CN103227082B - X ray emitter and X ray production method - Google Patents
X ray emitter and X ray production method Download PDFInfo
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- CN103227082B CN103227082B CN201210563539.9A CN201210563539A CN103227082B CN 103227082 B CN103227082 B CN 103227082B CN 201210563539 A CN201210563539 A CN 201210563539A CN 103227082 B CN103227082 B CN 103227082B
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Abstract
A kind of X ray emitter, comprising: control circuit and multiple independent light path controlled, and each light path comprises: ordinary light source, for launching the light of particular range of wavelengths; Optical module, focuses on for the light launched ordinary light source; Photocathode, for photo-excited electron; Electron Beam Focusing structure, focuses on for the electron beam produced photocathode; Plate target, is subject to the bombardment of acceleration electronics and produces X ray by bremstrahlen; X ray exit window and common smooth entrance window, be located on vacuum tank; Vacuum tank, for encapsulating photocathode, Electron Beam Focusing structure and plate target.Above-mentioned X ray emitter can realize Multi-Beam X-Ray and be integrated in single X ray emitter, and it has high time resolution, able to programme, pulsed is launched, the size and shape of emitting area can change, the high pressure simple advantage relative to structure that easily access that difficulty is little, plate target easily dispels the heat.The present invention also provides a kind of X ray production method.
Description
[technical field]
The present invention relates to a kind of X ray emitter, particularly relate to a kind of X ray emitter for medical/industrial CT system and Micro-CT scanning and X ray production method.
[background technology]
X-ray imaging technology, namely utilize X ray can the character that decays of penetrating material carrying out according to the size of penetrator quality, the noninvasive imaging to internal structure of body is realized by the attenuation degree of detecting x-ray, it comprises X-ray technology (Radiography) and X ray computer tomography technology (Computed Tomography, CT).Wherein, CT technology is that ray projection by carrying out different visual angles to object is measured and obtains the imaging technique of object cross sectional information.CT system comprises the critical pieces such as X ray emitter, X-ray detector, frame, and wherein the generation device of X ray made by X ray emitter, is one of key core parts of CT system.
X-ray energy scope required for medical/imaging system such as industry CT and Micro-CT scanning is usually from tens kilo electron volts to hundreds of kilo electron volt, and the X ray emitter of its equipment adopts high-velocity electron beam to bombard the principle of plate target generation X ray usually.Namely in vacuum tank, the electronic beam current that a constant current of being launched by electron source is strong, and accelerated under the effect of high voltage electric field, bombardment plate target.Plate target is made up of the metal that atomic number is high usually, slows down, produce X ray by bremsstrahlung processes after electronics bombardment plate target.
The CT system of development is had higher requirement to the x-ray source as core component.Such as, the Novel static scanning computed tomography system recently grown up, requires that x-ray source has the feature of space, time transmitting able to programme.Conventional CT system adopts single x-ray source usually, relies on machinery to rotate, and namely passes through the rotation of the right rotation of x-ray source/detector or scanned object, realizes the X-ray scanning of different angles.And Novel static scanning computed tomography system uses that cover certain angular field of view, static X ray emitter, by the transmitting able to programme of the location and time of X ray, realize the acquisition of the X-ray transmission image of different visual angles.Static scanning CT system, due to without the need to mechanical rotation, reduces cost and the complexity of CT system.Meanwhile, x-ray source can be ignored switching time, so sweep time just equals the time for exposure, thus farthest shortens sweep time.This new CT system requirements X ray emitter has the structure of compacting, and namely requires that multiple independent X-ray beam controlled can effectively be integrated in single X ray emitter.
Meanwhile, CT system, in particular for the CT system of dynamic imaging (as cardiopulmonary imaging), in order to reduce the artifact produced because scanned object or patient produce due to motion, has very high requirement to the time resolution of x-ray source.CT system, for the consideration shortening sweep time and raising radiation dose utilance, also expects that x-ray source has higher time resolution.
The design of traditional X ray emitter mainly contains two kinds:
(1) traditional X ray emitter, adopts hot cathode as electron emission source, and by thermionic emission electron emission, electronics is subject to accelerating bombardment plate target and produces X ray.The filament that its negative electrode is normally made up of tungsten, produces heat when galvanization, and electronics is heated and obtains energy effusion.Electronics is under the acceleration of electric field, and bombardment plate target, produces X ray by bremsstrahlung processes.
(2) a kind of novel Flied emission X ray emitter of development in recent years, adopt cold cathode as electron emission source, namely negative electrode (such as carbon nano-tube film) is under the effect of high voltage electric field, electronics is produced by field emission mechanism, electronics is subject to accelerating bombardment plate target and produces X ray (as patent CN200710025641.2, field-emissive cathode X ray tube).This kind of X ray emitter adopts two pole formulas and three-pole structure usually.Two pole formula Flied emission X-ray tubes adopt negative electrodes to add the structure of anode, electron emission under the effect of the high voltage electric field that negative electrode provides at anode voltage, and obtain accelerating bombardment plate target thus produce X ray.Three-pole Flied emission X-ray tube adds independently electrode between a cathode and an anode, is called grid, for the electric field that applied field is launched.By opening or closing gate electric field, can momentary activation or interrupt the transmitting of electron beam, able to programme, the pulsed that can realize X ray are launched.Such radiographic source adopts certain focusing electrode for retraining electron beam usually, thus obtains less focal spot.Due to the existence of grid, being often limited to of this type of X-ray tube adopts anode to connect positive high voltage, earthed-cathode high pressure access design.
For the Traditional x-ray emitter adopting thermionic emission principle, because hot cathode has the own characteristics such as working temperature is high, power consumption is large, be difficult to multiple negative electrode to be integrated in single X ray emitter.Meanwhile, because hot cathode cannot suddenly heat up or cool, electronic beam current can not break-make at any time, and thus temporal resolution is limited, cannot carry out X ray that is able to programme, pulsed and launch.Due to the accurate exposure of X ray cannot be carried out, the very utilance of radiation dose also just cannot be obtained.
Field-transmitting cathode in Flied emission X ray emitter due to working temperature low, power consumption is little, is easily integrated in single X ray emitter by multiple negative electrode.Each negative electrode in the vacuum tank of X ray emitter is furnished with independent control electrode for realizing successively, programmable X ray transmitting.By the method for closing gate electric field corresponding to certain negative electrode or make certain cathode electrode unsettled, the transmitting of the electron beam of this negative electrode of instantaneous interruption, thus realize multiple negative electrode independently, successively, able to programme, pulsed X ray launches.Meanwhile, such X ray control mode, greatly limit the high pressure access way of x-ray source, is namely confined to adopt anode to connect positive high voltage, earthed-cathode design, makes high pressure access so more complicated.Meanwhile, due to plate target access high pressure, the difficulty of plate target heat radiation is considerably increased.
In addition, the size and shape in the cathode emission region of Flied emission X ray emitter is changeless, with requiring to change, cannot thus depend on the configuration variation of focusing electrode etc. to change the characteristic of focal spot.Meanwhile, this kind of X ray emitter often needs by grid to control the transmitting of X ray.More than each of which increases the complexity of Flied emission X ray emitter.
[summary of the invention]
In view of above-mentioned condition, the present invention proposes a kind of using the X ray emitter that can launch multiple beam X ray of photocathode as electron emission source.This invention can overcome Traditional x-ray emitter and be difficult to realize Multi-Beam X-Ray and be integrated in single X ray emitter, and temporal resolution is limited, cannot carry out the shortcomings such as able to programme, pulsed X ray transmitting; Meanwhile, also overcoming Flied emission x-ray source needs in vacuum tank, additionally insert control electrode and launches for controlling, and the size and shape in cathode emission region cannot control at any time, and high pressure access difficulty is large, the shortcoming of plate target not easy heat radiation and structure relative complex.
A kind of X ray emitter, comprise control circuit and multiple independent light path controlled, each light path comprises ordinary light source, optical module, common smooth entrance window, photocathode, Electron Beam Focusing structure, plate target, X ray exit window and vacuum tank;
Described control circuit, for controlling the operating state of the ordinary light source of described multiple light path;
Described ordinary light source, for launching the light of particular range of wavelengths;
Described optical module, focuses on for the light launched described ordinary light source;
Described common smooth entrance window, is located on described vacuum tank, and described common smooth entrance window is used for the light through described particular range of wavelengths;
Described photocathode, for photo-excited electron;
Described Electron Beam Focusing structure, focuses on for the electron beam produced described photocathode;
Described plate target, is subject to the bombardment of acceleration electronics and produces X ray by bremstrahlen;
Described X ray exit window, is located on described vacuum tank, and described X ray exit window is used for through X ray; And
Described vacuum tank, for encapsulating described photocathode, Electron Beam Focusing structure and plate target;
Wherein, the light that described ordinary light source is launched, after described optical module focuses on, be irradiated on described photocathode through described common smooth entrance window, described photocathode is subject to optical excitation and produces electronics; Described electron beam under the constraint of described Electron Beam Focusing structure, and bombards described plate target under the acceleration of high voltage electric field, makes described plate target produce X ray.
Compared to traditional X ray emitter, above-mentioned X ray emitter at least has the following advantages:
(1) above-mentioned X ray emitter is compared Traditional x-ray emitter and is had higher range of application and value.Above-mentioned X ray emitter utilizes photoelectric effect mechanism to produce X ray, can multiple independent X-ray beam be integrated in single x-ray source emitter, and adopt photocathode especially High-current-density Photocathodes as electron emission source, its electronic beam current can instantaneous break-make, X ray is launched there is high temporal resolution, independently, successively, able to programme, pulsed transmitting can be realized.Due to the accurate control that it can realize X-ray exposure, also just farthest radiation dose can be utilized.
(2) Flied emission X ray emitter compared by above-mentioned X ray emitter, has the relatively simple feature of project organization, can reduce costs.By changing the optical module outside vacuum tank, just can change the size and shape of the irradiation area of photocathode, thus indirectly change the size and shape of focal spot on plate target.Due to without the need to introducing focusing electrode and grid as Flied emission X ray emitter, greatly reduce complexity and the cost of X ray emitter.The control that Flied emission X ray emitter is launched to realize X ray, normal employing anode connects positive high voltage, earthed-cathode design, makes high pressure access so more complicated.Meanwhile, because plate target is in high voltage, the also greatly complicated difficulty of plate target heat radiation.Comparatively speaking, the present invention does not have such structural limitations, thus makes high pressure access and plate target dispel the heat convenient.
Wherein in an embodiment, described ordinary light source is laser generator, laser diode, fiber laser or high brightness LED.
Wherein in an embodiment, the particular value of described ordinary light source wavelength or particular range are determined by the constituent material characteristic of described photocathode, and the photoelectric conversion efficiency of the photocathode material making the photon of certain specific wavelength selected or particular range of wavelengths that X-ray tube can be made to adopt reaches maximum or is suitable for value.
Wherein in an embodiment, described photocathode adopts alkali metal, negative electron affinity III-V semiconductor compound or metal.
Wherein in an embodiment, the packing forms of described vacuum tank is glass packaging, cermet encapsulates or adopt the metal vacuum cavity that can maintain certain condition of high vacuum degree.
Wherein in an embodiment, the vacuum ranges of described vacuum tank is for being less than or equal to 10
-6millimetres of mercury is more than or equal to 10
-11millimetres of mercury.
Wherein in an embodiment, described common smooth incidence window is made up of optical glass.
Wherein in an embodiment, described optical glass is quartz glass, K9 glass, molybdenum glass or simple glass are made.
Wherein in an embodiment, described X ray exit window is made up of the material of low atomic number.
Wherein in an embodiment, the material of described low atomic number is metallic beryllium.
Wherein in an embodiment, the surface of described photocathode and horizontal direction angular range are for be less than or equal to 85 degree from being more than or equal to 5 degree, and the surface of described plate target and horizontal direction angular range are less than or equal to 15 degree for being more than or equal to 5 degree.
Wherein in an embodiment, be connected to high voltage between described photocathode and plate target, described high-tension high pressure connection connects positive high voltage for (1) anode, and negative electrode connects negative high voltage, (2) anode connects positive high voltage, minus earth or (3) plus earth, negative electrode connects negative high voltage.
Wherein in an embodiment, described Electron Beam Focusing structure has crowds around formula structure, and its current potential is equal with described photocathode or close, with the photoelectron of the form focus divergent of electrostatic lens.
Meanwhile, the present invention also provides a kind of X ray production method.
A kind of X ray production method, it adopts above-mentioned X ray emitter, it is characterized in that, described X ray production method comprises the steps:
Controlled the open and close of the ordinary light source of described multiple light path by described control circuit, thus indirectly realize the transmitting of the X ray in region corresponding to plate target, and then realize independently, successively, able to programme, the pulsed transmitting of Multi-Beam X-Ray; And/or
By changing the optical module outside described vacuum tank, change the size and shape of the irradiation area of described photocathode, thus change the size and shape of focal spot on described plate target; And/or
The light intensity magnitude of the ordinary light source of described multiple light path is controlled by described control circuit, thus the intensity of adjustment X ray.
[accompanying drawing explanation]
Fig. 1 is the control schematic diagram of the X ray emitter of embodiment of the present invention;
Certain light channel structure schematic diagram controlled separately that Fig. 2 is the emitter of X ray shown in Fig. 1.
[embodiment]
For the ease of understanding the present invention, below with reference to relevant drawings, the present invention is described more fully.Preferred embodiment of the present invention is given in accompanying drawing.But the present invention can realize in many different forms, is not limited to embodiment described herein.On the contrary, provide the object of these embodiments be make the understanding of disclosure of the present invention more comprehensively thorough.
It should be noted that, when element is called as " being fixed on " another element, directly can there is element placed in the middle in it on another element or also.When an element is considered to " connection " another element, it can be directly connected to another element or may there is centering elements simultaneously.Term as used herein " vertical ", " level ", "left", "right" and similar statement are just for illustrative purposes.
Unless otherwise defined, all technology used herein and scientific terminology are identical with belonging to the implication that those skilled in the art of the present invention understand usually.The object of term used in the description of the invention herein just in order to describe specific embodiment, is not intended to be restriction the present invention.Term as used herein " and/or " comprise arbitrary and all combinations of one or more relevant Listed Items.
Refer to Fig. 1 and Fig. 2, the X ray emitter 100 of embodiment of the present invention comprises control circuit 110, the ordinary light source group be made up of ordinary light source 120, optical module 120, vacuum tank 140, common smooth entrance window 150, photocathode 160, Electron Beam Focusing structure 170, plate target 180 and X ray exit window 190, as shown in Figure 1.This X ray emitter 100 logically can be point multiple independent " light path 101 " controlled, namely the ordinary beam of light sent by ordinary light source 120, irradiate certain region of photocathode 160, produce electron beam, target region on the plate target 180 that bombardment is corresponding, produces X-ray beam and through X ray exit window 190.Fig. 2 is the structural representation of certain independent optical paths 101.
In other words, X ray emitter 100 comprises control circuit 110 and multiple independent light path 101 controlled.Each light path 101 comprises ordinary light source 120, optical module 130, vacuum tank 140, common smooth entrance window 150, photocathode 160, Electron Beam Focusing structure 170, plate target 180 and X ray exit window 190.
Control circuit 110 is for the operating state of the control ordinary light source 120 of multiple light path 101.Ordinary light source 120 is for launching the light of particular range of wavelengths.Optical module 13 focuses on for the light launched ordinary light source 120.Common smooth entrance window 150 is located on vacuum tank 140, and common smooth entrance window 150 is for the light through particular range of wavelengths.Photocathode 160 is for photo-excited electron.Electron Beam Focusing structure 170 focuses on for the electron beam produced photocathode 160.Plate target 180 is subject to the bombardment of acceleration electronics and bremsstrahlung processes produces X ray.X ray exit window 190 is located on vacuum tank 140, and X ray exit window 190 is for through X ray.Vacuum tank 140 is for encapsulating photocathode 160, Electron Beam Focusing structure 170 and plate target 180.Wherein, the light that ordinary light source 120 is launched, after optical module 130 focuses on, be irradiated on photocathode 160 through common smooth entrance window 150, photocathode 160 is subject to optical excitation and produces electronics; Electron beam under the constraint of Electron Beam Focusing structure 170, and bombards plate target 180 under the acceleration of high voltage electric field, makes plate target 180 produce X ray.
It should be noted that, vacuum tank 140 in multiple light path 101, common smooth entrance window 150, photocathode 160, Electron Beam Focusing structure 170, plate target 180 and X ray exit window 190 can individually be arranged, also one can be shared, such as, the photocathode 160 of multiple light path 101 is a monoblock photocathode.
The working mechanism of this X ray emitter 100 is as follows, can realize Multi-Beam X-Ray independently, successively, able to programme, pulsed X ray launches: by control circuit 110 control certain light path 101 ordinary light source 120 send the light beam of specific wavelength or a wavelength range, this light beam carries out reflecting via optical module 130, after focusing etc., by the common smooth entrance window 150 on vacuum tank 140, enter vacuum tank 140 and be radiated on photocathode 160.Photocathode 160 adopts photocathode 160 material with high current density characteristic, after photocathode 160 is subject to this light beam irradiates, electronics is launched by photoelectric effect mechanism, electronic beam current is under the constraint of Electron Beam Focusing structure 170, simultaneously under the effect of the high voltage electric field of plate target 180 generation, accelerated and bombarded plate target 180.Slow down after electronics bombardment plate target 180, produce X ray by bremsstrahlung processes, last X ray is exported outside vacuum tank 140 by X ray exit window 190.Ordinary beam of light, according to the control principle of ordinary light source 120, controls by necessarily tying control circuit 110.By the effect of control circuit 110, the light intensity magnitude of ordinary light source 120 can be adjusted, thus the intensity of Indirect method X ray.By the control to circuit, just can control instantaneous unlatching or the closedown of ordinary light source 120, make photocathode 160 be activated or close, thus indirectly control by the unlatching of the X ray of the generation of plate target 180 or closedown.By control circuit 110 realize independently, successively, the unlatching of ordinary light source in programmable multiple light path 101 or closedown, just indirectly can realize the transmitting of the X ray of target region corresponding on plate target 180, thus finally realize independently, successively, able to programme, the pulsed X ray transmitting of Multi-Beam X-Ray.
Below illustrate the structure of all parts of above-mentioned X ray emitter 100:
Ordinary light source 120 can launch the light of particular range of wavelengths, and it can be but be not limited to laser generator, laser diode, fiber laser, high brightness LED etc.The particular value of the wavelength that ordinary light source 120 is launched or particular range are determined by the constituent material characteristic of photocathode 160, and the photoelectric conversion efficiency of photocathode 160 material that the photon namely selecting certain specific wavelength or particular range of wavelengths can make X-ray tube adopt reaches maximum or is suitable for value.Photoelectric conversion efficiency reaches great situation and includes but not limited to following situation: when photocathode 160 adopts alkali metal, He-Ne laser or Ar ion laser can be adopted as ordinary light source 120; When photocathode 160 adopts negative electron affinity III-V semiconductor compound, available frequency multiplication aluminium-yttrium aluminium garnet laser is as ordinary light source 120; When photocathode 160 is metal, available KrF excimer laser or ArF excimer laser are as ordinary light source 120.For the situation of the photocathode 160 enumerated above, also can with the laser diode of respective wavelength peak value or fiber laser or high brightness LED as common alternative laser as ordinary light source 120, thus reach photocathode 160 electron emission density of needs.
Photocathode 160, Electron Beam Focusing structure 170, plate target 180 are encapsulated in the vacuum tank 140 of a high vacuum.Vacuum tank 140 can take the Vacuum Package form such as glass packaging, cermet encapsulation, also can adopt the metal vacuum cavity that can maintain certain condition of high vacuum degree.The vacuum degree of vacuum tank 140 is determined according to the characteristic of photocathode 160, and vacuum ranges can for being less than or equal to 10
-6millimetres of mercury is more than or equal to 10
-11millimetres of mercury.
Common smooth entrance window 150 is installed on vacuum tank 140, and it is made up of the material that can pass through the common light of specific wavelength, can be but be not limited to quartz glass.X ray exit window 190 mouthfuls is installed on vacuum tank 140, and it is made up of the material of high X ray penetrance, can be but be not limited to metallic beryllium.
Photocathode 160 and plate target 180 all tiltable are arranged, and such as, photocathode 160 surface is less than or equal to 85 degree with horizontal direction angular range for being more than or equal to 5 degree, and plate target 180 surface is less than or equal to 15 degree with horizontal direction angular range for being more than or equal to 5 degree.
Photocathode 160 can be made up of the photocathode material of large emission density, and the material selecting electrical and thermal conductivity performance good is as substrate.Photocathode 160 material can be selected but be not limited to the compound semiconductor materials that is made up of alkali metal, if any antimony cesium compound (Cs3-Sb), and two base material (K2-Cs-Sb) and polybase material (Na-K-Cs-Sb); Negative electron affinity III-V semiconductor compound, as GaAs (Cs, O2), GaAs (Cs, F); Metal material, as Al, Cu, Zn, Na, Cu-Be, stainless steel 304 etc.
Electron Beam Focusing structure 170 is made up of conductive material, and conductive material includes but not limited to the material such as stainless steel, oxygen-free copper.Electron Beam Focusing structure 170 has crowds around formula structure, and its current potential is equal with photocathode or close, with the photoelectron of the form focus divergent of electrostatic lens, thus constraint electron beam, to obtain the focal spot of moderate size on plate target 180.
Plate target 180 is made up of the metal that atomic number is high, includes but not limited to the metals such as tungsten, molybdenum, copper, and by welding, technique and heat sink material (comprise and be not limited to oxygen-free copper, the alloy material) close contact such as to inlay to improve the rate of heat dissipation of plate target 180.
Be connected to high voltage between photocathode 160 and plate target 180, voltage range is different from 20 kilo electron volt to 500 kilo electron volts according to application demand.High voltage can adopt the one of following three kinds of high pressure connections: I. anode connects positive high voltage, and negative electrode connects negative high voltage; II. anode connects positive high voltage, minus earth; III. plus earth, negative electrode connects negative high voltage.
The light that ordinary light source 120 sends, carries out the process such as reflection, convergence of light beam through optical module 130, photocathode 160 is formed a certain size, the hot spot of shape.The irradiated region of photocathode 160, under the exciting of common light, photoelectric effect phenomenon occurs, and namely photon has certain probability to convert photoelectron to.The photoelectron of the irradiation area generation of photocathode 160, its current strength scope can from a few micromicroampere to hundreds of milliampere.Photoelectron focuses under the effect of Electron Beam Focusing structure 170, and draws acceleration under the effect of the electric field of anode electric field generation, and bombardment plate target 180 forms the focal spot of a certain size shape, and logical bremsstrahlung mechanism launches X ray.The X-ray beam sent from focal spot region penetrates from the X ray exit window 190 of vacuum tank 140.
Configured by adjustment optical module 130, just can change the size and shape of the irradiation area of photocathode 160 easily, thus indirectly change area size and the shape of focal spot on plate target 180.So just can when not changing the configuration in light source and vacuum tank 140, the parameter of the focal spot of adjustment X ray emitter 100.
Ordinary light source 120 can relatively easily be controlled by control circuit 110.By the effect of control circuit 110, the light intensity magnitude of ordinary light source 120 can be adjusted, thus the intensity of adjustment X ray.Instantaneous unlatching or the closedown of ordinary light source 120 easily can be controlled by control circuit 110.The instantaneous irradiation of ordinary beam of light or disappearance, by the instantaneous electron beam exciting or close photocathode 160, thus control indirectly by the unlatching of the X ray of the generation of plate target 180 or closedown.By control circuit 110 realize independently, successively, the unlatching of ordinary light source 120 or closedown in programmable ordinary light source group, just indirectly can realize the transmitting of the X ray in the region of plate target 180 correspondence, thus finally realize independently, successively, able to programme, the pulsed transmitting of Multi-Beam X-Ray.
It should be noted that, in the present embodiment, photocathode 160 can be reflecting light negative electrode, also can be transmission mode photocathodes.Plate target 180 can be the design of reflective plate target, also can be substituted with the design of transmission anode target.Plate target 180 can be fixed anode design, also can substitute with rotatable anode target.Electron Beam Focusing structure 170 can be add or replace with electrostatic lens (including but not limited to single or multiple focusing electrode), also can be add or replace with magnetic lens (including but not limited to permanent magnet or magnetic solenoid), also can be add or replace with the electromagnetic lens be made up of electrostatic lens and magnetic lens.
Compared to traditional X ray emitter, above-mentioned X ray emitter 100 at least has the following advantages:
(1) above-mentioned X ray emitter 100 is compared Traditional x-ray emitter and is had higher range of application and value.Above-mentioned X ray emitter 100 utilizes photoelectric effect mechanism to produce X ray, multiple independent X-ray beam is integrated in single x-ray source emitter, and adopt photocathode 160 especially High-current-density Photocathodes 160 as electron emission source, its electronic beam current can instantaneous break-make, X ray is launched there is high temporal resolution, independently, successively, able to programme, pulsed transmitting can be realized.Due to the accurate control that it can realize X-ray exposure, also just farthest radiation dose can be utilized.
(2) Flied emission X ray emitter compared by above-mentioned X ray emitter 100, has the relatively simple feature of project organization, can reduce costs.Above-mentioned X ray emitter 100, by changing the optical module 130 outside vacuum tank 140, just can change the size and shape of the irradiation area of photocathode 160, thus indirectly changes the size and shape of focal spot on plate target 180.Due to without the need to introducing focusing electrode and grid as Flied emission X ray emitter, greatly reduce complexity and the cost of X ray emitter 100.The control that Flied emission X ray emitter is launched to realize X ray, normal employing anode connects positive high voltage, earthed-cathode design, makes high pressure access so more complicated.Meanwhile, because plate target 180 is in high voltage, the difficulty that also greatly complicated plate target 180 dispels the heat.Comparatively speaking, the present invention does not have such structural limitations, thus makes high pressure access and plate target 180 dispel the heat convenient.
Meanwhile, the present invention also provides a kind of X ray production method.
A kind of X ray production method, it adopts above-mentioned X ray emitter, and X ray production method comprises the steps:
Controlled the open and close of the ordinary light source 120 of multiple light path 101 by control circuit 110, thus indirectly realize the transmitting of the X ray in the region of plate target 180 correspondence, and then realize independently, successively, able to programme, the pulsed transmitting of Multi-Beam X-Ray; And/or
By changing the optical module 130 outside vacuum tank 140, change the size and shape of the irradiation area of photocathode 160, thus change the size and shape of focal spot on plate target 180; And/or
The light intensity magnitude of the ordinary light source 120 of multiple light path 101 is controlled by control circuit 110, thus the intensity of adjustment X ray.
The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (12)
1. an X ray emitter, it is characterized in that, comprise control circuit and multiple independent light path controlled, each light path comprises ordinary light source, optical module, common smooth entrance window, photocathode, Electron Beam Focusing structure, plate target, X ray exit window and vacuum tank;
Described control circuit, for controlling the operating state of the ordinary light source of described multiple light path;
Described ordinary light source, for launching the light of particular range of wavelengths;
Described optical module, focuses on for the light launched described ordinary light source;
Described common smooth entrance window, is located on described vacuum tank, and described common smooth entrance window is used for the light through described particular range of wavelengths;
Described photocathode, for photo-excited electron, described time, is big current optical density negative electrode very;
Described Electron Beam Focusing structure, focuses on for the electron beam produced described photocathode, and described Electron Beam Focusing structure has crowds around formula structure, and its current potential is equal with described photocathode or close, with the photoelectron of the form focus divergent of electrostatic lens;
Described plate target, is subject to the bombardment of acceleration electronics and produces X ray by bremstrahlen;
Described X ray exit window, is located on described vacuum tank, and described X ray exit window is used for through X ray; And
Described vacuum tank, for encapsulating described photocathode, Electron Beam Focusing structure and plate target;
Wherein, the light that described ordinary light source is launched, after described optical module focuses on, be irradiated on described photocathode through described common smooth entrance window, described photocathode is subject to optical excitation and produces electronics; Described electron beam under the constraint of described Electron Beam Focusing structure, and bombards described plate target under the acceleration of high voltage electric field, makes described plate target produce X ray;
Described ordinary light source can launch the light of particular range of wavelengths, the particular value of described ordinary light source wavelength or particular range are determined by the constituent material characteristic of described photocathode, and the photoelectric conversion efficiency of the photocathode material making the photon of certain specific wavelength selected or particular range of wavelengths that X-ray tube can be made to adopt reaches maximum or is suitable for value; Described ordinary light source also adjusts its light intensity magnitude by described control circuit, thus the intensity of Indirect method X ray;
Described vacuum tank in multiple described light path, common smooth entrance window, photocathode, Electron Beam Focusing structure, plate target and X ray exit window share one.
2. X ray emitter as claimed in claim 1, it is characterized in that, described ordinary light source is laser generator, laser diode, fiber laser or high brightness LED.
3. X ray emitter as claimed in claim 1, is characterized in that, described photocathode adopts alkali metal, negative electron affinity III-V semiconductor compound or metal.
4. X ray emitter as claimed in claim 1, is characterized in that, the packing forms of described vacuum tank is glass packaging, cermet encapsulation or adopt the metal vacuum cavity that can maintain certain condition of high vacuum degree.
5. X ray emitter as claimed in claim 1, it is characterized in that, the vacuum ranges of described vacuum tank is for being less than or equal to 10
-6millimetres of mercury is more than or equal to 10
-11millimetres of mercury.
6. X ray emitter as claimed in claim 1, it is characterized in that, described common smooth incidence window is made up of optical glass.
7. X ray emitter as claimed in claim 6, it is characterized in that, described optical glass is quartz glass, K9 glass, molybdenum glass or simple glass.
8. X ray emitter as claimed in claim 1, it is characterized in that, described X ray exit window is made up of the material of low atomic number.
9. X ray emitter as claimed in claim 8, it is characterized in that, the material of described low atomic number is metallic beryllium.
10. X ray emitter as claimed in claim 1, it is characterized in that, the surface of described photocathode and horizontal direction angular range are for be less than or equal to 85 degree from being more than or equal to 5 degree, and the surface of described plate target and horizontal direction angular range are less than or equal to 15 degree for being more than or equal to 5 degree.
11. X ray emitters as claimed in claim 1, it is characterized in that, high voltage is connected between described photocathode and plate target, described high-tension high pressure connection connects positive high voltage for (1) anode, negative electrode connects negative high voltage, (2) anode connects positive high voltage, minus earth or (3) plus earth, negative electrode connects negative high voltage.
12. 1 kinds of X ray production methods, it adopts the X ray emitter as described in any one of claim 1 ~ 11, it is characterized in that, described X ray production method comprises the steps:
Controlled the open and close of the ordinary light source of described multiple light path by described control circuit, thus indirectly realize the transmitting of the X ray in region corresponding to plate target, and then realize independently, successively, able to programme, the pulsed transmitting of Multi-Beam X-Ray; And/or
By changing the optical module outside described vacuum tank, change the size and shape of the irradiation area of described photocathode, thus change the size and shape of focal spot on described plate target; And/or
The light intensity magnitude of the ordinary light source of described multiple light path is controlled by described control circuit, thus the intensity of adjustment X ray.
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| CN105794055B (en) * | 2013-12-05 | 2019-07-30 | Asml荷兰有限公司 | Electron injector and free electron laser |
| CN105185673B (en) * | 2015-07-15 | 2018-09-04 | 国家纳米科学中心 | A kind of photoinduced electron emission source and its manufacturing method, electron emitting device |
| CN106409639B (en) * | 2016-12-15 | 2019-03-01 | 清华大学 | Film photocathode distribution X-ray generator and the CT equipment with the device |
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| FR3069098B1 (en) * | 2017-07-11 | 2020-11-06 | Thales Sa | COMPACT IONIZING RAY GENERATOR SOURCE, ASSEMBLY INCLUDING SEVERAL SOURCES AND PROCESS FOR REALIZING THE SOURCE |
| GB2565138A (en) * | 2017-08-04 | 2019-02-06 | Adaptix Ltd | X-ray generator |
| EP3817027A4 (en) * | 2018-06-29 | 2021-08-18 | Nanovision Technology (Beijing) Co., Ltd. | Scanning-type x-ray source and imaging system therefor |
| CN109730706A (en) * | 2019-01-28 | 2019-05-10 | 深圳市纳诺艾医疗科技有限公司 | A kind of local second-order fluorescence radiation X bulb |
| CN113571396A (en) * | 2021-07-12 | 2021-10-29 | 无锡日联科技股份有限公司 | Target window separation double-vacuum-chamber transmission X-ray tube |
| CN114093736A (en) * | 2021-11-18 | 2022-02-25 | 武汉联影医疗科技有限公司 | Electron emission device and X-ray tube |
| CN117733305B (en) * | 2024-02-20 | 2024-04-26 | 四川华束科技有限公司 | Sealed-off type electron gun and non-vacuum electron beam welding robot |
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