JP4266236B2 - Flat detector - Google Patents

Description

  The present invention relates to a flat detector used in, for example, an X-ray diagnostic apparatus.

  Several conventional X-ray solid state flat detectors employing a direct conversion method or an indirect conversion method have been proposed as conventional examples of flat detectors used in X-ray diagnostic apparatuses. The former is described in, for example, US Pat. No. 5,319,206, and the latter is described in, for example, US Pat. No. 4,689,487.

  FIG. 1 is a diagram showing a schematic configuration of a direct conversion type X-ray solid state flat detector, and FIG. 2 is a diagram showing a schematic configuration of an indirect conversion type X-ray solid state flat detector.

  These flat panel detectors have means for converting electromagnetic waves (X-rays) into electric charges. For example, in the direct conversion system shown in FIG. 1, X-rays incident on Se (selenium: photoconductor) under a high electric field are charged. Contributes to generation and accumulates in the pixel capacity. In addition, in the indirect conversion type flat detector shown in FIG. 2, X-rays are once converted into light through a chemical substance (scintillation layer shown in FIG. 2) such as an intensifying screen or a CSI crystal, and the action of the photodiode The light intensity is stored in the pixel capacitance as an electric charge.

  Further, the conventional flat panel detector includes means for converting the amount of charge into a voltage, selects the charge accumulated in the pixel by, for example, a switching function of a thin film transistor, and charges (reads out) the selected charge. The voltage output of the amplifier is obtained by transferring to. In addition, there is provided means for converting the voltage output from the charge amplifier obtained as analog into a digital value (for example, ADC (A / D converter) for converting the analog value into a digital value). FIG. 3 shows a configuration for reading a signal (charge) in such a flat detector. The flat panel detector stores a conversion layer that generates charges according to incident electromagnetic waves, pixel electrodes arranged in a two-dimensional matrix that collects charges generated in the conversion layers, and charges collected by the pixel electrodes. In this way, charge storage elements connected to the respective pixel electrodes and readout means for reading out charge information stored in the charge storage elements are provided. The reading means electrically connects the switching elements (for example, thin film transistors) connected to the charge storage elements and the TFT gates in the same row so that the charge information connected to the charge storage elements can be read out. Electrically connecting the output of the TFTs in the same column to the control signal line for controlling the switching element control means for controlling the On and Off of the switching element in units of rows by supplying a control voltage to the control signal line Output signal lines and selection means for selecting and outputting the output of each output signal line are provided.

  Note that these flat detectors are not limited to X-rays, and can be considered as light flat detectors.

  In the direct conversion type flat panel detector, a metal film electrode is formed above the photoconductor, and it is necessary to supply a high voltage to the metal film. FIG. 4 shows a method of supplying a high voltage according to a conventional example. As shown in the figure, conventionally, the tip (metal part) of the high-voltage supply cable 4 is bonded to the upper electrode 2.

  In such a conventional example, the high-voltage supply cable 4 is bonded on the image detection area, that is, the pixel matrix 1. For this reason, as shown in FIG. 5, the shadow of the tip of the high-voltage supply cable 4 appears as an artifact 7 in the X-ray image 6.

  When such a conventional flat panel detector is used in an X-ray medical diagnosis system, there is a problem that this artifact 7 may be misdiagnosed as an abnormal shadow. In addition, it is desirable that the area other than the pixel area of the flat detector is basically the minimum size and the entire detector size is reduced.

  The present invention has been made in consideration of the above-described circumstances. The purpose of the present invention is to form a region for supplying a high voltage, a region for element inspection, and the like in a region other than the pixel matrix. An object of the present invention is to provide a flat panel detector capable of preventing misdiagnosis when used as a detector of an X-ray diagnostic system without causing artifacts in an image due to the presence of a region.

  In order to solve the above problems and achieve the object, the flat detector of the present invention is configured as follows.

(1) The flat detector of the present invention is generated by the electromagnetic wave-charge converting means that generates a charge corresponding to an incident electromagnetic wave, and the electromagnetic wave-charge converting means on one side of the electromagnetic wave-charge converting means. A pixel electrode matrix in which a plurality of pixel electrodes for collecting charges are arranged in a two-dimensional matrix, storage means for storing charges collected by the pixel electrodes, and readout means for reading out charges stored in the storage means And a side surface provided with a test electrode for inspecting the characteristics of the electromagnetic wave-charge conversion means, and the pixel electrode matrix of the electromagnetic wave-charge conversion means, provided at a position corresponding to a region where the pixel electrode is absent. A via provided on a side surface opposite to the side surface and including a region having the pixel matrix on the opposite side surface side and a region having the inspection electrode on the opposite side surface side Characterized by comprising an application electrodes.

  According to the present invention, an area for supplying a high voltage, an area for element inspection, and the like are formed in an area other than the pixel matrix, so that the presence of these areas does not cause an artifact in the image. Misdiagnosis when used as a detector of an X-ray diagnostic system can be prevented. Further, the compactness of the entire detector is not impaired.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of this embodiment, the same components as those in the conventional example shown in FIGS. 1 to 5 are denoted by the same reference numerals.

(First embodiment)
FIG. 6 is a diagram showing a main configuration of the flat detector according to the first embodiment of the present invention. In the figure, 1 is a pixel electrode matrix in which pixel electrodes 1a are arranged in a two-dimensional matrix, 2 is an upper electrode for applying a high voltage for biasing, and 3 is a photoconductive device that generates charges in response to incident electromagnetic waves. Se 4 has a bias, a bias supply cable for supplying a high voltage to the upper electrode 3, 8 is a peripheral circuit of the flat panel detector, 9 is a fixing jig for fixing the bias supply cable 4, and 13 is glass. It is a substrate.

  This flat detector is manufactured by laminating the pixel electrode 1a on the glass substrate 13, laminating Se3 on the pixel electrode 1a, and laminating the upper electrode 3 on Se3. Note that an insulating protective layer is formed on the upper electrode 3. In addition, the flat detector has a charge storage element connected to each pixel electrode so as to store the charge collected by the pixel electrode, and the charge information stored in the charge storage element can be read out. A thin film transistor (hereinafter referred to as TFT) connected to each storage element, a control signal line for electrically connecting TFT gates in the same row, and an output signal line for electrically connecting outputs of TFTs in the same column are stacked. It is formed using a process. The peripheral circuit 8 includes a switching element control means for controlling the On and Off of the switching elements in units of rows by supplying a control voltage to the control signal line, and a selection means for selecting and outputting the output of each output signal line And.

  As shown in FIG. 6, the flat detector of the present embodiment has a convex region A for supplying a high voltage (bias) voltage to the upper electrode 2 of Se3 in a region other than the pixel matrix 1.

  In order to realize the convex region A, a mask for depositing Se3 and the upper electrode 2 may be formed larger than the pixel matrix 1. The area of the convex region A is limited by the minimum size (indicated by α and β) for connecting the metal portion (wire portion) 5 of the high-voltage supply cable 4. Alternatively, it may be limited by the size (indicated by α ′) of the peripheral circuit 8 such as a signal read amplifier (including a multiplexer) or a gate driving IC. In the present embodiment, the peripheral circuit 8 is disposed in the cutout region of the upper electrode 2 formed on the side of the convex region A, thereby miniaturizing the flat detector.

  The high-voltage supply cable 4 may be lead by the fixing jig 9 and firmly fixed in the vicinity of the convex region A as in the present embodiment. 7A and 7B are views showing the structure of the fixing jig 9. FIG. 7A is a cross-sectional view of the fixing jig 9 seen from the lateral direction, and FIG. 7B is a view seen from the upper side.

  The fixing jig 9 is made of, for example, ABS resin, and is formed with a hole portion 91 having an appropriate slope for guiding the high-voltage supply cable 4 to the convex region A as shown in FIG.

  According to the present embodiment configured as described above, the convex region A for supplying a high voltage (bias voltage) to the upper electrode 2 of Se3 is formed in a region other than the pixel matrix 1. Artifacts are not generated in the image due to the presence of the convex region A, and misdiagnosis when used as a detector of an X-ray diagnostic system can be prevented. Further, the compactness of the entire detector is not impaired.

  Note that the present embodiment can be implemented even if it is modified as follows. FIG. 8 is a view showing a modification of the present embodiment.

  The high voltage supply region, that is, the region where the high voltage supply cable is bonded may be formed near the edge of the pixel matrix 1 as shown in FIG. In this case, the width of the region is limited by the wire diameter (indicated by α) of the high voltage supply cable 4.

  The high voltage supply region may be provided not only at one place of the flat detector but also at a plurality of places. FIG. 9 is a diagram showing such a modification. A region indicated by a region R is a high voltage supply region. In this modification, this high voltage supply area has a total of four locations (upper left corner, lower left corner, upper right corner, lower right corner of the flat detector as shown in the figure). Part is excluded).

  When the detection surface is enlarged, the voltage across the entire surface does not become uniform, and artifacts may occur due to differences in sensitivity (Sensitivity) at each local area of the image area. Providing the supply regions so as to face each other with the pixel matrix 1 in between is preferable because current characteristics on the upper electrode are good. Of course, high voltage regions may be provided at three or two corners of the flat detector, and the number of arrangements is not particularly limited.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the high voltage supply region to the upper electrode of the photoconductor is formed in a region other than the pixel matrix. In the present embodiment, similarly to the high voltage supply region, electrodes for pixel inspection (in particular, TEG (Test Element Group for checking Se characteristics here)) are formed in regions other than the pixel matrix.

  FIG. 10 is a diagram showing a main configuration of a second embodiment of the flat panel detector according to the present invention. In the figure, 1 is a pixel matrix, 2 is an upper electrode, 10 is a TEG (Se-TEG) electrode for checking Se characteristics, and 11 is a terminal for taking out an output signal from the TEG electrode 10. ing.

  As can be seen from the figure, the flat detector of the present embodiment is provided with the TEG electrode 10 in a region other than the pixel matrix 1. The TEG electrode 10 is arranged so that Se3 is sandwiched between the lower part of the upper electrode 2 described in the first embodiment. The Se characteristic can be measured by measuring the current flowing from the upper electrode 2 to the TEG electrode 10 via Se3.

  Further, the area of the TEG electrode 10 is limited by various conditions as in the first embodiment. For example, it is limited by the size of a peripheral circuit (not shown) such as a signal read amplifier (including a multiplexer) or a gate driving IC.

  The plurality of TEG electrodes 10 may be provided at any one of the four corners of the flat panel detector as in the first embodiment. FIG. 11 shows a configuration example in this case. As shown in the figure, a TEG electrode 101 is provided at the upper left corner of the flat panel detector, and an Se-TEG 102 is provided at the lower right corner facing the pixel region. In addition, a high voltage supply region 201 is provided in the lower left corner of the detector, and a high voltage supply region 202 is provided in the upper right corner opposite to the pixel region. As described above, the TEG electrode may be formed below the high voltage supply region. In FIG. 11, Se-TEGs 101 and 102 are used as spare regions for the high voltage supply region.

  According to the present embodiment configured as described above, since the TEG electrode 10 is formed in an area other than the pixel matrix 1, the presence of the TEG electrode 10 does not cause artifacts in the image. Misdiagnosis when used as a detector of a line diagnostic system can be prevented. Further, the compactness of the entire detector is not impaired.

  In addition, this invention is not limited only to embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the summary.

The figure which shows schematic structure of the X-ray solid state flat detector of the direct conversion system which concerns on a prior art example. The figure which shows schematic structure of the X-ray solid state flat detector of the indirect conversion system which concerns on a prior art example. The figure which shows the structure for signal (electric charge) reading in the flat panel detector which concerns on a prior art example. The figure which shows the method of the high voltage supply which concerns on a prior art example. The figure which shows the artifact on the X-ray image which concerns on a prior art example. The figure which shows the principal part structure of 1st Embodiment of the flat detector which concerns on this invention. The figure which shows the structure of the fixing jig which concerns on 1st Embodiment. The figure which shows the 1st modification of 1st Embodiment. The figure which shows the 2nd modification of 1st Embodiment. The figure which shows the principal part structure of 2nd Embodiment of the flat detector which concerns on this invention. The figure which shows the whole structure of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pixel matrix 1a ... Pixel electrode 2 ... Upper electrode 3 ... Se (photoconductor)
DESCRIPTION OF SYMBOLS 4 ... High voltage supply cable 5 ... Metal part 6 ... X-ray image 7 ... Artifact 8 ... Peripheral circuit 9 ... Fixing jig 10 ... TEG electrode 11 ... Se-TEG terminal

Claims (1)

An electromagnetic wave-to-charge converting means for generating an electric charge according to the incident electromagnetic wave;
A pixel electrode matrix in which a plurality of pixel electrodes for collecting charges generated by the electromagnetic wave-charge conversion unit are arranged in a two-dimensional matrix on one side surface of the electromagnetic wave-charge conversion unit;
Accumulating means for accumulating charges collected by the pixel electrode;
Readout means for reading out the electric charge accumulated in the accumulation means;
An inspection electrode for inspecting characteristics of the electromagnetic wave-to-electric charge conversion means provided at a position corresponding to a region without the pixel electrode;
A region of the electromagnetic wave-charge conversion unit that is provided on a side surface that faces the side surface on which the pixel electrode matrix is provided, and that has the pixel matrix on the side surface of the opposing side and a region that has the inspection electrode on the side of the opposing side surface. A flat panel detector comprising: a bias applying electrode provided to include the electrode.

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