JP2008079727A - Radiation image information imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely position a grid relative to a radiation detection section in a simple constitution. <P>SOLUTION: A solid-state detector 36 is formed with a plurality of first marks 44, and the grid 38 is similarly formed with a plurality of second marks 46. The position of the grid 38 is adjustable in an arrow C direction and an arrow D direction in parallel to the surface 36a via an adjustment mechanism 48. The position of the grid 38 is so adjusted as to accord the first marks 44 with the second marks 46 under the operation of the adjustment mechanism 48. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiographic image information photographing apparatus that converts a radiographic image of a subject into an electric signal and reads the electric signal.

  In a radiographic image information imaging apparatus, for example, an X-ray mammography apparatus (mammography apparatus), a radiographic image of a subject (mammo) is recorded by irradiation of radiation, and information corresponding to the radiographic image is emitted by scanning of reading light. The radiation image information is read by relatively moving a reading light source unit that irradiates the reading light with respect to a radiation image recording unit (radiation detection unit).

  As a radiation image recording unit, a light solid state detector or the like of a light conversion method or a direct conversion method is used in addition to a method in which a plurality of photoelectric conversion elements and thin film transistors (TFTs) are arranged or a light readout method.

  Usually, in a radiographic image information imaging device, a scattered radiation removing grid is used in order to avoid the influence of fogging caused by scattered radiation. Here, particularly when using an X-ray detection means and a grid made of semiconductor pixels, it is necessary to accurately position the X-ray detection means and the grid in order to obtain a good image efficiently.

  Therefore, for example, an X-ray imaging apparatus disclosed in Patent Document 1 includes a housing 1 as shown in FIG. A groove portion 2 is provided on the side surface of the housing 1 in order to restrict the position of a grid unit (not shown), and the convex portion of the grid unit is fitted into the groove portion 2. For this reason, the rotation position of the grid unit around the axis perpendicular to the detection surface of the X-ray image detection panel 3 is restricted with respect to the housing 1.

  A protrusion 4 is provided at a corner of the inner wall of the housing 1, and a corner 6 of a substrate 5 on which the X-ray image detection panel 3 is mounted is engaged with the protrusion 4. Therefore, the rotation position of the substrate 5 around the axis perpendicular to the detection surface of the X-ray image detection panel 3 is restricted with respect to the housing 1.

JP 2002-156457 A (FIG. 2)

  However, in Patent Document 1 described above, in order to restrict the position of the grid with respect to the housing 1, the groove portion 2 and the convex portion are provided, and the position of the X-ray image detection panel 3 is restricted to the housing 1. In addition, a protrusion 4 that engages with the corner 6 is provided, and the engagement relationship must be set with high accuracy. This is because it is necessary to accurately position the grid and the X-ray image detection panel 3 with respect to the housing 1. For this reason, there exists a problem that the manufacturing cost of the whole X-ray imaging device rises considerably.

  In addition, the groove portion 2 is provided on the side surface of the housing 1, and the protrusion 4 is provided on the corner of the inner wall of the housing 1. Therefore, there is a problem that the degree of freedom in design of the entire X-ray imaging apparatus is lowered and the versatility is poor.

  The present invention solves this type of problem, and an object thereof is to provide a radiographic image information imaging apparatus capable of positioning a grid with high accuracy with respect to a radiation detection unit with a simple configuration. .

  The present invention relates to a radiographic image information imaging apparatus that converts a radiographic image of a subject into an electric signal and reads the electric signal. The radiographic image information imaging apparatus detects radiographic image information of a subject, is disposed nearer to the subject side than the radiation detection unit, a radiation detection unit provided with a first mark, and a second mark And an adjustment mechanism capable of adjusting the position of the radiation detection unit or the fixed type grid along the detection surface of the radiation detection unit so that the first mark and the second mark coincide with each other And.

  The adjustment mechanism preferably includes an actuator capable of adjusting the position of the radiation detection unit or the fixed grid in two axial directions parallel to the detection surface.

  Furthermore, it is preferable to provide a control unit that controls the adjustment mechanism based on the radiation image information of the first mark and the second mark obtained from the radiation detection unit.

  In the present invention, when radiation is irradiated on the radiation detection unit, the first mark provided on the radiation detection unit and the second mark provided on the fixed grid are photographed. Then, by reading the first mark and the second mark, the positions of the first mark and the second mark are detected. Next, the adjustment mechanism is driven, and the position of the radiation detection unit or the fixed grid is adjusted along the detection surface, whereby the first mark and the second mark coincide with each other.

  Therefore, the fixed grid can be positioned with high accuracy with respect to the radiation detection unit with a simple configuration. In addition, it is not necessary to position the fixed grid and the radiation detection unit with the positioning structure having the concavo-convex part, so that an increase in manufacturing cost can be prevented and versatility can be easily improved.

  FIG. 1 is an explanatory perspective view of a mammography apparatus 10 which is a radiographic image information imaging apparatus according to the first embodiment of the present invention.

  The mammography apparatus 10 irradiates a subject 22 with radiation, a base 16 installed in an upright state, an arm member 20 fixed to a turning shaft 18 disposed at a substantially central portion of the base 16, and a subject 22. A radiation source storage unit 24 that stores a radiation source (not shown) that is fixed to one end of the arm member 20, and a solid state detector that detects radiation transmitted through the subject 22 and acquires radiation image information An imaging table 26 that houses (described later) and is fixed to the other end of the arm member 20 and a pressing plate 28 that presses and holds the imaging region of the subject 22 against the imaging table 26. .

  The arm member 20 to which the radiation source storage unit 24 and the imaging stand 26 are fixed is configured to be adjustable in the imaging direction with respect to the imaging region of the subject 22 by rotating in the direction of arrow A about the rotation axis 18. The pressing plate 28 is disposed between the radiation source storage unit 24 and the imaging table 26 in a state of being connected to the arm member 20 and is configured to be displaceable in the arrow B direction.

  The base 16 displays photographing information of the subject 22 detected by the mammography apparatus 10, photographing information such as a photographing direction, ID information of the subject 22, and the like. An operation unit 30 is provided.

  FIG. 2 is an internal configuration diagram of the imaging stand 26 in the mammography apparatus 10, and shows a state in which a mammo 34 that is an imaging region of the subject 22 is set between the imaging stand 26 and the pressing plate 28.

  A solid-state detector (radiation) that accumulates radiation image information based on the radiation X output from the radiation source built in the radiation source storage unit 24 and outputs it as an electrical signal inside the housing 26a constituting the imaging table 26. Detection unit) 36, a fixed grid 38 disposed closer to the mammo 34 than the solid state detector 36, and the direction of the arrow C in order to read the radiation image information accumulated and recorded in the solid state detector 36 In order to remove unnecessary charges accumulated in the solid state detector 36, the solid state detector 36 is irradiated with erasing light. An erasing light source unit 42 is provided.

  The solid state detector 36 is a direct conversion type and optical readout type radiation solid state detector (conversion unit), which accumulates radiation image information including radiation X transmitted through the mammo 34 as an electrostatic latent image, and a reading light source unit. By scanning with the reading light from 40, a current corresponding to the electrostatic latent image is generated.

  Specifically, the solid state detector 36 is formed on a glass substrate, transmits a first conductive layer that transmits radiation X, a recording photoconductive layer that generates charges when irradiated with the radiation X, and the first detector. A charge transport layer acting as a substantially conductive material for a transport polarity charge opposite to the latent image polarity charge, while acting as a substantially insulator for the latent image polarity charge charged in one conductive layer; The photoconductive layer for reading which produces | generates an electric charge by being irradiated and exhibits electroconductivity, and the 2nd conductive layer which permeate | transmits the radiation X are laminated | stacked in order. A power storage unit is formed at the interface between the recording photoconductive layer and the charge transport layer.

  The first conductive layer and the second conductive layer each constitute an electrode. The electrode of the first conductive layer is a two-dimensional flat plate electrode, and the electrode of the second conductive layer is a plurality of lines having a predetermined pixel pitch for detecting recorded radiographic image information as an image signal. Configured as an electrode. The arrangement direction of the linear electrodes corresponds to the main scanning direction, and the extending direction of the linear electrodes corresponds to the sub-scanning direction (arrow C direction).

  As shown in FIG. 3, on the surface (detection surface) 36a of the solid state detector 36, for example, first marks 44 are provided in the vicinity of four corners outside the normal mammography region. The first mark 44 is formed of a radiation shielding material such as lead, for example. The first mark 44 can be set in various shapes.

  The grid 38 is formed by alternately laminating a plurality of foils made of lead or the like having a large X-ray absorption rate as an X-ray absorption member and an intermediate material made of aluminum or the like having a low X-ray absorption rate, for example, aluminum. Covered by a cover member made of

  A plurality of second marks 46 made of, for example, lead are provided on the surface 38a of the grid 38. The second mark 46 corresponds to the first mark 44 of the solid state detector 36, and at the position where the second mark 46 and the first mark 44 coincide, the grid 38 and the solid state detector 36 are Positioning is performed with a desired relative positional relationship.

  The position of the grid 38 can be adjusted in two axial directions (arrow C direction and arrow D direction) parallel to the surface 36a of the solid state detector 36 via the adjustment mechanism 48. The adjustment mechanism 48 constitutes a so-called XY table, and includes an actuator, for example, a first motor 50. A frame 54 is attached to an arrow C on the first drive screw shaft 52 attached to the first motor 50. It is connected to be able to move forward and backward.

  The frame body 54 is guided in the direction of arrow C via a pair of guide rails 56, and a large-diameter opening 58 is formed in the frame body 54. A grid 38 is placed in the opening 58 and the grid 38 is supported by a guide rail 60 extending in the direction of arrow D. An actuator, for example, a second motor 62 is fixed on the frame 54, and the grid 38 is connected to the second drive screw shaft 64 connected to the second motor 62 so as to be able to advance and retract in the direction of arrow D. .

  As shown in FIG. 2, the reading light source unit 40 irradiates, for example, a line light source configured by arranging a plurality of LED chips in a line and reading light output from the line light source on the solid detector 36 in a linear manner. And an optical system. By moving a line light source in which LED chips are arranged in a direction orthogonal to the extending direction of the linear electrodes constituting the second conductive layer of the solid state detector 36 in the extending direction of the linear electrodes, the solid state The entire surface of the detector is exposed and scanned.

  The erasing light source unit 42 is preferably a light source that emits and extinguishes light in a short time and has a very small afterglow. In addition, a plurality of external electrode type rare gas fluorescent lamps arranged in the arrangement direction can be used.

  FIG. 4 is a block diagram of a control circuit housed in the imaging stand 26 that constitutes the mammography apparatus 10.

  The mammography apparatus 10 includes a solid state detector 36, a power supply unit 70 that supplies a high voltage to the solid state detector 36, and supplies power to the adjustment mechanism 48, and each linear shape of the solid state detector 36 that is supplied with the high voltage. An amplifier 72 that amplifies the analog electrical signal output from the electrode, an A / D converter 74 that converts the amplified analog electrical signal into a digital electrical signal, and a substrate (control unit) that performs signal processing of the digital electrical signal 76.

  The operation of the mammography apparatus 10 configured as described above will be described below.

  First, using a console, an ID card, etc. (not shown), ID information related to the subject 22, a photographing method, and the like are set. In this case, the ID information includes information such as the name, age, and sex of the subject 22. Further, the imaging method includes information such as an imaging region and an imaging direction instructed by a doctor, and an engineer can input from the console. These pieces of information can be displayed and confirmed on the display operation unit 30 of the mammography apparatus 10.

  Next, the engineer sets the mammography apparatus 10 to a predetermined state according to the designated imaging method. For example, as a method of photographing the mammo 34, head-to-tail direction (CC) photographing (refer to FIG. 2) in which radiation X is irradiated from above, and side direction (ML) in which radiation X is irradiated from the side is photographed. There is imaging, inside / outside oblique (MLO) imaging in which radiation X is applied from an oblique direction, and the arm member 20 is pivoted about the pivot axis 18 in accordance with these imaging methods.

  Next, the subject 22 is set to the designated photographing state with respect to the mammography apparatus 10. For example, when performing head-to-tail (CC) imaging of the subject 22 with respect to the left mammo 34, as shown in FIG. A mammo 34 is held between the pressure plate 26 and the pressing plate 28.

  Therefore, the radiation source stored in the radiation source storage unit 24 is driven to capture radiographic image information. The radiation X transmitted through the mammo 34 held between the pressing plate 28 and the imaging stand 26 passes through the grid 38 stored in the imaging stand 26 and is irradiated to the solid state detector 36. Prior to photographing, the solid detector 36 is irradiated with erasing light from the erasing light source unit 42 to remove unnecessary charges.

  Next, in a state where a high voltage is applied between the first conductive layer and the second conductive layer from the power supply unit 70, when the radiation X carrying the radiation image information is irradiated onto the solid detector 36, the recording of the solid detector 36 is performed. Positive and negative charge pairs are generated in the photoconductive layer for use, and the negative charges are accumulated in a power storage unit formed at the interface between the recording photoconductive layer and the charge transport layer. The amount of the accumulated negative charge, that is, the latent image polarity charge, is approximately proportional to the dose of the radiation X transmitted through the mammo 34. The positive charge generated in the recording photoconductive layer is attracted to the first conductive layer and is combined with the negative charge supplied from the high voltage supply unit and disappears.

  After the radiographic image information is captured, the reading light source unit 40 emits reading light toward the solid state detector 36 while moving in the arrow C direction. For this reason, a positive and negative charge pair is generated in the reading photoconductive layer, and the positive charge is attracted to the negative charge (latent image polar charge) accumulated in the power storage unit, and moves in the charge transport layer. Combined with the negative charge of the power storage unit, it disappears. On the other hand, the negative charge generated in the reading photoconductive layer is combined with the positive charge supplied from the power supply unit 70 to the second conductive layer and disappears.

  In this way, the negative charge accumulated in the solid detector 36 is extinguished by charge coupling, and a current is generated in the solid detector 36 due to the movement of the charge during the charge coupling. The minute charges generated in the plurality of linear electrodes constituting the second conductive layer are amplified by each amplifier 72. The amplified analog electric signal is sent to the A / D converter 74 and converted into a digital electric signal, and then sent to various substrates 76 to perform desired signal processing, so that the radiation image information of the mammo 34 is obtained. can get.

  In this case, in the first embodiment, for example, when the mammography apparatus 10 is installed or when the grid 38 is attached to the inside of the casing 26a of the imaging table 26, the relative relationship between the grid 38 and the solid state detector 36 is obtained. Positioning work is performed.

  Specifically, in a state where the subject 22 does not exist, the radiation source is driven to irradiate the imaging table 26 with radiation. At this time, the grid 38 is provided with a plurality of, for example, four second marks 46 formed of lead or the like, and radiation image information relating to the second marks 46 is irradiated to the solid state detector 36.

  On the other hand, the solid detector 36 is provided with a plurality of, for example, four first marks 44 which are similarly formed of lead or the like. Therefore, when the reading light source unit 40 irradiates the solid detector 36 with reading light, radiation image information of the first mark 44 and the second mark 46 is obtained on the substrate 76 that is a control unit.

  Here, for example, as shown in FIG. 5, when the first mark 44 and the second mark 46 are displaced in the directions of the arrow C and the arrow D, the radiation image read from the solid state detector 36 as described above. Also in the information, it is detected that the first mark 44 and the second mark 46 are misaligned. Accordingly, power is supplied from the power supply unit 70 to the adjustment mechanism 48, and the first motor 50 and the second motor 62 are driven and controlled.

  As shown in FIG. 3, when the first drive screw shaft 52 rotates in a predetermined direction under the drive action of the first motor 50, the frame body 54 that engages with the first drive screw shaft 52 is formed on the guide rail 56. It moves in the direction of arrow C under the guidance action. For this reason, the grid 38 on the frame body 54 moves in the direction of the arrow C together with the frame body 54.

  On the other hand, when the second motor 62 is driven and the second drive screw shaft 64 is rotated in a predetermined direction, the grid 38 that engages with the second drive screw shaft 64 has an arrow under the guide action of the guide rail 60. Move in the D direction. Accordingly, the grid 38 is moved by a predetermined distance in the direction of the arrow C1 and the direction of the arrow D1 in FIG. 6, and is arranged at a position where the first mark 44 and the second mark 46 coincide.

  Note that each time the position of the grid 38 is adjusted, the solid detector 36 is irradiated with radiation as described above, and the radiographic image information is read from the solid detector 36, and the first mark 44 and the second mark are read. A relative position with respect to the mark 46 is detected. Then, when it is detected that the first mark 44 and the second mark 46 coincide with each other by reading the radiation image information, the adjustment by the adjustment mechanism 48 ends.

  Thus, in the first embodiment, the position of the grid 38 is adjusted in the direction of the arrow C and the direction of the arrow D via the adjustment mechanism 48, and the second mark 46 provided on the grid 38 and the solid state detector. The adjustment work is performed so that the first mark 44 provided on 36 matches. Therefore, the grid 38 can be accurately and reliably positioned with respect to the solid detector 36.

  In addition, for example, it is not necessary to position the grid 38 and the solid detector 36 with a positioning structure having an uneven portion. Thereby, an increase in manufacturing cost can be prevented, and there is an advantage that versatility can be easily improved with a simple and economical configuration.

  In the first embodiment, the grid 38 is mounted in the casing 26a. However, the grid 38 may be configured to be detachable from the casing 26a integrally with the adjustment mechanism 48. At that time, it is preferable that the adjustment work by the adjustment mechanism 48 is performed each time the grid 38 is attached.

  FIG. 6 is a schematic perspective explanatory view of a main part of an imaging table 90 constituting a radiographic image information imaging apparatus according to the second embodiment of the present invention. Note that the same reference numerals are assigned to the same components as those of the imaging stand 26 constituting the mammography apparatus 10 according to the first embodiment, and detailed description thereof is omitted.

  In the second embodiment, an adjustment mechanism 92 is provided that can adjust the position of the solid state detector 36 in the directions of arrows C and D, which are biaxial directions parallel to the surface 36a. Therefore, in the second embodiment, the position of the solid detector 36 is adjusted under the action of the adjustment mechanism 92 so that the first mark 44 of the solid detector 36 and the second mark 46 of the grid 38 coincide. The same effects as those of the first embodiment can be obtained.

  The present invention is not limited to the above-described embodiment, and various image receiving units can be employed. Specifically, the image receiving unit is, for example, a method that uses an intensifying screen and a radiographic film in close contact with each other, a method that uses a radiation detector made of a stimulable phosphor, and a digital that directly detects radiation in real time. This includes a method using a radiation detector (solid-state photodetector) for output.

1 is a perspective explanatory view of a mammography apparatus according to a first embodiment of the present invention. It is an internal block diagram of the imaging stand in the said mammography apparatus. It is a perspective explanatory view of a solid detector, a grid, and an adjustment mechanism arranged in the imaging stand. It is a block diagram of the control circuit which comprises the said mammography apparatus. It is explanatory drawing of the 1st mark of the said solid detector, and the 2nd mark of the said grid. It is an internal schematic perspective explanatory drawing of the imaging stand which comprises the mammography apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mammography apparatus 16 ... Base 20 ... Arm member 22 ... Subject 24 ... Radiation source storage part 26, 90 ... Imaging stand 30 ... Display operation part 34 ... Mammo 36 ... Solid state detector 38 ... Grid 40 ... Reading light source part 42 ... Erasing light source 44, 46 ... Mark 48, 92 ... Adjustment mechanism 50, 62 ... Motor

Claims (3)

In a radiographic image information imaging apparatus that converts a radiographic image of a subject into an electrical signal and reads it,
A radiation detector that detects radiation image information of the subject and is provided with a first mark;
A fixed grid that is disposed closer to the subject side than the radiation detection unit and provided with a second mark;
An adjustment mechanism capable of adjusting the position of the radiation detection unit or the fixed grid along the detection surface of the radiation detection unit so that the first mark and the second mark coincide with each other;
A radiographic image information imaging apparatus comprising:   The radiation image information imaging apparatus according to claim 1, wherein the adjustment mechanism includes an actuator capable of adjusting a position of the radiation detection unit or the fixed grid in two axial directions parallel to the detection surface. Image information photographing device.   The radiographic image information imaging device according to claim 1, further comprising a control unit that controls the adjustment mechanism based on radiographic image information of the first mark and the second mark obtained from the radiation detection unit. A radiographic image information photographing apparatus as a feature.

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