JP2018201875A - Radiographic apparatus, radiographic system, radiographic method, and program - Google Patents

Abstract

To provide a radiographic apparatus capable of suppressing unnecessary exposure and the effect of scattered radiation caused by irradiating a range wider than a predetermined range.SOLUTION: The radiographic apparatus comprises: imaging means including plural pixel sensors for detecting radiation; irradiation detection means which detects radiation applied to a second pixel sensor other than a first pixel sensor used to generate a radiation image, out of the plural pixel sensors; and reporting means which reports that the radiation is applied to the second pixel sensor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation imaging apparatus, a radiation imaging system, a radiation imaging method, and a program.

  In a conventional radiographic apparatus, a radiation beam is projected from a radiation source, and after the radiation beam passes through a subject, a radiation image is imaged and output. The imaging method was film or CR (Computer Radiography), but in recent years, the number of images taken by FPD (Flat Panel Detector) has been increasing. Digitalization of medical images is progressing rapidly as well as consumer devices.

  In particular, since the introduction of FPD, the market for FPD has expanded year by year in terms of image quality and immediacy. The FPD uses a photoelectric conversion device in which pixels (pixel sensors) including minute photoelectric conversion elements or switching elements using a semiconductor as an image receiving means are arranged in a grid pattern, and acquires a digital image. As a trend in recent years, FPDs are becoming lighter and more portable. For this reason, installation according to various imaging methods other than stationary built-in is possible with a lightweight cassette type FPD.

  The FPD is significantly different from the conventional film and CR in the structure in the photographing unit, such that an electric substrate for reading an image signal may be necessary due to the structure. In particular, in a small cassette type FPD, an electric substrate and a battery in the internal structure of the FPD imaging unit are often arranged on the back surface of the photoelectric conversion element in the imaging unit.

  The cassette type FPD is not only reduced in weight, but also wireless, and can be installed in a free arrangement separately from the radiation generation apparatus. Therefore, there is a possibility that the radiation is irradiated wider than the imaging region. In setting the irradiation field, it is common to use a radiation shielding mechanism called a collimator of a radiation generator.

JP 11-318877 A Japanese Patent No. 5341463 Japanese Patent No. 3631095

Alisa Walz-Flannigan, Dayne Magnuson, Daniel Erickson, Beth Schueler, “Artifacts in Digital Radiography”, AJR January 2012, Volume 198, Number 1.

  However, the FPD may be moved after adjusting the collimator to set the irradiation field. Further, even if the collimator is adjusted, the adjusted irradiation field may not match the actual radiation irradiation field. In these cases, there is a possibility that the radiation is irradiated to the outside of the desired imaging region of the radiation imaging apparatus (for example, outside the effective pixel). Further, when radiation is irradiated to the outside of the effective pixels of the radiation imaging apparatus, the radiation may be scattered by a wall or the like and may enter from the back of the radiation imaging apparatus, and the FPD internal structure may be reflected in the image.

  In Patent Literature 1, Patent Literature 2, and Patent Literature 3, no consideration is given to the influence of reflection of an electronic board or the like due to radiation backscattering or a battery. For this reason, unnecessary objects may appear in the image due to the influence of backscattering due to the wide radiation range. Thus, in the related art, there is a problem that no warning is given about the influence of backscattering when the radiation irradiation range is wide.

  The radiation imaging apparatus of the present invention includes an imaging unit including a plurality of pixel sensors for detecting radiation, and a second pixel other than the first pixel sensor used for generating a radiation image among the plurality of pixel sensors. Irradiation detecting means for detecting radiation irradiated to the sensor, and notification means for notifying that the second pixel sensor has been irradiated with the radiation.

  According to the present invention, it is possible to suppress the effects of unnecessary exposure and scattered radiation caused by irradiation of radiation wider than a predetermined range.

It is a figure which shows the structure of the radiography apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the process which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the adjustment process of the threshold value which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of an imaging | photography part and a radiation irradiation range. It is a figure which shows the example by which the radiation was imaged. It is a figure which shows the 1st example of the notification which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of the radiographic image corresponding to a 1st example. It is a figure which shows the 2nd example of the notification which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of the radiographic image corresponding to a 2nd example. It is a figure explaining the influence of a scattered ray. It is a figure which shows the structure of the radiography apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the process which concerns on the 2nd Embodiment of this invention.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the following, as an embodiment of the present invention, a case will be described in which the present invention is applied to a radiation imaging apparatus that captures radiographic image data of a subject using X-rays that are a kind of radiation. However, the present invention is not limited to the radiographic apparatus described below, and, for example, radiographic imaging that captures radiographic image data of a subject using other radiation (for example, α rays, β rays, and γ rays). It is also possible to apply to an apparatus.

(First embodiment)

  Hereinafter, a first embodiment for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a radiation imaging apparatus 1000 according to the first embodiment of the present invention. The radiation imaging apparatus 1000 according to the present embodiment is used particularly for medical purposes. A medical worker sets an imaging unit 1004 including a radiation irradiation unit 1001 and a two-dimensional planar pixel sensor through an operation panel 1016 using an information device having a CPU 1014 and a memory 1015. The radiation irradiation unit 1001 irradiates the subject 1003 with the radiation 1002.

  The imaging unit 1004 detects radiation incident through the subject 1003 and generates radiation image data. The radiation irradiation unit 1001 includes a radiation generation unit (tube) that generates radiation, and a collimator that defines a beam divergence angle of the radiation generated in the radiation generation unit.

  The control unit 1005 controls the radiation dose irradiated from the radiation irradiation unit 1001. After determining the position of the subject 1003, the medical worker who operates operates a collimator (not shown) to instruct a range where the imaging unit 1004 is irradiated with the radiation 1002. When the portable FPD is not fixed, it may be necessary to adjust the alignment for each photographing.

  In general, the collimator has a bellows shape, and can be opened and closed by a combination of a plurality of metal plates, so that the radiation irradiation field can be adjusted. Although the radiation field is adjusted based on the guide by visible light reflected by the mirror, there may be a difference between the guide and the actual radiation field due to an error or the arrangement of the portable FPD.

  In the present embodiment, by analyzing the output value of each pixel of the imaging unit 1004, the notification unit 1019 notifies a warning when the irradiation field is irradiated to a pixel outside the effective pixel range.

  In the imaging unit 1004, there is a flat detector in which a large number of pixels (pixel sensors) are arranged on a semiconductor wafer. The flat panel detector includes a pixel (first pixel sensor) 1009 within the effective pixel range and a pixel (second pixel sensor) 1008 outside the effective pixel range. That is, the imaging unit 1004 includes a plurality of pixel sensors that detect radiation.

  The radiation 1002 irradiated to the imaging unit 1004 may be irradiated not only to the pixel 1009 within the effective pixel range but also to the pixel 1008 outside the effective pixel range. The pixel 1008 outside the effective pixel range includes invalid pixels. The invalid pixels may include pixels for performing automatic exposure control (AEC).

  The pixel 1009 is used for generating a radiation image as an effective pixel. The pixel 1008 is not used to generate a radiation image as an invalid pixel.

  When the radiation 1002 is irradiated more widely than the imaging unit 1004, the object 1003 is not only irradiated with radiation that is not imaged. When radiation is applied to the rear wall or the like, scattered radiation is generated. When the scattered radiation is transmitted through the electric substrate 1010 and then irradiated to the pixel 1009 within the effective pixel range through a phosphor or the like, the imaging unit 1004 May be reflected in the image.

  The captured image is sent to the data collection unit 1006. The collected data (image data) is pre-processed by the pre-processing unit 1007 and the image processing unit 1013 performs display image processing. An irradiation range determination unit (irradiation detection unit) 1018 determines whether or not radiation is irradiated outside the effective pixel range or the imaging region.

  An irradiation range determination unit (irradiation detection unit) 1018 detects radiation irradiated to second pixels 1008 other than the first pixel sensor used to generate a radiation image among the plurality of pixel sensors. Further, the irradiation range determination unit 1018 may detect radiation irradiated to the pixels 1009 other than the imaging region among the pixels 1009.

  The subject determination unit 1022 determines whether a subject exists in the radiation field outside the effective pixel range, and acquires subject information. The structure determination unit 1023 determines whether the internal structure of the photographing unit 1004 is reflected in the image.

  The image data of each pixel is determined by the irradiation range determination unit 1018 comparing with the threshold value based on the determination results of the subject determination unit 1022 and the structure determination unit 1023. The irradiation range determination unit 1018 sets a predetermined threshold based on the radiographic image capturing condition, and detects radiation when the amount of radiation irradiated to the pixel sensor exceeds the threshold.

  The notification unit 1019 notifies based on the results of the irradiation range determination unit 1018, the subject determination unit 1022, and the structure determination unit 1023. For example, the notification unit 1019 notifies that the pixel 1008 has been irradiated with radiation. The image data finally becomes a diagnostic image and is displayed on the image display 1017.

  FIG. 2 is a flowchart illustrating processing according to the present embodiment. With reference to FIG. 2, processing will be described in which subject shooting is performed and the notification unit 1019 notifies based on the results of the irradiation range determination unit 1018, the subject determination unit 1022, and the structure determination unit 1023.

  In step S201, image acquisition is started. A photographer (for example, a medical worker) sets photographing conditions based on the photographing purpose, the subject thickness, and the specifications of the photographing unit to be used.

  In step S202, the subject 1003 is positioned. When the region to be imaged is irradiated with radiation, the subject 1003 is positioned so that an intended image is obtained.

  In step S203, the amount of aperture of radiation is set. The photographer sets the amount of aperture of the radiation so that the portion of the image that needs to be captured is irradiated with the radiation. However, although the radiation field is set based on a guide by visible light corresponding to the aperture of the collimator, the actual radiation field and the visible light are often slightly shifted. Further, the cassette type FPD may move after positioning the subject 1003 and setting the aperture amount. That is, radiation may be emitted outside the set range.

  In the present embodiment, the notification unit 1019 issues a warning when radiation is emitted outside the effective pixels of the imaging unit 1004. For example, the notification unit 1019 performs notification so that the radiation irradiated to the pixel 1008 is limited by a collimator or the like.

  In step S204, radiography is performed. Note that the warning by the notification unit 1019 may be performed not only after radiation imaging but also during radiation imaging by reading pre-exposure before actual radiation imaging or reading out a pixel output signal during radiation irradiation. . In this case, the irradiation range determination unit 1018 sets the threshold value by pre-irradiation for irradiating radiation before capturing a radiation image or by irradiation with radiation during capturing of a radiation image.

  In step S205, calculation is performed using pixel values of pixels within the effective pixel range (effective pixels) and pixels outside the effective pixel range (invalid pixels and AEC pixels). In addition, calculation is performed using pixel values of pixels at a predetermined distance or range from the outer edge of the effective pixel range or a part thereof (outer edge pixel).

  If it is determined in step S206 that the radiation irradiation region (radiation irradiation field) does not exceed the effective pixel range, the process proceeds to step S212 to prepare for the next radiation imaging.

  In step S206, when the radiation irradiation region (radiation irradiation field) exceeds the effective pixel range, the notification unit 1019 notifies the warning and proceeds to step S207.

  In step S207, the position of the radiation irradiation region exceeding the effective pixel range is specified by calculating using the result of step S205. The irradiation range determination unit 1018 determines whether or not radiation is irradiated outside the effective pixel range, and specifies the position. Details will be described later.

  In step S208, the subject determination unit 1022 determines whether or not the subject 1003 exists in the radiation irradiation field outside the effective pixel range. The subject determination unit 1022 determines the presence or absence of a subject at the position of the pixel 1008 outside the effective pixel range irradiated with radiation. When the subject 1003 does not exist in the radiation field outside the effective pixel range, the radiation is not attenuated and the influence of the scattered radiation is increased. Therefore, it is necessary to actively narrow the radiation irradiation range. That is, it is necessary to adjust the irradiation field stop mechanism (collimator) so that the radiation is not irradiated outside the effective pixel range.

  On the other hand, generally, the transmittance of radiation in a subject such as a human body is 1/10 or less, the radiation is attenuated, and the influence of scattered radiation is small. Therefore, when the subject 1003 exists in the radiation field outside the effective pixel range, There is no need to actively narrow down the range of irradiation.

  For example, when the subject 1003 does not exist in the radiation field outside the effective pixel range, the radiation dose is large, and thus scattered rays generated on the wall behind the imaging unit 1004 enter from the rear of the imaging unit 1004 and have an influence. give.

  In step S209, the structure determination unit 1023 determines whether the internal structure of the photographing unit 1004 is reflected in the image. Even if radiation is irradiated outside the effective pixel range, if the structure of the imaging unit 1004 is a uniform region, the structure is not reflected as an image by scattered rays incident from behind. In this case, the image density may change due to the incidence of scattered radiation, but the influence of scattered radiation is small because the image density can be adjusted by image processing. On the other hand, the electric board 1010, the battery, and the like are reflected in the radiation image due to the scattered rays that pass through the structure of the imaging unit 1004 such as the electric board 1010, the battery, etc., which are not uniform. Details will be described later.

  In addition to the present embodiment, the structure determination unit 1023 may determine the intensity or direction of the scattered radiation of the radiation transmitted through the second pixel sensor 1008, the distance between the second image sensor 1008 and the predetermined structure of the imaging unit 1004, or Depending on the direction, the distance or direction between the scattered position of the scattered radiation and the predetermined structure of the imaging unit 1004, and the predetermined structure of the imaging unit 1004, the predetermined structure of the imaging unit 1004 is a radiation image due to scattered radiation. The degree of reflection in the image may be determined.

  In step S210, the position of the radiation irradiation region exceeding the effective pixel range is displayed. Further, based on the determination whether the subject exists in the radiation field outside the effective pixel range or whether the internal structure of the imaging unit 1004 is reflected in the image, each determination result and the determination result are determined. The influence degree of the scattered radiation or the necessity degree of adjusting the radiation irradiation area is displayed. When the radiation irradiation region (radiation irradiation field) exceeds the effective pixel range, the notification unit 1019 promptly notifies a warning in step S206.

  In step S211, the radiation irradiation area is adjusted as necessary, and the process proceeds to step S212.

  FIG. 3 is a flowchart illustrating each determination process according to the present embodiment. In step S401, irradiation is performed. The radiation 1002 irradiated from the radiation irradiation unit 1001 passes through the subject 1003 and is irradiated to the imaging unit 1004.

  In step S402, the pixel area is divided. The pixel area refers to a pixel area of the imaging unit 1004. The pixel area is divided into a pixel 1008 outside the effective pixel range and a pixel 1009 within the effective pixel range. The effective pixel is a pixel that is output as an image, and is a pixel that is actually used to generate a radiation image. The effective pixel range in the imaging unit 1004 is a range where effective pixels exist. The invalid pixel is a pixel that is not output as an image, and is a pixel that is not actually used for generating a radiation image. Outside the effective pixel range in the imaging unit 1004 is a range where no effective pixel exists.

  The reason why there are invalid pixels is that it is difficult to form uniform pixels on a semiconductor wafer, and pixels having different characteristics may be formed at the edge of the semiconductor wafer. Therefore, since the product manufacturer sets effective pixels with a certain margin, in this embodiment, the invalid pixel outside the effective pixel range is used to determine the radiation irradiation range, the presence / absence of the subject 1003, and imaging. Determination of the influence of scattered radiation by the structure of the part 1004 is performed.

  In step S403, image analysis is performed. Since it is difficult to determine a single pixel particularly in a still image, image analysis is performed by performing statistical processing in a range divided into a plurality of pixel areas using a plurality of pixels.

  In step S404, image analysis is started from the coordinates (X = 0, Y = 0) of the pixel plane. Here, X = 0 and Y = 0 are set because the plurality of pixel areas are represented by a coordinate system of two axes of the X-axis and the Y-axis of the pixel plane, so that the coordinates (X = 0, Y = 0) ) To the coordinates of other plural pixel areas, the calculation of all areas is completed.

  In step S405, the arrival dose in the plurality of pixel areas is calculated. The arrival dose can be obtained by, for example, an average value of output values of pixels in a plurality of pixel regions. Further, the arrival dose may be calculated using the time average of the output values of the pixels. When the pixel output value is log output (logarithmic output) with respect to the dose, dose exposure conversion is performed to convert the pixel output value to the dose output value.

  In step S406, a dose L (x, y) and a threshold value T (x, y) at coordinates (X = x, Y = y) are obtained. The dose conversion value for each of the plurality of pixel regions is the dose L (x, y). The threshold value T (x, y), which is a criterion for determining whether or not each of the plurality of pixel regions has been irradiated with radiation, is determined by the irradiation range determining unit 1018 that is a threshold setting unit based on imaging conditions such as the radiation dose. Desired. When the radiation is irradiated, the output value of the pixel generally increases. When the radiation is not irradiated, the threshold value T (x, y) is set by utilizing the fact that the output value of the pixel becomes almost zero. .

  In order to obtain the threshold value T (x, y), it is desirable to use subject information of the subject 1003. That is, when the subject 1003 is very heavy or thick, the radiation is attenuated, and the radiation dose to the imaging unit 1004 decreases.

  In the present embodiment, whether or not radiation is emitted outside the effective pixel range of the imaging unit 1004 and whether or not the radiation applied outside the effective pixel range of the imaging unit 1004 is scattered and affects the image. To be judged.

  By subject recognition processing using a camera, pre-exposure, or the like, the position, range, thickness, length, weight, imaging region, etc. (subject information) of the subject 1003 are recognized. The notification unit 1019 may notify subject information. The irradiation range determination unit 1018 adjusts the threshold value T (x, y) in a plurality of pixel regions where radiation is attenuated by the subject 1003 according to the subject information.

  In particular, when it is recognized from the subject information that the amount of radiation reaching the imaging unit 1004 is decreasing due to the attenuation of radiation at the subject 1003, the threshold value T (x, y) should be reduced. Is desirable. As a result, even if the radiation is attenuated by the subject 1003 outside the effective pixel range, it can be detected that the radiation is emitted.

  For example, when the pixel 1008 covered with the subject 1003 is irradiated with radiation, the radiation attenuates at the subject 1003. Therefore, if the threshold value T (x, y) is not adjusted, the dose L (x, y) is the threshold value. T (x, y) may not be exceeded. In this case, it is determined that radiation has not been applied to the pixel 1008 outside the effective pixel range.

  The radiation attenuated by the subject 1003 is unlikely to affect the image as scattered radiation. However, even if the radiation is attenuated in the pixel 1008, the scattered radiation affects the image when the radiation is irradiated beyond the pixel 1008 to the range where the subject 1003 does not exist.

  Therefore, by reducing the threshold value T (x, y) of the image area covered with the subject 1003, the accuracy of determining the presence or absence of radiation irradiation is improved. The irradiation range determination unit 1018 makes the threshold T (x, y) smaller when the subject 1003 exists at the position of the second pixel sensor 1008 irradiated with radiation than when the subject 1003 does not exist.

  Thereby, it is possible to prevent radiation irradiated outside the pixel region (a region where the pixels 1008 and 1009 do not exist) from affecting the image as scattered rays without being attenuated. Further, since the radiation irradiated outside the effective pixel range (including outside the pixel region) is unnecessary radiation that is not used for the image, unnecessary exposure of the subject 1003 can be avoided.

  In step S407, it is determined whether the calculation of the dose L (x, y) and the threshold value T (x, y) of the pixel region is completed in the X-axis direction. For example, when the calculation for all the plurality of pixel areas on the X axis is finished at Y = 0, the calculation for the plurality of pixel areas in one horizontal row is finished. If the calculation is not completed in the X-axis direction, the process proceeds to step S408, and X is incremented (X = x + 1). And the process of step S405 and step S406 is performed about the several pixel area | region adjacent to an X-axis direction.

  If the calculation is completed in the X-axis direction, the process proceeds to step S409. In step S409, it is determined whether the calculation of the dose L (x, y) and the threshold value T (x, y) of the pixel region is completed in the Y-axis direction.

  If the calculation is not completed in the Y-axis direction, the process proceeds to step S410, and Y is incremented (Y = y + 1). Then, the processes of step S405 and step S406 are performed for the plurality of pixel regions in the X-axis direction at Y = y + 1. When the calculation of the dose L (x, y) and the threshold value T (x, y) for all the pixel areas in the X direction and the Y direction is completed, the calculation for all the areas ends, and the process proceeds to step S411.

  In step S411, the threshold value T (x, y) is corrected using the peripheral region. In step S406, the threshold value T (x, y) is adjusted based on subject information such as the imaging region of the subject 1003. In step S411, the correction using the outer edge pixels is performed by changing the threshold value T (x, y) due to the drop of the profile.

  In step S411, two corrections are performed. The first correction is correction in an area determined as non-irradiation. When the object 1003 includes a substance that absorbs radiation, such as metal, it may be determined that the pixel area corresponding to the absorbing substance is not irradiated with radiation.

  In general, since the outer edge of the irradiation field is limited by an irradiation field stop mechanism (collimator) provided in the radiation irradiation unit 1001, it is rare that the effective pixel range in the irradiation field is not irradiated with radiation. Therefore, when the irradiation range determination unit 1018 recognizes radiation irradiation to the outer edge pixels of the effective pixel range and determines that the effective pixel range inside the outer edge pixels is not irradiated, a portion where the radiation is not irradiated (Non-irradiation part) is specified.

  Then, the irradiation range determination unit 1018 adjusts the threshold value T (x, y) of the pixel corresponding to the non-irradiation unit using the outer edge pixel. In the present embodiment, the outer edge pixel is a pixel at a predetermined distance or range from the outer edge of the effective pixel range or a part thereof. The outer edge pixel may be a pixel at a predetermined distance or range from the outer edge of the radiation irradiation field (imaging region) or a part thereof. In addition, when radiation is emitted outside the effective pixel range, invalid pixels may be included in the outer edge pixels.

  For example, when it is determined that more than half of the predetermined outer edge pixels are irradiated with radiation, the threshold value T (x, y) of the pixel corresponding to the non-irradiated part is reduced, and the determination accuracy of the presence or absence of radiation irradiation To improve. As described above, the irradiation range determination unit 1018 includes a region (non-irradiation unit) in which the radiation dose does not exceed the threshold value at least one inside the outer edge of the first pixel sensor 1009 and the outer edge of the radiographic image capturing region. The threshold value T (x, y) of the non-irradiated part is specified and adjusted.

  The second correction is correction according to the structure of the imaging unit 1004. Even if radiation is emitted outside the effective pixel range and scattered radiation is generated, if the structure of the imaging unit 1004 is uniform, the structure is reflected in the image by the scattered radiation, and the possibility of occurrence of structural unevenness is low. The irradiation range determination unit 1018 adjusts the threshold value T (x, y) for each pixel or for each of a plurality of pixel regions according to the structure of the imaging unit 1004.

  For example, by reducing the threshold value T (x, y) of the pixel 1008 located at a predetermined distance from the structure of the imaging unit 1004 that affects the image, the accuracy of determining the presence or absence of radiation irradiation is improved. The irradiation range determination unit 1018 decreases the threshold value T (x, y) as the distance between the second image sensor 1008 and a predetermined structure (such as an electric board or battery) of the imaging unit 1004 increases. Thereby, it is possible to prevent the radiation irradiated to the pixel 1008 outside the pixel region at a distance close to the structure of the imaging unit 1004 that affects the image from affecting the image as scattered radiation without being attenuated.

  In addition to this embodiment, the irradiation range determination unit 1018 includes the intensity or direction of radiation before passing through the second pixel sensor 1008, the intensity or direction of radiation after passing through the second pixel sensor 1008, and The threshold value T (x, y) may be adjusted according to at least one of the presence / absence of the subject 1003 in the second pixel sensor 1008 and subject information of the subject 1003.

  The irradiation range determination unit 1018 also determines the intensity or direction of the scattered radiation of the radiation that has passed through the second pixel sensor 1008, the distance or direction of the second image sensor 1008 from a predetermined structure, and the scattered position of the scattered radiation. The threshold value T (x, y) may be adjusted according to the distance or direction of the imaging unit 1004 from the predetermined structure and at least one of the predetermined structure of the imaging unit 1004.

  Further, the irradiation range determination unit 1018 may adjust the threshold value by pre-irradiation for irradiating radiation before capturing a radiation image or by irradiation with radiation during capturing of a radiation image.

  In step S <b> 412, it is determined whether or not radiation is applied to the plurality of pixel regions (x, y). The irradiation range determination unit 1018 determines whether or not radiation is irradiated outside the effective pixel range or the imaging region, and specifies the position.

  Until step S411, the dose L (x, y) and threshold value T (x, y) of each of the plurality of pixel regions are calculated. In step S412, the presence / absence of radiation irradiation is determined based on whether or not the dose L (x, y) exceeds the threshold value T (x, y). A plurality of threshold values Ti (x, y) may be set for each pixel or a plurality of pixel regions, and it may be determined whether or not the dose L (x, y) exceeds the threshold value Ti (x, y).

  The irradiation range determination unit 1018 sets a plurality of threshold values Ti (x, y), and the notification unit 1019 can notify a plurality of warnings according to the plurality of threshold values. For example, the notification unit 1019 can notify a plurality of warnings according to the degree of influence of radiation or scattered radiation according to a plurality of threshold values.

  In step S413, it is determined whether or not the radiation irradiation region (radiation irradiation field) exceeds the effective pixel range. By step S <b> 412, the determination of the presence / absence of radiation irradiation in each of the plurality of pixel regions is completed. In step S413, based on the result calculated in the pixel area outside the effective pixel range, it is determined whether or not the radiation irradiation region (radiation irradiation field) exceeds the effective pixel range, and if it exceeds, the position is specified. Is done.

  When the radiation irradiation region (radiation irradiation field) exceeds the effective pixel range, the notification unit 1019 notifies a warning. Based on the determination whether the subject exists in the irradiation field outside the effective pixel range or whether the internal structure of the photographing unit 1004 is reflected in the image, each determination result, the influence of the scattered radiation, or the irradiation field You may display the necessity degree of adjusting.

  In step S414, a radiation image is output. The output radiographic image is output as a diagnostic image by the image processing unit 1013. If the radiation field exceeds the effective pixel range in step S413, the notification unit 1019 gives a warning and uses it for the next imaging.

  FIG. 4 is a diagram illustrating an example of the effective pixel range 1009 and the radiation irradiation region 2000 in the imaging unit 1004 according to the present embodiment. The relationship between the effective pixel range 1009 of the imaging unit 1004 and the radiation irradiation region 2000 will be described with reference to FIG.

  4A and 4B show a case where the radiation irradiation region 2000 exceeds the effective pixel range 1009. FIG. In the case of FIGS. 4A and 4B, as will be described later, the radiation is scattered on the wall behind the imaging unit 1004 and enters the effective pixel range from the rear of the imaging unit 1004. As a result, the electric board 1010 and the battery may be reflected in the image.

  The radiation irradiation region 2000 in FIG. 4B is outside the effective pixel range, but does not exceed the imaging unit 1004. Therefore, there is a high possibility that radiation is shielded by the phosphor and the radiation shielding member in the imaging unit 1004. On the other hand, since the radiation irradiation region 200 in FIG. 4A exceeds the imaging unit 1004, the radiation is not shielded and scattered rays are generated behind the imaging unit 1004. When the scattered radiation enters from behind the imaging unit 1004 and the radiation transmitted through the electrical substrate 1010 exceeds a certain amount, the electrical substrate 1010 appears in the radiation image.

  Here, the electric board 1010 is an example, and includes a battery, a wireless module, a rib for reinforcing the mechanical strength, and the like.

  The radiation irradiation region 2000 in FIG. 4C is within the effective pixel range. In the case of FIG. 4C, the subject 1003 is not irradiated with radiation to pixels that are not actually used for generating the radiation image, and the radiation is widely irradiated beyond the imaging unit 1004. There is nothing.

  FIG. 5 illustrates an example in which radiation that has passed through the pixel 1008 outside the effective pixel range of the imaging unit 1004, the pixel 1009 within the effective pixel range, and the subject 1003 is imaged. Generally, when a radiation irradiation range is set using an irradiation field stop mechanism called a collimator, the radiation irradiation range tends to be widened. However, the imaging area that is really necessary is often a part of the imaging area, and it may be possible to further narrow the radiation irradiation range.

  Also, from the characteristics of the portable FPD, radiation irradiated outside the effective pixel range is not used for imaging, and thus unnecessary radiation is irradiated. The notification unit 1019 can not only notify that radiation has been emitted outside the effective pixel range, but can also perform appropriate notification according to the position of the subject 1003 and the structure of the imaging unit 1004.

  With reference to FIG. 5, the calculation of radiation irradiation will be described using the pixel plane using the pixel values of the invalid pixel, the effective pixel, and the outer edge pixel shown in step S205 of FIG. The pixels of the imaging unit 1004 are divided into effective pixels 301, outer edge pixels 302 in the effective pixel range, and invalid pixels 303. In FIG. 5, the outer edge pixel 302 is a pixel having a predetermined distance or range from the outer edge of the effective pixel range 301 or a part thereof.

  The reason for the presence of invalid pixels is that, in general, the characteristics of the end portion of a large-scale planar semiconductor are different from the central portion, or the characteristics change when dicing. Since the radiation is sharply focused by the irradiation field stop mechanism (collimator) provided in the radiation irradiation unit 1001, if it is determined that the invalid pixel 303 is irradiated with radiation, the radiation is irradiated outside the effective pixel range. Can be determined.

  6 to 9 are diagrams illustrating examples of notification according to the present embodiment. The notification by the notification unit 1019 will be described with reference to FIGS. 6 and 7 are cases where there is a possibility that radiation is emitted outside the effective pixel range.

  In FIGS. 6 and 7, radiation is irradiated on the right side of the radiation image beyond the effective pixel range. A case is assumed in which it is determined that the electric board 1010 exists at a predetermined distance from a position corresponding to the right side of the radiographic image. In this case, the notification unit 1019 notifies a message that there is a possibility that radiation is emitted outside the effective pixel range. Further, the notification unit 1019 reflects the number of sides outside the effective pixel range irradiated with radiation, its position (in the right side of the radiographic image in FIG. 6), the presence or absence of a subject at that position, and the structure of the imaging unit 1004. Notify the possibility of occurrence.

  In FIGS. 8 and 9, no radiation is irradiated outside the effective pixel range. In this case, the notification unit 1019 notifies a message that radiation is being irradiated within the effective pixel range. In addition, the notification unit 1019 includes the number of sides outside the effective pixel range irradiated with radiation, its position (not applicable in FIG. 8), the presence or absence of a subject at that position (not applicable in FIG. 8), and the imaging unit 1004. The presence / absence of the possibility of the reflection of the structure (not applicable in FIG. 8) is notified.

  FIG. 10 is a diagram for explaining that scattered rays appear in an image. The imaging unit 603 includes a sensor 604, a shielding material 605, an electric board / battery 606, and the like. The radiation 601 passes through the subject 1003 and is photoelectrically converted by the sensor 604, and a radiation image is generated based on the output value of each pixel. The sensor 604 includes a method of converting radiation into an electric signal by photoelectric conversion, and a method of converting the light into light having a wavelength such as visible light by a phosphor and then converting the light into an electric signal by photoelectric conversion.

  In FIG. 10, the case where the radiation 602 is irradiated in a wider range than the imaging unit 603 is considered. Since the irradiated radiation 602 does not reach the sensor 604, it is not used for imaging, but is scattered and absorbed at the wall 607 and the like. The radiation 602 that is not attenuated by the imaging unit 603 becomes scattered radiation at the wall 607 and may enter the imaging unit 603 from behind.

  The imaging unit 603 may be provided with a shielding material 605 having a function of preventing scattered rays from the rear. However, when the heavy shielding material 605 is thinned due to the demand for reducing the weight of the cassette type FPD, the function of shielding the radiation from the rear is weakened. In such a case, the electric board / battery 606 of the imaging unit 603 may be reflected in the radiographic image.

(Second Embodiment)

  The second embodiment for carrying out the present invention will be described below in detail with reference to the drawings. FIG. 11 is a diagram showing a configuration of the radiation imaging apparatus 2001 according to the first embodiment of the present invention. Note that the description of the same configuration, function, and operation as in the above embodiment is omitted, and differences from the present embodiment are mainly described.

  Unlike the first embodiment, an irradiation field recognition unit 1011 by image processing is provided. The irradiation field recognition unit 1011 recognizes the outer edge of the radiographic image capturing area.

  In general, since the outer edge of the irradiation field is limited by an irradiation field stop mechanism (collimator) provided in the radiation irradiation unit 1001, it is rare that the radiation is not irradiated to the effective pixel range inside the outer edge of the irradiation field. Therefore, when the irradiation field recognition unit 1011 recognizes the outer edge of the irradiation field (imaging region) and determines that the effective pixel range in the irradiation field is not irradiated with radiation, a portion not irradiated with radiation (non-irradiation unit) ).

  In this case, the outer edge pixel is a pixel at a predetermined distance or range from the outer edge of the irradiation field (imaging region) or a part thereof. When the outer edge of the radiation field is limited, or when a metal or the like is arranged in the subject 1003, the radiation irradiation range can be accurately grasped more accurately than in the first embodiment.

  The irradiation range determination unit 1018 adjusts the threshold value T (x, y) of the pixel corresponding to the non-irradiation unit. When radiation is emitted outside the effective pixel range, invalid pixels may be included in the outer edge pixels. In this case, the irradiation field recognition unit 1011 determines not only the pixel 1009 within the effective pixel range but also the pixel 1008 outside the effective pixel range, and the range irradiated with radiation outside the effective pixel range.

  Radiation is sharply shielded by the collimator. In this case, due to the difference between the range set by the collimator and the actual radiation field, even if the radiation field is set to the effective pixel range, the actual radiation field becomes wider or narrower than the effective pixel range. This is because there is a possibility.

  FIG. 12 is a flowchart illustrating processing according to the present embodiment. In step S805, the irradiation field recognizing unit 1011 recognizes the outer edge of the irradiation field (imaging region), and the irradiation range determining unit 1018 is a pixel at a predetermined distance or range from the outer edge of the imaging region or a part thereof (outer edge pixel). The pixel value is used for calculation. For example, when it is determined that more than half of the predetermined outer edge pixels are irradiated with radiation, the threshold value T (x, y) of the pixel corresponding to the non-irradiated part is reduced, and the determination accuracy of the presence or absence of radiation irradiation To improve.

  Since an image is output immediately after the FPD apparatus is used, a technique for recognizing a radiation irradiation field using image processing has been developed. Therefore, the radiation field recognition unit 1011 recognizes the radiation field not only after the radiation imaging but also during the radiation imaging by reading pre-exposure before actual radiation imaging or reading out the pixel output signal during radiation irradiation. It may be broken.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is not limited to these, It can change and change within the range described in the claim.

  There are a wide variety of radiographic systems that can be installed with the radiographic apparatus according to the present invention. In general, the irradiation field stop mechanism (collimator) of the radiation irradiation unit 1001 is often rectangular. In this case, since the irradiation field has a rectangular shape and may be different from the shape of the subject 1003, unnecessary exposure of the subject 1003 can be avoided by applying the function of the present invention, and the scattered radiation affects the image. Giving can be prevented.

  Further, the pixel 1008 outside the effective pixel range may be a pixel for performing automatic exposure control. The pixel 1008 outside the effective pixel range is configured to perform automatic exposure control (Automatic Exposure Control (AEC)) that terminates radiation irradiation when the radiation dose reaches a target value.

  By reading the output signal of the pixel 1008 outside the effective pixel range while driving the pixel 1008 outside the effective pixel range, the output signal of the pixel 1008 outside the effective pixel range is monitored. A control signal for ending radiation irradiation in response to the calculation value obtained by the cumulative addition reaching the target value by cumulatively adding the output signals of the pixels 1008 outside the effective pixel range monitored. Is output to the radiation generator. The radiation generator ends the radiation irradiation. Therefore, since radiation irradiation can be stopped when the pixel 1008 outside the effective pixel range is irradiated with radiation, unnecessary radiation exposure can be suppressed.

  The present invention supplies software (programs) for realizing the functions of the above-described embodiments to a system or apparatus via a network or various storage media, and a computer (CPU, MPU, etc.) of the system or apparatus reads the program. May be executed. The present invention can also be realized by a process in which one or more processors in a computer of a system or apparatus read and execute a program, and can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

1000, 2001 Radiation imaging apparatus 1001 Radiation irradiation unit 1002 Radiation 1003 Subject 1004 Imaging unit 1005 Control unit 1006 Data collection unit 1007 Preprocessing unit 1008 Invalid pixel range (second pixel sensor)
1009 Effective pixel range (first pixel sensor)
1010 Electric board 1011 Irradiation field recognition unit 1013 Image processing unit 1014 CPU
1015 Memory 1016 Operation panel 1017 Image display 1018 Irradiation range determination unit 1019 Notification unit 1022 Subject determination unit 1023 Structure determination unit 2000 Radiation irradiation region

Claims (20)

An imaging means including a plurality of pixel sensors for detecting radiation;
Irradiation detection means for detecting radiation irradiated to a second pixel sensor other than the first pixel sensor used for generating a radiation image among the plurality of pixel sensors;
A radiation imaging apparatus comprising: notification means for notifying that the radiation has been applied to the second pixel sensor. The first pixel sensor is used to generate a radiation image,
The radiation imaging apparatus according to claim 1, wherein the second pixel sensor is not used to generate a radiation image.   The radiation imaging apparatus according to claim 1, wherein the second pixel sensor includes a pixel sensor for performing automatic exposure control.   The pixel sensor for performing the automatic exposure control cumulatively adds the output signals of the image sensor, and terminates the radiation irradiation in response to a calculation value obtained by the cumulative addition reaching a target value. The radiographic apparatus according to claim 3, wherein a control signal for output is output to the radiation irradiation unit.   The radiation detection means detects that radiation has been irradiated outside the range of effective pixels used for generating a radiation image among the plurality of pixel sensors. The radiation imaging apparatus of Claim 1.   The irradiation detection means sets a predetermined threshold based on the radiographic image capturing condition, and detects the radiation when the amount of radiation irradiated to the pixel sensor exceeds the threshold. The radiation imaging apparatus according to any one of claims 1 to 5.   The irradiation detection means includes the intensity or direction of radiation before passing through the second pixel sensor, the intensity or direction of radiation after passing through the second pixel sensor, and the presence or absence of a subject in the second pixel sensor. , Subject information of the subject, intensity or direction of scattered radiation of radiation transmitted through the second pixel sensor, distance or direction between the second image sensor and a predetermined structure of the imaging means, scattering of the scattered radiation The radiographic apparatus according to claim 6, wherein the threshold is adjusted according to a distance or direction between a position and a predetermined structure of the imaging unit and at least one of the predetermined structure of the imaging unit. .   The said irradiation detection means makes the said threshold value smaller when the subject exists at the position of the second pixel sensor irradiated with the radiation than when the subject does not exist. Radiography equipment.   9. The radiation imaging apparatus according to claim 1, further comprising subject determination means for determining presence or absence of a subject at a position of the second pixel sensor irradiated with the radiation.   The radiation imaging apparatus according to claim 6, wherein the irradiation detection unit decreases the threshold as the distance between the second image sensor and the predetermined structure of the imaging unit increases.   The intensity or direction of the scattered radiation of the radiation that has passed through the second pixel sensor, the distance or direction between the second image sensor and the predetermined structure of the imaging means, the scattering position of the scattered radiation, and the predetermined of the imaging means A structure judging means for judging the degree to which the predetermined structure of the imaging means is reflected in the radiation image by the scattered radiation according to at least one of the distance or direction to the structure and the predetermined structure of the imaging means. The radiation imaging apparatus according to any one of claims 1 to 10, further comprising: The irradiation detection means includes the intensity or direction of radiation before passing through the second pixel sensor, the intensity or direction of radiation after passing through the second pixel sensor, and the presence or absence of a subject in the second pixel sensor. , Subject information of the subject, intensity or direction of scattered radiation of radiation transmitted through the second pixel sensor, distance or direction between the second image sensor and a predetermined structure of the imaging means, scattering of the scattered radiation A plurality of threshold values are set according to the distance or direction between the position and the predetermined structure of the photographing unit and at least one of the predetermined structure of the photographing unit,
The radiation imaging apparatus according to claim 6, wherein the notification unit can notify a plurality of warnings according to the plurality of threshold values.   The radiation imaging apparatus according to claim 1, wherein the notification unit performs the notification so as to limit the radiation applied to the second pixel sensor. An imaging means including a plurality of pixel sensors for detecting radiation;
An irradiation detection unit configured to set a predetermined threshold based on radiographic imaging conditions, and detect radiation irradiated to the plurality of pixel sensors when the amount of radiation irradiated to the pixel sensor exceeds the threshold; ,
A radiation imaging apparatus comprising: notification means for notifying that the pixel sensor is irradiated with the radiation.   The irradiation detection means specifies an area where the radiation dose does not exceed the threshold value at least one inside the outer edge of the range of the first pixel sensor and the outer edge of the radiographic image capturing area, and The radiation imaging apparatus according to claim 14, wherein a threshold value is adjusted.   A radiation imaging apparatus comprising irradiation field recognition means for recognizing an outer edge of an imaging region of the radiation image.   The said irradiation detection means sets or adjusts the said threshold value by the pre-irradiation which irradiates the said radiation before imaging | photography of the said radiographic image, or the irradiation of the said radiation during imaging | photography of the said radiographic image. 14. The radiographic apparatus according to 14. Radiation irradiating means for irradiating radiation;
An imaging means including a plurality of pixel sensors for detecting the radiation;
Irradiation detection means for detecting radiation irradiated to a second pixel sensor other than the first pixel sensor used for generating a radiation image among the plurality of pixel sensors;
A radiation imaging system comprising: notification means for notifying that the radiation has been applied to the second pixel sensor. A step of detecting radiation irradiated to a second pixel sensor other than the first pixel sensor used for generating a radiation image among a plurality of pixel sensors for detecting radiation;
And a step of notifying that the radiation has been applied to the second pixel sensor.   The program for functioning a computer as each means of the radiography apparatus of any one of Claims 1 thru | or 17.