CA2228117A1 - Flat panel detector for radiation imaging and pixel for use therein - Google Patents
Flat panel detector for radiation imaging and pixel for use therein Download PDFInfo
- Publication number
- CA2228117A1 CA2228117A1 CA002228117A CA2228117A CA2228117A1 CA 2228117 A1 CA2228117 A1 CA 2228117A1 CA 002228117 A CA002228117 A CA 002228117A CA 2228117 A CA2228117 A CA 2228117A CA 2228117 A1 CA2228117 A1 CA 2228117A1
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- radiation
- pixel
- charge
- pixel electrode
- 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.)
- Abandoned
Links
- 230000005855 radiation Effects 0.000 title claims abstract description 93
- 238000003384 imaging method Methods 0.000 title claims abstract description 21
- 239000003990 capacitor Substances 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims description 23
- 239000004065 semiconductor Substances 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 8
- 239000010409 thin film Substances 0.000 claims description 5
- 239000011669 selenium Substances 0.000 description 9
- 229910052711 selenium Inorganic materials 0.000 description 7
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 6
- 239000010408 film Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- AQCDIIAORKRFCD-UHFFFAOYSA-N cadmium selenide Chemical compound [Cd]=[Se] AQCDIIAORKRFCD-UHFFFAOYSA-N 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000000190 proton-induced X-ray emission spectroscopy Methods 0.000 description 1
- 150000003342 selenium Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
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
- G01T1/24—Measuring radiation intensity with semiconductor 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
- G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
- G01T1/2914—Measurement of spatial distribution of radiation
- G01T1/2921—Static instruments for imaging the distribution of radioactivity in one or two dimensions; Radio-isotope cameras
- G01T1/2928—Static instruments for imaging the distribution of radioactivity in one or two dimensions; Radio-isotope cameras using solid state detectors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
- H01L27/14658—X-ray, gamma-ray or corpuscular radiation imagers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14665—Imagers using a photoconductor layer
- H01L27/14676—X-ray, gamma-ray or corpuscular radiation imagers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/30—Transforming light or analogous information into electric information
- H04N5/32—Transforming X-rays
Abstract
A flat panel detector (20) for radiation imaging includes an array of pixels (22) arranged in rows and columns. Gate lines (24) interconnect the pixels of each row while source lines (26) interconnect the pixels of each column. A
radiation transducer (CSE) is disposed over the array. Each pixel includes a TFT switch (38) having its gate electrode connected to a gate line (24) and its source electrode (42) connected to another gate line. The drain electrode (40) of TFT switch (38) constitutes the pixel electrode of pixel (22). The drain electrode and a bottom electrode (52) connected to source line (26) constitute a storage capacitor (CST). When TFT switch is biased and the drain electrode is charged, the drain electrode discharges through TFT switch on to the source terminal and to the gate line. This results in a release of the charge held by the bottom electrode which is sensed by a charge amplifier connected to the source line.
radiation transducer (CSE) is disposed over the array. Each pixel includes a TFT switch (38) having its gate electrode connected to a gate line (24) and its source electrode (42) connected to another gate line. The drain electrode (40) of TFT switch (38) constitutes the pixel electrode of pixel (22). The drain electrode and a bottom electrode (52) connected to source line (26) constitute a storage capacitor (CST). When TFT switch is biased and the drain electrode is charged, the drain electrode discharges through TFT switch on to the source terminal and to the gate line. This results in a release of the charge held by the bottom electrode which is sensed by a charge amplifier connected to the source line.
Description
CA 02228ll7 l998-0l-28 F~AT P}~NE~ D~ ~OK FOR RL~DIATION IkC~GING ~ND
PIXE~ FOR USE THERETN
TECHnNICAL FIELD
The present invention relates to imaging systems and in particular to a flat panel detector for radiation imaging and to a pixel for use in a flat panel detector.
BA~KGR~YND ART
Flat panel detectors for use in x-ray radiation imaging systems are known. Examples of these pixel sensor arrays can be found in U.S. Patent Nos. 5,184,018 and 5,381,014. One such type of flat panel detector includes a thick amorphous selenium film (a-Se) on a two-dimensional TFT switch array. The TFT switches are arranged in rows and columns to form a two-dimensional imaging system. Gate lines interconnect the TFT switches in each row while source lines interconnect the TFT
switches in each column. The thick selenium film is deposited directly on top of the TFT switch array and a top electrode is deposited on the selenium film.
When x-rays are incident on the selenium film and the top electrode is biased with a high voltage, electron-hole pairs are separated by the electric field across the thickness of the selenium film. The holes which are driven by the electric field move toward the pixel electrodes (i.e. the drain electrodes of the TFT
switches) and accumulate. This results in a charge being held by the pixel electrodes which can be used to develop an x-ray image. The charge held by the pixel electrodes can be read by supplying a pulse to each gate line. When a gate line receives a pulse, the TFT switches in the row turn on, allowing the signal charges on the pixel electrodes to discharge through the TFT switches on to the source lines. Charge amplifiers connected to the source lines sense the charge and provide output voltage signals proportional to the charge and hence, proportional to the radiation exposure on the selenium film. t Although this pixel design is satisfactory, alternative designs are continually being sought. It is therefore an object of the present invention to provide a novel flat panel detector for radiation imaging and a pixel for use therein.
DI8CLOSURE OF THE lNV~:L.~ lON
According to one aspect of the present invention there is provided a pixel for a radiation imaging flat panel detector comprising:
a radiation transducer to be exposed to incident radiation;
a pixel electrode on one side of said radiation transducer to accumulate a positive charge proportional to the exposure of said radiation transducer to radiation;
a second electrode separated from said pixel electrode by a dielectric and connected to a source line, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
WO 97/056~8 PCT/CA95/00456 According to another aspect of the present invention there is provided a flat panel detector for radiation imaging comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
According to yet another aspect of the present invention there is provided a flat panel detector for radiation imaging comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer and formed on a common substrate;
a plurality of sources lines formed on said substrate and upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines formed on said substrate and upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including: a thin film transistor switch having a drain electrode constituting a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a bottom electrode separated from said pixel electrode by a dielectric gate insulating layer and connected to one of said source lines, said pixel and bottom electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a source electrode coupled to a low potential terminal, said thin film transistor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
.
According to still yet another aspect of the present invention there is provided a radiation imaging system including a radiation source and a flat panel detector, said flat panel detector comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows anol columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array;
a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array;
an array of charge amplifiers, each connected to one of said source lines to detect the charge thereon;
and a gate driver to supply gating signal to said gate lines in succession to allow the charges accumulated by said pixels to be detected on a row-by-row basis, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel r electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected by said charge amplifier.
The present invention provides a relatively simple circuit design with m;n;~l hardware components for detecting the exposure of a radiation transducer to radiation avoiding the need to discharge a capacitive transducer through a transistor to a charge amplifier.
In addition, when two source lines are used with each pixel, the effects of noise on the source lines are significantly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described more fully with reference to the accompanying drawings in which:
Figure 1 is a schematic of a flat panel detector for radiation imaging in accordance with the present invention;
Figure 2 is an equivalent circuit of a pixel forming part of the flat panel detector of Figure 1;
Figure 3 is a top plan view of a pixel forming part of the flat panel detector of Figure 1;
Figure 4 is a cross-sectional view of the pixel of Figure 3 taken along line 4-4;
Figure 5 is an e~uivalent circuit of an alternative embodiment of a pixel for a flat panel detector for radiation imaging; and CA 02228ll7 l998-0l-28 W O 97/05658 PCT/CA9~/00156 Figure 6 is a schematic of a radiation imaging ~ystem incorporating a flat panel detector.
BE8T NODES FOR CARRYING OU~ THB lwv~wllON
Referring now to Figure 1, a flat panel detector for radiation imaging is shown and is generally indicated by reference numeral 20. The flat panel detector includes a plurality of pixels 22 arran~ed in rows and columns. Gate lines 24 formed of Chromium interconnect the pixels 22 of each row while source lines 26 interconnect the pixels 22 of each column. The gate lines 24 lead to a gate driver circuit 28 which provides pulses to the gate lines in succession in response to input from a control circuit 29. The source lines 26 lead to charge amplifiers 30 which in turn are connected to an analog multiplexer 32. The analog multiplexer provides image output which can be digitized to create a digitized radiation image in response to input from the control circuit 29.
Figure 2 shows an equivalent circuit of one of the pixels 22. As can be seen, the pixel includes a radiation transducer C~ coupled to node C and to a high potential voltage source 74 in the order of 3kV. A
storage capacitor C~ is also coupled to node C as well as to source line 26. The drain electrode 40 of a thin film transistor ("TFT") switch 38 is also coupled to node C
and defines the pixel electrode of pixel 22. The source electrode 42 of TFT switch 38 is coupled to one of the gate lines 24 while the gate electrode of the TFT switch 38 is coupled to another of the gate lines 24.
Referring now to Figures 3 and 4, one of the pixels 22 formed in accordance with the present invention is better illustrated. A bottom electrode 52 is formed on a glass substrate 50 together with the source line 26 8 _ and is electrically connected to the source line 26. A
dielectric layer 53 overlies the source line 26, bottom electrode 52 and substrate 50. The gate line 24 is deposited on dielectric layer 53 and is ~ormed of Chromium.
s A gate insulating layer 54 formed of SiO2 or SiN~ overlies the gate line 24 and dielectric layer 53. Deposited on the gate insulating layer 54 above the gate line 24 is a semiconductor material layer formed of Cadmium Selenide (CdSe) defining the channel 56 of the T~T switch 38.
Contacting the channel 56 are the drain and source electrodes 40 and 42 respectively of the TFT switch 38. A
passivation layer 58 formed of sio2 or Si covers the portion of the channel 56 not covered by the drain and source electrodes.
Above the TFT switch array is the radiation transducer Cs~. The radiation transducer is in the form of a selenium (Se) radiation conversion layer 70 having a thickness of approximately 300~m to 500~m. Above the radiation conversion layer is a top electrode 72 formed of In, Al or Au. The top electrode 72 is coupled to a high potential voltage source 74 to provide the necessary bias to the radiation transducer CSE. The top electrode 72 and the drain electrode 40 form the electrodes of radiation transducer CSE while the drain electrode 40 and bottom electrode 52 form the electrodes of storage capacitor CST.
Although only one pixel 22 is shown, it should be realized that each of the pixels 22 in the array are identical and that the pixels are formed on the substrate 50 simultaneously by depositing appropriate layers on the substrate and etching them as required.
In operation, the top electrode 72 is biased to a high potential by voltage source 74 and the flat panel detector 20 is exposed to radiation, resulting in an AME~1DEOS~EFT
electric field being created in the radiation conversion layer 70 which causes electrons to move towards the top electrode 72 and holes to move towards the drain or pixel electrodes 40. The majority of the holes drift to the drain electrodes where positive charges are accumulated.
While the flat panel detector 20 is being exposed to radiation, the gate lines 24 are suitably maintained to keep the TFT switches 38 in an off-state.
With the TFT switches off, as the drain electrodes 40 accumulate positive charges, negative charges are pulled on to the bottom electrodes 52 from the charge amplifiers 30 via the source lines 26 so that equal and opposite charges appear at the electrodes 40 and 52 constituting the storage capacitors C~.
After the flat panel detector 20 has been exposed to radiation and it is desired to create an image, a bias is applied to each gate line 24 in succession by the gate driver 28 in response to input from the control circuit 29. When a bias is applied to a gate line 24, all of the TFT switches 38 connected to that gate line turn on. This allows the charges held by the bottom electrodes 52 of those pixels to be sensed by the charge amplifiers 30 connected to the source lines 26 ext~n~;ng to those pixels 22. Thus, by biasing the gate lines 24 in succession, a radiation image can be created on a row-by-row basis. The manner in which the charge held by bottom electrodes 52 is sensed will now be described with reference to a single pixel 22.
When the bias is applied to the gate line 24, the TFT switch 38 is conditioned to an on-state. With the TFT switch on, the drain electrode 40 is electrically coupled to the source electrode 42 and hence, to the gate line 24 associated with another row of pixels 22 through the TFT switch 38. At this stage, the other gate line 24 is grounded and therefore, is at a low potential.
When this occurs, the charge held by the drain electrode 40 is discharged through the TFT switch 38 on to the gate line 24 at ground. As this occurs, the negative charge on the bottom electrode 52 pulled from the charge amplifier 30 via source line 26 is released.
This change in charge on the source line 26 is sensed by the charge amplifier 30. Since the charge on the bottom electrode 52 is proportional to the exposure of the radiation transducer CSE to radiation, the change in charge sensed by the charge amplifier 30 is also proportional to the exposure of the radiation transducer to radiation. The charge amplifier 30 in turn generates output representative of the exposure of the radiation transducer CSE to radiation and conveys the output to the analog multiplexer 32.
Referring now to Figure 5, another embodiment of a pixel for use in a flat panel detector for radiation imaging is shown and is generally indicated by reference numeral 122. The pixel 122 is very similar to that shown in the previous embodiment with the exception that the source electrode 142 of TFT switch 138 is connected to a second source line 126', rather than to the gate line 124. In this embodiment, the source lines 126 and 126' associated with the pixel 122 lead to a balanced charge amplifier 130. Because each pixel has two source lines, noise contributed by one source line 126 cancels the noise contributed by the other source line 126' reducing the overall effect of noise. Also, the use of two source lines helps to reduce the contribution of even harmonics generated by the TFT switch 138 as well as to reduce the effects of odd harmonics.
During operation of the pixel 122, after the flat panel detector has been exposed to radiation and the bottom electrode is charged, when the bias is applied to the gate line 124, the charge held by the drain electrode 140 is discharged through TFT switch 138 on to source line 126' where it is sensed by charge amplifier 130. At the same time, the charge on the bottom electrode 5Z is released. The resulting change in charge on the source line 126 is also sensed by the charge amplifier 130. The balanced charge amplifier 130 detects the input from the source lines 126 and 126' and generates an output voltage proportional to the exposure of the pixel 122 to radiation.
Figure 6 shows an x-ray imaging system 200 for tAki~g a radiation image of an object 202. The x-ray imaging system 200 includes a radiation source 204 and a flat panel detector 206. The flat panel detector can include pixels of the type shown in Figures 2 or 5. As can be seen, when an x-ray image of an object is to be taken, the object 202 is placed between the radiation source 204 and the flat panel detector 206 and the object is exposed to x-ray radiation. X-ray radiation passing through the object 204 contacts the flat panel detector 206 allowing for an image of the object to be taken in the manner described previously.
As should be appreciated by those of skill in the art, the present invention allows charges accumulated by the pixel electrodes to be sensed without discharging the charge through TFT switches to the charge amplifiers.
Also, when two source lines are used in each pixel, electronic noise is reduced. Although reference has been made to specific materials forming the various components of the pixels, those of skill in the art will appreciate that other suitable materials can be used. Those of skill in the art will also appreciate that variations and modifications may be made to the present invention without departing from the scope thereof as defined by the appended claims.
PIXE~ FOR USE THERETN
TECHnNICAL FIELD
The present invention relates to imaging systems and in particular to a flat panel detector for radiation imaging and to a pixel for use in a flat panel detector.
BA~KGR~YND ART
Flat panel detectors for use in x-ray radiation imaging systems are known. Examples of these pixel sensor arrays can be found in U.S. Patent Nos. 5,184,018 and 5,381,014. One such type of flat panel detector includes a thick amorphous selenium film (a-Se) on a two-dimensional TFT switch array. The TFT switches are arranged in rows and columns to form a two-dimensional imaging system. Gate lines interconnect the TFT switches in each row while source lines interconnect the TFT
switches in each column. The thick selenium film is deposited directly on top of the TFT switch array and a top electrode is deposited on the selenium film.
When x-rays are incident on the selenium film and the top electrode is biased with a high voltage, electron-hole pairs are separated by the electric field across the thickness of the selenium film. The holes which are driven by the electric field move toward the pixel electrodes (i.e. the drain electrodes of the TFT
switches) and accumulate. This results in a charge being held by the pixel electrodes which can be used to develop an x-ray image. The charge held by the pixel electrodes can be read by supplying a pulse to each gate line. When a gate line receives a pulse, the TFT switches in the row turn on, allowing the signal charges on the pixel electrodes to discharge through the TFT switches on to the source lines. Charge amplifiers connected to the source lines sense the charge and provide output voltage signals proportional to the charge and hence, proportional to the radiation exposure on the selenium film. t Although this pixel design is satisfactory, alternative designs are continually being sought. It is therefore an object of the present invention to provide a novel flat panel detector for radiation imaging and a pixel for use therein.
DI8CLOSURE OF THE lNV~:L.~ lON
According to one aspect of the present invention there is provided a pixel for a radiation imaging flat panel detector comprising:
a radiation transducer to be exposed to incident radiation;
a pixel electrode on one side of said radiation transducer to accumulate a positive charge proportional to the exposure of said radiation transducer to radiation;
a second electrode separated from said pixel electrode by a dielectric and connected to a source line, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
WO 97/056~8 PCT/CA95/00456 According to another aspect of the present invention there is provided a flat panel detector for radiation imaging comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
According to yet another aspect of the present invention there is provided a flat panel detector for radiation imaging comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer and formed on a common substrate;
a plurality of sources lines formed on said substrate and upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines formed on said substrate and upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including: a thin film transistor switch having a drain electrode constituting a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a bottom electrode separated from said pixel electrode by a dielectric gate insulating layer and connected to one of said source lines, said pixel and bottom electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a source electrode coupled to a low potential terminal, said thin film transistor switch being responsive to a gating signal to connect electrically said pixel electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
.
According to still yet another aspect of the present invention there is provided a radiation imaging system including a radiation source and a flat panel detector, said flat panel detector comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows anol columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array;
a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array;
an array of charge amplifiers, each connected to one of said source lines to detect the charge thereon;
and a gate driver to supply gating signal to said gate lines in succession to allow the charges accumulated by said pixels to be detected on a row-by-row basis, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge approximately equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a low potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel r electrode to said low potential terminal to discharge said pixel electrode thereon, said bottom electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected by said charge amplifier.
The present invention provides a relatively simple circuit design with m;n;~l hardware components for detecting the exposure of a radiation transducer to radiation avoiding the need to discharge a capacitive transducer through a transistor to a charge amplifier.
In addition, when two source lines are used with each pixel, the effects of noise on the source lines are significantly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described more fully with reference to the accompanying drawings in which:
Figure 1 is a schematic of a flat panel detector for radiation imaging in accordance with the present invention;
Figure 2 is an equivalent circuit of a pixel forming part of the flat panel detector of Figure 1;
Figure 3 is a top plan view of a pixel forming part of the flat panel detector of Figure 1;
Figure 4 is a cross-sectional view of the pixel of Figure 3 taken along line 4-4;
Figure 5 is an e~uivalent circuit of an alternative embodiment of a pixel for a flat panel detector for radiation imaging; and CA 02228ll7 l998-0l-28 W O 97/05658 PCT/CA9~/00156 Figure 6 is a schematic of a radiation imaging ~ystem incorporating a flat panel detector.
BE8T NODES FOR CARRYING OU~ THB lwv~wllON
Referring now to Figure 1, a flat panel detector for radiation imaging is shown and is generally indicated by reference numeral 20. The flat panel detector includes a plurality of pixels 22 arran~ed in rows and columns. Gate lines 24 formed of Chromium interconnect the pixels 22 of each row while source lines 26 interconnect the pixels 22 of each column. The gate lines 24 lead to a gate driver circuit 28 which provides pulses to the gate lines in succession in response to input from a control circuit 29. The source lines 26 lead to charge amplifiers 30 which in turn are connected to an analog multiplexer 32. The analog multiplexer provides image output which can be digitized to create a digitized radiation image in response to input from the control circuit 29.
Figure 2 shows an equivalent circuit of one of the pixels 22. As can be seen, the pixel includes a radiation transducer C~ coupled to node C and to a high potential voltage source 74 in the order of 3kV. A
storage capacitor C~ is also coupled to node C as well as to source line 26. The drain electrode 40 of a thin film transistor ("TFT") switch 38 is also coupled to node C
and defines the pixel electrode of pixel 22. The source electrode 42 of TFT switch 38 is coupled to one of the gate lines 24 while the gate electrode of the TFT switch 38 is coupled to another of the gate lines 24.
Referring now to Figures 3 and 4, one of the pixels 22 formed in accordance with the present invention is better illustrated. A bottom electrode 52 is formed on a glass substrate 50 together with the source line 26 8 _ and is electrically connected to the source line 26. A
dielectric layer 53 overlies the source line 26, bottom electrode 52 and substrate 50. The gate line 24 is deposited on dielectric layer 53 and is ~ormed of Chromium.
s A gate insulating layer 54 formed of SiO2 or SiN~ overlies the gate line 24 and dielectric layer 53. Deposited on the gate insulating layer 54 above the gate line 24 is a semiconductor material layer formed of Cadmium Selenide (CdSe) defining the channel 56 of the T~T switch 38.
Contacting the channel 56 are the drain and source electrodes 40 and 42 respectively of the TFT switch 38. A
passivation layer 58 formed of sio2 or Si covers the portion of the channel 56 not covered by the drain and source electrodes.
Above the TFT switch array is the radiation transducer Cs~. The radiation transducer is in the form of a selenium (Se) radiation conversion layer 70 having a thickness of approximately 300~m to 500~m. Above the radiation conversion layer is a top electrode 72 formed of In, Al or Au. The top electrode 72 is coupled to a high potential voltage source 74 to provide the necessary bias to the radiation transducer CSE. The top electrode 72 and the drain electrode 40 form the electrodes of radiation transducer CSE while the drain electrode 40 and bottom electrode 52 form the electrodes of storage capacitor CST.
Although only one pixel 22 is shown, it should be realized that each of the pixels 22 in the array are identical and that the pixels are formed on the substrate 50 simultaneously by depositing appropriate layers on the substrate and etching them as required.
In operation, the top electrode 72 is biased to a high potential by voltage source 74 and the flat panel detector 20 is exposed to radiation, resulting in an AME~1DEOS~EFT
electric field being created in the radiation conversion layer 70 which causes electrons to move towards the top electrode 72 and holes to move towards the drain or pixel electrodes 40. The majority of the holes drift to the drain electrodes where positive charges are accumulated.
While the flat panel detector 20 is being exposed to radiation, the gate lines 24 are suitably maintained to keep the TFT switches 38 in an off-state.
With the TFT switches off, as the drain electrodes 40 accumulate positive charges, negative charges are pulled on to the bottom electrodes 52 from the charge amplifiers 30 via the source lines 26 so that equal and opposite charges appear at the electrodes 40 and 52 constituting the storage capacitors C~.
After the flat panel detector 20 has been exposed to radiation and it is desired to create an image, a bias is applied to each gate line 24 in succession by the gate driver 28 in response to input from the control circuit 29. When a bias is applied to a gate line 24, all of the TFT switches 38 connected to that gate line turn on. This allows the charges held by the bottom electrodes 52 of those pixels to be sensed by the charge amplifiers 30 connected to the source lines 26 ext~n~;ng to those pixels 22. Thus, by biasing the gate lines 24 in succession, a radiation image can be created on a row-by-row basis. The manner in which the charge held by bottom electrodes 52 is sensed will now be described with reference to a single pixel 22.
When the bias is applied to the gate line 24, the TFT switch 38 is conditioned to an on-state. With the TFT switch on, the drain electrode 40 is electrically coupled to the source electrode 42 and hence, to the gate line 24 associated with another row of pixels 22 through the TFT switch 38. At this stage, the other gate line 24 is grounded and therefore, is at a low potential.
When this occurs, the charge held by the drain electrode 40 is discharged through the TFT switch 38 on to the gate line 24 at ground. As this occurs, the negative charge on the bottom electrode 52 pulled from the charge amplifier 30 via source line 26 is released.
This change in charge on the source line 26 is sensed by the charge amplifier 30. Since the charge on the bottom electrode 52 is proportional to the exposure of the radiation transducer CSE to radiation, the change in charge sensed by the charge amplifier 30 is also proportional to the exposure of the radiation transducer to radiation. The charge amplifier 30 in turn generates output representative of the exposure of the radiation transducer CSE to radiation and conveys the output to the analog multiplexer 32.
Referring now to Figure 5, another embodiment of a pixel for use in a flat panel detector for radiation imaging is shown and is generally indicated by reference numeral 122. The pixel 122 is very similar to that shown in the previous embodiment with the exception that the source electrode 142 of TFT switch 138 is connected to a second source line 126', rather than to the gate line 124. In this embodiment, the source lines 126 and 126' associated with the pixel 122 lead to a balanced charge amplifier 130. Because each pixel has two source lines, noise contributed by one source line 126 cancels the noise contributed by the other source line 126' reducing the overall effect of noise. Also, the use of two source lines helps to reduce the contribution of even harmonics generated by the TFT switch 138 as well as to reduce the effects of odd harmonics.
During operation of the pixel 122, after the flat panel detector has been exposed to radiation and the bottom electrode is charged, when the bias is applied to the gate line 124, the charge held by the drain electrode 140 is discharged through TFT switch 138 on to source line 126' where it is sensed by charge amplifier 130. At the same time, the charge on the bottom electrode 5Z is released. The resulting change in charge on the source line 126 is also sensed by the charge amplifier 130. The balanced charge amplifier 130 detects the input from the source lines 126 and 126' and generates an output voltage proportional to the exposure of the pixel 122 to radiation.
Figure 6 shows an x-ray imaging system 200 for tAki~g a radiation image of an object 202. The x-ray imaging system 200 includes a radiation source 204 and a flat panel detector 206. The flat panel detector can include pixels of the type shown in Figures 2 or 5. As can be seen, when an x-ray image of an object is to be taken, the object 202 is placed between the radiation source 204 and the flat panel detector 206 and the object is exposed to x-ray radiation. X-ray radiation passing through the object 204 contacts the flat panel detector 206 allowing for an image of the object to be taken in the manner described previously.
As should be appreciated by those of skill in the art, the present invention allows charges accumulated by the pixel electrodes to be sensed without discharging the charge through TFT switches to the charge amplifiers.
Also, when two source lines are used in each pixel, electronic noise is reduced. Although reference has been made to specific materials forming the various components of the pixels, those of skill in the art will appreciate that other suitable materials can be used. Those of skill in the art will also appreciate that variations and modifications may be made to the present invention without departing from the scope thereof as defined by the appended claims.
Claims (12)
1. A pixel for a radiation imaging flat panel detector comprising:
a radiation transducer to be exposed to incident radiation;
a pixel electrode on one side of said radiation transducer to accumulate a positive charge proportional to the exposure of said radiation transducer to radiation:
a second electrode separated from said pixel electrode by a dielectric and connected to a source line, said pixel and second electrode constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
a radiation transducer to be exposed to incident radiation;
a pixel electrode on one side of said radiation transducer to accumulate a positive charge proportional to the exposure of said radiation transducer to radiation:
a second electrode separated from said pixel electrode by a dielectric and connected to a source line, said pixel and second electrode constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected.
2. A pixel as defined in claim 1 wherein said semiconductor switch is in the form of a thin film transistor having a drain terminal constituting said pixel electrode, a gate terminal connected to a gate line and being responsive to said gating signal received therefrom, and a source terminal connected to said ground potential terminal.
3. A pixel as defined in claim 2 further comprising a charge amplifier connected to said source line for detecting the release of said negative charge.
4. A pixel as defined in claim 3 wherein said ground potential terminal is a second source line, said second source line also being connected to said charge amplifier.
5. A flat panel detector for radiation imaging comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of source lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines upon which gating signals are supplied is succession to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including:
a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharge to allow the charge to be detected.
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of source lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array; and a plurality of gate lines upon which gating signals are supplied is succession to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array, each of said pixels including:
a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode; and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharge to allow the charge to be detected.
6. A flat panel detector as defined in claim 5 wherein said semiconductor switches are in the form of thin film transistors and wherein said pixels and gate and source lines are formed on a common substrate.
7. A flat panel detector as defined in claim 6 wherein said low potential terminal is a gate line interconnecting the pixels of a different row.
8. A flat panel detector as defined in claim 6 further including an array of charge amplifiers, each connected to one of said source lines to detect the charge thereon.
9. A flat panel detector as defined in claim 7 further including a gate driver to supply gating signal to said sate lines in succession to allow the charges accumulated by said pixels to be detected on a row-by-row basis.
10. A flat panel detector as defined in claim 6 wherein said ground potential terminal is a second source line associated with said pixel, said charge being detected by sensing both source lines.
11. A flat panel detector as defined in claim 10 further including an array of charge amplifiers, each connected to both of the source lines interconnecting the individual ones of one of the rows or columns of said array to detect the charges thereon.
12. A radiation imaging system including a radiation source and a flat panel detector, said flat panel detector comprising:
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array;
a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array;
an array of charge amplifiers, each connected to one of said source lines to detect the charge thereon;
and a gate driver to supply gating signal to said gate lines in succession to allow the charges accumulated by said pixels to be detected on a row-by-row basis, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode;
and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected by said charge amplifier.
a radiation transducer including a radiation conversion layer and an electrode on one side of said radiation conversion layer;
an array of pixels arranged in rows and columns on the other side of said radiation conversion layer;
a plurality of sources lines upon which charges accumulated by said pixels can be sensed, each of said source lines connecting the pixels in individual ones of one of said rows or columns of said array;
a plurality of gate lines upon which gating signals are supplied to allow accumulated charges to be sensed, each of said gate lines connecting the pixels in individual ones of the other of said rows or columns of said array;
an array of charge amplifiers, each connected to one of said source lines to detect the charge thereon;
and a gate driver to supply gating signal to said gate lines in succession to allow the charges accumulated by said pixels to be detected on a row-by-row basis, each of said pixels including: a pixel electrode to accumulate positive charge as a result of hole drift in said radiation conversion layer occurring upon exposure of said radiation transducer to radiation and when said electrode is biased; a second electrode separated from said pixel electrode by a dielectric and connected to one of said source lines, said pixel and second electrodes constituting a storage capacitor, said second electrode developing a negative charge equal to the magnitude of the positive charge accumulated by said pixel electrode;
and a semiconductor switch coupled between said pixel electrode and a ground potential terminal, said semiconductor switch being responsive to a gating signal to connect electrically said pixel electrode to said ground potential terminal to discharge said pixel electrode thereon, said second electrode releasing said negative charge on said source line when said pixel electrode discharges to allow the charge to be detected by said charge amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002228117A CA2228117A1 (en) | 1995-07-31 | 1995-07-31 | Flat panel detector for radiation imaging and pixel for use therein |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002228117A CA2228117A1 (en) | 1995-07-31 | 1995-07-31 | Flat panel detector for radiation imaging and pixel for use therein |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2228117A1 true CA2228117A1 (en) | 1997-02-13 |
Family
ID=4162038
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002228117A Abandoned CA2228117A1 (en) | 1995-07-31 | 1995-07-31 | Flat panel detector for radiation imaging and pixel for use therein |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2228117A1 (en) |
-
1995
- 1995-07-31 CA CA002228117A patent/CA2228117A1/en not_active Abandoned
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5396072A (en) | X-ray image detector | |
| US5929449A (en) | Flat panel detector for radiation imaging with reduced electronic noise | |
| EP0897597B1 (en) | High resolution flat panel for radiation imaging | |
| JP3457676B2 (en) | Radiation imaging panel | |
| US5930591A (en) | High resolution, low voltage flat-panel radiation imaging sensors | |
| US6172369B1 (en) | Flat panel detector for radiation imaging with reduced trapped charges | |
| EP0722188B1 (en) | Image capture panel using a solid state device | |
| US5789737A (en) | High dynamic range segmented pixel sensor array | |
| EP0437041B1 (en) | Solid-state radiation sensors | |
| US6232606B1 (en) | Flat panel detector for radiation imaging and pixel for use therein | |
| EP0804807A1 (en) | Flat panel imaging device | |
| EP1540730A2 (en) | Ganged detector pixel, photon/pulse counting radiation imaging device | |
| EP1079437B1 (en) | Radiation detecting apparatus | |
| JPH0518265B2 (en) | ||
| EP0744085B1 (en) | Electromagnetic radiation imaging device using thin film transistors | |
| US20110284749A1 (en) | Radiation detector | |
| US6486470B2 (en) | Compensation circuit for use in a high resolution amplified flat panel for radiation imaging | |
| JP4026377B2 (en) | Radiation detector | |
| JP4508429B2 (en) | Sensor matrix | |
| CA2228117A1 (en) | Flat panel detector for radiation imaging and pixel for use therein | |
| JP4217443B2 (en) | Radiation image capturing apparatus, manufacturing method thereof, and imaging circuit board | |
| JPH11510313A (en) | Flat panel detector for radiation image formation and pixels used therein | |
| JP4066531B2 (en) | Radiation detector | |
| US20120025190A1 (en) | Radiation detector | |
| CA2228065A1 (en) | Flat panel detector for radiation imaging with reduced electronic noise |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |