises an X-ray CT imaging system, and includes an x-ray source  43 , high-voltage generator  44 , heat exchanger  430 , x-ray detector  45 , power supply  63  (e.g., battery system), computer  46 , rotor drive mechanism  47 , and a docking system  35  (e.g., for providing intermittent power/data connection between rotating and non-rotation portions of the system). These components may be mounted on a rotor  41  to collectively define a rotating portion  101  of the system. The rotor  41  and the components mounted thereto may rotate around a housing defined by an outer shell  42  ( FIG.  7 A ) of the gantry  40  and within an internal cavity of the gantry  40 . 
     It will be understood that the components described and illustrated are merely exemplary, and other embodiments may omit one or more of these components and may utilize other additional components. For example, in embodiments, power for the rotating portion  101  may be provided by a slip ring or cable system, so that a power supply  63  on the rotating portion  101  may not be needed. In some embodiments, power and/or data may be continuously transferred between the rotating and non-rotating portions via cable, slip ring or wirelessly, in which case the power supply  63 , computer  46  and/or docking system  35  may not be included. Further, the rotation of the rotor may be provided by a drive system on the non-rotating portion, in which case the rotor drive mechanism  47  on the rotor  41  may not be included. Also, it will be understood that other types of imaging systems, such as MRI systems, may use other suitable components for imaging, as are known in the art. 
     In embodiments, the x-ray source  43  and detector  45  may be configured to perform a helical x-ray CT scan. The detector  45  may comprise a plurality of x-ray sensitive detector elements arranged in a semicircular arc, with the arc center coinciding with the focal spot of the x-ray source. In some embodiments, the x-ray detector may be a flat panel detector, and the system may be configured to perform real time x-ray and/or cone beam imaging of an object within the bore of the gantry. The system may be a single plane system (i.e., having a single source and detector which can obtain an image in a single plane at one time), or in some embodiments, may be a bi-plane or multi-plane system (i.e., having multiple x-ray source(s) and/or detector(s) at different positions on the ring for obtaining images in multiple planes at the same time). 
     In the embodiment of  FIG.  6   , during an imaging scan, the rotor  41  rotates within the interior of the gantry, while the imaging components such as the x-ray source  43  and x-ray detector  45  obtain imaging data for an object positioned within the bore  116  of the gantry, as is known, for example, in conventional X-ray CT scanners. The rotor drive mechanism  47  may drive the rotation of the rotor  41  around the interior of the gantry  40 . The rotor drive mechanism  47  may be controlled by a system controller that controls the rotation and precise angular position of the rotor  41  with respect to the gantry  40 , preferably using position feedback data, such as from a position encoder device. 
     Various embodiments of the imaging system  100  may be relatively compact. One way in which the system  100  may be made compact is in the design of the gantry  40  and its interface with the rotating portion  101  (e.g., the rotor  41  and the various components mounted to the rotor  41 ). In embodiments, the outer shell  42  of the gantry  40  may comprise both a protective outer covering for the rotating portion  101  and a mounting surface for a bearing that enables the rotating portion  101  to rotate 360° within the outer shell  42  of the gantry  40 . 
       FIG.  7 A  is an exploded view of a gantry  40  according to one embodiment that illustrates the outer shell  42 , the rotor  41  and a bearing assembly  400 .  FIG.  7 B  illustrates the assembled gantry  40 . As is shown in  FIGS.  7 A-B , the outer shell  42  of the gantry  40  may be a generally O-shaped covering of a structural material that may at least substantially fully enclose the rotating portion  101 , including the rotor  41  and any components mounted to the rotor, over one or more sides of the rotating portion  101 . The outer shell  42  of the gantry  40  may be conceptually considered an “exoskeleton,” that both supports the rotating portion  101  of the system  100 , preferably in three dimensions, and also provides a protective barrier between the rotating portion  101  and the external environment. The outer shell  42  may be fabricated from a sufficiently rigid and strong structural material, which may include, for example, metal, composite material, high-strength plastic, carbon fiber and combinations of such materials. In preferred embodiments, the outer shell  42  may be comprised of a metal, such as aluminum. The outer shell  42  may be machined or otherwise fabricated to relatively tight tolerances. The outer shell  42  may be formed as a one piece, unitary component. In other embodiments, the outer shell  42  may be comprised of multiple components and/or materials that may be joined using any suitable technique to provide the shell  42 . 
     The outer shell  42  may have an outer circumferential surface  406  that may extend around the periphery of the rotating portion  101  of the system  100  to substantially fully enclose the rotating portion  101  around its outer circumference. The outer shell  42  may also include at least one side wall  412  that may extend from the outer circumferential surface  406  to a bore  116  of the gantry  40  and may substantially fully enclose the rotating portion  101  around one side of the rotating portion. 
     The bearing assembly  400  according to one embodiment is shown in  FIG.  7 A . In this embodiment, the bearing assembly  400  includes a first race  402  that may be securely fastened to the outer shell  42  of the gantry  40 , and a second race  404  that may be securely fastened to the rotor  41 . A bearing element is provided between the first race  402  and the second race  404 , and is configured to allow the second race  404  (along with the rotor  41  to which it is attached) to rotate concentrically within the first race  402 , preferably with minimal friction, thereby enabling the rotor  41  to rotate with respect to the outer shell  42  of the gantry  40 . In some embodiments, all or a portion of the bearing assembly  400  may be integrally formed as a part of the outer shell  42 , of the rotor  41 , or of both. For example, the first race  402  may be formed as an integral surface of the outer shell  42  and/or the second race  404  may be formed as an integral surface of the rotor  41 . In various embodiments, the entire bearing assembly for enabling the rotation of the rotating portion  101  with respect to the non-rotating portion  103  of the imaging system  100  may be located within the generally O-shaped gantry  40 . 
     The outer diameter of the gantry  40  can be relatively small, which may facilitate the portability of the system  100 . In a preferred embodiment, the outer diameter of the gantry  40  is less than about 70 inches, such as between about 60 and 68 inches, and in one embodiment is about 66 inches. The outer circumferential wall  406  of the outer shell  42  may be relatively thin to minimize the OD dimension of the gantry  40 . In addition, the interior diameter of the gantry  40 , or equivalently the bore  116  diameter, can be sufficiently large to allow for the widest variety of imaging applications, including enabling different patient support tables to fit inside the bore, and to maximize access to a subject located inside the bore. In one embodiment, the bore diameter of the gantry  40  is greater than about 38 inches, such as between about 38 and 44 inches, and in some embodiments can be between about 40 and 50 inches. In one exemplary embodiment, the bore has a diameter of about 42 inches. The gantry  40  generally has a narrow profile, which may facilitate portability of the system  100 . In one embodiment, the width of the gantry  40  (W) is less than about 17 inches, and can be about 15 inches or less. 
       FIG.  7 C  illustrates the gantry  40  and attachment mechanisms  201 ,  203  for securing the gantry  40  to the support column(s)  31 ,  33  (see  FIG.  1 A ). The attachment mechanisms  201 ,  203 , which may have an “earmuff” shape, may include bearing apparatuses that enable the pivot motion of the gantry  40  relative to the support column(s)  31 ,  33 , such as a pivot motion from a vertical to a horizontal orientation, and vice versa. One or both of the attachment mechanism(s)  201 ,  203  may also include a portion of a docking system for providing power and data transfer between rotating and non-rotating portions of the system. The system  100  may be assembled by securing the attachment mechanisms  201 ,  203  to opposite sides of the gantry  40 . The entire assembly may then be attached to the support columns  31 ,  33 . 
       FIGS.  8 A- 8 C,  9 A- 9 C and  10 A- 10 C  illustrate yet another embodiment of an imaging system  800 . The imaging system  800  in this embodiment includes an imaging gantry  40  mounted to a support column  801 . The support column  801  may be mounted to the gantry  40  on a first side of the gantry  40  and may support the gantry  40  in a cantilevered manner. The gantry  40  may be a generally O-shaped structure having a central imaging bore  116  and defining an imaging axis  114  extending through the bore. The gantry  40  may contain one of more of the components described above with reference to  FIG.  6   , such as an x-ray source, a detector, a high-voltage generator, a heat exchanger, a power supply (e.g., battery system), and a computer. These components may be mounted on a rotating element (e.g., a rotor) that rotates within the gantry  40  during an imaging scan. A rotor drive mechanism may also be located on the rotor, and may drive the rotation of the rotor. Between scans, a docking system may be used to couple the rotating and non-rotating portions of the system  800  for power and data communication. 
     The system  800  may also include a base  802  that may be located on a weight-bearing surface, such as a floor  819  of a building. In the illustrated embodiment, the base  802  comprises a generally rectilinear support structure that may be mounted (e.g., bolted) to the floor  819 . The support column  801  may be located on and supported by the base  802  and may extend upwards from the top surface of the base  802  in a generally vertical direction. The support column  801  may have a length dimension that extends vertically at least about 2 meters, such as 2-5 meters (e.g., about 3 meters). 
     As shown in  FIGS.  8 A- 8 C , the support column  801  may support the gantry  40  in a generally vertical orientation, such that the front and rear faces of the gantry  40  extend parallel to the floor  819  and the imaging axis  114  through the gantry bore  116  extends in a vertical direction (i.e., perpendicular to the floor). The imaging axis  114  of the gantry  40  in this configuration may extend parallel to the length dimension of the vertically-extending support column  801 . 
     The gantry  40  may be displaced along the length of the support column  801  in a generally vertical direction. This is illustrated in  FIGS.  8 A- 8 C , which show the gantry  40  displaced vertically from a first position in  FIG.  8 A  with the gantry  40  located proximate a first end of the support column  801  (i.e., opposite the base  802 ), to a second position in  FIG.  8 B  with the gantry  40  located approximately mid-way along the length of the support column  801 , to a third position in  FIG.  8 C , with the gantry  40  located proximate to a second end of the support column  801  proximate to the base  802 . The gantry  40  and the support column  801  may include mating features that confine the displacement of the gantry  40  along the length of the support column  801 . As shown in  FIGS.  8 A- 8 C , for example, a pair of parallel vertical rails  805 ,  806  may extend in a vertical direction along the length of the support column  801 . An attachment mechanism  807  may be attached to one side of the gantry  40 , and may be located between the side of the gantry  40  and the support column  801 . The attachment mechanism  807  may include bearing elements (e.g., roller and/or dovetail bearing slides) that engage with the vertical rails  805 ,  806  to provide linear motion of the attachment mechanism  807  and gantry  40  along the length of the support column  801 . 
     A first drive mechanism may drive the displacement of the gantry  40  and attachment mechanism  807  relative to the support column  801 . A first drive mechanism  808  is schematically illustrated in  FIG.  10 A . The first drive mechanism  808  may comprise a linear actuator, such as a lead screw or ball screw system. In embodiments, a threaded shaft may extend lengthwise within an interior housing  809  of the support column  801 . A motor, which may also be located within the support column  801 , may be geared into the threaded shaft to drive the rotation of the shaft. An arm may extend from the attachment mechanism  807  through an opening  811  (e.g., a slot) extending along the length of the support column  801 . A nut on the end of the arm may engage with the threaded shaft within the housing  809  of the support column  801 . The rotation of the threaded shaft may cause the nut to reciprocate up and down along the length of the shaft. The reciprocation of the nut on the shaft may drive the vertical displacement of the attachment mechanism  807  and gantry  40  with respect to the support column  801 . A controller  810  (see  FIG.  10 A ) may control the operation of the first drive mechanism and thereby control the vertical displacement of the gantry  40 . The controller may receive position feedback signals indicative of the position of the gantry  40  along the support column  801 , such as from a linear encoder. 
     The system  800  may also include a patient support  813 . The patient support  813  may support a patient  105  in a weight-bearing standing position as shown in  FIGS.  8 A- 8 C . The patient support  813  may include a first portion  815  that supports the feet of a patient upon which the patient  105  may stand. A second portion  817  may extend generally perpendicular to the first portion  815  and may provide additional support to the patient  105 . For example, the patient  105  may lean against the second portion  817  during a scan and the second portion  817  may help to stabilize the patient  105  and prevent the patient  105  from falling off the patient support  813 . In embodiments, the patient support  813  may support the patient  105  in a position that is raised above the floor  819 , as shown in  FIGS.  8 A- 8 C . The first portion  815  and the second portion  817  may be made of a radiolucent (x-ray transparent) material, such as carbon fiber material. 
     The system  800  may be used to perform an imaging scan of a patient  105  in a weight-bearing standing position. For example, for an x-ray CT imaging system, the x-ray source and detector may rotate within the gantry  40  around the patient while the gantry  40  and attachment mechanism  807  are displaced vertically on the support column  801  as shown in  FIGS.  8 A- 8 C  to perform a helical scan of a patient  105  positioned on the patient support  813 . In embodiments, the system  800  may scan over the full length of the patient (e.g., from the top of the patient&#39;s cranium to the bottom of the patient&#39;s feet) or any selected portion thereof. Following a scan, the gantry  40  may be moved to an out-of-the way position (e.g., to the top of the support column  801  or below the patient&#39;s feet) and the patient  105  may be removed from the patient support  813 . 
     The gantry  40  may be attached to the support column  801  by the attachment mechanism  807  such that the gantry  40  may pivot (i.e., tilt) with respect to the support column  801 . This is illustrated in  FIGS.  9 A- 9 C , which illustrate the gantry  40  pivoted from a generally vertical orientation (as shown in  FIGS.  8 A- 8 C ) with the front and rear faces of the gantry  40  extending parallel to the floor  819  and the imaging axis  114  extending in a vertical direction (i.e., perpendicular to the floor) to a generally horizontal orientation with the front and rear faces of the gantry extending perpendicular to the floor  819  and the imaging axis  114  extending in a horizontal direction (i.e., parallel to the floor). The imaging axis  114  of the gantry  40  in the configuration shown in  FIGS.  9 A- 9 C  may extend perpendicular to the length dimension of the vertically-extending support column  801 . 
     In embodiments, the gantry  40  may be attached to the attachment mechanism  807  via a bearing assembly (i.e., a rotary bearing assembly) that allows the gantry  40  to pivot with respect to the support column  801 . In one embodiment, the rotary bearing assembly may include a first portion (i.e., bearing race) mounted to the attachment mechanism  807  and a second portion (i.e., bearing race) mounted to the gantry  40 . The two bearing portions may rotate concentrically relative to one another such that the gantry  40  may be rotated relative to the attachment mechanism  807  and support column  801 . In embodiments, the gantry  40  may rotate at least about 90° relative to the support column  801  (e.g., as is illustrated by  FIGS.  8 A- 8 C  and  FIGS.  9 A- 9 C ). 
     In some embodiments, the patient support  813  may move from a first configuration as shown in  FIGS.  8 A- 8 C  to a second configuration as shown in  FIGS.  9 A- 9 C . In the configuration of  FIGS.  8 A- 8 C , the first portion  815  of the patient support  813  may extend in a generally horizontal direction (i.e., parallel to the floor  819 ) and the second portion  817  may extend in a generally vertical direction (i.e., away from the floor  819 ). In the configuration of  FIGS.  9 A- 9 C , the second portion  817  of the patient support  813  may extend in a generally horizontal direction (i.e., parallel to the floor  819 ) and the first portion  815  may extend in a generally vertical direction. Put another way, the patient support  813  may tilt by a predetermined angle (e.g., ˜90°) relative to the floor  819  between the configuration shown in  FIGS.  8 A- 8 C  and the configuration shown in  FIGS.  9 A- 9 C . In embodiments, the table configuration of  FIGS.  8 A- 8 C  may be used for scanning a patient in a weight-bearing standing position and the table configuration of  FIGS.  9 A- 9 C  may be used for scanning a patient in a lying position. 
     In some embodiments, the patient support  813  may rotate (tilt) with respect to a linkage member  821  to which the patient support  813  is attached. In embodiments, the linkage member  821  may also rotate with respect to the floor  819 . For example, the linkage member  821  may be attached to a base  823  that may be mounted to the floor  819 . The linkage member  821  may rotate relative to the base  823 . The rotation of the linkage member  821  relative to the base  823  may raise and lower the patient support  813  relative to the floor  819 . A control system may provide coordinated rotational motion of the patient support  813  relative to the linkage member  821  and rotational motion of the linkage member  821  relative to the base  823  to move the table system from the configuration shown in  FIGS.  8 A- 8 C  to the configuration shown in  FIGS.  9 A- 9 C . An example of a patient table system that may be used with the system  800  is described in U.S. Provisional Patent Application No. 62/380,595 filed on Aug. 29, 2016, the entire contents of which are incorporated by reference herein. 
       FIGS.  9 A- 9 C  illustrate the system  800  performing an imaging scan of a patient  105  in a lying position. In particular, for an x-ray CT imaging system, the x-ray source and detector may rotate within the gantry  40  around the patient  105  while the gantry  40  is translated relative to the patient support  813  in a generally horizontal direction to perform a helical scan of a patient  105  lying on the patient support  813 . In the embodiment shown in  FIGS.  9 A- 9 C , the gantry  40 , attachment mechanism  807  and support column  801  may translate relative to the patient  105  and patient support  813 , which may be stationary during the scan. The gantry  40 , attachment mechanism  807  and the support column  801  may translate along the length of the base  802 . As shown in  FIGS.  9 A- 9 C , the gantry  40  may be displaced vertically on the support column  801  such that the patient  105  is aligned with the bore  116  of the gantry  40  and the imaging axis  114  extends along the length of the patient  105 . The gantry  40 , attachment mechanism  807  and the support column  801  may then translate along the base  802  in a horizontal direction from a first position as shown in  FIG.  9 A  with the gantry  40  located over the head of the patient  105 , to a second position as shown in  FIG.  9 B  with the gantry  40  located over the mid-section of the patient  105 , to a third position as shown in  FIG.  9 C  with the gantry  40  located over the feet of the patient  105 . The system  800  may perform a horizontal scan over the full length of the patient  105  or any selected portion thereof. 
     The base  802  and the support column  801  may include mating features that confine the translation of the support column in a horizontal direction along the length of the base  802 . In the example of  FIGS.  9 A- 9 C , the base  802  may include a horizontal guide, such as rails or tracks, that may mate with corresponding features at the bottom of the support column  801  to guide the translation of the support column  801  in a horizontal direction. A second drive mechanism may drive the translation of the support column  801  relative to the base  802 . A second drive mechanism  812  for translating the gantry  40  and support column  801  is schematically illustrated in  FIG.  10 A . The second drive mechanism may comprise, for example, a belt drive, a drive wheel, a lead screw, a ball screw, a pulley, etc. or various combinations therefore. The second drive mechanism may be mechanically coupled to and driven by one or more motors, which may be located in the support column  801  and/or the base  802 . The controller  810  (see  FIG.  10 A ) may control the operation of the second drive mechanism and thereby control the horizontal translation of the support column  801 , attachment mechanism  807  and gantry  40 . The controller may receive position feedback signals indicative of the position of the support column  801  relative to the base  802 , such as from a linear encoder. 
       FIGS.  10 A- 10 C  illustrate the system  800  performing an imaging scan of a patient  105  along a tilted axis. The patient  105  may be supported by the patient support  813  at an oblique angle such that an axis  1014  extending lengthwise through the patient  105  is neither parallel or perpendicular to the floor  819 . This may be achieved, for example, by rotating (tilting) the patient support  813  and patient  105  from a standing position (as shown in  FIGS.  8 A- 8 C ) or rotating (tilting) the patient support  813  and patient  105  upwards from a lying position (as shown in  FIGS.  9 A- 9 C ). The gantry  40  may be pivoted with respect to the support column  801  such that the imaging axis  114  through the bore  116  is parallel to, and optionally collinear with, the patient axis  1014 . The system  800  may perform an imaging scan (e.g., a helical x-ray CT scan) of the patient  105  by moving the gantry  40  in the direction of the tilted patient axis  1014  while maintaining a fixed angle between the gantry  40  and axis  1014 . In various embodiments, the controller  810  of the imaging system  800  may provide a coordinated movement of the gantry  40  and attachment mechanism  807  relative to the support column  801  in a vertical direction with a movement of the gantry  40 , attachment mechanism  807  and support column  801  relative to the base  802  in a horizontal direction. The controller  810  may include logic configured to determine the relative vertical and horizontal displacement of the gantry  40  needed to move the gantry  40  along the tilted axis  1014 . The controller  810  may send control signals to the first and second drive mechanisms  808 ,  812  as described above to provide coordinated vertical and horizontal displacement of the gantry  40 . Where the angle of the tilted axis  1014  is known or may be determined, the controller  810  may use simple trigonometric relations to determine the vertical and horizontal displacement of the gantry  40 . As in the embodiment of  FIGS.  5 A- 5 C , for example, where the tilted axis  1014  is at an angle of 60° relative to horizontal, each cm of the scan along the axis  1014  may include a vertical displacement of the gantry  40  relative to the support column  801  of ˜0.0.87 cm (i.e., sin 60°) and a horizontal displacement of the gantry  40  and support column  801  relative to the base  802  of 0.5 cm (i.e., cos 50°). Thus, the imaging system  800  may perform a scan at any tilt axis  1014 , and in embodiments may perform scans along complex axes, such as along an angled or curved axis. 
       FIGS.  10 A- 10 C  illustrate the system  800  performing an imaging scan of a patient  105  along a tilted axis  1014 . In particular, for an x-ray CT imaging system, the x-ray source and detector may rotate within the gantry  40  around the patient  105  while the gantry  40  is displaced in both vertical and horizontal directions to perform a helical scan of the patient  105  along a tilted axis  1014 . The patient may be supported on a patient support  813  that may be tilted such that the second portion  817  of the patient support  813  may extend parallel to the tilted axis  1014 . The gantry  40  may be pivoted with respect to the support column  801  to align the gantry imaging axis  814  with the tilted axis  1014 . The gantry  40  may be moved in both a vertical and horizontal direction from a first position as shown in  FIG.  10 A  with the located over the head of the patient  105 , to a second position as shown in  FIG.  10 B  with the gantry  40  located over the mid-section of the patient  105 , to a third position as shown in  FIG.  10 C  with the gantry  40  located over the feet of the patient  105 . The system  800  may perform scan over the full length of the patient  105  or any selected portion thereof. 
       FIGS.  11 A- 11 C  illustrate yet another embodiment of an imaging system  1100 . The imaging system  1100  in this embodiment is similar to the imaging system  100  described above with reference to  FIGS.  1 A- 5 C , and includes an imaging gantry  40  and a pair of support columns  31 ,  33  that extend vertically on opposite sides of the gantry  40 . The pair of support columns  31 ,  33  may be attached to opposite sides of the gantry by a pair of attachment mechanisms  201 ,  203 . The gantry  40  may be a generally O-shaped structure having a central imaging bore  116  and defining an imaging axis  114  extending through the bore. The imaging system  1100  may be an x-ray imaging system and the gantry  40  may contain one of more of the x-ray imaging components described above with reference to  FIG.  6   , such as an x-ray source, an x-ray detector, a high-voltage generator, a heat exchanger, a power supply (e.g., battery system), and a computer. 
     The imaging system  1100  further includes a base  102 , and the support columns  31 ,  33  extend vertically above a top surface of the base  102 . As shown in  FIG.  11 A , the gantry  40  is supported between the pair of support columns  31 ,  33  and above the top surface of the base  102 . In the configuration shown by  FIG.  11 A , the support columns  31 ,  33  support the gantry with the imaging axis  114  in a horizontal orientation. 
     Attachment mechanism  201  mates with at least one vertical rail  118  on support column  31 , and attachment mechanism  203  mates with at least one vertical rail  118  on support column  33 . The pair of attachment mechanisms  201 ,  203  are moveable along the vertical rails  118  of the support columns  31 ,  33  to cause the pair of attachment mechanisms  201 ,  203  and the gantry  40  to which they are attached to move up and down along the support columns  31 ,  33  in the direction of arrow  112 . A first drive mechanism (see  808  in  FIG.  10 A ) may move the attachment mechanisms  201 ,  203  and gantry  40  along the support members  31 ,  33 . 
     The support columns  31 ,  33 , the attachment mechanisms  201 ,  203  and the gantry  40  are moveable with respect to the base  102 . A second drive mechanism (see  812  in  FIG.  10 A ) may move the support columns  31 ,  33 , attachment mechanisms  201 ,  203  and gantry  40  back and forth along the base  102  in the direction of arrow  212 . The second drive mechanism may move the gantry  40 , attachment mechanisms  201 ,  203  and support columns  31 ,  33  in a horizontal direction along the base  102  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a helical CT scan of a human or animal patient positioned within the bore  116  (e.g., on a patient table, not illustrated in  FIG.  11 A ). 
     The base  102  may include a pair of horizontal guides  110 , and each of the support columns  31 ,  32  may move along a respective horizontal guide  110 . In the embodiment shown in  FIGS.  11 A- 11 C , the support columns  31 ,  33  may extend into the base  102 , and the horizontal guides  110  may include a pair of parallel slots  1105  within which the support columns  31 ,  33  may move. The support columns  31 ,  33  may also engage with a one or more guide rails, such as shown in  FIGS.  1 A- 5 C , which may be located inside the slots  1105 . 
     Each of the attachment mechanisms  201 ,  203  may attach to a side of the gantry  40  via a bearing assembly that allows the gantry  40  to pivot with respect to the support columns  31 ,  33 . As shown in  FIGS.  11 A- 11 B , the gantry  40  may pivot from a configuration in which the pair of support columns  31 ,  33  support the gantry  40  with the imaging axis  114  in a horizontal orientation (see  FIG.  11 A ) to a configuration in which the pair of support columns  31 ,  33  support the gantry  40  with the imaging axis  114  in a vertical orientation (see  FIG.  11 B ). The gantry  40  may also be pivoted to a configuration in which the support columns  31 ,  33  support the gantry  40  with the imaging axis  114  of the gantry  40  orientated along a tilted axis that is neither vertical nor horizontal, such as shown in  FIGS.  5 A- 5 C and  10 A- 10 C . 
     In embodiments, the first drive mechanism may move the pair of attachment mechanisms  201 ,  203  and the gantry  40  on the vertical rails  118  along the support columns  31 ,  33  while the support columns  31 ,  33  support the gantry  40  with the imaging axis  114  in a vertical orientation as shown in  FIG.  11 B  in order to perform a vertical scan of a human or animal patient located within the bore  116  of the gantry  40 . The patient may be scanned in a weight-bearing (e.g., standing) position. The attachment mechanisms  201 ,  203  and the gantry  40  may move vertically along the support columns  31 ,  33  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a helical CT scan of the patient. 
     In addition, while the support columns  31 ,  33  support the gantry  40  with the imaging axis  114  orientated along a tilted axis, a controller (see  810  in  FIG.  10 A ) may control the first and second drive mechanisms to move the gantry  40  in both vertical and horizontal directions in a coordinated manner in order to perform an x-ray imaging scan along the tilted axis, as described above with reference to  FIGS.  5 A- 5 C and  10 A- 10 C . 
     As shown in  FIGS.  11 A- 11 C , the base  102  of the imaging system  1100  may also include a cavity  1101  configured to receive the gantry  40  so that the gantry  40  is housed within the base  102 . The cavity  1101  may have a size and shape that corresponds to the size and shape of the gantry  40  while the support columns  31 ,  33  support the gantry  40  with the imaging axis  114  in a vertical orientation. The cavity  1101  may also be sized and shaped to accommodate the attachment mechanisms  201 ,  203 , as shown in  FIGS.  11 A- 11 C . 
     In the embodiment of  FIGS.  11 A- 11 C , the gantry  40  may be pivoted to a configuration in which the pair of support columns  31 ,  33  support the gantry  40  with the imaging axis  114  in a vertical orientation, as shown  FIG.  11 B . Optionally, the support columns  31 ,  33 , attachment mechanisms  201 ,  203  and gantry  40  may be moved along the base  102  on the horizontal guides  110  to position the gantry in alignment with the cavity  1101  in the base  102 . The first drive mechanism may move the gantry  40  and attachment mechanisms  201 ,  203  down along the vertical rails  118  of the support members  31 ,  33  to move the gantry  40  and attachment mechanisms  201 ,  203  into the cavity  1101  in the base  102 . 
     The cavity  1101  may have a depth that is at least as large as the width dimension of the gantry  40  so that the gantry  40  may fully enter the cavity  1101 . This may enable the gantry  40  to be moved completely out of the way and safely stored in the cavity  1101  when not in use. In the embodiment shown in  FIG.  11 C , the gantry  40  is moved into the cavity  1101  so that the outer surface of the gantry  40  is level with the top surface of the base  102 . In some embodiments, a door or similar cover (not illustrated in  FIG.  11 C ) may optionally be moved into place over the top of the cavity  1101  to fully enclose the gantry  40  within the cavity  1101 . As shown in  FIG.  11 C , the shape of the cavity  1101  may roughly correspond to both the outer and inner dimensions of the gantry  40  so that a portion  1103  of the base  102  interior of the cavity  1101  may fill the space within the bore  116  of the gantry  40  when the gantry  40  is located inside of the cavity  1101 . 
     When the imaging system  1100  is needed to perform an imaging scan, the first drive mechanism may move the gantry  40  and attachment mechanisms  201 ,  203  up along the vertical rails  118  of the support columns  31 ,  33  to move the gantry  40  and attachment mechanisms  201 ,  203  out of the cavity  1101 . The attachment mechanisms  201 ,  203  and the gantry  40  may move vertically along the support columns  31 ,  33  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a vertical imaging scan (e.g., a helical x-ray CT scan) of a patient in a weight-bearing position. The patient may stand on the portion  1103  of the base  102  interior of the cavity  1101  during the imaging scan. Alternately, the gantry  40  and attachment mechanisms  201 ,  203  may be raised out of the cavity  1101 , and the second drive mechanism may move the support columns  31 ,  33  along the horizontal guides  110  of the base  102  in order to move the gantry  40 , attachment mechanisms  201 ,  203  and support columns  31 ,  33  away from the cavity  1101  to a different portion of the base  102  in order to perform a vertical imaging scan. To perform an imaging scan in a horizontal direction or along a titled axis, the gantry  40  may be pivoted to a configuration in which the support columns  31 ,  33  support the gantry  40  with the imaging axis oriented in a horizontal direction or along a tilted axis that is neither vertical nor horizontal. The second drive mechanism may move the gantry  40 , attachment mechanisms  201 ,  203  and support columns  31 ,  33  in a horizontal direction along the base  102  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a helical CT scan of a human or animal patient positioned within the bore  116 . 
     Although the imaging system  1100  shown in  FIGS.  11 A- 11 C  includes a pair of support columns  31 ,  33  attached to opposite sides of the gantry  40 , it will be understood that alternative embodiments may include a single support column  801  that is mounted to a first side of the gantry  40  by an attachment mechanism  807  and that supports the gantry  40  in a cantilevered manner, such as shown in  FIGS.  8 A- 10 C . In addition, although the embodiment shown in  FIGS.  11 A- 11 C  includes a cavity  1101  for housing the gantry  40  located within the base  102  of the imaging system  1100 , it will be understood that in alternative embodiments, the cavity  1101  may be located in the floor. 
       FIGS.  12 A- 12 D  illustrate an alternative embodiment of an imaging system  1200  having a single support column supporting the imaging gantry and a cavity in the floor that is configured to receive the gantry. The imaging system  1200  in this embodiment may be similar to the imaging system  800  described above with reference to  FIGS.  8 A- 10 C , and includes a base  802 , a support column  801  located on and supported by the base  802 , and a gantry  40  supported by the support column  801  in a cantilevered manner. An attachment mechanism  807  may be attached to one side of the gantry  40 , and may be located between the side of the gantry  40  and the support column  801 . The attachment mechanism  807  may engage with vertical rails  805 ,  806  extending along the support column  801  that enable the gantry  40  and attachment mechanism  807  to move up and down along the support column  801 . 
     The floor surface may include a first portion  1201  and a second portion  1204 , where the first portion  1201  may be raised relative to the second portion  1204 . The base  802  of the imaging system  1200  may be located on the second portion  1204 , so that it is recessed relative to the first portion  1201 . In the embodiment of  FIGS.  12 A- 12 D , the raised portion  1201  is the upper surface of a platform. A ramp  1202  may extend between the raised portion  1201  and the second portion  1204  of the floor surface. 
     As shown in  FIGS.  12 A- 12 D , the first portion  1201  of the floor surface includes a cavity  1205  configured to receive the gantry  40 . The cavity  1205  may have a size and shape that corresponds to the size and shape of the gantry  40 .  FIG.  12 A  shows the gantry  40  located within the cavity  1205 . In the embodiment shown in  FIG.  12 A , the outer surface of the gantry  40  is level with the first portion  1201  of the floor surface. A section  1206  of the first portion  1201  of the floor surface that is interior of the cavity  1205  has a size and shape that corresponds to the size and shape of the bore  116  of the gantry  40 . This section  1206  fills the space within the bore  116  when the gantry  40  is in the cavity  1205 , as shown in  FIG.  12 A . In this embodiment, the cavity  1205  is located at a corner of the first portion  1201  of the floor surface, so that the first portion  1201  extends around a portion of the outer circumference of the gantry  40 .  FIG.  12 A  also illustrates a door  1207  that may be pivotably mounted to the first portion  1201  of the floor surface so that the door  1207  may be pivoted over the top of the cavity  1205  and cover at least a portion of the gantry  40 . 
     When the imaging system  1200  is needed to perform an imaging scan, a first drive mechanism (see  FIG.  10 A ) may move the gantry  40  and the attachment mechanism  807  up along the vertical rails  805 ,  806  of the support column  801  to move the gantry  40  and attachment mechanism  807  out of the cavity  1205 , as shown in  FIG.  12 B . The gantry  40  and attachment mechanism  807  may move vertically along the support column  801  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a vertical imaging scan (e.g., a helical x-ray CT scan) of a patient in a weight-bearing position. The patient may stand on the section  1206  of the floor surface  1201  interior of the cavity  1205  during the imaging scan. Alternately, the gantry  40  and attachment mechanism  807  may be raised out of the cavity  1205 , and a second drive mechanism may move the support column  801  along the length of the base  802  in order to move the gantry  40 , and attachment mechanism  807  away from the cavity  1205  to a different location for performing a vertical imaging scan. To perform an imaging scan in a horizontal direction or along a titled axis, the gantry  40  may be pivoted on a bearing assembly between the attachment mechanism  807  and the gantry  40  to a configuration in which the support column  801  supports the gantry  40  with the imaging axis oriented in a horizontal direction (as shown in  FIG.  12 C ) or along a tilted axis that is neither vertical nor horizontal (as shown in  FIG.  12 D ). The second drive mechanism may move the gantry  40 , attachment mechanism  807  and support column  801  in a horizontal direction along the base  802  in coordination with the rotation of x-ray imaging components around the bore  116  in order to perform a helical CT scan of a human or animal patient positioned within the bore  116 . 
     The foregoing method descriptions are provided merely as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of steps in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not necessarily intended to limit the order of the steps; these words may be used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular. 
     The preceding description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 
     
       
         
           
               
               
             
               
                 TABLE 
               
               
                   
               
               
                 Reference 
                   
               
               
                 Number 
                 Component Represented 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 31 
                 Support column 
               
               
                 33 
                 Support column 
               
               
                 35 
                 Docking system 
               
               
                 40 
                 Gantry 
               
               
                 41 
                 Rotor 
               
               
                 42 
                 Outer shell of gantry 
               
               
                 43 
                 X-ray source 
               
               
                 44 
                 High-voltage generator 
               
               
                 45 
                 X-ray detector 
               
               
                 46 
                 Computer 
               
               
                 47 
                 Rotor drive mechanism 
               
               
                 50 
                 Table Column 
               
               
                 60 
                 Tabletop support 
               
               
                 63 
                 Power supply 
               
               
                 100 
                 Imaging system 
               
               
                 101 
                 Rotating portion of imaging system 
               
               
                 102 
                 Base 
               
               
                 105 
                 Patient 
               
               
                 110 
                 Horizontal guide on base 
               
               
                 112 
                 Arrow indicating direction of displacement of gantry 
               
               
                 114 
                 Imaging axis 
               
               
                 116 
                 Bore 
               
               
                 118 
                 Vertical rail on support column 
               
               
                 201 
                 Attachment mechanism for attaching gantry to support 
               
               
                   
                 member 
               
               
                 202 
                 Support structure 
               
               
                 203 
                 Attachment mechanism for attaching gantry to support 
               
               
                   
                 member 
               
               
                 212 
                 Arrow indicating direction of relative displacement of 
               
               
                   
                 gantry and tabletop support 
               
               
                 400 
                 Bearing assembly 
               
               
                 402 
                 First race of bearing assembly 
               
               
                 404 
                 Second race of bearing assembly 
               
               
                 406 
                 Outer circumferential surface of outer shell of gantry 
               
               
                 412 
                 Side wall of outer shell of gantry 
               
               
                 430 
                 Heat exchanger 
               
               
                 514 
                 Tilted axis 
               
               
                 800 
                 Imaging system 
               
               
                 801 
                 Support column 
               
               
                 802 
                 Base 
               
               
                 805, 806 
                 Vertical rails 
               
               
                 807 
                 Attachment mechanism for attaching gantry to support column 
               
               
                 808 
                 First drive mechanism that moves the attachment mechanism 
               
               
                   
                 and the gantry along the support column 
               
               
                 809 
                 Interior housing of support column 
               
               
                 810 
                 Controller 
               
               
                 811 
                 Opening along length of support column 
               
               
                 812 
                 Second drive mechanism that moves the support column, 
               
               
                   
                 attachment mechanism and gantry along the base 
               
               
                 813 
                 Patient support 
               
               
                 815 
                 First portion of patient support 
               
               
                 817 
                 Second portion of patient support 
               
               
                 819 
                 Floor 
               
               
                 821 
                 Linkage member attached to patient support 
               
               
                 823 
                 Base mounted to floor and attached to linkage member 
               
               
                 1014 
                 Axis extending lengthwise through patient 
               
               
                 1100 
                 Imaging system 
               
               
                 1105 
                 Parallel slots in base 
               
               
                 1101 
                 Cavity in the base 
               
               
                 1103 
                 Portion of the base interior of the cavity 
               
               
                 1200 
                 Imaging system 
               
               
                 1201 
                 First portion of floor surface that is raised relative to a 
               
               
                   
                 second portion 
               
               
                 1202 
                 Ramp 
               
               
                 1204 
                 Second portion of floor surface that is recessed relative to 
               
               
                   
                 the first portion 
               
               
                 1205 
                 Cavity configured to receive the gantry 
               
               
                 1206 
                 Section of floor surface interior of the cavity 
               
               
                 1207 
                 Door