CA2179616C - Filmless x-ray apparatus and method of using the same - Google Patents
Filmless x-ray apparatus and method of using the sameInfo
- Publication number
- CA2179616C CA2179616C CA002179616A CA2179616A CA2179616C CA 2179616 C CA2179616 C CA 2179616C CA 002179616 A CA002179616 A CA 002179616A CA 2179616 A CA2179616 A CA 2179616A CA 2179616 C CA2179616 C CA 2179616C
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 230000005855 radiation Effects 0.000 claims abstract description 37
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 6
- 238000012545 processing Methods 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 claims description 10
- 238000003384 imaging method Methods 0.000 claims description 5
- 230000004913 activation Effects 0.000 claims description 4
- 238000002059 diagnostic imaging Methods 0.000 claims description 3
- 238000001429 visible spectrum Methods 0.000 claims description 2
- 239000011521 glass Substances 0.000 abstract description 3
- 230000002708 enhancing effect Effects 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 238000002601 radiography Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009232 chiropractic Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000007787 solid Substances 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
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B42/00—Obtaining records using waves other than optical waves; Visualisation of such records by using optical means
- G03B42/02—Obtaining records using waves other than optical waves; Visualisation of such records by using optical means using X-rays
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
- H05G1/64—Circuit arrangements for X-ray apparatus incorporating image intensifiers
-
- 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
- A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
- A61B6/508—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for non-human patients
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Medical Informatics (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Radiology & Medical Imaging (AREA)
- Surgery (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Optics & Photonics (AREA)
- Pathology (AREA)
- Biophysics (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Molecular Biology (AREA)
- High Energy & Nuclear Physics (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- General Physics & Mathematics (AREA)
- Apparatus For Radiation Diagnosis (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
A filmless X-ray apparatus and method of using the same include an X-ray source for directing X-rays through a biological subject, such as an animal or human, and through a fluorescent intensifying screen. An aluminum coated and lead back glass mirror reflects only the visible component of radiation passing through the fluorescent screen, to one or more video cameras. Video signals from the video camera are directed to frame grabber circuitry operably associated with a computer provided with image enhancing and processing software.
Description
1 DESCRIPTION 2 ~ ~ 9 6 1 6 3 "FILMLESS X-RAY APPARATUS AND METHOD OF USING THE SAME"
FIELD OF THE INVENTION
7 The present invention is directed to apparatus for 8 the direct detection and computer enhancement of X-rays 9 which obviates the need for X-ray film, developers, fixers, and processing equipment associated with prior art X-ray 11 methods. The inventive apparatus provides faster image 12 processing than conventional methods and requires less 13 exposure for the subject. The inventive method and 14 apparatus has advantages over the new computed radiography techniques including simplicity and potential for low cost 16 application. This X-ray method and apparatus of the present 17 invention has applications in many fields including airport 18 security systems, industrial quality control, and medicine.
BACKGROUND OF THE INVENTION
22 For almost eighty years photographic films have 23 been used both to capture and display X-rays for diagnostic 24 purposes. (See Figure 1) . Only in the last ten years have any alternative methods of X-ray imaging started to appear.
26 Best known of these is the expensive and complicated CAT
27 scan system used in many hospitals. Less well known 28 filmless X-ray systems are now available which use a storage 29 phosphor device to capture the X-ray image. These so called image plates can be scanned by a laser beam a short time 31 later, causing the image plates to emit light proportional 32 to the intensity of X-rays to which they were previously 33 exposed. Such systems are also complicated and expensive, 34 requiring special laser equipment for the scanning stage.
They have however clearly demonstrated the great advantages 36 of filmless, or digital, X-ray pictures.
37 Digital recorded X-rays are superior to those 38 recorded with photographic film due to the greater dynamic 39 range of the digital recording system. Photographic methods A
2179616 .
1 allow approximately one order of magnitude dynamic range 2 whereas digital methods typically allow four orders of 3 magnitude. This advantage is only realized if the actual 4 capture of the X-ray image is digital. Merely scanning a previously recorded photographic X-ray will not do. In 6 addition to the inherent advantages of the increased dynamic 7 range, computer image processing techniques provide a wealth 8 of capabilities to study otherwise obscured details within 9 the image. Accordingly, the present invention proposes a filmless X-ray apparatus and method of using the same which 11 has all the advantages of digitally captured radiography and 12 in addition is mechanically very simple. This allows the 13 apparatus to be made at much lower cost than current 14 systems, making it suitable for installation in many more locations, e.g. radiology clinics outside of hospitals, 16 veterinary clinics, chiropractic clinics, etc. The 17 inventive apparatus will be a particular boon to remote 18 settlements where "tele-medicine" is practised, such as 19 northern Canada and Alaska, because it allows an X-ray image signal to be transmitted over phone lines without an 21 unacceptable loss of resolution.
22 Turning to the published prior art, a patent of 23 interest is PCT application W081/03594, filed by Brown et 24 al. This publication discloses an x-ray apparatus comprising: a source of x-rays for directing x-rays through 26 an object (mail); a fluorescent intensifying screen behind 27 the object, for producing visible light radiation when 28 contacted by the x-rays; a light source for producing 29 visible light radiation as a reference; a movable mirror, aligned with the screen, for reflecting the visible light 31 radiation and reflecting the x-rays, to separate them, in 32 one mode, and for passing the reference visible light 33 radiation, in the other mode; a video camera for scanning 34 the test and reference visible light images and producing signals indicative thereof; circuit and computer means for 36 capturing the test image and processing it to measure the 37 amounts of transmission through light and dark areas of the A
1 object and to compare these measurements against the 2 reference measurements to detect the presence of IED's (an 3 explosive device in the envelope).
4 Another patent of interest is U.S. patent 4,063,092 issued to Berdahl. This patent teaches a system 6 involving: an x-ray source for directing x-rays through a 7 biological subject; an electronic image intensifier behind 8 the subject, for amplifying an electrical signal produced by 9 the x-rays and in turn producing visible light radiation; a lens for collimating the light; a beam splitting mirror 11 which splits the light and directs a portion to a television 12 camera and another portion to a motion picture camera, which 13 is to photograph the image on film. The patent provides a 14 photomultiplier exposure sensing system immediately before the motion picture camera. Part of the light beam advancing 16 to the camera is directed by a second beam splitter onto an 17 imaging lens, through a mask and to a photomultiplier. The 18 photomultiplier senses the intensity of the light received, 19 determines the correct exposure required for an optimum photograph and adjusts the x-ray machine in response 21 thereto.
22 Yet another disclosure of interest is European 23 patent application EP-A-0157688 to Klausz which discloses a 24 system for the optimal placement of image enhancing filters.
The subject is exposed to x-ray radiation and the resultant 26 visible light image is passed through an image intensifier 27 to a TV camera. The image is recorded and projected back as 28 visible light onto the subject, typically a medical patient, 29 allowing better positioning and selection of filters to enhance the image. Once the position is correct and the 31 desired filters are in place, a second x-ray shot is taken 32 to produce the desired image on high-resolution film.
2 1 796 ~6 3 In the instant apparatus, X-rays are passed from a 4 conventional X-ray source through a biological subject (patient) in the usual manner. In most conventional X-ray 6 methods, the film is mounted in a cassette between two 7 layers of fluorescent material. When a short pulse of the 8 X-rays strike the fluorescent material, visible light is 9 produced in proportion to the intensity of the x-ray. This enhances the photographic effect on the X-ray film. (See 11 U.S. Patents Nos. 2,298,587 and 2,161,058, for example).
12 The present invention employs no film and only one 13 fluorescent layer. A mirror, mounted below the fluorescent 14 layer at an oblique angle, typically 45 degrees, to the path of the X-ray beam allows the X-rays to pass through the 16 mirror with their path unaltered, but reflects the brief 17 visible light image, created by the passage of X-rays 18 through the fluorescent layer, on a 90 degree path to the X-19 ray beam, thereby separating the visible light from the X-rays. This separation is important, because X-rays will 21 destroy most electronic detectors. The 45 degree alignment 22 of the mirror provides an equal path length from the image 23 plane (i.e. the fluorescent screen) to the detector plane 24 regardless of the position on the image plane, thus ensuring that a part of the image formed on the left of the 26 fluorescent screen will be sharply in focus at the same time 27 as a part from the right side. To minimize scattered 28 radiation, the mirror possesses an aluminum reflective layer 29 on the front, rather than the conventional silver backing, because aluminum is relatively transparent to X-rays.
31 Behind the reflective aluminum layer and glass substrate, 32 the mirror is coated with lead to absorb X-rays. An optical 33 receiving means, such as a CID (Charge Injection Device) 34 detector, in the form of a video camera disposed at the end of the 90 degree visible light path, registers the image.
36 The CID video camera is used rather than the generally 37 available CCD cameras because multiple frames may be stacked A
1 with a CID video camera. CCD cameras destroy the captured 2 image while reading it out and so do not allow for image 3 stacking. Without the CID, camera light levels may fall 4 below the usable threshold. While the use of a CID camera 5 is preferred in this device, a CCD camera of sufficient 6 sensitivity could also be used. A photocell detector near 7 the fluorescent screen registers the burst of visible light 8 and initiates capture of the image on the video camera by a 9 frame grabber. A frame grabber is essentially a circuit board mounted inside a computer which translates a video 11 image into a standard computer graphics file format such as 12 TIFF (Tagged Image File Format) for analysis and enhancement 13 by the computer. This board may be one of any number of 14 commercially available products and will incorporate image processing software as well as its ability to capture the 16 image. The use of a photocell coordinated frame grabber 17 obviates the need for more expensive techniques now being 18 introduced in the field of computed radiography such as 19 storage phosphors combined with laser scanning.
The whole apparatus, except for the computer, is 21 enclosed in a light proof, lead lined box. The height of 22 the box is determined by the size of the fluorescent screen, 23 as the mirror mounted beneath the fluorescent screen must be 24 of the same size. For example, an 8 inch by 10 inch screen requires a like sized mirror. With the mirror mounted at 45 26 degrees, the box height is the square root of 32 or 27 approximately 5.65 inches. The length of the box is 28 determined by the focal length of the camera in use. In one 29 example embodiment, a box length of approximately 3 feet is utilized.
31 Broadly stated then, the invention involves a 32 filmless x-ray apparatus for medical diagnostic imaging 33 comprising an x-ray source (1) for directing x-rays through 34 a subject (2), a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when 36 contacted by the x-rays, an oblique mirror (6) behind the 37 screen for reflecting the visible light radiation and A
__ 2179616 1 separating it from the x-rays, an optical receiving means 2 (7) and controlling/processing means (8,9), characterized 3 by: an x-ray source for directing a short pulse of x-rays 4 through a biological subject; a screen for producing a pulse of visible light radiation which is in the form of a visible 6 image; an optical receiving means, positioned in the path of 7 the reflected visible light radiation, for receiving the 8 pulse and producing a first signal indicative of the 9 received image; means (10) for sensing the first incidence of the emission of the pulse of light radiation by the 11 screen; and controlling/processing means, connected to 12 receive the first signal and to be activated by the sensing 13 means, for capturing the first signal in response to 14 activation by the sensing means, producing a digital representation of the captured image and producing the 16 digitized image on a viewable screen.
17 Experiments have shown that the image is captured 18 in the time taken to register a single frame of video, 19 typically 1/60 of a second. As photographic methods in radiology normally require exposures of 1/10 to 1 second, 21 the method of the present invention allows for either a 22 multiplicity of images to be captured in the same time 23 period or for the radiation exposure to be greatly reduced.
24 If the multiplicity of images is used, they may then be stacked together. The signal, or desirable part of the 26 picture, will be increased by the number of pictures 27 stacked. Any random noise however will increase only by the 28 square root of the number of pictures stacked. This yields 29 a signal to noise ratio improvement multiplier equal to the square root of the number of pictures stacked. If, for 31 example, four pictures of the same subject are stacked 32 together, the signal to noise ratio will improve by a factor 33 of two.
34 In current methods, an effect known as "heeling"
causes a variation of intensity from one end of the X-ray 36 image to the other due to the angle at which the X-rays are 37 emitted from the focal spot of the X-ray machine. This A
1 heeling effect must be allowed for in examining X-ray films.
2 In the inventive method, the heeling effect may be 3 electronically processed out at the image enhancement stage.
4 If a subject (patient) moves during exposure, as is common in veterinary medicine, the radiograph is useless 6 for diagnostic purposes using current methods. In the 7 method of the present invention, image processing software 8 allows for the removal of blur caused by linear motion. A
9 computer image can therefore be corrected, rather than repeating the exposure. This saves time and reduces patient 11 exposure in medical applications.
12 While an image obtained with a single video camera 13 may be adequate for most purposes, inevitably some 14 applications will require a higher resolution. To this end, a second embodiment of the invention uses not one, but many 16 video cameras. As suitable video cameras are commercially 17 available which measure only one or two inches in size, it 18 is feasible to mount as many as are required along a back 19 plane of a light proof box housing the imaging apparatus.
The desired resolution may then be obtained by forming a 21 composite of all the captured images, each of which will 22 have the same detailed spatial resolution.
23 These and various other advantages and features of 24 novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming 26 a part hereof. However, for a better understanding of the 27 invention, its advantages, and the objects obtained by its 28 use, reference should be made to the drawings which form a 29 further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described 31 preferred embodiments of the invention.
3 Figure 1 is a block diagram illustrating prior art 4 film type X-ray apparatus.
Figure 2 is a block diagram diagrammatically 6 illustrating a filmless X-ray apparatus according to a first 7 embodiment of the present invention.
8 Figure 3 is an exploded side elevational view of a 9 mirror component of the filmless X-ray apparatus of the present invention.
11 Figure 4 is a diagrammatic side elevational view 12 illustrating the housing, fluorescent screen, mirror and 13 video camera components of the filmless X-ray apparatus of 14 the present invention.
Figure 5 is a block diagram depicting a back plane 16 of a light proof box component of a filmless X-ray apparatus 17 according to a second embodiment of the invention.
21 As shown in Figure 1, a prior art film type X-ray 22 apparatus typically includes an X-ray source 1, which 23 directs X-rays X toward and through a subject 2, for example 24 a human, animal, or luggage at an airport security device.
The X-rays subsequently pass through a fluorescent 26 intensifying screen 3, for the purpose of producing light 27 radiation in the spectrum which can be recorded on a 28 photographic film plate 4. The photographic film 4 is 29 typically sandwiched between a first fluorescent intensifying screen 3 and a second fluorescent intensifying 31 screen 5 which includes a lead backing for preventing the 32 harmful emission of X-ray radiation.
33 According to a first embodiment of the present 34 invention, illustrated in Figures 2 and 4, a conventional X-ray source 1 emits a pulse of X-rays X toward and through a 36 subject 2. The X-rays travel through the subject 2 and a 37 conventional fluorescent intensifying screen 3. One A
1 suitable type of fluorescent intensifying screen is sold 2 under the designation DUPONT CRONEX QUANTA III (TM) and 3 distributed by Medtec Marketing Ltd., of Calgary, Alberta, 4 Canada, and many other sources. As a result of passage through fluorescent screen 3, X-rays and a visible component 6 of the light spectrum, indicated by the arrows designated 7 X+L, impinge upon a mirror 6 disposed at a 45 degree g included angle relative to the plane of the screen 3.
g As shown in Figure 3, the preferred mirror 6 for use in the present invention comprises a front surface 11 coated by an aluminum "silvering" layer 11 on a glass 12 substrate 12 provided with a lead backing layer 13.
13 After being reflected by the mirror 6, the visible 14 component of radiation L is directed toward a CID video camera. One suitable conventional form of CID video camera 16 for use in the present invention is available from CIDTEC of 17 Liverpool, New York, U.S.A. under the designation CIDTEC
lg model no. CID3710D solid state monochrome video camera. The 19 X-ray component of the radiation is not reflected by the mirror 6, but is rather absorbed by the lead backing 13 of 21 the mirror 6 (Figure 3), or by a lead lining 17 within a 22 light tight housing 14. The video signal produced by the 23 video camera 7 is directed by a conventional video coaxial 24 cable 16 or other suitable connector to a frame grabber circuit 8 operably connected to a computer 9, for example an 26 IBM compatible PC type computer. One example commercially 27 available frame grabber circuit is available from DataCube 28 of Peabody, Massachusetts, U.S.A., under the designation 29 DataCube QVC-423 and associated suitable image processing software is available from Sun Microsystems of Mountain 31 View, California, U.S.A., under the designation SunVision.
32 Alternative example image processing software is available 33 under the designation Aldus PhotoStyler (TM) in most retail 34 computer software stores.
In order to initiate and control the frame grabber 36 to capture an image from the video camera 7, a photocell 10 37 is positioned behind the fluorescent intensifying screen 3 1 and is operably connected to activate the fame grabber 8 2 upon emission of visible spectrum light from the screen 3 3 which impinges upon the photocell 10. Suitable conventional 4 control circuits may be utilized in association with the 5 frame grabber 8 to control the capture of single or multiple 6 images from the video camera 7 disposed on the back plane 15 7 of the housing 14.
g Figure 5 illustrates a modified back plane 15' 9 according to a second embodiment of the present invention, 10 in which a plurality of video cameras 7A, 7B, 7C, 7D, 7E, 11 7F, 7G, 7H, 7I, and 7J are mounted for the purpose of 12 capturing multiple images to achieve enhanced resolution.
7 The present invention is directed to apparatus for 8 the direct detection and computer enhancement of X-rays 9 which obviates the need for X-ray film, developers, fixers, and processing equipment associated with prior art X-ray 11 methods. The inventive apparatus provides faster image 12 processing than conventional methods and requires less 13 exposure for the subject. The inventive method and 14 apparatus has advantages over the new computed radiography techniques including simplicity and potential for low cost 16 application. This X-ray method and apparatus of the present 17 invention has applications in many fields including airport 18 security systems, industrial quality control, and medicine.
BACKGROUND OF THE INVENTION
22 For almost eighty years photographic films have 23 been used both to capture and display X-rays for diagnostic 24 purposes. (See Figure 1) . Only in the last ten years have any alternative methods of X-ray imaging started to appear.
26 Best known of these is the expensive and complicated CAT
27 scan system used in many hospitals. Less well known 28 filmless X-ray systems are now available which use a storage 29 phosphor device to capture the X-ray image. These so called image plates can be scanned by a laser beam a short time 31 later, causing the image plates to emit light proportional 32 to the intensity of X-rays to which they were previously 33 exposed. Such systems are also complicated and expensive, 34 requiring special laser equipment for the scanning stage.
They have however clearly demonstrated the great advantages 36 of filmless, or digital, X-ray pictures.
37 Digital recorded X-rays are superior to those 38 recorded with photographic film due to the greater dynamic 39 range of the digital recording system. Photographic methods A
2179616 .
1 allow approximately one order of magnitude dynamic range 2 whereas digital methods typically allow four orders of 3 magnitude. This advantage is only realized if the actual 4 capture of the X-ray image is digital. Merely scanning a previously recorded photographic X-ray will not do. In 6 addition to the inherent advantages of the increased dynamic 7 range, computer image processing techniques provide a wealth 8 of capabilities to study otherwise obscured details within 9 the image. Accordingly, the present invention proposes a filmless X-ray apparatus and method of using the same which 11 has all the advantages of digitally captured radiography and 12 in addition is mechanically very simple. This allows the 13 apparatus to be made at much lower cost than current 14 systems, making it suitable for installation in many more locations, e.g. radiology clinics outside of hospitals, 16 veterinary clinics, chiropractic clinics, etc. The 17 inventive apparatus will be a particular boon to remote 18 settlements where "tele-medicine" is practised, such as 19 northern Canada and Alaska, because it allows an X-ray image signal to be transmitted over phone lines without an 21 unacceptable loss of resolution.
22 Turning to the published prior art, a patent of 23 interest is PCT application W081/03594, filed by Brown et 24 al. This publication discloses an x-ray apparatus comprising: a source of x-rays for directing x-rays through 26 an object (mail); a fluorescent intensifying screen behind 27 the object, for producing visible light radiation when 28 contacted by the x-rays; a light source for producing 29 visible light radiation as a reference; a movable mirror, aligned with the screen, for reflecting the visible light 31 radiation and reflecting the x-rays, to separate them, in 32 one mode, and for passing the reference visible light 33 radiation, in the other mode; a video camera for scanning 34 the test and reference visible light images and producing signals indicative thereof; circuit and computer means for 36 capturing the test image and processing it to measure the 37 amounts of transmission through light and dark areas of the A
1 object and to compare these measurements against the 2 reference measurements to detect the presence of IED's (an 3 explosive device in the envelope).
4 Another patent of interest is U.S. patent 4,063,092 issued to Berdahl. This patent teaches a system 6 involving: an x-ray source for directing x-rays through a 7 biological subject; an electronic image intensifier behind 8 the subject, for amplifying an electrical signal produced by 9 the x-rays and in turn producing visible light radiation; a lens for collimating the light; a beam splitting mirror 11 which splits the light and directs a portion to a television 12 camera and another portion to a motion picture camera, which 13 is to photograph the image on film. The patent provides a 14 photomultiplier exposure sensing system immediately before the motion picture camera. Part of the light beam advancing 16 to the camera is directed by a second beam splitter onto an 17 imaging lens, through a mask and to a photomultiplier. The 18 photomultiplier senses the intensity of the light received, 19 determines the correct exposure required for an optimum photograph and adjusts the x-ray machine in response 21 thereto.
22 Yet another disclosure of interest is European 23 patent application EP-A-0157688 to Klausz which discloses a 24 system for the optimal placement of image enhancing filters.
The subject is exposed to x-ray radiation and the resultant 26 visible light image is passed through an image intensifier 27 to a TV camera. The image is recorded and projected back as 28 visible light onto the subject, typically a medical patient, 29 allowing better positioning and selection of filters to enhance the image. Once the position is correct and the 31 desired filters are in place, a second x-ray shot is taken 32 to produce the desired image on high-resolution film.
2 1 796 ~6 3 In the instant apparatus, X-rays are passed from a 4 conventional X-ray source through a biological subject (patient) in the usual manner. In most conventional X-ray 6 methods, the film is mounted in a cassette between two 7 layers of fluorescent material. When a short pulse of the 8 X-rays strike the fluorescent material, visible light is 9 produced in proportion to the intensity of the x-ray. This enhances the photographic effect on the X-ray film. (See 11 U.S. Patents Nos. 2,298,587 and 2,161,058, for example).
12 The present invention employs no film and only one 13 fluorescent layer. A mirror, mounted below the fluorescent 14 layer at an oblique angle, typically 45 degrees, to the path of the X-ray beam allows the X-rays to pass through the 16 mirror with their path unaltered, but reflects the brief 17 visible light image, created by the passage of X-rays 18 through the fluorescent layer, on a 90 degree path to the X-19 ray beam, thereby separating the visible light from the X-rays. This separation is important, because X-rays will 21 destroy most electronic detectors. The 45 degree alignment 22 of the mirror provides an equal path length from the image 23 plane (i.e. the fluorescent screen) to the detector plane 24 regardless of the position on the image plane, thus ensuring that a part of the image formed on the left of the 26 fluorescent screen will be sharply in focus at the same time 27 as a part from the right side. To minimize scattered 28 radiation, the mirror possesses an aluminum reflective layer 29 on the front, rather than the conventional silver backing, because aluminum is relatively transparent to X-rays.
31 Behind the reflective aluminum layer and glass substrate, 32 the mirror is coated with lead to absorb X-rays. An optical 33 receiving means, such as a CID (Charge Injection Device) 34 detector, in the form of a video camera disposed at the end of the 90 degree visible light path, registers the image.
36 The CID video camera is used rather than the generally 37 available CCD cameras because multiple frames may be stacked A
1 with a CID video camera. CCD cameras destroy the captured 2 image while reading it out and so do not allow for image 3 stacking. Without the CID, camera light levels may fall 4 below the usable threshold. While the use of a CID camera 5 is preferred in this device, a CCD camera of sufficient 6 sensitivity could also be used. A photocell detector near 7 the fluorescent screen registers the burst of visible light 8 and initiates capture of the image on the video camera by a 9 frame grabber. A frame grabber is essentially a circuit board mounted inside a computer which translates a video 11 image into a standard computer graphics file format such as 12 TIFF (Tagged Image File Format) for analysis and enhancement 13 by the computer. This board may be one of any number of 14 commercially available products and will incorporate image processing software as well as its ability to capture the 16 image. The use of a photocell coordinated frame grabber 17 obviates the need for more expensive techniques now being 18 introduced in the field of computed radiography such as 19 storage phosphors combined with laser scanning.
The whole apparatus, except for the computer, is 21 enclosed in a light proof, lead lined box. The height of 22 the box is determined by the size of the fluorescent screen, 23 as the mirror mounted beneath the fluorescent screen must be 24 of the same size. For example, an 8 inch by 10 inch screen requires a like sized mirror. With the mirror mounted at 45 26 degrees, the box height is the square root of 32 or 27 approximately 5.65 inches. The length of the box is 28 determined by the focal length of the camera in use. In one 29 example embodiment, a box length of approximately 3 feet is utilized.
31 Broadly stated then, the invention involves a 32 filmless x-ray apparatus for medical diagnostic imaging 33 comprising an x-ray source (1) for directing x-rays through 34 a subject (2), a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when 36 contacted by the x-rays, an oblique mirror (6) behind the 37 screen for reflecting the visible light radiation and A
__ 2179616 1 separating it from the x-rays, an optical receiving means 2 (7) and controlling/processing means (8,9), characterized 3 by: an x-ray source for directing a short pulse of x-rays 4 through a biological subject; a screen for producing a pulse of visible light radiation which is in the form of a visible 6 image; an optical receiving means, positioned in the path of 7 the reflected visible light radiation, for receiving the 8 pulse and producing a first signal indicative of the 9 received image; means (10) for sensing the first incidence of the emission of the pulse of light radiation by the 11 screen; and controlling/processing means, connected to 12 receive the first signal and to be activated by the sensing 13 means, for capturing the first signal in response to 14 activation by the sensing means, producing a digital representation of the captured image and producing the 16 digitized image on a viewable screen.
17 Experiments have shown that the image is captured 18 in the time taken to register a single frame of video, 19 typically 1/60 of a second. As photographic methods in radiology normally require exposures of 1/10 to 1 second, 21 the method of the present invention allows for either a 22 multiplicity of images to be captured in the same time 23 period or for the radiation exposure to be greatly reduced.
24 If the multiplicity of images is used, they may then be stacked together. The signal, or desirable part of the 26 picture, will be increased by the number of pictures 27 stacked. Any random noise however will increase only by the 28 square root of the number of pictures stacked. This yields 29 a signal to noise ratio improvement multiplier equal to the square root of the number of pictures stacked. If, for 31 example, four pictures of the same subject are stacked 32 together, the signal to noise ratio will improve by a factor 33 of two.
34 In current methods, an effect known as "heeling"
causes a variation of intensity from one end of the X-ray 36 image to the other due to the angle at which the X-rays are 37 emitted from the focal spot of the X-ray machine. This A
1 heeling effect must be allowed for in examining X-ray films.
2 In the inventive method, the heeling effect may be 3 electronically processed out at the image enhancement stage.
4 If a subject (patient) moves during exposure, as is common in veterinary medicine, the radiograph is useless 6 for diagnostic purposes using current methods. In the 7 method of the present invention, image processing software 8 allows for the removal of blur caused by linear motion. A
9 computer image can therefore be corrected, rather than repeating the exposure. This saves time and reduces patient 11 exposure in medical applications.
12 While an image obtained with a single video camera 13 may be adequate for most purposes, inevitably some 14 applications will require a higher resolution. To this end, a second embodiment of the invention uses not one, but many 16 video cameras. As suitable video cameras are commercially 17 available which measure only one or two inches in size, it 18 is feasible to mount as many as are required along a back 19 plane of a light proof box housing the imaging apparatus.
The desired resolution may then be obtained by forming a 21 composite of all the captured images, each of which will 22 have the same detailed spatial resolution.
23 These and various other advantages and features of 24 novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming 26 a part hereof. However, for a better understanding of the 27 invention, its advantages, and the objects obtained by its 28 use, reference should be made to the drawings which form a 29 further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described 31 preferred embodiments of the invention.
3 Figure 1 is a block diagram illustrating prior art 4 film type X-ray apparatus.
Figure 2 is a block diagram diagrammatically 6 illustrating a filmless X-ray apparatus according to a first 7 embodiment of the present invention.
8 Figure 3 is an exploded side elevational view of a 9 mirror component of the filmless X-ray apparatus of the present invention.
11 Figure 4 is a diagrammatic side elevational view 12 illustrating the housing, fluorescent screen, mirror and 13 video camera components of the filmless X-ray apparatus of 14 the present invention.
Figure 5 is a block diagram depicting a back plane 16 of a light proof box component of a filmless X-ray apparatus 17 according to a second embodiment of the invention.
21 As shown in Figure 1, a prior art film type X-ray 22 apparatus typically includes an X-ray source 1, which 23 directs X-rays X toward and through a subject 2, for example 24 a human, animal, or luggage at an airport security device.
The X-rays subsequently pass through a fluorescent 26 intensifying screen 3, for the purpose of producing light 27 radiation in the spectrum which can be recorded on a 28 photographic film plate 4. The photographic film 4 is 29 typically sandwiched between a first fluorescent intensifying screen 3 and a second fluorescent intensifying 31 screen 5 which includes a lead backing for preventing the 32 harmful emission of X-ray radiation.
33 According to a first embodiment of the present 34 invention, illustrated in Figures 2 and 4, a conventional X-ray source 1 emits a pulse of X-rays X toward and through a 36 subject 2. The X-rays travel through the subject 2 and a 37 conventional fluorescent intensifying screen 3. One A
1 suitable type of fluorescent intensifying screen is sold 2 under the designation DUPONT CRONEX QUANTA III (TM) and 3 distributed by Medtec Marketing Ltd., of Calgary, Alberta, 4 Canada, and many other sources. As a result of passage through fluorescent screen 3, X-rays and a visible component 6 of the light spectrum, indicated by the arrows designated 7 X+L, impinge upon a mirror 6 disposed at a 45 degree g included angle relative to the plane of the screen 3.
g As shown in Figure 3, the preferred mirror 6 for use in the present invention comprises a front surface 11 coated by an aluminum "silvering" layer 11 on a glass 12 substrate 12 provided with a lead backing layer 13.
13 After being reflected by the mirror 6, the visible 14 component of radiation L is directed toward a CID video camera. One suitable conventional form of CID video camera 16 for use in the present invention is available from CIDTEC of 17 Liverpool, New York, U.S.A. under the designation CIDTEC
lg model no. CID3710D solid state monochrome video camera. The 19 X-ray component of the radiation is not reflected by the mirror 6, but is rather absorbed by the lead backing 13 of 21 the mirror 6 (Figure 3), or by a lead lining 17 within a 22 light tight housing 14. The video signal produced by the 23 video camera 7 is directed by a conventional video coaxial 24 cable 16 or other suitable connector to a frame grabber circuit 8 operably connected to a computer 9, for example an 26 IBM compatible PC type computer. One example commercially 27 available frame grabber circuit is available from DataCube 28 of Peabody, Massachusetts, U.S.A., under the designation 29 DataCube QVC-423 and associated suitable image processing software is available from Sun Microsystems of Mountain 31 View, California, U.S.A., under the designation SunVision.
32 Alternative example image processing software is available 33 under the designation Aldus PhotoStyler (TM) in most retail 34 computer software stores.
In order to initiate and control the frame grabber 36 to capture an image from the video camera 7, a photocell 10 37 is positioned behind the fluorescent intensifying screen 3 1 and is operably connected to activate the fame grabber 8 2 upon emission of visible spectrum light from the screen 3 3 which impinges upon the photocell 10. Suitable conventional 4 control circuits may be utilized in association with the 5 frame grabber 8 to control the capture of single or multiple 6 images from the video camera 7 disposed on the back plane 15 7 of the housing 14.
g Figure 5 illustrates a modified back plane 15' 9 according to a second embodiment of the present invention, 10 in which a plurality of video cameras 7A, 7B, 7C, 7D, 7E, 11 7F, 7G, 7H, 7I, and 7J are mounted for the purpose of 12 capturing multiple images to achieve enhanced resolution.
13 It is to be understood, however, that even though 14 numerous characteristics and advantages of the present invention have been set forth in the foregoing description, 16 together with details of the structure and function of the 17 invention, the disclosure is illustrative only, and changes 18 may be made in detail, especially in matters of shape, size 19 and arrangement of parts within the principles of the invention to the full extent indicated by the broad general 21 meaning of the terms in which the appended claims are 22 expressed.
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A filmless x-ray apparatus for medical diagnostic imaging comprising: an x-ray source (1) for directing x-rays through a subject (2), a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when contacted by the x-rays, an optical receiving means (7) and controlling/processing means (8,9), characterized in that:
said intensifying screen (3) is a fluorescent intensifying screen for producing a pulse of visible light radiation which is in the form of a visible image;
an oblique mirror (6) is placed behind the screen for reflecting and separating the visible light radiation from the x-rays;
the optical receiving means is a high-resolution camera (7) positioned in the path of the reflected visible light radiation, for receiving the reflected light radiation;
a light-sensing means (10) is provided for sensing the first incidence of the emission of the pulse of visible light radiation by the intensifying screen (3) and emitting a triggering signal; and said controlling/processing means (8,9) is arranged for directing the camera (7) to receive and capture said first signal in response to the triggering signal.
2. The apparatus of claim 1 wherein:
the optical receiving means is a video camera which produces the first signal in a digital form and the controlling/processing means comprises a frame grabber circuit.
3. The apparatus of claim 1 wherein:
the optical receiving means is a plurality of video cameras.
4. The apparatus of claim 1, 2 or 3 wherein:
the mirror is associated with an aluminum reflective layer on the front and a lead layer on the back for absorbing x-rays passed through the reflective layer.
5. The apparatus of claims 1, 2 or 3 comprising:
a lead lined, light proof housing enclosing the screen, mirror, sensing means and optical receiving means.
6. A filmless x-ray method for high-resolution imaging comprising:
directing a short pulse of x-rays through a subject;
producing a pulse of light radiation in the visible spectrum which is in proportion to the intensity of the x-rays and is in the form of a visible image;
reflecting the pulse of light radiation at an oblique angle to separate it from the x-rays;
sensing the first incidence of the produced pulse of light radiation and emitting a triggering signal;
receiving the pulse of light radiation upon activation by the triggering signal and producing a signal indicative of the received image; and capturing the image signal to produce a digital representation of the image.
8. The filmless x-ray method as recited in claim 7 and applied to medical diagnostic imaging wherein:
the x-ray pulse is directed through a biological subject; and utilising the digital representation to produce the image in a viewable form on a screen.
9. The filmless x-ray method as recited in claim 8, wherein the visible image is captured with a high-resolution digital camera.
10. A filmless x-ray apparatus for high-resolution imaging comprising:
an x-ray source (1) for directing x-rays through a subject (2);
a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when contacted by the x-rays;
an oblique mirror (6) behind the screen for reflecting the visible light radiation and separating it from the x-rays;
a high-resolution camera (7) positioned in the path of the reflected visible light radiation, for receiving the reflected visible light radiation;
a light-sensing device for sensing the first incidence of the emission of the pulse of light radiation by the screen and emitting a triggering signal; and controlling/processing means (8,9) for directing the camera to emit a digital signal indicative of the image when activated by the triggering signal.
11. A filmless x-ray apparatus for adapting to existing x-ray apparatus, the x-ray apparatus having an x-ray source for directing x-rays through a subject, a fluorescent intensifying screen behind the object for producing visible light radiation when contacted by the x-rays, and an oblique mirror behind the screen for reflecting the visible light radiation and separating it from the x-rays, comprising:
a light-sensing means for sensing the first incidence of visible light radiation from the fluorescent intensifying screen and producing a triggering signal;
an optical receiving means, positioned in the path of the reflected visible light radiation, for receiving visible light radiation as an image and producing a signal indicative thereof; and image controlling/processing means connected to the light sensing means and the optical receiving means for activation by the triggering signal, capturing the image signal in response to activation by the triggering signal, and producing a digital representation of the image.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A filmless x-ray apparatus for medical diagnostic imaging comprising: an x-ray source (1) for directing x-rays through a subject (2), a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when contacted by the x-rays, an optical receiving means (7) and controlling/processing means (8,9), characterized in that:
said intensifying screen (3) is a fluorescent intensifying screen for producing a pulse of visible light radiation which is in the form of a visible image;
an oblique mirror (6) is placed behind the screen for reflecting and separating the visible light radiation from the x-rays;
the optical receiving means is a high-resolution camera (7) positioned in the path of the reflected visible light radiation, for receiving the reflected light radiation;
a light-sensing means (10) is provided for sensing the first incidence of the emission of the pulse of visible light radiation by the intensifying screen (3) and emitting a triggering signal; and said controlling/processing means (8,9) is arranged for directing the camera (7) to receive and capture said first signal in response to the triggering signal.
2. The apparatus of claim 1 wherein:
the optical receiving means is a video camera which produces the first signal in a digital form and the controlling/processing means comprises a frame grabber circuit.
3. The apparatus of claim 1 wherein:
the optical receiving means is a plurality of video cameras.
4. The apparatus of claim 1, 2 or 3 wherein:
the mirror is associated with an aluminum reflective layer on the front and a lead layer on the back for absorbing x-rays passed through the reflective layer.
5. The apparatus of claims 1, 2 or 3 comprising:
a lead lined, light proof housing enclosing the screen, mirror, sensing means and optical receiving means.
6. A filmless x-ray method for high-resolution imaging comprising:
directing a short pulse of x-rays through a subject;
producing a pulse of light radiation in the visible spectrum which is in proportion to the intensity of the x-rays and is in the form of a visible image;
reflecting the pulse of light radiation at an oblique angle to separate it from the x-rays;
sensing the first incidence of the produced pulse of light radiation and emitting a triggering signal;
receiving the pulse of light radiation upon activation by the triggering signal and producing a signal indicative of the received image; and capturing the image signal to produce a digital representation of the image.
8. The filmless x-ray method as recited in claim 7 and applied to medical diagnostic imaging wherein:
the x-ray pulse is directed through a biological subject; and utilising the digital representation to produce the image in a viewable form on a screen.
9. The filmless x-ray method as recited in claim 8, wherein the visible image is captured with a high-resolution digital camera.
10. A filmless x-ray apparatus for high-resolution imaging comprising:
an x-ray source (1) for directing x-rays through a subject (2);
a fluorescent intensifying screen (3) behind the subject for producing visible light radiation when contacted by the x-rays;
an oblique mirror (6) behind the screen for reflecting the visible light radiation and separating it from the x-rays;
a high-resolution camera (7) positioned in the path of the reflected visible light radiation, for receiving the reflected visible light radiation;
a light-sensing device for sensing the first incidence of the emission of the pulse of light radiation by the screen and emitting a triggering signal; and controlling/processing means (8,9) for directing the camera to emit a digital signal indicative of the image when activated by the triggering signal.
11. A filmless x-ray apparatus for adapting to existing x-ray apparatus, the x-ray apparatus having an x-ray source for directing x-rays through a subject, a fluorescent intensifying screen behind the object for producing visible light radiation when contacted by the x-rays, and an oblique mirror behind the screen for reflecting the visible light radiation and separating it from the x-rays, comprising:
a light-sensing means for sensing the first incidence of visible light radiation from the fluorescent intensifying screen and producing a triggering signal;
an optical receiving means, positioned in the path of the reflected visible light radiation, for receiving visible light radiation as an image and producing a signal indicative thereof; and image controlling/processing means connected to the light sensing means and the optical receiving means for activation by the triggering signal, capturing the image signal in response to activation by the triggering signal, and producing a digital representation of the image.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CA1993/000557 WO1994015255A1 (en) | 1992-12-23 | 1993-12-21 | Filmless x-ray apparatus and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2179616A1 CA2179616A1 (en) | 1994-07-07 |
| CA2179616C true CA2179616C (en) | 1999-08-24 |
Family
ID=4172996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002179616A Expired - Fee Related CA2179616C (en) | 1993-12-21 | 1993-12-21 | Filmless x-ray apparatus and method of using the same |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2179616C (en) |
| DE (1) | DE69330360T2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6483893B1 (en) | 1998-11-27 | 2002-11-19 | Wuestec Medical, Inc. | Digital high resolution X-ray imaging |
| US6339633B1 (en) | 1998-11-27 | 2002-01-15 | Wuestec Medical, Inc. | Automatic exposure initiation in a digital CCD camera x-ray imager |
| US6618494B1 (en) | 1998-11-27 | 2003-09-09 | Wuestec Medical, Inc. | Optical distortion correction in digital imaging |
| US6353657B1 (en) | 1998-11-27 | 2002-03-05 | Wuestec Medical, Inc. | Image redirection and optical path folding |
| CN109085735B (en) * | 2018-08-31 | 2024-04-09 | 中国工程物理研究院激光聚变研究中心 | Explosive foil flying piece X-ray dynamic imaging system |
-
1993
- 1993-12-21 CA CA002179616A patent/CA2179616C/en not_active Expired - Fee Related
- 1993-12-21 DE DE69330360T patent/DE69330360T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE69330360T2 (en) | 2001-11-15 |
| CA2179616A1 (en) | 1994-07-07 |
| DE69330360D1 (en) | 2001-07-19 |
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