JP2008245991A - Radiographic image correction device and radiographic image photographing apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic image correction device capable of providing a desired radiographic image by appropriately correcting unevenness occurring in a radiographic image information detector even when the dose of a radiation is changed, and to provide a radiographic image photographing apparatus equipped with the same. <P>SOLUTION: Mammography equipment 10 being the radiographic image photographing apparatus includes: a radiation source 20 for emitting the radiation to a subject 18; and a solid detector 38 for detecting the dose of the radiation transmitting the subject 18 and acquiring radiographic image data. The mammography equipment 10 also is equipped with the radiographic image correction device 11 which includes: a correction data table storage part 60 stored with correction data in the radiations of the plurality of doses in each pixel being the plurality of measurement positions of the solid detector 38; and a data correction part 62 for correcting the radiographic image data acquired by the solid detector 38, based on the correction data corresponding to each dose radiated to each pixel of the solid detector 38. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiographic image correction apparatus that corrects radiographic image data detected by a radiographic image information detector, and a radiographic image capturing apparatus including the radiographic image correction apparatus.

  2. Description of the Related Art In the medical field, a wide range of radiographic imaging apparatuses that acquire radiation image data (radiation image information) by exposing radiation from a radiation source to a subject (patient), detecting radiation transmitted through the subject with a radiation detector, in use.

  In this type of radiographic imaging apparatus, so-called shading, that is, uneven sensitivity between pixels of the radiation detector (radiation image information detector) may occur.

  Therefore, the applicant of the present invention disclosed in Patent Document 1 that the stimulable phosphor sheet on which a radiographic image is recorded is irradiated with excitation light, and the stimulated emission light emitted from the stimulable phosphor sheet has a plurality of pixels. A radiological image correction apparatus that detects a photoelectric conversion means as a detector and corrects (shading correction) the obtained radiographic image data is proposed.

  Furthermore, the present applicant relates to the above-described shading correction, and in Patent Document 2, as a shading correction method in thermal recording to be recorded on a thermal recording material, the shading correction condition is changed according to the recording density, and a high-quality image is obtained. It proposes a stable recording method.

JP 2006-267427 A Japanese Patent Laid-Open No. 10-166640

  According to the radiological image correction apparatus described in Patent Document 1, appropriate radiographic image data can be obtained by performing shading correction on the radiation detector. However, the above-described shading may change depending on the dose of radiation applied to the radiation detector.

  Therefore, when radiation of a dose different from the dose at the time of obtaining correction data used for shading correction is irradiated on the radiation detector, it is desirable to perform correction to suppress unevenness caused by changes in the dose.

  The present invention has been made in relation to the above-described conventional technology, and even when the radiation dose changes, the unevenness generated in the radiation image information detector is appropriately corrected to obtain a desired radiation image. It is an object of the present invention to provide a radiological image correction apparatus that can be obtained and a radiographic imaging apparatus including the radiological image correction apparatus.

  A radiological image correction apparatus according to the present invention is a radiological image correction apparatus that detects a radiation dose irradiated to a subject from a radiation source and transmitted through the subject by a radiological image information detector and corrects the acquired radiographic image data. Sensitivity distribution storage means storing sensitivity distributions at a plurality of doses of radiation at a plurality of measurement positions of the radiation image information detector, and the radiation image data acquired by the radiation image information detector, the measurement positions Correction means for correcting based on the sensitivity distribution corresponding to each of the doses irradiated to the head.

  A radiographic image capturing apparatus according to the present invention includes a radiation source that irradiates a subject with radiation, a radiation image information detector that detects a radiation dose transmitted through the subject, and obtains radiation image data; and Sensitivity distribution storage means storing sensitivity distributions at a plurality of doses of radiation at a plurality of measurement positions of the radiation image information detector, and the radiation image data acquired by the radiation image information detector are irradiated to the measurement positions. And correction means for correcting based on the sensitivity distribution corresponding to each dose.

  According to the present invention, the radiation image data detected at each measurement position of the radiation image information detector is corrected using the sensitivity distribution in a plurality of doses of radiation. That is, even if the radiation dose irradiated to the radiation image information detector changes, it is based on the sensitivity distribution according to the dose received at each measurement position for each radiation image data at each measurement position. Shading correction can be performed. Therefore, unevenness between the measurement positions of the radiation image information detector, which changes due to a change in the radiation dose, can be effectively reduced, and a desired radiation image can be formed.

  Hereinafter, a radiographic image correction apparatus according to the present invention will be described in detail with reference to the accompanying drawings by giving preferred embodiments in relation to a radiographic imaging apparatus equipped with this apparatus.

  FIG. 1 is an explanatory perspective view of a mammography apparatus 10 as a radiographic imaging apparatus according to an embodiment of the present invention. In the present embodiment, a mammography apparatus 10 used for breast cancer screening and the like will be exemplified to describe a radiological image correction apparatus according to the present invention and a radiographic image capturing apparatus including the radiographic image correction apparatus. Of course, it is not limited to this.

  The mammography apparatus 10 includes a base 12 that is installed in an upright state, an arm member 16 that is fixed to a turning shaft 14 that is disposed at a substantially central portion of the base 12, and an imaging part (imaging part) of a subject 18. The radiation source 20 for exposing the breast to the radiation is housed, the radiation source housing portion 22 fixed to one end of the arm member 16, and the arm member 16 disposed opposite to the radiation source housing portion 22. An imaging table 24 fixed to the other end of the imaging table 24 and a compression plate (pressing plate) 26 that presses and holds the breast against the imaging table 24 are provided.

  The arm member 16 to which the radiation source storage unit 22 and the imaging table 24 are fixed is configured to be adjustable in the imaging direction with respect to the breast of the subject 18 by rotating in the direction of arrow A about the rotation axis 14. The compression plate 26 is disposed between the radiation source storage unit 22 and the imaging table 24 in a state of being connected to the arm member 16 and is configured to be displaceable in the arrow B direction.

  The base 12 displays photographing information of the subject 18 detected by the mammography apparatus 10, photographing information such as a photographing direction, ID information of the subject 18, and the like, and the information can be set as necessary. A display operation unit 28 is provided.

  FIG. 2 is a main part explanatory diagram showing an internal configuration of the imaging stand 24 in the mammography apparatus 10, and shows a state where a breast (mammo) 34 that is an imaging region of the subject 18 is arranged between the imaging stand 24 and the compression plate 26. . Reference numeral 36 indicates the chest wall of the subject 18.

  In the imaging stand 24, radiation image data (radiation image information) imaged based on the radiation X output from the radiation source 20 incorporated in the radiation source storage unit 22 is accumulated and output as an electrical signal. A detector (radiation image information detector, image sensor) 38, a reading light source unit 40 for irradiating the solid detector 38 with reading light in order to read the radiation image data stored and recorded in the solid detector 38, and solid detection An erasing light source unit 42 that irradiates the device 38 with erasing light is housed.

  Further, a grid 44 for removing scattered components of the radiation X generated in the breast 34 that is a subject is provided on the upper portion of the solid detector 38 (between the radiation source storage unit 22 and the solid detector 38). For example, the grid 44 is formed as a slit in which a plurality of lead plates are arranged in a grid pattern in one direction to remove the scattering component, and in order to prevent image unevenness due to the lead plates, FIG. Can be reciprocated in the direction of arrow C. The grid 44 can be omitted depending on the use conditions of the mammography apparatus 10 and the like.

  The solid state detector 38 is a direct conversion type and optical readout type radiation solid state detector that accumulates radiation image data based on the radiation X transmitted through the breast 34 as an electrostatic latent image and reads it from the reading light source unit 40. By scanning with light, a current corresponding to the electrostatic latent image is generated.

  As the solid state detector 38, for example, one having a structure disclosed in Japanese Patent Application Laid-Open No. 2004-154409 can be used. Specifically, the solid state detector 38 is formed on a glass substrate and has a first conductive layer that transmits radiation X and The recording photoconductive layer that generates a charge when exposed to radiation X and the latent image polar charge charged in the first conductive layer act as an insulator while being opposite to the latent image polar charge. A charge transport layer that acts as a substantially conductive material for the polar transport polar charge, a read photoconductive layer that exhibits electrical conductivity when irradiated with read light, and a second that transmits radiation X It is configured as a solid-state detection element in which conductive layers are sequentially stacked. 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 data 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.

  The reading light source unit 40 includes, for example, a line light source configured by arranging a plurality of LED chips in a line, and an optical system that linearly irradiates the reading light output from the line light source onto the solid state detector 38, The line light source in which the LED chips are arranged in a direction orthogonal to the extending direction of the linear electrode which is the second conductive layer of the solid state detector 38 is moved in the extending direction of the linear electrode (arrow C direction in FIG. 3). By doing so, the entire surface of the solid state detector 38 is exposed and scanned. As shown in FIG. 3, such a reading light source unit 40 is moved in the direction of arrow C (sub-scanning direction) by a driving unit configured by a conveyance mechanism 43 configured by a belt pulley mechanism, a guide rail 45, and the like. It is movable.

  As shown in FIG. 3, the erasing light source unit 42 is configured by arranging a large number of LED chips 46 on a panel 48 that emit and extinguish light in a short time and have very little afterglow. The panel 48 is housed in the imaging table 24 in a state of being arranged in parallel with the solid state detector 38.

  FIG. 4 is a block diagram of a control circuit constituting the mammography apparatus 10.

  The control circuit of the mammography apparatus 10 is housed in the radiation source housing section 22, and a radiation source control section (radiation source control means) 54 for controlling the radiation source 20 that emits radiation X by operating the exposure switch 52; An imaging condition setting unit that sets various imaging conditions, calculates an appropriate exposure time of the radiation X from the radiation source 20 based on the set imaging conditions, and supplies the exposure control conditions to the radiation source control unit 54 (Exposure condition setting means) 58.

  The imaging conditions set by the imaging condition setting unit 58 include the conditions relating to the target and filter provided in the radiation source 20, the presence or absence of the grid 44, the size of the opening of the target, that is, the large focus (contact imaging). ) And small focus (enlarged shooting) conditions, application time of high voltage to the solid state detector 38 during shooting (high voltage time), information on the dose of radiation X detected by the solid state detector 38, etc. It is done. Each of these imaging conditions is supplied to the imaging condition setting unit 58 when the engineer directly inputs the operation by operating the display operation unit 28 or as an electrical signal from the radiation source 20 or the solid state detector 38. There is a case.

  Further, the control circuit of the mammography apparatus 10 corrects the radiation image data detected by the solid state detector 38 based on the correction data (sensitivity distribution) stored in the correction data table storage unit (sensitivity distribution storage means) 60. A correction unit (correction means) 62 is provided. The data correction unit 62 is provided with a storage unit (memory) 64 in which the radiation image data, the corrected radiation image data, and the like are stored. In addition to the radiation image data, the data correction unit 62 is supplied with information regarding various imaging conditions set by the imaging condition setting unit 58.

  Further, the control circuit of the mammography apparatus 10 includes a radiation image forming unit 66 that forms a radiation image based on the corrected radiation image data corrected by the data correction unit 62, and a display unit 68 that displays the radiation image. Prepare.

  The mammography apparatus 10 of the present embodiment is basically configured as described above. However, in the solid state detector 38 as a radiation detector as described above, the sensitivity between pixels is determined by the dose of radiation applied. The shape and size of unevenness (shading) (hereinafter referred to as unevenness level), in other words, the sensitivity unevenness of the solid state detector 38 itself changes. The uneven sensitivity between the pixels is, for example, an output between the reference output and the actual output of each pixel when the same reference output is set for all the pixels constituting the solid state detector 38. It is a difference. In addition, since the radiation dose varies depending on the imaging conditions, the unevenness level varies depending on the imaging conditions. Furthermore, if there is unevenness in the amount of light in the line direction of the reading light source unit 40, the unevenness level changes depending on the radiation dose.

  That is, first, in the mammography apparatus 10 according to the present embodiment, radiation image data is read by scanning the reading light source unit 40 and exposing the entire surface of the solid state detector 38. In the case of such an optical reading method, In some cases, the output level (size) of the radiation image data read from the solid state detector 38 may vary depending on the light amount level (size) of the reading light source unit 40 (see FIG. 5). In such a case, if the amount of light in the line direction of the reading light source unit 40 is uneven, the unevenness level of the solid state detector 38 changes depending on the radiation dose.

  That is, as shown in FIGS. 5 and 6, at a high dose (for example, the H position in FIG. 5), the sensitivity unevenness between the pixels of the solid state detector 38 in the line direction of the reading light source unit 40 increases. At a low dose (for example, see L in FIG. 5), the sensitivity unevenness between the pixels of the solid state detector 38 in the line direction of the reading light source unit 40 tends to be small.

  Secondly, the unevenness level varies depending on the above-described various imaging conditions, that is, conditions relating to the target and filter, presence / absence of the grid 44, conditions relating to the large focus and small focus, and the high pressure time of the solid state detector 38.

  Thirdly, the solid-state detector 38 normally performs so-called pre-reading, in which the reading light source unit 40 is exposed and scanned in a state where no radiation is irradiated, thereby detecting afterimage data of the solid-state detector 38 itself. . The output of each pixel of the solid state detector 38 acquired by this pre-reading (hereinafter referred to as pre-read data) is also used to expose and scan the reading light source unit 40 after the subject 18 is placed and exposed to radiation. A so-called main reading is performed, and afterimage correction is performed to correct the output (radiation image data) of each pixel (each measurement position) of the solid state detector 38 acquired by the main reading, and the afterimage data of the solid state detector 38 is corrected. Yes. That is, generally, in such afterimage correction, correction processing is performed in which the pre-read data acquired by pre-reading is subtracted (subtracted) from the radiation image data acquired by main reading.

  However, in reality, when the solid state detector 38 is irradiated with the radiation X, the sensitivity unevenness (unevenness level) of the solid state detector 38 itself varies depending on the magnitude of the dose. For this reason, in the correction process in which the pre-read data is simply subtracted from the radiation image data acquired in the main reading as described above, the unevenness in sensitivity of the solid state detector 38 corresponding to the amount of the dose is appropriately corrected. The remaining sensitivity unevenness affects the radiographic image.

  As described above, in the radiographic image capturing apparatus such as the mammography apparatus 10 according to the present embodiment, the unevenness level of the radiation detector (solid detector 38) varies depending on the radiation dose, and therefore the same for all radiographing. If level shading correction is performed, it is difficult to sufficiently reduce the sensitivity unevenness of the radiation detector.

  Therefore, the operation of the mammography apparatus 10 including the data correction unit 62 for correcting the sensitivity variation of the solid state detector 38 that changes as described above will be described with reference to the flowchart of FIG.

  First, in step S1 of FIG. 7, preparation for imaging the breast 34, which is the imaging region of the subject 18, is performed.

  It should be noted that when making this preparation for shooting, correction data used for shading correction performed by the data correction unit 62 described later needs to be created in advance and stored in the correction data table storage unit 60. Here, the correction data table storage unit 60 stores a plurality of correction data tables created according to the magnitude of the radiation X dose. For example, in the case of the present embodiment, a high dose is stored. A correction data table for (high dose) and a correction data table for low dose (low dose) are stored. The high dose is, for example, 104 μGy (12 mR) or more, and the low dose is, for example, 87 μGy (10 mR) or less.

  Specifically, each correction data table as described above can be created by exposing a plurality of doses of radiation X from the radiation source 20 in a state where the subject 18 is not disposed. That is, after irradiating the solid detector 38 with a high dose of radiation in a state where the subject 18 is not arranged, the solid detector 38 is scanned with the reading light of the reading light source unit 40, and based on the obtained radiation image data. High dose correction data can be created. Similarly, after irradiating the solid state detector 38 with a low dose of radiation without the subject 18 being arranged, the solid state detector 38 is scanned with the reading light of the reading light source unit 40, and the obtained radiation image data is obtained. Based on this, low-dose correction data can be created.

  Further, the high dose and low dose correction data created in this way are used for the above-described various imaging conditions, that is, conditions relating to the target and filter, presence or absence of the grid 44, conditions relating to the large focus and small focus, and the solid state detector 38. The correction data tables for the high dose and the low dose can be created by correcting according to the high-pressure time, or by correcting the correction data for both doses for each of these imaging conditions. Therefore, the correction data table storage unit 60 stores both correction data tables created in advance as described above. The creation of such a correction data table may be performed, for example, every day when the mammography apparatus 10 is activated, every fixed number of days, or before every photographing.

  In the state where the predetermined correction data table is stored in the correction data table storage unit 60 as described above, the preparation for shooting in step S1 is performed.

  That is, first, ID information related to the subject 18, a photographing method, and the like are set using a console, an ID card, etc. (not shown). In this case, the ID information includes information such as the name, age, and sex of the subject 18 and can be acquired from an ID card possessed by the subject 18. In addition, when the mammography apparatus 10 is connected to a network, it can be acquired from another apparatus on the network. In addition, the imaging method includes information such as an imaging part and an imaging direction instructed by a doctor, which can be acquired from a higher-level device connected to the network or input by a radiologist from the console. These pieces of information can be displayed and confirmed on the display operation unit 28 of the mammography apparatus 10.

  Subsequently, the radiologist sets the mammography apparatus 10 to a predetermined state according to the designated imaging method. For example, as the imaging direction of the breast 34, head-to-tail (CC) imaging in which radiation X is applied from the upper side, imaging in which side X (ML) imaging is performed by exposing the radiation X from the side, oblique There is an inside / outside oblique (MLO) imaging in which radiation X is emitted from the direction and imaging is performed, and the arm member 16 is turned around the turning axis 14 in accordance with these imaging directions.

  Next, the breast 34 of the subject 18 is positioned with respect to the mammography apparatus 10. That is, after the breast 34 is placed on the imaging table 24, the compression plate 26 is pushed down to hold the breast 34 between the imaging table 24 and the compression plate 26 (see FIG. 2).

  After the above preparatory work is completed, in step S2, so-called pre-reading is performed in which the entire surface of the solid state detector 38 is exposed and scanned with the reading light from the reading light source unit 40 in a state where the radiation X is not exposed.

  The output from each pixel of the solid state detector 38 obtained by the pre-reading, that is, the pre-read data Pin (i, j) is stored in the storage unit 64 of the data correction unit 62 (step S3). The above (i, j) is the pixel number (coordinate) of each pixel constituting the solid state detector 38, and the same applies to other data described below.

  Next, imaging of the breast 34 is started. That is, first, the radiation source control unit 54 sets the tube current supplied to the radiation source 20 to a current that provides a predetermined radiation dose based on the exposure control conditions set by the imaging condition setting unit 58. Next, when the radiologist operates the exposure switch 52, the radiation X is exposed to the breast 34 while the radiation source 20 is controlled by the current, and the exposure time set as the exposure control condition has elapsed. Thereafter, the exposure to the radiation X is stopped (step S4).

  In the mammography apparatus 10, an AEC (Automatic Exposure Control) sensor, which is a detector for automatic exposure control, or the like can be separately arranged behind the solid state detector 38 in the propagation direction of the radiation X. Then, the radiation dose during the exposure to the breast 34 is detected by the AEC sensor and the integrated amount is calculated, and the radiation dose of the radiation X reaches the allowable amount before reaching the set exposure time. If it exceeds, the radiation source controller 54 is controlled to forcibly stop the radiation X from being emitted from the radiation source 20, so that the subject 18 is exposed to excessive radiation X due to a failure of the mammography apparatus 10 or the like. The situation can be prevented in advance.

  In step S4, when the radiation X transmitted through the breast 34 held between the compression plate 26 and the imaging table 24 reaches the solid state detector 38 accommodated in the imaging table 24, the solid state detector 38 Radiation image data Din (i, j), which is dose data of each pixel, is recorded.

  Therefore, after the imaging of the breast 34 is completed, when the reading light source unit 40 moves in the direction of arrow C in FIG. 3 along the solid detector 38 and is irradiated with reading light, the radiation recorded in the solid detector 38 is recorded. The image data Din (i, j) is read (main reading) and stored in the storage unit 64 of the data correction unit 62 (steps S5 and S6). That is, radiation dose data at each pixel of the solid state detector 38 is acquired as radiation image data Din (i, j) and stored in the storage unit 64. The radiation image data Din (i, j) at each pixel differs as the dose from the radiation source 20 changes depending on the measurement position (pixel position). Naturally, the radiation X is absorbed by the breast 34. It will also be different.

  Subsequently, in step S7, the radiation image data Din (i, j) acquired in step S6 is subjected to shading correction using the correction data stored in the correction data table storage unit 60.

  Therefore, such a shading correction method will be described in detail below.

  First, as described above, the correction data table storage unit 60 has a plurality of correction data tables corresponding to the dose of radiation X. In the present embodiment, for example, a high dose (high dose) A correction data table for (dose) and a correction data table for a low dose (low dose) are stored.

  Therefore, when shading correction is performed on the radiation image data Din (i, j), the magnitude of the radiation dose reaching each pixel of the solid state detector 38, that is, the radiation image data Din (i, j) at each pixel. The correction data used for actual correction may be calculated by changing the weighting of the high dose and low dose correction data tables according to the magnitude of j), and correction using this correction data may be performed.

That is, for example, the correction data on the low-dose correction data table shown in FIG. 8A is referred to as SL (i, j), and the correction data on the high-dose correction data table shown in FIG. 8A is SH (i, j). The correction data SC (i, j), which is calculated using both and used for the shading correction in the implementation, is referred to as SC (i, j).
SC (i, j) = a.SL (i, j) + b.SH (i, j)

  In the above equation, a and b are weighting coefficients, and a + b = 1, which is a coefficient changed by dose data at each pixel of the solid state detector 38, that is, radiation image data. For example, when the predetermined pixel (i, j) is a high-dose pixel, b is increased, and conversely, when the predetermined pixel (i, j) is a low-dose pixel, a is increased. Further, in the present embodiment, the correction data SC (i, j) is calculated by linearly interpolating each of the correction data SL (i, j) and SH (i, j) and changing the weights to obtain the correction data SC (i, j). Correction data at a dose located between the dose and the low dose can be calculated, and suitable shading correction corresponding to a change in the dose of radiation X can be performed more smoothly (see FIG. 9).

  Therefore, the radiographic image data of the image recorded for calculating the low dose correction data SL (i, j) is referred to as CL, and the radiographic image recorded for calculating the high dose correction data SH (i, j). When the data is referred to as CH and the first corrected radiation image data, which is the data after correcting the radiation image data Din (i, j), is referred to as Dout1 (i, j), first, the radiation image data Din (i J) <low-dose radiation image data CL, SC (i, j) = SL (i, j).

  Second, when low dose image data CL ≦ radiation image data Din (i, j) ≦ high dose image data CH, SC (i, j) = [(Dout1 (i, j) − CL) .SH (i, j) + (CH-Dout1 (i, j)). SL (i, j)] / (CH-CL).

  Thirdly, SC (i, j) = SH (i, j) when radiation image data Din (i, j)> high-dose image data CH.

Therefore, the data correction unit 62 performs the shading correction on the radiation image data Din (i, j) using the correction data SC (i, j) calculated as described above, as shown in the following equation. First corrected radiation image data Dout1 (i, j) is calculated and stored in the storage unit 64 (step S8).
Dout1 (i, j) = Din (i, j). (1 + SC (i, j))

  As described above, the data correction unit 62 selects a high-dose or low-dose correction data table for each pixel in accordance with the dose of interest of imaging, and performs shading correction using correction data corresponding to the dose of each pixel. Thus, the sensitivity unevenness of the solid state detector 38 that changes according to the dose can be corrected appropriately.

  The data correction unit 62 performs the shading correction on the radiation image data Din (i, j) as described above. On the other hand, in step S9, the pre-read data Pin (i, i) is obtained based on the correction data SC (i, j). , J) is corrected (shading correction), and as a result, corrected pre-read data Pout (i, j) is calculated and stored in the storage unit 64 (step S10). The shading correction method in this case is the shading for the radiation image data described above except that the low-dose correction data table or another correction data table created for the pre-read data Pin (i, j) is used. Since it is substantially the same as the correction method, detailed description is omitted. Further, such steps S9 and S10 may be executed simultaneously with or before the above-described steps S7 and S8, that is, if correction data SC (i, j) is calculated. .

  In step S11, afterimage correction is performed by subtracting the corrected pre-read data Pout (i, j) calculated in step S10 from the first corrected radiation image data Dout1 (i, j) acquired in step S8. As a result, the second corrected radiation image data Dout2 (i, j) is calculated as the data after the afterimage correction, and is stored in the storage unit 64 (step S12).

  As described above, in the present embodiment, the afterimage correction of the first corrected radiation image data Dout1 (i, j) is performed using the corrected pre-read data Pout (i, j) that has been subjected to the shading correction. Thereby, it is possible to perform shading correction in consideration of the sensitivity unevenness of the solid state detector 38 itself that has changed according to the magnitude of the radiation dose. In other words, in the case of the present embodiment, afterimage correction can be performed in consideration of unevenness in sensitivity of the solid state detector 38 that has changed due to the dose, and thus more appropriate shading correction can be performed.

  Finally, the second corrected radiation image data Dout2 (i, j) obtained as described above is supplied to the radiation image forming unit 66 to form a radiation image, which is displayed on the display unit 68. (Step S13). Thereafter, the solid state detector 38 from which the radiographic image data has been read is irradiated with erasing light emitted from the erasing light source unit 42 to remove the accumulated unnecessary charges in order to perform the next imaging.

  As described above, in the mammography apparatus 10 that is the radiographic image capturing apparatus according to the present embodiment, the data correction unit 62 and the correction data table storage unit 60 function as the radiographic image correction apparatus 11 (see FIG. 4). As functions of the correction device 11, step S3 and steps S7 to S12 shown in FIG. 7 are executed. Thereby, even when the dose irradiated from the radiation source 20 and reaches the solid detector 38 changes, the output (radiation image data) of each pixel (measurement position) constituting the solid detector 38 is changed. The shading correction based on the correction data (sensitivity distribution) corresponding to the received dose can be performed. Therefore, the sensitivity unevenness of the solid state detector 38 that changes according to the dose can be corrected appropriately, and a desired radiation image can be reliably formed.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change freely in the range which does not deviate from the main point of this invention.

  For example, the afterimage correction in step S11 in FIG. 7 is not necessarily performed, and may be omitted depending on the shooting conditions.

  Further, the number of correction data tables stored in the correction data table storage unit 60 may be changed to, for example, three or more according to the radiation dose.

  Further, in the above embodiment, the case where the solid state detector 38 is used has been described. However, the present invention also relates to a radiographic image capturing apparatus configured so that the stimulable phosphor sheet is detachably attached to the imaging table 24. A radiation image correction apparatus can be applied. In this case, the radiological image correction apparatus does not have a radiation source or an imaging stand, and has a reading light source unit, and reads and corrects the data of the stimulable phosphor sheet on which the radiographic image data is separately recorded and corrects the radiographic image reading. It can be configured as a device.

  Furthermore, it goes without saying that the radiographic image capturing apparatus according to the present invention is not limited to the mammography apparatus illustrated in the above embodiment, but can be applied to a radiographic image capturing apparatus that captures other parts of the subject. .

It is a perspective explanatory view of a mammography device as a radiographic imaging device concerning one embodiment of the present invention. It is principal part explanatory drawing which shows the internal structure of the imaging stand in the mammography apparatus shown in FIG. FIG. 3 is a partially omitted cutaway perspective view showing an internal configuration of the photographing stand shown in FIG. 2. It is a block diagram of the control circuit which comprises the mammography apparatus shown in FIG. It is a graph which shows the relationship between the radiation dose by the reading light quantity level, and the output of a solid state detector. It is a graph which shows the relationship between the nonuniformity level of reading light quantity, and the nonuniformity level of a radiation dose. It is a flowchart which shows operation | movement of the mammography apparatus shown in FIG. FIG. 8A is a graph showing correction data for a low dose, and FIG. 8B is a graph showing correction data for a high dose. It is a graph which shows the weighting of the correction data in each dose concerning calculation of the correction data used for shading correction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mammography apparatus 11 ... Radiation image correction apparatus 18 ... Subject 20 ... Radiation source 22 ... Radiation source storage part 24 ... Imaging stand 34 ... Breast 38 ... Solid state detector 40 ... Reading light source part 42 ... Erase light source part 44 ... Grid 54 ... Radiation source control unit 58 ... imaging condition setting unit 60 ... correction data table storage unit 62 ... data correction unit 64 ... storage unit 66 ... radiation image forming unit 68 ... display unit

Claims (4)

A radiation image correction apparatus that detects a radiation dose irradiated to a subject from a radiation source and transmitted through the subject by a radiation image information detector, and corrects the acquired radiation image data,
Sensitivity distribution storage means for storing sensitivity distributions at a plurality of doses of radiation at a plurality of measurement positions of the radiation image information detector;
Correction means for correcting the radiation image data acquired by the radiation image information detector based on the sensitivity distribution corresponding to each dose irradiated to each measurement position;
A radiation image correction apparatus comprising: A radiation source for exposing the subject to radiation,
A radiation image information detector for detecting a radiation dose transmitted through the subject and acquiring radiation image data;
Sensitivity distribution storage means for storing sensitivity distributions at a plurality of doses of radiation at a plurality of measurement positions of the radiation image information detector;
Correction means for correcting the radiation image data acquired by the radiation image information detector based on the sensitivity distribution corresponding to each dose irradiated to each measurement position;
A radiographic imaging apparatus comprising: In the radiographic imaging device of Claim 2,
The radiographic image capturing apparatus, wherein the radiographic image information detector is a solid state detector using a solid state detecting element. In the radiographic imaging device of Claim 2 or 3,
A radiographic imaging apparatus comprising: a reading light source unit that emits reading light for reading out radiographic image data acquired by the radiographic image information detector.

Images