CA2326025A1 - Scintillation camera comprising at least three fields of view - Google Patents
Scintillation camera comprising at least three fields of view Download PDFInfo
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- CA2326025A1 CA2326025A1 CA002326025A CA2326025A CA2326025A1 CA 2326025 A1 CA2326025 A1 CA 2326025A1 CA 002326025 A CA002326025 A CA 002326025A CA 2326025 A CA2326025 A CA 2326025A CA 2326025 A1 CA2326025 A1 CA 2326025A1
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- 230000000747 cardiac effect Effects 0.000 description 14
- 230000005855 radiation Effects 0.000 description 13
- 238000003384 imaging method Methods 0.000 description 12
- 238000002603 single-photon emission computed tomography Methods 0.000 description 9
- 230000005484 gravity Effects 0.000 description 7
- 230000000087 stabilizing effect Effects 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 210000000988 bone and bone Anatomy 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical compound [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 description 3
- 239000003381 stabilizer Substances 0.000 description 3
- 0 CCCCC(CCCC(C)(C)CCCC1=C**CC1)CCC=C Chemical compound CCCCC(CCCC(C)(C)CCCC1=C**CC1)CCC=C 0.000 description 2
- 210000004556 brain Anatomy 0.000 description 2
- 210000004185 liver Anatomy 0.000 description 2
- 230000002503 metabolic effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- 230000004936 stimulating effect Effects 0.000 description 2
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 235000004240 Triticum spelta Nutrition 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- 238000002583 angiography Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009206 nuclear medicine Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 235000009518 sodium iodide Nutrition 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003325 tomography Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
- A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
- A61B6/4258—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector for detecting non x-ray radiation, e.g. gamma radiation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
- G01T1/164—Scintigraphy
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computed tomography [CT]
- A61B6/037—Emission tomography
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Engineering & Computer Science (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Biomedical Technology (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- General Health & Medical Sciences (AREA)
- Pathology (AREA)
- Biophysics (AREA)
- Radiology & Medical Imaging (AREA)
- Heart & Thoracic Surgery (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Nuclear Medicine (AREA)
Abstract
Disclosed is a scintillation camera comprising two detector heads mounted to a rotating support. The two detector heads are diametrically opposed. The first detector head comprises a L- shaped rigid structure comprising two detectors at 90 degrees to one another.
The second detector head comprises at least one detector.
The second detector head comprises at least one detector.
Description
Scintillation Camera Comprising At Least Three Fields of View Field The invention relates generally to scintillation cameras, and more particularly to an improved scintillation camera comprising at least three fields of view.
Background 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 1 S 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 "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 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. Depending on the type of study being conducted, the configuration of the radiation detector is variable. The two common types of studies are planar imaging and cardiac imaging.
Planar imaging is used for bone scanning and various other types including liver scanning.
In order to obtain optimum images, two cameras should be opposed one another.
In general, these cameras should also be relatively large in order to obtain a large field of view.
Cardiac imaging is used for obtaining images of the heart. In order to obtain optimum images, two detector heads and two collimators should be at substantially 90 degrees to one another, with their fields of view close as possible.
In an attempt to provide the ability to produce both types of images with a single scintillator machine, detectors of variable geometry were developed. These systems conduct both planar and cardiac imaging. However, the problem with these systems is that it is difficult, if not impossible, to position the heads to an exact same position where a prior image was taken from. This is primarily due to backlash in the mechanical structure of the system. When the computer conducts the reconstruction of the images, it does so with the assumption that the information it is writing into the pixels in the image display is in the correct place. With the presence of backlash, the computer is unknowingly writing information into the wrong place, which results in blurring of the image and loss of image resolution. This in turn results in images that are inaccurate. This also precludes any reproducability of the study.
Also, these systems use two separate and distinct detectors to produce the 90 degree view.
This means that it further requires lead shielding between the detectors to prevent any stray radiation from getting into each of the detectors. With the lead shielding between the detectors, the detectors are prevented from being as close together as possible in the 90 degree position; they are not as close as they would be without the shielding between them.
1 S Since then, the fields of view of the detectors are not close, this leaves open the risk of cutting off views of the heart as cardiac imaging is conducted.
These systems also, generally, can not easily vary in size of support to accommodate different sizes of patients. In order to do accommodate either a larger or smaller patient, the entire scintillation camera is physically repositioned.
The use of three detectors is known, but usually, these systems use three relatively little detectors which don't image bones well. The smaller fields of view of the detectors mean they can not produce whole body images or images of the skeleton.
Even if the system did utilize relatively large detectors, systems using three relatively large detectors have disadvantages. The detectors are generally set at 60 degrees from one another.
This results in the detectors wanting to slide over one another. As well, a 60 degree is not S
ideal for cardiac work. As mentioned above, the image should be taken at 90 degrees.
For this reason, it is beneficial to use a detector which comprises a rigid structure comprising two detector heads and two collimators fixed at 90 degrees to one another.
This detector is optimum for cardiac work, but with it, then, the scintillation camera becomes only a cardiac camera. As mentioned above, 90 degree views are only useful for cardiac studies and are not really useful in other studies.
Therefore, there exists a need for a scintillation camera optimal for both planar and cardiac imaging that mitigates the disadvantages mentioned above.
Summary An object of the invention is to provide an improved scintillation camera. The invention is directed to a scintillation camera with an improved three view detector system. Preferably, the camera is adapted to produce both optimized planar imaging and cardiac imaging.
The present invention has many advantages including:
the need for lead shielding is eliminated, thereby allowing the two fields of view to 1 S be as close together as possible;
designed for optimal cardiac imaging and eliminates the problems associated with backlash;
designed for optimum planar imaging and whole body imaging as well;
increased sensitivity over current two headed designs;
design is flexible and versatile;
size of support diameter is adjustable while being able to maintain the detectors in the ideal positions relative to each other.
Other aspects and advantages of the invention, as well as the structure and operation of various embodiments of the invention, will become apparent to those ordinarily skilled in the art upon review of the following description of the invention in conjunction with the accompanying drawings.
Brief Description of the Drawings The invention will be described with reference to the accompanying drawings, wherein:
FIG. 1 is a perspective view of a scintillator in accordance with the invention;
FIG. 2 is a perspective view illustrating the base in further detail with the cameras removed;
FIG. 3 is a perspective view of the mounting means for one camera;
FIG. 4 is a front elevation view of a scintillator in accordance with the invention;
FIG. S is a front elevation view of a scintillator with the cameras removed;
FIG. 6 is a side elevation view of a scintillator illustrating the counter weight for one camera;
FIG. 7 illustrates one camera in detail;
FIG. 8 illustrates a second camera in detail;
FIG 9. illustrates a positioner for a camera;
FIG 10. is a front elevation view of another embodiment in accordance with the invention;
FIG. 11 illustrates a patient support;
FIG. 12 is a perspective view of the scintillation camera of FIG. 1, including the detached patient support and engaged patient support, with the stretcher removed; and FIG. 13 is a side view of a portion of the patient support apparatus.
Similar references are used in different figures to denote similar components.
Detailed Description Referring to FIGS. 1 to 13, scintillator 500 is illustrated. Nuclear cameras 5 and 300 are 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 cameras 5 and 300 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 corner braces 40 welded to the front square section 37, that is, each corner of the front square section 37 has two corner 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 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 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 1 S 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 (not shown) oriented perpendicularly to the plane of the annular support 20. A pair of small stabilizing rollers (not shown) are mounted 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 stabilizing rollers maintain the annular support 20 in the vertical plane.
Each camera 5 and 300 is mounted to the annular support 20 by mounting means.
The mounting means can be of any type known in the art. 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 1 OS includes a pair of parallel counter weight members 110, 111 each of which is pivotally attached to one of the support arms 100. A first weight 1 OS is attached to one end of the pair of counter weight members 110, and a second weight 120 is attached to the other counter weight members 111. A pair of counter weight links 121 and 122 connect the counter weight members 110 and 111 to the annular support 20. Each counter weight link 121, 122 is pivotally attached at one end to its corresponding counter weight member 110, 111. Each counter weight link 121, and 122 is pivotally attached at its other end to the annular support 20. The counter weight links 121, 122 are attached to the counterweight members 110 using bolts and tapered roller bearings. Each counter weight link 121, 122 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 S, relative to the annular support 20. A pair of parallel brackets 125 is rigidly attached to the annular support 20. A parallel 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 5 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 (only one shown for simplicity )are rigidly attached to the front surface 70 of the annular support 20. The tracks 145 are oriented such that they are parallel 10 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, 1 S movement of the scintillation camera S relative to the annular support 20 (i.e. we are not concerned, at this point, with rotational movement of the scintillation camera S 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 S 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 cameras 5 and 300 relative to the annular support 20 is effected by actuators 170. Each 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.
Each 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 (not shown), 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 cameras 5 and 300 used for detection will now be described.
A detector head 305 of the nuclear camera 300 is supported between the two support arms 100. The detector head 305 includes a casing 310 in which is contained a scintillation crystal and 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 310. The collimator plate 315 provides a first field of view 275.
The collimator plate 315 is attached to the casing 310 by way of bolts 311. By removing the bolts 311, the collimator plate 315 can be removed from the casing 310 and replaced by another collimator plate 315. A particular design 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 centre of gravity of the detector head 3 05 is dependent upon the weight of the collimator plate 315 attached to the casing 310.
Since the angle of the detector head 305 relative to the patient must be adjusted by an operator of the nuclear camera 300, the detector head 305 must be rotatable relative to the arms 100. If the centre of gravity of the detector head 305 is positioned approximately on the axis of rotation of the detector head relative to the support arms 100, then the detector head 305 will be balanced, and the angle of the detector head 305 relative to the support arms 100 will be adjustable by hand. However, changing the collimator plates moves the centre of gravity of the detector head. Since collimator plates 315 are so heavy, it becomes inconvenient or impossible to adjust the angle of the detector head 305 by hand. The positioner 320 enables the operator to adjust the position of the centre of gravity of the detector head 305 to be approximately aligned with the point of rotation of the detector head 305, which passes through the support arms 100.
In a similar fashion, detector head 400 of the nuclear camera 5 is supported between the two support arms 100. The detector head 400 includes a casing 410 which is a L
shaped rigid structure. As illustrated, the casing allows two collimator plates 255 and 260 to be attached to the underside of the casing 410. The collimator plates 255 and 260 are at 90 degrees to one another. Each collimator plate 255 and 260 provides a second and third field of view 280 and 285 respectively. Each collimator plate 255 and 260 includes a scintillation crystal and photomultiplier tubes and operates in a similar fashion as camera 300.
The collimator plates 255 and 260 define an apex 290 at their meeting point.
It is seen that camera 300 is diametrically opposed from camera 5 along the annular support.
With the detector head 400 comprising a single rigid structure 410 with two collimators 255 and 260 fixed together at 90 degrees, no stray radiation can enter the other collimator. This eliminates the requirement for lead shielding between them. And without the lead shielding, the fields of view 280 and 285 of the camera 5 are closer together, resulting in minimized risk of cutting off views of the heart as during operation. Also the rigid structure also allows the camera 5 to be repositioned easily to an original position. This allows reproducability of studies.
The camera 5 is of an ideal geometry for cardiac studies. And with the camera 300, the three fields of view are of an ideal geometry for other organ work, especially brain and liver studies.
Each of cameras 5 and 300 are preferably supported by the support arms by a positioner 320.
The positioner can be of any type to allow for this rotational movement. One such positoner is described. 'The positioner 320 attaches the detector head 305 to the support arms 100 and includes a pair of rigid elongate detector head links 330 for aligning the centre of gravity of the detector head 305 relative to the support arms 100. Each detector head link 330 is rotatable relative to the support arms 310 in a plane substantially parallel to its adjacent support arm 100. Each detector head link 330 includes an arm end 335 rotatably attached to the adjacent support arm 100 by way of an arm axle 340, which allows each camera to be rotatably positioned in any desired angle relative to the patient. Each detector head link 330 also includes a head end 345 rotatably attached to the detector head 305 by way of a head axle 350.
The positioner 320 also includes a pair of locks 355 for selectively preventing rotation of the detector head 305 relative to the detector head links 330. Each lock 355 includes the collimator support 325 extending from the detector head 305 from the collimator plate 315.
Each lock 355 also includes a block 360 for supporting the detector 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.
In operation, each lock 355 supports the head end 345 of one of the detector 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 detector head 305 relative to the detector head link 330 is prevented.
If a heavier collimator plate 315 is installed, shorter pins 365 are installed, thus reducing the distance between the head axle 350 and the collimator support 325, and aligning the centre of gravity of the detector head 305 with the axis of rotation of the detector head 305, which passes through the arm axles 340.
If a lighter collimator plate 315 is installed, longer pins 365 are installed, thus increasing the distance between the head axle 350 and the collimator support 325, and aligning the centre of gravity of the detector head 305 with the axis of rotation of the detector head 305, which passes through the arm axles 340.
Once the locks 355 are in place, the detector head 305 will be balanced, and the detector head 305 can be rotated manually by the operator. Once the detector head 305 has been rotated to the desired position relative to the support arms 100, a brake 370 can be implemented to selectively prevent rotation of the detector head link about the arm axle 340.
In a preferred embodiment, the camera 5 and camera 300 are not mechanically joined together; each camera is mounted to the annular support by its own mounting means. This allows for the system to increase/decrease in size depending on the size of the patient.
Adjustments to the cameras do not affect the relative position of each camera and each field of view, only the relative distance between them. Since camera 5 is of a rigid construction, the fields of view 280 and 285 will always be maintained at a constant angle, which is preferably 90 degrees. As well, camera 300 will always be maintained at a position diametrically opposed the camera 5.
In a preferred embodiment, camera 300 is of a rectangular shape.
Also, in another preferred embodiment, the fields of view 275, 280 and 285 are in alignment with one another. With industry standard sizes, it is possible to provide optimum geometry for this configuration. While the cameras can be of any size, the camera 5 ideally is either 15 feet by 10.5 feet or 15 feet by 20 feet and the camera 300 is ideally 15 feet by 20 feet.
The invention also allows for complete flexibility in configuration choices and the ability to upgrade. For example, a scintillation camera could include only a single detector, such as detector 300. The scintillation camera could be upgraded to include the use of a second detector head, such as detector 400.
In an alternative embodiment, the camera 300 could be identical to camera 5, providing for a four field of view configuration. This would be very useful for brain studies since a very high sensitivity, high resolution image would result. The camera 5 could comprise a circular 5 or square shape as well.
The sizes of the cameras are variable.
In another alternative embodiment, the camera 5 could be rotated about supporting arms 100 and arm axles 340 so collimator plates 255 and 260 face out rather than down as seen in Figure 10. This configuration is useful for performing bi-plane angiography of the heart 10 where the heart is examined in two directions simultaneously.
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.
15 The detached patient support 205 includes rigid patient frame 21 S
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 scintillator S00 and support structure 10 therefor, and for supporting and positioning a patient relative to the base 15 during operation of the scintillation cameras 5 and 300 and support structure 10. To ensure that the detached patient support 205 remains stationary during operation of the scintillation cameras 5 and 300, 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 244 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.
The previously described embodiments of the present invention have many advantages including:
eliminating the need for lead shielding between the collimators at 90 degrees to one another, thereby allowing the fields of view to be a close together as possible;
ensuring cardiac studies are done accurately by using a fixed geometry which eliminates backlash and accomplishes reproducability;
allowing for accurate bone work and whole body views to be taken since three fields of view are provided;
increasing the sensitivity from only using two heads ;
permitting both optimum cardiac and other studies to be conducted with the same machine;
allowing flexibility and the ability to upgrade in the field; and adjusting the size of diameter of the annular support to accommodate all patients while being able to maintain the cameras in the right positions relative to each other.
While the invention has been described according to what is presently considered to be the most practical and preferred embodiments, it must be understood that the invention is not limited to the disclosed embodiments. Those ordinarily skilled in the art will understand that various modifications and equivalent structures and functions may be made without 1g departing from the spirit and scope of the invention as defined in the claims.
Therefore, the invention as defined in the claims must be accorded the broadest possible interpretation so as to encompass all such modifications and equivalent structures and functions.
Background 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 1 S 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 "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 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. Depending on the type of study being conducted, the configuration of the radiation detector is variable. The two common types of studies are planar imaging and cardiac imaging.
Planar imaging is used for bone scanning and various other types including liver scanning.
In order to obtain optimum images, two cameras should be opposed one another.
In general, these cameras should also be relatively large in order to obtain a large field of view.
Cardiac imaging is used for obtaining images of the heart. In order to obtain optimum images, two detector heads and two collimators should be at substantially 90 degrees to one another, with their fields of view close as possible.
In an attempt to provide the ability to produce both types of images with a single scintillator machine, detectors of variable geometry were developed. These systems conduct both planar and cardiac imaging. However, the problem with these systems is that it is difficult, if not impossible, to position the heads to an exact same position where a prior image was taken from. This is primarily due to backlash in the mechanical structure of the system. When the computer conducts the reconstruction of the images, it does so with the assumption that the information it is writing into the pixels in the image display is in the correct place. With the presence of backlash, the computer is unknowingly writing information into the wrong place, which results in blurring of the image and loss of image resolution. This in turn results in images that are inaccurate. This also precludes any reproducability of the study.
Also, these systems use two separate and distinct detectors to produce the 90 degree view.
This means that it further requires lead shielding between the detectors to prevent any stray radiation from getting into each of the detectors. With the lead shielding between the detectors, the detectors are prevented from being as close together as possible in the 90 degree position; they are not as close as they would be without the shielding between them.
1 S Since then, the fields of view of the detectors are not close, this leaves open the risk of cutting off views of the heart as cardiac imaging is conducted.
These systems also, generally, can not easily vary in size of support to accommodate different sizes of patients. In order to do accommodate either a larger or smaller patient, the entire scintillation camera is physically repositioned.
The use of three detectors is known, but usually, these systems use three relatively little detectors which don't image bones well. The smaller fields of view of the detectors mean they can not produce whole body images or images of the skeleton.
Even if the system did utilize relatively large detectors, systems using three relatively large detectors have disadvantages. The detectors are generally set at 60 degrees from one another.
This results in the detectors wanting to slide over one another. As well, a 60 degree is not S
ideal for cardiac work. As mentioned above, the image should be taken at 90 degrees.
For this reason, it is beneficial to use a detector which comprises a rigid structure comprising two detector heads and two collimators fixed at 90 degrees to one another.
This detector is optimum for cardiac work, but with it, then, the scintillation camera becomes only a cardiac camera. As mentioned above, 90 degree views are only useful for cardiac studies and are not really useful in other studies.
Therefore, there exists a need for a scintillation camera optimal for both planar and cardiac imaging that mitigates the disadvantages mentioned above.
Summary An object of the invention is to provide an improved scintillation camera. The invention is directed to a scintillation camera with an improved three view detector system. Preferably, the camera is adapted to produce both optimized planar imaging and cardiac imaging.
The present invention has many advantages including:
the need for lead shielding is eliminated, thereby allowing the two fields of view to 1 S be as close together as possible;
designed for optimal cardiac imaging and eliminates the problems associated with backlash;
designed for optimum planar imaging and whole body imaging as well;
increased sensitivity over current two headed designs;
design is flexible and versatile;
size of support diameter is adjustable while being able to maintain the detectors in the ideal positions relative to each other.
Other aspects and advantages of the invention, as well as the structure and operation of various embodiments of the invention, will become apparent to those ordinarily skilled in the art upon review of the following description of the invention in conjunction with the accompanying drawings.
Brief Description of the Drawings The invention will be described with reference to the accompanying drawings, wherein:
FIG. 1 is a perspective view of a scintillator in accordance with the invention;
FIG. 2 is a perspective view illustrating the base in further detail with the cameras removed;
FIG. 3 is a perspective view of the mounting means for one camera;
FIG. 4 is a front elevation view of a scintillator in accordance with the invention;
FIG. S is a front elevation view of a scintillator with the cameras removed;
FIG. 6 is a side elevation view of a scintillator illustrating the counter weight for one camera;
FIG. 7 illustrates one camera in detail;
FIG. 8 illustrates a second camera in detail;
FIG 9. illustrates a positioner for a camera;
FIG 10. is a front elevation view of another embodiment in accordance with the invention;
FIG. 11 illustrates a patient support;
FIG. 12 is a perspective view of the scintillation camera of FIG. 1, including the detached patient support and engaged patient support, with the stretcher removed; and FIG. 13 is a side view of a portion of the patient support apparatus.
Similar references are used in different figures to denote similar components.
Detailed Description Referring to FIGS. 1 to 13, scintillator 500 is illustrated. Nuclear cameras 5 and 300 are 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 cameras 5 and 300 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 corner braces 40 welded to the front square section 37, that is, each corner of the front square section 37 has two corner 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 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 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 1 S 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 (not shown) oriented perpendicularly to the plane of the annular support 20. A pair of small stabilizing rollers (not shown) are mounted 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 stabilizing rollers maintain the annular support 20 in the vertical plane.
Each camera 5 and 300 is mounted to the annular support 20 by mounting means.
The mounting means can be of any type known in the art. 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 1 OS includes a pair of parallel counter weight members 110, 111 each of which is pivotally attached to one of the support arms 100. A first weight 1 OS is attached to one end of the pair of counter weight members 110, and a second weight 120 is attached to the other counter weight members 111. A pair of counter weight links 121 and 122 connect the counter weight members 110 and 111 to the annular support 20. Each counter weight link 121, 122 is pivotally attached at one end to its corresponding counter weight member 110, 111. Each counter weight link 121, and 122 is pivotally attached at its other end to the annular support 20. The counter weight links 121, 122 are attached to the counterweight members 110 using bolts and tapered roller bearings. Each counter weight link 121, 122 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 S, relative to the annular support 20. A pair of parallel brackets 125 is rigidly attached to the annular support 20. A parallel 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 5 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 (only one shown for simplicity )are rigidly attached to the front surface 70 of the annular support 20. The tracks 145 are oriented such that they are parallel 10 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, 1 S movement of the scintillation camera S relative to the annular support 20 (i.e. we are not concerned, at this point, with rotational movement of the scintillation camera S 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 S 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 cameras 5 and 300 relative to the annular support 20 is effected by actuators 170. Each 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.
Each 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 (not shown), 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 cameras 5 and 300 used for detection will now be described.
A detector head 305 of the nuclear camera 300 is supported between the two support arms 100. The detector head 305 includes a casing 310 in which is contained a scintillation crystal and 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 310. The collimator plate 315 provides a first field of view 275.
The collimator plate 315 is attached to the casing 310 by way of bolts 311. By removing the bolts 311, the collimator plate 315 can be removed from the casing 310 and replaced by another collimator plate 315. A particular design 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 centre of gravity of the detector head 3 05 is dependent upon the weight of the collimator plate 315 attached to the casing 310.
Since the angle of the detector head 305 relative to the patient must be adjusted by an operator of the nuclear camera 300, the detector head 305 must be rotatable relative to the arms 100. If the centre of gravity of the detector head 305 is positioned approximately on the axis of rotation of the detector head relative to the support arms 100, then the detector head 305 will be balanced, and the angle of the detector head 305 relative to the support arms 100 will be adjustable by hand. However, changing the collimator plates moves the centre of gravity of the detector head. Since collimator plates 315 are so heavy, it becomes inconvenient or impossible to adjust the angle of the detector head 305 by hand. The positioner 320 enables the operator to adjust the position of the centre of gravity of the detector head 305 to be approximately aligned with the point of rotation of the detector head 305, which passes through the support arms 100.
In a similar fashion, detector head 400 of the nuclear camera 5 is supported between the two support arms 100. The detector head 400 includes a casing 410 which is a L
shaped rigid structure. As illustrated, the casing allows two collimator plates 255 and 260 to be attached to the underside of the casing 410. The collimator plates 255 and 260 are at 90 degrees to one another. Each collimator plate 255 and 260 provides a second and third field of view 280 and 285 respectively. Each collimator plate 255 and 260 includes a scintillation crystal and photomultiplier tubes and operates in a similar fashion as camera 300.
The collimator plates 255 and 260 define an apex 290 at their meeting point.
It is seen that camera 300 is diametrically opposed from camera 5 along the annular support.
With the detector head 400 comprising a single rigid structure 410 with two collimators 255 and 260 fixed together at 90 degrees, no stray radiation can enter the other collimator. This eliminates the requirement for lead shielding between them. And without the lead shielding, the fields of view 280 and 285 of the camera 5 are closer together, resulting in minimized risk of cutting off views of the heart as during operation. Also the rigid structure also allows the camera 5 to be repositioned easily to an original position. This allows reproducability of studies.
The camera 5 is of an ideal geometry for cardiac studies. And with the camera 300, the three fields of view are of an ideal geometry for other organ work, especially brain and liver studies.
Each of cameras 5 and 300 are preferably supported by the support arms by a positioner 320.
The positioner can be of any type to allow for this rotational movement. One such positoner is described. 'The positioner 320 attaches the detector head 305 to the support arms 100 and includes a pair of rigid elongate detector head links 330 for aligning the centre of gravity of the detector head 305 relative to the support arms 100. Each detector head link 330 is rotatable relative to the support arms 310 in a plane substantially parallel to its adjacent support arm 100. Each detector head link 330 includes an arm end 335 rotatably attached to the adjacent support arm 100 by way of an arm axle 340, which allows each camera to be rotatably positioned in any desired angle relative to the patient. Each detector head link 330 also includes a head end 345 rotatably attached to the detector head 305 by way of a head axle 350.
The positioner 320 also includes a pair of locks 355 for selectively preventing rotation of the detector head 305 relative to the detector head links 330. Each lock 355 includes the collimator support 325 extending from the detector head 305 from the collimator plate 315.
Each lock 355 also includes a block 360 for supporting the detector 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.
In operation, each lock 355 supports the head end 345 of one of the detector 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 detector head 305 relative to the detector head link 330 is prevented.
If a heavier collimator plate 315 is installed, shorter pins 365 are installed, thus reducing the distance between the head axle 350 and the collimator support 325, and aligning the centre of gravity of the detector head 305 with the axis of rotation of the detector head 305, which passes through the arm axles 340.
If a lighter collimator plate 315 is installed, longer pins 365 are installed, thus increasing the distance between the head axle 350 and the collimator support 325, and aligning the centre of gravity of the detector head 305 with the axis of rotation of the detector head 305, which passes through the arm axles 340.
Once the locks 355 are in place, the detector head 305 will be balanced, and the detector head 305 can be rotated manually by the operator. Once the detector head 305 has been rotated to the desired position relative to the support arms 100, a brake 370 can be implemented to selectively prevent rotation of the detector head link about the arm axle 340.
In a preferred embodiment, the camera 5 and camera 300 are not mechanically joined together; each camera is mounted to the annular support by its own mounting means. This allows for the system to increase/decrease in size depending on the size of the patient.
Adjustments to the cameras do not affect the relative position of each camera and each field of view, only the relative distance between them. Since camera 5 is of a rigid construction, the fields of view 280 and 285 will always be maintained at a constant angle, which is preferably 90 degrees. As well, camera 300 will always be maintained at a position diametrically opposed the camera 5.
In a preferred embodiment, camera 300 is of a rectangular shape.
Also, in another preferred embodiment, the fields of view 275, 280 and 285 are in alignment with one another. With industry standard sizes, it is possible to provide optimum geometry for this configuration. While the cameras can be of any size, the camera 5 ideally is either 15 feet by 10.5 feet or 15 feet by 20 feet and the camera 300 is ideally 15 feet by 20 feet.
The invention also allows for complete flexibility in configuration choices and the ability to upgrade. For example, a scintillation camera could include only a single detector, such as detector 300. The scintillation camera could be upgraded to include the use of a second detector head, such as detector 400.
In an alternative embodiment, the camera 300 could be identical to camera 5, providing for a four field of view configuration. This would be very useful for brain studies since a very high sensitivity, high resolution image would result. The camera 5 could comprise a circular 5 or square shape as well.
The sizes of the cameras are variable.
In another alternative embodiment, the camera 5 could be rotated about supporting arms 100 and arm axles 340 so collimator plates 255 and 260 face out rather than down as seen in Figure 10. This configuration is useful for performing bi-plane angiography of the heart 10 where the heart is examined in two directions simultaneously.
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.
15 The detached patient support 205 includes rigid patient frame 21 S
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 scintillator S00 and support structure 10 therefor, and for supporting and positioning a patient relative to the base 15 during operation of the scintillation cameras 5 and 300 and support structure 10. To ensure that the detached patient support 205 remains stationary during operation of the scintillation cameras 5 and 300, 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 244 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.
The previously described embodiments of the present invention have many advantages including:
eliminating the need for lead shielding between the collimators at 90 degrees to one another, thereby allowing the fields of view to be a close together as possible;
ensuring cardiac studies are done accurately by using a fixed geometry which eliminates backlash and accomplishes reproducability;
allowing for accurate bone work and whole body views to be taken since three fields of view are provided;
increasing the sensitivity from only using two heads ;
permitting both optimum cardiac and other studies to be conducted with the same machine;
allowing flexibility and the ability to upgrade in the field; and adjusting the size of diameter of the annular support to accommodate all patients while being able to maintain the cameras in the right positions relative to each other.
While the invention has been described according to what is presently considered to be the most practical and preferred embodiments, it must be understood that the invention is not limited to the disclosed embodiments. Those ordinarily skilled in the art will understand that various modifications and equivalent structures and functions may be made without 1g departing from the spirit and scope of the invention as defined in the claims.
Therefore, the invention as defined in the claims must be accorded the broadest possible interpretation so as to encompass all such modifications and equivalent structures and functions.
Claims (16)
1. A scintillation camera comprising:
a moveable support;
a first detector head mounted to the moveable support; and a second detector head mounted to the moveable support in a position relative to the first detector head, the first and second detector heads providing at least first, second and third fields of view.
a moveable support;
a first detector head mounted to the moveable support; and a second detector head mounted to the moveable support in a position relative to the first detector head, the first and second detector heads providing at least first, second and third fields of view.
2. The scintillation camera as claimed in claim 1, the first detector head comprising a rigid structure providing the first and second fields of view and the second detector head providing at least the third field of view.
3. The scintillation camera as claimed in claim 2, the second detector head being diametrically opposed the first detector head.
4. The scintillation camera as claimed in claim 2, the first and second fields of view being perpendicular to one another.
5. The scintillation camera as claimed in claim 4, the configuration of the second detector head being chosen from one configuration of the following group consisting of:
square, rectangular, circular or wherein the second detector head comprises two collimator plates fixed to one another substantially at 90 degrees.
square, rectangular, circular or wherein the second detector head comprises two collimator plates fixed to one another substantially at 90 degrees.
6. A scintillation camera comprising:
a base, the base having a rotating support;
a first detector head mounted to the rotating support by a first mounting means, the first detector head comprising a rigid structure comprising first and second collimator plates fixed to one another at a predetermined angle; and a second detector head mounted to the rotating support by a second mounting means in a position substantially diametrically opposed from the first detector head, the second detector head comprising a third collimator plate.
a base, the base having a rotating support;
a first detector head mounted to the rotating support by a first mounting means, the first detector head comprising a rigid structure comprising first and second collimator plates fixed to one another at a predetermined angle; and a second detector head mounted to the rotating support by a second mounting means in a position substantially diametrically opposed from the first detector head, the second detector head comprising a third collimator plate.
7. The scintillation camera as claimed in claim 6, the first and second collimator plates of the first detector head being angled at 90 degrees to one another.
8. The scintillation camera as claimed in claim 7, the first and second collimator plates of the first detector head comprising first and second fields of view respectively and the third collimator plate of the second detector head comprising a third field of view, the first and second fields of view and the third field of view being substantially aligned with one another.
9. The scintillation camera as claimed in claim 8, the first and second fields of view of the first and second collimator plates of the first detector head and the third field of view of the third collimator being aligned with one another.
10. The scintillation camera as claimed in claim 7, the second detector head being rectangular in shape.
11. The scintillation camera as claimed in claim 7, the second detector head being circular in shape.
12. The scintillation camera as claimed in claim 7, the second detector head comprising two collimator plates fixed to one another substantially at 90 degrees.
13. The scintillation camera as claimed in claim 7, the first mounting means comprising:
an elongate support comprising a pair of spaced apart arms extending through the rotating support, the elongate support comprising:
(i) a camera end for supporting a camera at a distance from the rotating support, the camera end being pivotally mounted to the camera.
an elongate support comprising a pair of spaced apart arms extending through the rotating support, the elongate support comprising:
(i) a camera end for supporting a camera at a distance from the rotating support, the camera end being pivotally mounted to the camera.
14. The scintillation camera as claimed in claim 13, the first and second detectors having variable distance between them, the first and second detector heads maintaining relative position to each other regardless of the distance between them.
15. The scintillation camera as claimed in claim 14, the configuration of the second detector head being chosen from one configuration of the following group consisting of:
square, rectangular, circular or wherein the second detector head comprises two collimator plates fixed to one another substantially at 90 degrees.
square, rectangular, circular or wherein the second detector head comprises two collimator plates fixed to one another substantially at 90 degrees.
16. A scintillation camera comprising:
a rotating support;
a first detector head mounted to the rotatable support, the first detector head comprising a rigid structure comprising two collimator plates fixed to one another substantially at 90 degrees, the collimator plates defining an apex; and a second detector head mounted to the rotatable support in a position substantially opposite the apex.
a rotating support;
a first detector head mounted to the rotatable support, the first detector head comprising a rigid structure comprising two collimator plates fixed to one another substantially at 90 degrees, the collimator plates defining an apex; and a second detector head mounted to the rotatable support in a position substantially opposite the apex.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002326025A CA2326025A1 (en) | 2000-07-21 | 2000-11-16 | Scintillation camera comprising at least three fields of view |
| CA 2349279 CA2349279C (en) | 2000-07-21 | 2001-05-31 | Scintillation camera having multiple fields of view |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2,314,205 | 2000-07-21 | ||
| CA002314205A CA2314205A1 (en) | 2000-07-21 | 2000-07-21 | Scintillation camera comprising at least three fields of view |
| CA002326025A CA2326025A1 (en) | 2000-07-21 | 2000-11-16 | Scintillation camera comprising at least three fields of view |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2326025A1 true CA2326025A1 (en) | 2002-01-21 |
Family
ID=25681967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002326025A Abandoned CA2326025A1 (en) | 2000-07-21 | 2000-11-16 | Scintillation camera comprising at least three fields of view |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2326025A1 (en) |
-
2000
- 2000-11-16 CA CA002326025A patent/CA2326025A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |