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WO2012168218A2 - Détecteur de rayonnement et système d'imagerie - Google Patents

Détecteur de rayonnement et système d'imagerie Download PDF

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Publication number
WO2012168218A2
WO2012168218A2 PCT/EP2012/060564 EP2012060564W WO2012168218A2 WO 2012168218 A2 WO2012168218 A2 WO 2012168218A2 EP 2012060564 W EP2012060564 W EP 2012060564W WO 2012168218 A2 WO2012168218 A2 WO 2012168218A2
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WO
WIPO (PCT)
Prior art keywords
microchannel plate
radiation
photocathode
scintillator
radiation detector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2012/060564
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German (de)
English (en)
Other versions
WO2012168218A3 (fr
Inventor
Harry Hedler
Timothy Hughes
Martin Spahn
Stefan Wirth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of WO2012168218A2 publication Critical patent/WO2012168218A2/fr
Publication of WO2012168218A3 publication Critical patent/WO2012168218A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/28—Measuring radiation intensity with secondary-emission detectors

Definitions

  • the present invention relates to a radiation detector, with the aid of an electromagnetic radiation, insbeson ⁇ particular X-ray or gamma radiation can be detected.
  • the invention further relates to an imaging system comprising such a radiation detector.
  • Imaging systems of medical technology now play ei ⁇ ne increasingly important role.
  • Such systems are used to generate two- or three-dimensional image data of organs and structures of the human body, which can be used, for example, to diagnose disease causes, to perform operations and to prepare therapeutic measures.
  • the image data can be generated on the basis of measurement signals which are obtained with the aid of a radiation detector.
  • CT Computertomo ⁇ chromatography systems
  • the body or a body portion of a patient to be examined is irradiated by means of X-radiation, which is generated by a radiation source.
  • the unabsorbed, transmitted radiation component is detected by a detector.
  • Radionuclide imaging as used in positron emission tomography (PET) systems and single photon emission computer tomography (SPECT) systems.
  • PET positron emission tomography
  • SPECT single photon emission computer tomography
  • the patient to be examined is injected with a radiopharmaceutical which generates gamma quanta either directly (SPECT) or indirectly (PET) by emitting positron.
  • the gamma radiation is detected with a corresponding radiation detector.
  • Detectors which can be used for the energy-resolved detection or "counting" of radiation quanta can work according to different measuring principles: Radiation detection can take place either directly, ie by direct conversion of the radiant energy into electrical energy, or in an indirect manner As a rule, a so-called scintillator is used, which is excited under the action of a radiation to be detected and emits the excitation energy while emitting a low-energy electromagnetic radiation, only the radiation emitted by the scintillator
  • Radiation is converted into electrical measuring signals.
  • areal constructed detectors are, for example, in M. Spahn,
  • Photons charge carriers or electrons generated, which are multiplied avalanche-like.
  • Each photodiode is connected to a resistor (so-called “quenching resistor”), and is usually operated in the so-called Geiger mode above the breakdown voltage.
  • Photomultiplier may comprise up to 1000 photodiodes per mm 2 surface, wherein the individual photodiodes may have dimensions in the range between 20 and 100 ym.
  • a disadvantage of silicon photomultipliers is that only part of the total area available for irradiation acts as a sensitive or "active" area. can be used. The reason for this is that there also exist insensitive regions between the active or radiation-sensitive regions, in which resistors and signal lines or wiring structures are arranged. Therefore, a silicon photomultiplier has a relatively low ratio of active area to (irradiated) total area, which is also referred to as "fill factor.” Typically, the fill factor of a silicon photomultiplier is only about 60%. Photomultipliers consequently result in an impairment of the efficiency of the associated radiation detectors.
  • a further disadvantage is the noise that occurs during operation of silicon photomultipliers, which is superimposed on the actual measurement signals. This means that an accurate measurement can be impaired, in particular if a low radiation intensity is present. Also, silicon photomultipliers have a relatively high dark count, that is, signal generation occurs even without irradiation.
  • MCP microchannel plates
  • an electrical voltage applied along the channels is generated, thereby accelerating incoming electrons within the channels can be multiplied by collisions with the Ka ⁇ nalcommunn.
  • a use of a microchannel plate in connection with an image intensifier is described for example in US 2009/0256063 Al.
  • the object of the present invention is to provide a solution for improved radiation detection in the medical field.
  • a radiation detector which has a scintillator for generating an electromagnetic radiation under the action of an incident radiation and a photocathode for generating electrons under the action of the electromagnetic radiation generated by the scintillator.
  • the radiation detector further comprises a microchannel plate having a plurality of channels for multiplying the electrons generated by the photocathode, and detecting means for detecting the electrons multiplied by the microchannel plate.
  • the scintillator un ⁇ ter action of a to be detected incident radiation in particular X-ray or gamma radiation
  • the excitation energy by emission of a corresponding electromagnetic radiation (particularly visible or ultraviolet light) again.
  • the light emitted from the Szintilla ⁇ tor radiation results in the photocathode to the pho ⁇ toelektrischen generation and emission of electrons (Photo valued. Primary electrons), which are accelerated in the channels of the microchannel plate and thereby (multiple) at the Ka nalstructure, releasing further electrons ( Secondary electrons) can abut.
  • the other electrons can also be accelerated within the channels, and successively dissolve further electrons through wall joints.
  • the electrons multiplied in this way are detected by the detection device, whereby a corresponding output signal can be generated.
  • the radiation detector operating in accordance with this process chain can have a (relatively) linear detection behavior, ie the number or total charge of the electrons detected by the detection device is (substantially) proportional to the energy deposited in the scintillator an associated radiation quantum.
  • Another advantage is that the radiation detector compared to a conventional detector with silicon photomultiplier (substantially) lower noise and a lower dark rate can have. This is due to the fact that without radiation of the Szin- tillators no electrons in the photocathode generates the ⁇ and consequently (substantially) does not take place Elektronenvervielfachfachung in the microchannel plate.
  • the radiation detector can also be manufactured in a simple, cost-effective manner and with compact dimensions.
  • the micro-channel plate used for the electron multiplication can be formed with a high porosity, so that the microchannel plate has a high fill factor (ratio of active area to total area), and as a result of which the Strahlunsgdetektor ⁇ has a high efficiency and a high efficiency.
  • the fill factor of the microchannel ⁇ plate may be (substantially) higher than in a conventional silicon photomultiplier.
  • an "activated" channel of the microchannel plate, in which a secondary electron multiplication will occur, or having taken place ⁇ has the stands, initially for a period of time, also known as “dead time” refers to not direct coming from the photocathode electron multiplication of a WEI to Ver ⁇ addition.
  • the reason for this is that the release of electrons in the course of electron multiplication requires a recharging of the relevant channel.
  • the scintillator, the photocathode, the microchannel plate and the detection device are arranged one above the other.
  • Strahlungsde ⁇ tektors can be realized.
  • the photo-cathode is disposed on one side of the microchannel plate, wel ⁇ surface facing the scintillator.
  • the photocathode further has openings over which channels of the microchannel plate are exposed.
  • the photoka ⁇ Thode a reflective working, so-called cathode is Reflexionsphoto- which emits electrons from the side on which the light coming from the scintillator ⁇ electro-magnetic radiation impinges.
  • the electrons emitted by the photocathode can pass through the openings of the photocathode into the channels of the microchannel plate, and thereby generate or release further electrons.
  • the photocathode may have a relatively large thickness or layer thickness. This ver ⁇ connected is a high efficiency in the realized by means of the implementation of the photoka ⁇ Thode coming from the scintillator electromagnetic radiation into electrons.
  • microchannel plate on the side opposite the scintillator on elevations between the channels which is a decreasing or tapering in the direction of the scintillator
  • the reflective working photocathode of the radiation detector is arranged. Due to the elevations, the photocathode has a relatively large surface area, which further promotes efficient conversion of the radiation of the scintillator into electrons.
  • the microchannel plate comprises a semiconductor material, preferably silicon.
  • a semiconductor material preferably silicon.
  • Sili ⁇ zium can be achieved that the time period for recharging an unloaded in the course of electron multiplication which channel is relatively small.
  • the Mikrokanalplat ⁇ te can be prepared in a simple manner, in particular by means of a Lithography ⁇ phical patterning and etching process, ⁇ the.
  • a semiconductor material of silicon or the microchannel plate may also use other materials umfas ⁇ sen. In particular, it may be provided to form a coating with high secondary electron emission within the channels.
  • the high melting temperature of silicon (about 1420 ° C) provides with regard to the above-described direct arrangement of the photocathode to the microchannel plate further the Mög ⁇ friendliness, the photocathode by means of techniques Hochtemperaturtech ⁇ form.
  • a large number of different materials are available for the photocathode.
  • a multiplicity of different sintillator materials may also be considered for the scintillator, it being possible for a photocathode adapted thereto to be provided depending on the particular scintillator material selected (or on the wavelength or the wavelength range of the respectively produced scintillating radiation).
  • the channels of the microchannel plate are tilted relative to a normal of a plane predetermined by the microchannel plate.
  • the microchannel plate in addition to at least one disposed within the microchannel plate electrode for Elektronenvervielfa ⁇ monitoring.
  • the microchannel plate electrode for Elektronenvervielfa ⁇ monitoring By such an electrode, for which a mate ⁇ rial be provided with high secondary electron emission can, the release of additional electrons can be effected.
  • the detection device used to detect the electrons multiplied by the microchannel plate preferably has a plurality of electrodes. In this way, it is possible to detect not only the energy of a radiation quantum interacting with the scintillator, but also the location of the interaction. It can be provided that a single electrode of the detecting means is zugeord ⁇ net each having a number of channels of the microchannel plate, and therefore to the "pick-up" and the multiplied electrons is used herein, "collection”.
  • the detection device is designed in the form of an application-specific integrated circuit. As a result, processing or partial evaluation of a measurement signal based on the detected electrons can already take place at the location of the detection device.
  • the radiation detector further comprises an intermediate connection element arranged between the scintillator and the microchannel plate, which is permeable to the electromagnetic radiation generated by the scintillator.
  • an intermediate connecting element which serves as entrance or entrance window, can be used for sealing or closing one side of the microchannel plate, and thus for providing a vacuum enabling the movement of the electrons in the channels.
  • the possibility of arranging the photocathode on one of the micro-channel plate envisagelie ⁇ constricting side of the intermediate connecting member.
  • the photocathode provides a semitransparent parente photocathode or a transmission photocathode, which operates in a transmissive manner.
  • the electrons are emitted from the side of the photocathode, which is opposite to the irradiated side.
  • an imaging system which comprises a radiation detector according to one of the embodiments described above, and in which therefore also the advantages described above can come to light.
  • Such an imaging system can be, for example, an X-ray or computed tomography system, or else a positron emission tomography or a sin ⁇ gle photon emission computer tomography system.
  • the above-described detector structure consisting of scintillator, photocathode, microchannel plate and detection device each represents a single detector element or a "pixel" of an associated detector, and that a plurality of such detector elements or “Pixels" are arranged in particular flat and / or (partially) circular next to each other.
  • Figure 1 is a schematic representation of an X-ray system
  • Figure 2 is a schematic perspective view of a
  • Detector element a schematic side view of the detec torelements ⁇ with an illustration of its operation
  • Figure 4 is a schematic plan view of the Detektorele ⁇ ment
  • FIG. 5 shows a schematic side view of a detector element with a microchannel plate, which has channels arranged in a tilted manner
  • Figure 6 is a schematic representation of a Detektorele ⁇ ment with one on a microchannel plate angeord- Neten photocathode layer;
  • Figure 7 is a schematic side view of a De ⁇ tektorelements having disposed within a Mikroka ⁇ nalplatte electrode layer;
  • Figure 8 is a schematic side view of compo nents ⁇ a further detector element
  • Figure 9 is a schematic side view of a de- tektorelements, which is composed of the Darge ⁇ presented in Figure 8 components;
  • Figure 10 is a schematic side view of compo nents ⁇ a further detector element.
  • Figure 11 is a schematic side view of a De ⁇ detector element, which is constructed from the ge Service ⁇ th in Figure 10 components.
  • an electromagnetic radiation in particular a high ⁇ energetic radiation such as X-rays or gamma radiation
  • known process processes from the field of semiconductor and detector technology can be carried out and conventional materials used, so that then only partially received.
  • the connection of detector components can also take place with the aid of customary bonding or bonding methods.
  • the detector concept described here is intended for use in connection with medical imaging systems. In such systems, based on measurement signals which are obtained with the aid of a corresponding radiation detector, two- or three-dimensional image data of organs and structures of the human body are generated.
  • FIG. 1 shows an X-ray system 110 which can be used for diagnostic and interventional imaging.
  • the x-ray system 110 comprises a radiation source 111 for emitting an x-radiation ("x-ray emitter”), and an associated surface-area detector 100 ("flat detector”) for detecting the radiation.
  • Radiation source 111 and detector 100 are mutually oppositely disposed at the ends of an egg-shaped holding means ⁇ 112th Due to this configuration, this arrangement is also referred to as "C-arm” or "C-arm”.
  • a patient to be examined is located on a patient table 117, and is disposed between the radiation source 111 and the detector 100.
  • the holding device 112 is further fastened to a robot 113 which is provided with a plurality of joints and with the aid of which the radiation source 111 and the detector 100 are set in a desired position with respect to the patient can be brought.
  • the X-ray system 110 further comprises a control or evaluation device 114. This is connected to a corresponding display device or a display, as indicated in Figure 1.
  • the detector concept described below can also be used in connection with alterations ⁇ reindeer, not shown imaging systems.
  • a ring tunnel such as a Computertomogra ⁇ tomography system (CT).
  • CT Computertomogra ⁇ tomography system
  • Such a system may comprise a circular ring or circular-cylindrical detector and a rotatable X-ray source.
  • Ringtun ⁇ nel Positron Emission Tomography Systems (PET) and Single Photon Emission Computed Tomography Systems (SPECT), where the patient to be examined is injected with a radiopharmaceutical that is either direct (SPECT) or indirect (PET) generating emission of positrons gamma quanta. These can also be detected with a circular ring or circular-cylindrical detector.
  • Figure 2 shows a schematic perspective view of an insertable for detecting radiation quanta detector element 101, which is manufactured in a simple, cost-Wei ⁇ se and with compact dimensions
  • a radiation detector of an imaging system for example The detector 100 of the system 110 of FIG.
  • the detector element 101 has a superimposition of a scintillator 120, a photocathode 130, a microchannel plate 140 with a multiplicity of pixel-like microchannels (cf., the channels 145 indicated in FIG. 3), and a detection device 160.
  • the scintillator 120 serves to convert a high-energy radiation to be detected into a low-energy (re) radiation, which in turn is converted into electrons in the photocathode 130.
  • the Elect ⁇ Ronen generated from the photocathode 130 are multiplied in a rapid manner in the micro-channel plate 140, and using the detecting means 160 or with the aid of one or more provided here and serving as anodes (readout) electrodes ( "readout ubend") up This mode of operation will be discussed in more detail below in connection with FIG.
  • the detector element 101 and its individual components can each have (essentially) rectangular or cuboidal shapes.
  • the components of the detector element can have matching lateral dimensions 101 (in Wesentli ⁇ chen).
  • Anstel ⁇ le reckteckförmigen the external dimensions and square form (s) are also possible deviating geometries.
  • the components shown in Figure 2, but also in the other figures and their dimensions can not be true to scale darge ⁇ represents.
  • the scintillator 120 has a deviating significantly GroE ßere height of Figure 2, which exceeds the particular lateral dimen ⁇ solutions in order to obtain a high absorption of a to be detected in power incident radiation.
  • lateral dimensions in the range of several (for example 3 ⁇ 3) mm may be provided for the detector element 101.
  • the array of detector 160, microchannel plate 140, and photocathode 130 may be, for example a height in the range of 1 mm, and the scintillator 120 have a height in the range of 20 to 25 mm.
  • the detector element 101 or its scintillator 120 preferably faces the radiation to be detected, so that the radiation can enter or be coupled into the scintillator 120 via a front side of the scintillator 120 (upward-directed side in FIG. 3).
  • a high-energy incidence radiation quantum 200 (in particular X-ray quantum or gamma quantum) of the radiation to be detected can locally excite the scintillator 120.
  • the excitation energy deposited or during this operation absorbed are of acting as "Primae ⁇ res interaction material" scintillator 120 in the form of lower energy radiation quanta or photons 202 again.
  • the number of emitted photons 202 may be proportional to the original energy of the interacting with the scintillator material be radiation quants 200th on the case held Szintillationsmecha- mechanism will not be discussed.
  • the Szintil ⁇ lator 120 scintillation radiation it may be visible or ultraviolet light in particular.
  • the scintillation photons 202 (or a part thereof, which emerge on a rear side of the scintillator 120 opposite the front side) emitted by the scintillator 120 can interact with the photocathode 130, thereby generating free electrons 204.
  • the basis for this is the photoelectric effect.
  • the photocathode 130 can emit a photoelectron 204 for each incident or absorbed photon 202.
  • the electrons 204 generated with the aid of the photocathode 130 can be multiplied avalanche-like in the microchannel plate 145.
  • the microchannel plate 145 has a plate-shaped main body which is of a plurality (for example, a few thousand) microscopically fine channels
  • the channels 145 which may have lateral Abmessun ⁇ gen or a diameter in the range of, for example, 10 ym (or even smaller) may be arranged like pixels to each other in a close distance grid, and be formed mutually parallel running.
  • Zvi ⁇ rule including the channels 145 extend between the front and back of the micro-channel plate 145, applying an electrical voltage (accelerating voltage), whereby an electric field along the channels 145 is present.
  • a 130 emitted from the photocathode and to the front ⁇ side of the microchannel plate 140 in a channel 145 enter ⁇ the electron 204 is due to the see electric field in the direction of the rear side of the microchannel plate 140 and thus in the direction of the detection means 160 and the electrode (s) provided here moves or accelerates.
  • the small lateral dimensions of the channels 145 in this case cause that the electron 204 can encounter the wall of the channel 145 multiple times during this movement.
  • the primary electron 204 may extrude or knock out further electrons 204 (secondary electrons) from the channel wall.
  • the secondary electrons 204 can also accelerate within the channel 145 and release further (secondary) electrons 204 by collisions with the channel wall.
  • the 204 (hereinafter also referred to as “electron shower” or “electron cloud”) according to this process in the channels 145 of the microchannel plate 140 ⁇ multiplied electrons meet after emerging from the microchannel plate 140 at the rear thereof to the detection device 160 and the intended here (n) electrode (s), and are therefore recognized by the Erfas ⁇ sungs worn 160th In this case, a corresponding electrical output signal (for example voltage drop across a resistor) can be generated, which is dependent on the number or total charge of the electrons 204 collected in the detection device 160.
  • a relatively linear detection behavior may be present.
  • the detection means 160 Errei ⁇ sponding total charge, and thus a thereto based From ⁇ output signal substantially proportional to the energy of the interacting with the scintillator 120 radiation quantum 200.
  • the microchannel plate 140 and the grid or pixel-like structure favors.
  • the individual channels 145 each in Wesentli can ⁇ chen the same reinforcing or Elektronenvervielfa ⁇ deviation factor have so that there is a linear relationship between the number of interacting with the photocathode 130 scintillation 202 and the total charge detected by the detecting means 160th
  • the linear behavior of the detector element 101 made possible by means of the microchannel plate 140 also promotes the achievement of a high energy resolution.
  • microchannel plate 140 further leads to the fact that the detector element 101 by a small
  • the microchannel plate 140 may comprise, for example egg ⁇ ne dark rate below 1 counting event / cm 2 / s.
  • the microchannel plate 140 can also be formed with relatively small spacings between the individual channels 145, and consequently with a high porosity. For example, a porosity value in the range of 90% or more may be considered. Associated with this is a correspondingly high filling factor, which can reach almost 100%, and thus a high efficiency in the multiplication of the electrons 204 generated by means of the photocathode 130.
  • the filling factor of the microchannel plate 140 can far exceed that of a conventional silicon photomultiplier.
  • beschrie ⁇ surrounded detector element 101 may be made of the semiconductor and De- Tektortechnik known materials are used.
  • a entspre ⁇ sponding embodiment depends on the fact that on the one hand the voltage Toggle lying in use between the front and back of the microchannel plate 140 leads to no current flow between these two sides.
  • an activated channel 145 to charge preferably in a minimum amount of time to take place.
  • the micro-channel plate 140 may be formed, for example in the form of a provided with the micro-channels 145/2 semiconductor substrate, in particular silicon substrate, which is optionally substituted with a (weak) doping shipping ⁇ hen.
  • the present case conductivity provides the possibility of recharging the channels 145 may be in a period of time in nanoseconds den Kunststoff after ei ⁇ ner electron multiplication.
  • a relatively simple production of the microchannel plate 140 with the properties described above pixel-like arrangement of channels 145, high porosity
  • lithographic patterning and etching techniques can be used.
  • the microchannel plate 140 may further be configured such that the microchannel plate 140 additionally comprises further materials or layers in addition to a base or starting material, in particular a semiconductor material such as silicon. In particular it can be provided to form a thin coating with high secondary electron emission within the Ka ⁇ ducts 145 or to the channel walls in order to favor the electrical nenvervielfachung by wall collisions (not shown). Such a coating can be formed, for example, egg ⁇ nem metallic material. It is also possible that the microchannel plate 140 in the region of the channels 145 in ⁇ example additionally comprises an insulating layer such as an oxide layer, on which a layer with high secondary electron emission is arranged (not shown).
  • the micro-channel plate 140 may optionally be ⁇ additionally be provided on the front and / or rear side with a conductive or metallic layer via which electrical potentials and thus see an acceleration voltage may be applied to the microchannel plate 140th On the front ⁇ side, this can be done by a direct arrangement of the photocathode 130 on the microchannel plate 140.
  • the electrode (s) of the detection device 160 serving as anode (s) adjoin or are connected to the microchannel plate 140.
  • silicon silicon as the (base) material for the microchannel plate 140 also turns out its relatively high melting temperature (about 1420 ° C) as favorable.
  • materials can be used which can be formed on the microchannel plate 140 with the aid of high-temperature techniques or with the aid of deposition or coating processes carried out at high temperatures.
  • materials can be used which can be formed on the microchannel plate 140 with the aid of high-temperature techniques or with the aid of deposition or coating processes carried out at high temperatures.
  • This is particularly true for the above-indicated, possible case of the direct arrangement of the photocathode 130 in the form of a layer on the microchannel plate 140, which will be described below in connection with the embodiment shown in Figure 6 (photocathode 131 on microchannel plate 142).
  • the use of silicon for the microchannel plate 140 here makes it possible for the photocathode 130 to have a large number of different materials (and optionally formed with the aid of high-temperature or coating techniques).
  • Possible photocathode materials are, for example, Csl, CsTe, Cs3Sb, diamond and GaN.
  • the scintillator 120 the use of an inorganic material or a crystal is contemplated. Vorzugswei ⁇ se is, this is a "fast" scintillator 120, wherein the scintillation mechanism, ie, the imple- mentation of the incident high energy radiation in scintillation radiation takes place in a small period of time.
  • a thereof coming into consideration material is, for example, CsF or LSO.
  • the scintillator 120 and the photocathode 130 and the Ma ⁇ terialien are matched such that the light coming from the scintillator 120 scintillating radiation can be implemented in the photocathode 130 in free electrons.
  • the high diversity described above has denmaterialien usable Photokatho- to As a consequence, a number of different scintillator materials are also available for the scintillator 120. In this case, depending on the particular scintillator material selected (or on the wavelength or the wavelength range of the scintillation radiation produced in each case), a photocathode material adapted thereto ial be provided.
  • the detection device 160 may, for example, be designed like the microchannel plate 140 in the form of a semiconductor or silicon substrate. In this way, 160 is a well-known from the semiconductor technology bonding process can be carried out for connecting these two components 140, as further below in more detail be ⁇ written with reference to the embodiments of Figures 8 to. 11
  • the detection means 160 may, for example, a single or large ⁇ area electrode having (not shown) which the microchannel plate 140 is provided for collecting electrons showers of all the channels 145th
  • the schematic AufSichtsdar ein the detector element 101 of Figure 4 shows an alternative embodiment.
  • the detection device 160 has a plurality of electrodes 161, wherein the electrodes 161, as indicated in Figure 4 on the basis of a single line, pixel-like or matrix-like in the form of rows and columns can be arranged side by side.
  • Each electrode 161 may in this case be provided for collecting electrons of a plurality of channels 145, as illustrated in FIG. 4 with reference to the electrode 161 assigned to the left and assigned to four channels 145. Notwithstanding FIG. 4, a single electrode 161 can also be assigned to a different number of channels 145, or else only one channel 145.
  • the provision of a plurality of electrodes 161 in the detection device 160 of the detector element 101 makes it possible to detect not only the energy of a radiation quantum 200 interacting with the scintillator 120, but also the (lateral) location of the interaction in the scintillator 120. With the aid of the plurality of electrodes 161, the charge center of the electron cloud coming from the microchannel plate 140 can be determined, which can be dependent on the location of interaction of the radiation quantum 200 in the scintillator 120.
  • the detector element 101 and thus also a detector with a plurality of detector elements 101 of an imaging system constructed in this way can optionally have a relatively high spatial resolution in this way.
  • a further possible variant is an embodiment of the detection device 160 in the form of an application-specific integrated circuit (ASIC) .
  • ASIC application-specific integrated circuit
  • an embodiment of the detection device 160 in the form of a semiconductor substrate or ASIC circuit offers the possibility of the detection device 160 together with the microchannel plate 140 (and optionally the Pho ⁇ tokathode 130 in an arrangement thereof on the Mikroka ⁇ nalplatte 140) on "wafer level "to connect to an integrated component or a" monolithic package ".
  • a component can be made particularly compact and are characterized by minimal interfaces between the individual components.
  • FIG. 5 shows a schematic side view of a detector element 101, which has substantially the same construction as the detector element shown in Figure 3 at 101 ⁇ .
  • a microchannel plate 141 preferably again comprising a semiconductor material such as silicon
  • pre ⁇ see whose channels 145 obliquely tilted with respect to a standardization times a through the micro-channel plate 141 (or by its front and / or rear) predetermined level are arranged.
  • an angle in a range of 10 ° between the plate normal and a longitudinal axis of the Ka ⁇ channels 145 may be provided.
  • the tilted configuration of the channels 145 of the microchannel plate 141 with the result that the coming from the photocathode 130 electrons 204 reliably and, in particular inde ⁇ pending repeatedly discharged from the entrance angle when entering the channels 145 at the channel walls and release consequently further electrons 204 , where the electrons 204 can be detected again by a detection device 160 with (preferably) a plurality of electrodes 161.
  • a "fall through" of a primary electron 204 through a channel 145 without wall contact and thus without electron multiplication can thus be avoided, with a high reliability and homogeneity of the electron multiplication being associated with such a tilted configuration of microchannels can also be provided for the embodiments described below be.
  • Figure 6 shows a schematic side view of another detector element 101 with a microchannel plate 142, which preferably comprises a semiconductor material such as in particular silicon.
  • a microchannel plate 142 which preferably comprises a semiconductor material such as in particular silicon.
  • the formed in the form of a continuous layer of ⁇ photocathode 131 has openings 135, over wel ⁇ che channels 145 of the microchannel plate 142 are exposed. As indicated above, a corresponding electrical potential can be applied to the front of the microchannel plate 142 via the photocathode 131.
  • the photocathode 131 is a so-called reflection Photo ⁇ cathode 131, which emits photoelectrons from the same side on which also impinges the light coming from the scintillator 120 radiation.
  • the 131 emit ⁇ benefited from the photocathode electrons through the openings 135 of the photocatalytic Method 131 in the channels 145 of the microchannel plate 142 gelan ⁇ conditions, and as described above in the channels 145 multiplied and subsequently detected by a detection device 160.
  • the photocathode 131 may be formed solid and with a relatively large thickness. This leads to a high degree of reliability and efficiency in the Pho realized by means of the ⁇ tokathode 131 implementation of the gate of the scintillator 120 emitted radiation into photoelectrons.
  • the micro-channel plate 142 has ⁇ at the scintillator 120 opposite side a structured surface with elevations 147 between the channels 145.
  • the elevations 147 have a shape or contour decreasing in the direction of the scintillator 120, and are embodied, for example, as trapezoidal or tetrahedral.
  • the reflective working photocathode 131 is angeord ⁇ net.
  • the photocathode 131 in this case has a correspondingly structured or profiled (surface) form, and thus an enlarged surface. In this way, an efficient conversion of the scintillation radiation impinging on the photocathode 131 into electrons can be further promoted.
  • FIG. 7 shows a schematic side view of a further detector element 101, which has a microchannel plate 143 with an additional electrode 153 arranged within the microchannel plate 143.
  • the electrode 153 acting as a dynode offers the possibility of also causing a release of electrons when an impact of electrons occurs.
  • the electrode 153 comprises a material having a high secondary electron emission, for example a metallic material.
  • the microchannel plate 143 is constructed of two stacked sub-plates 150, 151.
  • the partial plates 150, 151 may each be in the form of a semiconductor or silicon substrate, and have mutually aligned channels 155, 158.
  • Both partial plates 150, 151 can be connected to one another by a bonding method known from semiconductor technology.
  • the lower part of plate 150 has a structured surface with elevations 156 between the channels 155 at the adjacent to the top Crystalplat ⁇ te 151 side or front.
  • the elevations 156 have a narrowing in the direction of the upper part plate 151 form, for example, a trapezoidal or tetrahedral shape.
  • On this side of the sub-panel 150 that is, on the projections 156 and on inclined Abschnit ⁇ th in an edge region of the sub-plate 150, and the present in the form of a continuous layer electrode 153 is formed, which is therefore a correspondingly structured or profiled (surface ) Owns form.
  • the electrode 153 also has openings 154, over which the channels 155 of the lower part plate 150 are exposed, so that
  • the upper partial plate 151 has, on a side or front side opposite a scintillator 120 (or its rear side), the structure described above in connection with FIG. 6 (structured surface with elevations 147, photo ⁇ cathode layer 131). Furthermore, the channels 158 of the upper partial plate 151 are in the direction of the rear side and thus in
  • the detector element 101 of Figure 7 is an electrical potential is applied (via an unillustrated on ⁇ circuit structure) to the electrode 153, the size between the sizes of nalplatte the front and back of the microchannel 143 is applied potentials. In this way, 151 located respectively multiplied electrons to the electrode 153 can be ⁇ be accelerated and impinge on this under knocking out further electrons in the channels 158 of the top plate.
  • the electrons can enter the channels 155 of the lower sub-plate 150, release further electrons here and continue to a detection device 160.
  • an additional electron multiplication can be caused in addition to the electron multiplication taking place on channel walls.
  • microchannel plates vorstell ⁇ bar which are also comprised of stacked sub-plates, but multiple (superposed) internal Include electrodes. It should also be pointed out that the provision of partial plates and one or more internal electrodes can also be considered in the embodiments described below.
  • a detector element 101 requires the existence of a vacuumed atmosphere or a vacuum (at least) in the region in which free electrons are present, ie in particular in the channels of a microchannel plate 140, 141, 142, 143 and on the front side
  • ⁇ term input and the rear output region of the respective microchannel plate 140, 141, 142, 143 or in the region of an associated photocathode 130, 131 and a detection device 160 For this purpose, it is possible to consider corresponding seals of the microchannel plate 140, 141, 142, 143 in the area of their front and back provide. This can be done at the front by means of an additional interconnecting element, and at the back via a detection device 160. An embodiment which is possible or preferred in this respect is explained in more detail below.
  • FIG. 8 shows a schematic side view of components of a further detector element 101
  • Figure 9 illustrates a side view of the assembled by Verbin ⁇ this component detector element 101
  • the detector element 101 includes a, preferably a semiconducting ⁇ termaterial such as in particular silicon-containing microchannel ⁇ plate 142 with the structure described with reference to FIG. 6, ie with a structured front with elevations and with a reflection photocathode layer 131 arranged on the front side.
  • an interconnecting member 170 is provided on the front side of the microchannel plate 142 and thus between the microchannel plate 142 and a scintillator 120 of the detector element 101.
  • intermediate connecting member 170 Serving as the entry window ⁇ intermediate connecting member 170 is istläs ⁇ for the sig of the scintillator 120 emitted (at the rear) radiation.
  • the scintillation radiation can thus reach the photocathode 131, as a result of which the photocathode 131 emits electrons as described above, which can be multiplied in the channels 145 of the microchannel plate 142 and detected by a detection device 160.
  • a glass material is considered for the plate-shaped interconnecting member 170.
  • the microchannel plate 142 On the peripheral rim of the microchannel plate 142, which via the provided with the photocathode 131 area the microchannel plate 142 protrudes, one hermetically tight connection with the intermediate connection element 170 ago ⁇ made.
  • a layer 185 out ⁇ forms in the edge region of the microchannel plate 142, which is adjacent to the photo-cathode layer 131 and is connected thereto.
  • a further bonding layer 182 is provided, via which the intermediate is ⁇ connecting member 170 is connected to the microchannel plate 142 and with its layer 185th.
  • the layers 182, 185 comprise electrically conductive or metallic materials, and are, for example, by performing a eutectic bonding process or a thermal compression bonding process with ⁇ connected to each other.
  • the layers 182, 185 may also be present in the form of a common layer or eutectic alloy. Instead of the use of two layers 182, 185, the use of only one of the micro-channel plate 142 to the intermediate connecting member 170 verbin ⁇ emissive layer is alternatively possible.
  • a hermetically sealed and peripheral connection is furthermore produced in an edge region on the rear side of the microchannel plate 142 to the detection device 160 of the detector element 101, as indicated by a further connection layer 181.
  • it can be a used in the context of the above bonding processes or out ⁇ formed layer may optionally be composed of several layers or materials.
  • the particular conducted connection process is the production of at least one compound, ie 160, carried out in an evacuated environment on the one hand between the microchannel plate 142 and interconnect member 170 and on the other hand between the microchannel plate 142 and Erfas ⁇ sungs liked, thus set in the area of the microchannel plate 142, a corresponding vacuum can.
  • a connection 187 may be formed on the intermediate connection element 170, in particular on its side. This is about the routing ⁇ capable layers 182, 185 further electrically connected to the photocatalytic Thode 131 is connected. Via the connection 187, an electrical potential, in particular a high-voltage potential, can be applied to the photocathode 131 and thus to the front side of the microchannel plate 142.
  • An adapted Ge ⁇ genpotential can for example be applied via the detection device 160 and the connection layer 181 to the back of the microchannel plate 142 and to a here provided (not shown) conductive layer.
  • FIG. 9 also indicates that the detection device 160, which is preferably designed in the form of an application-specific integrated circuit with, in particular, a plurality of electrodes 161, can have via holes 165 ("through silicon via", TSV). Signals are transmitted to corresponding pads or pads (not shown) at the bottom of detector 160.
  • Figure 9 further shows a printed circuit board 190 connected to detector 160 or its bottom pads is connected via solder balls 192.
  • a plurality of detector elements 101 may be arranged side by side on a common printed circuit board 190.
  • FIG. 10 shows a schematic side view of components of a further detector element 101
  • FIG. 11 illustrates a side view of the detector element 101 constructed by connecting these components. This has a structure comparable to the embodiment of FIGS. 8, 9, see FIG that reference is made to the foregoing with respect to details of consistent components and aspects.
  • the detector element 101 of Figure 11 includes a vorzugswei ⁇ se formed of a semiconductor material such as silicon, and in particular provided with channels 145 microchannel plate 144, which is connected on the back via a connection layer 181 with a detection means 160th At the front of the microchannel plate 144 is connected via a Verbin ⁇ -making layer 182 a serving as the entrance window of the interconnect member 170 is disposed on which further comprises a scintillator 120th
  • layered photocathode 132 is arranged ⁇ .
  • the radiation coming from the scintillator 120 can in this case penetrate the interconnecting element 170 and impinge on the photocathode 132.
  • the emittier- th from the photocathode 132 electrons multiplied in the channels 145 of the microchannel plate 144 again, and are detected by the Er chargedseinrich ⁇ tung 160th
  • the interconnection element 170 is also provided in this embodiment with a terminal 187, which electrically via the connection layer 182 with the photocathode 132 and with the front of the microchannel plate 144 (or a here optionally provided conductive coating) is connected. Since the photocathode 132 is not arranged on the front ⁇ side of the microchannel plate 144, the Mik ⁇ rokanalplatte 144 at this point also no surveys between see the channels 145 on.
  • a glass material may occur (as a base material) for a Mikrokanalplat ⁇ te into consideration, for example, instead of a semiconductor material, or instead of silicon.
  • one possible modification of the microchannel plate 142 shown here is to provide no structured front or elevations 147.
  • the photocathode 131 disposed on the microchannel plate 142 may be in the form of a planar layer.
  • FIGS. 10 and 11 have an internal electrode and are constructed of a plurality of stacked sub-plates.
  • a detection device 160 can only be designed to detect an electron cloud by means of one or more electrodes and optionally amplify corresponding output signals.
  • processing and evaluation of output signals elsewhere can be done by another device.
  • a detector of an imaging system constructed of a plurality of detector elements 101 for example the detector 100 of the system of FIG. 1, may comprise such a device.
  • Processing can also be effected only by a central evaluation device, with regard to FIG. 1, for example, by the control and evaluation device 114.
  • a detection device 160 may comprise other electrode arrangements, for example in the form of crossed strip conductors or strip-shaped electrodes. Also, a detector 160 may not only be in the form of a semiconductor substrate, but alternatively also for example in the form of one with one or more
  • Electrode provided ceramic carrier may be formed.
  • providing a vacuum in the region of a microchannel plate may be accomplished other than by providing seals to the microchannel plate as described with reference to FIGS. 8 to 11.
  • one or more detector elements may (at least partially) be arranged in a suitable, evacuated housing.
  • Another possible modification consists in a Ausgestal ⁇ tung a single detector element having a plurality of adjacent scintillators or Szintillatorkristal- len.
  • the plurality of scintillators can here be arranged on a common microchannel plate. Between the scintillators and the microchannel plate, one or more juxtaposed photocathode and be appropriate, one or more side by side arranged and serving as the entrance window between connecting elements pre see ⁇ gegebe ⁇ . Also, below the microchannel plate has a ge ⁇ my same detection device with a plurality of different scintillators associated electrodes may be provided.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)
  • Nuclear Medicine (AREA)
  • Electron Tubes For Measurement (AREA)

Abstract

L'invention concerne un détecteur de rayonnement (100; 101) comprenant un scintillateur (120) servant à générer un rayonnement électromagnétique (202) sous l'effet d'un rayonnement incident (200), une photocathode (130; 131; 132) servant à générer des électrons (204) sous l'effet du rayonnement électromagnétique (202) généré par le scintillateur (120), une plaquette à microcanaux (140; 141; 142; 143; 144) comprenant une pluralité de canaux (145; 155; 158) pour multiplier les électrons (204) générés par la photocathode (130; 131; 132), et un dispositif de détection (160) servant à détecter les électrons (204) multipliés à l'aide de la plaquette à microcanaux (140; 141; 142; 143; 144). L'invention concerne également un système d'imagerie (110) comprenant un tel détecteur de rayonnement (100; 101).
PCT/EP2012/060564 2011-06-07 2012-06-05 Détecteur de rayonnement et système d'imagerie Ceased WO2012168218A2 (fr)

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DE102011077058A DE102011077058A1 (de) 2011-06-07 2011-06-07 Strahlungsdetektor und bildgebendes System
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Publication number Priority date Publication date Assignee Title
WO2021055663A1 (fr) * 2019-09-20 2021-03-25 Waymo Llc Réseau de photomultiplicateurs au silicium monolithiques
US11145778B2 (en) 2019-09-20 2021-10-12 Waymo Llc Monolithic silicon photomultiplier array
JP2022548093A (ja) * 2019-09-20 2022-11-16 ウェイモ エルエルシー モノリシックシリコン光電子増倍管アレイ
JP7420927B2 (ja) 2019-09-20 2024-01-23 ウェイモ エルエルシー モノリシックシリコン光電子増倍管アレイ
US12155000B2 (en) 2019-09-20 2024-11-26 Waymo Llc Monolithic silicon photomultiplier array
CN112857441A (zh) * 2021-01-08 2021-05-28 北京艾旗斯德科技有限公司 一种集生物检测、医疗诊断的安检通道系统
CN116190192A (zh) * 2023-03-30 2023-05-30 北方夜视技术股份有限公司 高增益快响应微通道板及其制备方法

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