Note: Descriptions are shown in the official language in which they were submitted.
CA 02385146 2005-03-23
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APPARATUS AND. METHOD FOR AUTOMATICALLY ADJUSTING THE
PATH OF A MEDICAL CAMERA
s'
Field of the Invention
The present invention relates to an apparatus and method for automatically
adjusting a relative distance between a patient body and a camera head in~ a
medical imaging system. .
.io 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 pafient,is detected using a radiation detector such as a
scintillation
camera.
is . Scintillation carrieras are well known in the art, and are used for
rriedical
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
2o small flash or scintillation of light, in response to stimulating
radiation, such as from .
a patient. The intensity of the scintillation, of fight 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
2s detector which converts into electrical signals gamma rays emitted from a
patierit
after radioisotope has been administered to the patient. Th.e detector
includes a
scintillator and photomultipUer 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
3o communication with the scintillation crystal, converts these flashes into
electrical
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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
s 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 camera head, allowing the collimator to be changed to enable the camera
head
to be used with the different energies of isotope to suit particular
characteristics of
the patient study. A collimator rnay vary considerably in weight to match the
isotope
io 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
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
2o 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.
2s The acronym "SPELT" stands for single photon emission computerized
tomography. A SPELT view is a series of slice-like images of the patient. The
slice-like images are often, but nat 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
3o the slice-like image. In order to be able to achieve a SPELT view, a
scintillation
camera must be rotatable around a patient, with the direction of the camera
head of
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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
s 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 camera head of the scintillation camera pointing in
a series
of known and precise directions such that reprojection of the data can be
accurately
to 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
1s 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 horizontalVy on a patient support or stretcher.
The camera head must also be positioned at a certain height relative to the
patient. It is commonly known in the art that when the collimator to patient
distance
20 is minimized, the better the image resolution develops. However, many
patients do
not feel comfortable with the camera head too close to them. An optimum
position
must be maintained to ensure a good quality view and patient comfort.
It is therefore necessar'~r to provide an apparatus for and a method of
automatically adjusting a relative distance between a camera head and a
patient in
2s a medical imaging system.
Summary of the Invention
According to one aspect of the present invention, there is provided an
apparatus for controlling a relative distance between a patient's body and a
camera
head in a medical imaging system, in which the camera head has a camera
surface
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defining a field of view where the patient's body is to be placed. The
apparatus
comprises: (a) a light source provided at one side of the field of view, the
light
source being adapted to emit a light beam which travels over and substantially
parallel to the camera surface; {b) a light detector provided at the other
side of the
s field of view, the light detector being adapted to detect said light beam
emitted from
said light source; (c) wherein, when in use, the camera head approaches the
patient's body or vice versa to take a picture and an interruption or
disturbance in
the light beam by said approaching patient's body is sensed by the light
detector;
and (d) means for adjusting a relative distance between the patient's body and
the
io ' camera surface according to the characteristics of the interruption or
disturbance
sensed by the light detector.
According to another aspect of the invention, there is.provided an apparatus
for adjusting a relative distance between a patient's body and a camera head
in a
medical imaging system, in whi~;h the camera head has a camera surface
defining a
is field of view where the patient's body is to be placed. The apparatus
comprises: (a)
a light source provided at one side of the field of view, said light source
being
adapted to emit a light beam in such a manner that the light beam can sweep
substantially the whole area of the camera surface; (b) a light detector
provided at
the other.side of the field of view, the light detector being adapted to
detect the
2o sweeping light beam at multiple heights over the camera surface; (c)
wherein, when
in use, the light beam is partially interrupted by a patient's body placed in
the field of
view: and (d) means for adjusting the relative distance between the camera
surface
and the patient's body according to the characteristics of the detected light
beam,
whereby the camera surface can be maintained at a predetermined distance from
2s the patient's body.
According to yet another aspect of the invention, there is provided a method
of controlling a relative distance between a patient's body arid a camera head
in a
medical imaging system, in which the camera head has a camera surface defining
a
field of view where the patient's body is to be placed. The method comprises
steps
30 of: (a) projecting a light beam from one side of the field of view in such
a manner
that the light beam travels over and substantially parallel to the camera
surface; (b)
detecting the light beam at the other side of the field of view, wherein the
light beam
is interrupted by the patient placed in the filed of view; (c) analysing the
interrupted
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characteristics in the detected light beam; and (d) adjusting the relative
distance
between the camera surface and the patient's body according to the analysed
result, whereby the camera surface can be maintained at a predetermined
distance
from the patient's body.
s A further understanding' of other advantages, objects and features of the
present invention will be realized by reference to the following description,
appended claims, and accompanying drawings.
Brief Description of the Drawings
The embodiments ofthe invention ~ivill now be described with reference to the
io accompanying drawings, in which:
Fig. 1 is a perspective view of a scintillation camera including a detached
patient support in accordance with the inventions
Fig. 2 is a perspective view of the guide of a scintillation camera;
Fig. 3 is a front elevation view of a scintillation camera;
is Fig. 4 is a side elevation view of a scintillation camera;
Fig. 5 is a side elevation view of a scintillation camera;
Fig. 6 is a front elevation view of a scintillation camera;
Fig. 7 is a top plan view of a scintillation camera;
Fig. 8 is a perspective view of the scintillation camera of Figure 1,
including
2o the detached patient. support and engaged patient support, with the
stretcher
removed;
Fig. 9 is a side view of a portion of the patient support apparatus;
Fig. 10 is a perspective view of the positioner;
Fig. 11 is a side elevation view of the positioner;
2s Fig. 12 is a front elevation view of the positioner;
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Figs. 13 illustrates a perspective view of an apparatus for controlling a
relative distance between a camera head and a patient's body in a medical
imaging
system according to one embodiment of the invention;
Fig. 14 shows a top view of the apparatus of Fig. 13;
s Fig. 15 illustrates a perspective view of another embodiment of the present
invention;
Fig. 16 schematically shows an alternative form of Fig. 15;
Fig. 17 depicts a perspective view of yet another embodiment of the present
invention;
io Fig. 18 shows a frontal view of Fig. 17;
Figs. 19 and 20 illustrate embodiments of a light source and detector which
can be used in the present invention; and
Fig. 21 illustrates another embodiment of a light source and detector which
can be used in the present invention.
is Detailed Descrption of the Preferred Embodiments)
Before describing the preferred embodiments) of the present invention, a
general configuration and operation of a scintillation camera will be
detailed, where
the present invention can be applied. However, it is to be noted.that the
invention
can be used in any medical carnera environment.
20 Referring to Figs. 1 to 12, a scintillation 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
2s 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.
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The frame 35 has a front square section 37 and a rear square section 38. The
frame 35 is approximately five feet wide, five feet high, and two feet deep.
The
frame 35 also includes eight triangular corner braces 40 welded'to the front
square
section 37, that is, each corner of the front square section 37 has two corner
braces
s 40., one towards the front of the front square section 37, and one towards
the rear of
the front square section 37. The corner 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
io 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. -
is The annular support 20 is vertically oriented, having an inner surface 55
defining an orifice 60, an outer su dace 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. The annular support 20 has an outside diameter of about fifty two
inches (about 132 centimeters.). The annular support 20 is supported by upper
Zo 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 onta
a
pair of corner braces 40 by way of axles with deep groove bearings. The
bearings
Zs 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 65 is
adjustable.
The curved surfaces of the upper rollers. 80 and lower rollers 85 (i.e. the
surfaces
that contact the outer surface 65) should be tough so as to be able to
withstand the
30 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 (not shown)
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oriented perpendicularly to the plane of the annular support 20. A pair of
small
stabilizing rollers are mounted (not shown) onto each stabilizing arm. 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
s 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
io 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 weigfit members 11 D,
and a
is 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 annuiar support 20. Each counter weight link 121 is
pivotally
attached at one erid to its corresponding counterweight member 110. Each
counter
weight fink 121 is pivotally attached at its other end to a counter weight
bracket 122
2o which is rigidly attached to the annular support 20. The counter weight
links 121 are
attached to the counterweight members 110 and counterweight 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.
2s 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
3o 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
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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.
s 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
io arms 100 at the point of attachrnent 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. w~e are not concerned, at this point, with
rotational
movement of the scintillation camera 5 relative to the elongate support 25) is
linear
is 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
2o 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
2s 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,
3o 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.
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The support structure 10 is designed to operate with an apparatus for
supporting and positioning a patient, such apparatus including a detached
patient
support 205, an engaged patient support 210, and a cylinder 245.
The detached patient support 205 includes rigid patient frame 215 supported
s by four casters 220. Mounted near the top of the patient frame 215 are first
support
wheels 225 for supporting a stretcher 227 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
to 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
is 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 positioriing a patient relative to the base 15 during operation
of the
scintillation camera 5 and support structure 10. To ensure that the detached
patient
ao support 205 remains stationary during operation of the scintillation camera
5, four
stabilizers 233 can be lowered. Thus lowered, the stabilizers 233 ensure that
the
detached patient support remains statioriary relative to the floor.
The engaged patient support 210 includes second support wheels 235. The
second support wheels 235 are positioned such that the stretcher 227 rolled
along
2s 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 245 is rigidly mounted to the annular support 20. The cylinder
245 is aligned with the orifice 60 of the annular support 20 such that the
cylinder is
3o coaxial with the annular support 20. The cylinder 245 includes a smooth
inner
surface 246 upon which rest the transverse wheels 240 of the engaged patient
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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.
s The engaged patient support 210 also includes a stabilizer 250. The
stabilizer 250 includes outside wheels 255 to maintain the engaged patient
support
210 horizontal, that is, to stop tfle engaged patient support from tipping
relative to
the cylinder 245. The outside wheels 255 roll on the outside surface 243 of
the
cylinder 250. The stabilizer 245 also includes end wheels 256 to prevent the
to engaged patient support 210 from moving in a direction parallel to the axis
of the
cylinder 215. The erid wheels 256 roll on the ends 244 of the cylirider 245.
Referring to Figs.10,11 and 12, a camera head 305 of the nuclear camera 5
is supported between the two support arms 100 by a positioner 320. The camera
head 305 includes a casing 3'10 in which is contained a scintillation crystal
and
is photomultiplier tubes. Attached to the underside of the casing 310 is a
collimator
plate 315. The collimator plate 315 is made of lead perforated by narrow
channels,
and includes a collimator support 325 extending from the two edges of the
collimator plate adjacent the support arms 100. The collimator plate 315 is
attached
to the casing 310 by way of bolts.311. By removing the bolts 311, the
collimator
2o plate 315 can be removed from ttie casing 310 and replaced by another
collimator
plate 315. A particulardesign and weight of collimator is selected depending
on the
isotope being used or the type of study being conducted. Thus, the collimator
plate
315 must be changed from time to time. Since the collimator plates 315 vary
considerably in weight from one to another, the location of centre of gravity
of the
2s camera head 305 is dependent upon the weight of the collimator plate 315
attached
to the casing 310. Since the angle of the camera head 305 relative to the
patient
must be adjusted by an operator of the nuclear camera 5, the camera head 305
must be rotatable relative to the arms 100. If the centre of gravity of the
camera
head 305 is positioned approximately on the axis of rotation of the camera
head
3o relative to the support arms 100, then the camera head 305 will be
balanced, and
the angle of the camera head 305 relative to the support arms 100 will be
adjustable
by hand. However, changing them collimator plates moves the centre of gravity
of the
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camera head. Since collimator plates 315 are so heavy, it becomes inconvenient
or
impossible to adjust the angle of the camera head 305 by hand. The positioner
320
enables the operator to adjust the position of the centre of gravity of the
camera
head 305 to be. approximately aligned with the point of rotation of the camera
head
s 305, which passes through the support arms 100.
The positioner 320 attaches the camera head 305 to the support arms 100
and includes a pair of rigid elongate camera head links 330 for aligning the
centre of
gravity of the camera head 305 relative to the support arms 100. Each camera
head
link 330 is rotatable relative to the support arms 1 UO in a plane
substantially parallel
to to its adjacent support arm 100. Each camera head link 330 includes an arm
end
335 rotatably attached to the adjacent support arm 100 by way of an arm axle
340.
Each camera head link 330 also includes a head end 345 rotatably attached to
the
camera head 305 by way of a head axle 350.
The positioner 320 also includes a pair of locks 355 for selectively
preventing
is rotation of the camera head 305 relative to the camera head links 330. Each
lock
355 includes the collimator support 325 extending 305 from the collimator
plate 315.
Each lock 355 also includes a block 360 for supporting the camera head link
330 on
the collimator support 325. Each block 360 includes a pair of pins 365 located
either
side of the head axle 350.
2o In operation, each lock 355 supports the head end 345 of one of the camera
head links 330 on the corresponding collimator support 325. Thus, the distance
between the head axle 350 and the collimator support 325 remains constant, and
rotation of the camera head 305 relative to the camera head link 330 is
prevented.
If a heavier collimator plate 315 is installed, shorter pins 365 are
installed,
2s thus reducing the distance between the head axle 350 and the collimator
support
325, and aligning the centre of gravity of the camera head 305 with the axis
of
rotation of the camera head 305, which passes through the arm axles 340.
If a lighter collimator plated 315 is installed, longer pins 365 are
installed, thus
increasing the distance between the head axle 350 and the collimator support
325,
3o and aligning the centre of gravity of the camera head 305 with the axis of
rotation of
the camera head 305, which passes through the arm axles 340.
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Once the locks 355 ire in place, the camera head 305 will be balanced, and
the camera head 305 can be rotated manually by the operator. Once the camera
head 305 has been rotated to the desired position relative to the support arms
100,
a brake (not shown) can be implemented to selectively prevent rotation of the
s camera head link about the arrn axle 340.
As previously discussed, the camera head should be positioned at an ideal
height relative to the patient's body for producing a clear view while
maintaining
patient comfort. Thus, the present invention is to provide an apparatus and
method
for controlling or adjusting a relative distance between the camera head and
the
to patient's body.
In Figs.13 and 14, there is schematically shown an apparatus for controlling
a relative distance between a camera head and a patient's body in a
scintillation
camera system. Fig. 13 is a perspective view of the apparatus and Fig. 14 is a
top
view thereof: As noted above, the invention can be applied to any medical
imaging
is system which is required to be~ maintained at a certain distance from a
patient's
body. As depicted in Figs.13 and 14, the apparatus, which is generally denoted
by
a reference numeral 400, comprises a light source 420 mounted on one side of a
camera head 410 and a light detector 430 mounted on the other side of the
camera
head 410. The camera head 400 includes a camera surface 412, which defines a
2o field of view where the patient'; body is to be placed to take a picture.
Therefore,
the light source 420 is disposed at one side of the field of view, and the
light
detector 430 at the other side of the field of view of the camera head 410.
The light source 420 and detector 430 are, for example detachabfy, mounted
on the camera head 410 such that the collimator plates thereof can be easily
2s removed and replaced
For the convenience of description, it will be assumed that the camera head
410 is operated in a rectangular coordinate system. The X and Y-axes lie in
the
plane of the camera surface 412 , while axis Z runs through the camera surface
412.
The Z-axis is the axis along which the camera head 410 moves along during
3o adjusting the relative distance between the camera surface 412 and the
patient's
body, as shown in Fig. 1 or 8.
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In operation, the light source 420 emits a light beam, which travels through
the field of view defined by the camera surtace 412 and substantially parallel
to the
surface 412. As is shown in Fig. 13, the light beam emitted from the light
source
420 travels over the camera surface while maintaining a predetermined distance
d
s from the camera surface 412. The light detector 430 detects the light beam
which
has travelled across the camera surface 412. Therefore, when a patient's body
approaches the camera head (i.e., the camera surface 412) or vice versa to
take a
picture, the light beam wilt be interrupted or disturbed by the approaching,
patient.
Then, the interruption or disturbance of the light beam will be sensed by the
light
~o detector 430, compared with a normal detection without any interruption or
disturbance in the light beam. According to the pattern or characteristics of
the
disturbance sensed by the light detector 430, the distance between the
patient's
body and the camera surface 412 can be controlled. For example, in this
embodiment, when any interruption or disturbance in the light beam is detected
by
is . the light detector 430, the camera head 410 or the patient's body stops
further
approaching, thereby maintaining the patent's body at the predetermined
distance d
from the camera surface 412 or vice versa. The distance d can be adjusted,
depending on the study.
The light source 420 includes any kind of visible or invisible light emitting
2o devices, as long as the light emitted therefrom is not .transmittable
through the
patient body and can be detected by the light detector 430. For example, the
light
source may include a laser, which has a good controllability in the beam size,
cross-
section and width. The light detector 430 also includes any kind of photo-
detectors
or photo-sensors if they can detect the light beam emitted by the light source
and
2s sense any interruption or disturbance in the detected light beam. For
example, the
tight source may include a charge coupled device (CCD) or a photodiode.
Fig. 15 schematically depicts another embodirnenf of the apparatus of the
invention. In this embodiment, the physical components are almost the same as
in
the previous embodiment of Figs. 13 and 14, except for the shape. of the light
30 detector. As shown in Fig. 15, the light detector 430 takes an elongated
shape
formed parallel to the camera surface 412. The light source 420 is designed to
oscillate or rotate such that the light beam can sweep over the camera surface
12
CA 02385146 2002-05-07
as indicated by an arrow A and be detected by the elongated light detector 430
during the oscillation or rotation of the source 420, thereby more efficiently
detect
approaching the patient body. In this case, the light detector 430 can be much
longer than is shown in Fig. 15 .such that the sweeping light beam can cover
even
s larger area of the camera surface 412. Figs. 19 and 20 schematically
illustrate two
examples of the elongated light detector 430. As shown in Fig.19, the light
detector
430 comprises a plurality of photo-sensors 431 arranged parallel to the camera
surface 412. During the sweeping of the light, the photo-sensors 431 detect
the
light beam in succession, and also sense any interruption or disturbance of
the
io beam by a patient's body when and where it occurs. Alternatively, as
depicted in
Fig. 20, the elongated light detector 430 can comprise an optical bar 433, for
example, a sheet of PlexiglasT"", for receiving the sweeping fight beam, and a
photo-
sensor 434 disposed at one E;nd of the optical bar 433 for detecting the light
received therein. The photo-sensor 434 can be disposed at any position where
it
is can detect the light received in the optical bar 433 (the sheet of
PlexiglasT"" ). In the
embodiment of Fig. 20, the received light beam will be reflected and dispersed
repeatedly therein and brighten the inside of the sheet 433 such that it can
be
detected or sensed by the photo-sensor 434.
Fig. 16 schematically illustrates another embodiment similar to the previous
one of Fig. 15. In this embodiment, the apparatus 400 .further comprises an
additional light source 422 and an additional elongated light detector432.
Similar to
Fig. 15, the additional light source 422 is also adapted to oscillate or
rotate in such a
manner that a light beam emitted therefrom can sweep over the camera surface
412 as indicated by an arrow B and be detected by the additional elongated
light
2s detector 432 during the sweeping of the light. The additional light
detector 432 can
also take the form as depicted in Fig. 19 or 20. Due to the irregular profile
of the
approaching patient's body, an interruption or disturbance in the light beam
can
occur anywhere over the camera surface 412. Therefore, with the apparatus 400
of
this embodiment, the light beam can sweep substantially the whole area of the
3o camera surface 412 such that it can more efficiently detect the
interruption or
disturbance of the light beam wherever it occurs over the camera surface,
thereby
to more effectively control the reNative distance between the patient's body
and the
camera head 410.
CA 02385146 2002-05-07
16
In the embodiment of Fig. 15, the light source 420 can take an elongated
shape, instead of the oscillating or rotating thereof. That is, the elongated
light
source 420 can emit, for example, a sheet-like light beam parallel to the
camera
surface 412 while maintaining a distance d therefrom although not shown in
Fig. 15.
s Alternatively, the elongated light source can comprise a plurality of light
emitters
arranged parallel to the camera surface 412, each of which corresponds to each
respective photo-sensor of Fig. 19. Thus, each light beam emitted by each
light
emitter will be detected by each respective photo-sensor 431 of the, light
detector
430. The light emitter may include a laser. Therefore, as in the previous
to embodiment of Fig. 16, the sheet-like light beam or the multiple light
beams can
cover substantially the whole area of the camera surface 412 such that the
apparatus can more efficiently and effectively control the relative distance d
between the patient's body and the camera head 410.
Fig. 17 schematically depicts yet another embodiment of the apparatus of the
is invention, which comprises an elongated light source 428 and an elongated
light
detector438, both being arranged perpendicular to the camera surface 412. In
this
embodiment, the light source 428 is adapted to emit a sheet-like beam
substantially
perpendicular to the camera surface 412 and the light detector 438 is adapted
to
detect the sheet-like beam at multiple heights over the camera surface as
shown in
2o Fig. 17. The elongated light detector can take a form similar to that of
Fig. 19, i.e.,
comprise a plurality of photo-sensors 439 arranged perpendicular to the camera
surface 412. The photo-sensor may include a charge coupled device (CCD) or a
photodiode. Each photo-sensor 439 can correspond to each respective height.
Therefore, the distance of a patient from the camera surface can be more
efficiently
2s and flexibly controlled as shown in Fig: 18, which is a frontal view of
Fig. 17. Also, a
certain distance d can be pre-set programmably in a camera control electronic
(not
shown).
Further, the light source 428 can be adapted to emit multiple light beams
arranged perpendicular to the camera surface, instead of the sheet-like beam.
For
3o example, the elongated light source 428 can comprise a plurality of light
emitters
429 as depicted in Figs. 17 and 18, where each light emitter 429 corresponds
to
each respective photo-sensor 439 in the same operational mode as noted above.
CA 02385146 2002-05-07
17
The light emitter may include a~ laser.
In the embodiment illustrated in Figs. 17 and 18, the fight source 428 can
oscillate or rotate such that the sheet-like beam or the multiple light beams
sweep
over the camera surface 412> in substantially the same operational mode as
noted
s above in conjunction with Fig. '15. In this case, the light detector 438
comprises a
plurality of photo-sensors 439 arranged in rows and columns as illustrated in
Fig.
21. Alternatively, the light detector 438 can comprise multiple layers of the
elongated light detectors 430 depicted in Fig. 19 or 20.
Further, an additional oscillating light source and an additional light
detector
to can be provided and operated in substantially the same mode as in Fig.16.
That is,
the additional light source is adapted to emit a sheet-like beam or multiple
light
beams arranged perpendicular to the camera surface and to oscillate or rotate
in
such a manner that the additional light beam can sweep over the camera
surface.
The additional light detector can comprise a plurality of photo-sensor
arranged in
is rows and columns which can dE~tect the additional light beam during the
oscillation
of the additional light source. Therefore, the light beams emitted by the two
light
sources can sweep substantially the whole area of the camera surface, as
illustrated in Fig. 18.
Furthermore, the light source 428 and detector 438 both can take a form
as illustrated in Fig. 21. That is; the light source 428 comprises a plurality
of light
emitters arranged in rows and columns and the light detector 438 a plurality
of
photo-sensors arranged in rows and columns. Each light emitter corresponds to
each respective photo-sensor. As is apparently understood to those skilled in
the
art, the light source and detector, or every light emitter and photo-sensor
thereof
2s can be communicatively and operatively connected to a camera control
circuitry or a
separate control unit. Therefore, the apparatus of this embodiment can detect
the
profile of the patient's body whilE: taking pictures such that it can more
efficiently and
effectively control, in real time, the distance of the patient's body from the
camera
surface, especially when carrying out a whole body scanning.
3o For a whole or partial body scan, the camera head ,410 moves along the X-
axis, i.e., in the longitudinal direction of the patient, as discussed above
in
conjunction with Figs. 1 - 12. The apparatus of the invention will
automatically
CA 02385146 2002-05-07
18
adjust the camera head at an optimum distance from the patient during scanning
the body according to the profile of the patient. After scanning the body, the
camera
path along the patient profile can be memorized in a camera processing
computer
or unit. This data 'can be advantageously used for a subsequent can or for a
s multiple scanning study.
In some instances, the camera head is required to rotate around a patient's
body to take different views thereof. The apparatus of the present invention
will
provide a good controllability in maintaining an optimum distance of the
patient body
from the camera surface, for example, in combination with the structure and
to operation of the camera system as discussed above in connection with Figs.
1 to
12.
While the presentinvention has been described with reference to several
specific embodiments, the description is of illustrative of the invention and
is not to
be construed as limiting the invention. Various modifications and variations
may
is occur to those skilled in the art without departing from the true spirits
and scope of
the invention as defined by the appended claims.
