Patent Publication Number: US-2019175431-A1

Title: Surgical table and method of operating the same

Description:
FIELD OF THE INVENTION 
     The present invention relates to surgical tables and to methods of operating surgical tables. 
     BACKGROUND 
     Surgical tables, or operating tables, comprising a base for standing on a floor, a column extending from the base, and a tabletop providing a patient support surface are well known. 
     In order for surgical tables to be versatile, it is necessary for the tabletop to be disposable in a variety of different configurations. WO2003/030802 discloses a surgical table with mechanisms for inclining a tabletop of the table relative to a column of the table and relative to the horizontal about both transverse and longitudinal axes of the tabletop, and a drive assembly for permitting a traverse movement of the tabletop relative to the column in back and forth longitudinal directions of the tabletop. 
     Anthropometric data of the world&#39;s population is shifting over time. 
     SUMMARY OF THE INVENTION 
     There is a need for a surgical table with a more compact mechanism for disposing a tabletop in a variety of different configurations. 
     There also is a need for a surgical table with a mechanism for disposing a tabletop in a greater variety of different configurations, in order to increase the versatility of the surgical table for serving the population as anthropometric data shifts over time. 
     Surgical tables may have a tabletop and a column that are movable relative to each other between first and second relative positions via a predetermined relative position, such as a predetermined default or home position. Such a predetermined relative position may be, for example, the position at which a patient is most easily transferrable onto or from the table, the position at which the table is most stable, or the position at which the table is best placed to enable a certain procedure to be performed on a patient supported by the table. 
     There is a need for a surgical table having an assistance mechanism for helping medical staff using the surgical table to dispose a tabletop and a column of a surgical table at such a predetermined relative position. 
     A first aspect of the present invention provides a surgical table comprising: a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; and a tabletop traverse drive mechanism coupling the tabletop to the column, which tabletop traverse drive mechanism is for causing movement of the tabletop relative to the column in a selected longitudinal or transverse direction of the tabletop; wherein the tabletop traverse drive mechanism comprises a driver, first and second drive elements that are drivable by the driver, and a traverse device that is drivable by each of the first and second drive elements, the first and second drive elements being movably mounted on one of the column and the tabletop and the traverse device being mounted on the other of the column and the tabletop; and wherein the driver is operable to drive the first and second drive elements to drive the traverse device to cause movement of the tabletop relative to the column between a predetermined traverse position, at which both of the first and second drive elements are engaged with the traverse device, and a first traverse position, at which the first drive element is engaged with the traverse device and the second drive element is disengaged from the traverse device. 
     Optionally, the driver is operable to drive the first and second drive elements to drive the traverse device to cause movement of the tabletop relative to the column to a second traverse position, at which the second drive element is engaged with the traverse device and the first drive element is disengaged from the traverse device. 
     Optionally, the first and second drive elements are movably mounted on the column and the traverse device is mounted on the tabletop. 
     Optionally, the first and second drive elements are rotatably mounted on the one of the column and the tabletop. 
     Optionally, the first and second drive elements are mounted for rotation about respective first and second axes that are both perpendicular to the longitudinal direction of the tabletop, or that are both parallel to the longitudinal direction of the tabletop. Optionally, one or each of the first and second axes is perpendicular to a lateral direction of the tabletop, which lateral direction of the tabletop is perpendicular to the longitudinal direction of the tabletop. Optionally, one or each of the first and second axes is parallel to a lateral direction of the tabletop, which lateral direction of the tabletop is perpendicular to the longitudinal direction of the tabletop. 
     Optionally, the first and second drive elements are meshed with the traverse device when the tabletop is at the predetermined traverse position. 
     Optionally, the first and second drive elements are first and second pinion gears. 
     Optionally, the traverse device is a rack. 
     Optionally, the traverse device is linear and aligned with the longitudinal direction of the tabletop. 
     Optionally, the first and second drive elements are spaced apart in a direction that is parallel to the longitudinal direction of the tabletop. 
     Optionally, the driver comprises a motor connected to both the first and second drive elements for driving both the first and second drive elements. 
     Optionally, the surgical table comprises a controller for controlling operation of the tabletop traverse drive mechanism. Optionally, the controller is configured to control the tabletop traverse drive mechanism to cause movement of the tabletop relative to the column between the first and second traverse positions via the predetermined traverse position, and configured, when the tabletop is at the predetermined traverse position relative to the column, to control the tabletop traverse drive mechanism to cause the movement of the tabletop relative to the column to be paused for a predetermined period of time. 
     Optionally, the surgical table comprises a sensor for sensing, and for notifying the controller of, a relative position of the tabletop and the column. Optionally, the sensor is for sensing, and for notifying the controller of, when the tabletop is at the predetermined traverse position relative to the column. 
     Optionally, the predetermined period of time is between 0.05 and 5 seconds. Further optionally, the predetermined period of time is between 0.1 and 3 seconds. Further optionally, the predetermined period of time is between 0.25 and 2 seconds. 
     A second aspect of the present invention provides a surgical table comprising a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; a tabletop traverse drive mechanism coupling the tabletop to the column, which tabletop traverse drive mechanism is for causing movement of the tabletop relative to the column in a selected longitudinal or transverse direction of the tabletop; and a controller for controlling operation of the tabletop traverse drive mechanism; wherein the controller is configured to control the tabletop traverse drive mechanism to cause movement of the tabletop relative to the column between first and second traverse positions via a predetermined traverse position, and configured, when the tabletop is at the predetermined traverse position relative to the column, to control the tabletop traverse drive mechanism to cause the movement of the tabletop relative to the column to be paused for a predetermined period of time. 
     Optionally, the tabletop traverse drive mechanism is for causing movement of the tabletop relative to the column in a selected longitudinal direction of the tabletop. 
     Optionally, the surgical table comprises a sensor for sensing, and for notifying the controller of, a relative position of the tabletop and the column. Optionally, the sensor is for sensing, and for notifying the controller of, when the tabletop is at the predetermined traverse position relative to the column. 
     Optionally, the predetermined period of time is between 0.05 and 5 seconds. Further optionally, the predetermined period of time is between 0.1 and 3 seconds. Further optionally, the predetermined period of time is between 0.25 and 2 seconds. 
     A third aspect of the present invention provides a method of operating a surgical table having a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; a tabletop traverse drive mechanism coupling the tabletop to the column, which tabletop traverse drive mechanism is for causing movement of the tabletop relative to the column in a selected longitudinal or transverse direction of the tabletop; and a controller for controlling operation of the tabletop traverse drive mechanism, the method comprising: the controller controlling the tabletop traverse drive mechanism to cause movement of the tabletop relative to the column between first and second traverse positions via a predetermined traverse position; and the controller controlling the tabletop traverse drive mechanism to cause the movement of the tabletop relative to the column to be paused for a predetermined period of time when the tabletop is at the predetermined traverse position relative to the column. 
     Optionally, the tabletop traverse drive mechanism is for causing relative movement of the tabletop relative to the column in a selected longitudinal direction of the tabletop. 
     Optionally, the method comprises sensing a relative position of the tabletop and the column. Further optionally, the method comprises sensing when the tabletop is at the predetermined traverse position relative to the column. 
     Optionally, the predetermined period of time is between 0.05 and 5 seconds. Further optionally, the predetermined period of time is between 0.1 and 3 seconds. Further optionally, the predetermined period of time is between 0.25 and 2 seconds. 
     A fourth aspect of the present invention provides a computer program product for causing a surgical table to perform the method of the third aspect of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic side view of a surgical table in accordance with an embodiment of the present invention; 
         FIG. 2A  is a top plan view of a top portion of the column and the lower torso section of the surgical table of  FIG. 1 , with the mattress of the lower torso section removed and with the lower torso section at a predetermined traverse position relative to the column; 
         FIG. 2B  is a side view of the components shown in  FIG. 2A ; 
         FIG. 2C  is a bottom view of the components shown in  FIG. 2A ; 
         FIG. 3A  is a top plan view of a top portion of the column and the lower torso section of the surgical table of  FIG. 1 , with the mattress of the lower torso section removed and with the lower torso section at a first traverse position relative to the column; 
         FIG. 3B  is a side view of the components shown in  FIG. 3A ; 
         FIG. 3C  is a bottom view of the components shown in  FIG. 3A ; 
         FIG. 4A  is a top plan view of a top portion of the column and the lower torso section of the surgical table of  FIG. 1 , with the mattress of the lower torso section removed and with the lower torso section at a second traverse position relative to the column; 
         FIG. 4B  is a side view of the components shown in  FIG. 4A ; and 
         FIG. 4C  is a bottom view of the components shown in  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a surgical table, designated generally as  2 , includes a base  4 , which stands on a floor  6 , a column  8  of adjustable height extending from the base  4  and a tabletop  10  providing a patient support surface  12 . In a variation to this embodiment, the column  8  is not of adjustable height. The base  4  may include wheels for moving the table  2  along the floor  6 . 
     As depicted in  FIG. 1 , the tabletop  10  is divided into five sections, namely a head section  14 , an upper torso section  16 , a lower torso section  18  and a pair of laterally adjacent leg sections  20 ,  20 , of which only one is shown in  FIG. 1 . Each of the sections of the tabletop  10  provides a portion of the patient support surface  12 , and each of the sections has a respective separate mattress  22 ,  24 ,  26 ,  28 ,  28 . 
     The lower torso section  18  is coupled to the column  8 . A lower end  35  of the upper torso section  16  is detachably mounted on an upper end  41  of the lower torso section  18  by means of transversely adjacent first and second pivot joints  30 ,  32 , which define a transverse axis about which the upper torso section  16  can be displaced relative to the lower torso section  18 . 
     Each of the leg sections  20  is detachably mounted on a lower end  42  of the lower torso section  18  by a respective one of transversely adjacent third and fourth pivot joints  44 ,  46 , of which only one is visible in  FIG. 1 , for displacement relative to the lower torso section  18  about a transverse axis defined by the respective one of third and fourth pivot joints  44 ,  46 . 
     A lower end  34  of the head section  14  is detachably mounted on an upper end  36  of the upper torso section  16  by means of a fifth pivot joint  38  defining a transverse axis about which the head section  14  can be displaced relative to the upper torso section  16 . The angle of inclination of the head section  14  is controlled manually by means of a pair of conventional adjustable struts  40 , only one of which is shown in  FIG. 1 , secured to and extending between the underside of the head section  14  and the upper torso section  16 , one on each side of the tabletop  10 . The struts  40  may be hydraulic or electric actuators or lockable gas springs. 
     The provision of the five pivot joints  30 ,  32 ,  38 ,  44 ,  46  permits the five sections  14 ,  16 ,  18 ,  20 ,  20  selectively to be inclined relative to adjacent sections  14 ,  16 ,  18 ,  20 ,  20  thereby to dispose the tabletop  10  in a selected configuration. Moreover, that the head section  14  is detachable from the upper torso section  16 , and each of the upper torso section  16  and the leg sections  20 ,  20  is detachable from the lower torso section  18  means that the table  2  may be made compact for storage. 
     Although not expressly shown in the Figures, the surgical table  2  of this embodiment also includes a mechanism for inclining the whole tabletop  10  relative to the column  8  and relative to the horizontal about transverse and longitudinal axes of the tabletop  10 . Inclination about the transverse axis of the tabletop  10  is referred to in the art as “trending”, while inclination about the longitudinal axis of the tabletop  10  is referred to as “tilting”. Compound movements also are possible, in which the tabletop  10  is inclined about both the transverse and longitudinal axes of the tabletop  10  at the same time. 
     As used herein, the longitudinal axis of the tabletop is the major axis of the tabletop and the transverse axis of the tabletop is the orthogonal minor axis of the tabletop. The longitudinal direction of the tabletop is parallel to the major axis and the transverse direction of the tabletop is parallel to the minor axis. That is, the transverse direction of the tabletop is perpendicular to, or orthogonal to, the longitudinal direction of tabletop. 
     In variations to the illustrated embodiment, the tabletop  10  may be divided into a different number and/or configuration of sections to those shown in the Figures, or may not be divided into multiple sections at all. In such variations, the tabletop  10  may not include any sections that are relatively inclinable to each other by pivoting about a transverse axis defined by a pivot joint. In some such variations, the table  2  still includes a mechanism for inclining the whole tabletop  10  relative to the column  8  and/or relative to the horizontal about transverse and/or longitudinal axes of the tabletop  10 . In other variations, no such mechanism is provided, and the whole tabletop  10  is not inclinable relative to the column  8  and relative to the horizontal. 
     The surgical table  2  further is provided with a tabletop traverse drive mechanism  100  mounted between the underside of the tabletop  10  and the top of the column  8  for causing movement of the tabletop  10  relative to the column  8  in a selected longitudinal direction of the tabletop  10 . The tabletop  10  is coupled to the column  8  via the tabletop traverse drive mechanism  100 , with the tabletop traverse drive mechanism  100  permitting relative movement of the tabletop  10  and the column  8 . Operation of the tabletop traverse drive mechanism  100  is controlled by a controller (not shown) of the surgical table  2 . The controller controls the tabletop traverse drive mechanism  100  in dependence on one or more instructions received at the controller from a user interface (not shown) of the operating table. 
     Referring to  FIGS. 2A to 2C , the tabletop traverse drive mechanism  100  comprises a driver in the form of a motor (not shown), a drive gear  102  for being driven by the motor, first and second drive elements in the form of first and second pinion gears  104 ,  106  that are meshed with the drive gear  102  so as to be drivable by the motor via the drive gear  102 , and a traverse device in the form of a rack  108  that is meshed with the first and second pinion gears  104 ,  106  so as to be drivable by each of the first and second pinion gears  104 ,  106 . The motor may be an electrically-powered motor. Any suitable mechanism for causing the drive gear  102  to be driven by the motor may be provided. For example, the drive gear  102  may be fixed to a spindle of the motor, so that rotation of the spindle about an axis causes rotation of the drive gear  102  about the same axis. Alternatively, the drive gear  102  may be indirectly connected to a spindle of the motor, such as by one or more further gears. For example, a primary gear (not shown), such as a worm gear, may be fixed to the spindle of the motor, which primary gear is meshed with the drive gear  102  so that rotation of the spindle causes rotation of the primary gear which, in turn, causes rotation of the drive gear  102 . 
     In the illustrated embodiment, the motor is mounted on the column  8  beneath a cover  40  covering a top of the column  8 , the drive gear  102  and first and second pinion gears  104 ,  106  are rotatably mounted on the column  8  beneath the cover  40 , and the rack  108  is mounted on an inner side of a first frame member  18   a  of a pair of lateral frame members  18   a ,  18   b  of the lower torso section  18  of the tabletop  10 . In variations to this embodiment, the motor is mounted on the tabletop  10 , the drive gear  102  and first and second pinion gears  104 ,  106  are rotatably mounted on the tabletop  10 , and the rack  108  is mounted on the column  8 . 
     The first and second pinion gears  104 ,  106  are mounted on the column  8  for rotation about respective first and second axes A 1 , A 2 , which axes A 1 , A 2  are both perpendicular to the longitudinal direction of the tabletop  10 . Moreover, the axes A 1 , A 2  are both perpendicular to a lateral direction of the tabletop  10 , which lateral direction of the tabletop  10  is perpendicular to the longitudinal direction of the tabletop  10 . This arrangement minimises the vertical height of the first and second pinion gears  104 ,  106 , which permits the patient support surface  12  to be low. The first and second pinion gears  104 ,  106 , and their respective first and second axes A 1 , A 2 , are spaced apart in a direction that is parallel to the longitudinal direction of the tabletop  10 , and the rack  108  is linear and aligned with the longitudinal direction of the tabletop  10 . That is, the rack  108  has finite length and two opposed ends  108   a ,  108   b  that are spaced apart in a direction that is parallel to the longitudinal direction of the tabletop  10 . 
     In variations to the illustrated embodiment, one or each of the axes A 1 , A 2  is parallel to the longitudinal direction of the tabletop  10  or parallel to the lateral direction of the tabletop  10 . In some embodiments, one of the axes A 1 , A 2  is perpendicular to the lateral direction of the tabletop  10 , while the other of the axes A 1 , A 2  is parallel to the lateral direction of the tabletop  10 . 
     The tabletop traverse drive mechanism  100  further comprises first and second telescopic stabiliser arms  120 ,  130  slidably connected between respective lateral sides of the column  8  and respective ones of the pair of lateral frame members  18   a ,  18   b  of the lower torso section  18  of the tabletop  10 . More particularly, a first track  122  of the first telescopic stabiliser arm  120  is slidably engaged with a track  8   a  on a first lateral side of the column  8 , and a second track  124  of the first telescopic stabiliser arm  120  is slidably engaged with a track  18   c  on the first frame member  18   a  of the lower torso section  18  of the tabletop  10 . Similarly, a first track  132  of the second telescopic stabiliser arm  130  is slidably engaged with a track  8   b  on a second lateral side of the column  8 , and a second track  134  of the second telescopic stabiliser arm  130  is slidably engaged with a track  18   d  on the second frame member  18   b  of the upper torso section  16  of the tabletop  10 . 
     Although not expressly shown in the Figures, each of a first pair of cooperable stop features is provided on a respective one of the first track  122  of the first telescopic stabiliser arm  120  and the track  8   a  on the first lateral side of the column  8 , to limit the possible range of movement of the first track  122  relative to the track  8   a  back and forth in the longitudinal direction of the tabletop  10 . Each of a second pair of cooperable stop features is provided on a respective one of the second track  124  of the first telescopic stabiliser arm  120  and the track  18   c  on the first frame member  18   a  of the lower torso section  18  of the tabletop  10 , to limit the possible range of movement of the second track  124  relative to the track  18   c  back and forth in the longitudinal direction of the tabletop  10 . Each of a third pair of cooperable stop features is provided on a respective one of the first track  132  of the second telescopic stabiliser arm  130  and the track  8   b  on the second lateral side of the column  8 , to limit the possible range of movement of the first track  132  relative to the track  8   b  back and forth in the longitudinal direction of the tabletop  10 . Each of a fourth pair of cooperable stop features is provided on a respective one of the second track  134  of the second telescopic stabiliser arm  130  and the track  18   d  on the second frame member  18   b  of the lower torso section  18  of the tabletop  10 , to limit the possible range of movement of the second track  134  relative to the track  18   d  back and forth in the longitudinal direction of the tabletop  10 . The first to fourth pairs of cooperable stop features together limit the possible range of movement of the tabletop  10  relative to the column  8  back and forth in the longitudinal direction of the tabletop  10 . 
     Operation of the tabletop traverse drive mechanism  100  will now be described. 
     In  FIGS. 2A to 2C , the tabletop  10  is shown at a predetermined traverse position relative to the column  8  with both of the first and second pinion gears  104 ,  106  meshed with the rack  108 . When a user wishes to traverse the tabletop  10  relative to the column  8 , they operate the user interface to cause the user interface to send an instruction to the controller, which causes the controller to cause the motor to be energised, to operate in either a forward or reverse rotational mode in dependence on a content of the instruction from the user interface. The energisation of the motor causes the drive gear  102  to be rotated by the motor, thereby causing the first and second pinion gears  104 ,  106  to be longitudinally driven along the rack  108 . Accordingly, the rack  108 , which is rigidly attached to the lower torso section  18  of the tabletop  10 , is longitudinally driven back or forth relative to the column  8  to which the first and second pinion gears  104 ,  106 , the drive gear  102  and also the motor, are mounted. This traverses the tabletop  10  back and forth relative to the column  8 . 
     The controller is operable, via the user interface, to cause the motor to drive the first and second pinion gears  104 ,  106  to drive the rack  108 , in order to cause movement (in the direction of arrow A in  FIG. 3C ) of the tabletop  10  relative to the column  8  between the predetermined traverse position, illustrated in  FIGS. 2A to 2C , and a first traverse position, illustrated in  FIGS. 3A to 3C . During movement of the tabletop  10  relative to the column  8  from the predetermined traverse position towards the first traverse position, the first and second pinion gears  104 ,  106  are driven along the rack  108 . Before the tabletop  10  reaches the first traverse position, the second pinion gear  106  is driven off the second end  108   b  of the rack  108 . However, the first pinion gear  104  remains meshed with the rack  108 , so that the rack  108  is drivable by the first pinion gear  104  and continued driving of the first pinion gear  104  by the motor continues to move the tabletop  10  relative to the column  8  until the tabletop  10  reaches the first traverse position relative to the column  8 . When the tabletop  10  is at the first traverse position relative to the column  8 , the first pinion gear  104  still is engaged with the rack  108  but the second pinion gear  106  is disengaged from the rack  108 . That is, there is no contact between the second pinion gear  106  and the rack  108 . 
     Similarly, the controller also is operable, via the user interface, to cause the motor to drive the first and second pinion gears  104 ,  106  to drive the rack  108 , in order to cause movement (in the direction of arrow B in  FIG. 4C ) of the tabletop  10  relative to the column  8  between the predetermined traverse position, illustrated in  FIGS. 2A to 2C , and a second traverse position, illustrated in  FIGS. 4A to 4C . During movement of the tabletop  10  relative to the column  8  from the predetermined traverse position towards the second traverse position, the first and second pinion gears  104 ,  106  are driven along the rack  108 . Before the tabletop  10  reaches the second traverse position, the first pinion gear  104  is driven off the first end  108   a  of the rack  108 . However, the second pinion gear  106  remains meshed with the rack  108 , so that the rack  108  is drivable by the second pinion gear  106  and continued driving of the second pinion gear  106  by the motor continues to move the tabletop  10  relative to the column  8  until the tabletop  10  reaches the second traverse position relative to the column  8 . When the tabletop  10  is at the second traverse position relative to the column  8 , the second pinion gear  106  still is engaged with the rack  108  but the first pinion gear  104  is disengaged from the rack  108 . That is, there is no contact between the first pinion gear  104  and the rack  108 . 
     It will thus be appreciated that, through the provision of the tabletop traverse drive mechanism, the tabletop is movable relative to the column in the longitudinal direction of the tabletop over a distance that is greater than the length of the traverse device (the rack  108 , in the illustrated non-limiting example embodiment) in the longitudinal direction of the tabletop. The distance is not limited to the length of the traverse device (the rack  108 , in the illustrated non-limiting example embodiment). Thus, there is provided a compact mechanism for disposing a tabletop over a broader range of positions relative to the column, which increases the versatility of the surgical table. 
     Moreover, in embodiments of the invention (such as the illustrated embodiment) in which the surgical table includes a mechanism for inclining the tabletop relative to the horizontal about a transverse axis of the tabletop, due to the provision of the tabletop traverse drive mechanism there is provided a compact mechanism for inclining the tabletop at a steep angle relative to the horizontal when the tabletop is positioned at or near to one or other of its longitudinal limits relative to the column. Accordingly, there is provided a compact mechanism for disposing a tabletop in a still greater variety of different configurations, in order to increase the versatility of the surgical table. 
     In the illustrated embodiment, the driver of the tabletop traverse drive mechanism  100  comprises a single motor connected to both the first and second pinion gears  104 ,  106  for driving both the first and second pinion gears  104 ,  106 . The use of a single motor minimises complexity of the tabletop traverse drive mechanism and complexity of control of the tabletop traverse drive mechanism. In variations to this embodiment, the driver may instead comprise a first motor connected to the first pinion gear  104  for driving the first pinion gear  104 , and a second motor connected to the second pinion gear  106  for driving the second pinion gear  106 . 
     In the illustrated embodiment, the first and second drive elements are able to mesh with the traverse device. Such meshing reduces or eliminates slipping between the drive elements and the traverse device, which results in smooth and steady traversing of the tabletop, reduced wear of the tabletop traverse drive mechanism, and the ability to accurately position the tabletop relative to the column. Each of the first and second drive elements is made from hardened steel and, preferably, has surfaces having a low coefficient of friction. In a variation to this embodiment, the first and second drive elements do not mesh with the traverse device. For example, the first and second drive elements may comprise first and second wheels with smooth circumferential surfaces, and the traverse device may comprise a smooth plate along which the first and second wheels are driven. In such embodiments, preferably one or both of the surface of the plate and the circumferential surfaces of the first and second wheels have a high coefficient of friction (e.g. through being made of rubber or an elastomer), to reduce or eliminate slipping between the wheels and the plate. 
     As discussed above, the tabletop  10  is traversable in a longitudinal direction relative to the column  8 . The table  2  of the illustrated embodiment includes an assistance mechanism for helping medical staff using the table  2  to move the tabletop  10  relative to the column  8  in a selected longitudinal direction of the tabletop  10  to dispose the tabletop  10  and the column  8  at a predetermined relative position, such as a predetermined default or home position. 
     In dependence on movement instruction(s) received at the controller from the user interface of the surgical table  2 , the controller is configured to control the tabletop traverse drive mechanism  100  to cause movement of the tabletop  10  relative to the column  8  between the first and second positions via the predetermined traverse position. When the tabletop  10  is at the predetermined traverse position relative to the column  8 , the controller controls the tabletop traverse drive mechanism  100  to cause the movement of the tabletop  10  relative to the column  8  to be paused for a predetermined period of time. In this embodiment, the predetermined period of time is 2 seconds. However, in variations to this embodiment, the predetermined period of time may be any time between 0.05 and 5 seconds, more preferably between 0.1 and 3 seconds, more preferably between 0.25 and 2 seconds, and most preferably between 1 and 2 seconds. The controller is configured such that, if after elapse of the predetermined period of time the controller still is receiving from the user interface the movement instruction(s) to control the tabletop traverse drive mechanism  100  to cause the movement of the tabletop  10  relative to the column  8 , then the controller controls the tabletop traverse drive mechanism  100  to cause the movement of the tabletop  10  relative to the column  8  to be resumed. The controller also is configured such that, if after elapse of the predetermined period of time the controller no longer is receiving from the user interface the movement instruction(s) to control the tabletop traverse drive mechanism  100  to cause the movement of the tabletop  10  relative to the column  8 , then the controller controls the tabletop traverse drive mechanism  100  to cause the movement of the tabletop  10  relative to the column  8  not to be resumed. 
     In this embodiment, the table includes a sensor (not shown) communicatively connected to the controller. The sensor comprises a rotary encoder (not shown) fitted to the spindle of the motor and configured to output to the controller an indication of the current position of the spindle. Using the output of the rotary encoder, the controller keeps track of the current position of the spindle and, thus, is able to determine a current position of the tabletop  10  relative to the column  8 . The controller determines when the tabletop  10  is at the predetermined traverse position relative to the column  8  using the output of the rotary sensor. The controller may determine when the tabletop  10  is at the predetermined traverse position relative to the column  8  based on the number of detected rotations of the motor of the tabletop traverse drive mechanism  100  since the tabletop  10  began moving from one or other of the first and second traverse positions. 
     The sensor may also or alternatively comprise a rotary potentiometer connected by a drive wheel to one of the drive elements  104 ,  106  and configured to output to the controller an indication of the current position of the drive element  104 ,  106 . Using the output of the rotary potentiometer, the controller keeps track of the current position of the drive element  104 ,  106  and, thus, is able to determine a current position of the tabletop  10  relative to the column  8 . Additionally or alternatively, a cable potentiometer may be used. 
     In variations to this embodiment, the sensor may comprise a micro switch mounted at the top of the column  8 , and a portion of the tabletop  10  may be configured to actuate the micro switch when the portion of the tabletop  10  passes the micro switch. The micro switch and the portion of the tabletop  10  are relatively disposed so that the portion of the tabletop  10  actuates the micro switch when the tabletop  10  is at the predetermined traverse position relative to the column  8 . In still further variations, the sensor could take forms other than a micro switch and/or could comprise components located at different places on the table. 
     In variations to this embodiment, the controller may determine when the tabletop  10  is at the predetermined traverse position relative to the column  8  based on time elapsed since the tabletop  10  began moving from one or other of the first and second traverse positions at a known speed. Other mechanisms for determining when the tabletop  10  is at the predetermined traverse position relative to the column  8  also are usable. 
     It will thus be appreciated that, through the provision of the assistance mechanism, users of the surgical table are alerted as to when the tabletop is at the predetermined traverse position relative to the column, and are given the predetermined period of time in which to cause the user interface to stop sending the movement instruction(s) to the controller. Thus, there is provided a mechanism for helping users of the surgical table to dispose the tabletop of the surgical table at the predetermined traverse position relative to the column. 
     The controller may be connected to memory storing instructions for causing the controller to carry out one of the inventive methods of the present invention. Such memory may be considered to be an example of a computer program product for causing an apparatus, such as the controller, to perform one of the inventive methods of the present invention. 
     Various modifications can be made to the above-described embodiments without departing from the scope of the present invention, which is defined by the claims. 
     For example, in variations to the illustrated embodiment, in addition to or instead of the surgical table being provided with the tabletop traverse drive mechanism for causing movement of the tabletop relative to the column in a selected longitudinal direction of the tabletop, the surgical table is provided with a tabletop traverse drive mechanism mounted between the underside of the tabletop and the top of the column for causing movement of the tabletop relative to the column in a selected transverse direction of the tabletop. Such an additional or alternative, respectively, tabletop traverse drive mechanism may have any or all of the features and operation of the illustrated tabletop traverse drive mechanism, but in order to permit movement of the tabletop relative to the column in a selected transverse direction of the tabletop rather than in a selected longitudinal direction of the tabletop. Through the provision of such an additional or alternative, respectively, tabletop traverse drive mechanism, the tabletop is movable relative to the column in the transverse direction of the tabletop over a distance that is greater than the length of the traverse device (which may be a rack, similar to the rack  108 ) in the transverse direction of the tabletop. The distance is not limited to the length of the traverse device. Thus, there is provided a compact mechanism for transversely positioning the tabletop e.g. within an imaging device in order to image a patient on the tabletop. 
     Moreover, in such variations to the illustrated embodiment, the surgical table may include an assistance mechanism for helping medical staff using the table to move the tabletop relative to the column in a selected transverse direction of the tabletop to dispose the tabletop and the column at a predetermined relative position, such as a predetermined default or home position. 
     In variations to the above-described embodiments, the surgical table may have none, or only either one, of the above-described assistance mechanisms.