JP2007229363A - Radiographic image photographing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently use the output bit number of an AD converter for converting a signal voltage from a solid-state detector to a digital value. <P>SOLUTION: In this radiographic image photographing apparatus, when a breast 44 which is a body to be photographed is set to the photographing base 36 of the radiographic image photographing apparatus, the thickness t of the breast 44 is detected with a thickness detector 39, the signal maximum value of a photographed radiographic image is predicted in a signal maximum value prediction part 123 on the basis of the detected thickness t of the body to be photographed and the name of the breast 44, and the gain of an integrating amplifier 102 is adjusted so that the predicted signal maximum value corresponds to the maximum value of the output bit number (resolution) of the AD converter in an adjustment part 124. Thus, setting is easily performed in a short period of time so as to efficiently use all the resolution of the AD converter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radiographic image capturing apparatus that captures a radiographic image of a subject using a solid detector such as an FPD (Flat Panel Detector).

  For example, in a radiographic imaging apparatus for medical diagnosis or the like such as an X-ray mammography apparatus (mammography apparatus), a charge obtained by detecting radiation transmitted through a subject is temporarily stored in a power storage unit of a solid state detection element. Various solid-state detectors that accumulate, convert the accumulated charges into image signals representing radiation image information, and output the signals are proposed and put into practical use (Patent Document 1).

  In such a solid-state detector, from the viewpoint of facilitating signal processing, an analog image signal obtained by amplifying the output of the solid-state detector with an integrating amplifier is converted into a digital value by an AD converter, and image processing is performed. An image of the imaging region is displayed on the display for interpretation and diagnosis.

  In general, the AD converter is configured to convert a set full-scale voltage (reference voltage) into a digital value using all the output bit numbers (resolution).

  Various techniques for using all the output bit numbers of the AD converter have been proposed (Patent Documents 2 and 3).

  In Patent Document 2, the minimum voltage value and the maximum voltage value of the input analog signal are detected in advance, and the AD converter is set by setting the full-scale voltage (reference voltage) of the AD converter to the minimum voltage value and the maximum voltage value. There has been proposed an image data conversion apparatus that uses all the output bits of a device without waste.

  In Patent Document 3, a correspondence table of radiation exposure conditions such as tube voltage, tube current, and exposure time and gain control of the integration amplifier is provided, and the integration is performed with reference to the correspondence table according to the radiation exposure conditions. An X-ray diagnostic apparatus has been proposed in which the gain of an amplifier is determined so that the output amplitude of the integrating amplifier becomes the full-scale voltage of the AD converter.

JP 2004-154409 A JP 2000-59221 A Japanese Patent Laid-Open No. 11-94532

  However, in the technique for determining the gain of the integration amplifier according to the radiation exposure conditions proposed in Patent Document 3, the gain of the integration amplifier is determined at the maximum level at the imaging location where the subject is not present. Therefore, there is a drawback in that all the output bits of the AD converter cannot be used without waste.

  In the technique proposed in Patent Document 2, all the output bits of the AD converter can be used without waste, but the full-scale voltage is detected after detecting the minimum voltage value and the maximum voltage value of the input signal in advance. Therefore, it takes time to determine the full-scale voltage, that is, it takes time to acquire the radiographic image.

  The present invention has been made in consideration of such problems, and an AD converter that converts a radiographic signal into a digital value when a radiographic image of a subject is captured by a solid state detector. It is an object of the present invention to provide a radiographic imaging apparatus that can set the number of output bits so that all the output bits can be used easily and without waste in a short time.

  A radiographic image capturing apparatus according to the present invention is a radiographic image capturing apparatus that captures a radiographic image of an object to be imaged with a solid-state detector and converts the radiographic image signal into a digital value with an AD converter. 1) to (4).

  (1) A thickness detector that detects the thickness of the object to be imaged when the object to be imaged is set with respect to the imaging table of the radiographic imaging device, and the detected object thickness and the object to be imaged Based on the body, a signal maximum value prediction unit that predicts the signal maximum value of the radiographic image taken, and the predicted signal maximum value corresponds to the maximum value represented by the number of output bits of the AD converter, And an adjustment unit for adjusting a full-scale voltage of the AD converter or adjusting a gain of an amplifier arranged between the input side of the AD converter and the solid state detector.

  According to the invention having the feature (1), when the object to be imaged is set on the imaging table of the radiographic imaging apparatus, the thickness of the object to be detected is detected by the thickness detector, and the detected object to be detected is detected. Based on the imaging body thickness and the object to be imaged, the signal maximum value prediction unit predicts the signal maximum value of the captured radiographic image, and the adjustment unit displays the predicted signal maximum value as the number of output bits of the AD converter. Since the full-scale voltage of the AD converter is adjusted so as to correspond to the maximum value to be set, or the gain of the amplifier arranged between the input side of the AD converter and the solid-state detector is adjusted. Thus, it is possible to set so that all the output bits of the AD converter can be used without waste in a short time.

  (2) In the invention having the above feature (1), the signal maximum value predicting unit predicts the prediction of the signal maximum value of the radiographic image taken in consideration of radiographic conditions. To do. According to the invention having the feature (2), in the invention having the feature (1), the prediction accuracy of the signal maximum value of the captured radiographic image can be further increased.

  (3) A thickness detector that detects the thickness of the object to be imaged when the object to be imaged is set with respect to the imaging table of the radiographic imaging device, and the detected object thickness and the object to be imaged A signal distribution prediction unit that predicts the signal distribution of the radiographic image taken based on the body, and the maximum value of the region of interest in the predicted signal distribution corresponds to the maximum value represented by the number of output bits of the AD converter And an adjustment unit for adjusting a full-scale voltage of the AD converter or adjusting a gain of an amplifier disposed between the input side of the AD converter and the solid-state detector, To do.

  According to the invention having the feature (3), when the object to be imaged is set on the imaging table of the radiographic image capturing apparatus, the thickness of the object to be imaged is detected by the thickness detector, and the detected object to be detected is detected. The signal distribution prediction unit predicts the signal distribution of the captured radiographic image based on the imaging body thickness and the object to be imaged, and the adjustment unit predicts the maximum value of the region of interest in the predicted signal distribution. The full-scale voltage of the AD converter is adjusted so as to correspond to the maximum value represented by the number of output bits, or the gain of the amplifier arranged between the input side of the AD converter and the solid-state detector is adjusted. As a result, it is possible to set the number of output bits of the AD converter so that all the output bits of the AD converter can be used without waste in a short time.

  (4) In the invention having the above feature (3), the signal distribution predicting unit predicts the prediction of the signal distribution of the radiographic image taken in consideration of radiographic conditions. According to the invention having the feature (4), in the invention having the feature (3), the prediction accuracy of the maximum signal level of the radiographic image taken can be further increased.

  In the radiographic image capturing apparatus according to the present invention, when capturing a radiographic image of an object to be captured by a solid state detector, the number of output bits of an AD converter that converts a captured radiographic image signal into a digital value can be reduced in a short time. It can be set so that it can be used easily without waste.

  FIG. 1 is an overall configuration diagram of a radiographic image processing system 10 including a mammography apparatus 12 that is a radiographic image capturing apparatus according to this embodiment.

  The radiographic image processing system 10 is a radiographic image information acquired by the mammography apparatus 12 as well as a mammography apparatus 12 that is a radiographic image acquisition apparatus that acquires radiographic image information of a mammo (breast) as a subject to be diagnosed. In contrast, a CAD (Computer Aided Diagnosis) device 14 that is an image processing device having an image processing unit that performs image processing such as automatic detection of a lesion site, and the CAD device 14 performs image processing for diagnosis by a doctor. Image display devices (viewers) 16 and 18 for displaying radiographic image information, an image output device (printer) 20 for outputting radiographic image information to a film, etc., and a server for accumulating radiographic image information to which a diagnosis result by a doctor is added The radiation image information storage device 22 is provided. These devices are connected to each other by a network 24.

  FIG. 2 is a configuration diagram of the mammography apparatus 12. The mammography apparatus 12 includes a base 26 that also serves as a support, 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 radiation source that irradiates the patient 32 with radiation. Of the arm member 30 and a radiation source storage unit 34 fixed to one end of the arm member 30 and a solid state detector 46 for detecting radiation transmitted through the diagnosis subject 32 and acquiring radiation image information. An imaging table 36 fixed to the other end, a pressing plate 38 that presses and holds the mammo of the person to be diagnosed 32 against the imaging table 36, an imaging table 36 and a pressing plate 38 arranged in the arm member 30. And a thickness detector 39 that measures the distance between the two as a subject thickness t. As the thickness detector 39, for example, a length measuring device using a magnetic scale or a potentiometer can be used.

  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 mammo of the person 32 to be diagnosed by rotating in the direction of arrow A about the rotation axis 28. The pressing plate 38 is provided between the radiation source storage unit 34 and the imaging table 36 in a state of being connected to the arm member 30 and is configured to be displaceable in the arrow B direction.

  On the other hand, the base 26 displays imaging information such as the imaging region and imaging direction of the diagnosis subject 32 detected by the mammography device 12, ID information of the diagnosis subject 32, and the like, and if necessary, these information. Is provided.

  FIG. 3 is an internal configuration diagram of the imaging stand 36 in the mammography apparatus 12 and shows a state in which a mammo 44 (subject to be imaged) that is an imaging region of the diagnosis subject 32 is set between the imaging stand 36 and the pressing plate 38.

  In the imaging table 36, radiation image information based on the radiation X output from the radiation source built in the radiation source storage unit 34 is accumulated, and is output to the solid detector 46 that outputs as electrical signals. In order to read the radiation image information stored and recorded, the reading light source 48 for irradiating the solid detector 46 with reading light, and the solid detector 46 erased to remove unnecessary charges accumulated in the solid detector 46. An erasing light source 50 for irradiating light and an exposure device 47 (exposure sensor) configured by a photodiode or the like for detecting the exposure amount of the radiation X are provided.

  The solid state detector 46 is a direct conversion type and light readout type radiation solid state detector that accumulates radiation image information including the radiation X transmitted through the mammo 44 as an electrostatic latent image and reads light from the reading light source 48. By scanning with this, an electric charge (current) corresponding to the electrostatic latent image is generated.

  More specifically, the solid state detector 46 is formed on a glass substrate, and includes a first conductive layer that transmits radiation X, a recording photoconductive layer that generates charges when irradiated with radiation X, A charge transport layer acting as a substantially conductive material for a transport polarity charge opposite to the latent image polarity charge, while acting as a substantially insulating material for the latent image polar charge charged in one conductive layer; The photoconductive layer for reading which produces | generates an electric charge by being irradiated and exhibits electroconductivity, and the 2nd conductive layer which permeate | transmits the radiation X are laminated | stacked in order. A power storage unit is formed at the interface between the recording photoconductive layer and the charge transport layer.

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

  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 reading light, which is a reading signal output from the line light source, onto the solid state detector 46. And having a line light source in which LED chips are arranged in a direction (main scanning direction) orthogonal to the extending direction of the linear electrode that is the second conductive layer of the solid state detector 46. By moving (step feed) in the scanning direction a), the entire surface of the solid state detector 46 is exposed and scanned.

  The erasing light source 50 is preferably a light source that emits and extinguishes light in a short time and has very little afterglow. For example, the erasing light source 50 extends in the arrangement direction of the LED chips constituting the reading light source 48, and the arrangement direction. A plurality of external electrode type rare gas fluorescent lamps arranged in a direction perpendicular to the direction can be used.

  FIG. 4 is a block diagram of a control circuit constituting the mammography apparatus 12.

  The control circuit of the mammography apparatus 12 includes a control unit 100 composed of a microcomputer, a radiation source 35 driven by the control unit 100, and charges corresponding to the radiation X incident from the radiation source 35. A solid state detector 46 that accumulates as an image, a high voltage supply unit that supplies a high voltage to the solid state detector 46, and a charge accumulated in the linear electrode 43 of the solid state detector 46 by a read signal from the reading light source 48. The integration amplifier 102 that generates the analog value P of the signal voltage corresponding to the read (read) electric charge (current), and the analog value P that is the output of the integration amplifier 102 is AD converted to a digital value Q of the signal voltage. An AD converter (ADC) 106, an information storage unit 62 for storing the digital value Q in a memory, and an interface (I / F) 6 for the network 24 And the exposure amount of the radiation X supplied from the exposure device 47 and the prescribed exposure amount, and the automatic exposure control for notifying the control unit 100 that the radiation X exposure amount has reached the prescribed exposure amount. (AEC) 110 and a thickness detector 39 that detects the object thickness t and supplies it to the controller 100.

  The microcomputer of the control unit 100 is a computer, and includes a CPU (Central Processing Unit), a ROM (including EEPROM), a RAM, an input / output device, a timer as a timing unit, and the like. The CPU functions as various functional means (functional units) by executing a program stored in the memory.

  In this embodiment, the control unit 100 functions as the adjustment unit 124, the signal distribution prediction unit 122, the signal maximum value prediction unit 123, and the like.

  Further, in the signal distribution table 112 which is the memory of the control unit 100, as shown in FIG. 5A, the object thickness when the mammo 44 which is the object to be imaged is set between the imaging table 36 and the pressing plate 38. When the signal distribution 120 using t as a parameter is compared with the signal distribution 121 and the like, they are stored in advance in the form of grams.

  Each of the signal distributions 120 and 121 includes a mammo part signal region 144 related to the mammo 44 and a missing part signal region 145 corresponding to the missing part.

  FIG. 5B shows an example of the area distribution of the mammo 44 and the blank portion 45 on the solid state detector 46.

  As can be seen from FIG. 5A, on the signal distributions 120 and 121, the signal value in the unaccompanied portion signal region 145 is higher than that in the mammo portion signal region 144, and It can be seen that there is a region where the frequency is approximately zero.

  The solid line signal distribution 120 is a predicted signal distribution corresponding to the assumed maximum thickness (maximum object thickness) of the mammo 44, and the dotted line signal distribution 121 is assumed to be the assumed minimum thickness (minimum object thickness) of the mammo 44. The signal distribution corresponding to the object thickness t (mammo thickness) between the assumed maximum thickness and the assumed minimum thickness is obtained by interpolation from the signal distribution 120 and the signal distribution 121. be able to.

  In addition to the mammo 44, the signal distribution table 112 is acquired in advance in relation to an object thickness for each object to be imaged (an imaged part) of the person 32 to be diagnosed, and is stored in the memory of the control unit 100. It is possible to leave.

  The radiation image processing system 10 according to this embodiment is basically configured as described above. Next, the operation thereof will be described with reference to the flowchart of FIG.

  First, in the imaging preparation process of step S1, the ID information related to the diagnosis subject 32, the imaging method of the diagnosis target 32, the imaging conditions of the radiation X, and the like are set using a console, an ID card, etc. (not shown). In this case, the ID information includes information such as the name, age, and sex of the person 32 to be diagnosed, and can be obtained from a higher-level device connected to the network 24 or an ID card possessed by the person 32 to be diagnosed. Is possible. In addition, the imaging method includes information such as an imaging region and an imaging direction instructed by a doctor, and can be acquired from a higher-level device connected to the network 24 or input by a technician from a console. These pieces of information can be displayed and confirmed on the display operation unit 40 of the mammography apparatus 12. Furthermore, the radiation X imaging conditions include mAs value, tube voltage, target, filter, focus size, and the like.

  Next, the engineer sets the mammography apparatus 12 to a predetermined state according to the designated imaging method and imaging conditions. For example, as a method of photographing the mammo 44, head-to-tail direction (CC) imaging (see FIG. 3) in which radiation X is irradiated from above, and side direction (ML) in which radiation X is irradiated from the side There is imaging, inside / outside oblique (MLO) imaging in which radiation X is applied from an oblique direction, and the arm member 30 is pivoted about the pivot axis 28 in accordance with these imaging methods.

  Next, in step S <b> 2, the diagnosis subject 32 is set to the designated imaging state with respect to the mammography apparatus 12. For example, when performing head-to-tail direction (CC) imaging of the left mammo 44 of the diagnosis subject 32, as shown in FIG. 3, after placing the left mammo 44 on the imaging table 36, the pressing plate 38 is depressed, A mammo 44 is held between the imaging stand 36 and the pressing plate 38.

  In step S3, as shown in FIG. 3, when the mammo 44 of the person to be diagnosed 32 is set with respect to the imaging table 36, the control unit 100 is an object to be imaged and is flattened immediately before the imaging. The object thickness t of the mammo 44 is detected by the thickness detector 39.

  In step S4, shooting is started. In this case, after the imaging region of the person 32 to be diagnosed is determined, the radiation source 35 stored in the radiation source storage unit 34 is driven to start exposure to the radiation X, and radiographic image information is captured.

  The radiation X transmitted through the mammo 44 held between the pressing plate 38 and the imaging table 36 is irradiated to the solid state detector 46 accommodated in the imaging table 36. Prior to photographing, the solid state detector 46 is irradiated with erasing light from the erasing light source 50 to remove unnecessary charges.

  At this time, the radiation X is directly exposed to the exposing device 47 through a portion where the mammo 44 is not set, that is, the element removal portion 45 (see FIGS. 3 and 4).

  In a state where a high voltage is applied between the first conductive layer and the second conductive layer from the high voltage supply unit 52, when the radiation X carrying the radiation image information is irradiated to the solid detector 46, the recording of the solid detector 46 is performed. Positive and negative charge pairs are generated in the photoconductive layer, and the negative charges are accumulated in a power storage unit formed at the interface between the recording photoconductive layer and the charge transport layer. The amount of the accumulated negative charge, that is, the latent image polar charge, is approximately proportional to the dose of the radiation X transmitted through the mammo 44. The positive charges generated in the recording photoconductive layer are attracted to the first conductive layer, and are combined with the negative charges supplied from the high voltage supply unit 52 and disappear.

  In step S5, when it is detected in the automatic exposure control unit 110 that the exposure amount of the radiation X being exposed detected by the exposure device 47 has reached the prescribed exposure amount, the automatic exposure control unit 110 In step S6, the control unit 100 ends the exposure of the radiation source 35 to the mammo 44 (ends imaging).

  After the radiographic image information is captured, in step S7, the signal distribution prediction unit 122 calculates the signal distribution of the radiographic image captured from information on the body thickness t to be imaged and the region of the diagnosis subject 32, here the mammo 44. Predict. In order to predict the signal distribution, the signal distribution table 112 (see FIG. 5A) corresponding to the person to be diagnosed 32 is read, and the signal distributions 120 and 121 with respect to the object thickness t detected and measured, or the signal distribution obtained by interpolating these signal distributions. Predicted signal distribution.

  Next, in step S8, the adjustment unit 124 corresponds to the maximum value of the output bit number (resolution) of the AD converter 106 (255 if the output bit number is 8 bits) in the prediction signal distribution in the predicted signal distribution. Thus, the gain of the integrating amplifier 102 is adjusted.

  For example, as illustrated in FIG. 7, when the predicted signal distribution is the signal distribution 121, the adjustment unit 124 knows the signal maximum value Smax1 of the region of interest in the signal distribution 121. The gain of the integrating amplifier 102 is adjusted so that the value Smax1 corresponds to the maximum value represented by the number of output bits of the AD converter 106. This signal maximum value Smax1 is an output range of the AD converter 106 necessary for analysis when the object thickness t is thin. Further, when the predicted signal distribution is the signal distribution 120, the adjustment unit 124 knows the signal maximum value Smax2 of the region of interest in the signal distribution 120. Therefore, the signal maximum value Smax2 of the region of interest is converted into the AD converter 106. The gain of the integrating amplifier 102 is adjusted so as to be the maximum value represented by the number of output bits. This signal maximum value Smax2 is an output range of the AD converter 106 necessary for analysis when the object thickness t is thick.

  When the gain of the integrating amplifier 102 is fixed, the full-scale voltage (reference voltage) of the AD converter 106 may be adjusted by the adjustment unit 124 so as to be the signal maximum values Smax1 and Smax2. Of course, both the gain and the full scale voltage may be adjusted so that the maximum value represented by the number of output bits of the AD converter 106 becomes the signal maximum values Smax1 and Smax2.

  The signal distribution predicting unit 122 replaces the signal maximum value predicting unit 123 that predicts only the signal maximum values Smax1 and Smax2 of the captured radiographic image based on the site of the person to be diagnosed 32 and the detected body thickness t. be able to. In this case, the object thickness t and the signal maximum values Smax1, Smax2 are determined in advance to determine the maximum value (255 for 8 bits, 4096 for 12 bits, etc.) related to the number of output bits of the AD converter 106. Is stored in the signal maximum value table 113.

  In this way, the integration amplifier 102 or the AD converter 106 is fully loaded so that the signal maximum values Smax1, Smax2, etc. of the region of interest of the diagnosis subject 32 become the maximum values represented by the number of output bits of the AD converter 106. After the scale voltage is adjusted, a radiation image reading process is performed in step S8.

  That is, when the reading light source 48 moves in the arrow direction (sub-scanning direction) a along the linear electrode 43 of the solid state detector 46 and is irradiated with reading light, positive and negative charge pairs are generated in the reading photoconductive layer. Then, the positive charge moves in the charge transport layer so as to be attracted to the negative charge (latent image polar charge) accumulated in the power storage unit, and is combined with the negative charge of the power storage unit and disappears. On the other hand, the negative charge generated in the reading photoconductive layer is combined with the positive charge supplied from the high voltage supply unit 52 to the second conductive layer and disappears. In this way, the negative charges accumulated in the solid state detector 46 are extinguished by charge coupling, and a current is generated in the solid state detector 46 due to the movement of the charge during the charge coupling.

  An analog value P obtained by amplifying the signal charge (signal current) for each pixel generated at each linear electrode of the solid state detector 46 by the integrating amplifier 102 is converted into a digital value Q by the AD converter 106 and stored in the information storage unit 62. Is done.

  In this way, the digital value Q of the entire surface of the solid state detector 46 is stored in the information storage unit 62. At this time, the information storage unit 62 is supplied with the imaging part information of the diagnosis subject 32 determined by the imaging part determination unit (not shown) via the display operation unit 40 and is determined by the position determination unit (not shown). Position information is supplied. Accordingly, the information storage unit 62 stores the radiation image information in a state associated with the imaging part information and position information of the diagnosis subject 32.

  The solid state detector 46 from which the radiation image information 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.

  On the other hand, each apparatus connected to the network 24 acquires radiation image information, its imaging region information, and position information from the mammography apparatus 12 via the network 24 and performs predetermined processing.

  That is, the CAD device 14 automatically detects a lesion site or the like with respect to the radiation image information in accordance with the acquired imaging site information and position information, and performs processing such as marking indicating the lesion site on the radiation image information. In this case, the radiographic image information is attached with the imaging site information and the position information, so that automatic detection processing of a lesion site or the like can be performed easily and with high accuracy.

  In addition, the image display devices 16 and 18 acquire the imaging region information and position information automatically acquired by the mammography device 12 and information such as the lesion site detected by the CAD device 14 via the network 24, and the information. Accordingly, a highly accurate diagnosis can be performed.

  Furthermore, imaging part information, position information, and radiation image information are transmitted to the image output device 20 and the radiation image information storage device 22 via the network 24 as necessary, and output to a film or the like using the image output device 20. At the same time, it can be stored in the radiation image information storage device 22.

  The network 24 constituting the radiation image processing system 10 can be configured by a wired LAN, a wireless LAN, infrared communication, communication via a serial cable, a telephone line, or the like. The network 24 is preferably configured to exchange information in accordance with, for example, a protocol based on DICOM (Digital Imaging and Communication in Medicine).

  Further, in this embodiment, the imaging part information, the imaging direction information, and the radiation image information may be held in a memory card without passing through the network 24, and information may be exchanged via the memory card.

  As described above, according to the above-described embodiment, when the mammo 44 as the subject to be photographed is set for the photographing stand 36 of the mammography apparatus 12, the thickness detector 39 detects the subject thickness t, Based on the detected object thickness t and the object being the mammo 44, the signal maximum value prediction unit 123 predicts the signal maximum value of the captured radiographic image, and the adjustment unit 124 predicts the signal maximum value. The full-scale voltage of the AD converter 106 is adjusted so as to correspond to the maximum value represented by the number of output bits of the AD converter 106, or is arranged between the input side of the AD converter 106 and the solid state detector 46. Since the gain of the integrating amplifier 102 is adjusted, the number of output bits of the AD converter 106 can be set so that it can be used without waste in a short time.

  Further, when the mammo 44 that is the subject to be photographed is set on the photographing stand 36 of the mammography apparatus 12, the thickness detector 39 detects the subject thickness t, and the detected subject thickness t and the subject to be sensed are detected. Is the mammo 44, the signal distribution prediction unit 122 predicts the signal distribution 120, 121, etc. of the captured radiographic image, and the adjustment unit 124 predicts the maximum of the region of interest in the predicted signal distribution 120, 121. The full-scale voltage of the AD converter 106 is adjusted so that the value corresponds to the maximum values Smax1 and Smax2 expressed by the number of output bits of the AD converter, or between the input side of the AD converter 106 and the solid state detector 46 Since the gain of the integrating amplifier 102 arranged in is adjusted, the number of output bits of the AD converter 106 can be set to a region of interest easily and without waste in a short time. It is possible.

  In this case, the signal maximum value predicting unit 123 or the signal distribution predicting unit 122 is a signal maximum value table 113 or a signal distribution table in which mAs values, tube voltages, targets, filters, focus sizes, and the like, which are radiographic X imaging conditions, are considered. By using 112, each prediction accuracy of the prediction of the signal maximum value of the radiographic image taken or the prediction of the signal distribution can be further increased.

  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.

It is a whole lineblock diagram of a radiographic image processing system containing a radiographic imaging device concerning this embodiment. It is a block diagram of the mammography apparatus as a radiographic imaging apparatus concerning this embodiment. It is an internal block diagram of the imaging stand in a mammography apparatus. It is a block diagram of a control circuit. FIG. 5A is an explanatory diagram of a signal distribution prediction table, and FIG. 5B is an explanatory diagram of a radiation distribution irradiated to the solid state detector. It is a flowchart with which operation | movement description of the radiographic imaging apparatus which concerns on this embodiment is provided. It is explanatory drawing of matching with the maximum value represented by the number of output bits of an AD converter, and a signal maximum value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Radiation image processing system 12 ... Mammography apparatus 32 ... Diagnosis person 39 ... Thickness detector 44 ... Mammo (object to be imaged) 46 ... Solid state detector 47 ... Exposing device 100 ... Control part 102 ... Integration amplifier 106 ... AD converter DESCRIPTION OF SYMBOLS 112 ... Signal distribution table 113 ... Signal maximum value table 122 ... Signal distribution prediction part 124 ... Adjustment part

Claims (4)

In a radiographic image capturing apparatus that captures a radiographic image of an object to be photographed by a solid state detector and converts a signal of the captured radiographic image into a digital value by an AD converter,
A thickness detector that detects the thickness of the object to be imaged when the object to be imaged is set with respect to an imaging table of the radiographic image capturing apparatus;
Based on the detected object thickness and the object to be detected, a signal maximum value prediction unit that predicts a signal maximum value of the captured radiographic image;
The full-scale voltage of the AD converter is adjusted so that the predicted maximum signal value corresponds to the maximum value represented by the number of output bits of the AD converter, or the input side of the AD converter and the solid state detection An adjustment unit for adjusting the gain of an amplifier disposed between the units;
A radiographic imaging apparatus comprising: The radiographic imaging apparatus according to claim 1,
The radiological image capturing apparatus, wherein the signal maximum value predicting unit predicts the maximum signal value of the captured radiographic image in consideration of radiographic conditions. In a radiographic image capturing apparatus that captures a radiographic image of an object to be photographed by a solid state detector and converts a signal of the captured radiographic image into a digital value by an AD converter,
A thickness detector that detects the thickness of the object to be imaged when the object to be imaged is set with respect to an imaging table of the radiographic image capturing apparatus;
A signal distribution prediction unit that predicts a signal distribution of the captured radiographic image based on the detected object thickness and the object to be imaged;
In the predicted signal distribution, the full-scale voltage of the AD converter is adjusted or the AD converter is adjusted so that the maximum value of the region of interest corresponds to the maximum value represented by the number of output bits of the AD converter. An adjustment unit for adjusting the gain of an amplifier disposed between the input side and the solid-state detector;
A radiographic imaging apparatus comprising: In the radiographic imaging device of Claim 3,
The signal distribution prediction unit predicts the signal distribution of the captured radiographic image in consideration of radiographic imaging conditions.

Images