Patient support for a scintillation camera

A patient support is designed for use with a scintillation camera that includes a vertically oriented annular rotating support having an axis, and an elongate support extending from the rotating support for supporting a detector head, the rotating support including a coaxial inner surface defining an orifice. The patient support includes a patient stretcher for supporting a patient in a horizontal position substantially parallel to the axis of the rotating support. The patient support also includes a detached support for horizontally supporting the patient stretcher on a ground surface. The detached support includes a first stretcher support for supporting the patient stretcher and for positioning the patient stretcher relative to the rotating support. The patient support also includes an engaged support for horizontally supporting the patient stretcher on the inner surface of the cylindrical support such that the patient stretcher remains unaffected by the rotation of the rotating support. The engaged support includes a second stretcher support for supporting the patient stretcher and for positioning the patient stretcher relative to the rotating support.

FIELD OF INVENTION 
The present invention relates to a patient support for a scintillation 
camera. In particular, the invention relates to an apparatus for 
supporting a patient and for positioning a patient relative to a 
scintillation camera including a gantry having a rotating annular support. 
BACKGROUND OF THE INVENTION 
In the human body, increased metabolic activity is associated with an 
increase in emitted radiation. In the field of nuclear medicine, increased 
metabolic activity within a patient is detected using a radiation detector 
such as a scintillation camera. 
Scintillation cameras are well known in the art, and are used for medical 
diagnostics. A patient ingests, or inhales or is injected with a small 
quantity of a radioactive isotope. The radioactive isotope emits photons 
that are detected by a scintillation medium in the scintillation camera. 
The scintillation medium is commonly a sodium iodide crystal, BGO or 
other. The scintillation medium emits a small flash or scintillation of 
light, in response to stimulating radiation, such as from a patient. The 
intensity of the scintillation of light is proportional to the energy of 
the stimulating photon, such as a gamma photon. Note that the relationship 
between the intensity of the scintillation of light and the gamma photon 
is not linear. 
A conventional scintillation camera such as a gamma camera includes a 
detector which converts into electrical signals gamma rays emitted from a 
patient after radioisotope has been administered to the patient. The 
detector includes a scintillator and photomultiplier tubes. The gamma rays 
are directed to the scintillator which absorbs the radiation and produces, 
in response, a very small flash of light. An array of photodetectors, 
which are placed in optical communication with the scintillation crystal, 
converts these flashes into electrical signals which are subsequently 
processed. The processing enables the camera to produce an image of the 
distribution of the radioisotope within the patient. 
Gamma radiation is emitted in all directions and it is necessary to 
collimate the radiation before the radiation impinges on the crystal 
scintillator. This is accomplished by a collimator which is a sheet of 
absorbing material, usually lead, perforated by relatively narrow 
channels. The collimator is detachably secured to the detector head, 
allowing the collimator to be changed to enable the detector head to be 
used with the different energies of isotope to suit particular 
characteristics of the patient study. A collimator may vary considerably 
in weight to match the isotope or study type. 
Scintillation cameras are used to take four basic types of pictures: spot 
views, whole body views, partial whole body views, SPECT views, and whole 
body SPECT views. 
A spot view is an image of a part of a patient. The area of the spot view 
is less than or equal to the size of the field of view of the gamma 
camera. In order to be able to achieve a full range of spot views, a gamma 
camera must be positionable at any location relative to a patient. 
One type of whole body view is a series of spot views fitted together such 
that the whole body of the patient may be viewed at one time. Another type 
of whole body view is a continuous scan of the whole body of the patient. 
A partial whole body view is simply a whole body view that covers only 
part of the body of the patient. In order to be able to achieve a whole 
body view, a gamma camera must be positionable at any location relative to 
a patient in an automated sequence of views. 
The acronym "SPECT" stands for single photon emission computerized 
tomography. A SPECT view is a series of slice-like images of the patient. 
The slice-like images are often, but not necessarily, transversely 
oriented with respect to the patient. Each slice-like image is made up of 
multiple views taken at different angles around the patient, the data from 
the various views being combined to form the slice-like image. In order to 
be able to achieve a SPECT view, a scintillation camera must be rotatable 
around a patient, with the direction of the detector head of the 
scintillation camera pointing in a series of known and precise directions 
such that reprojection of the data can be accurately undertaken. 
A whole body SPECT view is a series of parallel slice-like transverse 
images of a patient. Typically, a whole body SPECT view consists of sixty 
four spaced apart SPECT views. A whole body SPECT view results from the 
simultaneous generation of whole body and SPECT image data. In order to be 
able to achieve a whole body SPECT view, a scintillation camera must be 
rotatable around a patient, with the direction of the detector head of the 
scintillation camera pointing in a series of known and precise directions 
such that reprojection of the data can be accurately undertaken. 
Therefore, in order that the radiation detector be capable of achieving the 
above four basic views, the support structure for the radiation detector 
must be capable of positioning the radiation detector in any position 
relative to the patient. Furthermore, the support structure must be 
capable of moving the radiation detector relative to the patient in a 
controlled manner along any path. 
In order to operate a scintillation camera as described above, the patient 
should be supported horizontally on a patient support or stretcher. 
The detector head of the scintillation camera must be able to pass 
underneath the patient. Therefore, in order for the scintillation camera 
to generate images from underneath the patient, the patient support must 
be thin. However, detector heads are generally supported by a pair of arms 
which extend from a gantry. Thus, the patient support generally must be 
cantilevered in order for the detector head to be able to pass underneath 
the patient without contacting any supporting structure associated with 
the patient support. The design of a cantilevered patient support that is 
thin enough to work properly with a scintillation camera is exceedingly 
difficult. Expensive materials and materials that are difficult to work 
with, such as carbon fiber, are often used in the design of such 
cantilevered patient supports. 
A certain design of gantry or support structure for a scintillation camera 
includes a frame upon which a vertically oriented annular support rotates. 
Extending out from the rotating support is an elongate support. The 
elongate support generally comprises a pair of arms. The pair of arms 
generally extends through a corresponding pair of apertures in the 
rotating support. One end of the pair of arms supports the detector head 
on one side of the annular support. The other end of the pair of arms 
supports a counter balance weight. Thus, the elongate support is 
counterbalanced with a counterweight on the opposite side of the detector 
head. 
With such a design of support structure for a scintillation camera, a 
patient must lie on a horizontally oriented patient support. The patient 
support must be cantilevered so that the detector head can pass underneath 
the patient. If the detector head must pass underneath only one end of the 
patient, such as the patient's head, the cantilevered portion of the 
patient support is not long enough to cause serious difficulties in the 
design of the cantilevered patient support. However, if the camera must be 
able to pass under the entire length of the patient, the entire patient 
must be supported by the cantilevered portion of the patient support. As 
the cantilevered portion of the patient support must be thin so as not to 
interfere with the generation of images by the scintillation camera, 
serious design difficulties are encountered. 
Among the advantages associated with such design of support structure is 
that a patient may be partially passed through the orifice defined by the 
annular support so that the pair of arms need not be as long. However, the 
patient support must be able to support the patient in this position 
relative to the annular support, must be accurately positionable relative 
to the annular support, and must not interfere either with the rotation of 
the annular support or with the cables which will inevitably extend from 
the detector head to a nearby computer or other user control. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an improved patient 
support for a scintillation camera. 
A second object of the present invention is to provide an improved patient 
support for use with a scintillation camera including a rotatable annular 
support for supporting and positioning a detector head. 
The patient support of the present invention is designed for use with a 
scintillation camera that includes a vertically oriented annular rotating 
support having an axis, and an elongate support extending from the 
rotating support for supporting a detector head, the rotating support 
including a coaxial inner surface defining an orifice. 
A patient support embodying the present invention includes a patient 
stretcher for supporting a patient in a horizontal position substantially 
parallel to the axis of the rotating support. 
The patient support embodying the present invention also includes a 
detached support for horizontally supporting the patient stretcher on a 
ground surface. The detached support includes a first stretcher support 
for supporting the patient stretcher and for positioning the patient 
stretcher relative to the rotating support. 
The patient support embodying the present invention also includes an 
engaged support for horizontally supporting the patient stretcher on the 
inner surface of the cylindrical support such that the patient stretcher 
remains unaffected by the rotation of the rotating support. The engaged 
support includes a second stretcher support for supporting the patient 
stretcher and for positioning the patient stretcher relative to the 
rotating support. 
In an embodiment of the patient support of the present invention, the 
patient support includes a cylindrical support rigidly mountable to the 
inner surface of a rotating support. The cylindrical support is coaxial 
with and extends beyond the rotating support. The cylindrical support 
includes an inner surface, an outer surface, a circular front edge, and a 
circular rear edge. 
The embodiment also includes a patient stretcher for supporting a patient 
in a horizontal position substantially parallel to the axis of the 
rotating support. The patient stretcher includes a flat lower surface and 
two parallel sides 
The embodiment also includes a detached support for horizontally supporting 
the patient stretcher on a ground surface. The detached support includes a 
first rigid frame. The detached support also includes floor rolling means 
for engaging a ground surface such that the first rigid frame is moveable 
relative to the ground surface. The floor rolling means includes a 
plurality of casters. The detached support also includes a brake for 
immobilizing the frame relative to the ground surface. The brake includes 
a plurality of extendable and retractable feet for selectively engaging 
the ground surface. The detached support also includes a first stretcher 
support for supporting the patient stretcher and for positioning the 
patient stretcher relative to the rotating support. The first stretcher 
support includes a plurality of parallel wheels in rolling engagement with 
the lower surface of the patient support. The first stretcher support also 
includes a pair of rails slidably engaging the sides of the patient 
support for horizontally stabilizing the patient support. 
The embodiment also includes an engaged support for horizontally supporting 
the patient stretcher on the inner surface of the cylindrical support such 
that the patient stretcher remains unaffected by the rotation of the 
rotating support. The engaged support includes a second rigid frame. The 
engaged support also includes a transverse rolling means for engaging the 
inner surface of the rotating support. The transverse rolling means 
includes a plurality of parallel wheels for orienting perpendicularly to 
the axis of the rotating support in rolling engagement with the inner 
surface of the cylindrical support. The engaged support also includes a 
second stretcher support for supporting the patient stretcher and for 
positioning the patient stretcher relative to the rotating support. The 
second stretcher support includes a plurality of parallel wheels for 
rolling engagement with the lower surface of the patient support. The 
engaged support also includes a stabilizer for stabilizing the engaged 
support relative to the cylindrical support. The stabilizer also includes 
at least one wheel in rolling engagement with the outer surface of the 
cylindrical support. The stabilizer also includes at least one wheel in 
rolling engagement with the front edge of the cylindrical support. The 
stabilizer also includes at least one wheel in rolling engagement with the 
rear edge of the cylindrical support. 
One advantage of the present invention is that there is provided an 
improved patient support for a scintillation camera. A second advantage is 
that there is provided an improved patient support for use with a 
scintillation camera including a rotatable annular support for supporting 
and positioning a detector head. A third advantage is that the patient 
stretcher need not be cantilevered to an extent that causes design 
difficulties. A fourth advantage is that the patient support can be thin 
so as not to interfere unduly with the generation of images by a 
scintillation camera positioned below a patient. A fifth advantage of the 
present invention is that a patient may be partially pass through the 
orifice defined by the annular rotating support so that the pair of arms 
need not be as long. A sixth advantage of the present invention is that 
the patient support may be accurately positioned relative to the annular 
support. A seventh advantage of the present invention is that the patient 
support does not interfere either with the rotation of the annular support 
or with the cables which will inevitably extend from the detector head to 
a nearby computer or other user control. 
Other advantages, objects and features of the present invention will be 
readily apparent to those skilled in the art from a review of the 
following detailed descriptions of preferred embodiments in conjunction 
with the accompanying drawings and claims.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIGS. 1 to 9, a nuclear camera 5 is supported and positioned 
relative to a patient by a support structure 10. Nuclear cameras are 
heavy, usually weighing approximately three to four thousand pounds. Thus, 
the support structure 10 should be strong and stable in order to be able 
to position the camera 5 safely and accurately. The support structure 10 
includes a base 15, an annular support 20, an elongate support 25, and a 
guide 30. 
The base 15 includes a frame 35. The frame 35 includes twelve lengths of 
square steel tubing welded together in the shape of a rectangular 
parallelepiped. The frame 35 has a front square section 37 and a rear 
square section 38. In the illustrated embodiment, the frame 35 is 
approximately five feet wide, five feet high, and two feet deep. The frame 
35 also includes eight triangular comer braces 40 welded to the front 
square section 37, that is, each corner of the front square section 37 has 
two comer braces 40, one towards the front of the front square section 37, 
and one towards the rear of the front square section 37. In the 
illustrated embodiment, the comer braces 40 are in the shape of 
equilateral right angle triangles. 
Attached to the underside of the frame 35 are two horizontal legs 45. 
Attached to each leg 45 are two feet 50. An alternative to the use of feet 
50 is to attach the base 15 to a floor by way of bolts set into the floor. 
The legs 45 extend beyond the frame 35 so as to position the feet 50 wider 
apart to increase the stability of the base 15. The feet 50 are adjustable 
so that the base 15 may be levelled. Thus constructed, the base 15 is 
strong, stable, rigid, and capable of supporting heavy loads. 
The annular support 20 is vertically oriented, having an inner surface 55 
defining an orifice 60, an outer surface 65, a front surface 70, and a 
rear surface 75. The annular support 20 is constructed of a ductile iron 
casting capable of supporting heavy loads. In the illustrated embodiment, 
the annular support 20 has an outside diameter of about fifty two inches. 
The annular support 20 is supported by upper rollers 80 and lower rollers 
85 which are mounted on the base 15. The upper rollers 80 and lower 
rollers 85 roll on the outer surface 65, thus enabling the annular support 
20 to rotate relative to the base 15 in the plane defined by the annular 
support 20. Each of the upper rollers 80 and lower rollers 85 are mounted 
onto a pair of comer braces 40 by way of axles with deep groove bearings. 
The bearings should be low friction and be able to withstand heavy loads. 
The axles of the upper rollers 80 are radially adjustable relative to the 
annular support 20, so that the normal force exerted by the upper rollers 
80 on the outer surface 60 is adjustable. The curved surfaces of the upper 
rollers 80 and lower rollers 85 (i.e. the surfaces that contact the outer 
surface 60) should be tough so as to be able to withstand the pressures 
exerted by the annular support 20, and should have a fairly high 
coefficient of friction so as to roll consistently relative to the annular 
support 20. 
Attached to each pair of corner braces 40 is a stabilizing arm oriented 
perpendicularly to the plane of the annular support 20. A pair of small 
stabilizing rollers are mounted onto each stabilizing arm 90. Each pair of 
stabilizing rollers is positioned such that one stabilizing roller rolls 
on the front surface 70, and the other stabilizing roller rolls on the 
rear surface 75. The stabilizing rollers maintain the annular support 20 
in the vertical plane. 
The elongate support 25 includes a pair of support arms 100, each of which 
extends through an aperture in the annular support 20. The nuclear camera 
5 is rotatably attached to one end of the pair of support arms 100, such 
that the nuclear camera 5 faces the front surface 70. A counter weight 105 
is attached to the other end of the pair of support arms 100, such that 
the counterweight 105 faces the rear surface 75. 
The counter weight 105 includes a pair of parallel counter weight members 
110, each of which is pivotally attached to one of the support arms 100. A 
first weight 115 is attached to one end of the pair of counter weight 
members 110, and a second weight 120 is attached to the other end of the 
pair of counter weight members 110. A pair of counter weight links 121 
connect the counter weight members 110 to the annular support 20. Each 
counter weight link 121 is pivotally attached at one end to its 
corresponding counter weight member 110. Each counter weight link 121 is 
pivotally attached at its other end to a counter weight bracket 122 which 
is rigidly attached to the annular support 20. The counter weight links 
121 are attached to the counterweight members 110 and counter weight 
brackets 122 using bolts and tapered roller bearings. Each counter weight 
link 121 is pivotable relative to the annular support 20 in a plane 
perpendicular to and fixed relative to the annular support 20. 
The guide 30 attaches the elongate support 25 to the annular support 20, 
and controls the position of the elongate support 25, and hence the 
scintillation camera 5, relative to the annular support 20. A pair of 
brackets 125 is rigidly attached to the annular support 20. A pair of 
rigid links 130 is pivotally attached at support arm pivot points 135 to 
the support arms 100. The pair of links 130 is also pivotally attached at 
bracket pivot points 140 to the brackets 125. At the support arm pivot 
points 135 and bracket pivot points 140 are tapered roller bearings 
mounted with bolts. Each link 130 is pivotable relative to the annular 
support 20 in a plane perpendicular to and fixed relative to the annular 
support 20. Thus, as the annular support 20 rotates relative to the base 
15, the respective planes in which each link 130 and each support arm 100 
can move remain fixed relative to the annular support 20. 
A pair of linear tracks 145 are rigidly attached to the front surface 70 of 
the annular support 20. The tracks 145 are oriented such that they are 
parallel to the respective planes in which each link 130 and each support 
arm 100 can move. A pair of rigid sliding arms 150 (not shown in FIG. 1) 
include camera ends 155 and straight ends 160. Each camera end 155 is 
pivotally attached to one of the support arms 100 at the point of 
attachment of the scintillation camera 5. Each straight end 160 includes a 
pair of spaced apart cam followers or guides 165 slidable within the 
corresponding track 145. Thus, movement of the scintillation camera 5 
relative to the annular support 20 (i.e. we are not concerned, at this 
point, with rotational movement of the scintillation camera 5 relative to 
the elongate support 25) is linear and parallel to the plane of the 
annular support 20. Note that if the camera ends 155 were pivotally 
attached to the support arms 100 between the nuclear camera 5 and the 
annular support 20, the movement of the nuclear camera 5 relative to the 
annular support 20 would not be linear. 
Movement of the scintillation camera 5 relative to the annular support 20 
is effected by an actuator 170. The actuator 170 includes a fixed end 175 
pivotally attached to the annular support 20, and a movable end 180 
pivotally attached to the elongate support 25. The actuator 170 is 
extendable and retractable, and is thus able to move the elongate support 
25 relative to the annular support 20. 
Movement of the annular support 20 relative to the base 15 is effected by a 
drive unit 185. The drive unit 185 includes a quarter horsepower permanent 
magnet DC motor and a gearbox to reduce the speed of the output shaft of 
the drive unit 185. Alternatively, other types of motors could be used, 
such as hydraulic or pneumatic motors. The output shaft of the drive unit 
185 is coupled, by means of a toothed timing belt 195 and two pulley 
wheels 200, to the axle of a drive roller 190, which is simply one of the 
lower rollers 85, thus driving the drive roller 190. Power is then 
transferred from the drive roller 190 to the annular support 20 by 
friction between the drive roller 190 and the outer surface 65 of the 
annular support 20. 
The support structure 10 of the illustrated embodiment is designed to 
operate with an apparatus for supporting and positioning a patient, such 
apparatus including a detached patient support 205 or bed, an engaged 
patient support 210 or pallet receiver, and a cylinder support or cylinder 
212. 
The detached patient support 205 includes rigid patient frame 215 supported 
by four casters 220. Mounted near the top of the patient frame 215 are 
first support wheels 225 for supporting a stretcher 227 having a flat 
lower surface and two parallel sides upon which a patient is lying. Two 
parallel, spaced apart side rails 230 are rigidly attached to the patient 
frame 215. The first support wheels 225 and the side rails 230 are 
arranged to enable the stretcher 227 to roll lengthwise on the detached 
patient support 205. Thus, if the patient support 205 faces the front 
surface 70 such that the patient support is central and perpendicular 
relative to the annular support 20, the stretcher 227 is movable on the 
first patient support wheels 225 substantially along the axis of the 
annular support 20. A gear box and motor unit 237 driving at least one of 
the first patient support wheels 225 moves the stretcher 227 as described. 
A 0.125 horsepower permanent magnet DC motor has been found to be 
adequate. 
The detached patient support 205 can be used both for transporting a 
patient to and from the scintillation camera 5 and support structure 10 
therefor, and for supporting and positioning a patient relative to the 
base 15 during operation of the scintillation camera 5 and support 
structure 10. To ensure that the detached patient support 205 remains 
stationary during operation of the scintillation camera 5, four brakes 233 
can be lowered. Thus lowered, the brakes 233 ensure that the detached 
patient support remains stationary relative to the floor. 
The engaged patient support 210 includes a second rigid frame or rigid base 
frame 234 and second support wheels 235. The second support wheels 235 are 
positioned such that the stretcher 227 rolled along the first support 
wheels 225 can roll onto the second support wheels 235 until the stretcher 
227 is either fully or partially supported by the second support wheels 
235. The engaged patient support 210 also includes four transverse wheels 
240. 
The cylinder 212 is rigidly mounted to the annular support 20. The cylinder 
212 is aligned with the orifice 60 of the annular support 20 such that the 
cylinder is coaxial with the annular support 20. The cylinder 212 includes 
a smooth inner surface 245 upon which rest the transverse wheels 240 of 
the engaged patient support 210. Thus, the arrangement is such that the 
patient remains stationary substantially along the axis of the annular 
support 20 as the annular support 20 rotates relative to the base 15, 
regardless of whether the board or stretcher is supported by the first 
support wheels 225, the second support wheels 235, or both. 
The engaged patient support 210 also includes a stabilizer 245. The 
stabilizer 245 includes outside wheels 250 to maintain the engaged patient 
support 210 horizontal, that is, to stop the engaged patient support from 
tipping relative to the cylinder 212. The outside wheels 250 roll on the 
outside surface 243 of the cylinder 212. The stabilizer 245 also includes 
end wheels 255 to prevent the engaged patient support 210 from moving in a 
direction parallel to the axis of the cylinder 212. The end wheels 255 
roll on the ends 244 of the cylinder 212. 
Numerous modifications, variations and adaptations may be made to the 
particular embodiments of the invention described above without departing 
from the scope of the invention, which is defined in the claims.