JP2011036392A - Radiation image capturing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a time from starting a pre-capturing till finishing a main capturing. <P>SOLUTION: In this radiation image capturing system 1, a control section 111, in the pre-capturing, allows a radiation image detector 107a to read not the whole two-dimensional region of a detection section 107a but a predetermined region, for example, a block region A or a block region B and to obtain a pre-captured image, allows the transmission of the image data of the obtained pre-captured image to a console 200, and allows the console to calculate the capturing conditions in the main capturing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic imaging system.

  2. Description of the Related Art Conventionally, in a radiographic imaging system, a radiographic image is obtained by irradiating a subject with a small amount of X-rays and transmitting through the subject before main imaging for imaging a diagnostic imaging image (referred to as a main imaging image). Pre-imaging that is read by a detector is performed, and X-ray irradiation conditions (tube voltage, tube current, irradiation time, etc.) at the time of main imaging are determined based on the X-ray dose obtained by pre-imaging ( For example, see Patent Document 1).

JP-A 63-500625

  By the way, in recent years, a radiographic technique for obtaining a radiographic image with excellent sharpness called phase contrast imaging has been used when mammography is performed. The phase contrast imaging is an enlargement imaging with respect to the standard imaging, and an edge-enhanced radiographic image by phase contrast is obtained using a small focus radiation source.

  In magnified imaging, a radiation image detector that accumulates and reads radiation transmitted through the subject is larger than that in standard imaging (no magnification), for example, 14 × 17 inches. Further, since mammography requires a high-accuracy image, it is preferably read with a pixel size smaller than that of other regions, for example, a high-definition pixel size of 30 μm to 100 μm. For this reason, the amount of data of the captured image obtained by enlarging the breast is very large.

  For example, when reading is performed using a radiation image detector having a gradation number of 12 bits, a pixel size of 43.75 μm, and a size of 14 × 17 inches, the amount of data when one pixel is 2 bytes of data is about 153 MB. It becomes. The effective speed of the wireless LAN is about 20 Mbps for IEEE802.11a / g, about 40 Mbps for IEEE802.11n, and about 100 Mbps for UWB. Therefore, when IEEE802.11a / g is used, it takes 30 seconds or more to transfer the data of the captured image read by the radiation image detector to the console for determining the X-ray irradiation amount at the time of actual imaging. It becomes. In addition, when the amount of data is large, it takes time to determine the X-ray irradiation conditions from the captured image obtained by pre-imaging.

  In mammography, pre-photographing to actual photographing are performed with the breast pressed. During this time, since the patient suffers from pressure, it is important how to shorten the time from pre-photographing to main photographing and perform photographing quickly. Even when imaging other parts, if the time from pre-imaging to main imaging is long, the subject may move, which is not preferable.

  An object of the present invention is to shorten the time from the start of pre-photographing to the end of main photographing.

In order to solve the above-mentioned problem, the invention described in claim 1
A radiation source for irradiating the subject with radiation;
A radiation detection element that outputs charges according to the amount of radiation that has passed through the subject has a detection unit that is arranged in a two-dimensional manner, and obtains a captured image of the subject by reading the charge generated by the detection unit A radiological image detector;
Control means for irradiating a predetermined amount of radiation from the radiation source in advance before the main photographing of the subject, and causing the radiological image detector to acquire a pre-photographed image for determining photographing conditions at the time of the main photographing;
A radiographic imaging system comprising:
The control means causes the radiographic image detector to read a predetermined area instead of the entire two-dimensional area during pre-imaging.

The invention according to claim 2 is the invention according to claim 1,
The control means controls the radiation field of the radiation source to be narrower at the time of pre-imaging than at the time of actual imaging, and causes the region corresponding to the radiation field of the radiation source in the detection unit to be read from the radiation image detector. .

The invention according to claim 3 is the invention according to claim 1,
When the subject is a breast, the control means determines a breast region based on an output from a pressure sensor provided on a compression plate for compressing the breast or a subject table for placing the breast. Detection is performed, and at the time of pre-imaging, a region corresponding to the detected breast region in the detection unit is read from the radiation image detector.

The invention according to claim 4 is the invention according to claim 1,
The control means causes the radiation image detector to read a region irradiated with radiation in the detection unit during pre-imaging.

The invention according to claim 5 is the invention according to claim 1,
The radiographic imaging system performs mammography,
The detection unit of the radiological image detector includes a plurality of regions,
The control means causes the region on the chest wall side of the detection unit to be read from the radiation image detector during pre-imaging.

The invention according to claim 6 is the invention according to any one of claims 1 to 5,
The control means causes the radiation image detector to perform reading at a predetermined line interval during pre-imaging.

The invention according to claim 7 is the invention according to any one of claims 1 to 6,
The radiographic image capturing system is a system that performs magnified photographing of the subject,
The control means performs control to bring the position of the radiation image detector into close contact with the subject during pre-imaging.

  According to the present invention, the time from the start of pre-photographing to the end of main photographing can be shortened.

It is a figure which shows the example of whole structure of the radiographic imaging system in this Embodiment. It is a figure for demonstrating the focus of the radiation source of FIG. It is a block diagram which shows the functional structure of the mammography apparatus of FIG. It is a figure for demonstrating the detection part of the radiographic image detector of FIG. It is a circuit block diagram of the radiographic image detector of FIG. FIG. 2 is a circuit block diagram for one pixel in the radiation image detector of FIG. 1. It is a block diagram which shows the functional structure of the console of FIG. It is a figure which shows the sequence of the expansion imaging process performed with a mammography apparatus and a console. (A) is a figure which shows the example by which the subject was arrange | positioned in either block area A and B, (b) is a figure which shows the example by which the subject was arrange | positioned ranging over block area A and B. . It is a figure for demonstrating the to-be-photographed object area | region and mammary gland area | region detected by S18 of FIG. It is a figure which shows the sequence of the expansion imaging process B performed by a mammography apparatus and a console. It is a figure which shows the sequence of the expansion imaging | photography process C performed with a mammography apparatus and a console.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, “X-ray” and “radiation” are treated synonymously.

<Embodiment 1>
(Configuration of radiation imaging system 1)
FIG. 1 is a diagram showing a system configuration of a radiographic imaging system 1 of the present invention.
As shown in FIG. 1, the radiographic image capturing system 1 includes a breast image capturing device 100 and a console 200. Data can be transmitted and received between the mammography apparatus 100 and the console 200.

(Configuration of breast image capturing apparatus 100)
First, the configuration of the mammography apparatus 100 will be described.
The breast image capturing apparatus 100 is an image capturing apparatus that performs radiation imaging using a breast as a subject H.
The mammography apparatus 100 is provided with a main body 103 that supports the radiation source 102. The main body 103 is provided with a subject table 104 that is movable in the irradiation direction of the radiation source 102 and supports the subject H, a support shaft 105 that hangs vertically with respect to the main body 103, and the like.

  Above the subject table 104, a compression plate 109 that compresses the subject H supported by the subject table 104 is supported by the main body 103 so as to be movable up and down. A pressure sensor 108 is provided on the surface of the compression plate 109 that contacts the subject H. The pressure sensor 108 may be provided on the subject table 104.

  A radiographic image detector 107 is provided below the subject table 104 so as to be movable up and down along the support shaft 105 based on the control of the control unit 111 (see FIG. 3).

  As the radiation source 102, an X-ray tube that emits X-rays having a radiation wavelength of about 0.1 to 1 mm is used. This X-ray tube emits X-rays by accelerating electrons generated by thermal excitation with a high voltage to collide with a cathode and converting the kinetic energy into radiant energy. When an X-ray image is taken, the acceleration voltage is set as a tube voltage, the amount of electrons generated as a tube current, and the X-ray emission time is set as an X-ray irradiation time. The anode (counter cathode) with which the electrons collide can change the radiated X-ray energy spectrum by changing the kind of copper, molybdenum, rhodium, tungsten or the like. When copper, molybdenum, rhodium, etc. are used as the anode, a relatively low energy line spectrum with a narrow X-ray energy distribution can be obtained, and mammography that interprets X-ray diffraction crystal analysis and fine structures using these characteristics. Used for. When tungsten is used as an anode, it is a broad spectrum, relatively high energy X-ray, which is used for human chest, abdomen, head, and general non-destructive inspection in industry. The medical or industrial use is characterized by a large X-ray dose. That is, it is common to use a rotating anode. Since the mammography apparatus 100 of the present embodiment is an apparatus used for medical purposes, an X-ray tube having a rotating anode of molybdenum, rhodium, or tungsten is preferable, and since it is an apparatus used for mammography purposes, Preferably it is molybdenum or rhodium.

As shown in FIG. 2, the X-ray tube includes a target T that generates X-rays when an electron beam generated by a cathode inside the X-ray tube collides with the X-ray tube. The size at which the electron beam collides with the target T is called the actual focus, and the substantial size viewed from the subject H side is called the effective focus. Here, the size of the effective focus is the focus size. In general, the shape of the effective focus is a square, and the length of one side is the focus size. When the shape of the focal point is a circle, the diameter is often indicated, and when the shape is a rectangle, the short side is often indicated. When the focal shape is a rectangle, the relationship between the focal point size of the real focal point and the effective focal point is as follows: the real focal point size (width: F _a , length: F _b ), the effective focal point size (width: F _A , long S: F _B ), if the target angle α, then F _A = F _a and F _B = F _b sin α.

  When the radiographic image detector 107 is brought into close contact with the object table 4 and X-ray imaging (close-contact imaging) is performed, the distance between the subject H and the radiographic image detector 107 becomes almost zero, and an image having only absorption contrast is obtained. can get.

  On the other hand, as disclosed in Japanese Patent No. 3,861,572, the distance between the X-ray tube and the subject table 104 and the distance between the radiation image detector 107 and the subject table 104 are set as a predetermined positional relationship as X. When line imaging is performed, phase contrast magnification imaging is performed, and an edge-enhanced (= phase contrast-enhanced) image caused by X-ray refraction can be obtained. X-rays are refracted when passing through the object, and the X-ray density inside the boundary of the object becomes sparse, and further, the outside of the subject H overlaps with X-rays that do not pass through the subject H, so that the X-ray density increases. In this way, the edge that is the boundary portion of the subject H is enhanced as an image. This is considered to be a phenomenon caused by a difference in refractive index with respect to X-ray between the subject H and air.

  However, in capturing a phase contrast image, a so-called penumbra occurs when the focal size of the X-ray is large. The penumbra is a phenomenon in which one point on the subject H is detected as an image having a size on the radiation image detector 107 due to the size of the focus size, and is a so-called blur. Therefore, unlike a synchrotron that emits monochromatic parallel X-rays or a micro-focus X-ray source that can be regarded as a point focus, an ordinary medical X-ray source has a finite focal size. Therefore, the influence of this penumbra becomes a problem.

  When the distance R2 between the subject H and the radiation image detector 107 is large, the blur width due to penumbra increases. For this reason, the lower limit value of the focal spot size is determined in order to obtain a certain amount of X-ray dose, and the object H and the radiation image detector 107 are obtained in order to obtain a sharp image by realizing the refraction contrast without penumbra blur. The upper limit of the focal spot size is determined from the distance R2 between the radiation source 102 and the distance R1 from the radiation source 102 to the subject H. If the focal spot size is too small, X-rays with sufficient intensity cannot be obtained, the imaging time becomes long, and the sharpness deteriorates due to blurring caused by the movement of the subject H. On the other hand, if the focal spot size is too large, blur due to penumbra dominates rather than edge enhancement by phase contrast, and sharpness decreases. Therefore, in order to perform phase contrast imaging in a normal medical facility, the focal spot size needs to be 30 μm or more and 250 μm or less, and preferably 50 μm or more and 100 μm or less.

In this embodiment, the radiation source 102 includes an X-ray tube having at least two focal points having different focal diameters, and the focal diameter is switched according to the setting of the X-ray irradiation conditions.
The focal points having different focal diameters are, for example, a focal point for close-contact photographing (referred to as a large focal point) and a focal point for phase contrast photographing (referred to as a small focal point) having a smaller focal diameter than that for close-contact photographing. The focal point for close-contact photography generally has a focal diameter of about 300 μm, and the focal point for phase contrast photography generally has a small focal diameter of about 100 μm. The focal diameter is determined by a standardized measurement method such as a slit method or a point source method. Standards include JIS Z4102, Z4704, IEC60336, etc., and any standard may be used.

  An irradiation field adjuster 106 (see FIG. 3) that varies the X-ray irradiation field is provided between the radiation source 102 and the subject table 104. This irradiation field adjuster 106 is provided with an X-ray limiter that prevents the X-ray from being irradiated outside the predetermined range of the irradiation field on the subject table 104 by, for example, changing the X-ray aperture. What was used is mentioned.

  The radiation image detector 107 is an FPD (Flat Panel Detector) that detects X-rays emitted from the radiation source 102 with a radiation detection element such as a photodiode and acquires the image as digital image data. In the present embodiment, the radiation image detector 107 includes a scintillator and the like, and will be described as a so-called indirect FPD that obtains an electric signal by converting emitted X-rays into electromagnetic waves of other wavelengths such as visible light. A so-called direct type FPD that directly detects X-rays with a radiation detection element without using a scintillator or the like may be used. Details of the radiation image detector 107 will be described later.

  The housing 110 is provided with a control unit 111, an operation unit 112, a display unit 113, a communication unit 114, a power supply unit 117, and the like illustrated in FIG.

  As shown in FIG. 3, the control unit 111 includes a radiation source 102, an irradiation field adjuster 106, a reading control unit 22, a pressure sensor 108, an operation unit 112, a display unit 113, a communication unit 114, a driving device 115, and position detection. The unit 116 and the power source unit 117 are connected via a bus 118 to centrally control the operation of each unit.

  The control unit 111 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ROM of the control unit 111 stores a control program for controlling each part of the mammography apparatus 100 and various processing programs. The CPU cooperates with these control programs and each part of the mammography apparatus 100. Overall control of the operation.

  In the present embodiment, the control unit 111 executes enlargement photographing processing, performs pre-photographing for determining photographing conditions at the time of main photographing before the main photographing of the subject H, and pre-photographed images acquired by pre-photographing. The main shooting is performed according to the shooting conditions transmitted from the console 200 based on the image data.

The operation unit 112 includes an X-ray irradiation switch for instructing X-ray irradiation, a keyboard, a touch panel, and the like for inputting patient information, an imaging direction, an enlargement ratio at the time of enlargement imaging, and the like. A key pressing signal and a mouse operation signal that have been pressed are output to the control unit 111 as input signals. The operation unit 112 includes an operation mechanism for adjusting the positions of the subject table 104 and the compression plate 109.
The display unit 113 includes a monitor such as an LCD (Liquid Crystal Display) and displays various screens in accordance with instructions of a display signal input from the control unit 111.

  The communication unit 114 includes a LAN (Local Area Network) card or the like, and performs data transmission / reception with the console 200 via a communication network N such as a LAN.

  The driving device 115 includes a motor that rotates the main body 103 in accordance with a control signal input from the control unit 111, a motor that moves the radiographic image detector 107 up and down in accordance with a control signal input from the control unit 111, and the like.

  The position detection unit 116 detects the position of the subject table 104 and the position of the compression plate 109 and outputs the detected position to the control unit 111. The position detection unit 116 may employ a method using photometry using infrared rays, a method in which a line resistance is provided on the rail of the support shaft that slides the subject table 104 or the compression plate 109, and the position is determined based on the resistance value measurement.

(Configuration of radiation image detector 107)
Hereinafter, the radiation image detector 107 will be described with reference to FIGS. 4 is a diagram showing a reading area of the radiation image detector 107, FIG. 5 is a circuit block diagram of the radiation image detector 107, and FIG. 6 is a circuit block diagram of one pixel in the radiation image detector 107.

As shown in FIG. 5, the radiation image detector 107 includes a detection unit 107 a in which a plurality of radiation detection elements 7 are two-dimensionally arranged. As shown in FIG. 4, the detection unit 107a includes two reading areas (hereinafter referred to as block areas) A and B.
Each radiation detection element 7 is constituted by, for example, a photodiode or the like, and the amount of electromagnetic waves (scintillator) output by converting X-rays incident from the radiation incident surface R by a scintillator (not shown) in the radiation image detector 107. The amount of electric charge (signal amount) that is finally accumulated differs depending on the dose of X-rays incident on. In addition to this, for example, a phototransistor or the like can be used as the radiation detection element 7.

  Each radiation detection element 7 disposed in the block region A has a second electrode 78 (see FIG. 6) connected to the bias line 9A and the connection 10A, respectively. Each radiation detection element 7 disposed in the block region B has a second electrode 78 connected to the bias line 9B and the connection 10B, respectively. Each connection 10A, 10B is connected to a reverse bias power supply 14.

  The reverse bias power source 14 is connected to the reading control unit 22, and in accordance with the control from the reading control unit 22, the reverse bias is applied to each radiation detection element 7 via the connection lines 10A and 10B and the bias lines 9A and 9B. A voltage is applied.

  The current detection means 42A and the current detection means 42B are provided on the connections 10A and 10B of the bias lines 9A and 9B, respectively. The current detection means 42 </ b> A and 42 </ b> B are connected to the reading control unit 22.

  The current detection means 42A and 42B independently detect the current flowing in the connection 10A in which the bias lines 9A are bundled and the current flowing in the connection 10B in which the bias lines 9B are bundled. Specifically, although not shown, the current detection means 42A and 42B measure a voltage between a resistor having a predetermined resistance value connected in series to the connection lines 10A and 10B, and both terminals of the resistor, respectively. And a differential amplifier. Then, by measuring the voltage between the two terminals of the resistor with a differential amplifier, the current flowing through the connections 10A, 10B is detected by converting it to a voltage value, and the voltage value corresponding to the current value flowing through each of the connections 10A, 10B Are output to the reading control unit 22, respectively.

  The first electrode 74 of each radiation detection element 7 is connected to the source electrode 8 s (denoted as S in FIGS. 5 and 6) of the TFT 8. A gate electrode 8 g (denoted as G in FIGS. 5 and 6) of each TFT 8 is connected to each scanning line 5 extending from the scanning drive circuit 15. A drain electrode 8d (denoted as D in FIGS. 5 and 6) of each TFT 8 is connected to each signal line 6.

When a reverse bias voltage is applied to the second electrode 78 of the radiation detection element 7 via the bias lines 9 </ b> A and 9 </ b> B by the reverse bias power supply 14, an electrical gradient is generated in the radiation detection element 7. When X-rays are irradiated from the radiation source 102 in this state, and the X-rays are converted into electromagnetic waves by a scintillator (not shown) and enter the radiation detection element 7, the radiation detection element 7 is proportional to the number of photons of the incident electromagnetic waves. As a result, electron-hole pairs are generated.
Among the generated electron-hole pairs, electrons move to the first electrode 74 side (see FIG. 6), which has a high potential, according to the potential gradient. When the gate of the TFT 8 is closed, the generated electrons are accumulated in the vicinity of the first electrode 74.
On the other hand, of the generated electron-hole pairs, the holes move to the second electrode 78 having a low potential according to the potential gradient, pass through the second electrode 78 to the connections 10A and 10B via the bias lines 9A and 9B. Flows out. Holes flowing through the connection 10 </ b> A are detected as current by the current detection means 42 </ b> A, and a voltage value corresponding to the current is output to the reading control unit 22. Holes flowing through the connection 10 </ b> B are detected as current by the current detection unit 42 </ b> B, and a voltage value corresponding to the current is output to the reading control unit 22.

  When the voltage value output from the current detection unit 42A exceeds a predetermined threshold value, the reading control unit 22 detects that the block region A has been irradiated with X-rays. Further, when the voltage value from the current detection unit 42B exceeds a predetermined threshold value, the reading control unit 22 detects that the block region B has been irradiated with X-rays. Then, the reading control unit 22 applies a signal reading voltage from the scan driving circuit 15 to the gate electrode 8 g of the TFT 8 via the scanning line 5.

  When a signal reading voltage is applied from the scanning drive circuit 15 to the gate electrode 8 g of the TFT 8 through the scanning line 5 by the control from the reading control unit 22, the gate of the TFT 8 is opened and accumulated in the radiation detection element 7. The charged charge, that is, an electric signal is read from the drain electrode 8d to the signal line 6 through the source electrode 8s of the TFT 8. Each signal line 6 in the block area A is connected to the readout circuit 17A. Each signal line 6 in the block region B is connected to the readout circuit 17B.

As shown in FIG. 5, the readout circuits 17A and 17B are composed of an amplifier circuit 18, a correlated double sampling circuit 19, an analog multiplexer 20, and an A / D converter 21, The charges read from the radiation detection elements 7 through the signal lines 6 are converted into electric signals by performing charge voltage conversion and amplification etc. for each radiation detection element 7.
In FIGS. 5 and 6, the correlated double sampling circuit is expressed as CDS. In FIG. 6, the analog multiplexer 20 is omitted.

The amplifier circuit 18 is constituted by, for example, a charge amplifier circuit, and is constituted by connecting an operational amplifier 18a, capacitors C1 to C2 and a charge reset switch SW1 in parallel with the operational amplifier 18a. A switch SW2 is connected in series to the capacitor C2, and on / off of the charge reset switch SW1 and the switch SW2 is controlled by the read control unit 22.
The signal line 6 is connected to the inverting input terminal 18a1 on the input side of the operational amplifier 18a of the amplifier circuit 18, and the non-inverting input terminal 18a2 on the input side of the amplifier circuit 18 is grounded (GND). That is, this embodiment corresponds to the case where the initial voltage is set to 0 [V].

  Hereinafter, the case where the non-inverting input terminal 18a2 on the input side of the amplifier circuit 18 is grounded as described above will be described. However, a predetermined initial voltage is applied to the non-inverting input terminal 18a2 on the input side of the amplifier circuit 18. It is also possible to configure as described above.

  In the amplifier circuit 18, when the gate of the TFT 8 of the radiation detection element 7 is opened with the charge reset switch SW1 turned off (that is, when a signal readout voltage is applied to the gate electrode 8g of the TFT 8), the capacitor C1 The charges read from the radiation detection element 7 are accumulated in the capacitors C1 and C2 when the switch SW2 is turned on, and a voltage value corresponding to the accumulated charge amount is output from the output terminal 18a3 of the operational amplifier 18a. It is output. In this way, the amplification circuit 18 outputs a voltage value according to the amount of charge output from each radiation detection element 7 and amplifies the voltage by voltage conversion.

In the present embodiment, capacitors having capacitances of 0.5 pF and 0.5 pF are used as the capacitors C1 and C2, respectively, and the capacitance of the capacitors C1 and C2 as a whole is controlled by turning on / off the switch SW2 under the control of the reading control unit 22. Can be set in two stages of 0.5 pF or 1 pF. When the switch SW2 is turned off, the gain can be largely adjusted.
On the other hand, when the charge reset switch 18c is turned on by the control from the reading control unit 22, the input side and the output side of the amplifier circuit 18 are short-circuited, and the charge accumulated in the capacitor 18b is discharged and amplified. Circuit 18 is reset.
It should be noted that the range width of the capacitance set for the entire capacitor in the amplifier circuit 18 and the capacitance to be set are appropriately set according to the performance required for the radiation image detector 107, and the capacitance of each capacitor for realizing it. Etc. are also determined as appropriate.

  A correlated double sampling circuit 19 is connected to the output side of the amplifier circuit 18. The correlated double sampling in the correlated double sampling circuit 19 is performed as follows.

  In the radiation image detector 107, the capacitors C1 and C2 are turned on and the charge reset switch SW1 is turned on before the gate of the TFT 8 of each radiation detection element 7 is opened for signal readout. A so-called reset is performed to release the charges accumulated in the capacitors C1 and C2. Thereafter, the charge reset switch SW1 is turned off, and a signal reading standby state is set. The correlated double sampling circuit 19 first holds the voltage value output from the output side terminal of the amplifier circuit 19 at that stage. In addition, the gates of the TFTs 8 of the radiation detection elements 7 are opened, electric signals are read from the radiation detection elements 7, charges are accumulated in the capacitors C1 and / or C2 of the amplifier circuit 18, and then the gates of the TFTs 8 are closed. At this stage, the correlated double sampling circuit 19 again holds the voltage value output from the output side terminal of the amplifier circuit 18. The correlated double sampling circuit 19 calculates the difference between the two voltage values held in this way and outputs an analog value of the electrical signal from the radiation detection element 7. In this way, the correlated double sampling circuit 19 reduces noise when the capacitor is reset.

  The electric signal output from the correlated double sampling circuit 19 is sequentially transmitted to the A / D converter 21 via the analog multiplexer 20 and converted into a digital value by the A / D converter 21. The A / D converter 21 sequentially outputs the electrical signal of each radiation detection element 7 converted into a digital value to the reading control unit 22.

  Here, the block areas A and B are individually switched to the reading mode or the standby mode according to the control of the reading control unit 22. In the reading mode, power is supplied from the power supply unit 117 to the reading circuits 17A and 17B under the control of the reading control unit 22, and the charge amplifier circuit constituting the amplifier circuit 18 is put into an operating state. On the other hand, in the standby mode, the read circuits 17A and 17B themselves are not energized, and the charge amplifier circuit that constitutes the amplifier circuit 18 is inactivated.

  When the charge amplifier circuit constituting the amplifier circuit 18 is deactivated, a current flows between the inverting input terminal 18a1 and the non-inverting input terminal 18a2 (see FIG. 6) on the input side of the operational amplifier 18a of the amplifier circuit 18. Disappear. Therefore, since the loop electrically connected to ground (GND) → reverse bias power supply 14 → (current detection means 42A (42B)) → radiation detection element 7 → TFT 8 → signal line 6 is broken at the operational amplifier 18a, radiation detection is performed. A closed loop including the element 7 and the reverse bias power source 14 cannot be formed.

  Therefore, in this embodiment, as shown in FIG. 6, each operational amplifier 18a of the amplifier circuit 18 of the readout circuit 17A (17B) is grounded to the inverting input terminal 18a1 to which the signal line 6 is connected as described above. A mode changeover switch 24 that is connected to the non-inverting input terminal 18a2 and switches between short-circuit and cancellation of the short-circuit is provided on the upstream side of each operational amplifier 18a.

  In this embodiment, the mode changeover switch 24 is composed of a MOSFET (MOS field effect transistor). A gate electrode (not shown) of the MOSFET, which is the mode switching switch 24, is connected to the reading control unit 22, and the mode switching is performed by switching the application of the voltage from the reading control unit 22 to the gate electrode and stopping of the application. The on / off state of the switch 24 is controlled.

  When the reading circuit 17A (17B) is set to the standby mode, the reading control unit 22 does not energize the reading circuit 17A (17B), sets the charge amplifier circuit constituting the amplifier circuit 18 in a non-operating state, The mode changeover switch 24 is turned on to short-circuit the inverting input terminal 18a1 and the non-inverting input terminal 18a2 of each operational amplifier 18a of the amplifier circuit 18 of the readout circuit 17A (17B).

  Thus, when each mode changeover switch 24 is turned on, as shown in FIG. 6, even if the charge amplifier circuit constituting the amplifier circuit 18 is in the non-operating state, ground (GND) → reverse bias power supply A closed loop of 14 → (current detection means 42) → image sensor 7 → TFT 8 → mode changeover switch 24 → ground (GND) is formed.

  Further, when the reading circuit 17A (17B) is set to the reading mode described above, the reading circuit 17A (17B) is energized, the charge amplifier circuit constituting the amplifier circuit 18 is set in the operating state, and the mode changeover switch is set. 24 is turned off.

  Image data output from the readout circuits 17A and 17B is stored in the RAM in the reading control unit 22, and is output to the console 200 via the wireless communication unit 29 in the radiation image detector 107.

(Console 200 configuration)
Next, the configuration of the console 200 will be described.
The console 200 receives image data of a pre-photographed image acquired by pre-photographing from the mammography apparatus 100, and calculates a photographing condition for the main exposure based on the received image data. Further, the image data of the actual captured image acquired by the actual imaging is received from the breast image capturing apparatus 100, and the received image data is subjected to image processing and displayed.

  FIG. 7 is a block diagram showing a functional configuration of the console 200. As shown in FIG. 7, the console 200 includes a control unit 211, an operation unit 212, a display unit 213, a storage unit 214, a wireless communication unit 215, and a communication unit 216, and each unit is connected via a bus 217. ing.

  The control unit 211 includes a CPU, a ROM, and a RAM. The ROM of the control unit 211 stores a control program for controlling each part of the console 200 and various processing programs, and the CPU controls the operation of each part of the console 200 in cooperation with these control programs. Control.

  The operation unit 212 includes a keyboard having cursor keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse, and controls an instruction signal input by key operation or mouse operation on the keyboard. 211 is output. The operation unit 212 may include a touch panel on the display screen of the display unit 213, and in this case, an instruction signal input via the touch panel is output to the control unit 211.

  The display unit 213 is configured by a monitor such as an LCD or a CRT (Cathode Ray Tube), and displays an input instruction, data, and the like from the operation unit 212 in accordance with an instruction of a display signal input from the control unit 211.

  The storage unit 214 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 214 stores image data transmitted from the mammography apparatus 100 and subjected to image processing.

  The wireless communication unit 215 includes a wireless LAN card or the like, and performs data transmission / reception with the radiation image detector 107 wirelessly.

  The communication unit 216 is configured by a LAN card or the like, and performs data transmission / reception with the mammography apparatus 100 via the communication network N.

(Operation of Radiation Imaging System 1)
Next, operation | movement of the radiographic imaging system 1 is demonstrated.
FIG. 8 is a diagram illustrating a flow of enlargement imaging processing executed by the mammography apparatus 100 and the console 200 when an instruction for enlargement imaging is input from the operation unit 112 or the operation unit 212. The process on the mammography apparatus 100 side shown in FIG. 8 is executed under the control of the control unit 111, and the process on the console 200 side is executed under the control of the control unit 211.

  In the breast image photographing apparatus 100, when a photographing direction and an enlargement ratio are input by the operation unit 112 (step S1), the driving unit 115 is controlled by the control unit 111 based on the input photographing direction, and The rotation is controlled (step S2). For example, when the input photographing direction is MLO for photographing the breast from the oblique direction, the driving unit 115 rotates the main body 103 by a predetermined amount so as to be inclined.

  Next, the position of the subject table 104 is adjusted in the vertical direction according to the operation of the operation unit 112 in consideration of the height of the subject by an engineer or the like (step S3), and the position of the compression plate 109 is adjusted by the operation of the operation unit 112. When the subject H is pressed and fixed (step S4), pre-shooting shooting conditions are set by the control unit 111 (step S5). In step S5, for example, the breast thickness of the subject H is calculated based on the position of the compression plate 109 and the position of the subject table 104 output from the position detection unit 116. Then, the imaging condition corresponding to the calculated breast thickness is read from the table stored in the ROM of the control unit 111, and the imaging condition is set. The imaging conditions are mainly X-ray irradiation conditions, such as tube voltage of the radiation source 102, tube current, filter presence / absence, X-ray irradiation time, and the like. Note that the pre-photographing is photographing for determining photographing conditions for the main photographing, and is not used for diagnostic interpretation. Therefore, in order to suppress the exposure amount of the subject H, the image is captured with a smaller dose than in the main imaging.

  Next, the pre-imaging reading condition is transmitted to the reading control unit 22 by the control unit 111, and the pre-imaging reading condition is set to the radiation image detector 107 (step S6). Specifically, when the switch SW2 of each pixel of the radiation image detector 107 is set to OFF, the reading gain is set to be larger. This is to make it easier to analyze the histogram when calculating the photographing condition by increasing the density (signal value) resolution of the pre-photographed image. Next, the irradiation field adjuster 106 is controlled in accordance with the operation of the photographer, and the irradiation field on the radiation image detector 107 is adjusted (step S7).

  When the X-ray irradiation switch (first stage) of the operation unit 112 is pressed (step S8; YES), the control unit 111 transmits a first reset start signal to the reading control unit 22 of the radiation image detector 107, Reset (first reset) is performed in the radiation image detector 107 (step S9). In the radiation image detector 107, when the first reset start signal is received, the mode switch 24 is turned on under the control of the reading control unit 22, and each radiation detection element 7 is connected from the reverse bias power supply 14. A reverse bias voltage is applied to. Next, the charge reset switches SW1 and SW2 of all the amplifier circuits 18 are turned on. In addition, a voltage for signal readout is applied from each scanning drive circuit 15 to the gate electrodes 8g of the TFTs 8 of all the radiation detection elements 7 via the scanning lines 5, and all the TFTs 8 are turned on. By this reset, excess charges accumulated in the radiation detection element 7 and the capacitors C1 and C2 can be discharged to the bias lines 9A and 9B.

  When the predetermined time elapses, the control unit 111 transmits a first reset stop signal to the reading control unit 22, and the radiation image detector 107 shifts to the accumulation state (step S10). In the radiation image detector 107, when the first reset stop signal is received, the charge reset switch SW1 and the switch SW2 are turned off under the control of the reading control unit 22. Further, when the off voltage is applied to the gate voltage 8g of all the TFTs 8 and all the TFTs 8 are turned off, the storage state is entered.

  Further, the irradiation field adjuster 106 is controlled by the control unit 111, and the irradiation field is narrowed to the reading area in the subsequent step S14 (step S11).

  When the X-ray irradiation switch (second stage) of the operation unit 112 is pressed (step S12; YES), the radiation source 102 is controlled by the control unit 111 based on the imaging conditions set in step S5, and the focal point is large. Is used for pre-irradiation (X-ray irradiation in pre-imaging) with a small dose (step S13). In mammography, since the breast is pressed from pre-photographing to main-photographing, photographing is performed with a large focus in order to shorten the pre-photographing time as much as possible. In the radiation image detector 107, charges corresponding to the X-ray dose transmitted through the subject H are accumulated in each radiation detection element 7.

  When the pre-imaging is completed, the first reading control signal is transmitted from the control unit 111 to the reading control unit 22, and the pre-photographed image is read by the radiation image detector 107 (step S14).

  Here, the detection unit 107a (block region A + B) of the radiation image detector 107 is designed to be sufficiently large (for example, 14 × 17 inches) with respect to the size of the subject H. Therefore, the radiographic image detector 107 does not read the entire block areas A and B, but reads only the area where the X-ray charges that have passed through the subject H are accumulated in the pre-photographing process. The amount of data can be reduced.

  Therefore, in the present embodiment, the reading control unit 22 determines the reading area (the area to be read) and the reading interval (how many lines (scanning line) are read) in the detection unit 107a by the first reading control signal. By instructing, the data amount of the pre-captured image is reduced.

For example, as shown in FIG. 9A, in the case where the radiation image detector 107 is arranged so that the block region B is on the chest wall side, the image of the subject H is usually within the block region B. Therefore, when the radiation image detector 107 is arranged so that the block region B is on the chest wall side, the reading control unit 22 is instructed to read the block region B by the first reading control signal. In this way, by reading only the block region B, the data amount of the pre-captured image can be suppressed to ½ of the data amount when the entire radiation image detector 107 is read. In addition, the reading control unit 22 may be instructed not only by the reading area (the area to be read) but also by the first reading control signal. For example, if reading is performed every other line, the data amount of the pre-captured image can be reduced to ¼.
Note that it is preferable that an instruction to read the entire area of the detection unit 107a can be input in advance by the operation unit 112 according to the size of the subject H.

In addition, when imaging in the CC imaging direction in which the breast is imaged in the vertical direction, it is known that the tissue distribution in the breast is substantially symmetrical. Therefore, as shown in FIG. 9B, when the subject H, that is, the left side (or right side) of the breast is arranged in the block region A, and the right side (or left side) of the subject H is arranged in the block region B, the block region A Alternatively, the density histogram distribution of the image obtained by reading one of the regions B and the other image is substantially the same. Therefore, in step S14, as shown in FIG. 9B, when the radiographic image detector 107 is arranged so that the imaging direction is CC and the subject H extends over the block areas A and B, the first is performed. This reading control signal instructs the reading control unit 22 to read only one of the block areas A and B. As described above, by reading only one of the block areas A and B, the data amount of the pre-captured image is suppressed to ½ of the data amount when the entire radiation image detector 107 is read. Can do. Further, the reading control unit 22 may be instructed not only by the reading area but also by the first reading control signal. For example, if reading is performed every other line, the data amount of the pre-captured image can be reduced to ¼.
In the arrangement shown in FIG. 9B, if the block area to be read is divided in half in the direction parallel to the reading scanning direction and only the area located in the chest wall side area is read, pre-imaging This is preferable because the amount of image data can be further reduced.

Note that the reading interval is not limited to every other line, and for example, the reading interval may be controlled so as to increase from the chest wall side useful for calculation of imaging conditions toward the opposite side (so that the thinning rate increases). Good. For example, the reading interval is 2 ⁿ (n is an integer greater than or equal to zero) in order from the chest wall side. In this way, the data amount of the pre-photographed image can be further reduced.

  In the radiation image detector 107, when the first reading control signal is received, the mode changeover switch 24 of the block area designated as the reading area is turned on by the control of the reading control unit 22, The block area reading circuit (17A or 17B) designated as the reading area is energized, and the on-voltage is applied to the gate voltage 8g of the TFT 8 by the scanning drive circuit 15 at the designated reading interval. The TFT 8 is turned on. Then, the charge stored in the radiation detection element 7 in the designated block region is read and converted into a digital image, whereby a pre-captured image is read.

  When the reading of the pre-photographed image is completed, the control unit 111 transmits a second reset start signal to the reading control unit 22, and the radiation image detector 107 performs a reset (second reset) (step S15). In the reading control unit 22, the image data of the pre-captured image is transmitted to the console 200 by the wireless communication unit 29 (step S16). Further, the irradiation field adjuster 106 is controlled by the control unit 111, the irradiation field is returned to the region set by the photographer in step S7, and the driving device 115 is controlled in accordance with the enlargement factor input in step S1. The position of the radiation image detector 107 is moved (step S17).

  In the console 200, when the image data of the pre-captured image is received by the wireless communication unit 215, the control unit 211 analyzes the pre-captured image (step S18).

In step S18, the subject region and the mammary gland region are detected from the pre-photographed image. The following processing can be used as a method for detecting the subject area (breast area) and the mammary gland area.
In the detection of the subject region, first, a differential filter such as pre-witt is applied to the pre-photographed image in the nipple-chest wall direction X (the short axis direction of the image) shown in FIG. The position within the range is set as a skinline candidate point. Skin line candidate points are obtained for all rows in the long axis direction Y of the image, and a line connecting the skin line candidate points is detected as a skin line Sa. Then, an area between the detected skin line Sa and the chest wall is detected as a subject area Ha.
In the detection of the mammary gland region, first, a local region is set in the detected subject region Ha, and the local region is binarized with a threshold value determined from the pixel signal value in the local region. As the threshold value, a value obtained by subtracting a certain amount from the average value of the pixel signal values in the local region or a value multiplied by a coefficient less than 1 is used. A local area is set for each predetermined interval in the subject area Ha, threshold value determination and binarization are repeated for each local area, and an area having a smaller pixel signal value than the threshold is extracted from the obtained binarized image. To do. Thereby, first, a low signal region including the mammary gland region Hb and the pectoral muscle region Hc is extracted. Next, in the above-mentioned image obtained by applying a differential filter such as prewitt to the pre-photographed image, an edge row along a diagonal line between the skin line Sa and the chest wall is detected as a pectoral muscle line Hd, A region surrounded by the pectoral muscle line Hd and the chest wall is recognized as a pectoral muscle region Hc. Then, the breast region Hb is detected by removing the pectoral muscle region Hc from the low signal region.

Next, in the control unit 211, the photographing conditions for the main photographing are calculated based on the analysis result (step S19).
In step S19, for example, a histogram of the pixel signal value of the mammary gland region Hb detected in step S17 is created, and a pixel signal value having a predetermined ratio of the cumulative frequency from the minimum value is calculated. Then, the X-ray irradiation time in the main imaging is calculated from the calculated pixel signal value, the pre-imaging X-ray irradiation time, and the pixel signal value desired for the pixel signal value calculated in the main imaging image. The X-ray irradiation time at the time of pre-imaging is acquired from the mammography apparatus 100. When the calculated X-ray irradiation time is longer than a predetermined value, imaging is performed so that imaging is performed with a higher tube voltage, a filter that transmits higher energy X-rays, and an anode that emits X-rays with higher energy distribution. Change the condition. At that time, the X-ray irradiation time is calculated so that the calculated pixel signal value becomes a desired value in the changed X-ray irradiation.

  The calculated imaging conditions are transmitted to the mammography apparatus 100 by the communication unit 216. Information on the detected subject area Ha is also transmitted (step S20).

  In the mammography apparatus 100, when the imaging condition is received by the communication unit 114, the imaging condition received by the control unit 111 is set (step S21). Further, the control unit 111 transmits a second reset stop signal and a control signal for setting a smaller gain to the reading control unit 22 (step S22). In the radiation image detector 107, when the second reset stop signal is received, the second reset is stopped by turning off the charge reset switch SW1 and the switch SW2 under the control of the reading control unit 22. Is stored. When the control signal for setting the smaller gain is received, the switch SW2 is turned on.

  Then, the radiation source 102 is controlled by the control unit 111, and main irradiation (X-ray irradiation in main imaging) is performed using the small focal point under the set imaging conditions (step S23).

When the main imaging is finished, a second reading control signal is transmitted from the control unit 111 to the reading control unit 22, and the radiographic image detector 107 reads the main shooting image (step S24). In step S24, the entire area of the detection unit 107a, that is, the entire area of the block areas A and B is designated as the reading area. In the radiation image detector 107, when the second reading control signal is received, the reading circuits 17A and 17B are energized under the control of the reading controller 22, and the gate voltage 8g of each TFT 8 is supplied by the scanning drive circuit 15. The on-voltage is applied to all the TFTs 8, and all the TFTs 8 are turned on. Then, the electric charge accumulated in each radiation detection element 7 is read and digitally converted, whereby the image data of the actual captured image is read.
Even in the main imaging, only the irradiation field area, not the entire area of the detection unit 107a, may be set as the reading area. Alternatively, only the area corresponding to the subject area Ha detected from the pre-photographed image may be read.

  When the reading of the main captured image is completed, the image data of the main captured image is transmitted to the console 200 by the wireless communication unit 29 of the radiation image detector 107 (step S25). Further, the driving device 115 is controlled, and the position of the radiation image detector 107 is moved to a position in close contact with the subject table 104 (step S26). This is for the next shooting.

  In the console 200, when the image data of the actual captured image is received by the wireless communication unit 215, the control unit 211 performs image processing such as gradation processing, frequency enhancement processing, dynamic range compression processing, and the like (step S27). . Then, the processed image data is displayed on the display unit 213 (step S28), and this process ends.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described. Since the configuration of the second embodiment is the same as the configuration of the first embodiment, the description will be used and the operation of the second embodiment will be described below.
FIG. 11 is a diagram illustrating a flow of the enlargement imaging process B executed by the breast image capturing apparatus 100 and the console 200 in the second embodiment. The processing on the mammography apparatus 100 side shown in FIG. 11 is executed under the control of the control unit 111, and the processing on the console 200 side is executed under the control of the control unit 211.

  The enlarged photographing process B in FIG. 11 includes the step S4-2 added between the steps S4 and S5 of the enlarged photographing process in FIG. 8 described in the first embodiment, the specific processing contents of the step S14, and The difference is that the process of step S11 is omitted. Hereinafter, the operation of the second embodiment will be described with respect to parts different from the first embodiment.

In step S4, when the photographer adjusts the position of the compression plate 109 and the subject H is pressed and fixed, in step S4-2, the subject region is detected by the pressure sensor 108 and output to the control unit 111. .
In step S14, the subject area detected in step S4-2 is instructed as a reading area by the control unit 111 to the reading control unit 22 by the first reading control signal. Specifically, a block area and a reading line to be read are instructed based on the detected subject area. Also, reading intervals such as every other line are instructed. The radiation image detector 107 reads a region designated as a reading target and obtains a pre-photographed image. The reading interval is not limited to every other line, and for example, the reading interval may be controlled to increase from the chest wall side useful for calculation of imaging conditions toward the opposite side. For example, the reading interval is set to 2 ^{n in} order from the chest wall side. In this way, the data amount of the pre-photographed image can be further reduced.
In step S24, only the area corresponding to the subject area detected by the pressure sensor 108 may be set as the reading area, as in the pre-shooting, not the entire area of the detection unit 107a. Alternatively, the subject area Ha detected from the pre-photographed image may be acquired from the console 200, and the area corresponding to the subject area Ha may be read. In this way, the data amount of the actual captured image can be reduced.

<Embodiment 3>
Next, a third embodiment of the present invention will be described. Since the configuration of the third embodiment is the same as the configuration of the first embodiment, the description will be referred to and the operation of the third embodiment will be described below.
FIG. 12 is a diagram illustrating a flow of the enlargement imaging process C executed by the breast image capturing apparatus 100 and the console 200 in the third embodiment. The process on the mammography apparatus 100 side shown in FIG. 12 is executed under the control of the control unit 111, and the process on the console 200 side is executed under the control of the control unit 211.

  The enlarged photographing process C in FIG. 12 includes the point that the process in step S13-2 is added between steps S13 and S14 in the enlarged photographing process in FIG. 8 described in the first embodiment, the specific processing contents in step S14, and The difference is that the process of step S11 is omitted. In the following, the operation of the third embodiment will be described with respect to differences from the first embodiment.

In step S13, when X-rays are emitted from the radiation source 102, in step S13-2, based on the voltage values output from the current detection means 42A and the current detection means 42B by the reading control unit 22 of the radiation image detector 107. Then, the block region irradiated with X-rays is detected and output to the control unit 111.
In step S14, the block area detected in step S13-2 is designated as a reading area by the first reading control signal. Also, reading intervals such as every other line are instructed. The radiation image detector 107 reads a block area designated as a reading area and acquires a pre-captured image. The reading interval is not limited to every other line, and for example, the reading interval may be controlled to increase from the chest wall side useful for calculation of imaging conditions toward the opposite side. For example, the reading interval is set to 2 ^{n in} order from the chest wall side. In this way, the data amount of the pre-photographed image can be further reduced.
Note that in step S24, not the entire area of the detection unit 107a, but only the area irradiated with X-rays in the area in the detection unit 107a may be set as the reading area, as in the pre-imaging. Alternatively, the subject area Ha detected from the pre-photographed image may be acquired from the console 200, and the area corresponding to the subject area Ha may be read.

  As described above, according to the radiographic image capturing system 1, the control unit 111 causes the radiographic image detector 107 to read a predetermined region instead of the entire two-dimensional region of the detection unit 107a during pre-imaging. .

  Accordingly, since the data amount of the pre-captured image acquired by the pre-photographing can be reduced, it is possible to shorten the data transfer time to the console 200 and the processing time for determining the photographing conditions for the main photographing. . As a result, the time from the start of pre-photographing to the end of main photographing can be shortened.

  For example, the control unit 111 controls the radiation field of the radiation source 102 to be narrower at the time of pre-imaging than at the time of main imaging, and causes the radiation image detector 107 to read an area corresponding to the irradiation field in the detection unit 107a. Thus, the data amount of the pre-photographed image can be reduced.

  Further, the control unit 111 detects a breast region based on an output from a pressure sensor provided on the compression plate 109 or the subject table 104, and an area corresponding to the detected breast region in the detection unit 107a at the time of pre-imaging. Is read from the radiation image detector 107, the data amount of the pre-captured image can be reduced.

  Further, the control unit 111 can reduce the data amount of the pre-captured image by causing the radiation image detector 107 to read the region irradiated with the X-rays in the detection unit 107a during the pre-photographing.

  In addition, the control unit 111 can reduce the data amount of the pre-captured image by causing the radiological image detector 107 to read the region determined in advance on the chest wall side in the block region A or B during the pre-photographing.

  In addition, the control unit 111 can further reduce the data amount of the pre-captured image by causing the radiation image detector 107 to read at a predetermined line interval during the pre-photographing.

  Further, the control unit 111 keeps the position of the radiation image detector 107 in close contact with the subject table 104 at the time of pre-photographing even at the time of pre-photographing. It becomes possible to reduce the amount of data of the pre-photographed image.

  In addition, the description in this Embodiment mentioned above is an example of the suitable radiographic imaging system which concerns on this invention, and is not limited to this.

  For example, in the above embodiment, the area read by the detection unit 107a is a partial area including the subject area of the detection unit 107a to reduce the data amount of the pre-captured image. For example, the data amount of the pre-captured image may be reduced by deleting data corresponding to the region of the block region A or B that is not on the chest wall side, for example.

  In the above description, an example in which a hard disk, a semiconductor nonvolatile memory, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging system 100 Mammography apparatus 102 Radiation source 103 Main body part 104 Subject stand 105 Support shaft 106 Irradiation field adjuster 107 Radiation image detector 107a Detection part 108 Pressure sensor 109 Compression plate 110 Case 111 Control part 112 Operation Unit 113 display unit 114 communication unit 115 drive unit 116 position detection unit 117 power supply unit 118 bus 22 reading control unit 29 wireless communication unit 200 console 211 control unit 212 operation unit 213 display unit 214 storage unit 215 wireless communication unit 216 communication unit 217 bus

Claims (7)

A radiation source for irradiating the subject with radiation;
A radiation detection element that outputs charges according to the amount of radiation that has passed through the subject has a detection unit that is arranged in a two-dimensional manner, and obtains a captured image of the subject by reading the charge generated by the detection unit A radiological image detector;
Control means for irradiating a predetermined amount of radiation from the radiation source in advance before the main photographing of the subject and causing the radiation image detector to acquire a pre-photographed image for determining photographing conditions at the time of the main photographing. A radiographic imaging system,
The said control means is a radiographic imaging system which makes a predetermined area | region read from the said radiographic image detector instead of the two-dimensional whole area | region at the time of pre imaging | photography.   The control means controls the radiation field of the radiation source to be narrower at the time of pre-imaging than at the time of actual imaging, and causes the region corresponding to the radiation field of the radiation source in the detection unit to be read from the radiation image detector. The radiographic imaging system according to claim 1.   When the subject is a breast, the control means determines a breast region based on an output from a pressure sensor provided on a compression plate for compressing the breast or a subject table for placing the breast. The radiographic image capturing system according to claim 1, wherein a region corresponding to the detected breast region in the detection unit is read from the radiographic image detector during detection and pre-imaging.   The radiographic image capturing system according to claim 1, wherein the control unit causes the radiation image detector to read a region irradiated with radiation in the detection unit during pre-imaging. The radiographic imaging system performs mammography,
The detection unit of the radiological image detector includes a plurality of regions,
The radiographic image capturing system according to claim 1, wherein the control unit causes a region on the chest wall side of the detection unit to be read from the radiographic image detector during pre-imaging.   The radiographic imaging system according to any one of claims 1 to 5, wherein the control unit causes the radiographic image detector to read at a predetermined line interval during pre-imaging. The radiographic image capturing system is a system that performs magnified photographing of the subject,
The radiographic image capturing system according to any one of claims 1 to 6, wherein the control unit performs control to bring the position of the radiographic image detector into close contact with the subject during pre-imaging.

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