CA2497465A1 - Pixel circuit for radiation detection - Google Patents
Pixel circuit for radiation detection Download PDFInfo
- Publication number
- CA2497465A1 CA2497465A1 CA002497465A CA2497465A CA2497465A1 CA 2497465 A1 CA2497465 A1 CA 2497465A1 CA 002497465 A CA002497465 A CA 002497465A CA 2497465 A CA2497465 A CA 2497465A CA 2497465 A1 CA2497465 A1 CA 2497465A1
- Authority
- CA
- Canada
- Prior art keywords
- pixel
- circuit
- tft
- voltage
- charge
- 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 abstract description 10
- 238000001514 detection method Methods 0.000 title abstract description 8
- 238000005516 engineering process Methods 0.000 abstract description 7
- 230000003321 amplification Effects 0.000 abstract description 6
- 238000003199 nucleic acid amplification method Methods 0.000 abstract description 6
- 238000003491 array Methods 0.000 abstract description 3
- 230000015556 catabolic process Effects 0.000 abstract description 3
- 238000006731 degradation reaction Methods 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 229910021417 amorphous silicon Inorganic materials 0.000 description 8
- 230000010354 integration Effects 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 4
- 239000011669 selenium Substances 0.000 description 4
- 238000013459 approach Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920005591 polysilicon Polymers 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 208000004434 Calcinosis Diseases 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000004195 computer-aided diagnosis Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000009607 mammography Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910021424 microcrystalline silicon Inorganic materials 0.000 description 1
- 229910021423 nanocrystalline silicon Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- -1 organic Polymers 0.000 description 1
- 238000002601 radiography Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- G01T1/247—Detector read-out circuitry
-
- 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
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
- H04N25/77—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
- H04N25/772—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components comprising A/D, V/T, V/F, I/T or I/F converters
- H04N25/773—Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components comprising A/D, V/T, V/F, I/T or I/F converters comprising photon counting circuits, e.g. single photon detection [SPD] or single photon avalanche diodes [SPAD]
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- General Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electromagnetism (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Computer Hardware Design (AREA)
- Health & Medical Sciences (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Molecular Biology (AREA)
- High Energy & Nuclear Physics (AREA)
- Toxicology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Measurement Of Radiation (AREA)
Abstract
The present invention relates to an on-pixel readout circuit for detectors, and more particularly to an active pixel sensor (APS) circuit for radiation detection, capable of providing stable and predictable on-pixel amplification in the presence of device degradation and/or mismatch, and variation in environmental factors like temperature and mechanical strain. This invention is applicable to various detector technologies such as flat panel imagers, sensor arrays, x-ray detectors, CMOS cameras, etc.
Description
FIELD OF THE INVENTION
The present invention relates to an on-pixel readout circuit for detectors, and more particularly to an active pixel sensor (APS) circuit for radiation detection, capable of providing stable and predictable on-pixel amplification in the presence of device degradation and/or mismatch, and variation in environmental factors like temperature and mechanical strain. This invention is applicable to various detector technologies such as flat panel imagers, sensor arrays, x-ray detectors, CMOS cameras, etc.
BACKGROUND OF THE INVENTION
The present invention relates to an on-pixel readout circuit for detectors, and more particularly to an active pixel sensor (APS) circuit for radiation detection, capable of providing stable and predictable on-pixel amplification in the presence of device degradation and/or mismatch, and variation in environmental factors like temperature and mechanical strain. This invention is applicable to various detector technologies such as flat panel imagers, sensor arrays, x-ray detectors, CMOS cameras, etc.
BACKGROUND OF THE INVENTION
2. Description of the Prior Art The following description will be based on an example of a flat panel x-ray imaging system, although the invention is not restricted to this invention.
Flat-panel detectors have gained significant interest recently in view of their ability to provide an immediate, high quality radiographs after the exposure. They require less handling, more convenient management, immediate image viewing, computer aided analysis and more convenient storage on computer disks rather than archive film stacks [1].
Flat-panel detectors convert incident radiation images to charge images. In the case of x-rays, for instance, the radiated x-rays may be converted to charge directly [2] by using an x-ray sensitive photoconductor such as amorphous selenium, a-Se, or indirectly [3] by using a phosphor screen to convert an incident x-ray image to light, which is then converted to a charge distribution. In both approaches the final charge image is stored on the pixel capacitors. This stored image is then read out using a large area integrated circuit backplane usually referred to as active matrix. Active matrix addressing involves a layer of backplane electronics, based on thin-film transistors (TFTs) fabricated using amorphous silicon (a-Si:H), polycrystalline silicon (poly-Si), CMOS, organic, polymer, or other transistor technologies, to provide on-pixel amplification and read out capability in each imaging pixel. In order to utilize the flat panel for reliable radiation detection, it is necessary to decrease the electronic noise or increase the radiation signal. One basic approach to increase the signal to noise ratio would be on-pixel amplification of the input signal, In this approach, the TFTs will act as both analog amplifiers and switches compared to the conventional case where the transistors were used just as switches [3].
However, transistor threshold voltage and mobility instability, and mismatch issues are a major hurdle in flat panel active matrix applications with on-pixel amplification. This is because the amplifying circuits are far more sensitive to TFT instability. As an example of instability, Fig. 1 shows the threshold voltage shift in amorphous silicon TFTs. In a flat panel, the instability would mean that the amplifier gain and the output DC current would vary across the array and/or decrease over time, which is unacceptable.
One solution to this stability problem is to use current programmed pixel circuits.
The circuit shown in Fig. 2 is a current programmed pixel circuit, which automatically compensates for any shift or mismatch in the threshold voltage of the drive TFT to ensure that the output DC current and circuit gain do not decrease over time.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide pixel circuits for radiation detectors, capable of providing stable and predictable on-pixel amplification, despite device degradation and/or mismatch, and change of environmental factors like temperature and mechanical strain.
In order to achieve these goals, a family of pixel circuits for radiation detection is presented. The present invention comprises a plurality transistors in CMOS or thin film technology for amplifying the x-ray generated signal in each pixel of the flat panel. These pixel circuits are automatically capable of compensating shifts and mismatches in the characteristics properties of the transistors in a pixel.
The basic architecture comprises of a plurality of switching transistors, an amplifying transistor, and a sensor for detection of radiation (such as optical signal, x-ray signal, etc.).
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and features of the present invention will become more apparent by the following description of the preferred embodiments with reference to the attached drawings. Although they directly apply to TFT
circuits in amorphous silicon (a-Si) flat panel technology, they can be readily extended to other technologies like polysilicon, organic, polymer, CMOS, etc. for visible and x-ray detection.
Fig. 1- Threshold voltage shift as a function of stress voltage of a discrete a-Si TFT.
Fig. 2- Schematic of current mode active pixel sensor circuit with TFT
parameter compensation capability along with the driving waveforms.
Fig. 3- Output current versus threshold voltage of the AMP TFT presented here.
Fig. 4- Input-output transfer characteristics demonstrating the current gain.
Fig. 5- An array structure of the pixel presented in Fig. 2.
Fig. 6- Another version of the circuit in Fig. 2 along with the driving waveforms.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 2 and Fig. 2 show the presented pixel circuit along with its control signals. It comprises four transistors T1, T2, READ and AMP, a storage capacitor CSroRe and a radiation sensor (SENSOR). The pixel circuit is connected to a common ground, a select line (SELECT), an input bias signal fine (IBIAS) and an output signal line. The four transistors T1, T2, READ and AMP can be a-Si:H, nano/micro crystalline silicon, poly silicon, organic thin-film transistors (TFT), transistors in standard CMOS, or other technologies. AMP is the amplifying transistor while the other three act as switches. Central to the circuit is a common source circuit comprising of AMP and READ TFTs, which produces a current output to drive an external charge amplifier. The active matrix array architecture is assumed to be column-parallel, i.e., one charge amplifier per column so that an entire row can be read out simultaneously. The APS circuit operates in three modes:
Programming: the SELECT control signal becomes high; consequently the pixel is selected and transistors T1 and T2 turn on. If we assume that initially there is no charge on the storage capacitance (CsroRE), the AMP TFT is off and therefore the constant programming current Ig,AS will flow through T1 and T2, which charges up the storage capacitor. Simultaneously, the drain-source current of the AMP TFT will increase until eventually it becomes equal to IB~AS. After that there would be no further increase in the voltage of CSTORE, which is the same as the voltage across the gate-source terminal of the AMP TFT. In this stage, the AMP
TFT operates in its saturation mode where the current-voltage is given by ~ _ ~~.U ~Ci '~ W ymn I vGS -vT ~~ - K I\VGS VT la CU ~' e(t (1) Here, ,u~ is the effective device mobility, ~' is a material parameter, C; the gate dielectric capacitance, a a coefficient that ranges between 2 and 2.4, Ysat - ~~ + ~~~DS
(2) and ~, is the channel length modulation parameter. The voltage across CgTORE
stabilizes at the point when all of IB~AS flows through T2 and the AMP TFT, and none through T1. This process is independent of the parameters of the AMP
TFT.
Integration: The SELECT line is switched to low. The voltage stored in CSTORE
remains constant, except for the initial drop due to charge feed-through stemming from the gate-source capacitance of T1 when it turns off.
Subsequently, the integration starts, during which the incident x-ray photons will generate electron-hole pairs in the x-ray sensitive a-Se layer. These electron-hole pairs are separated and driven by an applied electric field to the surfaces of the photoconductor where they will form a latent charge image. In the integration period T,N,. , the input signal, h v , generates carriers that discharge CSTORE bY
~QP and increase its potential by a small-signal voltage of v,n Readout mode: After integration, the READ TFT is turned ON. As a result, a common source topology in which AMP TFT is the amplifying transistor and READ TFT acts as a passive resistor, will be constructed. The output current of the circuit at this point would be I BIAS + gm X vin
Flat-panel detectors have gained significant interest recently in view of their ability to provide an immediate, high quality radiographs after the exposure. They require less handling, more convenient management, immediate image viewing, computer aided analysis and more convenient storage on computer disks rather than archive film stacks [1].
Flat-panel detectors convert incident radiation images to charge images. In the case of x-rays, for instance, the radiated x-rays may be converted to charge directly [2] by using an x-ray sensitive photoconductor such as amorphous selenium, a-Se, or indirectly [3] by using a phosphor screen to convert an incident x-ray image to light, which is then converted to a charge distribution. In both approaches the final charge image is stored on the pixel capacitors. This stored image is then read out using a large area integrated circuit backplane usually referred to as active matrix. Active matrix addressing involves a layer of backplane electronics, based on thin-film transistors (TFTs) fabricated using amorphous silicon (a-Si:H), polycrystalline silicon (poly-Si), CMOS, organic, polymer, or other transistor technologies, to provide on-pixel amplification and read out capability in each imaging pixel. In order to utilize the flat panel for reliable radiation detection, it is necessary to decrease the electronic noise or increase the radiation signal. One basic approach to increase the signal to noise ratio would be on-pixel amplification of the input signal, In this approach, the TFTs will act as both analog amplifiers and switches compared to the conventional case where the transistors were used just as switches [3].
However, transistor threshold voltage and mobility instability, and mismatch issues are a major hurdle in flat panel active matrix applications with on-pixel amplification. This is because the amplifying circuits are far more sensitive to TFT instability. As an example of instability, Fig. 1 shows the threshold voltage shift in amorphous silicon TFTs. In a flat panel, the instability would mean that the amplifier gain and the output DC current would vary across the array and/or decrease over time, which is unacceptable.
One solution to this stability problem is to use current programmed pixel circuits.
The circuit shown in Fig. 2 is a current programmed pixel circuit, which automatically compensates for any shift or mismatch in the threshold voltage of the drive TFT to ensure that the output DC current and circuit gain do not decrease over time.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide pixel circuits for radiation detectors, capable of providing stable and predictable on-pixel amplification, despite device degradation and/or mismatch, and change of environmental factors like temperature and mechanical strain.
In order to achieve these goals, a family of pixel circuits for radiation detection is presented. The present invention comprises a plurality transistors in CMOS or thin film technology for amplifying the x-ray generated signal in each pixel of the flat panel. These pixel circuits are automatically capable of compensating shifts and mismatches in the characteristics properties of the transistors in a pixel.
The basic architecture comprises of a plurality of switching transistors, an amplifying transistor, and a sensor for detection of radiation (such as optical signal, x-ray signal, etc.).
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and features of the present invention will become more apparent by the following description of the preferred embodiments with reference to the attached drawings. Although they directly apply to TFT
circuits in amorphous silicon (a-Si) flat panel technology, they can be readily extended to other technologies like polysilicon, organic, polymer, CMOS, etc. for visible and x-ray detection.
Fig. 1- Threshold voltage shift as a function of stress voltage of a discrete a-Si TFT.
Fig. 2- Schematic of current mode active pixel sensor circuit with TFT
parameter compensation capability along with the driving waveforms.
Fig. 3- Output current versus threshold voltage of the AMP TFT presented here.
Fig. 4- Input-output transfer characteristics demonstrating the current gain.
Fig. 5- An array structure of the pixel presented in Fig. 2.
Fig. 6- Another version of the circuit in Fig. 2 along with the driving waveforms.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 2 and Fig. 2 show the presented pixel circuit along with its control signals. It comprises four transistors T1, T2, READ and AMP, a storage capacitor CSroRe and a radiation sensor (SENSOR). The pixel circuit is connected to a common ground, a select line (SELECT), an input bias signal fine (IBIAS) and an output signal line. The four transistors T1, T2, READ and AMP can be a-Si:H, nano/micro crystalline silicon, poly silicon, organic thin-film transistors (TFT), transistors in standard CMOS, or other technologies. AMP is the amplifying transistor while the other three act as switches. Central to the circuit is a common source circuit comprising of AMP and READ TFTs, which produces a current output to drive an external charge amplifier. The active matrix array architecture is assumed to be column-parallel, i.e., one charge amplifier per column so that an entire row can be read out simultaneously. The APS circuit operates in three modes:
Programming: the SELECT control signal becomes high; consequently the pixel is selected and transistors T1 and T2 turn on. If we assume that initially there is no charge on the storage capacitance (CsroRE), the AMP TFT is off and therefore the constant programming current Ig,AS will flow through T1 and T2, which charges up the storage capacitor. Simultaneously, the drain-source current of the AMP TFT will increase until eventually it becomes equal to IB~AS. After that there would be no further increase in the voltage of CSTORE, which is the same as the voltage across the gate-source terminal of the AMP TFT. In this stage, the AMP
TFT operates in its saturation mode where the current-voltage is given by ~ _ ~~.U ~Ci '~ W ymn I vGS -vT ~~ - K I\VGS VT la CU ~' e(t (1) Here, ,u~ is the effective device mobility, ~' is a material parameter, C; the gate dielectric capacitance, a a coefficient that ranges between 2 and 2.4, Ysat - ~~ + ~~~DS
(2) and ~, is the channel length modulation parameter. The voltage across CgTORE
stabilizes at the point when all of IB~AS flows through T2 and the AMP TFT, and none through T1. This process is independent of the parameters of the AMP
TFT.
Integration: The SELECT line is switched to low. The voltage stored in CSTORE
remains constant, except for the initial drop due to charge feed-through stemming from the gate-source capacitance of T1 when it turns off.
Subsequently, the integration starts, during which the incident x-ray photons will generate electron-hole pairs in the x-ray sensitive a-Se layer. These electron-hole pairs are separated and driven by an applied electric field to the surfaces of the photoconductor where they will form a latent charge image. In the integration period T,N,. , the input signal, h v , generates carriers that discharge CSTORE bY
~QP and increase its potential by a small-signal voltage of v,n Readout mode: After integration, the READ TFT is turned ON. As a result, a common source topology in which AMP TFT is the amplifying transistor and READ TFT acts as a passive resistor, will be constructed. The output current of the circuit at this point would be I BIAS + gm X vin
(3) Where gm is the transconductance of AMP TFT and v,n is the small signal voltage generated during the integration period.
The on-pixel gain of the pixel is the change in the output current dlo"T , with respect to the incident x-ray illumination h v g = d ~~our ~ - d ~~QP ~ , d ~~V~ ~ d ~01 ovr d~hv~ d~hv~ d~~QP~~ d~tlV~~
The on-pixel gain of the pixel is the change in the output current dlo"T , with respect to the incident x-ray illumination h v g = d ~~our ~ - d ~~QP ~ , d ~~V~ ~ d ~01 ovr d~hv~ d~hv~ d~~QP~~ d~tlV~~
(4) Here, dQP is the input charge signal due to pixel irradiation and dv~ is the corresponding change in the gate voltage of the AMP TFT. The value of the first term is identified by the characteristics of the x-ray detector and the amount of change in the charge of CSroRE it gives with changing h v . The second term depends upon the voltage change across CsroRE due to change in its charge dQp = dYG.CSTORE
(5) For the last term to be constant, the linear small signal condition on the AMP
TFT
should be imposed during operation d Y~ « 2(V~ - Vr
TFT
should be imposed during operation d Y~ « 2(V~ - Vr
(6) Here Y~ and VT are the gate bias voltage of the AMP TFT and its threshold voltage, respectively.
As shown in Fig. 2, the output current of the APS circuit will flow through an off-chip charge amplifier where it can be converted into voltage and further amplified. Assuming constantdIoUT, the change of the charge amplifier output voltage dVour will be Ts dVOUT - 1 j~OUTdt - ~OUTTS
O'mdVc ~T'S ~gm~in ~Ts - CF - CF
As shown in Fig. 2, the output current of the APS circuit will flow through an off-chip charge amplifier where it can be converted into voltage and further amplified. Assuming constantdIoUT, the change of the charge amplifier output voltage dVour will be Ts dVOUT - 1 j~OUTdt - ~OUTTS
O'mdVc ~T'S ~gm~in ~Ts - CF - CF
(7) where v;n represents the small signal voltage at the gate of the AMP TFT due to x-ray induced electron-hole pairs and TS is the pulse width during the Readout mode. Using (4) and (7), the total charge gain G,~, defined as the change in the charge across the feedback capacitance of the charge amplifier over the change in the charge of pixel capacitance is ~Qour W ouT ~Ts ~ W our y's Gror = _ ~QP ~~P ~yGCSTORE
_ (g,n .TS
CsroRE
_ (g,n .TS
CsroRE
(8) Using (7) and (8), the charge gain G,oi can be related to the voltage gain fli, ~' ~ vOUT ~ vin ~ a$
CF
Gu~r = Av .
CsroRs
CF
Gu~r = Av .
CsroRs
(9) Fig. 6 is another version of the presented method. The major difference is that in the readout mode the circuit becomes a common-source with active load.
Consequently, this circuit has higher voltage gain compared to the circuit in Fig.2.
References:
1. Chan HP, Doi K, Galhotra S, Vborny CJ, MacMahon H, Jokich PM, " Image feature analysis and Computer-Aided Diagnosis in Digital Radigraphy. 1.
Automated Detection of Microcalcifications in Mammography."MedPhys 14:538-548, 1987.
2. W. Zhao and J. A. Rowlands, "X-ray imaging using amorphous selenium:
Feasibility of a flat panel self-scanned detector for digital radiography,"
Med. Phys. 22, 1595-1604, 1995.
3. L. E. Antonuk, J. Boudry, W. Huang, J. L. McShan, E. J. Morton, J.
Yorkston, M. J. Longo, and R. A. Street, "Demonstration of megavoltage and diagnostic x-ray imaging with hydrogenated amorphous silicon arrays,"
Med. Phys. 19, 1455-1466, 1992.
Consequently, this circuit has higher voltage gain compared to the circuit in Fig.2.
References:
1. Chan HP, Doi K, Galhotra S, Vborny CJ, MacMahon H, Jokich PM, " Image feature analysis and Computer-Aided Diagnosis in Digital Radigraphy. 1.
Automated Detection of Microcalcifications in Mammography."MedPhys 14:538-548, 1987.
2. W. Zhao and J. A. Rowlands, "X-ray imaging using amorphous selenium:
Feasibility of a flat panel self-scanned detector for digital radiography,"
Med. Phys. 22, 1595-1604, 1995.
3. L. E. Antonuk, J. Boudry, W. Huang, J. L. McShan, E. J. Morton, J.
Yorkston, M. J. Longo, and R. A. Street, "Demonstration of megavoltage and diagnostic x-ray imaging with hydrogenated amorphous silicon arrays,"
Med. Phys. 19, 1455-1466, 1992.
Claims
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002497465A CA2497465A1 (en) | 2005-02-28 | 2005-02-28 | Pixel circuit for radiation detection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002497465A CA2497465A1 (en) | 2005-02-28 | 2005-02-28 | Pixel circuit for radiation detection |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2497465A1 true CA2497465A1 (en) | 2006-08-28 |
Family
ID=36938913
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002497465A Abandoned CA2497465A1 (en) | 2005-02-28 | 2005-02-28 | Pixel circuit for radiation detection |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2497465A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014033112A3 (en) * | 2012-09-03 | 2014-04-17 | Siemens Aktiengesellschaft | Dose measurement device |
| WO2014143760A1 (en) * | 2013-03-15 | 2014-09-18 | Carestream Health, Inc. | Radiographic imaging detector using voltage conversion on glass |
| EP4220202A3 (en) * | 2022-01-05 | 2023-11-15 | InnoLux Corporation | Electronic device |
-
2005
- 2005-02-28 CA CA002497465A patent/CA2497465A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014033112A3 (en) * | 2012-09-03 | 2014-04-17 | Siemens Aktiengesellschaft | Dose measurement device |
| WO2014143760A1 (en) * | 2013-03-15 | 2014-09-18 | Carestream Health, Inc. | Radiographic imaging detector using voltage conversion on glass |
| EP4220202A3 (en) * | 2022-01-05 | 2023-11-15 | InnoLux Corporation | Electronic device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8642970B2 (en) | Radiographic image detecting apparatus and radiographic image capturing system | |
| US8488037B2 (en) | Photoelectric conversion apparatus and photoelectric conversion system having the apparatus | |
| CA2585375C (en) | High gain digital imaging system | |
| CN103297716B (en) | Image pickup units and image pickup display system | |
| KR102065807B1 (en) | Charge injection compensation for digital radiographic detectors | |
| US9500752B2 (en) | Pixel architecture for imaging devices | |
| EP3764637B1 (en) | Image sensor and imaging system comprising the same | |
| WO2016084454A1 (en) | Radiation detector | |
| EP2025005A2 (en) | A cmos linear voltage/current dual-mode imager | |
| US20080290253A1 (en) | Image Sensor | |
| JP2001285724A (en) | Charge amount detection circuit | |
| CA2497465A1 (en) | Pixel circuit for radiation detection | |
| US11271029B2 (en) | Image sensor and imaging system comprising the same | |
| US7268607B2 (en) | Integrating capacitance circuitry for an integrating amplifier and related method | |
| EP3354010A1 (en) | Pixel circuit | |
| CA2521145A1 (en) | Pixel circuit for radiation detection | |
| Izadi et al. | Low-noise pixel architecture for advanced diagnostic medical x-ray imaging applications | |
| Izadi et al. | Noise optimisation analysis of an active pixel sensor for low-noise real-time X-ray fluoroscopy | |
| CA2525510A1 (en) | Pixel circuit for radiation detectors | |
| Maolinbay et al. | Design and performance of a low noise, 128-channel ASIC preamplifier for readout of active matrix flat-panel imaging arrays | |
| Safavian et al. | Investigation of gain non-uniformities in the two TFT current programmed amorphous silicon active pixel sensor for fluoroscopy, chest radiography, and mammography tomosynthesis applications | |
| Rankov et al. | A novel correlated double sampling poly-Si circuit for readout systems in large area X-ray sensors | |
| Taghibakhsh et al. | Amplified pixel sensor architectures for low dose computed tomography using silicon thin film technology | |
| Safavian et al. | Characterization of current programmed amorphous silicon active pixel sensor readout circuit for dual mode diagnostic digital x-ray imaging | |
| Taghibakhsh et al. | High resolution amplified pixel sensor architectures for large area digital mammography tomosynthesis |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |