JP2016171917A - X-ray imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray imaging apparatus with a simple structure, capable of appropriately performing auto exposure control and appropriately performing X-ray imaging control.SOLUTION: An X-ray imaging apparatus, when a plurality of AEC lighting fields for auto exposure exist, detects the existence of an AEC lighting field having a sensitivity area whose all part is not included in an X-ray irradiation area V, on the basis of positional information on the X-ray irradiation area Vand the AEC lighting fields' sensitivity areas. When one or more AEC lighting fields not completely included in the X-ray irradiation area Vexist, these AEC lighting fields are set to be unused. For example, when only an AEC lighting field Vhas a sensitivity area whose part is not included in the X-ray irradiation area V, the AEC lighting field Vis set to be unused. Thereby, the X-ray imaging apparatus can appropriately perform auto exposure control and appropriately perform X-ray imaging control, with a simple structure.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an X-ray imaging apparatus that performs X-ray imaging, and particularly to an automatic exposure control technique that automatically and optimally controls the exposure of X-ray imaging.

  The X-ray imaging apparatus includes an X-ray generator, an X-ray tube, an X-ray tube holding unit that holds the X-ray tube suspended from the ceiling or holds it from the floor, and an X-ray irradiation area from the X-ray tube as a leaf. And an X-ray detector (X-ray film, CR (Computed Radiography) or FPD (Flat Panel Detector)) for detecting X-rays. In addition, the subject is held using an X-ray imaging table (table or stand), and the X-ray detector is housed in the X-ray imaging table to perform X-ray imaging. When the X-ray detector is an FPD, an X-ray image (X-ray image) acquired from the FPD is transmitted to a digital device connected to the FPD and displayed on a monitor of the digital device (for example, non-patent literature) 1).

  In a collimator that controls an X-ray irradiation area from an X-ray tube by using a leaf, a rectangular X-ray irradiation field formed by the collimator is, for example, a vertical dimension adjustment knob and a horizontal dimension adjustment knob provided on the panel surface of the collimator. Thus, the length of the two sides can be adjusted. However, performing this adjustment while monitoring the subject on the X-ray imaging table while irradiating the subject with X-rays before the X-ray imaging leads to an increase in exposure of the subject.

  In order to prevent such exposure, the collimator normally has a built-in illumination field lamp as a light source and has a function of irradiating light instead of X-rays. By confirming the irradiation field of light adjusted so as to coincide with the irradiation field of X-rays, the position and size of the irradiation field can be adjusted before imaging without irradiating X-rays. The light irradiation start or irradiation end is performed by a light irradiation button. For example, each time the light irradiation button is pressed, the irradiation start and the irradiation end are alternately repeated.

  An operator such as an engineer adjusts the adjustment knob of the collimator and confirms the X-ray irradiation area corresponding to the imaging region of the subject in the light irradiation field. After that, be careful not to move the body of the subject, go out of the examination room surrounded by a material that does not transmit X-rays (for example, lead), and in the operation room, X-ray radio button of the X-ray generator Press to shoot.

  Also, X-ray imaging apparatuses equipped with automatic exposure control (AEC: Auto Exposure Control) that automatically and optimally controls the exposure of X-ray imaging are widely used (see, for example, Patent Documents 1 to 3). In this automatic exposure control (AEC), a part of X-rays (transmission X-rays) transmitted through the subject is detected within a specific detection range (hereinafter referred to as “lighting field”), and the detected X-rays are detected. Is converted into an electric signal (X-ray output signal), and the X-ray is cut off when the integral value of the electric signal (X-ray output signal) reaches an appropriate value. By performing this AEC, the integrated amount (incidence dose) of transmitted X-rays irradiated to the X-ray detector is set to an appropriate value, and thereby a desired luminance signal (pixel value) can be obtained.

  Usually, in an X-ray imaging apparatus equipped with an AEC, an exposure control detection unit (AEC detection unit) is installed on the subject side in a bucky (imaging table) that holds an X-ray detector. There are a plurality of lighting fields of the installed AEC detection unit, and a lighting field suitable for the imaging region is selected for each imaging. For example, in FIG. 2 and FIG. 3 of JP-A-2008-117641, there are three lighting fields (right side of the lighting field, center of the lighting field, and left side of the lighting field). During X-ray imaging, X-rays are immediately blocked when the incident dose of X-rays incident on the selected AEC light field exceeds a predetermined value.

  In Patent Document 1: Japanese Patent No. 5344807, an X-ray output signal is controlled in proportion to an area (effective area) in which an X-ray irradiation region is set in a lighting field (AEC lighting field) of an AEC detection unit. ing. Even when the X-ray dose is reduced by the collimator, the X-ray output signal is controlled in proportion to the effective area in this manner, so that the incident dose to the X-ray detector can be kept constant.

  When an X-ray detector typified by FPD or the like also serves as an AEC detection unit, the detection pixel in the AEC detection unit is divided into the time of the dose detection operation compared to the image detection pixel. Only the accumulation operation time is shortened. As a result, the pixel value of the detection pixel in the AEC detection unit is smaller than that of the image detection pixel, resulting in image quality degradation. Therefore, Japanese Patent Laid-Open No. 2013-135390 proposes correcting the pixel value in the detection pixel so that it is the same as the pixel value in the image detection pixel.

Japanese Patent No. 5344807 JP 2008-117641 A JP 2013-135390 A

“General Shooting System”, [online], Shimadzu Corporation, Internet <URL: http://www.med.shimadzu.co.jp/product s / x-ray / 08 / 01.html>

However, even in the case of the conventional example having such a configuration, there is a problem in that exposure is increased without automatic exposure control (AEC) being appropriately performed.
That is, when the operator adjusts the X-ray irradiation field (X-ray irradiation region) while performing X-ray imaging while checking the irradiation field of light as in the prior art, the subject or the like becomes a shadow, as shown in 4, actually detection field V _C, V _L, V _R of the sensitive region (effective area) is no longer included in the X-ray irradiated area V _I (one sensitive region in FIG. 4 the detection field V _R part is no longer included in the X-ray irradiated area V _I) problem arises. As a result, there is a possibility that the sensitivity area (effective area) of the lighting field set in advance may be reduced.

  Along with this, the X-ray incident dose per unit time incident on the AEC lighting field decreases by the amount of the blocked area, so that a predetermined total X-ray incident dose determined in advance to block the X-ray output is obtained. The time until reaching (the arrival time) becomes longer. As a result, the total X-ray incident dose output to the subject increases, resulting in unnecessary exposure to the subject. Similarly, the X-ray total incident dose is increased by the extension of the arrival time for the detection pixel region in the X-ray detector, so that the density (pixel value) is different in each region. This results in a line-captured image that is difficult to diagnose. Even if a plurality of AEC lighting fields are planned to be used, the sensitivity region of at least one of the AEC lighting fields may be reduced for the reasons described above.

  Further, normally, X-ray imaging is not performed at a position that reduces the sensitivity area of the AEC lighting field, and the position of the X-ray irradiation area with respect to the X-ray detector is determined in a predetermined positional relationship in imaging positioning. Therefore, when imaging is performed even at a position where the sensitivity area of the AEC lighting field is reduced, the position of the X-ray irradiation area with respect to the X-ray detector is different from the normal position in imaging positioning, and there is a possibility of erroneous imaging positioning. There is also. In addition, the output / display position of the X-ray image may change accordingly.

  Patent Document 1: Japanese Patent No. 5344807 discloses that the X-ray output signal is controlled in proportion to the area where the X-ray irradiation area in the AEC lighting field is set as described above. , A multiplier for multiplying a proportional value (ratio Y is 1 / Y) is required. Further, when the set area becomes small, the value of the X-ray output signal after multiplication (1 / Y) becomes large, and there is a possibility that the comparison detector that receives this output signal saturates. As a result, effective X-ray detection output blocking is not performed, and there is a possibility that the exposure to the subject increases.

  In the correction based on the ratio of the effective area in Patent Document 1: Japanese Patent No. 5344807, there is also a problem that the X-ray irradiation region itself is not accurately obtained by the scattered rays of the subject and accurate correction is not performed. In any case, automatic exposure control (AEC) may not be performed properly as a result of the X-ray irradiation area itself not being accurately determined.

  The present invention has been made in view of such circumstances, and provides an X-ray imaging apparatus capable of appropriately performing automatic exposure control and appropriately performing X-ray imaging control with a simple structure. With the goal.

In order to achieve such an object, the present invention has the following configuration.
That is, the X-ray imaging apparatus according to the present invention (the former invention) is an X-ray imaging apparatus that performs X-ray imaging, and an X-ray irradiation unit that irradiates an X-ray toward a subject and automatic exposure. There are a plurality of daylight fields, and which field to use is selected, the daylight field setting means for setting the selected daylight field, the X-ray irradiation area irradiated by the X-ray irradiation means, and Based on the position information of the sensitivity area of the lighting field, the lighting field detecting means for detecting the presence or absence of the lighting field where all the sensitivity areas are not included in the X-ray irradiation area, and not included in the X-ray irradiation area When one or more lighting fields are present, an unused setting unit that sets the corresponding lighting field to unused is provided.

  [Operation / Effect] According to the X-ray imaging apparatus according to the present invention (the former invention), when there are a plurality of lighting fields for automatic exposure, the position information of the X-ray irradiation area and the sensitivity field of the lighting field is used. Based on this, the lighting field detecting means detects the presence or absence of a lighting field where all the sensitivity areas are not included in the X-ray irradiation area. In a lighting field that is not included in the X-ray irradiation area, the sensitivity area is reduced, and when there is one or more lighting fields that are not included in the X-ray irradiation area (that is, a lighting field in which the sensitivity area is decreased), The corresponding daylighting field is set to unused by the unused setting means. Then, (1) select and set a lighting field other than the lighting field set to unused from the lighting field selected by the lighting field setting means, or (2) the lighting field set to unused. The lighting field setting means selects and sets a lighting field other than. When automatic exposure control and X-ray imaging control are performed using the remaining daylight field without using the daylight field in which the sensitivity region is reduced in this way, the remaining daylight field is necessary to block the X-ray output. The X-ray output is cut off at a predetermined value determined as the total incident X-ray dose. Therefore, appropriate automatic exposure control, and hence appropriate X-ray imaging control can be performed, and the density (pixel value) of the X-ray imaging image (X-ray image) obtained by imaging is constant. In addition, it is not necessary to accurately obtain the X-ray irradiation region due to the scattered rays of the subject, correction as in Patent Document 1: Japanese Patent No. 5344807, and a multiplier is not necessary. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.

  An X-ray imaging apparatus (the latter invention) according to an invention different from the former invention is an X-ray imaging apparatus for performing X-ray imaging, and an X-ray irradiation means for irradiating an X-ray toward a subject. Based on the positional information of the X-ray irradiation area irradiated by the X-ray irradiation means and the sensitivity area of the lighting field for automatic exposure, the entire area of the sensitivity area is not included in the X-ray irradiation area. A lighting field detecting means for detecting the presence or absence of a field, and a warning means for issuing a warning when there is a lighting field that is not included in the X-ray irradiation region, are provided.

  [Operation / Effect] In the former invention, there are a plurality of lighting fields. However, the X-ray imaging apparatus according to the present invention (the latter invention) can be applied to the case where only one lighting field is provided. it can. Unlike the former invention, the latter invention is newly provided with warning means. Similar to the former invention, according to the latter invention, based on the positional information of the X-ray irradiation area and the sensitivity area of the lighting field, the presence or absence of the lighting field where all the areas of the sensitivity area are not included in the X-ray irradiation area is determined. The daylight detection means detects. As described in the operation and effect of the former invention, the sensitivity region is reduced in the lighting field not included in the X-ray irradiation region. In the latter invention, when there is a lighting field that is not included in the X-ray irradiation area (that is, a lighting field in which the sensitivity area is reduced), the warning means described above issues a warning. If the warning is given to the operator by the warning means before X-ray imaging, it can be seen that the X-ray irradiation area is deviated or missing from the sensitivity area of the lighting field before X-ray imaging. Therefore, the operator adjusts the position of the subject and the X-ray irradiation area again, so that an appropriate total X-ray incident dose is incident on the lighting field. X-ray imaging control can be performed, and the density (pixel value) of an X-ray imaging image (X-ray image) obtained by imaging is constant. At this time, since the operator can recognize in advance that the imaging positioning is different from the normal, it is possible to correct if there is a mistake in the imaging positioning, and an X-ray image (X-ray image) can be corrected. ) Output and display position does not change. Further, the X-ray output signal from the daylighting field is the same as before by adjusting again, and a multiplier as in Patent Document 1: Japanese Patent No. 5344807 becomes unnecessary. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.

  The former invention and the latter invention may be combined. In the former invention, when there is a lighting field that is not included in the X-ray irradiation region, a warning means for issuing a warning is provided as in the latter invention. As described above, when there are a plurality of daylighting fields and there are one or more daylighting fields not included in the X-ray irradiation region, even when the corresponding daylighting field is set to be unused, before X-ray imaging. A warning may be given to the operator by warning means. Then, the operator adjusts the position of the subject and the X-ray irradiation area again so that an appropriate X-ray total incident dose is incident on the lighting field set to unused, and is set to unused. Set the daylighting field to be usable.

  The warning means may give a warning by light or may give a warning by sound. Moreover, you may warn combining both light and a sound. For example, the warning may always be performed with light, and the warning may be performed with sound before X-ray imaging.

  The warning means may issue a warning at the timing when the X-ray imaging operation is performed. That is, when there is a lighting field that is not included in the X-ray irradiation area, the warning means does not issue a warning at that time, and only the detection flag is set by the lighting field detection means, for example, at the timing when the X-ray imaging operation is performed. A warning is given based on the detection flag. Also in this case, the warning means may give a warning with light or may give a warning with sound.

  In the former invention and the latter invention, the X-ray irradiating means for limiting the area irradiated by the X-ray irradiating means is provided, and the positional information of the X-ray irradiated area is obtained from the X-ray irradiating means, the X-ray restricting means, (Based on the position information of each of the X-ray detection means). In this way, it is calculated for which position of the X-ray detection means the X-ray irradiation area is set. Then, the X-ray irradiation area is subjected to detection of the presence or absence of a lighting field (not included in the X-ray irradiation area) by the lighting field detection means.

  In the former invention and the latter invention, there is provided a relative position information storage means for storing relative position information between the sensitivity region of the lighting field and the X-ray detection means (detecting X-rays transmitted through the subject), By referring to the relative position information based on the position information of the line detection means, the position information of the sensitivity region of the lighting field is calculated. In this way, the relative position information is referred to based on the position information of the X-ray detection means, the position information of the sensitivity area of the lighting field is calculated, and the X-ray irradiation area is detected by the lighting field detection means (X-ray irradiation). It is used to detect the presence or absence of a lighting field (not included in the area).

According to the X-ray imaging apparatus according to the present invention (the former invention), when there are a plurality of lighting fields for automatic exposure, the sensitivity region is based on the positional information of the X-ray irradiation region and the sensitivity region of the lighting field. The daylight field detecting means detects the presence or absence of the daylighting field in which all the areas are not included in the X-ray irradiation area. If there is one or more lighting fields that are not included in the X-ray irradiation area, the unused setting means sets the corresponding lighting fields to unused. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.
Further, according to the X-ray imaging apparatus (the latter invention) according to the invention different from the former invention, all the sensitivity areas are X based on the positional information of the X-ray irradiation area and the sensitivity area of the lighting field. The lighting field detection means detects the presence or absence of a lighting field not included in the line irradiation region. If the daylighting field that is not included in the X-ray irradiation area exists, the warning means issues a warning. If the warning is given to the operator by the warning means before X-ray imaging, it can be seen that the X-ray irradiation area is deviated or missing from the sensitivity area of the lighting field before X-ray imaging. Therefore, the operator can adjust the position of the subject and the X-ray irradiation area again. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.

It is the schematic of the X-ray imaging apparatus which concerns on each Example. It is a block diagram of the X-ray imaging apparatus which concerns on each Example. It is a schematic diagram of the position of AEC lighting field. It is a schematic diagram of an AEC lighting field and an X-ray irradiation area.

Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram of an X-ray imaging apparatus according to each embodiment, and FIG. 2 is a block diagram of the X-ray imaging apparatus according to each embodiment. In Example 1, including Example 2 described later, a flat panel X-ray detector (FPD) will be described as an example of X-ray detection means.

  As shown in FIG. 1 including Example 2 to be described later, an X-ray imaging apparatus 1 according to Example 1 includes an X-ray tube suspension unit 2 that suspends and supports an X-ray tube 22 so as to be movable along a ceiling. X-ray imaging stand unit 3 that performs X-ray imaging while subject M is in a standing posture, X-ray table unit 4 that performs X-ray imaging while subject M is in a supine posture, and X-rays of subject M An image processing unit 5 (not shown in FIG. 1) that performs image processing on an image is provided. As shown in FIG. 2, the X-ray tube suspension unit 2, the X-ray imaging stand unit 3, the lying table unit 4, and the image processing unit 5 are electrically connected to each other by a communication cable 6. The X-ray tube suspension unit 2, the X-ray imaging stand unit 3, the lying table unit 4 and the image processing unit 5 are configured to be able to communicate with each other.

  As shown in FIG. 1, the X-ray tube suspension unit 2 includes a column 21 that can move along the ceiling and can be vertically expanded and contracted, and an X-ray tube 22 that is supported by the column 21 and whose direction can be adjusted. Yes. Further, as shown in FIG. 2, the X-ray tube suspension unit 2 includes a tube position detector 23 that detects the position and angle of the X-ray tube 22, a tube position detector 23, and a leaf position detector 29b described later. And an A / D converter 24 for converting the analog voltage of the position information obtained by the above into digital data. In addition, the X-ray tube suspension unit 2 includes a memory unit 25, an input unit 26 (pointing device 26A, AEC lighting field selection button 26B, X-ray imaging button 26C) and an output unit 27 (display unit 27A, buzzer 27B, warning lamp). 27C), a control unit 28, a collimator 29a, and a leaf position detection unit 29b. The X-ray tube 22 corresponds to the X-ray irradiating means in the present invention, the AEC lighting field selection button 26B corresponds to the lighting field setting means in the present invention, and the control unit 28 includes the lighting field detecting means in the present invention and the non-lighting field detecting means in the present invention. The collimator 29a corresponds to the use setting means, and corresponds to the X-ray diaphragm means in the present invention.

  As shown in FIG. 1, the X-ray imaging stand unit 3 includes a standing stand 31 that supports a subject M in a standing posture, and a flat panel X-ray that is mounted on the standing stand 31 and can be moved up and down. And a detector (FPD) 32. Further, as shown in FIG. 2, the X-ray imaging stand unit 3 converts an FPD position detection unit 33 that detects the position of the FPD 32 and an analog voltage of position information obtained by the FPD position detection unit 33 into digital data. And an A / D converter 34. In addition, the X-ray imaging stand unit 3 includes a memory unit 35 and a control unit 36. Similar to the X-ray tube suspension unit 2, the X-ray imaging stand unit 3 may include an input unit and an output unit. Even if the X-ray imaging stand unit 3 is not provided with the memory unit 35 or the control unit 36, the control unit 28 of the X-ray tube suspension unit 2 may directly control the FPD 32 of the X-ray imaging stand unit 3 or the like. Good. The FPD 32 of the X-ray imaging stand unit 3 and the FPD 42 of the prone position table unit 4 described later correspond to the X-ray detection means in this invention.

  As shown in FIG. 1, the lying table unit 4 includes a lying table 41 on which the subject M is placed in a lying position, and a flat panel X-ray detector that is mounted on the lying table 41 and can move horizontally. (FPD) 42. Further, as shown in FIG. 2, the lying position table unit 4 includes an FPD position detecting unit 43 that detects the position of the FPD 42, and an analog voltage of position information obtained by the FPD position detecting unit 43 that is converted into digital data A / D converter 44. In addition, the lying table unit 4 includes a memory unit 45 and a control unit 46. Similar to the X-ray tube suspension unit 2, the lying table unit 4 may include an input unit and an output unit. Further, the control unit 28 of the X-ray tube suspension unit 2 may directly control the FPD 42 of the position table unit 4 without including the memory unit 45 and the control unit 46 in the position table unit 4.

  As shown in FIG. 2, the image processing unit 5 performs image processing based on the X-ray output signal obtained by the FPD 32 of the X-ray imaging stand unit 3 or the FPD 42 of the lying table unit 4 and performs an X-ray image (X An image processing unit 51 for creating a line image) is provided. In addition, the image processing unit 5 includes a memory unit 52 for writing and storing X-ray images. Similar to the X-ray tube suspension unit 2, the image processing unit 5 may include an input unit and an output unit. Further, the image processing unit 5 may be configured not to include the memory unit 52 but to write and store the X-ray image in the memory unit 25 of the X-ray tube suspension unit 2.

  The column 21 of the X-ray tube suspension unit 2 is movable along a rail R laid along the ceiling. The rail R is laid along the depth direction of the paper surface of FIG. 1, and the support column 21 is movable along the depth direction. The support column 21 is configured to be extendable and retractable, and the X-ray tube 22 is supported by the support column 21 so that the X-ray tube 22 can be moved horizontally and vertically. The direction of the X-ray tube 22 can be adjusted. Accordingly, the X-ray tube 22 is moved up and down as shown in the solid line in FIG. 1 toward the standing stand 31 of the X-ray imaging stand unit 3 to adjust the direction and adjust the X-ray in a standing posture. It is possible to take a picture. Further, the X-ray tube 22 is moved up and down as shown in the two-dot chain line in FIG. It is also possible to perform line photography.

  As shown in FIG. 2, a tube position detector 23 is disposed on the column 21 that supports the X-ray tube 22, and the position and angle of the X-ray tube 22 are detected by the tube position detector 23. The tube position detector 23 is composed of, for example, a potentiometer, and the resistance value of the potentiometer changes with the movement or rotation of the X-ray tube 22, and the output voltage changes with respect to the reference voltage according to the resistance value. This output voltage is an analog voltage, and an analog voltage of position information (including an angle) obtained by the potentiometer is sent to the A / D converter 24. The A / D converter 24 converts the analog voltage into digital data. .

  The memory unit 25 of the X-ray tube suspension unit 2 receives, via the control unit 28, the X-ray tube 22, the collimator 29a, and the X-ray imaging stand unit 3 in addition to the positional information of the sensitivity area of the lighting field (AEC lighting field). The position information of the FPD 32 and the position information of the FPD 42 of the lying position table unit 4 and the position information of the X-ray irradiation region are written and stored, and read out as necessary. In particular, the memory unit 25 includes a relative position information memory unit 25a, in which relative position information between the sensitivity region of the AEC lighting field and the FPD 32 of the X-ray imaging stand unit 3 and the FPD 42 of the lying table unit 4 is written and stored in advance. Yes. By referring to the relative position information based on the position information of the FPDs 32 and 42, the control unit 28 calculates the position information of the sensitivity area of the AEC lighting field, and the position information of the calculated sensitivity area of the AEC lighting field is obtained. Write to the memory unit 25 and store it. The memory unit 25 of the X-ray tube suspension unit 2, the memory unit 35 of the X-ray imaging stand unit 3, the memory unit 45 of the lying table unit 4, and the memory unit 52 of the image processing unit 5 are ROM (Read-only). Memory (RAM), RAM (Random-Access Memory), and other storage media.

  The input unit 26 of the X-ray tube suspension unit 2 sends data and commands input by the operator to the control unit 28. The pointing device 26A of the input unit 26 is a mouse, a keyboard, a joystick, a trackball, a touch panel, or the like. In addition, when there are a plurality of lighting fields (AEC lighting fields) for automatic exposure, the AEC lighting field selection button 26B of the input unit 26 selects which AEC lighting field is to be used. This is a button for setting the AEC lighting field. The operator presses the AEC lighting field selection button 26B to select which AEC lighting field to use. A plurality of AEC lighting fields may be selected. The X-ray imaging button 26C of the input unit 26 is a button for performing an X-ray imaging operation. For example, the X-ray imaging button 26C is composed of a two-stage switch, the tube of the X-ray tube 22 is heated by half-pressing the button lightly, and preparation for X-ray irradiation is made by full-pressing the button deeply.

  The display unit 27A of the output unit 27 of the X-ray tube suspension unit 2 includes a monitor or the like. In addition, the buzzer 27B of the output unit 27 is configured to warn by sound, and the warning lamp 27C of the output unit 27 is configured to perform warning by light. Alternatively, the display unit 27A may be configured by a touch panel on which the above-described AEC lighting field selection button 26B is mounted, and the touch panel may be attached to the X-ray tube 22. As described above, the function of the input unit 26 may be mounted on the output unit 27.

  The control unit 28 of the X-ray tube suspension unit 2 performs overall control of each part constituting the X-ray tube suspension unit 2. The control unit 28 of the X-ray tube suspension unit 2, the control unit 36 of the X-ray imaging stand unit 3, the control unit 46 of the lying table unit 4, and the image processing unit 51 of the image processing unit 5 are a central processing unit. (CPU) and the like. In Example 1, including Example 2 described later, the control unit 28 has a function of performing automatic exposure control regarding the X-ray image processed by the image processing unit 51. Further, in the first embodiment, based on the positional information of the X-ray irradiation region and the sensitivity region of the AEC lighting field, the lighting for detecting the presence or absence of the AEC lighting field in which all the sensitivity regions are not included in the X-ray irradiation region. The control unit 28 controls the function of the field detection means, and further, the function of the unused setting means for setting the corresponding AEC lighting field to be unused when there are one or more AEC lighting fields not included in the X-ray irradiation region. Has.

  The collimator 29 a of the X-ray tube suspension unit 2 is configured to limit the area irradiated by the X-ray tube 22. Specifically, the collimator 29a is configured by four leaves (not shown) arranged vertically and horizontally, and by adjusting each leaf vertically and horizontally, a rectangular X-ray irradiation field (of the X-ray field) Size). The collimator 29a is provided with a leaf position detection unit 29b, and the leaf position detection unit 29b detects the leaf position and opening degree information of the collimator 29a (the size of the opening surrounded by the four leaves). Similar to the tube position detection unit 23 of the X-ray tube suspension unit 2, the leaf position detection unit 29b is also composed of a potentiometer, and the resistance value of the potentiometer changes with the movement of the leaf, and the reference voltage increases with the resistance value. Changes the output voltage. This output voltage is an analog voltage, and the analog voltage of the position information obtained by the potentiometer is sent to the A / D converter 24. The A / D converter 24 converts the analog voltage into digital data. As described in the “Background Art” section, an illumination field lamp (not shown) is built in the casing of the collimator 29a so that the illumination field of light can be confirmed before X-ray imaging. Good.

  As shown in FIG. 1, the standing stand 31 of the X-ray imaging stand unit 3 is installed on the floor surface. The FPD 32 of the X-ray imaging stand unit 3 can be moved up and down along the standing stand 31. On the other hand, the supine table 41 of the supine table unit 4 is also installed with respect to the floor surface. The FPD 42 of the lying table unit 4 can move horizontally within the lying table 41.

  In Example 1, including Example 2 described later, the FPD 32 of the X-ray imaging stand unit 3 and the FPD 42 of the lying table unit 4 also serve as an AEC detection unit. That is, when an X-ray image is acquired by the FPD 32 of the X-ray imaging stand unit 3 or the FPD 42 of the lying table unit 4, the X-rays detected in the FPD area matching the AEC lighting field are converted into electrical signals (X-ray output). Signal), and X-ray irradiation is interrupted when the integrated value of the electrical signal (X-ray output signal) reaches an appropriate value. Thus, automatic exposure (AEC) is performed by the FPD.

  As shown in FIG. 2, an FPD position detector 33 is disposed in the FPD 32 of the X-ray imaging stand unit 3, and the FPD position detector 33 detects the position of the FPD 32. On the other hand, an FPD position detector 43 is also provided in the FPD 42 of the lying table unit 4, and the FPD position detector 43 detects the position of the FPD 42. Similar to the FPD position detector 23 and leaf position detector 29b of the X-ray tube suspension unit 2, the FPD position detector 33 of the X-ray imaging stand unit 3 and the FPD position detector 43 of the lying table unit 4 are also potentiometers. The resistance value of the potentiometer changes with the movement of the FPDs 32 and 42, and the output voltage changes with respect to the reference voltage according to the resistance value. This output voltage is an analog voltage, and the analog voltage of the position information obtained by the potentiometer is sent to the A / D converter 34 in the case of the X-ray imaging stand unit 3, and in the case of the position table unit 4. The A / D converters 34 and 44 convert the analog voltages into digital data. Further, the analog voltage of the position information obtained by the potentiometer of the X-ray imaging stand unit 3 or the lying table unit 4 is also sent to the X-ray tube suspension unit 2 via the communication cable 6.

  The memory unit 35 of the X-ray imaging stand unit 3 writes and stores the upper end position and the lower end position of the FPD 32 in X-ray imaging, and reads them out as necessary. On the other hand, the memory unit 45 of the prone position table unit 4 writes and stores the left end position and the right end position of the FPD 42 in X-ray imaging, and reads them out as necessary.

  The control unit 36 of the X-ray imaging stand unit 3 controls each part constituting the X-ray imaging stand unit 3, and the control part 46 of the lying table unit 4 controls each part constituting the lying table unit 4. Take overall control.

  The control unit 28 of the X-ray tube suspension unit 2 and the control unit 36 of the X-ray imaging stand unit 3 are electrically connected by the communication cable 6, and the control unit 28 of the X-ray tube suspension unit 2 and the prone table The control unit 46 of the unit 4 is electrically connected by the communication cable 6, and the control unit 28 of the X-ray tube suspension unit 2 and the image processing unit 51 of the image processing unit 5 are electrically connected by the communication cable 6. Connecting. By connecting in this way, the X-ray tube suspension unit 2, the X-ray imaging stand unit 3, the lying table unit 4 and the image processing unit 5 are configured to be able to communicate with each other. In addition, the control units 28, 36, and 46 drive and control the X-ray tube 22 and the FPDs 32 and 42, and the control units 28, 36, and 46 control the motor (not shown) to control the X-ray tube 22 and the FPDs 32 and 42. The FPDs 32 and 42 are driven by a motor. By driving the motor, the X-ray tube 22 and the FPDs 32 and 42 can be controlled to desired positions, and the direction of the X-ray tube 22 can be adjusted at a desired angle.

  Next, the setting (selection) of the AEC lighting field, the detection of the AEC lighting field, and the unused setting of the AEC lighting field will be described with reference to FIGS. FIG. 3 is a schematic diagram of the position of the AEC lighting field, and FIG. 4 is a schematic diagram of the AEC lighting field and the X-ray irradiation area. 3 and 4, an explanation will be given by taking X-ray imaging on an upright stand 31 (see FIGS. 1 and 2, not shown in FIGS. 3 and 4) as an example.

  First, the relative position information between the sensitivity region of the AEC lighting field and the FPD 32 (see FIG. 1) installed along the standing stand 31 is used as the relative position information memory unit 25a of the X-ray tube suspension unit 2 (see FIG. 2). ) In advance and stored. In the case where the FPD 32 also serves as the AEC detector as in the first embodiment including the second embodiment described later, it is not always necessary to store the relative position information between the sensitivity region of the AEC lighting field and the FPD 32 in advance. Absent.

The operator presses the AEC lighting field selection button 26B (see FIG. 2) of the X-ray tube suspension unit 2. For example, as shown in FIG. 3, the position of the center of the detection field and V _C, the position of the left side of the detection field and V _L, the position of the right detection field and V _R. The operator presses the AEC lighting field selection button 26B, and selects which AEC lighting field (lighting fields V _C , V _L , V _{R in} FIG. 3) is to be used. Information on the selected AEC lighting field is sent to the control unit 28 (see FIG. 2) of the X-ray tube suspension unit 2. It should be noted that the left and right are not viewed from the operator, but are viewed from the subject M (see FIG. 1).

The control unit 28 detects the position information of the X-ray tube 22 (see FIG. 1) obtained by the tube position detection unit 23 (see FIG. 2) of the X-ray tube suspension unit 2, and the leaf of the X-ray tube suspension unit 2. Position information of the collimator 29a (see FIG. 2) obtained by the position detector 29b (see FIG. 2) and the FPD 32 obtained by the FPD position detector 33 (see FIG. 2) of the X-ray imaging stand unit 3 based on the position information calculates the position information of the X-ray irradiated area V _I shown in FIG. Thus, X-rays irradiated area V _I is calculated whether is set by irradiation with respect to the position of the throat FPD 32.

The control unit 28 refers to the relative position information memory unit 25a that stores the relative position information between the sensitivity region of the AEC lighting field and the FPD 32, and the current position of the FPD 32 (obtained by the FPD position detection unit 33). By referring to the relative position information based on the information, the position information of the sensitivity region of the AEC lighting field is calculated. Further, the control unit 28, the AEC detection field set by AEC detection field selection button 26B, the position information of the X-ray irradiated area V _I calculated based on the position information of FPD32 as described above, of the as the sensitivity region of the AEC detection field which is calculated based on the position information of the FPD 32 (in FIGS. 3 and 4 detection field _{V C, V L, V R} ) referring to the position information of.

Thus, in the AEC detection field set by AEC detection field selection button 26B, based on the position information of the sensitivity range of the X-ray irradiated area V _I and AEC detection field, all the region X-ray irradiated area V of the sensitive region The presence or absence of an AEC lighting field not included in _I is detected. In Figure 4, all the region of the center of the AEC detection field _{V C} and left AEC detection field _{V L} in the sensitivity region is included in the X-ray irradiated area _{V I,} right AEC detection field _{V R} only sensitive area some of are not included in the X-ray irradiation area V _I. Thus, in FIG. 4, on the basis of the position information of the sensitivity range of the X-ray irradiated area V _I and AEC detection field, control the AEC detection field V _R which all the regions are not included in the X-ray irradiated area V _I of the sensitive region The unit 28 detects.

If AEC detection field where all the regions are not included in the X-ray irradiated area V _I of the sensitive region there is at least one, the controller 28 sets the unused appropriate AEC detection field. In Figure 4, all the regions of the sensitive region is set to unused AEC detection field V _R which is not included in the X-ray irradiated area V _I.

  According to the X-ray imaging apparatus according to the first embodiment having the above-described configuration, when there are a plurality of AEC lighting fields for automatic exposure as in the first embodiment, an X-ray irradiation area and an AEC lighting field are provided. Based on the position information of the sensitivity region, the control unit 28 detects the presence or absence of an AEC lighting field in which all the sensitivity regions are not included in the X-ray irradiation region. The sensitivity area is reduced in the AEC lighting field that is not included in the X-ray irradiation area, and there is one or more AEC lighting fields that are not included in the X-ray irradiation area (that is, the AEC lighting field in which the sensitivity area is decreased). If so, the control unit 28 sets the corresponding AEC lighting field to unused. Then, an AEC lighting field other than the unused AEC lighting field is selected and set from the AEC lighting fields set (selected) by the AEC lighting field selection button 26B. If automatic exposure control and X-ray imaging control are performed using the remaining AEC field without using the AEC field where the sensitivity region is reduced in this way, the X-ray output is blocked in the remaining AEC field. The X-ray output is cut off at a predetermined value determined in advance for the total incident X-ray dose. Therefore, appropriate automatic exposure control, and hence appropriate X-ray imaging control can be performed, and the density (pixel value) of the X-ray imaging image (X-ray image) obtained by imaging is constant. Further, it is not necessary to accurately obtain the X-ray irradiation region by the scattered radiation of the subject M, and as described in the section of “Means for Solving the Problem”, as disclosed in Patent Document 1: Japanese Patent No. 5344807 There is no need for correction, and no multiplier is required. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.

  In the first embodiment, a collimator 29a for limiting the region irradiated by the X-ray tube 22 is provided, and positional information of the X-ray irradiation region is obtained by using the X-ray tube 22, the collimator 29a, and (X-rays transmitted through the subject M). It is calculated based on the position information of each flat panel X-ray detector (FPD) (FPD 32 in the case of X-ray imaging with the standing stand 31). In this way, the position of the FPD 32 where the X-ray irradiation area is set is calculated. Then, the X-ray irradiation area is subjected to detection of the presence or absence of an AEC lighting field (not included in the X-ray irradiation area) by the control unit 28.

The first embodiment also includes a relative position information memory unit 25a that stores relative position information between the sensitivity region of the AEC daylighting field and the FPD (FPD 32 in the case of X-ray imaging with the standing stand 31). By referring to the relative position information based on the position information, the position information of the sensitivity region of the AEC lighting field is calculated. In this way, the relative position information is referred to based on the position information of the FPD 32, the position information of the sensitivity area of the AEC lighting field is calculated, and the X-ray irradiation area is included in the control unit 28 (included in the X-ray irradiation area). No) Use for detection of presence or absence of AEC lighting field.

Next, Embodiment 2 of the present invention will be described with reference to the drawings.
In the second embodiment, including the block diagram of FIG. 2, X-ray imaging is performed using the X-ray imaging apparatus 1 shown in FIG.

  In the first embodiment described above, the X-ray imaging button 26C, the buzzer 27B, and the warning lamp 27C are provided. In the second embodiment, the functions of the X-ray imaging button 26C, the buzzer 27B, and the warning lamp 27C are also described in detail. explain. In FIG. 2, the display unit 27A, the buzzer 27B, and the warning lamp 27C are illustrated as separate components, but it should be noted that the display unit 27A actually includes the buzzer 27B and the warning lamp 27C. I want to be. Of course, the display unit 27A, the buzzer 27B, and the warning lamp 27C may have different configurations. The buzzer 27B and the warning lamp 27C in the second embodiment correspond to warning means in the present invention.

  In the second embodiment, based on the positional information of the X-ray irradiation area and the sensitivity area of the AEC lighting field (for automatic exposure), all the sensitivity areas are not included in the X-ray irradiation area. The control unit 28 has a function of the daylighting field detecting means for detecting the presence or absence. The control unit 28 in the second embodiment corresponds to the lighting field detecting means in the present invention.

Similar to the above-described first embodiment, in the second embodiment, the control unit 28 determines the position information of each of the X-ray tube 22, the collimator 29a, and the FPD (FPD 32 in the case of X-ray imaging with the standing stand 31). based on, it is calculated (see FIG. 4) position information of the X-ray irradiated area V _I. Thus, X-rays irradiated area V _I is calculated whether is set by irradiation with respect to the position of the throat FPD 32.

Similarly to the first embodiment described above, in the second embodiment, the relative position information for storing the relative position information between the sensitivity region of the AEC lighting field and the FPD (FPD 32 in the case of X-ray imaging with the standing stand 31) is stored. A position information memory unit 25a is provided, and the control unit 28 refers to the relative position information based on the position information of the FPD 32, thereby calculating the position information of the sensitivity region of the AEC lighting field. Further, the control unit 28 based on the position information of the sensitivity range of the X-ray irradiated area V _I and AEC detection field, the presence of all the regions are not included in the X-ray irradiated area V _I AEC detection field sensitivity region To detect.

In Embodiment 2, if not included in the X-ray irradiated area V _I AEC detection field is present, the control unit 28 outputs the X-ray irradiation area disagreement information display unit 27A the X-ray irradiated region inconsistency information To send. When the display unit 27A receives the X-ray irradiation area mismatch information, the display unit 27A issues a warning with sound by the buzzer 27B, or issues a warning with light by the warning lamp 27C. Note that a warning may be issued by displaying an error message on the display unit 27A.

  Although the display unit 27A is configured to issue a warning at the timing when the X-ray irradiation region mismatch information is received, the warning may be issued at the timing when the X-ray imaging operation is performed by the operator. For example, a warning may be issued when the operator presses the X-ray imaging button 26C. In this case, a warning may be issued when the tube of the X-ray tube 22 is heated by half-pressing the X-ray imaging button 26C, or preparation for X-ray irradiation is performed by fully pressing the X-ray imaging button 26C. A warning may be issued at the timing. That is, for example, only the detection flag is set when the X-ray irradiation region mismatch information is received, and a warning is issued based on the detection flag when the X-ray imaging button 26C is pressed. When a warning is issued at the timing when preparation for X-ray irradiation is performed by fully pressing the X-ray imaging button 26 </ b> C, X-rays are not irradiated from the X-ray tube 22.

  As described above, in the first embodiment described above, there are a plurality of AEC lighting fields. However, in the second embodiment, the present invention can also be applied to a case where there is only one AEC lighting field. In the first embodiment, warning means such as the buzzer 27B and the warning lamp 27C are not essential, and in this embodiment 2, warning means such as the buzzer 27B and the warning lamp 27C are essential. As with the first embodiment described above, according to the X-ray imaging apparatus according to the second embodiment, all the sensitivity regions are irradiated with X-rays based on the positional information of the X-ray irradiation region and the sensitivity region of the AEC lighting field. The control unit 28 detects the presence / absence of an AEC lighting field not included in the region. As described in the operation and effect of the first embodiment described above, the sensitivity region is reduced in the AEC lighting field that is not included in the X-ray irradiation region. In the second embodiment, when there is an AEC lighting field that is not included in the X-ray irradiation area (that is, an AEC lighting field in which the sensitivity area is reduced), warning means such as the buzzer 27B and the warning lamp 27C described above are warned. To emit. If the warning is given to the operator by the warning means before the X-ray imaging, it can be seen that the X-ray irradiation area is deviated or missing from the sensitivity area of the AEC lighting field before the X-ray imaging. Therefore, the operator adjusts the position of the subject M and the X-ray irradiation area again, so that an appropriate X-ray total incident dose is incident on the AEC lighting field. Appropriate X-ray imaging control can be performed, and the density (pixel value) of an X-ray imaging image (X-ray image) obtained by imaging is constant. At this time, since the operator can recognize in advance that the imaging positioning is different from the normal, it is possible to correct if there is a mistake in the imaging positioning, and an X-ray image (X-ray image) can be corrected. ) Output and display position does not change. Further, the X-ray output signal from the AEC lighting field is the same as the conventional one by adjusting again, and a multiplier as in Patent Document 1: Japanese Patent No. 5344807 is not required. As a result, with a simple structure, automatic exposure control can be appropriately performed and X-ray imaging control can be appropriately performed.

  As described above, the warning means may issue a warning with light using, for example, the warning lamp 27C, or may give a warning with sound using, for example, the buzzer 27B. Moreover, you may warn combining both light and a sound. For example, the warning may always be performed with light (red light indicating a warning), and the warning may be performed with sound at a stage before X-ray imaging.

  Further, as described above, the warning unit may issue a warning at the timing when the X-ray imaging operation is performed by pressing the X-ray imaging button 26C, for example. That is, when there is an AEC lighting field that is not included in the X-ray irradiation area, the warning means does not issue a warning at that time (for example, when the X-ray irradiation area mismatch information is received), and is detected by the lighting field detection means. Only the flag is set and a warning is given based on the detection flag at the timing when the X-ray imaging operation is performed (for example, the timing when the X-ray imaging button 26C is pressed). Also in this case, the warning means may give a warning with light using, for example, the warning lamp 27C, or may give a warning with sound using, for example, the buzzer 27B.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, the X-ray imaging apparatus is an apparatus as shown in FIG. 1. However, if the apparatus performs X-ray imaging, the apparatus performs X-ray imaging only in a standing posture. It may also be an apparatus that performs X-ray imaging of only the supine posture. Moreover, the apparatus which performs the X-ray imaging provided with the tiltable table which can apply both a standing posture and a supine posture may be sufficient.

  (2) In each of the above-described embodiments, the flat panel detector (FPD) also serves as the AEC detection unit. However, the AEC detection unit is configured by a photosensor tube such as a phototimer, and the AEC is closer to the incident side than the FPD. You may install a detection part. When the AEC detection unit is installed on the incident side of the FPD, in order to accurately obtain the position information of the sensitivity area of the AEC lighting field, the relative position information of the sensitivity area of the AEC lighting field and the FPD is stored in advance. It is preferable to calculate the position information of the sensitivity region of the AEC lighting field by referring to the relative position information based on the position information of the FPD.

  (3) In each of the above-described embodiments, a flat panel X-ray detector has been described as an example of the X-ray detection means. However, as the X-ray detection means, for example, an X-ray film or CR is usually used. If it is used in, it will not specifically limit.

  (4) You may combine Example 1 and Example 2 which were mentioned above. In the case where there are a plurality of AEC lighting fields as in the first embodiment described above and there are one or more AEC lighting fields not included in the X-ray irradiation area, when the corresponding AEC lighting field is set to be unused. Alternatively, a warning may be given to the operator prior to X-ray imaging by warning means (for example, buzzer 27B or warning lamp 27C). Then, the operator again adjusts the position of the subject and the X-ray irradiation area so that an appropriate X-ray total incident dose is incident on the AEC lighting field set to unused, and sets it to unused. Set the AEC lighting field to be usable.

  (5) In the first embodiment described above, AEC lighting fields other than the AEC lighting fields set to unused are selected from the AEC lighting fields set (selected) by the lighting field setting means (AEC lighting field selection button 26B in FIG. 2). Although the field is selected and set, it is not always necessary to configure the lighting field setting means with an input unit represented by an AEC lighting field selection button or the like. For example, the daylight field setting means may be constituted by a central processing unit (CPU) or the like, and the daylight field setting means may select and set an AEC daylight field other than the unused AEC daylight field. That is, the daylighting field setting means may also serve as the unused setting means.

DESCRIPTION OF SYMBOLS 1 ... X-ray imaging apparatus 22 ... X-ray tube 25a ... Relative position information memory part 26B ... AEC lighting field selection button 27B ... Warning lamp 27C ... Buzzer 28 ... Control part 29a ... Collimator 32, 42 ... Flat panel type X-ray detector (FPD)
V _C , V _L , V _R ... Lighting field (AEC lighting field)
V _I ... X-ray irradiation area M ... Subject

Claims (8)

An X-ray imaging apparatus that performs X-ray imaging,
X-ray irradiation means for irradiating the subject with X-rays;
There are a plurality of daylight fields for automatic exposure, and a daylight field setting means for selecting which daylight field to use and setting the selected daylight field,
Based on the positional information of the X-ray irradiation area irradiated by the X-ray irradiation means and the sensitivity field of the lighting field, the lighting for detecting the presence or absence of the lighting field in which all the sensitivity areas are not included in the X-ray irradiation area Field detection means;
An X-ray imaging apparatus comprising: an unused setting unit that sets the corresponding lighting field to unused when there is one or more lighting fields not included in the X-ray irradiation region. An X-ray imaging apparatus that performs X-ray imaging,
X-ray irradiation means for irradiating the subject with X-rays;
Based on the position information of the X-ray irradiation area irradiated by the X-ray irradiation means and the sensitivity area of the lighting field for automatic exposure, all the areas of the sensitivity area are not included in the X-ray irradiation area. Lighting field detecting means for detecting presence or absence;
An X-ray imaging apparatus comprising: a warning unit that issues a warning when there is a lighting field that is not included in the X-ray irradiation region. The X-ray imaging apparatus according to claim 1,
An X-ray imaging apparatus comprising warning means for issuing a warning when the lighting field not included in the X-ray irradiation region exists. The X-ray imaging apparatus according to claim 2 or 3,
The X-ray imaging apparatus characterized in that the warning means issues a warning with light. The X-ray imaging apparatus according to any one of claims 2 to 4,
The X-ray imaging apparatus characterized in that the warning means issues a warning by sound. The X-ray imaging apparatus according to any one of claims 2 to 5,
The X-ray imaging apparatus characterized in that the warning means issues a warning at a timing when an X-ray imaging operation is performed. The X-ray imaging apparatus according to any one of claims 1 to 6,
X-ray diaphragm means for limiting the area irradiated by the X-ray irradiation means;
X-ray detection means for detecting X-rays transmitted through the subject,
An X-ray imaging apparatus characterized in that position information of the X-ray irradiation area is calculated based on position information of the X-ray irradiation means, the X-ray diaphragm means, and the X-ray detection means. The X-ray imaging apparatus according to any one of claims 1 to 7,
X-ray detection means for detecting X-rays transmitted through the subject;
Relative position information storage means for storing relative position information between the sensitivity field of the lighting field and the X-ray detection means,
An X-ray imaging apparatus that calculates position information of a sensitivity region of the daylighting field by referring to the relative position information based on position information of the X-ray detection means.

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