JP3999470B2 - Radiation solid state detector, and radiation image recording / reading method and apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation solid state detector having a power storage unit that accumulates an amount of electric charge corresponding to the dose of irradiated radiation as a latent image charge, and records radiation image information as an electrostatic latent image using the detector. And a method and apparatus for reading a recorded electrostatic latent image.
[0002]
[Prior art]
Conventionally, in medical radiography and the like, a radiation solid state detector having a photoconductor such as a selenium plate that is sensitive to radiation such as X-rays in order to reduce exposure doses to the subject and improve diagnostic performance (static The electrophotographic recording medium) is used as a photoconductor, the detector is irradiated with X-rays, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated in a power storage unit in the detector, so that radiographic image information is statically stored. There is known a method of reading radiographic image information from the detector by scanning a detector on which radiographic image information is recorded with a laser beam or a line light source as well as recording as an electrostatic latent image (for example, US Pat. 4535468 etc.).
[0003]
In the method according to the above-mentioned US Pat. No. 4,535,468, an X-ray photoconductive layer, a charge storage layer (also referred to as an intermediate layer or a trap layer) for storing charges generated in the X-ray photoconductive layer, and a reading photoconductive layer are arranged in this order. A detector having a three-layer structure is used, and during recording, a high voltage is applied between electrodes provided on both sides of the three layers to irradiate X-rays to accumulate latent image charges in the charge storage layer. Then, the latent image charge is read out by short-circuiting the electrodes. In this method, the reading photoconductive layer of the detector is made thinner than the X-ray photoconductive layer, thereby increasing the reading speed and improving the responsiveness.
[0004]
[Problems to be solved by the invention]
However, the method according to the above-mentioned US Pat. No. 4,535,468 has a problem that the amount of signal charge detected outside is small because the reading photoconductive layer is made thinner than the X-ray photoconductive layer. Furthermore, the charge storage layer cannot be thick because both electrons and holes have low charge mobility. This is because when the film thickness is increased, the response becomes slow or an afterimage. On the other hand, when the film thickness is thin, the amount of charge that can be accumulated decreases. That is, it is difficult to achieve both high-speed read response and efficient signal charge extraction.
[0005]
On the other hand, the applicant of the present application disclosed in Japanese Patent Application Nos. 10-232824 and 10-271374 a radiation solid-state detector that makes it possible to achieve both high-speed read-out response and efficient signal charge extraction, and A recording apparatus for recording radiation image information on the detector and a reading method and apparatus for reading the radiation image information from the detector on which the radiation image information is recorded as an electrostatic latent image are proposed.
[0006]
In the method described in Japanese Patent Application No. 10-232824, a recording photoconductive layer which exhibits conductivity by receiving irradiation of recording radiation or light emitted by excitation of this radiation, latent image charge Has a charge transport layer that acts as a substantially insulator and acts as a conductor for transport charges having a polarity opposite to that of the latent image charge, and reading light that exhibits conductivity when irradiated with a reading electromagnetic wave. Using a radiation solid detector with conductive layers in this order, the recording photoconductive layer side of the detector is irradiated with recording radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is recorded. The radiation image information is recorded as an electrostatic latent image by accumulating it in a power storage unit formed substantially at the interface between the photoconductive layer and the charge transport layer, and the recorded electrostatic latent image is read to obtain the radiation image information. Is.
[0007]
The present invention, as in the detector proposed in the above-mentioned Japanese Patent Application No. 10-232824 and the recording device and reading device according to the present application, achieves both high-speed reading response and efficient signal charge extraction. And a radiation solid state detector capable of further improving its performance as compared with that described in Japanese Patent Application No. 10-232824, and a method and apparatus for recording radiation image information in the detector It is another object of the present invention to provide a method and an apparatus for reading out radiation image information from a detector in which the radiation image information is recorded.
[0008]
[Means for Solving the Problems]
The first radiation solid detector according to the present invention further improves the detector described in the above Japanese Patent Application Nos. 10-232824 and 10-271374, that is, the radiation image information is obtained by irradiation with radiation. In a radiation solid-state detector for recording as an electrostatic latent image, the first electrode layer having transparency to recording radiation or light emitted by excitation of radiation, recording radiation, or irradiation with the light A recording photoconductive layer exhibiting electrical conductivity, a power storage unit that accumulates an amount of electric charge corresponding to the amount of irradiated radiation as a latent image charge, and reading light that exhibits electrical conductivity when irradiated with an electromagnetic wave for reading A conductive layer and a second electrode layer that is irradiated with a reading electromagnetic wave are provided in this order, and the second electrode layer has a plurality of lines for generating photocharge pairs with respect to the irradiation of the reading electromagnetic wave. 1st str And a second stripe electrode composed of a large number of linear electrodes for generating no photocharge pairs with respect to the electromagnetic wave for reading, and the first stripe electrode and the second stripe electrode are alternately substantially parallel to each other. It is characterized by being arranged.
[0009]
The second radiation solid state detector according to the present invention is a radiation solid state detector that records radiation image information as an electrostatic latent image by irradiation of radiation, for recording radiation or light emitted by radiation excitation. A first electrode layer having transparency, a recording photoconductive layer that exhibits conductivity when irradiated with the recording radiation or the light, and an amount of charge corresponding to the dose of the irradiated radiation as a latent image charge A power storage unit that accumulates, a photoconductive layer for reading that exhibits conductivity when irradiated with electromagnetic waves for reading, and a second electrode layer that is irradiated with electromagnetic waves for reading are arranged in this order. The electrode layer has a first stripe electrode composed of a large number of linear electrodes that are transparent to irradiation of the electromagnetic wave for reading, and a second stripe electrode that has a light shielding property against the electromagnetic wave for reading, First strike A type electrode and the second stripe electrode is characterized in that formed by substantially parallel arranged alternately.
[0010]
Here, the “linear electrode” means an electrode having an elongated shape as a whole, and may be any columnar or prismatic one as long as it has an elongated shape. However, it is particularly preferable to use a flat plate electrode.
[0011]
In the radiation solid detector, the second stripe electrode may be coated with Al or Cr metal.
[0012]
Further, one pixel line of the radiation solid state detector can be composed of one first stripe electrode and a second stripe electrode adjacent to the one first stripe electrode.
[0013]
In addition, one pixel line of the radiation solid state detector can be composed of a plurality of first stripe electrodes and a second stripe electrode adjacent to each of the plurality of first stripe electrodes.
[0014]
The power storage unit includes a conductive member provided on each of the radiation solid state detectors extending on the first stripe electrode and the second stripe electrode, and a latent image accumulated by the conductive member. The charge can be held at the same potential.
[0015]
Here, “provided for each pixel” preferably means that each pixel has the same potential for the latent image charge and can move the charge around the pixel to the center of the pixel during reading. Means that a single conductive member is provided, and a large number of conductive members are randomly arranged for one pixel, and the charge in the pixel peripheral portion cannot be moved to the pixel central portion during reading. Not included.
[0016]
In addition, “each separately” means that each conductive member is arranged in a discrete state, that is, in a floating state in which it is not connected to other pixels. Note that in the case where a plurality of conductive members are provided for one pixel, it is preferable to electrically connect the members for one pixel.
[0017]
The size of the conductive member is preferably set to be approximately the same as the pixel pitch. Alternatively, the latent image charge may be concentrated at the center of the pixel by setting it to be smaller than the pixel pitch, for example, ½ or less and disposing it at the center of the pixel. The size of the conductive member is, for example, the diameter in the case of a circular conductive member, and the length of each side in the case of a rectangular conductive member. The shape of the conductive member may be any shape such as a circle or a rectangle.
[0018]
In addition, a charge transport layer that acts as a substantially insulator for latent image charges and a substantially conductor for charges having a polarity opposite to that of the latent image charges is provided with a recording photoconductive layer and a reading light. The power storage portion can be formed at the interface between the charge transport layer and the reading photoconductive layer.
[0019]
Further, a trap layer for capturing the latent image charge can be provided between the recording photoconductive layer and the reading photoconductive layer, and in the trap layer or the interface between the trap layer and the recording photoconductive layer. It can be assumed that a power storage unit is formed.
[0020]
Also, the width of the second stripe electrode can be wider than the width of the first stripe electrode.
[0021]
In the first radiographic image recording method according to the present invention, the radiation solid detector is irradiated with radiation, and an amount of charge corresponding to the dose of the irradiated radiation is stored in the power storage unit of the radiation solid detector as a latent image charge. In the radiographic image recording method of recording radiographic image information as an electrostatic latent image in the power storage unit by accumulating, the first stripe electrode and the second stripe electrode have substantially the same potential, and the first electrode layer and the first electrode layer Recording is performed by applying a DC voltage between the two electrode layers.
[0022]
In the second radiographic image recording method according to the present invention, the radiation solid detector is irradiated with radiation, and an amount of charge corresponding to the dose of the irradiated radiation is stored as a latent image charge in the power storage unit of the radiation solid detector. In the radiographic image recording method of recording radiographic image information as an electrostatic latent image in the power storage unit by accumulating, the second stripe electrode is opened and a direct current is applied between the first stripe electrode and the first electrode layer. Recording is performed by applying a voltage.
[0023]
According to a third radiographic image recording method of the present invention, the radiation solid detector is irradiated with radiation, and an amount of charge corresponding to the dose of the irradiated radiation is stored as a latent image charge in the power storage unit of the radiation solid detector. In a radiographic image recording method for recording radiographic image information as an electrostatic latent image in a power storage unit by accumulating, a DC voltage is applied between the first stripe electrode and the first electrode layer, and a DC voltage is applied. Thus, recording is performed by applying a control voltage for adjusting the electric field distribution formed between the first stripe electrode and the first electrode layer to the second stripe electrode.
[0024]
Here, in the first to third radiological image recording methods, the above-mentioned “irradiating the radiation solid detector with radiation” means recording radiation carrying the radiographic image information of the subject directly or indirectly to the detector. This is not limited to direct irradiation of the recording radiation directly to the detector. For example, recording of fluorescence emitted in the scintillator by irradiating the scintillator (phosphor) with radiation, etc. It also includes irradiating the detector with light emitted by excitation of the radiation.
[0025]
In the third radiographic image recording method, the “control voltage” is a voltage having a magnitude that the second stripe electrode has a predetermined influence on a latent image charge accumulation process at the time of recording, for example, When the second stripe electrode is not provided, the size can be set to be approximately the same as the electric field distribution to be formed.
[0026]
Further, the region where the latent image charges are formed can be changed by actively approaching, moving away from, or the same as the potential of the second electrode layer. As a result, the signal extraction efficiency and the signal read response speed can be improved.
[0027]
This control voltage may be a DC voltage or an AC voltage. The AC voltage is not limited to a sine wave voltage, and may be any waveform as long as it can improve the signal extraction efficiency and the signal readout response speed as described above.
[0028]
The radiographic image reading method according to the present invention is the radiographic image reading method of reading radiographic image information from the radiation solid detector, wherein the first stripe electrode and the second stripe electrode are set to substantially the same potential, and the electromagnetic wave for reading is generated in the first manner. By irradiating the second electrode layer, an electric signal having a level corresponding to the amount of latent image charge accumulated in the power storage unit is obtained.
[0029]
Here, the “reading electromagnetic wave” may be a continuous wave emitted continuously or a pulse wave emitted in a pulse shape, but the pulse wave generates a larger current. Since even a pixel with a low latent image charge amount can be detected as a sufficiently large current, the S / N of the image can be dramatically improved, which is advantageous. .
[0030]
Further, when using the detector provided with the “conductive member”, the latent image charge is accumulated by being concentrated on the conductive member, so that it corresponds to at least the position where the conductive member is provided. The reading photoconductive layer is preferably irradiated with a reading electromagnetic wave. In this reading, the conductive member may be left open.
[0031]
A radiographic image recording apparatus according to the present invention is an apparatus for realizing the first or third radiographic image recording method, and applies a DC voltage between the first electrode layer and the first stripe electrode. Application means and control voltage application means for applying to the second stripe electrode a control voltage for adjusting the electric field distribution formed between both electrode layers by the DC voltage applied by the voltage application means It is characterized by.
[0032]
A radiographic image recording apparatus according to the present invention is an apparatus for realizing the second radiographic image recording method, and includes a voltage applying unit that applies a DC voltage between the first electrode layer and the first stripe electrode. And switching means for opening the second stripe electrode in order to adjust the electric field distribution formed between the two electrode layers by the DC voltage applied by the voltage applying means.
[0033]
A radiographic image reading apparatus according to the present invention is an apparatus for realizing the radiographic image reading method, wherein the first stripe electrode and the second stripe electrode are set to substantially the same potential, and the read electromagnetic wave is supplied to the second electrode. It is characterized by comprising image signal acquisition means for obtaining an electric signal of a level corresponding to the amount of latent image charge accumulated in the power storage unit by irradiating the layer.
[0034]
In the radiographic image reading apparatus, the image signal acquisition unit may be connected to the first stripe electrode.
[0035]
【The invention's effect】
According to the radiation solid-state detector of the present invention, the second electrode layer includes the first stripe electrode composed of a large number of linear electrodes for generating photocharge pairs with respect to the irradiation of the reading electromagnetic wave, and the reading electromagnetic wave. In contrast, the first stripe electrode and the second stripe electrode are alternately arranged substantially in parallel with each other. In addition, a new capacitor can be formed between the power storage unit formed between the recording photoconductive layer and the reading photoconductive layer and the second stripe electrode, and the latent image accumulated in the power storage unit by recording can be formed. The transport charge having the opposite polarity to the image charge can be charged also to the second stripe electrode by the charge rearrangement at the time of reading, and the first stripe electrode of the second electrode layer via the photoconductive layer for reading Formed with power storage unit The amount of the transport charge distributed to the capacitor can be made relatively smaller than when the second stripe electrode is not provided, and the amount of signal charge that can be taken out from the detector is increased to increase the reading efficiency. It becomes possible to improve.
[0036]
According to the radiographic image reading method and apparatus according to the present invention, the signal charge representing the radiographic image information is read out from the detector according to the present invention in which the radiographic image information is recorded through the second stripe electrode and accumulated in the power storage unit. An electric signal having a level corresponding to the amount of latent image charge is obtained. Therefore, more charges can be read from the detector, so that the reading efficiency is increased, a larger signal can be obtained, and the S / N of the image can be improved.
[0037]
Further, even if the second stripe electrode is provided, the thickness of the recording photoconductive layer and the reading photoconductive layer is not substantially affected, so that the read response is not adversely affected. For example, as described in Japanese Patent Application Nos. 10-232824 and 10-271374, the total thickness of the charge transport layer and the reading photoconductive layer is made thinner than the thickness of the recording photoconductive layer. By doing so, the responsiveness at the time of reading can be improved. That is, according to the present invention, the reading efficiency can be further improved as compared with the case of using a conventional detector while maintaining high-speed response at the time of reading.
[0038]
According to the radiation image recording method and apparatus of the present invention, the control voltage for adjusting the electric field distribution formed between the first electrode layer and the second electrode layer is applied to the second stripe electrode. As a result, signal extraction efficiency and signal read response speed can be improved.
[0039]
In addition, if the conductive member that equalizes the latent image charge is a detector provided in the power storage unit for each pixel of the image represented by the electrical signal, each pixel accumulated on the conductive member It is possible to make all the latent image charges have the same potential, and the reading efficiency can be improved as compared with the case where there is no conductive member. This is because, since the potential of the latent image charge is kept constant within the range of the conductive member, the latent image charge in the pixel peripheral portion, which is generally difficult to read out, is adjusted according to the progress of reading as long as it is in the conductive member. This is because the latent image charge can be discharged more sufficiently.
[0040]
Further, the pixel can be formed at a fixed position where the conductive member is disposed, and the structure noise can be easily corrected.
[0041]
Furthermore, if the size of the conductive member is set smaller than the pixel pitch and arranged in the center of the pixel, the electric field distribution formed at the time of recording can be made into a distribution shape attracted to the conductive member. Can be concentrated and accumulated in the center of the pixel, and the sharpness of the image can be improved.
[0042]
In addition, when a conductive member is provided in a detector provided with a charge transport layer and a trap layer, the charge accumulation effect by each of these layers can be used. That is, when the size of the conductive member is set smaller than the pixel pitch, if these layers are not provided, the charges not captured by the conductive member cannot be accumulated as latent image charges, which is effective in improving the sharpness. However, it is possible to improve the sharpness without reducing the accumulated charge amount by accumulating the charge as a latent image charge by each layer.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0044]
FIG. 1 is a diagram showing a schematic configuration of a radiation solid-state detector according to a first embodiment of the present invention, FIG. 1 (A) is a perspective view, FIG. 1 (B) is an XZ cross-sectional view of a Q arrow portion, and FIG. 1 (C) is an XY cross-sectional view of the P arrow part. The detector 20 has a first electrode layer 21 having transparency to recording radiation (for example, X-rays, etc., hereinafter referred to as recording light) L1, and irradiation of the recording light L1 transmitted through the electrode layer 21. The recording photoconductive layer 22 which exhibits conductivity by receiving the light, acts as a substantially insulator for latent image charges (for example, negative charges), and transport charges having the opposite polarity to the latent image charges (described above) In the example, the charge transport layer 23 that acts as a substantially conductive material for the positive charge), the read photoconductive layer 24 that exhibits conductivity when irradiated with the read electromagnetic wave (hereinafter referred to as read light) L2, the read The second electrode layer 25 having transparency to the light L2 is laminated in this order, and the sub electrode 27 is provided in the electrode layer 25.
[0045]
The electrode of the electrode layer 25 is a stripe electrode 26 in which a large number of elements 26 a are arranged in a stripe shape, and further, the power storage unit 29, which is an interface between the recording photoconductive layer 22 and the charge transport layer 23, has a pixel pitch. And a microplate 28 of substantially the same size.
[0046]
The sub-electrode 27 provided in the electrode layer 25 has a large number of elements 27a arranged in a stripe pattern. In each element 27a, the elements 27a and the elements 26a of the stripe electrode 26 are alternately arranged. It is arranged so that. The space 25a between both elements is, for example, filled with a polymer material such as polyethylene in which a small amount of a pigment such as carbon black is dispersed, and has a light shielding property against the reading light L2. Further, the stripe electrode 26 and the sub electrode 27 are electrically insulated. The sub-electrode 27 is a conductive member for outputting an electric signal of a level corresponding to the amount of latent image charge accumulated in the power storage unit 29 formed at a substantially interface between the recording photoconductive layer 22 and the charge transport layer 23. It is.
[0047]
The sub-electrode 27 is coated with a metal such as AL or Cr and has a light-shielding property against the reading light L2, and a signal extraction is performed in the reading photoconductive layer 24 corresponding to the element 27a. So as not to generate charge pairs. The sub electrode 27 only needs to have conductivity, and can be made of a single metal such as gold, silver, chromium, or platinum, or an alloy such as indium oxide.
[0048]
If the voltage of the sub electrode 27 is controlled to be the same potential as that of the stripe electrode 26, the electric field distribution formed between the electrode layer 21 and the electrode layer 25 can be made uniform. Further, if the sub-electrode is opened or controlled so as to be closer to the potential of the electrode layer 21 than the potential of the stripe electrode 26, the latent image charge can be more concentrated and accumulated on the stripe electrode 26. Become.
[0049]
The microplate 28 extends not only directly above the element 26a but also directly above the element 27a. As a result, the latent image charges accumulated on the microplate 28 are always held at the same potential, and can be freely moved on the microplate 28 to facilitate discharge at the time of reading. . Note that the microplate 28 may be arranged so that the center of the microplate 28 is located directly above the element 27a so that charges around the pixels can be collected more easily.
[0050]
The microplate 28 is deposited on the dielectric layer using, for example, vacuum evaporation or chemical deposition, and is a single metal such as gold, silver, aluminum, copper, chromium, titanium, platinum, or an alloy such as indium oxide. Can be made from a thin film. The microplate 18 can be deposited as a continuous layer, which is then etched to form a plurality of individual discrete microplates having dimensions in the same range as the smallest resolvable pixel. . These discrete microplates can also be made using optical micromachining techniques such as laser application or photoetching (see “Imaging for Microfabrication” (JMShaw, IBM Watson Research Center) in “Imaging Procesing & Materials” Chapter 18).
[0051]
Examples of the material of the recording photoconductive layer 22 include amorphous selenium (a-Se), PbO, and PbI. ₂ Lead oxide (II), lead iodide (II), Bi ₁₂ (Ge, Si) O ₂₀ , Bi ₂ I ₃ / A photoconductive substance containing at least one of organic polymer nanocomposites as a main component is suitable.
[0052]
As the substance of the charge transport layer 23, for example, the larger the difference between the mobility of the negative charge charged in the electrode layer 21 and the mobility of the positive charge having the opposite polarity, the better (for example, 10 ² Or more, preferably 10 ³ Above) Poly N-vinylcarbazole (PVK), N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD), An organic compound such as a discotic liquid crystal, a TPD polymer (polycarbonate, polystyrene, PUK) dispersion, or a semiconductor material such as a-Se doped with 10 to 200 ppm of Cl is suitable. In particular, organic compounds (PVK, TPD, discotic liquid crystal, etc.) are preferable because they have light insensitivity, and since the dielectric constant is generally small, the capacitance of the charge transport layer 23 and the reading photoconductive layer 24 is reduced, so that reading is possible. The signal extraction efficiency can be increased. Note that “having light insensitivity” means that even when irradiated with the recording light L1 and the reading light L2, it hardly exhibits conductivity.
[0053]
Examples of the material of the reading photoconductive layer 24 include a-Se, Se-Te, Se-As-Te, metal-free phthalocyanine, metal phthalocyanine, MgPc (Magnesium phtalocyanine), VoPc (phase II of Vanadyl phthalocyanine), and CuPc (Cupper phtalocyanine). ) And the like, and a photoconductive substance mainly containing at least one of them is preferred.
[0054]
The thickness of the recording photoconductive layer 12 is preferably not less than 50 μm and not more than 1000 μm so that the recording light L 1 can be sufficiently absorbed. In this example, the thickness is about 5500 μm. The total thickness of the charge transport layer 23 and the photoconductive layer 24 is preferably less than or equal to ½ of the thickness of the recording photoconductive layer 22, and the thinner the thickness, the better the response during reading. Therefore, for example, it is preferably 1/10 or less, more preferably 1/20 or less.
[0055]
As the electrode layer 21, for example, a nesa film obtained by applying a conductive substance on a transparent glass plate is suitable.
[0056]
In the detector 20, a capacitor C is connected between the power storage unit 29 and the sub electrode 27 via the reading photoconductive layer 24 and the charge transport layer 23. _{* C} Is formed. Even when the sub-electrode 27 is provided, the capacitor C formed between the electrode layer 21 and the power storage unit 29 via the recording photoconductive layer 22. _{* C} Capacity C _a , And the capacitor C formed between the stripe electrode 26 and the power storage unit 29 via the read photoconductive layer 24 and the charge transport layer 23. _{* B} Capacity C _c Does not have a substantial impact.
[0057]
Where capacitor C _{* B} , C _{* C} Thinking about the capacity of the capacity ratio C _{* B} : C _{* C} Is the ratio W of the width of each element 26a, 27a _b : W _c It becomes. This allows the capacitor C to be used during charge rearrangement. _{* B} Amount Q of positive charge distributed to _{+ B} Can be made relatively smaller than when the sub electrode 27 is not provided, and the current flowing out of the detector 20 to the outside can be made relatively larger than when the sub electrode 27 is not provided.
[0058]
In this detector 20, at least the capacitor C _{* B} , C _{* C} Is defined by the width ratio of the elements 26a and 27a forming the electrodes, so that the detector structure is simple and easy to manufacture.
[0059]
FIG. 2 is a diagram showing a schematic configuration of a radiation solid state detector according to a second embodiment of the present invention, FIG. 2 (A) is a perspective view, FIG. 2 (B) is an XZ cross-sectional view of a Q arrow portion, FIG. 2C is an XY cross-sectional view of the P arrow portion. In FIG. 2, elements that are the same as those of the detector 20 according to the second embodiment shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted unless particularly necessary. The detector 20a according to the second embodiment removes the microplate 28 of the detector 20, connects the stripe electrode 26 and the sub electrode 27 during recording, and actively uses the sub electrode 27 to form an electric field distribution. It is intended to be used.
[0060]
FIG. 3A is a charge model showing an electrostatic latent image recording process in the case where recording is performed by connecting the stripe electrode 26 and the sub-electrode 27, and FIG. 3B shows the transmissive portion 9a of the subject. Is a charge model showing an electrostatic latent image reading process. When recording is performed by connecting the stripe electrode 26 and the sub-electrode 27, the latent image charge is accumulated not only at the position corresponding to the element 26a but also at the position corresponding to the element 27a. At the time of reading, when the photoconductive layer 24 is irradiated with the reading light L2, the latent image charges of the portions corresponding to the two elements 27a, that is, the sky portions of the two elements 27a, are sequentially read out through the two elements 27a. It is. That is, as shown in FIG. 3B, a discharge is generated from the element 26a located at the center of the pixel toward the latent image charge (in the sky) corresponding to the adjacent element 27a, thereby reading out. proceed. In order to extract more signal charges, it is better to make the width of the element 27a wider than the width of the element 26a.
[0061]
FIG. 4 is a diagram showing a schematic configuration of a radiation solid state detector according to a third embodiment of the present invention, FIG. 4 (A) is a perspective view, FIG. 4 (B) is an XZ cross-sectional view of a Q arrow portion, FIG. 4C is an XY cross-sectional view of the P arrow part. In FIG. 4 as well, elements that are the same as those of the detector 20 according to the first embodiment shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted unless particularly necessary. The detector 20b according to the third embodiment removes the microplate 28 of the detector 20, and alternately provides both the element 26a of the stripe electrode 26 and the element 27a of the sub-electrode 27 in one pixel. It is the thing of the composition. In the illustrated detector 20a, three elements 26a and 27a are provided in one pixel. When recording and reading are performed using the detector 20b, the elements 26a and 27a may be handled together in units of one pixel. If the size of one pixel of the detectors 20 and 20b is the same, the width W of each element 26a and 27a of the detector 20b. _b ', W _c 'Is the width W of the detector 20 _b , W _c It is set narrower than. In today's advanced semiconductor formation technology, it is easy to form both elements 26a and 27a sufficiently narrow, and the detector 20b can be easily manufactured.
[0062]
In this case, the ratio D1 / D2 of the distance D1 between the power storage unit 29 and the electrode layer 25 and the distance D2 between the elements 26a and 27a is compared with the detector 20a according to the second embodiment. Easy to enlarge. This facilitates discharge from the element 26a toward the latent image charges corresponding to the elements 27a on both sides thereof, and the reading time can be made shorter than that of the detector 20a. This is particularly effective when the microplate 28 is not provided.
[0063]
FIG. 5 is a diagram showing a schematic configuration of a radiation solid state detector according to a fourth exemplary embodiment of the present invention, FIG. 5 (A) is a perspective view, FIG. 5 (B) is an XZ cross-sectional view of a Q arrow portion, FIG. 5C is an XY cross-sectional view of the P arrow part. In FIG. 5 as well, elements that are the same as those of the detector 20 according to the first embodiment shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted unless particularly necessary. The detector 20c according to the fourth embodiment has a configuration in which the charge transport layer 23 of the detector 20a is removed.
[0064]
A detailed description of the operation in the recording process and the reading process when using the detector 20c is omitted, but in the recording process, negative charges generated in the recording photoconductive layer 23 are accumulated on the microplate 28. Also, in the reading process, the latent image charge can be discharged more sufficiently, resulting in less unread.
[0065]
Furthermore, in any of the detectors according to the above-described embodiments, the recording photoconductive layer exhibits conductivity when irradiated with recording radiation. However, the recording photoconductive layer of the detector according to the present invention is However, the present invention is not necessarily limited thereto, and the recording photoconductive layer may exhibit conductivity by irradiation with light emitted by excitation of recording radiation (see Japanese Patent Application No. 10-232824). In this case, a wavelength conversion layer called a so-called X-ray scintillator that converts the wavelength of recording radiation into light of another wavelength region such as blue light is laminated on the surface of the first electrode layer. As this wavelength conversion layer, for example, cesium iodide (CsI) or the like is preferably used. In addition, the first electrode layer is transmissive to light emitted from the wavelength conversion layer by excitation of recording radiation.
[0066]
In the detectors 20, 20a, 20b, a charge transport layer is provided between the recording photoconductive layer and the reading photoconductive layer, and a power storage unit is formed at the interface between the recording photoconductive layer and the charge transport layer. However, in the present invention, the charge transport layer may be replaced with a trap layer. In the case of the trap layer, the latent image charge is trapped in the trap layer, and the latent image charge is accumulated in the trap layer or at the interface between the trap layer and the recording photoconductive layer. Further, a microplate may be specially provided for each pixel at the interface between the trap layer and the recording photoconductive layer.
[0067]
In the detector according to the above-described embodiment, one square microplate is provided for each pixel. However, the pixel is formed at a fixed position, or the latent image charge is set to the same potential. As long as the latent image charge at the periphery of the pixel can be sufficiently discharged during the reading process, or the latent image charge can be concentrated at the center of the pixel during the recording process, the number is somewhat larger. It doesn't matter. For example, four conductive members each having a triangular shape are arranged in a square shape for each pixel as a whole, and in the recording process or the reading process, the apex of the triangular member in the central part of the square is opposed to the opposite part. For example, the latent image charges are collected, and the fan-shaped conductive member is arranged in a circular shape as a whole.
[Brief description of the drawings]
FIG. 1 is a perspective view (A) of a radiation solid detector according to a first embodiment of the present invention, an XZ sectional view (B) of a Q arrow portion, and an XY sectional view (C) of a P arrow portion.
2A is a perspective view of a radiation solid state detector according to a second embodiment of the present invention, FIG. 2B is an XZ sectional view of a Q arrow portion, and FIG. 2C is an XY sectional view of a P arrow portion.
FIG. 3 shows a charge model (A) showing an electrostatic latent image recording process and a charge model (B) showing an electrostatic latent image reading process in the case of using the radiation solid state detector according to the second embodiment.
4A is a perspective view of a radiation solid state detector according to a third embodiment of the present invention, FIG. 4B is an XZ sectional view of a Q arrow portion, and FIG. 4C is an XY sectional view of a P arrow portion.
5A is a perspective view of a radiation solid state detector according to a fourth embodiment of the present invention, FIG. 5B is an XZ sectional view of a Q arrow portion, and FIG. 5C is an XY sectional view of a P arrow portion.
[Explanation of symbols]
20 Radiation solid state detector
21 First electrode layer
22 Photoconductive layer for recording
23 Charge transport layer
24 Photoconductive layer for reading
25 Second electrode layer
26 Striped electrode
27 Sub-electrode (first conductive member)
28 Microplate (second conductive member)
29 Power storage unit
71 Image signal acquisition means
72 Power supply (functions as voltage application means and control voltage application means)
L1 radiation for recording (recording light)
L2 Electromagnetic wave for reading (reading light)

Claims (17)

In a radiation solid state detector that records radiation image information as an electrostatic latent image by irradiation of radiation,
A first electrode layer that is transmissive to recording radiation or light emitted by excitation of the radiation;
A photoconductive layer for recording that exhibits conductivity by being irradiated with the recording radiation or the light;
A power storage unit that accumulates a charge corresponding to a dose of the irradiated radiation as a latent image charge,
A photoconductive layer for reading which exhibits conductivity by receiving irradiation of electromagnetic waves for reading;
The second electrode layer irradiated with the electromagnetic wave for reading is provided in this order,
The second electrode layer includes a first stripe electrode composed of a plurality of linear electrodes for generating photocharge pairs with respect to irradiation of the read electromagnetic wave, and no photocharge pairs with respect to the read electromagnetic wave. And a second stripe electrode comprising a plurality of linear electrodes, wherein the first stripe electrode and the second stripe electrode are alternately arranged substantially in parallel. In a radiation solid state detector that records radiation image information as an electrostatic latent image by irradiation of radiation,
A first electrode layer that is transmissive to recording radiation or light emitted by excitation of the radiation;
A recording photoconductive layer that exhibits conductivity by being irradiated with the recording radiation or the light, a power storage unit that accumulates an amount of charge corresponding to a dose of the irradiated radiation as a latent image charge,
A photoconductive layer for reading which exhibits conductivity by receiving irradiation of electromagnetic waves for reading;
The second electrode layer irradiated with the electromagnetic wave for reading is provided in this order,
The second electrode layer has a first stripe electrode composed of a large number of linear electrodes that are transparent to irradiation of the read electromagnetic wave, and a second stripe that has a light blocking property to the read electromagnetic wave. A solid state radiation detector comprising: an electrode, wherein the first stripe electrode and the second stripe electrode are alternately arranged substantially in parallel.   3. The radiation solid state detector according to claim 1, wherein the second stripe electrode is coated with a metal of Al or Cr.   2. A pixel line of the radiation solid state detector is composed of one first stripe electrode and the second stripe electrode adjacent to the first stripe electrode. The radiation solid state detector according to any one of 3 to 3.   2. A pixel line of the radiation solid state detector is constituted by a plurality of the first stripe electrodes and the second stripe electrodes adjacent to each of the plurality of first stripe electrodes. The radiation solid state detector according to any one of 3 to 3.   The power storage unit includes conductive members provided on the first stripe electrode and the second stripe electrode and provided separately for each pixel of the radiation solid state detector, and the accumulation is performed by the conductive member. 6. The radiation solid state detector according to claim 1, wherein the latent image charges are held at the same potential. For the latent image charges act as insulation material, and a charge transport layer which acts as a conductor with respect to charges of the latent image charges opposite polarity, the reading and the recording photoconductive layer Between the photoconductive layer for
The radiation solid-state detector according to claim 1, wherein the power storage unit is formed at an interface between the charge transport layer and the recording photoconductive layer. A trap layer for capturing the latent image charge, between the recording photoconductive layer and the reading photoconductive layer;
7. The radiation solid state detector according to claim 1, wherein the power storage unit is formed in the trap layer or at an interface between the trap layer and the recording photoconductive layer.   The radiation solid-state detector according to any one of claims 1 to 8, wherein the width of the second stripe electrode is wider than the width of the first stripe electrode. The radiation solid-state detector according to claim 1 is irradiated with radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated as a latent image charge in the power storage unit of the radiation solid-state detector. Thus, in a radiographic image recording method for recording radiographic image information as an electrostatic latent image in the power storage unit,
The first stripe electrode and the second stripe electrode are set to substantially the same potential, and the recording is performed by applying a DC voltage between the first electrode layer and the second electrode layer. A radiographic image recording method. The radiation solid-state detector according to claim 1 is irradiated with radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated as a latent image charge in the power storage unit of the radiation solid-state detector. Thus, in a radiographic image recording method for recording radiographic image information as an electrostatic latent image in the power storage unit,
A radiographic image recording method, wherein the recording is performed by making the second stripe electrode open and applying a DC voltage between the first stripe electrode and the first electrode layer. The radiation solid-state detector according to claim 1 is irradiated with radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated as a latent image charge in the power storage unit of the radiation solid-state detector. Thus, in a radiographic image recording method for recording radiographic image information as an electrostatic latent image in the power storage unit,
A DC voltage is applied between the first stripe electrode and the first electrode layer, and an electric field distribution is formed between the first stripe electrode and the first electrode layer by applying the DC voltage. A radiographic image recording method, wherein the recording is performed by applying a control voltage for adjusting the second stripe electrode to the second stripe electrode.   The radiation image reading method for reading the radiation image information from the radiation solid state detector according to claim 1, wherein the radiation image information is recorded as an electrostatic latent image, wherein the first stripe electrode and the second stripe are read. An electric signal having a level corresponding to the amount of latent image charge accumulated in the power storage unit is obtained by causing the electrodes to have substantially the same potential and irradiating the second electrode layer with the reading electromagnetic wave. A radiation image reading method. The radiation solid-state detector according to claim 1 is irradiated with radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated as a latent image charge in the power storage unit of the radiation solid-state detector. In the radiographic image recording apparatus for recording radiographic image information as an electrostatic latent image in the power storage unit,
Voltage applying means for applying a DC voltage between the first electrode layer and the first stripe electrode;
Radiation comprising: control voltage applying means for applying a control voltage for adjusting the electric field distribution formed between the two electrode layers by the DC voltage applied by the voltage applying means to the second stripe electrode. Image recording device. The radiation solid-state detector according to claim 1 is irradiated with radiation, and an amount of electric charge corresponding to the dose of the irradiated radiation is accumulated as a latent image charge in the power storage unit of the radiation solid-state detector. In the radiographic image recording apparatus for recording radiographic image information as an electrostatic latent image in the power storage unit,
Voltage applying means for applying a DC voltage between the first electrode layer and the first stripe electrode;
A radiographic image recording apparatus comprising: switching means for opening the second stripe electrode in order to adjust an electric field distribution formed between both electrode layers by a DC voltage applied by the voltage applying means. In the radiographic image reader which reads the radiographic image information from the radiation solid detector according to any one of claims 1 to 9, wherein the radiographic image information is recorded as an electrostatic latent image.
By causing the first stripe electrode and the second stripe electrode to have substantially the same potential, and irradiating the second electrode layer with the read electromagnetic wave, the amount of latent image charge accumulated in the power storage unit is increased. A radiographic image reading apparatus comprising image signal acquisition means for obtaining an electric signal of a corresponding level.   The radiographic image reading apparatus according to claim 16, wherein the image signal acquisition unit is connected to a first stripe electrode.

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