WO2018016311A1 - Radiation detector - Google Patents

Abstract

The present invention suppresses deviation in radiation detection performance between a plurality of adjacent semiconductor layers to which a bias voltage is applied and enhances detection accuracy. This radiation detector is provided with: a plurality of detection element modules configured through the two-dimensional arrangement of detection elements that have a semiconductor layer for generating charge through the reception of radiation photons, a common electrode that is formed on one surface of the semiconductor layer and is for applying a bias voltage to the semiconductor layer, and a pixel electrode that is formed on the other surface of the semiconductor layer; a plurality of lead lines for power supply that are arranged at a prescribed interval on the surfaces of the common electrodes of the detection elements included in the detection element modules; and scattered ray removing members that are disposed above the lead lines so as to correspond to the arrangement of the lead lines.

Description

Radiation detector

The present invention avoids performance degradation caused by connecting a lead wire to a common electrode for applying a bias voltage to a semiconductor cell in a radiation detector composed of a plurality of semiconductor cells.

In recent years, development of a photon counting CT (Computed Tomography) apparatus equipped with a detector (photon counting detector) that employs a photon counting method has been underway. Unlike the charge integration type detector employed in the conventional CT apparatus, the photon counting type detector can individually count the radiation photons incident on the detection element. As a result, the energy of each incident radiation photon can be measured, and more information can be obtained as compared with a conventional CT apparatus.

The detection element of the photon counting detector includes a semiconductor layer such as cadmium zinc telluride (CZT) or cadmium telluride (CdTe), and the semiconductor layer generates a charge corresponding to each incident radiation photon. Electrodes for collecting the generated charges are arranged opposite to each other in the semiconductor layer, and a bias voltage is applied. The electrode arranged for charge readout for each pixel functions as an anode. One cathode side functions as a common electrode for a plurality of pixels. In order to apply a voltage to the common electrode, a lead wire for supplying a bias voltage is connected to the common electrode. By applying such a voltage, the charge generated in the semiconductor layer by the incidence of radiation photons can be individually taken out from the electrode for each pixel.

In the detector having such a configuration, there is a problem that the lead wire for supplying the bias voltage is connected to the common electrode without impairing the performance of the detector. Since a metal wire such as a copper wire is used for the lead wire for supplying the bias voltage, when the lead wire is arranged between the semiconductor layer and the radiation source, the lead wire absorbs radiation and the lead wire is arranged. Differences in detection sensitivity occur between the places where they are placed and the places where they are not placed. As a method for avoiding the occurrence of this sensitivity difference, Patent Document 1 discloses a detector configuration in which a bias voltage feeding structure is provided at a position outside the radiation detection effective area.

JP 2005-086059 JP

By the way, in recent CT apparatuses, there is a strong demand for expanding the width of the radiation detector in the body axis direction in order to shorten the imaging time. For this reason, it is necessary to construct a detector having a wider radiation detection effective area. On the other hand, the semiconductor layer used for the detection element of the photon counting detector is generally difficult to construct the required detector area with a single crystal from the viewpoint of ensuring the yield as a crystal and dimensional accuracy. The necessary detector area is secured by arranging a plurality of crystals adjacent to each other.

At that time, as in Patent Document 1, when multiple detectors with bias power supply lead wires arranged outside the radiation detection effective area are arranged adjacent to each other, the bias power supply lead wires obstruct the close placement of the semiconductor layers. Therefore, a dead zone may occur due to the gap between the semiconductor layers, or the lead wire for bias power supply may interfere with the radiation detection effective area of the adjacent semiconductor layer, thereby impairing the radiation detection performance of the adjacent semiconductor layer. Problem arises. Therefore, even if the configuration of Patent Document 1 is directly applied to a photon counting detector in which a plurality of semiconductor detection elements are arranged adjacent to each other, it is difficult to arrange a structure for supplying a bias voltage without impairing radiation detection performance. .

The present invention has been made in view of the above circumstances, and when supplying a bias voltage to a plurality of adjacently arranged semiconductor layers, the difference in radiation detection performance on the radiation detection surface of each detection element is suppressed and detection sensitivity is uniform. The purpose is to improve the performance.

In order to solve the above problems, the present invention provides the following means.

One embodiment of the present invention includes a semiconductor layer that generates a charge by receiving photons of radiation, a common electrode that is formed on one surface of the semiconductor layer and applies a bias voltage to the semiconductor layer, and the other layer of the semiconductor layer. A plurality of detection element modules in which detection elements having pixel electrodes formed on a surface are two-dimensionally arranged, and for power supply arranged at equal intervals on the surface of a common electrode of each detection element included in the detection element module A radiation detector comprising a plurality of lead wires and a scattered radiation removing member provided corresponding to the arrangement of the lead wires is provided.

According to the present invention, when supplying a bias voltage to a plurality of adjacently arranged semiconductor layers, the difference in radiation detection function on the radiation detection surface of each detection element can be suppressed and detection sensitivity uniformity can be improved.

1 is a block diagram showing an outline of an X-ray CT apparatus according to a first embodiment of the present invention. 1 is a perspective view showing a schematic configuration of an X-ray detector of an X-ray CT apparatus according to a first embodiment of the present invention. FIG. 4A is a plan view of the detection element module used in the X-ray detector according to the first embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 5 is an explanatory diagram illustrating an example of a relationship among X-rays irradiated from an X-ray source applied to the X-ray detector according to the first embodiment of the present invention, a scattered radiation removing member, and an X-ray detector. FIGS. 7A and 7B are explanatory diagrams illustrating an example of a relationship between an array of detection elements and pixels of the X-ray detector according to the first embodiment of the present invention. FIGS. The present invention relates to a detection element module used in an X-ray detector according to Modification 1 of the first embodiment of the present invention, in which (A) is a plan view and (B) is a cross-sectional view taken along line AA ′ of (A). . FIG. 5A is a plan view of a detection element module used in an X-ray detector according to a second embodiment of the present invention, and FIG. FIG. 7A is a plan view of a detection element module used in an X-ray detector according to a third embodiment of the present invention, and FIG. The present invention relates to a detection element module used in an X-ray detector according to Modification 1 of the third embodiment of the present invention, in which (A) is a plan view and (B) is a cross-sectional view taken along line AA ′ of (A). . The present invention relates to a detection element module used in an X-ray detector according to a fourth embodiment of the present invention, (A) is a plan view, (B) is a cross-sectional view taken along line AA ′ of (A), (C) (A) is a partially enlarged view of FIG. The present invention relates to a detection element module used in an X-ray detector according to Modification 1 of the fourth embodiment of the present invention, (A) is a plan view, (B) is a cross-sectional view taken along line AA ′ of (A). (C) is a partially enlarged view of (A). The present invention relates to a detection element module used in an X-ray detector according to Modification 2 of the fourth embodiment of the present invention, (A) is a plan view, (B) is a cross-sectional view taken along line AA ′ of (A). (C) is a partially enlarged view of (A). The present invention relates to a detection element module used in an X-ray detector according to a fifth embodiment of the present invention, wherein (A) is a plan view, (B) is a cross-sectional view taken along line AA ′ of (A), and (C). (A) is a partially enlarged view of FIG. The present invention relates to a detection element module used in an X-ray detector according to Modification 1 of the fifth embodiment of the present invention, (A) is a plan view, (B) is a cross-sectional view taken along line AA ′ of (A). (C) is a partially enlarged view of (A). It is explanatory drawing which concerns on the circuit model for demonstrating the circuit setting of a X-ray detector.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The radiation imaging apparatus according to the present invention is based on an X-ray source that irradiates X-rays, a detection unit that two-dimensionally arranges pixels including a plurality of detection elements that detect the X-rays, and a detection signal based on the detection element A signal processing unit that generates an output signal corresponding to the intensity of the X-ray, a signal addition unit, and an image generation unit are provided.

The signal adder generates an X-ray count signal for each pixel by adding the output signals of the detection elements belonging to the pixel. The image generation unit generates an image based on the X-ray count signal. At this time, based on the X-ray counting signal of the processing target pixel and the X-ray counting signal of the pixel located in the vicinity of the processing target pixel, the non-uniformity for estimating the non-uniformity of the X-ray incident distribution of the processing target pixel. A modal estimation unit is provided.

Hereinafter, embodiments of the present invention will be described more specifically.

<First Embodiment>
Hereinafter, as a radiation detector according to the first embodiment of the present invention, an example of a radiation detector applied to, for example, an X-ray CT apparatus will be described with reference to the drawings.

As shown in FIG. 1, the X-ray CT apparatus includes an X-ray source 100, an X-ray detector 111, and a detection unit 104 (described later) of the X-ray source 100 and the X-ray detector 111 that are arranged in a predetermined manner. A gantry rotating unit 101 that rotates about the rotation axis, a bed top plate 103 disposed in the opening of the gantry rotating unit 101, and a signal that processes signals acquired by the X-ray detector 111 in accordance with the operation of the imaging system And a processing unit 112.

For example, an X-ray tube can be applied to the X-ray source 100. The X-ray source 100 emits X-ray photons by colliding an electron beam accelerated by a tube voltage with a target metal such as tungsten or molybdenum and generating X-rays from the collision position (focal point). X-ray photons emitted from the X-ray source 120 are subjected to adjustment of flux and energy distribution by a filter (not shown), and then partly absorbed by the subject 102 according to the substance distribution in the subject. Is detected by the detection unit 104 described later through the subject 102.

The gantry rotation unit 101 has the X-ray source 100 and the detection unit 104 arranged opposite to each other, and rotates around a predetermined rotation axis. An opening into which the subject 102 is inserted is provided at the center of the gantry rotating unit 101, and a bed top plate 103 on which the subject 102 is laid is disposed in the opening. The bed top plate 103 and the gantry rotating unit 101 are relatively movable in a predetermined direction.

The X-ray detector 111 detects the incident X-ray photons, separates them into a plurality of energy ranges and counts them, and the detection unit 104 adopting a photon counting method, and the scattering provided on the X-ray incident side of the detection unit 104 A line removal member 28 (see FIG. 3B) and a signal collection unit 108 that collects a projection image output from the detection unit 104 are provided.

The X-ray photons output by the detection unit 104 are processed in a pulse mode by the signal collection unit 108 and counted. The counting here includes obtaining energy information in addition to counting the detected X-ray photons. If an X-ray scattered by the subject 102 is detected, an undesired signal is generated. Therefore, a scattered radiation removing member 28 is disposed in front of the detection unit 104 when viewed from the X-ray source 100 side, and the scattered X-ray is detected. Is shut off. Details of the detection unit 104 will be described later.

The signal processing unit 112 includes a calculation unit 105 and a control unit 107, performs predetermined calculation processing on the collected signal with respect to the signal collected by the signal collection unit 108, creates a reconstructed image such as a multi-energy image, The generated image is displayed on a display unit (not shown).

Subsequently, the detection unit 104 of the X-ray detector 111 will be described.

As shown in FIG. 2, the detection unit 104 is configured by arranging a predetermined number of detection modules 10 in which a plurality of detection elements 20 are two-dimensionally arranged in the slice direction and the channel direction. The detection element modules are arranged such that the channel direction coincides with the rotation direction of the gantry rotation unit 101 and the slice direction coincides with the rotation axis direction of the gantry rotation unit 111.

As shown in FIG. 3 (B), each detection element 20 included in the detection element module 10 is formed on the semiconductor layer 21 formed on the upper surface of the semiconductor layer 21 and a semiconductor layer 21 that generates a charge by receiving photons of radiation. A common electrode 22 to which a bias voltage is applied and a pixel electrode 23 formed on the lower surface of the semiconductor layer so as to match the pixel pitch are laminated. Each of the detection elements 20 is a so-called photon counting type detection element, detects incident X-ray photons, and performs counting by dividing into, for example, a plurality of energy ranges.

In the present embodiment, the detection elements 20 configured in this way are arranged in four rows as shown in FIG. 3 (A) (hereinafter, each detection element 20 is designated as 20A, 20B, 20C, 20D as necessary. The detection element module 10 is configured by arranging a plurality of power supply lead wires 24 (24A to 24D) at equal intervals on the surface of the common electrode 22 of the four detection elements 20A to 20D.

As shown in FIG. 3A, the lead wires 24 (24A to 24D) are arranged on the surface of the common electrode 22 of each detection element 20 along the longitudinal direction of the detection element module 10, that is, the slice direction in this embodiment. Are arranged at predetermined intervals, and power for applying a bias voltage is supplied to each of the detection elements 20A to 20D.

The semiconductor layer 21 must be adjacently arranged in the rotation direction (channel direction) of the detection unit 104. That is, since the detection element modules 10 are arranged adjacently to form the detection unit 104, the lead wires 24 in each detection element module 10 are generally drawn in the body axis direction (slice direction). Accordingly, in FIG. 3, the lead wires 24A to 24D are for supplying a bias voltage to the common electrode 22 of the detection elements 20A to 20D from a bias voltage application terminal (not shown) below FIG. Wiring.

The lead wire 24A supplies the bias voltage to the detection element 20A, the lead wire 24B supplies the detection element 20B, the lead wire 24C supplies the detection element 20C, and the lead wiring 24D supplies the detection element 20D with a bias voltage. The lead wires 24A to 24D are covered with an insulator 25 such as resin, and come into contact with the common electrode 22 at the contact 26. If a plurality of contacts 26 are provided for each detection element 20, a uniform voltage can be applied.

3 (A) and 3 (B), two lead wires 24 are arranged for each detection element 20, but one lead wire 24 is connected to a plurality of detection elements 20. You may wire.

Further, on the upper surface of the X-ray detection unit 104, a scattered radiation removing member 28 is disposed corresponding to the arrangement of the lead wires 24. As shown in FIG. 3 (A), a one-dimensional slit collimator configured by standing a plurality of plate-like members at predetermined intervals can be applied as the scattered radiation removing member 28. That is, the scattered radiation removing member 28 is composed of a plurality of rectangular plate-like members made of a substance whose main component is molybdenum, tungsten, or the like. The plurality of plate-like members are arranged at equal intervals in the channel direction so that the plate thickness direction of the plate-like member is the channel direction and matches the arrangement position of the lead wires 24.

Since the scattered radiation removing member 28 is arranged, the lead wire 24 is located under the scattered radiation removing member 28 and is therefore covered and hidden by the scattered radiation removing member 28. However, in FIG. 3 to FIG. For convenience, the lead wire 24 located below the scattered radiation removing member 28 is shown.

By disposing the scattered radiation removing member 28 on the X-ray incident surface of the detection unit 104, almost all of the X-ray photons are incident on the region located below the scattered radiation removal member 28 on the X-ray incident surface of the detection unit 104. Disappear. Therefore, substantially, the upper surface region of the X-ray detection unit 104 where the scattered radiation removing member 28 is not disposed is an effective area of the X-ray incident surface.

Thus, by providing the scattered radiation removing member 28 corresponding to the arrangement positions of the lead wires 24A to 24D and on the upper portions of the lead wires 24A to 24D, each lead is provided on the X-ray incident surface of the X-ray detection unit 104. The lines 24A to 24D are located below the scattered radiation removing member 28. Therefore, it is possible to suppress the influence of a change in detection sensitivity due to the presence of the lead wires 24A to 24D in the effective area of the X-ray incident surface of the detection elements 20A to 20D. The lead wires 24A to 24D are arranged and fixed on the lower surface of the scattered radiation removing member 28, so that the vibration of the lead wires 24A to 24D when the detector 111 rotates is suppressed, and the generation of electrical noise is suppressed. There is also an advantage of doing.

The positional relationship of the lead wires 24A to 24D with respect to the lower surface 28a of the scattered radiation removing member 28 will be described in more detail.

As shown in FIG. 4, the aperture width in the channel direction of the plate-like member of the scattered radiation removing member 28 is a predetermined value PE, the distance between the X-ray focal point F and the lower surface 28a of the scattered radiation removing member 28 is D _ASG , the lead The distance in the stacking direction of the detection element between the lines 24A to 24D and the scattered radiation removing member 28 is SY, and the margin in the channel direction between the lead wires 24A to 24D and the scattered radiation removing member 28 is SX.

In this case, by arranging the lead wires 24A to 24D so as to satisfy the following expression (1), the lead wires 24A to 24D are arranged at positions hidden from the focal point F. Unevenness can be suppressed.

PE / 2 / D _ASG <SX / SY (1)
Furthermore, when considering the influence of scattered radiation or the like by the subject, the height of the scattered radiation removing member 28 is set to H, and the lead wires 24A to 24D are arranged so as to satisfy the following expression (2). The lines 24A to 24D can be hidden behind the scattered radiation removing member 28, and unevenness in detection sensitivity due to the lead wires 24A to 24D can be further suppressed.

PE / H <SX / SY (2)
By wiring the lead wires 24A to 24D in this way, the resistance values of the lead wires 24A to 24D are solid wiring (hereinafter simply referred to as “layer wiring” covering the effective area of the X-ray incident surface of the X-ray detector 104). It will be higher than when it is called “solid wiring”. However, since the resistance value of the semiconductor layer 21 is generally very high, about 1 MΩ, an increase in resistance value (for example, several Ω) caused by wiring the lead wires 24A to 24D as described above can be sufficiently ignored.

This can be generally confirmed by the following equation (3) using the resistance value RD of the semiconductor layer 21 and the resistance value RB of the solid wiring.

RB / RD << 1 (3)
Further, it is preferable that the arrangement intervals of the lead wires 24A to 24D coincide with the pitch of pixels for detecting X-ray photons as a unit of the X-ray detection unit 104, or an integer multiple thereof.

The semiconductor layer 21 may be configured to divide the pixel (pixel) P into a plurality of smaller subpixels SP and to count the number of photons for each subpixel in order to improve the photon counting rate. As an example, FIG. 5A shows a case where a pixel is made up of 2 × 2 subpixels, and FIG. 5B shows a case where a pixel is made up of 3 × 3 subpixels.

In the case of FIG. 5A, the lead wires 24A to 24D are arranged every three pixels, and the contact point between the common electrode (not shown) on one pixel (pixel) of the semiconductor layer 21 and the lead wiring 24 is the contact 26, pixel The opening width is PE2. At this time, the pixel is P2, the subpixel is SP, the pixel pitch is DP2, and the subpixel pitch is DS. On the other hand, in the case of FIG. 5B, for the same subpixel SP and subpixel pitch DS, the pixel (pixel) is P3, the pixel pitch is DP3, and the pixel aperture width is PE3. For detectors that can take various pixel configurations in this way, the least common multiple of the number of subpixel divisions that can take the lead spacing (for example, 6 for subpixel division numbers 2 and 3) Thus, it is possible to cope with different subpixel division numbers with the same lead wires 24A to 24D.

In this way, by matching the pitch of the lead wires 24A to 24D with the pixel pitch, even when the pixel is divided into a plurality of sub-pixels, the sensitivity between sub-pixels included in one pixel Unevenness can be suppressed.

In addition, although one lead wire 24 is configured to supply power to one semiconductor layer 21, it may be configured to supply power to a plurality of semiconductor layers from one lead wire.

Thus, according to the present embodiment, the lead wire 24 does not block the incidence of X-rays by making the wiring position of the lead wire 24 substantially coincide with the arrangement position of the scattered radiation removing member 28.
Further, the exposure of the lead wire can be blocked by the scattered radiation removing member 28 by setting the positional relationship between the lead wire 24 and the scattered radiation 28 to the position defined by the above formulas (1) and (2). Therefore, in the detection module 10 composed of a plurality of adjacently arranged detection elements 20, when supplying a bias voltage to the plurality of detection elements 20, that is, the semiconductor layer 21, the radiation detection performance on the radiation detection surface of each detection element 20 is improved. A difference can be suppressed and detection accuracy can be improved.

In the above-described embodiment, the detection element module 10 including the four detection elements 20 has been described. However, the number of detection elements, the number of lead wires, the width, and the shape of the detection element module can be changed as appropriate.

(Modification 1 of the first embodiment)
In the embodiment described above, the scattered radiation removing member 28 has a one-dimensional configuration, but the scattered radiation removing member 28 is not limited to one dimension, and as shown in FIG. 6, plate-like members are arranged in a grid pattern. A two-dimensional rectangular collimator can also be applied. In this case as well, it is preferable that the pitch and shape of the two-dimensional rectangular collimator coincide with the pixel that detects the incident X-ray photons as a unit of the X-ray detection unit 104. By matching the pitch and shape of the two-dimensional rectangular collimator to the pixel, even if the pixel is divided into multiple subpixels, sensitivity variations between subpixels contained in one pixel are suppressed. Can do.

<Second Embodiment>
In the first embodiment described above and the modifications thereof, the example in which the scattered radiation removing member is arranged so as to match the arrangement of the lead wire with respect to the common electrode of the detection element module has been described. This embodiment is different from the above-described embodiment and its modification in that the scattered radiation removing member 28 is used as a part of the power supply member in the same manner as the lead wire to supply power for applying a bias voltage to the common electrode. Different. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 7, the detection unit 104 is configured by arranging a predetermined number of detection element modules 12 in which a plurality of detection elements are two-dimensionally arranged in the slice direction and the channel direction. The detection element modules are arranged such that the channel direction and the rotation direction coincide with each other, and the slice direction and the rotation axis direction coincide with each other.

The detection element module has, for example, four detection elements 20A to 20D arranged in a line. Each detection element 20 receives a photon of radiation and generates a charge, and an upper surface of the semiconductor layer 21. A common electrode 22 that is formed and applies a bias voltage to the semiconductor layer 21 and a pixel electrode 23 formed on the lower surface of the semiconductor layer are stacked. Each of the detection elements 20 is a so-called photon counting type detection element, detects incident X-ray photons, and performs counting by dividing into, for example, a plurality of energy ranges.

Further, a scattered radiation removing member 28 is disposed on the upper surface of the X-ray detection unit 104. As the scattered radiation removing member 28, for example, a two-dimensional rectangular collimator can be applied. The scattered radiation removing member 28 and the common electrode 22 are electrically connected via lead wires 29 (29A to 29D). By doing so, the scattered radiation removing member 28 is used as a part of the wiring material.

That is, the scattered radiation removing member 28 is maintained at the bias voltage from the bias voltage power supply terminal (not shown) through the lead wiring 29. Next, the bias voltage is applied to the common electrodes 22A to 22D of the detection elements 20A to 20D by connecting the scattered radiation removing member 28 and the common electrode 22 of the detection elements 20A to 20D with lead wires 29A, 29B, 29C, and 29D. Can be fed. Here, the lead wires 29A, 29B, 29C, and 29D have been described as examples, but the scattered radiation removing member 28 and the common electrodes 22A to 22D may be connected using a conductive material such as solder.

As described above, according to the present embodiment, since no lead wire is wired on the upper surface of the common electrode of the detection element module, the X-ray detection surface of each detection element does not interfere with the lead wire, and the radiation detection surface of each detection element. It is possible to improve the detection accuracy by suppressing the difference in radiation detection performance.

<Third embodiment>
In the present embodiment, a lead wiring portion in which a plurality of strip-shaped conductive materials having a length from one end to the other end in the longitudinal direction of the detection element module are arranged in order to supply a bias voltage to the common electrode of the detection element module. Is different from the first and second embodiments described above. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The detection unit of the X-ray detector according to the present embodiment is configured by arranging a predetermined number of detection modules 13 in which a plurality of detection elements are two-dimensionally arranged in the slice direction and the channel direction. The detection element modules are arranged such that the channel direction and the rotation direction coincide with each other, and the slice direction and the rotation axis direction coincide with each other.

As shown in FIG. 8, the detection element module 10 includes, for example, four detection elements 20A to 20D arranged in a line, and each detection element 20 receives a photon of radiation and generates a charge. And a common electrode 22 formed on the upper surface of the semiconductor layer 21 for applying a bias voltage to the semiconductor layer 21 and a pixel electrode 23 formed on the lower surface of the semiconductor layer. Each of the detection elements 20 is a so-called photon counting type detection element, detects incident X-ray photons, and performs counting by dividing into, for example, a plurality of energy ranges.

On the upper surface of the detection element module 10, that is, on the surface of the common electrode of each of the detection elements 20A to 20D, a lead wiring portion 31 for applying a power for applying a bias voltage to the common electrode is provided.

The lead wiring section 31 includes a plurality of strip-shaped wirings 30A, 30B, 30C, and 30D made of a strip-shaped conductive material having a length from one end to the other end in the longitudinal direction of the detection element module at equal intervals in the channel direction. The book is arranged. The plate-like wiring 30A feeds a bias voltage to the detection element 20A, the plate-like wiring 30B feeds the detection element 20B, the plate-like wiring 30C feeds the detection element 20C, and the plate-like wiring 30D feeds the detection element 20D.

Further, a conductor sheet 33 having the same material and the same thickness as the plate-like wiring 30 is provided in the gap between each plate-like wiring 30 in the lead wiring portion 31. The conductor sheet 33 is coated with an insulator 25B such as resin. The material of the conductor sheet 33 is preferably the same material as that of the plate-like wirings 30A to 30D, but may be formed of other materials having substantially the same X-ray attenuation characteristics.

Here, since the lead wiring portion 31 plays a role of supplying a predetermined potential to the common electrode 22, it is necessary at the time of inspection of the detection element 20, that is, at the initial stage of preparation of the detection element module 10. At this time, since there is a concern that the detection element 20 has a low yield, if there is a defect in the detection characteristics, the lead wiring portion 31 is peeled off and replaced with another detection element 20, thereby reducing the production yield of the detection element module 10. Can be improved.

On the other hand, the conductor sheet 33 is arranged to suppress unevenness in detection sensitivity. Since the bonding surface of the conductor sheet 33 is large, it is desirable not to bond at the initial stage of the detection element module 10 production, but to adhere after the inspection and arrangement of the detection elements 20, that is, the final stage of the detection element module 10 production. . In consideration of such a process of creating the detection element module 10, the lead wiring portion 31 and the conductor sheet 33 are configured as separate parts, which has an effect of improving the production yield of the detection element module 10.

More specifically, as shown in FIG. 8 (A), the conductor sheet 33 is disposed so as to fill the gap in the lead wiring portion 31. At this time, a slight gap can be provided between the conductor sheet 33 and each of the plate-like wirings 30A to 30D of the lead wiring portion 31 in consideration of an alignment error. However, it is desirable that this gap be equal to or less than the pixel pitch DP.

In the present embodiment, the lead wiring portion 31 and the conductor sheet 33 are coated with an insulator 25A such as a resin for the purpose of easy handling and protection. Furthermore, the conductor sheet 33 and the lead wiring portion 31 have a layer structure as separate parts.

As described above, according to the present embodiment, by providing the conductor sheet 33 in the gap in the lead wiring portion 31, unevenness in X-ray detection sensitivity caused by the lead wiring portion on the X-ray incident surface is greatly suppressed. be able to.

When adopting this configuration, the potential of the conductor sheet 33 can be appropriately selected from the ground and the bias voltage. When the potential of the conductor sheet 33 is set to the ground, it is difficult for a user or the like to contact the bias voltage, which has an effect of improving the safety of the detector.
On the other hand, when the potential of the conductor sheet is set to the bias potential, there is an effect of improving the stability of the lead wiring against the load fluctuation.

(Modification 1 of the third embodiment)
As shown in FIG. 9, in this modification, instead of the conductor sheet provided in the gap between the plate wirings 30 of the lead wiring part 31 in the third embodiment described above, a detection element is provided on the surface of the lead wiring part. A conductor layer 34 that uniformly covers the entire common electrode of the module is provided.

The conductor layer 34 is preferably made of the same material as that of the lead wiring portion 31, but may be made of another material that can obtain an equivalent X-ray attenuation characteristic. The conductive layer may be coated with an insulator 25B such as a resin for the purpose of improving ease of handling and protection. Further, the effect of improving the production yield of the detection element module 10 by coating the lead wiring portion 31 with another insulator 25A to be a separate part is the same as in the third embodiment.

As described above, in the X-ray incident surface of the detection unit 104, unevenness in X-ray detection sensitivity caused by the lead wiring portion can be greatly suppressed.

<Fourth embodiment>
In the present embodiment, in the same manner as the radiation detector in the third embodiment described above, the length from one end to the other end in the longitudinal direction of the detection element module is used to supply a bias voltage to the common electrode of the detection element module. A lead wiring portion in which a plurality of strip-shaped conductive materials having the above are arranged is provided. As shown in FIG. 10, in the present embodiment, the plate-like wiring of the lead wiring portion is a mesh, and the third embodiment described above in that the mesh pattern of the mesh is inclined with respect to the arrangement direction of the detection elements. And different. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 10, the detection element module 10 includes, for example, four detection elements 20A to 20D arranged in a line, and each detection element 20 receives a photon of radiation and generates a charge. And a common electrode 22 that is formed on the upper surface of the semiconductor layer 21 and applies a bias voltage to the semiconductor layer 21, and a pixel electrode 23 that is formed on the lower surface of the semiconductor layer and is provided to match the pixel pitch. It is configured. Each of the detection elements 20 is a so-called photon counting type detection element, detects incident X-ray photons, and performs counting by dividing into, for example, a plurality of energy ranges.

A lead wiring portion 41 that supplies power for applying a bias voltage to the common electrode is provided on the upper surface of the detection element module 10, that is, on the surface of the common electrode of each of the detection elements 20A to 20D.

The lead wiring portion 41 includes strip-shaped conductive materials 42A, 42B, 42C, 42D made of a strip-shaped conductive material having a length extending from one end to the other end in the longitudinal direction of the detection element module 10 in the channel direction, etc. A plurality are arranged at intervals. As shown in FIG. 10, in the present embodiment, four plate-like wirings 42A to 42D are arranged, the plate-like wiring 42A to the detection element 20A, the plate-like wiring 42B to the detection element 20B, The wiring 42C supplies a bias voltage to the detection element 20C, and the plate-like wiring 42D supplies a bias voltage to the detection element 20D. The plate- like wirings 42A, 42B, 42C, and 42D are covered with an insulator 25 such as resin, and contact the common electrode 22 at the contact 26. If a plurality of contacts 26 are provided for each semiconductor layer 21, a voltage can be applied uniformly.

Each plate- like wiring 42A, 42B, 42C, 42D of the lead wiring portion is a mesh in which lead wires having a wiring width W1 are knitted, and the mesh pattern of the mesh is inclined with respect to the arrangement direction of the detection elements. More specifically, as shown in the enlarged view of FIG. 10 (C), the plate-like wiring has a lead wire with a wiring width W1 in the lateral direction (longitudinal direction of the detection module) pitch PX1 in FIG. 10 (A). FIG. 10A shows a mesh shape knitted so as to have a pitch PY1 in the vertical direction (short direction of the detection module) in FIG.

At this time, the amount of change in detection sensitivity between the pixels due to the mesh wiring can be suppressed by adjusting the wiring width W1 and the horizontal pitch PX1 of the mesh wiring or the wiring width W1 and the vertical pitch PY1 of the mesh wiring. it can. For example, by setting the horizontal pitch PX1 and the vertical pitch PY1 to the same size, and setting the wiring width W1 to the vertical pitch PX1, 10% of the horizontal pitch PY1, and the pixel pitch (DP) or less, X-ray incidence The amount of change in the X-ray detection sensitivity caused by the lead wiring portion on the surface can be suppressed to about 20% of the solid wiring.

To generalize this, if the amount of change in the target detection sensitivity is R%,
W1 / PX1 + W1 / PY1 <R% AND W1 <DP (4)
By setting a constant that defines the mesh of the plate wiring so as to satisfy the above, the amount of change in detection sensitivity due to the presence or absence of the lead wiring portion can be suppressed to about R%. In Equation (4), for the sake of simplicity, the amount of change in detection sensitivity is approximated by the amount of change in aperture ratio, and the influence of overlapping portions of mesh portions is ignored.

Incidentally, as in the first embodiment described above, the mesh wiring has a higher resistance value than the solid wiring. However, since the resistance value of the semiconductor layer is generally very high, about 1 MΩ, the increase in resistance value (for example, several Ω) caused by applying the mesh material wiring to the plate-like wiring can be sufficiently ignored. This can be confirmed by the above-described formula (3).

Note that the detection element module shown in FIG. 10 is an example, and the number of detection elements, the width and shape of the mesh of the plate-like wiring, the mesh-like wiring and the detection element connection position, and the like may be changed as appropriate. Further, the end of the mesh wiring may be shunted using a conductor having a wiring width narrower than the pixel pitch, may be opened without being shunted, or may be thinned out within a range that does not significantly impair performance.

(Modification 1 of the fourth embodiment)
In the present embodiment, in the same manner as the radiation detector in the fourth embodiment described above, the length from one end to the other end in the longitudinal direction of the detection element module is used for feeding a bias voltage to the common electrode of the detection element module. And a lead wiring portion in which a plurality of mesh-like plate wirings are arranged. As shown in FIG. 11, in the present embodiment, a total of eight plate-like wirings in the lead wiring portion are arranged. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The plate- like wirings 42A, 42B, 42C, 42D, 42E, 42F, 42G, and 42H of the lead wiring part 41 supply a bias voltage to the common electrodes of the detection elements 20A to 20D from a bias voltage application terminal (not shown). The plate- like wirings 42A and 42B are connected to the detection element 20A, the plate- like wirings 42C and 42D are connected to the detection element 20B, the plate- like wirings 42E and 42F are connected to the detection element 20C, and the plate- like wirings 42G and 42H are A bias voltage is supplied to each of the detection elements 20D. That is, in the detection element module according to this modification, power can be supplied to one detection element by two plate-like wirings.

Also, the lead wiring portion 41 is covered with an insulator 25 such as a resin, and contacts the common electrode 22 at the contact 26. If a plurality of contacts 26 are provided for each semiconductor layer 21, a voltage can be applied uniformly. In FIG. 11, one plate-like wiring is configured to feed power to one semiconductor layer 21, but a configuration is also possible to feed power to a plurality of semiconductor layers from one plate-like wiring.

The plate-like wirings 42A to 42H in the present modification are knitted with lead wires having a predetermined wiring width in the same manner as the plate-like wiring according to the fourth embodiment described above, and the mesh pattern is arranged in the arrangement direction of the detection elements 20A to 20D. It is a mesh inclined with respect to it. More specifically, as shown in the enlarged view of FIG. 11 (C), the plate-like wiring has a lead wire with a wiring width W2 in the horizontal direction (short direction of the detection module) pitch in FIG. 11 (A). PX2 has a mesh shape knitted so as to have a pitch PY2 in the vertical direction (longitudinal direction of the detection module) in FIG.

The amount of change in detection sensitivity due to such mesh-like plate wirings 42A to 42H can be suppressed by adjusting the wiring width W2, the horizontal direction PX2, and the vertical pitch PY2. For example, the relationship between the vertical pitch PX2, the horizontal pitch PY2, the wiring width W2, the pixel pitch (DP), and the amount of change in detection sensitivity with R% is as follows.

W2 / PX2 + W2 / PY2 <R% AND W2 <DP (5)
In Equation (5), for the sake of simplicity, the amount of change in detection sensitivity is approximated by the amount of change in aperture ratio, and the influence of overlapping portions of mesh portions is ignored.

As described above, according to this modification, it is possible to suppress the amount of change in X-ray detection sensitivity caused by the lead wiring portion on the X-ray incident surface. In addition, by dividing the number of plate wirings in the lead wiring portion and connecting to the common electrode of the detection element at a plurality of locations, it is possible to suppress the voltage distribution inside the common electrode and to make power supply redundant. it can.

(Modification 2 of the fourth embodiment)
In this modification, the plate-like wiring 42 of the lead wiring part 41 is a mesh, and the mesh pattern of the mesh is a lattice shape matching the arrangement direction of the detection elements, and the fourth embodiment described above and its modification Different from Example 1. In the following description, the same components as those in the other embodiments described above are denoted by the same reference numerals, and the description thereof is omitted.

The plate-like wiring 42 of the lead wiring portion 41 in the second modification is a grid-like mesh that matches the arrangement direction of the detection elements. As shown in FIG. 12, the mesh-like plate-like wiring is braided with a lead wire having a wiring width W3, and has a horizontal pitch (short direction of the detection module) PX3 and a vertical pitch (longitudinal direction of the detection module) PY3. By adjusting these, it is possible to suppress a change in detection sensitivity due to the mesh-like plate wiring.

For example, the relationship between the vertical pitch PX3, the horizontal pitch PY3, the wiring width W3, the pixel pitch (DP), and the change amount of the detection sensitivity with R% is as follows.

W3 / PX3 + W3 / PY3 <R% AND W3 <DP (6)
In Equation (6), for the sake of simplicity, the amount of change in the detection sensitivity is approximated by the amount of change in the aperture ratio, and the influence of the overlapping portion of the mesh portion is ignored.

Thus, according to this modification, the amount of change in X-ray detection sensitivity caused by the lead wiring portion on the X-ray incident surface can be suppressed, and the wiring pattern creation cost of the plate-like wiring can be reduced. effective.

<Fifth Embodiment>
The present embodiment includes a lead wiring portion that is uniformly arranged on the surface of the detection element module in order to supply a bias voltage to the common electrode of the detection element module. In the present embodiment, as shown in FIG. 13, the lead wiring portion includes a plurality of lead wires each having a length extending from one end to the other end in the longitudinal direction, and each lead wire is formed on the surface of the common electrode. Arranged at intervals. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The detection element module 10 includes, for example, four detection elements 20A to 20D arranged in a line. Each detection element 20 receives a photon of radiation and generates a charge, and an upper surface of the semiconductor layer 21. The common electrode 22 for applying a bias voltage to the semiconductor layer 21 and the pixel electrode 23 formed on the lower surface of the semiconductor layer and provided to match the pixel pitch are stacked. Each of the detection elements 20 is a so-called photon counting type detection element, detects incident X-ray photons, and performs counting by dividing into, for example, a plurality of energy ranges.

A lead wiring portion 51 including a plurality of lead wires 52A to 52D for supplying power to the common electrode is provided on the upper surface of the detection element module 10, that is, on the surface of the common electrode of each detection element. As shown in FIG. 13, each of the lead wires 52A to 52D has a length from one end to the other end of the detection element module, and is equidistant from the surface of the common electrode while being inclined with respect to the arrangement direction of the detection elements. The lead wires 52A to 52D are arranged uniformly with respect to the X-ray incident surface of each detection element 20.

The lead wire 52A supplies the bias voltage to the detection element 20A, the lead wire 52B supplies the detection element 20B, the lead wire 52C supplies the detection element 20C, and the lead wiring 52D supplies the bias voltage to the detection element 20D.

As shown in Fig. 13 (C), assuming that the lead wire width W4 and the horizontal direction (short direction of the detection element module) pitch PX4, the amount of change in detection sensitivity due to the placement of the lead wire is the width W4 and the horizontal direction It can be suppressed by adjusting PX4. For example, the relationship between the lateral pitch PX4, the wiring width W4, the pixel pitch (DP), and the change amount of the detection sensitivity with R% is as follows.

W4 / PX4 <R% AND W4 <DP (7)
In Equation (7), for the sake of simplicity, the amount of change in detection sensitivity is approximated by the amount of change in aperture ratio.

The lead wiring HVL is covered with an insulator 25 such as a resin, and contacts the common electrode 22 at the contact 26. If a plurality of contacts 26 are provided for each semiconductor layer 21, a voltage can be applied uniformly.

Further, in FIG. 13, each lead wire (HVL) is configured to supply power to one detection element, but power from one lead wire (HVL) to a plurality of semiconductor elements (D). It can also be wired to supply. In this embodiment, the lead wiring is an oblique wiring, which has an effect of reducing the wiring pattern creation cost.

(Modification 1 of the fifth embodiment)
As shown in FIG. 14, in this modified example, as in the fifth embodiment described above, the lead wiring portion includes a plurality of lead wires having a length from one end to the other end in the longitudinal direction. Lead wires are arranged at equal intervals on the surface of the common electrode. In this embodiment, each lead wire is not inclined and is wired in parallel with the arrangement direction of the detection elements.

As shown in Fig. 14 (C), assuming that the lead wire width W5 and lateral (detection element module short) direction pitch PX5, the amount of change in detection sensitivity due to the placement of the lead wire is the wiring It can be suppressed by adjusting the width W5 and the lateral direction PX5.

For example, the relationship between the vertical pitch PX5, the wiring width W5, the pixel pitch (DP), and the amount of change in detection sensitivity with R% is as follows.

W5 / PX5 <R% AND W5 <DP (8)
In Equation (8), for the sake of simplicity, the amount of change in detection sensitivity is approximated by the amount of change in aperture ratio.

Thus, in this modification, the wiring pattern creation cost can be reduced by wiring the lead wires in an interdigital shape.

The above-described embodiments and modifications thereof are merely examples, and the number of detection elements constituting the detection element module, the width and shape of lead wires and plate-like wiring, the detection element connection position, the material of the conductor sheet, and the like are appropriately changed. can do. Further, it may be combined with periodic wiring. Moreover, when the conductor used for a lead wiring part and a conductor sheet uses aluminum and iron with smaller atomic number besides copper, there exists an effect which makes a sensitivity difference smaller.

Hereinafter, the circuit constant setting will be described.

As shown in FIG. 15, a detection element is constituted by the semiconductor layer 21, the common electrode 22, and the pixel electrode 23, and a voltage VHV is applied to the common electrode 22 using a lead wire 24. A capacitance CVH for stabilization is connected in parallel to the voltage VHV.

At this time, if the current induced in the semiconductor layer 21 by photons is ID, the inductance of the lead wire 24 is LHV as a representative parasitic component, and the equivalent circuit is expressed in consideration of the equivalent series resistance ESR of the stabilizing capacitance. As shown in FIG. In such a circuit, anti-resonance occurs due to a change in the specific frequency of the current ID, and a phenomenon occurs in which the voltage applied to the common electrode 22 fluctuates. The frequency F is expressed by the following equation (9) using the parasitic inductance LHV of the lead wiring 24 and the stabilization capacitance CHV.

That is, when the current ID has this frequency component, the voltage applied to the semiconductor layer 21 varies, and the detector response to photons becomes unstable. Therefore, the parasitic inductance LHV and the stabilization capacitance CHV of the lead wiring 24 are appropriately adjusted so as to be away from the main frequency of the current ID. Examples of the frequency of the current ID are those that occur when the lead wire vibrates due to rotation of the CT scanner and the capacitance changes (1 Hz to 5 Hz), and those that occur when the amount of X-ray attenuation changes depending on the subject (1kHz-10kHz) etc. can be considered.

For these frequencies, when the parasitic inductance of the lead wiring 24 is 100 nH and the stabilization capacitance CHV is 47 μH, the resonance frequency F is 73.4 kHz, which can be separated from the main frequency component of the current ID. As another means, by increasing the equivalent series resistance ESR to some extent (lowering the Q value), it is possible to quickly attenuate the resonance generated at the frequency and suppress the influence of voltage fluctuation.

20, 20A, 20B, 20C, 20D detection element, 21 semiconductor layer, 22 ... common electrode, 23 pixel electrode, 24, 29 lead wiring, 25 insulator, 2 contact, 28 scattered radiation removal member, 30 plate wiring, 31 Lead wiring part, 33 conductor sheet, 34 conductor layer, 41 lead wiring part, 42 plate wiring, 51 lead wiring part, 52 lead wire

Claims (16)

1. A semiconductor layer that generates a charge upon receiving photons of radiation, a common electrode that is formed on one surface of the semiconductor layer and applies a bias voltage to the semiconductor layer, and a pixel electrode that is formed on the other surface of the semiconductor layer A plurality of detection element modules in which detection elements having a two-dimensional array are arranged;
   A plurality of power supply lead wires arranged at predetermined intervals on the surface of the common electrode of each detection element included in the detection element module;
   A radiation detector comprising: a scattered radiation removing member that corresponds to the arrangement of the lead wire and is provided on an upper portion of the lead wire.
2. 2. The radiation detector according to claim 1, wherein the scattered radiation removing member is a one-dimensional collimator having a plurality of plate-like members erected in correspondence with the arrangement of the lead wires.
3. 2. The radiation detector according to claim 1, wherein the scattered radiation removing member is a two-dimensional collimator having plate-like members arranged in a lattice pattern corresponding to the arrangement of the lead wires.
4. 3. The radiation detector according to claim 2, wherein a pitch of the plate-like member coincides with a pitch of pixels of the detection element module.
5. 2. The scattered radiation removing member forms a grid with a plurality of channel direction plate materials arranged in correspondence with the lead wire arrangement and a slice direction plate material orthogonal to the channel direction plate material. Radiation detector.
6. A semiconductor layer that generates a charge upon receiving photons of radiation, a common electrode that is formed on one surface of the semiconductor layer and applies a bias voltage to the semiconductor layer, and a pixel electrode that is formed on the other surface of the semiconductor layer A plurality of detection element modules in which detection elements having a two-dimensional array are arranged;
   A scattered radiation removing member disposed on the surface of the detection element;
   Wiring for connecting the scattered radiation removing member and the common electrode,
   A radiation detector that feeds power to the common electrode through the scattered radiation removing member and the wiring.
7. A semiconductor layer that generates a charge upon receiving photons of radiation, a common electrode that is formed on one surface of the semiconductor layer and applies a bias voltage to the semiconductor layer, and a pixel electrode that is formed on the other surface of the semiconductor layer A plurality of detection element modules in which detection elements having a two-dimensional array are arranged;
   A power supply lead wiring portion disposed on the surface of the common electrode of each detection element included in the detection element module,
   A radiation detector in which the lead wiring portion is configured by arranging a plurality of strip-shaped plate-like wirings at predetermined intervals in the channel direction.
8. 8. The radiation detector according to claim 7, wherein each plate-like wiring of the lead wiring portion is a mesh, and the mesh pattern of the mesh is inclined with respect to the arrangement direction of the detection elements.
9. 8. The radiation detector according to claim 7, wherein each plate-like wiring of the lead wiring portion is a mesh, and the mesh pattern of the mesh is a lattice shape matching the arrangement direction of the detection elements.
10. 8. The radiation detector according to claim 7, wherein each conductive material of the lead wiring portion has a mesh shape in which lead wires having a wiring width smaller than a pixel pitch of the detection element are knitted.
11. 8. The radiation detector according to claim 7, wherein a conductor sheet made of a material having substantially the same X-ray attenuation characteristics as the conductive material is provided in a gap between the conductive materials in the lead wiring portion.
12. 8. The radiation detector according to claim 7, wherein a conductor layer covering the entire common electrode is provided on a surface of the lead wiring portion.
13. 8. The radiation detector according to claim 7, wherein the lead wiring portion and the common electrode are protected by different insulators.
14. A semiconductor layer that generates a charge upon receiving photons of radiation, a common electrode that is formed on one surface of the semiconductor layer and applies a bias voltage to the semiconductor layer, and a pixel electrode that is formed on the other surface of the semiconductor layer A plurality of detection element modules formed by two-dimensionally arranging a plurality of detection elements having
    A plurality of power supply leads arranged on the surface of the common electrode of each detection element included in the detection element module,
    A radiation detector in which a plurality of the lead wires are arranged at predetermined intervals on the surface of the common electrode.
15. 15. The radiation detector according to claim 14, wherein the plurality of lead wires are arranged to be inclined with respect to the arrangement direction of the detection elements.
16. 15. The radiation detector according to claim 14, wherein the plurality of lead wires are arranged in parallel to the arrangement direction of the detection elements.

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