U.S. patent number 3,757,129 [Application Number 05/309,006] was granted by the patent office on 1973-09-04 for x-ray table patient rotator basket.
Invention is credited to William F. Hogan.
United States Patent |
3,757,129 |
Hogan |
September 4, 1973 |
X-RAY TABLE PATIENT ROTATOR BASKET
Abstract
A basket for receiving a patient for full-length X-ray
examination is movable laterally relative to the X-ray table. The
basket is also rotatable on its own longitudinal axis, and when so
rotated the level or elevational position of the basket is adjusted
automatically.
Inventors: |
Hogan; William F. (Woodbury,
NJ) |
Family
ID: |
23196264 |
Appl.
No.: |
05/309,006 |
Filed: |
November 24, 1972 |
Current U.S.
Class: |
5/601; 5/607;
378/209 |
Current CPC
Class: |
A61B
6/0487 (20200801); A61B 6/0428 (20130101) |
Current International
Class: |
A61B
6/04 (20060101); G03b 041/16 () |
Field of
Search: |
;250/55,56,57
;269/323 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Church; C. E.
Claims
What is claimed is:
1. Apparatus for supporting a patient for X-ray examination, said
apparatus comprising:
a. An X-ray table top having a panel at each end;
b. Support means for said table top;
c. Main carriage means for each end and means for mounting said
carriage means for transverse movement on each of said table top
end panels;
d. A basket for receiving a patient, said basket having a panel at
each end;
e. First cam means secured to each of said carriages;
f. Second cam means secured to each of the end panels of said
basket and operatively engaging said first cam means for supporting
said basket thereon;
g. Shaft means on the longitudinal axis of said basket at each end
and secured to said basket end panels;
h. Means journalling said basket shaft means in said carriage means
at each end;
i. Drive means, including means at each end and interconnecting
means therebetween, for rotating said basket shaft means, said
basket and basket shaft means during such rotation being adjusted
vertically by the cooperative action of Said first and second cam
means; and
j. Drive means, including means at each end and interconnecting
means therebetween, for moving said carriage means transversely to
move said basket laterally relative to said table top while
automatically adjusting the basket shaft drive means at each end to
accommodate to driving said basket shaft means in its new
transverse location.
2. Apparatus according to claim 1 wherein said means for moving
said carriage means transversely comprises:
a. Elongated screw means at each end supported on said table top
end panels;
b. Nut means at each end mounted on said elongated screw means,
c. Means at each end connecting said nut means to said carriage
means; and
d. Power means at one end only for driving said screw means at each
end rotationally, said screw means at the other end being driven by
said interconnecting means.
3. Apparatus according to claim 1 wherein said means journalling
said basket shaft means in said carriage means comprises:
a. A sub-carriage and means supporting said sub-carriage for
vertical movement within said main carriage means.
4. Apparatus according to claim 3 wherein said drive means for
rotating said basket about the axis of said basket shaft means
comprises:
a. A gear mounted on and secured to said basket shaft means at one
end of said basket;
b. Gear drive means mounted on said sub-carriage and in mesh with
said gear;
c. Motor means mounted on said sub-carriage for driving said gear
drive means;
d. An interconnecting shaft extending from one end of said table
top to the other;
e. A series chain-and-sprocket means at each end of said table top,
the sprocket means at one end of the series being mounted on a
shaft fixed in said main carriage means, the sprocket means at the
other end of the series being mounted on a shaft having a fixed
position in said table top;
f. A pair of rigid arms having their adjacent ends pivotallY
mounted together on a common movable shaft, the distal end of one
of said arms being pivotally mounted on said fixed shaft of said
sprocket means at one end of said series, the distal end of the
other of said arms being pivotally mounted on said fixed shaft of
the sprocket means at the other end of the series, intermediate
sprocket means being mounted on said common movable shaft, and
g. Means connecting said sprocket means at said other end of said
series to said interconnecting shaft.
5. Apparatus according to claim 4 wherein:
a. Said means connecting said sprocket means at said other end of
said series to said interconnPcting means comprises an additional
sprocket mounted on and secured to said interconnecting shaft and a
chain connecting said additional sprocket to said other end
sprocket.
6. Apparatus according to claim 1 wherein:
a. said end panels of said table top are slotted;
b. Said first cam means comprises a cam shaft mounted in said main
carriage and projecting through a slot in said table top end
panel;
c. A cam bearing is mounted for rotation on said cam shaft;
d. Said second cam means comprises a contoured cam plate which
bears on said cam bearing to support said basket, whereby rotation
of said basket shaft means causes said basket and cam plate to
rotate, whereby said cam plate and cam bearing cooperate to change
the elevational position of said basket shafts.
7. Apparatus according to claim 6 wherein:
a. Said cam plate is so contoured as to maintain the exterior
surface of a patient in the basket at a substantially constant
distance above the table top during rotation of said basket.
8. Apparatus according to claim 1 wherein said means for mounting
said carriage means for transverse movement on said table top end
panel includes bearing rails secured to said end panel.
9. Apparatus according to claim 8 wherein:
a. Said bearing rails are formed of surface-hardened aluminum.
10. Apparatus according to claim 9 wherein:
a. Said surface-hardened aluminum bearing rails are Tufram
treated.
11. Apparatus according to claim 3 wherein said means for rotating
said basket about the axis of said basket shaft means
comprises:
a. A worm gear mounted on and secured to said basket shaft
means;
b. A worm mounted on said sub-carriage and in mesh with said worm
gear; and
c. Motor means mounted on said sub-carriage for driving said worm
shaft.
12. Apparatus according to claim 11 wherein said means for rotating
said basket also includes:
a. An interconnecting shaft extending from one end of said table
top to the other;
b. A series chain-and-sprocket means at each end of said table top,
the sprocket means at one end of the series being mounted on a
shaft fixed in said main carriage means, the sprocket means at the
other end of the series being mounted on a shaft having a fixed
position in said table top;
c. A pair of rigid arms having their adjacent ends pivotally
mounted together on a common movable shaft, the distal end of one
of said arms being pivotally mounted on said fixed shaft of said
sprocket means at one end of said series, the distal end of the
other of said arms being pivotally mounted on said fixed shaft of
the sprocket means at the other end of the series, intermediate
sprocket means being mounted on said common movable shaft, and
d. Means connecting said sprocket means at said other end of said
series to said interconnecting shaft.
13. Apparatus according to claim 12 wherein:
a. Said means connecting said sprocket means at said other end of
said series to said interconnecting means comprises an additional
sprocket mounted on and secured to said interconnecting shaft and a
chain connecting said additional sprocket to said other end
sprocket.
14. Apparatus according to claim 13 wherein:
a. Said end panels of said table top are slotted;
b. Said first cam means comprises a cam shaft mounted in said main
carriage and projecting through a slot in said table top end
panel;
c. A cam bearing is mounted for rotation on said cam shaft; and
d. Said second cam means comprises a contoured cam plate which
bears on said cam bearing to support said basket, whereby rotation
of said basket shaft means causes said basket and cam plate to
rotate, whereby said cam plate and cam bearing cooperate to change
the elevational position of said basket shafts.
15. Apparatus according to claim 14 wherein:
a. Said cam plate is so contoured as to maintain the exterior
surface of a patient in the basket at a substantially constant
distance above the table top during rotation of said basket.
16. Apparatus according to claim 15 wherein said means for mounting
said carriage means for transverse movement on said table top end
panel includes bearing rails secured to said end panel.
17. Apparatus according to claim 16 wherein:
a. Said bearing rails are formed of surface-hardened aluminum.
Description
BACKGROUND OF THE INVENTION
This invention relates to an X-ray table top having a cradle or
basket in which the patient is strapped in full-length on-the-back
position for X-ray examination.
The invention relates particularly to means for moving the basket
laterally relative to the table top, and for also rotating the
basket about its longitudinal axis, and for means for adjusting
automatically the level or elevational position of the basket when
the basket is rotated.
In the X-ray examination of patients, it is desirable that the
basket in which the patient is strapped be movable universally so
that the patient may be presented to the X-rays in a variety of
desired positions. The basket is rotatable about its longitudinal
axis, relative to the supporting table top, so as to present the
front, or back, or any side portion of the patient to the
X-rays.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide a
patient-receiving basket for an X-ray table wherein the basket is
movable in the lateral or transverse direction relative to the
table top, as well as being movable rotatably about its own
longitudinal axis by means which automatically adjust the level or
elevational position of the basket so as to maintain the patient on
a constant level relative to a fixed X-ray image plane.
The foregoing object, as well as other objects of the invention,
are achieved by the following means:
The end panels of the X-ray table top, that is, the head panel and
the foot panel, are provided with horizontal slots through which a
cam-follower shaft extends at each end. Each cam-follower shaft is
supported in a carriage that is movable in the transverse or
lateral directions relative to the X-ray table top. This carriage
is movably supported on tracks secured to the end panel of the
table top. The inward end of the cam-follower shaft carries a
cam-follower roller bearing which supports a cam plate secured to
the end panel of the patient rotator basket. Thus, the basket is
supported at each end on the cam-follower roller bearing which in
turn is supported in the transversely movable carriage. Extending
outwardly from each end plate of the basket is a trunnion or shaft
which extends through a horizontal slot in the end panel of the
table top and is journalled in a sub-carriage which is carried by,
and movable vertically on tracks within, the main transversely
movable carriage. Power means are provided for driving the basket
shafts rotationally at both ends to rotate the basket to the
desired angular position up to full 90.degree. in either direction.
When the basket is so rotated, the cam plate at each end of the
basket rotates therewith on the cam-follower bearing and is of such
a shape as to cause the basket shafts to change level or
elevational position relative to the X-ray table top and relative
to the X-ray image plane so as to retain the patient at a constant
level. When the basket shaft is raised or lowered vertically, it
raises or lowers the sub-carriage in which the shaft is journalled.
Power means are also provided for moving both ends of the main
carriage transversely relative to the X-ray table top. Such means
include a nut connected to the main carriage and adapted to travel
along an elongated laterally disposed screw supported on the end
panel of the table top. When the main carriage is driven laterally
by the nut, the basket shafts are carried along therewith, and in
so doing move the basket laterally relative to the table top.
Separate drive means are provided for moving the basket
rotationally and for driving the basket laterally. Similar and
corresponding drive means are provided at each end of the table
top, with the exception that the power or motor means are provided
only at one end, preferably at the foot end. Elongated shafts
extend the full length of the table top and connect the
motor-driven drive means at the foot end with corresponding means
at the head end. The basket may be rotated while occupying any of
the lateral positions. The drive means for driving the basket
rotationally includes, at each end of the table top, a pair of
rigid pivotal link arms which support and carry the sprockets of a
chain-and-sprocket system which is used to transfer the
power-driven drive of the basket shaft at one end of the table top
to the basket shaft at the other end.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic plan view of an X-ray table top on which is
supported a patient-receiving basket, which, in accordance with the
present invention, is movable transversely relative to the X-ray
table top, as well as being adjustably rotational on its own
longitudinal axis.
FIG. 2 is an elevational end view of the foot end of the table top
looking along the line 2--2 of FIG. 1.
FIG. 3 is an elevational end view of the head end of the table top
looking along the line 3--3 of FIG. 1.
FIG. 4 is a view, in section, at the foot end of the table top
looking along the line 4--4 of FIG. 2.
FIG. 5 is a plan view, at the head end of the table top, looking
down along the line 5--5 of FIG. 3.
FIG. 6 is a view, in section, looking down along the line 6--6 of
FIG. 4.
FIG. 7 is a schematic end view of the basket end panel illustrating
its rotational movement supported by the cam plate on the cam
follower roller bearing.
FIG. 8 is a fragmentary view showing the basket cam plate in a
limit position on the cam-follower roller bearing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, FIG. 1 is a plan view of an X-ray
table top 20 having supported thereon a cradle or basket 30. The
means for supporting the X-ray table top 20 is not shown but may
comprise pedestal elevator means located under the center portion
of the table top 20 and on which the table top 20 may be shifted
longitudinally and transversely raised, lowered, or pivoted about
its short transverse center axis. In FIG. 1, reference numeral 40
identifies the foot end of the table top while numeral 140
identifies the head end.
A source of X-rays not shown in the drawings is positioned above or
below the table top to project X-rays down or up through the table
top onto an image plane, not shown, located below or above the
table top. The image plane may be an image amplifier, or a
photographic film, or any other suitable image-forming device.
Thus, the table top is disposed between the source of X-rays, which
ordinarily includes a collimator, and the image plane.
The patient to be X-rayed is ordinarily strapped in the basket 30
in full length on-the-back position. The basket 30 is made of
material, such as rigid plexiglass, which is transparent to X-rays.
The basket 30 is shown in FIG. 7 as having straight sides and a
concave bottom.
The basket 30 is rotatable about a pair of trunnions 31 and 131
which extend outwardly, along the projected longitudinal axis of
the basket, from the foot and head panels 32 and 132, respectively,
of the basket. As seen in FIG. 7, the patient basket 30 is
substantially wider than it is deep and, accordingly, unless
compensating provision is made, when the basket 30 is rotated about
its shafts 31 and 131 the distance between the nearest boundary of
the basket and the X-ray image plane changes, becoming shorter as
the basket is rotated from the solid-line position shown in FIG. 7,
in which the patient is lying on his back, to the phantom positions
shown in FIG. 7 in which the patient is lying on his side.
Heretofore, in the prior art, means have been provided for
automatically adjusting the height or elevational position of the
rotational axis of the basket 30 as the basket is rotated on its
shafts 31 and 131. Such prior art means are shown in U. S. Pat. No.
3,482,094 issued to William J. Hogan on Dec. 2, 1969. In that
patent, a flat horizontal cam rail is fixed to the foot and head
end panels of the X-ray table top, and the basket is supported
thereon by means of a series of cam follower rollers secured to the
end panels of the basket along selected cam paths. When the basket
is rotated these cam rollers go into and out of engagement with the
flat cam surface and the basket shafts are caused to move upwardly
or downwardly, as the case may be. The cam rollers in the patent
are at spaced intervals along the cam path and, as a result, the
transfer of the weight of the patient-occupied basket from one cam
roller to another is noticeable to the patient, which is
undesirable. This undesirable feature is not present in the
rotational mechanism provided by the present application wherein
the shape of the cam allows for a true and constant patient plane
during rotation. In addition, the basket of the present application
is also movable in the transverse or lateral direction, so that the
patient may be placed in the most desirable position for X-ray
examination.
FIG. 2 is an elevational end view of the mechanism at the foot end
40 of the X-ray table top while FIG. 3 is an elevational end view
of the mechanism at the head end 140 of the table top. The
mechanisms at the foot and head ends are similar with corresponding
components. However, motor power is provided at one end only, the
foot end, with drive shafts extending the full length of the table
for driving the mechanism at the head end. This has the advantage
of reducing the bulk of the equipment at the head end, thereby
making space available for closer examination of the patient at the
head and upper regions of the patient's body. Another advantage is
that by having the motors at the foot end the weight at each end of
the table top tends to be more nearly balanced, since the major
portion of the total weight of the patient is on the head side of
the transverse center line of the table top.
FIG. 4 is an elevational view, in section, at the foot end of the
table top, as seen looking along the line 4--4 of FIG. 2. FIG. 5 is
a plan view at the head end of the table top looking down along the
line 5--5 of FIG. 3.
Referring now to FIGS. 1-5, a first drive motor 41 is supported, as
by brackets 42 and 61, on a sub-carriage 45 mounted for vertical
movement within a transversely movable main carriage 43 which is
supported on bearing rails secured to the foot panel 44 of the
X-ray table top. The function of motor 41 is to rotate basket 30
about the vertically-movable axis of rotation of the basket. A
second motor 81 is provided, supported in fixed position on the
foot panel 44 of the table top, for moving the basket 30 laterally
relative to the table top.
It was indicated previously that except for the motors, the drive
mechanisms at the two ends of the table top are similar, and
accordingly, it will only be necessary to describe in detail the
mechanism at one end. Corresponding parts at the other end are
identified by similar reference numerals to which 100 has been
added. For example, the transverse screw at the foot end is 85,
while the transverse screw at the head end is 185. The provision of
corresponding drive mechanisms at both ends is desirable, as
compared with driving the basket rotationally and/or transversely
from one end only, in that undesirable torsional and/or lateral
strain on the basket is avoided.
The manner in which the basket 30 is supported will first be
described, after which there will be a description of the mechanism
for moving the basket laterally relative to the X-ray table top,
followed by a description of the means for rotating the basket and
for automatically adjusting the level of the basket axis during
rotation.
Reference numerals 32 and 132 identify the foot and head panels,
respectively, of the basket 30. Secured to each end panel of the
basket is a trunnion or shaft, 31 and 131, respectively, for the
foot and head ends. These shafts 31 and 131 are shown to be secured
by their flange portions 33 and 133. Each of the basket shafts 31
and 131 has several reduced-diameter portions, as seen in FIG. 4,
forming shoulders against which bearings or other parts may
abut.
Also secured to each end panel 1 and 132 of the basket 30 is a cam
plate, 34 and 134, respectively, whose cam surfaces may have a
contour such as is seen in FIG. 7. These cam plates 34 and 134 rest
on cam-follower roller bearings, 35 and 135, respectively. The
bearings 35 and 135 are rotatably supported on shafts, 36 and 136,
respectively, which are secured in, and supported by, main carriage
43 and 143 respectively. By a mechanism to be described below, main
carriages 43 and 143, at the foot and head ends respectively, are
movably supported on the end panels 44 and 144 of the X-ray table
top for transverse movement relative thereto.
The mechanism for moving the basket 30 laterally relative to the
table top will now be described, after which the mechanism for
rotating the basket 30 on its own long axis will be described.
The motor 81 for driving the basket 30 in the transverse or lateral
direction is seen in FIG. 2. Motor 81, which is mounted on the foot
panel 44 of the X-ray table top, drives, through a gear-reducing
unit 82, a shaft 89 having at one end a miter gear 83 which is in
mesh with a miter gear 84 secured to one end of a transverse screw
85. Screw 85 is supported by blocks 86 on the foot panel 44 and
occupies a position parallel to the foot panel. Shaft 89, driven by
the motor 81 through gear reducer 82, is a long shaft which extends
the full length of the table top within the side rail 21. A miter
gear 183 at the head end of the shaft 89 meshes with miter gear 184
on the transverse screw 185, as seen in FIG. 3. Thus, when motor 81
drives screw 85 at the foot end, screw 185 at the head end is also
driven. Motor 81 may desirably be provided with a magnetic brake so
that when the power to the motor 81 is shut off, lateral movement
of the basket stops. The miter gears 83, 84, 183 and 184 are
preferably fiber gears in order to avoid the noise which metal
gears would generate and which may be bothersome to the
patient.
Mounted on screw 85 at the foot end is a nut 87, preferably a ball
nut, and a corresponding nut 187 is mounted on screw 185 at the
head end. The nuts 87 and 187 are connected by brackets 88 and 188,
respectively, to the transverse carriages 43 and 143 at the foot
and head ends, respectively. These carriages, one at each end of
the table top, are supported in tracks secured, as by bolts, to the
foot and head panels 44 and 144 of the X-ray table top. The tracks
comprise an upper set of bearing rails 51 and a lower set of
bearing rails 52 secured to the foot panel 44 and corresponding
sets of bearing rails secured to the head panel 144. Along these
rails run the upper bearings 53, 54 and the lower bearings 55, 56
of the transverse carriage 43. Bearings 53 and 55 are lateral
bearings which bear laterally against the rails 51 and 52 while
bearings 54 and 56 are vertical bearings which bear vertically
thereagainst.
The main carriage 43 carries a sub-carriage 45 which is adapted to
move up and down on a vertical track within the main carriage 43.
This track is comprised of vertical rails 46 and 47 secured to and
carried by the main carriage 43. Against these vertical rails bear
the upper and lower sets of roller bearings 48 and 49 of the
vertically movable sub-carriage 45. Journalled in the sub-carriage
45, as by bearings 57 (FIG. 4), is the shaft 31 of the basket 30.
Thus, when the main carriage 43 is moved laterally by the screw 85
and nut 87, the basket shift 31, and hence the basket 30, are
carried laterally therewith. Simultaneously, at the other end of
the table top, the basket shaft 131 is being carried laterally by
the carriage 143.
The mechanism for rotating the basket 30 on its shafts 31 and 131
will now be described. During rotation, the basket 30 remains
supported by cam plates 34 and 134 secured to the end panels 32 and
132 of the basket, and by the cam-follower bearings 35 and 135
which are supported in the main carriages 43 and 143. As has been
described, the basket shafts 31 and 131 project through slots in
the end panels 44 and 144 of the table tops and are journalled in
the sub-carriages 45 and 145. Secured to sub-carriages 45 and 145,
as seen in FIG. 4, is a support bracket 61 and 161, respectively,
in which basket shafts 31 and 131, are additionally journalled, as
in bearings 62, seen in FIG. 4.
Mounted on basket shafts 31 and 131 are sprockets 63 and 163,
respectively, about which chains 64 and 164 are respectively
trained.
Mounted on, and secured to basket shaft 31 at the foot end of the
table top (but omitted from basket shaft 131 at the head end) is a
worm gear 65 which is in mesh with and driven by a worm 66 (FIG. 2)
which is driven by drive motor 41 through a gear reducing unit 67.
Thus, when the motor 41 is energized, under the control of a
suitably mounted switch or switches, the worm gear 65 is driven
rotationally thereby rotating the basket shaft 31. WYen basket
shaft 31 is thus rotated, sprocket 63, which is keyed, pinned, or
otherwise secured to the shaft 31, is rotated. Sprocket 63 drives a
series of chains and sprockets, as well as suitable idler sprockets
(not shown) for tension control. This series of chains and
sprockets is identified comprehensively by reference numeral 70.
The final sprocket of the series is identified 71. Sprocket 71 is
keyed or otherwise secured to an elongated shaft 72 which extends
the full length of the table top within the side rail 22. Thus,
when motor 41 is energized, sprocket 71 drives the shaft 72
rotationally. For convenience, motor 41 is under the control of two
switches, one at each end of the X-ray table top.
At the head end of shaft 72, as seen in the lower corner portion of
FIG. 3, a sprocket 171 is keyed which, through a series of chains
and sprockets 170 corresponding to those identified as 70 at the
foot end of the table, drives sprocket 163 which is secured to
basket shaft 131. Thus, basket shaft 131 is driven rotationally at
the same time, in the same direction, and to the same extent, that
the basket shaft 31 at the foot end is driven rotationally by the
motor 41.
The chain-and-sprocket system 70 at the one end of the table top,
and the corresponding chain-and-sprocket system 170 at the other
end of the table top is specially adapted to accommodate to the
fact that the basket is movable laterally relative to the table
top. To this end, the chain-and-sprocket system includes a pair of
rigid pivotal link arms 96 and 97 at the foot end with
corresponding rigid link arms 196 and 197 at the head end. Looking
at FIG. 2, it will be seen that the lower end of arm 96 is
pivotally supported on shaft 78 mounted for rotation in support
block 77. Shaft 78 carries the dual sprockets 75. The lower or
inward end of arm 97 is pivotally supported on shaft 80 mounted on
an extension 98 of the main carriage 43. The other ends of arms 96
and 97 are pivotally connected on common shaft 79 which is free to
move. It will be seen that when the carriage 43 is driven to the
left, as viewed in FIG. 2, shaft 80 travels along a horizontal
straight path, while shaft 79 is pushed leftward along an arcuate
path. In this movement the dual sprockets 73 do not rotate, and the
chain 76 merely walks around the sprocket 74. Thus, the mechanism
shown accommodates to the translational or lateral movement of the
basket without causing rotation of the basket about the basket
shafts. Rotation of basket 30 about the basket shafts only occurs
when motor 41 is energized to drive the basket shaft 31
rotationally through worm 66 and worm gear 65. This driving of
basket shaft 31 is transmitted through the chain-and-sprocket
sYstems to the basket shaft 131 at the other end.
To prevent the basket 30 from being rotated beyond desired limits,
electrical, and also mechanical, limiting devices may preferably be
provided. In the drawings, worm gear 65 is shown as having keyed
thereto a sector plate 92 having fixed thereto and projecting
outwardly therefrom a limit pin 93 which is adapted to contact one
or the other of a pair of limit switches 94, 95 to shut off the
drive motor 41. One of the limit switches 94 projects against
excessive rotation of the basket shaft and basket in the
counter-clockwise direction (FIG. 2) while the other limit switch
95 projects against excessive rotation in the clockwise
direction.
Mechanical protection against rotating the basket beyond desired
limits is also provided, as seen in FIGS. 7 and 8, by affixing a
pair of limit pins 37 to the end panel 32 of the basket 30. Similar
limit screws 137 (FIG. 5) may also be provided in the panel 132 at
the other end of the basket. It will be seen from the schematic
illustration in FIGS. 7 and 8 that when the basket has been
rotated, either clockwise or counterclockwise, to the positions
shown in phantom in FIG. 7, the stop pin 37 comes into contact with
the bearing 35 to prevent further rotation of the basket. This
assures that the basket is not rotated beyond the point where the
cam plate 34 supports the basket on the bearing 35.
At least some of the component parts of the mechanism illustrated
and described herein may be formed of lightweight metal in order to
reduce the weight and/or cost of the equipment. For example, the
bearing rails 51 and 52 for the transversely movable main carriage
43, and the bearing rails 46, 47 for the vertically movable
sub-carriage 45, may preferably be formed of aluminum having a
hardened surface, hardened, for example, by the Tufram process, a
process of General Magnaplate Corporation of Linden, N.J. When
applied to aluminum, the Tufram process produces a surface as hard
as hardened steel, as well as a permanently dry lubricating
surface.
Attention is called to the contour of the continuous cam surface of
the cam plate 34, clearly seen in FIG. 7. This contour is specially
designed to keep the exterior surface of the patient at a constant
level, relative to the X-ray plane located beneath the X-ray table
top, as the basket is rotated to different angular positions.
The apparatus shown and described has several features which
perhaps should be summarized:
First, the basket is driven from both ends. This is highly
desirable and is necessary to avoid the torsional stress and
twisting of the basket which would occur were it to be driven only
from one end.
Secondly, the basket is driven both rotationally and laterally. To
accomplish this, and driven at both ends, the pivotal-arm
sprocket-and-chain system shown and described is provided. This is
an important part of the apparatus.
Lastly, the basket is supported by a continuous cam having a shape
or contour specially designed to keep the exterior surface of the
patient at a constant level relative to the X-ray image plane
beneath the X-ray table.
* * * * *