X-ray examination installation with coordinated positioning of the imaging system and the patient support mechanism

An x-ray examination installation includes an imaging system having components disposed on opposite sides of a patient on a patient support table. Positioning of the imaging system is coordinated with positioning of the patient support system in that the components of the imaging system are automatically moved, upon positioning of the patient support system, in a direction opposite to the movement of the patient support table. The range of adjustment of the patient support table can be sub-divided into ranges to which separate switching stages are allocated, so that the movement of the imaging system in a direction opposite to movement of the patient support table occurs only within predetermined ranges, so that such movement is not effected when the patient support table is adjusted within a central range.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed to an x-ray examination installation 
having an imaging system and a patient support system, both of which are 
adjustable in position. 
2. Description of the Prior Art 
X-ray installations are known wherein a patient being examined is supported 
on a table which is adjustable in two dimensions, and wherein the patient 
and the patient support table are surrounded by a C-arm, with opposite 
ends at which an x-ray source and an x-ray image intensifier are 
respectively mounted. Adjustment of the patient relative to the imaging 
system can be undertaken both by adjusting the position of the patient 
support table and by adjusting the position of the imaging system carried 
on the C-arm. The respective adjustments of these two systems are not 
coordinated with each other. This means that the alignment of the patient 
with respect to the imaging system must be accomplished by separate and 
individual adjustment of the position of the patient support table and of 
the imaging system. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an x-ray examination 
installation having an imaging system and a patient support system wherein 
adjustment of the position of the patient relative to the imaging system 
is simplified and can be accomplished faster than in known systems. 
The above object is achieved in accordance with the principles of the 
present invention in an x-ray examination installation wherein control 
means is provided such that, given a manual adjustment of the patient 
support table, the imaging system is automatically moved in a direct 
opposite to the direction of movement of the patient support table. The 
positioning of the imaging system can be accomplished by a motor-driven 
adjustment mechanism with control circuitry which provides signals for 
operating the motor which follow the movement of the patient support table 
in an opposite direction. The two motions are coordinated, for example, so 
that given a dislocation of the patient support table in the longitudinal 
direction, an oppositely directed, motor-driven displacement of the 
imaging system takes place, thereby providing a rapid adjustment of the 
position of the patient relative to the imaging system. 
In a further embodiment of the invention, the entire range of possible 
movement (adjustment) of the patient support table is sub-divided into a 
number of ranges, with a switching stage being allocated to each range, 
and the control means generates signals to effect an opposite movement of 
the imaging system only when the movement of the patient support table 
occurs in predetermined ranges. For example, a central region of movement 
of the patient support table can be selected wherein no automatic, 
oppositely directed adjustment of the imaging system occurs. When the 
patient support table is moved out of this central region, the 
aforementioned oppositely directed adjustment of the imaging system 
occurs. 
In a further modification of this embodiment, each of the ranges may have a 
speed of movement assigned thereto with the speeds changing symmetrically 
on both sides of the central region. When the patient support table is 
manually moved to a first range at one side of the central region, for 
example, the adjustment speed for the oppositely directed movement of the 
imaging system will be undertaken at a first, relatively low speed, and as 
further ranges are transgressed, i.e., as the patient support table is 
moved farther from the central region, the speed of movement of the 
oppositely directed adjustment of the imaging system is increased to a 
second, higher speed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An x-ray eXamination installation constructed in accordance with the 
principles of the present invention is shown in FIG. 1, which includes a 
C-arm 1 having opposite ends at which an x-ray source 2 and an x-ray image 
intensifier 3 are respectively mounted, with a single-frame photographic 
camera 4 and a video camera (not visible in FIG. 1) following the x-ray 
image intensifier 3. The C-arm 1 and the components mounted thereon form 
an imaging system, which is adjustable around the circumference of the 
C-arm 1 by a holder 5. The holder 5 is mounted to a carriage 7 so as to be 
pivotable around a horizontal axis 6, and the carriage 7 is seated on a 
vertical column 8 so as to be vertically adjustable. The vertical column 8 
is longitudinally displaceable, together with the carriage 7, the holder 5 
and the imaging system, along a ceiling rail 9 and a floor rail 10 
extending parallel to each other, and parallel to the longitudinal axis of 
a patient support table 11. The C-arm 1 partially surrounds the patient 
support table 11. The patient support table 11 is adjustable in height by 
means of a pedestal or base 14, on which a control panel 15 is mounted. 
The patient support table 11 can be manually adjusted in the longitudinal 
direction as indicated by arrows 16 and 17, and can also be adjusted in a 
transverse direction, perpendicular to and in the same horizontal plane 
as, the longitudinal direction. Movement of the patient support table 11 
is accomplished manually by a handle 23a. 
Adjustment of the column 8 along the rails 9 and 10 is indicated by the 
arrows 18 and 19. 
A motor 21 is provided in a base 20 of the column 8 for adjusting the 
position of the column 8 in the directions described above. The motor 21 
is driven by a motor control 22, to which a transmitter 23, contained in 
the handle 23a, is connected. The transmitter 23 supplies an electrical 
signal to the motor control 22 corresponding to the movement (direction 
and magnitude) of the patient support table 11 in the direction of the 
arrows 16 and 17. 
If the patient support table is manually displaced in the direction of the 
arrow 16, for example, the signal from the transmitted 23 causes the motor 
control 22 to operate the motor 21 so that the column 8, and the imaging 
system carried thereon, are moved in the direction of the arrow 19. If the 
patient support table 11 is adjusted in the direction of the arrow 17, an 
oppositely directed, motor-driven adjustment of the column 8, and the 
imaging system carried thereon, automatically ensues in the direction of 
the arrow 18. Adjustment of a patient lying on the patient support table 
11 with respect to the imaging system can thus be accomplished very 
quickly and simply by the automatic, oppositely directed adjustment as 
described above. 
The automatic, oppositely directed adjustment of the column 8 and the 
imaging system following adjustment of the patient support table 11 has 
been described in connection with FIG. 1 with respect to only one 
dimension. The oppositely directed adjustment can also be provided in the 
same manner in a second dimension, perpendicular to the first dimension. 
If, for example, the patient support table 11 is moved along the axis 6 in 
a direction toward the column 8, adjustment of the imaging system along 
the axis 6 away from the column can automatically ensue, and vice versa. 
For this purpose, the holder 8 can be connected to the carriage 7 by means 
of a further motor (not shown) operable to move the holder 5 along the 
axis 6. 
As described, the automatic, oppositely directed adjustment of the imaging 
system relative to the patient support table 11 ensues on the basis of the 
signal supplied by the transmitter 23 which corresponds to the direction 
of movement of the patient support table 11. It is also possible, however, 
to move the patient support table 11 by a motor, which can be manually 
controllable, in which case the transmitter 23 will provide control 
signals derived from the manual motor controls. 
A switch actuator is shown in plan view in FIG. 2, by means of which the 
total adjustment range of the patient support table 11 can be divided into 
a plurality of sub-ranges. The switch actuator can be attached to the 
accessories rail 24 of the patient support table 11, which is already 
present in most installations. The switch actuator includes a holder or 
frame 25 having a plurality, such as four, of parallel guide rods 26, 27, 
28 and 29. The guide rods have respective adjustable actuation elements 
30, 31, 32 and 33, each of which is slidable along the guide rod on which 
it is mounted in the direction of the double arrow, and once positioned on 
the guide rod, the actuation element is then made immoveable by turning a 
set screw. Each guide rod is aligned so that the actuation element thereon 
interacts with one of a plurality of limit switches 34, 35, 36 and 37. The 
frame 25 and the guide rods are positioned above the limit switches so as 
not to interact therewith; only the actuation element on each guide rod 
can actuate the limit switch aligned therewith. The limit switches 34 
through 37 are each connected to the motor control 22 and, when actuated, 
cause the motor control 22 to operate the motor 21 in a defined manner, as 
described below. 
When the patient support table 11 is adjusted within a central region, 
within which none of the limit switches 34 through 37 is actuated by an 
actuation element 30 through 33, the imaging system remains at rest, i.e., 
is not adjusted in a direction opposite to the direction of movement of 
the patient support table 11. When the central region of the patient 
support table 11 is transgressed as the patient support table 11 is moved 
to one side or the other of the central region, one of the actuation 
elements will engage its associated limit switch. In the example shown in 
FIG. 2, if the patient support table 11 were moved in the direction of the 
arrow 16, the actuation element 30 would engage the limit switch 34. If 
the patient support table 11 were moved in the opposite direction 17, the 
actuation element 33 would engage the limit switch 37. When either the 
limit switch 34 or the limit switch 37 is actuated, the motor control 22 
is activated so as to operate the motor 21 at a first, low speed, so that 
the imaging system is accordingly moved in a direction opposite to the 
direction of movement of the patient support table 11, at a relatively low 
speed. If the original direction of movement of the patient support table 
11 were in the direction of the arrow 16, and if movement of the patient 
support table 11 in that direction were continued, the actuation element 
31 would subsequently engage the limit switch 35. Similarly, if the 
original direction of movement of the patient support table 11 had been in 
the direction of the arrow 17, and if movement of the patient support 
table 11 in this direction were continued, the actuation element 32 would 
engage the limit switch 36. If either of the limit switches 35 or 36 is 
actuated, the motor control 22 is caused to operate the motor 21 at a 
second, higher speed. This results in the imaging system being moved in a 
direction opposite to the direction of movement of the patient support 
table 11 at a speed which is higher than the speed with which the imaging 
system was moved when the patient support table 11 was in the regions 
immediately adjacent the central region. 
The overall range of movement of the patient support table 11 is thus 
sub-divided into five regions, a central region with two regions on each 
side thereof, with each region beyond the central region having a limit 
switch and an actuation element associated therewith. The size of each of 
the regions can be set by positioning the respective actuation elements 30 
through 33 along the guide rods 26 through 29. If movement of the patient 
support table 11 takes place within the central region, no following 
movement of the imaging system occurs. If the patient support table 11 is 
moved in either direction from the central region into one of the 
immediately adjacent regions, the imaging system will be moved in the 
opposite direction at a low speed. If movement of the patient support 
table 11 continues beyond the immediately adjacent regions, the oppositely 
directed movement of the imaging system takes place at a higher speed. 
Although modifications and changes may be suggested by those skilled in the 
art, it is the intention of the inventors to embody within the patent 
warranted hereon all changes and modifications as reasonably and properly 
come within the scope of their contribution to the art.