JPH0833621A - Breast photographing device - Google Patents

Abstract

PURPOSE:To provide a breast photographing device capable of automatically setting the detecting position of X-rays for automatic exposure control at the optimum position. CONSTITUTION:This device is equipped with a breast photographing unit 1 which photographs the breasts placed on a photographing board with the X-rays, an automatic exposure control unit 2 which detects the X-rays transmitting a part of the breasts and stops photographing when a timewise accumulated X-ray quantity arrives at a prescribed value, and a position decision unit 3 which makes slit light emitted from a slit light source advancing the breasts at least in two directions receive with two line sensors via the photographing board, and recognizes the shape of the breasts approximately based on four breast contour points obtained from the signal intensity change of each line sensor, and decides a position where the X-rays are detected by the automatic exposure control unit 2 based on the recognized shape of the breasts, and controls the automatic exposure control unit 2 so as to detect the X-rays at this position by the automatic exposure control unit 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mammography apparatus for photographing a breast at a predetermined density while controlling the photographing time by automatic exposure control.

[0002]

2. Description of the Related Art Mammography is mainly used to extract minute lesions of early breast cancer that cannot be detected by palpation or visual inspection. In this mammography, it is indispensable to perform compression imaging in which the breast is compressed to obtain a uniform thickness in order to increase the contrast of the region of interest that exists mainly in the center of the breast. In mammography, automatic exposure control (AEC; Automa) is used in order to avoid radiographic failure due to lack of density or excess and to minimize the exposure dose.
tic Exposure Control) is also mandatory.

By the way, in order to increase the contrast of the region of interest, it goes without saying that the X which has passed through this region of interest.
It is best to detect lines and use them for automatic exposure control.
Since the size of the breast varies from person to person, it is possible to
A plurality of AEC sensors can be installed and selectively used so that the detection position of the line can be changed, or one AEC sensor can be movably provided.

However, the operator must look at the compressed breast on the imaging table and select or move the AEC sensor each time the patient changes, which is very troublesome, and the position of the AEC sensor is experienced by the operator. I have decided to
It is not always possible to set the AEC sensor at the optimum position.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned circumstances, and an object thereof is to make it possible to automatically set an X-ray detection position for automatic exposure control to an optimum position. It is to provide a photographing device.

[0006]

According to a first aspect of the present invention, there is provided a mammography unit for taking an X-ray image of a breast placed on an imaging table, and an X-ray passing through a part of the breast is detected for a time period. An automatic exposure control unit for stopping imaging by the mammography unit when the X-ray dose cumulatively accumulated reaches a predetermined value,
At least two slit lights emitted from the slit light source toward the breast in at least two directions are passed through the imaging table.
At least 4 obtained from the signal intensity change of each of the at least two line sensors
Approximately recognize the breast shape based on the three breast contour points,
A position at which the automatic exposure control unit detects X-rays is determined based on the recognized breast shape, and a position is determined at which the automatic exposure control unit controls the automatic exposure control unit so as to detect X-rays. And means.

According to a fourth aspect of the present invention, a mammography unit that converts an X-ray image that has been emitted from an X-ray tube and passed through the breast into image data, and an X-ray that has passed through a part of the breast are detected to temporally detect the X-ray. And an automatic exposure control unit that stops imaging by the mammography unit when the accumulated X-ray dose reaches a predetermined value, and a breast shape is recognized from the image data, and the automatic exposure control is performed based on the recognized breast shape. Unit is X
Position determining means for determining a position for detecting a line and controlling the automatic exposure control unit so that the automatic exposure control unit detects an X-ray at this position.

[0008]

According to the first aspect of the present invention, most of the light passing through the imaging table can be captured by the line sensor, but most of the light emitted to the breast cannot be captured by the line sensor due to absorption or scattering. Therefore, the shape of the breast can be recognized as the contour point of the breast at the point where the signal intensity from the line sensor changes clearly. Moreover, since the breast shape is recognized from at least four contour points, a relatively accurate breast shape can be obtained by isosceles triangle or semi-ellipse approximation. Since the region of interest is concentrated in the approximate center of the breast, the optimum position for X-ray detection for automatic exposure control can be calculated as, for example, the barycentric position of an isosceles triangle or a semi-ellipse. Since the automatic exposure control unit detects the X-ray at this position, the above object can be achieved.

According to the invention of claim 4, the breast shape is recognized from the image data, the position where the automatic exposure control unit detects the X-ray is determined based on the recognized breast shape, and the automatic exposure control unit is Since the X-ray is detected at this position, the above object can be achieved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mammography apparatus according to the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows the arrangement of a mammography apparatus according to the first embodiment. FIG. 2 mainly shows the structural arrangement relationship between the slit light source and the line sensor in FIG. The mammography apparatus detects a mammography unit 1 that takes an X-ray image of a breast placed on an imaging table and an X-ray that has passed through a part of the breast, and the temporally accumulated X-ray dose reaches a predetermined value. Automatic exposure control unit 2 that stops the mammography unit 1 when it reaches
And a position determination unit 3 that determines a position for detecting X-rays for automatic exposure control.

When a tube voltage is applied from the high voltage generator 12 in response to a trigger from the X-ray controller 13, the X-ray tube 1
The X-rays from 1 are radiated in the shape of a cone beam toward the breast. The X-rays passing through the breast expose the X-ray film of the cassette 14 to light. An X-ray image as a grayscale image is printed on the X-ray film.

As shown in FIG. 2A, the X-ray tube 11 is housed at the tip of a pedestal 40, and the cassette 14 is the X-ray tube 11.
It is loaded in the imaging stand 41 in a state of facing the. The imaging is performed in a state where the breast placed on the top plate of the imaging table 41 is compressed by the compression plate 42. The compression plate 42 is supported by a lifting mechanism (not shown) so as to be able to move up and down.

FIG. 2B is a view of the inside of the imaging stand 41 viewed from the X-ray tube side with the top plate and the image pickup device removed. First, second and third AE of the automatic exposure control unit 2
The C sensors 21, 22, and 23 generally have a semicircular detection surface, and a photoelectric multiplier such as a photomultiplier, an ion chamber, or a semiconductor is mounted behind the scintillator plate. The first, second and third AEC sensors 21,
22 and 23 are discretely arranged in order in the photographing table 41 at different positions along the top plate, specifically, from the edge of the photographing table 41 in contact with the chest. 1st, 2nd, 3rd A
The detection signals of the EC sensors 21, 22, 23 are the selector 2
Alternatively, it is sent to the integrator 25 via 4. Integrator 25
Periodically repeats (temporarily) integrates (accumulates) the input detection signal, and outputs a cumulative signal corresponding to the cumulative X-ray dose to the comparator 27 each time it is accumulated. In the comparator 27,
A reference signal corresponding to the reference density is supplied from the reference density setter 26. The comparator 27 compares the accumulated signal with the reference signal, and when the accumulated signal reaches the reference signal, in other words, when the accumulated X-ray dose reaches a predetermined value, for example, the imaging end signal is X when the polarity of the voltage is reversed. It is output to the line controller 13. At this time, the X-ray controller 13 instructs the high voltage generator 12 to stop the X-ray exposure from the X-ray tube 11 and terminate the imaging.

The slit light source 30 of the position determining unit 3
Is attached to, for example, the tip of a compression plate 42 retracted from the X-ray flux from the X-ray tube 11 to the cassette 14, and emits slit light having a width that traverses at least the breast. The slit light from the slit light source 30 is split into at least two directions via, for example, a spectroscope, and is reflected at different reflection positions of the imaging stand 14 as shown in FIGS. 40 of at least two line sensors 31,
The light is received by each of 32. The two line sensors 31 and 32 are independently held by the gantry 40 so as to be vertically movable so that the reflected light can be received regardless of whether the slit light source 30 is vertically moved as the compression plate 42 is moved up and down. The light reflected by the shooting table 14 can be captured by the line sensors 31 and 32.
Most of the light applied to the breast cannot be captured by the line sensors 31 and 32 due to absorption and scattering. The output of each of the line sensors 31 and 32 is a breast shape recognition circuit (SRC) 3
Sent to 3. The breast shape recognition circuit 33 recognizes the breast shape with the points at which the signal distributions of the line sensors 31 and 32 change clearly as the breast contour points. Since at least four contour points can be obtained by the two line sensors 31 and 32, the breast shape recognition circuit 33 approximately recognizes the breast shape as an isosceles triangle or a semi-ellipse from the positional relationship between these four contour points. To do. The position determining circuit 34 calculates the barycentric position of, for example, an isosceles triangle or a semi-ellipse based on the breast shape recognized by the breast shape recognizing circuit 33, and the AEC sensor 21, 22, 23 which matches or is closest to the barycentric position.
Is selected and a select signal is supplied to the selector 24. Since the region of interest for medical examinations such as breast cancer is concentrated in the approximate center of the breast, it is possible to calculate the optimum position of X-ray detection for automatic exposure control as, for example, the position of the center of gravity of an isosceles triangle or a semi-ellipse. it can.

According to the select signal, the AEC sensor 21,
Either one of 22 and 23 is selectively connected to the integrator 25, and the output signal of any of the AEC sensors 21, 22 and 23 is utilized for automatic exposure control. The signal output is periodically repeated from the selected AEC sensor 21, 22, 23, and the integrator 25 integrates the output voltage of any one of the AEC sensors 21, 22, 23 and supplies it to the comparator 27. A reference voltage corresponding to the reference density from the reference density setting device 26 is supplied to the comparator 27. The comparator 27 compares the two,
Specifically, the difference is calculated, and this difference voltage is calculated by the X-ray controller 1
3 as an exposure control signal. The polarity of the voltage value (difference voltage) of the exposure control signal is inverted when the integrated voltage of the output from the AEC sensor reaches the reference voltage.

The X-ray controller 13 causes the high voltage generator 12 to emit X when the voltage value of the exposure control signal indicates polarity inversion.
Instruct to stop the radiation. As a result, the high voltage generator 1
The supply of the tube voltage and the tube current from 2 to the X-ray tube 11 is stopped, the exposure of the X-rays from the X-ray tube 11 is stopped, and the imaging is ended.

Next, the operation of this embodiment will be described. Prior to the actual shooting, the shape of the breast is approximately recognized,
To select one of the AEC sensors 21, 22, 23, the breast is placed on the imaging table 41, and the compression plate 4
The position determination unit 3 is activated under the pressure of 2. The slit light from the slit light source 30 is split into at least two directions via a spectroscope and is irradiated to the imaging table 14 and the breast. The light reflected by the photographing table 14 is captured by the line sensors 31 and 32. On the other hand, most of the light emitted to the breast is absorbed by the line sensor 31,
32 can not be caught.

The outputs of the line sensors 31 and 32 are sent to the breast shape recognition circuit 33. Breast shape recognition circuit 33
Recognizes the shape of the breast as a contour point of the breast at a point where the signal intensity in each signal distribution of the line sensors 31 and 32 changes clearly, that is, a boundary point between the breast and the imaging table 41.
FIG. 3A shows the breast shape in the case of isosceles triangle approximation, and FIG. 3B shows the breast shape in the case of semi-ellipse approximation. Breast shape recognition circuit 3
3 defines the imaging table 41 as two-dimensional coordinates, and at these coordinates, contour points P12, P12 on the known first reflection position,
The contour points P21 and P22 on the first reflection position are distributed, and an isosceles triangle passing through these four points is obtained, or a semi-ellipse is obtained by curve fitting to approximate the breast shape.
Further, the breast shape recognition circuit 33 calculates the base a and the height b in the case of an isosceles triangle, and the long axis a and the short axis b in the case of a semi-ellipse as the feature quantity indicating the size of the breast shape. The feature amount indicating the size of the breast shape is calculated by the AEC sensor 2
An iris mechanism as shown in FIG. 5 (a) is arranged on the front surface of the AEC sensor as 1, 22 and 23, and
As shown in (b), a random accessible solid-state image pickup device having a horizontal horizontal scanning circuit is provided behind the scintillator layer for converting X-rays into light and an arbitrary region is provided through the amorphous silicon (a-si). It is used as a parameter to change the size of the lighting field when the one that can change the size of the lighting field is output so that only the element signal can be output. The size of the lighting field can be changed accordingly. The shaded portion in FIG. 5B shows the photosensitive element group read out by random access for automatic exposure control from the solid-state imaging device.

The position determining circuit 34 includes a breast shape recognition circuit 3
3 calculates the barycentric position of an isosceles triangle or a semi-ellipse that represents the breast shape that is approximately recognized, selects the AEC sensor 21, 22, 23 that matches or is closest to this barycentric position, and sends the select signal to the selector 24. Supply. As described above, since the region of interest for screening for breast cancer is concentrated in the approximate center of the breast, the center of gravity of an isosceles triangle or a semi-ellipse is the optimum position for X-ray detection for automatic exposure control. Become.

According to the select signal, the AEC sensor 21,
Either one of 22 and 23 is selectively connected to the integrator 25, and the output signal of any of the AEC sensors 21, 22 and 23 is utilized for automatic exposure control. Note that, as shown in FIG. 4, when one AEC sensor is supported so as to be vertically and horizontally movable along the surface of the imaging base 41, the position determination circuit 34 is provided.
This AEC sensor is moved to the position of the center of gravity calculated by.

After the X-ray is emitted from the X-ray tube 11 and the photographing is actually started, the selected AEC sensor 2
1, 22 or 23, the detection signal is periodically output from the integrator 2
5 and sequentially added, that is, integrated by the integrator 25, and the integrated voltage is compared by the comparator 27 with the reference voltage according to the reference density from the reference density setting unit 26. For example,
The comparator 27 subtracts the reference voltage from the integrated voltage, the difference voltage is supplied to the X-ray controller 13 as an exposure control signal, the integrated voltage reaches the reference voltage, and the voltage value (differential voltage) of the exposure control signal changes from positive to negative. When the polarity is inverted to negative, that is, when the cumulative X-ray dose reaches a predetermined value, the X-ray controller 13 instructs the high voltage generator 12 to generate a tube voltage from the high voltage generator 12 to the X-ray tube 11. , The tube current supply is stopped, the X-ray exposure from the X-ray tube 11 is stopped, and the imaging is ended.

As described above, in this embodiment, the position of the X-ray detection for automatic exposure control can be set without the intervention of the operator, so that the labor for adjusting the position of the AEC sensor by the operator is eliminated and the operation is stable. It is possible to determine the optimum position for. (Second Embodiment) FIG. 6 shows the arrangement of a mammography apparatus according to the second embodiment. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Here, instead of the X-ray film of the first embodiment, as the image pickup means, a scintillator layer that converts X-rays into light, amorphous silicon (a-si), and a horizontal water direct scanning circuit are provided, and random access is possible. The solid-state imaging device 51 and the solid-state imaging device 51 are sequentially stacked from the X-ray tube 11 side. The signal output read from the solid-state imaging device 51 by the read control of the scan controller 52 is
It is digitized through an analog-digital converter (not shown) and selectively sent through the selector 53 to the output unit 54 for displaying and recording image data and the position determining unit 3.

In this embodiment, in order to determine the position of X-ray detection for automatic exposure control, prior to actual photographing,
Pre-shooting is performed with X-rays of lower energy than actual shooting. During this pre-shooting, the selector 53 is controlled by the system controller 57, and the output of the solid-state imaging device 51 is connected to the position determination unit 3. Solid-state imaging device 5
The digital image data picked up by 1 is sent to a breast shape recognition circuit 56 via a frame memory 55, where the contour of the breast is recognized as a breast shape. As a method for this contour recognition, as shown in FIG. 7C, the image data is differentiated along a horizontal line, and its inflection point, that is, the point at which the signal strength characteristically changes is identified as a contour point. Repeat what you do, changing the horizon. X-rays that have passed through the breast and are attenuated have a clearly lower X-ray energy when they reach the scintillator layer, as compared to X-rays that do not pass through the breast, and therefore the contour points of the breast have a characteristic signal strength. It must be an inflection point that changes. In addition, since pre-imaging is performed with X-rays of lower energy than actual imaging, S / N is lower than in actual imaging, but X-rays that have been attenuated by passing through the breast do not pass through the breast. Since the X-ray energy when reaching the scintillator layer is obviously lower than that of the X-ray, there is no influence on the identification of the inflection point.

This recognized breast shape data is sent to the position determining circuit 34, where the position of the center of gravity of the breast shape is calculated as the position for X-ray detection for automatic exposure control.
The position determining circuit 34 is similar to the first embodiment described above in that the AEC sensors 21 and 2 that match or are closest to the center of gravity position.
Select either 2 or 23 to use for automatic exposure control. Further, when one AEC sensor is supported so as to be vertically and horizontally movable along the surface of the imaging base 41, the AEC sensor is moved to the center of gravity calculated by the position determining circuit 34. Further, the breast shape recognition circuit 56 calculates the long axis and the short axis of the breast as the feature amount indicating the size of the breast shape. The feature quantity indicating the size of the breast shape is the AEC sensors 21, 22, and 23, and the iris mechanism as shown in FIG. 5A is arranged on the front surface of the AEC sensor, or the feature quantity shown in FIG. A random access solid-state imaging device having a horizontal horizontal scanning circuit via amorphous silicon (a-si) is provided behind the scintillator layer for converting X-rays into light, and an element only in an arbitrary region is provided. When the one that can change the size of the lighting field so that a signal can be output is used, it is used as a parameter for changing the size of the lighting field, and the lighting is adjusted according to the size of the breast. The size of the field can be changed.

In the present embodiment, as in the first embodiment, the position of the X-ray detection for automatic exposure control can be set without the intervention of the operator, so that the trouble of adjusting the position of the AEC sensor by the operator is eliminated. In addition, the optimum position can be stably determined. Further, in the present embodiment, since the solid-state image pickup device for picking up a breast image can be used also for the recognition of the breast shape, the slit light source, the line sensor, etc. can be eliminated as in the first embodiment.

In the above description, the breast shape recognition circuit 56 recognizes the breast shape, and the position determination circuit 34 determines the X-ray detection position for automatic exposure control based on the breast shape. As shown in FIG. 7A, the image is divided into a plurality of regions, and the total value (or average value) of the pixel values of each region is compared between the regions to obtain the highest total value, that is, the highest density. By selecting a region and determining the center position of this region as the position for X-ray detection for automatic exposure control, or comparing pixel values between discrete points of an image as shown in FIG. 7B. , The highest pixel value, that is, the discrete point having the highest density may be selected, and the position of this point may be determined as the position of X-ray detection for automatic exposure control. (Third Embodiment) FIG. 8 shows the arrangement of a mammography apparatus according to the third embodiment. The same parts as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. The feature of this embodiment is that a scintillator layer for converting X-rays into light, amorphous silicon (a-si),
The point is that the output of the charge-accumulation type solid-state imaging device 51 having a horizontal water scanning circuit and capable of random access is used for automatic exposure control. The pre-imaging for recognizing the breast shape is the same as that of the second embodiment, and therefore the description thereof is omitted here. By this pre-imaging, the breast shape is recognized, the position and area of X-ray detection for automatic exposure control are determined,
It is supplied to the system controller 57.

When the actual photographing is performed and the X-rays are continuously exposed, the system controller 57 connects the selector 61 to the position determining unit 3 side. The scan controller 52 controlled by the system controller 57 outputs only one signal charge in the X-ray detection area for automatic exposure control determined by the position determination circuit 3 from the solid-state imaging device 51 during imaging. The frame data is repeatedly read at a constant frame rate. The position determination circuit 3 may set an X-ray detection area for automatic exposure control in a free shape, or may divide a frame of the solid-state imaging device 51 into a plurality of areas and select a specific area. .

The X read from the solid-state image pickup device 51.
The frame data relating to the line detection area includes selector 53,
It is sent to the interframe integration circuit 62 of the position determination unit 3 via 61. The inter-frame integration circuit 62 integrates between all the frames captured from the start of capturing to the present. The frame data integrated by the inter-frame integration circuit 62 is sent to and held in the frame memory 63, read out as a pixel data string from the frame memory 63, and all the pixels are integrated by the in-frame integrator 64. This integrated value is compared with the reference value from the reference density setting unit 26 by the comparator 27 and used for automatic exposure control.

The comparison result of the comparator 27 is supplied to the X-ray controller 13 as an exposure control signal, and when the cumulative X-ray dose reaches a predetermined value, the X-ray controller 13 instructs the high voltage generator 12 to High voltage generator 12 to X-ray tube 1
1 to stop the supply of the tube voltage and the tube current to the X-ray tube 11
The exposure of X-ray from is stopped and the photographing is ended.

After the photographing is completed, the system controller 57 controls the selectors 53 and 61 to make the solid-state image pickup device 51.
Are connected to the synthesis circuit 65. Then, the system controller 57 controls the scan controller 52 to cause the synthesizing circuit 65 to read the image data from the solid-state imaging device 51. This image lacks data in the X-ray detection area for automatic exposure control. Therefore, the system controller 57 controls the frame memory 63 to control the X for automatic exposure control held in the frame memory 63.
The data in the line detection area is read by the synthesis circuit 65,
It is combined into one frame and completed as breast image data.

As described above, according to the present embodiment, in addition to the effects of the first and second embodiments described above, the solid-state image pickup device 51 is used not only for capturing a normal breast image, but also for recognizing a breast shape and automatically exposing the breast shape. Can also be used for
The EC sensor is no longer required, and the cost can be reduced and the size can be reduced.

In the above description, the breast shape recognition circuit 56 recognizes the breast shape, and the position determination circuit 34 determines the X-ray detection position for automatic exposure control based on the breast shape. As shown in FIG. 7A, the image is divided into a plurality of regions, and the total value (or average value) of the pixel values of each region is compared between the regions to obtain the highest total value, that is, the highest density. By selecting a region and determining the center position of this region as the position for X-ray detection for automatic exposure control, or comparing pixel values between discrete points of an image as shown in FIG. 7B. , The highest pixel value, that is, the discrete point having the highest density may be selected, and the position of this point may be determined as the position of X-ray detection for automatic exposure control. The present invention is not limited to the above-mentioned embodiments, but can be implemented with various modifications.

[0033]

According to the first aspect of the present invention, most of the light passing through the imaging table can be captured by the line sensor, but most of the light radiated on the breast can be captured by the line sensor due to absorption or scattering. Therefore, the breast shape can be recognized as a contour point of the breast at a point where the signal intensity from the line sensor changes clearly, and the breast shape can be recognized from at least four contour points. Since a relatively accurate breast shape can be obtained by the semi-ellipse approximation, and the region of interest is concentrated in the approximate center of the breast, the optimal position for X-ray detection for automatic exposure control is the isosceles triangle or semi-ellipse. For example, the position of the center of gravity can be calculated, and the automatic exposure control unit detects the X-rays at this position. Therefore, the detection position of the X-rays for automatic exposure control can be automatically set to the optimum position. It is possible to provide a shadow device.

According to the invention of claim 4, the breast shape is recognized from the image data, the position where the automatic exposure control unit detects the X-ray is determined based on the recognized breast shape, and the automatic exposure control unit is Since the X-ray is detected at this position, it is possible to provide a mammography apparatus that can automatically set the X-ray detection position for automatic exposure control to the optimum position.

[Brief description of drawings]

FIG. 1 is a block diagram of a mammography apparatus according to a first embodiment.

FIG. 2 is a diagram showing a structural arrangement relationship between a slit light source and a line sensor in FIG.

FIG. 3 is a diagram illustrating a breast shape approximation method.

FIG. 4 is a view showing a modified example of the AEC sensor.

FIG. 5 is a diagram showing another modification of the AEC sensor.

FIG. 6 is a block diagram of a mammography apparatus according to a second embodiment.

FIG. 7 is a diagram illustrating a breast shape recognition method.

FIG. 8 is a block diagram of a mammography apparatus according to a third embodiment.

[Explanation of symbols]

1 ... Mammography unit, 2 ... Automatic exposure control unit, 3
... Position determination unit, 11 ... X-ray tube, 12 ... High-voltage generator, 13 ... X-ray controller, 14 ... Cassette, 21 to 23 ... AEC sensor, 24 ... Selector, 25 ... Integrator, 26 ... Reference concentration setting device , 27 ... Comparator, 30 ... Slit light source, 31, 32 ... Line sensor, 33 ... Breast shape recognition circuit, 34 ... Positioning circuit.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Masayuki Nishiki 1385-1 Shimoishigami, Otawara-shi, Tochigi Stock company Toshiba Nasu factory (72) Inventor Koichiro Nabuchi 1385-1385 Shimoishi, Otawara, Tochigi Stock company Toshiba Nasu factory (72) Inventor Toru Saisu 1385-1 Shimoishigami, Otawara, Tochigi Prefecture Stock company Toshiba Nasu factory (72) Inventor Takayuki Tomisaki 1385-1 Shimoishigami, Otawara city, Tochigi prefecture Company Toshiba Nasu Factory (72) Inventor Shinichi Yamada 1385-1 Shimoishigami, Otawara-shi, Tochigi Stock Company Toshiba Nasu Factory (72) Inventor Katsuyuki Taguchi 1385-1 Shimoishigami, Otawara-shi, Tochigi Toshiba Nasu Factory

Claims (8)

[Claims] 1. A mammography unit for radiographing a breast placed on an imaging table with an X-ray, and an X-ray that has passed through a part of the breast is detected, and the cumulative X-ray dose reaches a predetermined value. And an automatic exposure control unit for stopping the imaging by the mammography unit, and slit light emitted from the slit light source toward the breast in at least two directions is received by at least two line sensors via the imaging table. Then, the breast shape is approximately recognized based on at least four breast contour points obtained from the change in the signal intensity of each of the at least two line sensors, and the automatic exposure control unit performs X-ray recognition based on the recognized breast shape. Position determining means for determining a position for detecting a line and controlling the automatic exposure control unit so that the automatic exposure control unit detects an X-ray at this position. Mammography apparatus according to claim and. 2. The position determining means determines, based on the recognized breast shape, a shape of a daylighting field in which the automatic exposure control unit detects an X-ray passing through a part of the breast, and the automatic exposure control unit. 2. The mammography apparatus according to claim 1, further comprising a randomly accessible solid-state imaging device, wherein a detection signal of the solid-state imaging device in the lighting field determined by the position determining means is utilized for automatic exposure control. . 3. The mammography unit has an X-ray tube, a conversion means for converting the X-rays passing through the breast into light, and a randomly accessible solid-state imaging device for imaging the output light of the conversion means. The mammography apparatus according to claim 1, wherein the automatic exposure control unit captures a signal output of the solid-state imaging device in the light-collecting field determined by the position determining means and utilizes it for automatic exposure control. 4. A mammography unit that captures as an image data an X-ray image that has been emitted from an X-ray tube and that has passed through a breast, and X-rays that have passed through a portion of the breast are detected and accumulated in time. An automatic exposure control unit that stops imaging by the mammography unit when the dose reaches a predetermined value, and recognizes a breast shape from the image data, and based on the recognized breast shape, the automatic exposure control unit uses X-rays. And a position determining means for controlling the automatic exposure control unit so that the automatic exposure control unit detects the X-ray at this position. 5. The automatic exposure control unit has a plurality of X-ray sensors arranged at different positions along a top plate of the imaging table, and the plurality of X-rays are arranged according to the positions determined by the position determining means. The mammography apparatus according to claim 1 or 4, wherein a sensor is selectively used. 6. The automatic exposure control unit has an X-ray sensor movable along the imaging table, and sets the X-ray sensor at the position determined by the position determining means. The mammography apparatus according to claim 1 or claim 4. 7. The position determining means determines, based on the recognized breast shape, a shape of a lighting field in which the automatic exposure control unit detects an X-ray passing through a part of the breast, and the automatic exposure control unit. The mammography apparatus according to claim 4, wherein a signal output of the solid-state imaging device in the lighting field determined by the position determining means is captured and utilized for automatic exposure control. 8. The mammography apparatus according to claim 4, wherein the automatic exposure control unit captures a part of the image data and utilizes it for automatic exposure control.