CA1186815A - Image intensifier system and image intensifier unit therefor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An image intensifier system receives incident image conveying electromagnetic radiation or atomic particles ("incident beam") and provides to signal processing and video equipment signals from which the image conveyed by the incident beam can be constructed and displayed. The system includes a source of electromagnetic radiation or atomic particles and a table for supporting a patient who is undergoing medical treatment or examination having a patient support and a patient base defining a compartment that receives an image intensi-fier. The image intensifier unit includes an intensifier, a handle, and a targeting or aligning device for aligning the incident beam source with the intensifier.

Description

s 1 Field of the }nvention _ . . _ _ . . .
~ his invention relates generally to image intensi~ication and, more particularly, to a system for receiving electro-magnetic radiation or atomic particles that have passed throuyh a patient and providing to signal processing and video apparatus information from which that apparatus can construct an image of the portion of the patient through which the beam passed.

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Description of the Prior Art Generally, two types of devices have been used by medical lo personnel to produce images from radiation or atomic particles that have been passed through a patient - devices producing images on photographic film and image intensifier systems.
Although an image having good resolution can be obtained on light-sensitive film, the time required to process the film is relatively long and prohibitive for many app~ications. Further, a dynamic image of the patient under examination, which is highly desirable, cannot be obtained through the use of light-sensititvè film.

11~36~.5 Although an image of an object can be obtained quickly using conventional image intensifier systems, the resolution of the image (4 line pairs/mm) is unacceptable for many appli-cations. For example, the medical profession generally considers X ray images having only 4 line pairs/mm resolution to be unacceptable as an aid in examining the human body.
Therefore, conventional X ray image intensifier systems have not been heavily relied upon as a means for examining the human body.
Moreover, conventional X ray equipment, including equipment employing X ray sensitive film and X ray image intensifier systems has been large and cumbersome and, therefore, has placed severe restrictions on users of such equipment.
Finally, the resolution of a particular image intensifier system can be improved only by increasing the energy of the radiation or atomic particles passing through the patient or by moving the intensifier receiver closer to the patient. The former is acceptable as long as the energy level of the radi-ation or atomic particles remains below a level that is safe for the patient. The size of conventional intensifiers precludes the latter.
Accordingly, there exists a need for an image intensifier system that permits placement of the image intensifier unit of the system proximate the patient.

:118~ S

SUMMAR~ OF THE INVENTION
An image intensifier system is provided that receives electromagnetic radiation or atomic particles that have passed through a portion o a patient under examination ana transmits to signal processing and video equipment information from which that equipment can create a real-time image of the portion of the patient through which the radiation passed. The system permits placement of the image intensifier unit of the system pro~imate the patient and, therefore, permits medical personnel to pass radiation or atomic particles through the patient having a lower energy level than that used with conventional intensi-fiers.
The image intensifier system includes a source of electro-magnetic radiation or atomic particles, such as an X ray source, for directing a beam of electromagnetic radiation or atomic particles through the patient; a support, such as a surgical table, for supporting the patient in at least one position that enables medical personnel to treat or examine the patient having a patient support that is at least partially transmissive to the electromagnetic radiation or atomic particles and a base spaced apart from the patient support, and a compartment defined by the base and the patient support; and an image intensifier unit having a configuration that enables placement thereof within the compartment proximate the patient support. The source can be mounted on a structure, such as a wall or ceiling, or it can be portable. The image intensifier unit receives the electro-magnetic radiation or atomic particles from the source that pass through the patient and converts the passed radiation or ~6~ S

particles to information from which the signal processing and video equipment can create a real-time image of a portion of the patient. The image intensifier unit includes apparatus for receiving the passed radiation or particles, ~or converting the passed radiation or par-ticles - if necessary - to an image bearing medium dif~erent from the passed radiation or particles, and for amplifying the effect o the converted medium on the signal processing and video apparatus. In the preferred embodiment of the present invention, the converting apparatus includes a charge-coupled device.
The image intensifier unit includes a housing for enclosing the receiving, converting, and amplifying apparatus, and appa-ratus for aligning the source with the image intensifier.
Further, the unit can include a rod secured to the housing, a handle secured to the rod and disposed at a gO degree angle -thereto, an alignment device that provides a signal indicating l when the source and intensifier are aligned, and a second rod to! which the alignment device is secured and which is secured to ! the handle. Preferably, the second rod is constrained by the handle, during normal use of the intensifier unit, to move only toward or away from the intensifier.
In this application, the term "light" shall be construed to include X ray radiation, visible light, gamma ray radiation, ultraviolet light and infrared light. The term "MCP" shall be construed to mean a micro channel plate. The term "charge-coupled device" or "CCD" shall be construed to mean a self-scanning charge-coupled device. The term "charge-coupled device" or " CD" shall be construed to mean a conventional charge-coupled device with register areas protected from atomic particles when the CCD is used to detect atomic particles, any conventional CCD or a conventional CCD with memory capability when the CCD is used in an intensifier that processes X rays, and a conventional CCD with storage capabilicy when the CCD is used in the photon bombardment mode. Ther terms "incident beam'`
and "beam" shall be construed to mean incident light and particles. The term "particle" shall include photons and atomic particles. The term "electrical signal" shall include analog and digital signals.

BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description of the preferred embodiments can be understood better if reference is made to the accompanying drawings in which:
FIG. 1 is a sc~ematic diagram of an image intensifier that can be used with the present invention;
FIG. 2 is a schematic view of a portion of the scanning grid shown in FIG. l;
FIG. 3 is a schematic diagram of an image intensifier that can be used in the present invention that includes a silicon diode target and an electron beam gun as an electron detector;
FIG. 4 is a schematic diagram of an image intensi~ier that can be used in the present invention that includes a CCD as an electron or photon detector;
FIG.`5 is a schematic diagram of an image intensifier that can be used in the present invention that employs a potential field rather than an MCP for improving system resolution;

6~.5 FIG. 6 is a schematic diagram of the sensing, storage and register areas of one unit of a CCD that can be used in an image intensifier in the system of the present invention;
FIG. 7 is an electrical equivalent circuit of the sensing and storage areas of a CCD that can be used in an image intensi-fier of the present invention;
FIG. 8 is a perspective view showing the preEe,red embodiment of the present invention;
FIG. 9 shows the preferred embodiment of the support of the present invention and showing the radiation source and image intensifier of the present invention and the signal processing and video equipment graphically;
FIG. lO is an isometric view showing the preferred configu-ration of the image in~ensifier unit of the present invention;
FIG. il illustrates use of the image intensifier unit shown . in FIG. 9;
FIG. 12 is a top plan view of the image intensifier unit shown in FIGS. 9 and lO;
FIG. 13 is a side elevational view of the image intensifier unit shown in FIGS. 9 and lO; and FIG. 1~ illustrates the disposition of the components of an image intensifier that can be used in the image intensifier unit.

~ .5 D~TAILED DESC~IPTION OF THE PREFERRED EMBODIMENTS
FIGS. 8 and 9 depict an image intensifier system constructed according to the provisions of the present invention. FIGS. 10 and 11 through 13 show the configuration of an image intensifier unit that can be used in the present invention. FIG. 14 shows a possible arrangement of the components of an image intensifier that can be used with the system of the present inventionO FIGS. 1 through 7 show graphically the components of several image intensifiers suitable ~or use with the system of the present invention and illustrate the manner in which they function.

The Image Intensifier System FIG. 8 shows the pre~erred emboaiment o~ the present invention as it wouId be used in the operating room of a hospital. Image intensifier system lO0 includes X ray source 110, image intensifier unit 112 and surgical table 114. During use, intensifier 116 of intensifier unit 112 is placed within compartment 118 beneath the portion of patient 118 upon which operations are being conducted. For convenience, the system will be described as it is used to receive and process X rays.
X rays from source 110 pass through patient 118 and patient support 144 and striXe intensifier 116. Since an X ray beam is absorbed by material in proportion to the density of the mate-rial, the X ray beam striking intensifier 116 carries infor-mation related to the area of the body through which ~he X ray beam passed. Intensifier 116 receives the passed beam, converts the X rays to another information carrying medium and transmits .5 that medium to signal processing and video equipment 122 and 124 respectively. ~n image of the portion of the body through which the X ray beam from source 110 passed is shown on the video screen o~ video apparatus 124. The operation of the image intensifier 116 is described below in detail. It can be seen that an image of any portion o the body can be created simply by moving intensifier 116 within compartment 118.
Image intensifier unit 112 includes intensifier 116 which receives X ray radiation, converts the X rays and the infor-mation conveyed thereby to a form suitable for transmission to the signal processing and video equipment 122 and 124 respec-tively and amplifies the effect of that medium thereon. Inten-sifier unit 112 also includes a bar 126 fixed to intensifier 116 in any suitable fashion and a handle 128 secured to bar 126 at a right angle thereto. An alignment screen 130 includes a glass screen 132 and a frame 134 for supporting screen 132. Source 110 generates an alignment beam, such as a laser beam or a beam of visible light, which illuminates screen 132 where it passes therethrough and permits, thereby, alignment of intensifier 116 and source 110. Bar 136 is secured to frame 134 and handle 128 in any suitable manner. ~andle 128 and bars 126 and 136 are joined to restrict movement of bar 136 and target 130 toward or away from in-tensifier 116. Handle 128 can be any suitable known apparatus that can achieve such a result and can be a telescoping handle system, the two telescoping components of which can be secured in any position relative to each other by a bolt and wing nut assembly.

Surgical table 114 can be any suitable known surgical table having a compartment 118 for accepting intensifier 116.
However, a particularly suitable surgical table 114 is manu-factured by American 5terilizer Company of Erie, Pennsylvania and is sold under the trademark "2080 Series". Surgical table 114 includes a base 138, supporting column 140, and a patient base 142. Patient support 144 supports patient 118 and is positioned in spaced-apart relationship from patient base 142 by spacers 146. Spacers 146, patient base 142, and patient support 144 define compartment 118 which accepts intensifier 116.
Patient support 1~4 should be at least partially transmissive to X rays and preferably is completely transmissive thereto. It shGuld be noted that if the above-identified surgical table made by American Sterilizer Company is used as surgical table 114, pa~ient base is con~structed in movable sections to permit movement of one or more sections relative to the table to enable medical personnel to place patient 118 in a variety of positions to facilitate examination and treatment thereof. Such a table is described in a booklet published by American Sterilizer Company entitled "2080 Surgical Table Series".
To operate system 100, intensifier unit 112 is positioned with intensifier 116 disposed below the area of patient 118 to be examined. Source 110 is then positioned thereby to pass an X ray beam through the center of target 130. Screen 132 is illuminated ~here the alignment beam produced by source 110 passes therethrough. The illuminated area should be centered in screen 132 to ensure that all the information carried by the portion of the beam that passes through patient 118 is processed .S

by intensifier unit 112. Imaging information produced by inten-sifier unit 112 is carried by cable 148 to signal processing and video apparatus 122 and 12~, respectively. The nature of the information produced by intensifier unit 112 is discussed below. Signal processing and video equipment 122 and 124 can be any suitable such equipment known by workers in the art and can process the information produced by unit 116 in any known fashion.

The Intensifier And Its Operation FIG. 1 depicts an image intensifier lO that can be used as intensifier 116 of system lOO. Intensifier lO includes a scanning grid 24 and a photoanode 25 for detecting electrons 22. An incident beam of electromagnetic radiation 12 impacts scintillator 1~ thereby causing photons (not shown) to impact photocathode 16. Photocathode 16 can be any photocathode suitable for converting photons to photoelectrons. Scintillator 14 produces photons of a wavelength such that a miximum quantity of photoelectrons 18 are produced by photocathode 16 when it is impacted by a photon emitted by scintillator 14. The material comprising the scintillator can be matched to the type of beam to be detected. To detect X rays, gamma rays, infrared light, ultraviolet light, and atomic particles the scintillator should be made of any of the materials listed below:

10.

NaI (Tl) CsI (Tl) CsI ~Na) CaF2(Eu) 6Li(Eu) TlCl(BeI) CsF
BaF~
Bi4Ge3l2 Ki(Tl) CaW04 CdW04 If visible light is to be detected, the scintillator should be eliminated.
Photoelectrons-~18, emitted by photocathode 16, are accel~
~erated by an electric potential (not shown) established between photocathode 16 and a conventional MCP 20 and enter MCP 20. The electric field between photocathode 16 and MCP 20 can be approx-imately 300 volts. Preferably a 1 KV to 2 KV field is imposed across MCP 20 in which case MCP 20 multiplies the number of photoelectrons entering MCP 20 by 104 to 106. Secondary electrons 22, emitted from MCP 20, are accelerated by an electric field established between MCP 20 and a scanning grid 24 and travel toward scanning grid 24. The electric potential between MCP 20 and grid 24 can be approximately 300 volts. A
portion of scanning grid 24 is shown in FIG 2. Scanning grid 24 is composed of vertical leads 28 disposed in a position such that they form grid windows 32. Vertical leads 28 are .s electrically insulated ~rom horizontal leads 30 in any suitable fashion and are energized by a suitable electric source. A grld window 34 allows electrons 22 to pass through 24 (e.g. elec~rons 26 in FIG. 1) only if all four leds forming its boundaries are of the same polarity. If the leads forming a window 32 have two different polarities, the electrons will not be passed by the window but will be absorbed by the grid. It can be seen, therefore, that the beam of electrons 22 can be systematically scanned by permitting only one window (such as window 34) at a time to have boundaries of the same polarity and to change that window in a systematic fashion. Electrons 26 impact a conven-tional photoanode 25 which passes the information contained in each passed beam 26 relating to position and intensity of electrons 22 in any known fashion to data processing and video equipment (not shown) where an image is produced and displayed ~on a CRT. An electric field is established in any suita~le fashion for accelerating the passed electrons 26 toward the photoanode 25. That field can be 100 volts. An electric field of 1 KV - 2 KV can be set up across MCP 20 to facilitate the production of secondary electrons 22 by MCP 20.
FIG. 3 shows another image intensifier 40 suitable for use in the present invention. Intensifier 40 is similar to image intensifier 10 but detects electrons 22 b~ using silicon diode target 42 and electron beam gun 44 instead of a scanning grid and photoanode. Electrons 22 impact on target 42 and create charges in the target 42. A conventional electron beam gun 44 scans target 42 with an electron beam 46. The charges created by electrons 22 impacting on target 42 are dectected by beam 46 1~L3~ 5 and inormation relating to the location and intensity of the charges is transmitted in any known fashion to the data processing and video equipment from which an image is constructed and displayed. Again an electric field of approx-imately 1 KV should be established in any known fashion be-tween MCP 20 and target 42 to accelerate electrons 22 toward targe-t 42. An electric field of approximately 20 KV should be set up between target 42 and electron gun 44.
Another image intensifier 50 suitable for use in system 100 is shown in FIG. 4. Intensifier 50 is similar to image inten-sifiers 10 and 40, but detects electrons 22 by a self-scanning CCD 52 (see FIGS. 6 and 7). CCD 52 can be a device, such as a semiconductor chip, having sensing and register areas common to conventional CCDs but having the additional feature of storage areas for storing information sensed by the sensing areas, for passing such inform-ation to the register areas and for accep~ing image-conveying e~ternal analog electrical inputs from sources other than the sensing areas ~such as the register areas).
Alternately, CCD 52 can be a conventional CCD having only sensing and register areas. Sensing areas 54 detect electrons 22. Electrons 22 impacting sensing areas 54 create charges on the photo diode sensors 60 formed therein (see FIG. 7). These charges are transferred to the register areas 58 of the CCD. If a CCD having storage areas is desired, areas 58 of CCD 52 contain those storage areas. The equivalent circuit for each sensing and storage area is shown schematically in FIG. 7. When switch Sl is in position 1, sensor diode 60 is being charged by source VDD preparatory to detecting electrons 22, switch S2 can 13.

~ .5 be placed in position 2 to transfer information contained in the storage area to the register area through field effect transistor F2 or it can be in position 1 whereby no transfer takes place. When switch Sl is in position 2, switch S2 can be placed in position 2 and information from the register area can be read into the storage area through field effect transis-tor Fl. Also, when switch Sl is in position 2, sensing diode 60 can detect the presence of electrons 22. When switch Sl is in position 3, information is moved from sensing diode 60 to -the storage area. Capacitor Cl allows in~ormation to flow from the storage area to the register area nondestructively. The length of time during which information can be stored in the storage areas is limited only by the leakage rate of capacitor Cl. As long as capacitor Cl is charged, F2 can be triggered and infor-mation can be passed from the storage area to the register area. When image intensifier 50 is being used to create an image conveyed by light or particles, the sequence of switching is as follows:
1. Sl in position 1 (sensor charging), S2 in position 1

2. Sl in position 2 (sensor reading), S2 in position 1

3. Sl in position 3 (transfer from sensor to storage), S2 in position 1

4. S1 in position 1 (sensor charging), S2 in position 2 (transfer from storage to resister) (sensor ready)

5. Read out register areas to data processing and video equipment

6. Repeat steps 1., through 6.

11~ .S

FIG. 6 depicts schematically one unit 80 of the CCD array 52. Units 80 are bonded together in any suitable fashion to form CC~ array 52. The sensing areas of unit 80, Sl to SN, pass information to the storage areas, Ml to MN. Storage areas Ml to MN pass information to output register areas Rl to RN. The register areas are read out of "scanned" in serial fashion to the data processing and video equipment. The scanning sequence is as follows:
1. Move Rl to R2, R2 to R3,..., RN-l to RN, RN to data processing 2. Move R2 to R3,..., RN-l to RN, RN to data processing X. Move RN-2 to RN-l, RN-l to RN, RN to data processing X+l. Move RN-l to RN, RN to data processing X+2. Move RN to data processing.
Alternately, the information in register area RN is moved to register area Rl each time it is moved from RN to the data processing equipment. This feature not only allows unit 80 to retain the information read out from the register units, but allows information to be read into the register areas form an external buffer. Each time information is read from register area RN, it is combined with the corresponding information from all the register areas RN of the other array units 80 to obtain one line of the image. Preferably, since the storage area can be read nondestructively, after step 4 above, switch S2 can alternate between positions 1 and 2 until the sensing diode is charged and new information sensed thereby. The sequence of switching would be as ~ollows:
1. Sl in position 2 and S2 in position 1 2. Sl in position 3 and S2 in position 1 3. Sl in position 1 and S2 in position 2 ttransfer from storage to register area) . Read out register areas 5. S2 in position 1 6. S2 in position 2

7. Read out register areas

8. S2 in position 1

9. S2 in position 2

10 Read out ~egister are~:

X. S1 in position 2 and S2 in position 1 X+1. S2 in position 2 X+2. Read out register areas Y. Sl in position 3 and S2 in position 1 Y+l. Repeat steps 2 through Y~l.
This sequence ensures that the displayed image will appear continuous. It is preferable that nine readouts of the register area occur for every read by the sensing area. It can be seen that a similar sequence can be used when images are created from the external analog input.

,5 Moreover, it is preferable that register area 1 (see FIG.
6) be able to receive information Erom an external source. This would enable the register areas to accept information from an external source and read that lnformation into the storage areas via switch S2. An elec-tric field of 300 volts is established between MCP 20 and CCD 52.
A CCD 52 having sensing, storage and register areas can be constructed using any of the well-known procedures for producing chips. The CCD 52 can transfer information between the sensing and storage areas, the storage and register areas are among the register areas in the same fasion that information is transferred within conventional CCDs.
Another image intensifier 70 suitable for use in system 100 is shown in FIG. 5. Intensifier 70 is identical to image inten-sifier 50, except that a 20-27 ~V electric field is used to improve electron gain instead of an MCP.
It should be noted that visible ligh-t can be detected directly by CCD 52 and, accordingly, scintillator 14 or scintil-lator 14, photocathode 1~ and MCP 20 can be eliminated (see FIGS. 4 and 5).
The components of image intensifiers 10, 40, 50 and 70 that must be enclosed in a glass vacuum envelope can be so enclosed in any known fashion. Electrical communication between the enclosed components and external equipment can be accomplished in any Xnown fashion. The scintillator may be disposed inside or ou-tside the glass envelope. If it is desired to bombard the CCD with atomic particles, the CCD should be disposed inside ~he glass envelope. If it is desired to bombard the CCD with ~ a~.s photons, the CCD can be disposed inside or outside the glass envelope.
FIG. 14 shows the manner in which the components of image intensifier 70 can be housed within a plastic cover 148 and a glass envelope 150. The components of image intensifier 70 are contained in a vacuum 152. Vacuum 152 is necessary to maintain the energy level of electrons 18 and prevent scattering thereof, and accordingly loss of resolution of the imaye generated therefrom. The components shown in FIG. 14 within plastic cover 148 and glass envelope 154 can be fixed therein in any known fashion. Data buss 156 communicates with CCD outputs 158 and removes electrical current from in-tensifier 70 relating to the individual bits of information of the image conveyed by incident beam 12 generated by CCD 52. Ceramic substrate 154 acts as a support for CCD array 52 and CCD outputs 158.
The following iist sets forth preferred specifications for intensifiers 10, 40, 50 and 70:
Size of one channel of MCP - 40 microns Distance between photocathode and MCP - 1 to 2 mm Distance between photocathode and CCD - 10 to 20 mm Distance between MCP and CCD - 1 to 2 mm Distance between MCP and scanning grid - 10 mm Distance between scanning grid and photoanode - 10 mm Distance between MCP and silicon dlode target - 1 to 2 mm Distance between silicon diode target and electron beam gun - 10 to 15 inches Number of channels in MCP for 6 inch diameter sensor - 6 Size of each scanning grid window - 40 microns 18.

1 Amount of voltage on scanning grid leads - approximately 40 volts Potential across MCP to achieve gain of 106 - 2 KV.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for examining a patient using a beam of electromagnetic waves or atomic particles and providing signal processing and video apparatus with information from which an image of at least a portion of said patient can be constructed by said apparatus comprising in combination:
a source for creating said beam and for directing said beam through said patient;
a support for supporting said patient in at least one posi-tion that enables medical personnel to have access to said patient from all positions around said support, to examine or treat said patient, said support having a patient support that is at least partially transmissive to said beam and a base spaced apart from said patient support, said patient support and said base defining a compartment;
an image intensifier having a configuration that enables placement of said intensifier within said compartment proximate said patient support for receiving said beam from said source passing through said patient and for converting said passed beam to said information; and said image intensifier including means for receiving said passed beam, means for converting said passed beam to an image bearing medium different from said passed beam, and means for amplifying the effect of said medium on said signal processing and video apparatus.

2. The apparatus recited in claim 1 wherein said support can support said patient in a plurality of said positions.

3. The apparatus recited in claim 1 wherein said support is a surgical table.

4. The apparatus recited in claim 1 wherein said image bearing medium is electrical current.

5. The apparatus recited in claim 4 wherein said beam converting means includes a charge-coupled device.

6. The apparatus recited in claim 1 wherein said source directs X rays through said patient.

7. Apparatus for examining a patient using X rays and providing to signal processing and video apparatus information from which an image of at least a portion of said patient can be constructed by said apparatus comprising in combination:
a source of X ray radiation for directing a beam of X rays through said patient;
a surgical table for supporting said patient in a plurality of positions each of which enables medical personnel to have access to said patient from all positions around said table to examine or treat said patient, said table having a patient support that is at least partially transmissive to said X ray beam and a base spaced apart from said patient support, said patient support and said based defining a compartment;

an image intensifier having a configuration that enables placement of said intensifier within said compartment proximate said patient support for receiving said X rays from said source passing through said patient and for converting said passed X rays to said information; and said image intensifier including means for receiving said passed X rays, means for converting said passed X rays to a different image bearing medium from said X rays, and means for amplifying the effect of said medium on said signal processing and video apparatus.

22.