JP5032710B2 - Radiation imaging device - Google Patents

Description

  The present invention relates to a radiation image capturing apparatus that captures a radiation image by irradiating a breast with radiation output from a radiation source and detecting the radiation transmitted through the breast with a radiation detector.

  In the medical field, a radiation image capturing apparatus that captures a radiation image by irradiating a subject with radiation and detecting the transmitted radiation with a radiation detector is widely used.

  Here, as the radiation detector, for example, a large number of charge collecting electrodes formed in a matrix on an insulating substrate, and radiation conduction that is formed on the charge collecting electrode and generates charges according to the irradiated radiation. It has a solid-state detection unit that is laminated with the body, collects the charge related to the radiation image generated by the radiation conductor with the charge collection electrode, temporarily stores it in the power storage unit, converts the stored charge into an electric signal and outputs it What to do is known. As other radiation detectors, those using a charge coupled device (CCD) and those combining amorphous silicon and a scintillator are also known. Furthermore, when radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.) is irradiated, a part of the radiation energy is accumulated, and then excitation light such as laser light or visible light is irradiated. Thus, a stimulable phosphor panel using a stimulable phosphor exhibiting stimulated emission corresponding to the stored energy can be used as a radiation detector.

  By the way, when capturing a radiation image using such a radiation detector, in order to acquire a high-quality radiation image, it is necessary to set an appropriate irradiation dose according to the radiation transmittance of the imaging region of the subject. is there. In particular, when the imaging site is the breast, the radiation transmittance varies greatly depending on the thickness of the breast and the density of the mammary gland, so the necessary radiation dose is adjusted according to the state of the breast and excessive radiation is applied. It is extremely important to control so as to avoid this.

  Therefore, in Patent Document 1 or 2, pre-exposure was performed to irradiate a subject with a small amount of radiation, detect the transmitted radiation dose with a radiation detector, and calculate the irradiation dose necessary for imaging. Thereafter, a conventional technique is disclosed in which main exposure is performed in which a subject is irradiated with radiation having a calculated irradiation dose to capture a radiographic image.

Japanese Patent Laid-Open No. 7-153592 JP 2003-115399 A

  However, since the radiation that reaches the radiation detector varies greatly depending on the thickness of the breast and the density of the mammary gland, as in Patent Document 1 or 2, if the irradiation dose at the time of pre-exposure is set constant, If the radiation detector is not irradiated with a necessary dose of radiation or excessive radiation is applied to the radiation detector, the irradiation dose may not be detected with high accuracy. Also, during pre-exposure, if excessive radiation exceeding the irradiation dose necessary for imaging is irradiated to the breast, not only unnecessary radiation will be irradiated, but this exposure itself will be impossible. End up.

  The present invention has been made to solve the above-described problems, and can calculate the irradiation dose necessary for capturing the radiation image of the breast with high accuracy and without irradiating excessive radiation. An object of the present invention is to provide a radiographic imaging device capable of obtaining a high-quality radiographic image.

In the radiographic image capturing apparatus of the present invention, a radiation image is captured by irradiating a breast with radiation output from a radiation source and detecting the radiation transmitted through the breast with a radiation detector.
A dose detection sensor for detecting a dose of the radiation transmitted through the breast;
A thickness measuring device for measuring a breast thickness with respect to a radiation transmission direction when the breast is pressed against the radiation detector by a compression plate;
Tube current setting means for setting a tube current to be supplied to the radiation source;
Pre-exposure required irradiation that calculates pre-exposure required irradiation time required for pre-exposure to irradiate the radiation to the breast prior to the main exposure for capturing the radiation image, using the measured breast thickness as a parameter A time calculator,
The main exposure required irradiation time required for the main exposure is calculated based on the pre-exposure irradiation dose based on the pre-exposure irradiation dose detected by the dose detection sensor. A necessary irradiation time calculation unit,
The radiation source is controlled according to the tube current and the pre-irradiation required irradiation time, and the pre-exposure is performed, while the radiation source is controlled according to the tube current and the main irradiation necessary irradiation time, and the main exposure is performed. A radiation source control unit for performing
It is characterized by providing.

Further, the radiographic image capturing apparatus of the present invention irradiates a breast with radiation output from a radiation source and detects a radiographic image by detecting the radiation transmitted through the breast with a radiation detector. In
A dose detection sensor for detecting a dose of the radiation transmitted through the breast;
A thickness measuring device for measuring a breast thickness with respect to a radiation transmission direction when the breast is pressed against the radiation detector by a compression plate;
Tube current setting means for setting a tube current to be supplied to the radiation source;
Prior to the main exposure for capturing the radiographic image, the pre-exposure required current, which is a tube current required for pre-exposure to irradiate the radiation to the breast, is measured with the measured breast thickness and predetermined pre-exposure required. A pre-exposure current control unit that controls based on the irradiation time;
Necessary for the main exposure based on the pre-exposure irradiation dose and the tube current set by the tube current setting means, with the dose at the pre-exposure detected by the dose detection sensor being a pre-exposure irradiation dose A main irradiation required irradiation time calculating unit for calculating a main irradiation required irradiation time,
The radiation source is controlled according to the pre-exposure required current and the pre-exposure required irradiation time and performs the pre-exposure, while the tube current setting means sets the tube current and the main exposure required irradiation time. A radiation source controller that controls the radiation source and performs the main exposure;
It is characterized by providing.

  In the radiographic imaging device of the present invention, the irradiation necessary for the pre-exposure is performed by calculating the irradiation time or the tube current according to the irradiation dose necessary for the pre-exposure based on the thickness of the breast and performing the pre-exposure. The irradiation time corresponding to the dose can be calculated with high accuracy, and excessive irradiation of radiation to the breast can be avoided.

  Moreover, a high quality radiographic image can be obtained by controlling the radiation source in accordance with the main irradiation required irradiation time calculated with high accuracy.

  Furthermore, the moving grid is controlled by controlling the moving speed of the moving grid according to the calculated irradiation time in the pre-exposure or main exposure and the grid speed setting table indicating the relationship between the irradiation time and the moving speed of the moving grid. It is possible to avoid the occurrence of unevenness in the radiation image.

It is a block diagram of the mammography apparatus of this embodiment. It is an internal block diagram of the imaging stand in the mammography apparatus of this embodiment. It is an internal perspective explanatory drawing of the imaging stand in the mammography apparatus of this embodiment. It is a block diagram of the control circuit which comprises the mammography apparatus of this embodiment. It is an operation | movement flowchart in the mammography apparatus of this embodiment. It is explanatory drawing of the relationship between the irradiation time of a radiation, and a grid speed. It is explanatory drawing of the irradiation time in the pre-exposure in the case of a thin breast, and this exposure. It is explanatory drawing of the irradiation time in the pre-exposure in the case of a thick breast, and this exposure. It is explanatory drawing of the tube current in the pre-exposure which controlled the tube current in the case of a thin breast, and this exposure. It is explanatory drawing of the tube current in the pre-exposure which controlled the tube current in the case of a thick breast, and this exposure. It is explanatory drawing of the relationship between a required irradiation dose and tube current.

  FIG. 1 is a configuration diagram of a mammography apparatus 20 that is an embodiment to which a radiographic image capturing apparatus of the present invention is applied.

  The mammography apparatus 20 includes a base 26 that is installed in an upright state, an arm member 30 that is fixed to a turning shaft 28 that is disposed at a substantially central portion of the base 26, and a breast 44 that is an imaging part of a subject 32. A radiation source 22 (FIG. 3) for irradiating radiation to (FIG. 2) is housed, and a radiation source housing portion 34 fixed to one end of the arm member 30 and radiation X transmitted through the breast 44 (FIG. 2) The solid-state detector 24 (FIGS. 2 and 3) (radiation detector) for acquiring the radiation image by detecting the radiation is housed and fixed to the other end portion of the arm member 30, and the imaging base 36 And a compression plate 38 that compresses and holds the breast 44.

  The arm member 30 to which the radiation source storage unit 34 and the imaging stand 36 are fixed is configured to be adjustable in the imaging direction with respect to the breast 44 of the subject 32 by turning in the direction of arrow A about the turning axis 28. The compression plate 38 is disposed between the radiation source storage unit 34 and the imaging base 36 in a state of being connected to the arm member 30 and is configured to be displaceable in the arrow B direction.

  In addition, on the base 26, the imaging part of the subject 32 detected by the mammography apparatus 20, imaging information such as the imaging direction, ID information of the subject 32, and the like can be displayed, and these information can be set as necessary. A display operation unit 40 is provided.

  2 and 3 are explanatory diagrams of the internal configuration of the imaging stand 36 in the mammography apparatus 20. FIG. 2 shows a state in which the breast 44, which is the imaging part of the subject 32, is disposed between the imaging stand 36 and the compression plate 38. FIG. Show. Reference numeral 45 indicates the chest wall of the subject 32.

  In the imaging stand 36, a solid state detector that accumulates as a charge information a moving grid 23 for removing scattered radiation of the radiation X output from the radiation source 22 and a radiation image based on the radiation X that has passed through the breast 44. 24, in order to read out the charge information accumulated in the solid state detector 24, a reading light source 48 that irradiates the solid state detector 24 with reading light, and an unnecessary charge accumulated in the solid state detector 24 are removed. An erasing light source 50 that irradiates the solid detector 24 with erasing light, and a dose detection sensor 52 that detects the dose of the radiation X transmitted through the solid detector 24 are disposed.

  The moving grid 23 is formed by alternately arranging a substance that absorbs the radiation X and a substance that transmits the radiation X so as to form a stripe shape or a lattice shape. It is configured to move or vibrate at a predetermined speed.

  The solid state detector 24 is a direct conversion type and optical readout type radiation solid state detector, which accumulates a radiographic image based on the radiation X transmitted through the breast 44 as an electrostatic latent image, and uses the reading light from the reading light source 48. By scanning, a current corresponding to the electrostatic latent image is generated.

  As the solid state detector 24, for example, one disclosed in Japanese Patent Application Laid-Open No. 2004-154409 can be used. Specifically, a first conductive layer that is formed on a glass substrate and transmits radiation X, and radiation The recording photoconductive layer that generates charges when irradiated with X, and acts as a substantially insulator for the latent image polar charge charged in the first conductive layer, while transporting the opposite polarity to the latent image polar charge A charge transport layer that acts as a substantially conductive material for polar charges, a read photoconductive layer that generates electrical charge when irradiated with read light, and a second conductive layer that transmits radiation X; 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 has a predetermined pixel pitch for detecting charge information related to a recorded radiographic image as an image signal. Configured as a number of linear electrodes. 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 48 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 detector 24, and is a solid state. A solid state is obtained by moving a line light source in which LED chips are arranged in a direction orthogonal to the extending direction of the linear electrode which is the second conductive layer of the detector 24 in the extending direction (arrow C direction) of the linear electrode. The entire surface of the detector 24 is exposed and scanned.

  The erasing light source 50 is configured by arranging LED chips that emit and extinguish light in a short time and have very little afterglow along a two-dimensional plane parallel to the solid state detector 24.

  The dose detection sensor 52 is a sensor that detects the dose of radiation X that has passed through the vicinity of the mammary gland of the breast 44, and a plurality of sensors can be arranged as necessary.

  FIG. 4 is a block diagram of a control circuit constituting the mammography apparatus 20.

  The mammography apparatus 20 includes an operation setting unit 54 (a line quality information setting unit, a tube quality setting unit, etc.) for setting subject information related to the age, sex, body type, subject identification number, etc. Current setting means) and the set imaging conditions, for example, tube current, tube voltage, target or filter type set to the radiation source 22, calculated radiation X irradiation dose, irradiation time, etc. From the radiation source control unit 56 (pre-exposure required irradiation time calculation unit, main exposure required irradiation time calculation unit, pre-exposure required current control unit, main exposure required irradiation time calculation unit) to be controlled, and the solid state detector 24 The moving speed of the moving grid 23 is controlled via the grid driving unit 60 according to the image processing unit 58 that performs image processing on the acquired radiation image of the breast 44 and the calculated radiation X irradiation dose. A grid control unit 62, and an irradiation dose calculation unit 64 that calculates an irradiation dose of radiation X necessary for capturing a radiographic image and supplies it to the radiation source control unit 56 and the grid control unit 62 (pre-exposure required irradiation dose calculation unit) A main exposure necessary irradiation dose calculation unit, a pre-exposure required irradiation time calculation unit, a main exposure necessary irradiation time calculation unit, a pre-exposure required current control unit, and a main exposure necessary irradiation time calculation unit.

  In the irradiation dose calculation unit 64, radiation X-ray dose data detected by the dose detection sensor 52 and breast thickness data with respect to the radiation transmission direction measured by the thickness measuring device 66 when the breast 44 is compressed by the compression plate 38. When the breast 44 is compressed with the compression plate 38, the compression pressure data measured by the pressure measuring device 68, the imaging condition data set by the operation setting unit 54, and the irradiation dose setting table storage unit 70 are stored. The data of the irradiation dose setting table thus prepared is supplied. The irradiation dose calculation unit 64 uses the irradiation dose setting table to select an irradiation dose necessary for pre-exposure and main exposure corresponding to a combination of dose, breast thickness, compression pressure, imaging conditions, etc., or irradiation The necessary irradiation dose is calculated by interpolating the data of the dose setting table and supplied to the radiation source control unit 56 and the grid control unit 62. The pre-exposure is a process of irradiating the breast 44 with a small amount of radiation X in order to calculate the irradiation dose of the radiation X necessary for obtaining a desired radiation image. In this process, the radiation 44 is irradiated to the breast 44 according to the irradiation dose calculated by the pre-exposure, and a radiation image is captured.

  The grid control unit 62 is supplied with the irradiation dose data calculated by the irradiation dose calculation unit 64 and the grid speed setting table data stored in the grid speed setting table storage unit 72. The grid control unit 62 selects the moving speed of the moving grid 23 in the pre-exposure and the main exposure corresponding to the irradiation time of the radiation X that can obtain a necessary irradiation dose using the grid speed setting table, or The moving speed is calculated by interpolating the data of the grid speed setting table and supplied to the grid driving unit 60.

  The mammography apparatus 20 of the present embodiment is basically configured as described above. Next, the operation will be described with reference to the flowchart shown in FIG.

  First, subject information, imaging conditions, an imaging method, and the like are set using the operation setting unit 54 of the mammography apparatus 20 (step S1). The subject information includes information such as the age, sex, body type, subject identification number, etc. of the subject 32, and can be obtained from an ID card or the like possessed by the subject 32. In addition, as imaging conditions, a tube current, a tube voltage, a target and filter type, a radiation X irradiation dose, and the like that can acquire an appropriate radiation image according to the breast 44 that is an imaging region of the subject 32 are set. The Further, the imaging method includes information such as an imaging part instructed by a doctor and an imaging direction. These pieces of information can be displayed and confirmed on the display operation unit 40 of the mammography apparatus 20. In addition, when the mammography apparatus 20 is connected to a network, it is also possible to acquire such information from a higher-level apparatus.

  Next, the radiologist sets the mammography apparatus 20 in a predetermined state according to the designated imaging method. For example, the imaging direction of the breast 44 is a head-to-tail direction (CC) imaging in which radiation X is irradiated from above, a side direction (ML) imaging in which radiation X is irradiated from the side, and from an oblique direction. There is an inside / outside oblique (MLO) imaging in which imaging is performed by irradiating radiation X, and the arm member 30 is pivoted about the pivot axis 28 in accordance with these imaging directions. FIG. 1 shows a case where head-to-tail (CC) imaging is performed.

  Next, the breast 44 of the subject 32 is positioned with respect to the mammography apparatus 20. That is, after the breast 44 is placed on the imaging stand 36, the compression plate 38 is moved toward the imaging stand 36, and the breast 44 is fixed between the imaging stand 36 and the compression plate 38 (see step S2, FIG. 2). .

  When the breast 44 is fixed between the imaging table 36 and the compression plate 38, the thickness measuring device 66 measures the thickness of the breast 44 with respect to the transmission direction of the radiation X, and supplies the data to the irradiation dose calculation unit 64 (step S3). ). Further, the pressure measuring device 68 measures the compression pressure of the breast 44 by the compression plate 38, and supplies the data to the irradiation dose calculation unit 64 (step S4).

  The irradiation dose calculation unit 64 reads the corresponding irradiation dose from the irradiation dose setting table storage unit 70 using the measured breast thickness and compression pressure data and the imaging conditions set by the operation setting unit 54, and performs pre-exposure. The pre-exposure necessary irradiation dose of the radiation X necessary for irradiation is calculated (step S5).

  For example, since the transmittance of the radiation X is high when the breast thickness is small, the dose detection sensor 52 can detect the radiation X transmitted through the breast 44 with high accuracy with a small irradiation dose. Further, when the compression pressure is low, the breast density of the breast 44 is low and the transmittance of the radiation X is considered high. Therefore, the dose detection sensor 52 similarly applies a small amount of radiation X transmitted through the breast 44. It can be detected with high accuracy by the dose. Furthermore, the dose of the radiation X reaching the dose detection sensor 52 depends on the radiation quality information including the imaging conditions such as the tube voltage set for the radiation source 22 and the type of target and filter.

  Therefore, for each combination of the compression thickness, the compression pressure, and the radiation quality information, the pre-exposure necessary irradiation dose that allows the dose detection sensor 52 to detect the radiation X dose with high accuracy is set as the irradiation dose setting table storage unit 70. The pre-exposure necessary irradiation dose corresponding to the input data is selected from the irradiation dose setting table storage unit 70. If the corresponding pre-exposure required irradiation dose is not stored in the irradiation dose setting table storage unit 70, the desired pre-exposure required irradiation dose is calculated by interpolating the existing pre-exposure required irradiation dose. That's fine. Also, instead of the irradiation dose setting table storage unit 70, a calculation formula using parameters such as breast thickness, compression pressure, and radiation quality information is set, and the pre-exposure required irradiation dose is calculated using this calculation formula. You may do it.

  The pre-exposure required irradiation dose calculated by the irradiation dose calculation unit 64 is supplied to the radiation source control unit 56 and the grid control unit 62, and the pre-exposure time during which the pre-exposure required irradiation dose can be obtained is calculated. (Step S6). The radiation X irradiation dose is determined by the product (mAs value) of the tube current (mA) of the radiation source 22 and the radiation X irradiation time (sec). Therefore, when the tube current is constant, the pre-exposure time can be easily calculated from the pre-exposure necessary irradiation dose.

  The grid control unit 62 calculates the moving speed of the moving grid 23 according to the calculated pre-exposure time (step S7). In this case, if the exposure time of the radiation X is short, the moving distance of the moving grid 23 during that time is shortened, so that the shadow of the moving grid 23 is formed in the radiation image captured by the solid state detector 24. Therefore, as shown in FIG. 6, the relationship between the exposure time t in which no shadow is formed and the moving speed v of the moving grid 23 is set in the grid speed setting table storage unit 72, and this grid speed setting is performed. Using the table, the moving speed of the moving grid 23 is determined.

  After the above processing is completed, the radiation source control unit 56 controls the radiation source 22 according to the calculated pre-exposure time, and performs pre-exposure that irradiates the breast 44 with the radiation X (step S8). In this case, the grid control unit 62 moves the moving grid 23 in the arrow C direction (FIG. 3) at the moving speed calculated in step S7 by the grid driving unit 60 together with the radiation X irradiation.

  The radiation X transmitted through the compression plate 38, the breast 44, the moving grid 23, and the solid state detector 24 enters the dose detection sensor 52, and the dose of the radiation X is detected (step S9). Data related to the dose detected by the dose detection sensor 52 is supplied to the irradiation dose calculation unit 64. The irradiation dose calculation unit 64 calculates the main exposure necessary irradiation dose necessary for the main exposure from the pre-exposure irradiation dose that is the dose of the radiation X detected during the pre-exposure time (step S10). In this case, since the breast 44 has already been irradiated with a predetermined amount of radiation X by pre-exposure, the pre-irradiation irradiation dose is subtracted to calculate the main exposure necessary irradiation dose.

  The main exposure necessary irradiation dose calculated by the irradiation dose calculating unit 64 is supplied to the radiation source control unit 56 and the grid control unit 62, and the main exposure time for obtaining the main irradiation necessary irradiation dose is calculated. (Step S11). Further, the grid control unit 62 calculates the moving speed of the moving grid 23 using the calculated main exposure time and the grid speed setting table stored in the grid speed setting table storage unit 72 (step S12).

  After the above processing is completed, the radiation source control unit 56 controls the radiation source 22 to perform main exposure to irradiate the breast 44 with the radiation X (step S13). In this case, the grid control unit 62 moves the moving grid 23 in the arrow C direction (FIG. 3) at the moving speed calculated in step S12 by the grid driving unit 60 together with the radiation X irradiation.

  The radiation X that has passed through the compression plate 38, the breast 44, and the moving grid 23 is applied to the solid state detector 24, and a radiation image is recorded as charge information. After the imaging of the breast 44 is completed, the reading light source 48 moves along the solid detector 24 in the direction of the arrow C (FIG. 3) and is irradiated with reading light, and the radiation image recorded on the solid detector 24 is read out. . The read radiation image is subjected to predetermined image processing by the image processing unit 58 (step S14).

  On the other hand, the solid state detector 24 from which the radiographic image has been read is irradiated with erasing light emitted from an erasing light source 50 to remove the accumulated unnecessary charges in order to perform the next imaging.

  7 and 8 show the relationship between the exposure time t of the radiation X and the tube current i supplied to the radiation source 22 in the above description. The pre-exposure range A and the main exposure range B indicated by the hatched portion are pre-exposed to the breast 44 as a reference with the tube current i1 and the pre-exposure time (t2-t1). This shows a case where after the necessary irradiation dose is set, the main exposure is performed with the tube current i1 and the main exposure time (t4-t3) to obtain an appropriate radiation image.

  On the other hand, for example, when the thickness of the breast 44 measured by the thickness measuring device 66 is smaller than the reference breast 44, the dose detection sensor 52 is short according to the thickness so that excessive radiation X is not irradiated. By setting the pre-exposure time (t5-t1) and detecting the dose of the radiation X, it is possible to calculate the irradiation dose required for this exposure with high accuracy (FIG. 7). In this case, since the thickness of the breast 44 is thin, the necessary main exposure time (t6-t3) is usually shortened. The moving speed of the moving grid 23 is adjusted according to each exposure time.

  Further, when the thickness of the breast 44 measured by the thickness measuring device 66 is larger than the reference breast 44, a long pre-exposure corresponding to the thickness is applied so that the radiation X that can be detected is irradiated to the dose detection sensor 52. By setting the time (t7-t1) and detecting the dose of the radiation X, the necessary exposure dose can be calculated with high accuracy (FIG. 8). In this case, since the thickness of the breast 44 is large, the necessary main exposure time (t8-t3) is usually long.

  9 and 10 are explanatory diagrams in the case where the tube current i is controlled instead of controlling the exposure time t in the pre-exposure of the radiation X. FIG. FIG. 11 is a relationship diagram between the irradiation dose Q of the radiation X necessary for detection by the dose detection sensor 52 or the solid state detector 24 and the tube current i from which the irradiation dose Q can be obtained.

  For example, when the thickness of the breast 44 is smaller than the reference breast 44, the tube current i1 is set to the tube current i2 (i1> i2) corresponding to the thickness of the breast 44 so that the pre-irradiation necessary irradiation dose can be obtained. Thus, by performing pre-exposure, the irradiation dose required for this exposure can be calculated with high accuracy (FIG. 9). Similarly, in the main exposure, the tube current can be adjusted according to the main exposure necessary irradiation dose.

  When the thickness of the breast 44 is larger than the reference breast 44, the tube current i1 is set to the tube current i3 (i3> i1) corresponding to the thickness of the breast 44, and the pre-exposure is performed. The necessary irradiation dose can be calculated with high accuracy (FIG. 10). Similarly, in the main exposure, the tube current can be adjusted according to the main exposure necessary irradiation dose.

  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, instead of the light readout type solid state detector 24, the present invention can also be applied to a radiation detector having a method of directly reading out charge information related to an accumulated radiation image as an electric signal, or a storage phosphor panel.

DESCRIPTION OF SYMBOLS 20 ... Mammography apparatus 22 ... Radiation source 23 ... Moving grid 24 ... Solid state detector 36 ... Imaging stand 38 ... Compression plate 44 ... Breast 52 ... Dose detection sensor 56 ... Radiation source control part 58 ... Image processing part 60 ... Grid drive part 62 ... Grid control unit 64 ... Irradiation dose calculation unit 66 ... Thickness measuring device 68 ... Pressure measurement device 70 ... Irradiation dose setting table storage unit 72 ... Grid speed setting table storage unit

Claims (6)

In a radiographic imaging apparatus that irradiates a breast with radiation output from a radiation source and detects a radiation image by detecting the radiation transmitted through the breast with a radiation detector,
A dose detection sensor for detecting a dose of the radiation transmitted through the breast;
A thickness measuring device for measuring a breast thickness with respect to a radiation transmission direction when the breast is pressed against the radiation detector by a compression plate;
Tube current setting means for setting a tube current to be supplied to the radiation source;
Pre-exposure required irradiation that calculates pre-exposure required irradiation time required for pre-exposure to irradiate the radiation to the breast prior to the main exposure for capturing the radiation image, using the measured breast thickness as a parameter A time calculator,
The main exposure required irradiation time required for the main exposure is calculated based on the pre-exposure irradiation dose based on the pre-exposure irradiation dose detected by the dose detection sensor. A necessary irradiation time calculation unit,
The radiation source is controlled according to the tube current and the pre-irradiation required irradiation time, and the pre-exposure is performed, while the radiation source is controlled according to the tube current and the main irradiation necessary irradiation time, and the main exposure is performed. A radiation source control unit for performing
A radiographic imaging device comprising: In a radiographic imaging apparatus that irradiates a breast with radiation output from a radiation source and detects a radiation image by detecting the radiation transmitted through the breast with a radiation detector,
A dose detection sensor for detecting a dose of the radiation transmitted through the breast;
A thickness measuring device for measuring a breast thickness with respect to a radiation transmission direction when the breast is pressed against the radiation detector by a compression plate;
Tube current setting means for setting a tube current to be supplied to the radiation source;
Prior to the main exposure for capturing the radiographic image, the pre-exposure required current, which is a tube current required for pre-exposure to irradiate the radiation to the breast, is measured with the measured breast thickness and predetermined pre-exposure required. A pre-exposure current control unit that controls based on the irradiation time;
Necessary for the main exposure based on the pre-exposure irradiation dose and the tube current set by the tube current setting means, with the dose at the pre-exposure detected by the dose detection sensor being a pre-exposure irradiation dose A main irradiation required irradiation time calculating unit for calculating a main irradiation required irradiation time,
The radiation source is controlled according to the pre-exposure required current and the pre-exposure required irradiation time and performs the pre-exposure, while the tube current setting means sets the tube current and the main exposure required irradiation time. A radiation source controller that controls the radiation source and performs the main exposure;
A radiographic imaging device comprising: The apparatus of claim 2.
The pre-exposure required current control unit makes the pre-exposure required current larger than the tube current set by the tube current setting means when the breast thickness is thicker than a predetermined threshold, while the breast When the thickness is smaller than the threshold, the radiographic imaging apparatus is characterized in that the pre-exposure required current is made smaller than the tube current set by the tube current setting means. The device according to any one of claims 1 to 3,
A moving grid that removes scattered radiation of the radiation applied to the radiation detector;
The moving speed of the moving grid is determined with reference to the calculated irradiation time in the pre-exposure or the main exposure and a grid speed setting table indicating a relationship between the irradiation time and the moving speed of the moving grid. A grid control unit that moves the moving grid at the determined moving speed;
A radiographic imaging apparatus, further comprising: In the apparatus of any one of Claims 1-4,
A pressure measuring device for measuring the compression pressure by the compression plate;
The pre-exposure required irradiation time calculation unit calculates the pre-exposure required irradiation time using the compression pressure as a parameter, or the pre-exposure required current control unit uses the compression pressure as a parameter. A radiographic imaging apparatus characterized by controlling a necessary current for irradiation. In the apparatus of any one of Claims 1-5,
The radiation image capturing apparatus, wherein the dose detection sensor is the radiation detector.

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