JP4737724B2 - Radiation image processing device - Google Patents

Description

  The present invention relates to a radiographic image processing apparatus used in the medical field using radiation.

  2. Description of the Related Art Conventionally, a radiographic imaging apparatus capable of obtaining a digital radiographic image for diagnosing a disease or the like is known, and a part of the radiation energy is accumulated and irradiated with excitation light according to the accumulated energy. Generates an electrical signal corresponding to the dose of radiation irradiated by a device using a stimulable phosphor exhibiting stimulated emission or a plurality of two-dimensionally arranged detection elements, and based on this electrical signal, generates an image Devices such as Flat Panel Detector (FPD) that generate data are used.

  On the other hand, the radiographic image is an image of a shadow due to the fact that when the radiation passes through the subject, the amount of transmitted radiation varies depending on the atomic amount of the substance constituting the subject. That is, a two-dimensional distribution of the radiation amount emitted from the radiation source and transmitted through the subject is detected by the radiation image detector, and a radiation image based on the radiation absorption contrast of the subject is formed.

  By the way, since the radiation is an electromagnetic wave, it has a wave property. Therefore, when it passes through the subject, diffraction or refraction due to a phase shift occurs, and this can be detected as an image.

  In recent years, a method for capturing a radiographic image with high subject contrast using this property has been proposed, and is called a phase contrast radiographic image or a refractive contrast radiographic image. In this image, since the contrast of the boundary portion of the subject is particularly enhanced, the radiographic image detectability is improved. Therefore, application to the medical field using radiation, the industrial nondestructive inspection field, and the like is expected.

  By the way, in the same manner as a normal radiographic image, a PCI radiographic image can be obtained directly as a digital image as described above, or digitized by an analog image and a scanner, etc. to obtain a digital PCI radiographic image. Can do. Since the PCI radiographic image of such a digital image is different from the normal captured image so far, an optimal image processing method different from the image captured by the normal capture is necessary. There is also the possibility of a new energy subtraction method using PCI radiographic images. In addition, since the PCI radiographic image is an enlarged image, it is necessary to output it at a size that is easy to diagnose. Furthermore, there is a possibility that the accuracy of diagnosis support can be improved by using PCI radiographic images.

  The present invention has been made in view of such circumstances, and aims to provide a radiographic image processing apparatus capable of performing appropriate image processing of radiographic images, and radiographic image processing capable of improving the image quality of energy subtraction. The object is to provide a device.

  In order to solve the above-described problems and achieve the object, the present invention is configured as follows.

The radiation image processing apparatus of the invention includes a X-ray tube focus size D ([mu] m) is 30 to 1,000, and X-ray detector for detecting X-ray image transmitted through the Utsushitai,
The distance R 1 (m) from the X-ray tube before Symbol the Utsushitai, R 1 ≧ (D (μm ) - 7) in a range of / 200, the distance from the object to the X-ray detector R2 the (m), means for imaging as well as imaging the first radiographic image and the R2 ≧ 0.15, the second radiation image is brought into close contact with the object to the X-ray detector,
Processing means for performing a first radiographic image, the size adjustment before Symbol second radiation image,
And a means for creating a difference image between the first radiographic image and the second radiographic image subjected to size matching.

A first X-ray detector for imaging the pre-Symbol first radiographic image, and a second X-ray detector for imaging the second radiation image, the first X-ray detector and the second that having a filter containing a low energy component absorbing material of the radiation between the X-ray detector.

In addition, it has shooting information storage means for storing management information relating to shooting, including an enlargement ratio,
Before Kisho management means, on the basis of the enlargement rate included in the management information on imaging combined magnitude of the second radiation image with the first radiographic image, it is possible to perform subsequent positioning process. The front Kisho management means, the determined enlargement ratio based on the analysis result of the first radiation image and the second radiographic image, the said based on the enlargement ratio obtained first radiation image first The size of the two radiographic images can be adjusted, and then the alignment process can be performed.

  The radiographic image processing apparatus according to the present invention detects a first radiographic image captured by an X-ray imaging apparatus and enhanced by image edge enhancement by refraction contrast enhancement and sharpness that is reduced by a penumbra and X-ray detection of a subject. A difference image with the second radiographic image photographed in close contact with the vessel is created, and appropriate image processing of the radiographic image is possible, and the image quality of energy subtraction can be improved.

  Hereinafter, embodiments of the radiation image processing apparatus of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments.

  In the radiographic image processing apparatus of the present invention, and in the PCI radiographic image detection processing apparatus, the PCI radiographic image output apparatus, and the PCI diagnostic imaging support apparatus, a PCI radiographic image that is digital data is used, and the PCI radiographic image is directly converted into a digital image. There are cases where the image is obtained, and cases where the image obtained as an analog image is digitized.

  This PCI radiation image is obtained by photographing with the apparatus of Japanese Patent Application No. 11-203969, the apparatus of Japanese Patent Application No. 11-266605, the apparatus of Japanese Patent Application No. 2000-44381, the apparatus of Japanese Patent Application No. 2000-53562, or the like. This is an image obtained by a photographing method such as the method of Japanese Patent Application No. 11-203969, the method of Japanese Patent Application No. 11-266605, the method of Japanese Patent Application No. 2000-44381.

  The apparatus described in Japanese Patent Application No. 11-203969 includes an X-ray tube having a focal size (D μm) of 30 μm or more, a fixing means for fixing a subject position, and an X-ray detection for detecting an X-ray image transmitted through the subject. The fixing means includes a distance R1 (m) from the X-ray tube to the subject fixed by the fixing means within a range of an expression of R1 ≧ (D-7) / 200 (m), and fixing means. The X-ray imaging apparatus is configured such that the distance R2 from the fixed subject to the X-ray detector can be set to 0.15 m or more.

In addition, the method described in Japanese Patent Application No. 11-203969 uses an X-ray detector to detect an X-ray image irradiated from an X-ray tube and transmitted through a subject, and reduces sharpness that is deteriorated by a penumbra. Is an X-ray image capturing method enhanced by image edge enhancement by the above, and an X-ray image capturing method using an X-ray tube having a focal size (D μm) of 30 μm or more, and a distance R1 from the X-ray tube to the subject (M) R1 ≧ (D-7) / 200 (m)
And the distance R2 from the subject to the X-ray detector is 0.15 m or more.

  In the apparatus and method described in Japanese Patent Application No. 11-203969, the distance R1 is 10> R1 ≧ (D-7) / 200 (m), and 0.7 ≦ R1 ≦ 5 (m). The focus size of the X-ray tube is not less than 30 μm and not more than 1000 μm, the focus size of the X-ray tube is not less than 50 μm and not more than 500 μm, and the energy of the emission line spectrum of the X-ray irradiated to the subject is It is more preferable that it is 10 keV or more and 60 keV or less, the anode of the X-ray tube has molybdenum or rhodium, the pixel size of the X-ray detector is 1 μm or more and 200 μm or less, and the like.

  Japanese Patent Application No. 2000-44381 discloses an X-ray tube that emits diverging X-rays, a subject holder for fixing the subject to the X-ray tube, and an X-ray image that passes through the subject. X-rays emitted from an X-ray tube when a blur width due to a penumbra of the X-ray image is B (μm) and an edge enhancement width due to X-ray diffraction contrast is E (μm) Is an X-ray imaging apparatus in which a subject holder and an X-ray image detector can be installed so that 9E ≧ B when X-ray magnified imaging is performed through a subject.

  The method described in Japanese Patent Application No. 2000-44381 uses an X-ray tube that emits divergent X-rays, transmits X-rays radiated from the X-ray tube to the subject, and performs X-ray enlargement imaging. X-ray image shooting in which 9E ≧ B is satisfied, where B (μm) is the blur width due to the penumbra of the X-ray image obtained by X-ray enlargement imaging, and E (μm) is the edge enhancement width due to X-ray refraction contrast. Is the method.

  Regarding the apparatus and method described in Japanese Patent Application No. 2000-44381, the distance R1 between the X-ray tube and the subject is separated by 0.5 m or more, the distance R2 between the subject and the X-ray image detector is separated by 1 m or more, Furthermore, the R1 + R2 is 5 m or less, the X-ray magnified imaging is 1.0 to 10 times, the focal size of the X-ray tube is 10 μm or more and 1000 μm or less, and the focal size of the X-ray tube Is 30 μm or more and 300 μm or less, the set tube voltage of X-rays irradiated to the subject is 50 to 150 kVp, the X-ray tube is a tungsten rotating anode X-ray tube, and the pixel of the X-ray detector It is a more preferable embodiment that the size is 1 μm or more and 200 μm or less.

  The edge emphasis width E can be expressed by the following three expressions, for example. Here, R1: X-ray source-subject distance (m), R2: Subject-X-ray image detector (m), λ: wavelength of maximum X-ray dose (Å), A: When subject is a cylinder The diameter (mm) of the circle of the cross section, δ: difference in refractive index between the object and air.

E = 39 × R2 (1 + 0.045 / R1) × λ ² × √A E = 27 × (1 + R2 / R1) ^1/3 × (λ ² × R2 × √A) ^2/3 E = 2.3 × ( 1 + R2 / R1) ^1/3 × (R2 × δ × √A) The device described in ^{2/3 Japanese} Patent Application No. 11-266605 is movable on a support member and can be fixed temporarily. An apparatus and a film cassette holder; the distance between the cooling X-ray tube and the film cassette holder screen and film system can be separated by 70 cm or more; It is an X-ray image capturing apparatus that can capture an X-ray refraction contrast image and can be separated from the film system by a distance of 20 cm or more.

  In addition, the method described in Japanese Patent Application No. 11-266605 includes a subject support device and a film cassette holder that are movable on a support member and can be temporarily fixed, and hold a cooling X-ray tube and a film cassette. X-ray imaging that captures X-ray refraction contrast images with a distance of 70 cm or more between the screen and film system of the tool, and a distance of 20 cm or more between the subject of the object support device and the screen and film system of the film cassette holder Is the method.

  The device of Japanese Patent Application No. 2000-53562 includes a small-focus radiation source that irradiates a subject with radiation, a holding member that holds the subject, a reading unit that reads radiation image information based on radiation transmitted through the subject, and a small-focus radiation source. A distance changing means for changing a first distance between the holding member and the second distance between the holding member and the reading means, and a control means for controlling the radiation conditions of the small focus radiation source, The control means is a radiographic image capturing apparatus that controls the radiation conditions of the small focus radiation source according to at least distance information regarding the first distance or the second distance, and the small focus radiation source that irradiates the subject with radiation, and the subject Holding member, reading means for reading radiation image information based on radiation transmitted through the subject, image display means or radiation image for displaying radiation image information A radiographic imaging apparatus having an image output means for outputting information, and having a control means for changing from an image enlargement ratio at the time of radiographic imaging and displaying radiographic image information by an image display means or outputting by an image output means is there.

  Normal shooting refers to shooting with a subject in close contact with a detector and, optionally, through a grid. A normal shooting image is an image obtained by normal shooting.

  In addition, a PCI radiographic imaging apparatus that can directly obtain a PCI radiographic image as a digital image is an apparatus that can capture a PCI radiographic image as well as normal imaging (general imaging that is normally performed).

  In the present invention, the drawings for explaining the embodiments are shown. However, each drawing is an example, and the present invention is not limited to this.

  First, an embodiment of a PCI radiation image processing apparatus and a PCI radiation image detection processing apparatus will be described.

  FIG. 1 is a diagram illustrating a configuration of a PCI radiographic image processing apparatus and a PCI radiographic image detection processing apparatus. The PCI radiographic image processing apparatus and PCI radiographic image detection processing apparatus of this embodiment have a control unit 10. The radiation source 30 is controlled by the control unit 10, but is not limited to the control by the control unit 10. The radiation emitted from the radiation generation source 30 passes through the subject 5 and irradiates the imaging panel 41 mounted on the front surface of the radiation image reader 40 that is the radiation image detection means 200.

  As the radiation source 30, a Mo tube, an Rh tube, a W tube, or the like is used. For PCI imaging, a high-power X-ray source with a small focal diameter of the tube is desirable. As an example of high output, the rotating anode moves little by little while the electron beam is irradiated so that the electron beam irradiated to the rotating anode (target) does not hit the same position on the concentric circle of the rotating anode. The method of doing is conceivable. For taking a PCI radiation image, a radiation source having a radiation tube focal spot diameter of 30 to 500 μm and a maximum tube current of 50 mA or more is preferable.

  Next, a desirable mode for the arrangement of the X-ray tube focus will be described. In imaging of the breast and the arm close to the body, the subject and the detector are in close contact with each other in normal imaging, so that the portion placed on the detector can be imaged regardless of the position of the focal point of the X-ray tube. That is, if it is mammography, the chest wall can be imaged. On the other hand, since the subject and the detector are separated in enlarged photographing such as a PCI radiographic image, a desired portion cannot be photographed unless the X-ray tube focus and the detector position are appropriate for the subject. In other words, it is necessary to optimize the X-ray tube focus or detector arrangement.

  For example, in the mammography apparatus, as shown in FIG. 2A, the X-ray tube focal point 900 is arranged slightly on the column 901 side (the side far from the subject) from vertically above the end of the subject support. In this case, in magnified imaging such as a PCI radiographic image, if the detector 902 tries to capture the radiation information of the chest wall properly, the detector 902 is closer to the subject side from the vertically lower side of the end of the subject support portion, so that it is difficult to photograph. A point arises.

For this reason, as shown in FIG. 2B, it is desirable that the X-ray tube focal point 900 be disposed on the subject 903 side with respect to normal imaging in enlarged imaging such as a PCI radiation image.
The arrangement of the X-ray tube focal point 900 is not limited to digital PCI radiographic imaging, but can also be applied to analog systems such as a screen / film and general enlarged imaging.

In the radiation image reader 40, a detector for directly obtaining a PCI radiation image as digital data is used, and solid-state imaging such as a stimulable phosphor plate (imaging plate) and a flat panel detector: FPD (direct method, indirect method). There are an element, a phosphor (Gd ₂ O ₂ S: Tb, CsI, etc.), a lens (or taper), and a device using a CCD. When these detectors are used, the PCI radiation image is an enlarged image, which corresponds to a reduction in the pixel size of the detector. In other words, this corresponds to high-definition reading and has the advantage of increasing image information.

  When the stimulable phosphor plate is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of the radiation energy is accumulated, and then irradiated with excitation light such as visible light. Then, using a stimulable phosphor (stimulable phosphor) that exhibits stimulating luminescence according to the stored energy, radiation image information of a subject such as a human body is once recorded on the stimulable phosphor on the sheet, The stimulable phosphor sheet is scanned with excitation light such as laser light to generate stimulated emission light, and the obtained stimulated emission light is photoelectrically read to obtain an image signal. A radiation image can be output as a visible image on a recording material such as a photographic material, a CRT, etc. (Japanese Patent Laid-Open Nos. 55-124929, 56-163472, 56-104645, 55-116340, etc.) ).

  As a solid-state imaging device such as a flat panel detector, for example, as described in JP-A-6-342098, a photoconductive layer that generates charges according to the intensity of irradiated X-rays, and generated charges Is stored in a plurality of capacitors arranged two-dimensionally. Further, as described in JP-A-9-90048, a photodiode or the like in which X-rays are absorbed by a phosphor layer such as an intensifying screen to generate fluorescence and the intensity of the fluorescence is provided for each pixel. A method of detecting with a photodetector is also used. As another fluorescence detection means, there is a method using a CCD or a C-MOS sensor. In addition, a configuration in which an X-ray scintillator that emits visible light by X-ray irradiation, a lens array, and an area sensor corresponding to each lens is also used.

  Although different from the configuration of FIG. 1, for example, radiographic images are usually taken using an X-ray film in group examination, and in order to input these X-ray photographs to the system of this embodiment, a laser is used. Use a digitizer. This is obtained as digital image data by scanning a film with a laser beam, measuring the amount of transmitted light, and converting the value into analog to digital. By inputting this image data to the control unit 10, it can be handled as a digital image in the same manner as described above.

  When a digital X-ray image is obtained with the various configurations described above, the effective pixel size of the image is preferably 200 μm or less, particularly 100 mm or less for a mammogram, depending on the imaging region and the diagnostic purpose. It is preferable. Further, the number of gradations of the image is preferably 10 bits or more, and particularly preferably 12 bits or more.

  Enlarged shooting is indispensable in PCI shooting, and accordingly, a detector having a large area is required in some cases. As an application example in such a case, there is a method in which a plurality of imaging plates or screens / films are photographed side by side, the images after photographing are superimposed, and the images are processed. The above-described detector in which a large number of units using phosphors, lenses, and CCDs are arranged is effective in increasing the area. In these cases, it is necessary to interpolate the joint (gap) of the image by an appropriate interpolation process.

  In normal imaging, although depending on the imaging region, a grid is generally used, but in PCI imaging, the scattered radiation can be removed by an air gap, so the grid is not used. For this reason, since there is no radiation absorption by a grid, there is no loss in radiation information.

  An input unit 27 such as a keyboard is connected to the control unit 10 via an input interface 17. By operating the input unit 27, information for identifying image data obtained, information related to photographing, and the like are stored. Management information is entered.

  Further, an output unit 28 is connected to the control unit 10 via the output interface 18. As the output means 28, an image can be obtained by developing with an automatic developing machine using a silver halide photographic light-sensitive material, or a silver halide photographic light-sensitive material, but an image is drawn by heating according to radiation image information. These are also preferred embodiments. Also, a solid ink jet recording method that draws an image by ejecting liquid ink heated from solid ink at room temperature, an ink jet recording method that draws an image by ejecting a dye or pigment that is liquid at room temperature from a nozzle, an ink ribbon Hard copy by a method that draws an image by sublimation by heating and fixing it to a recording medium, an ablation image forming method by evaporating a sheet coated with carbon etc. on one side with laser light etc. based on image information The use is a preferred embodiment.

  As for image output or image display by the output means 28, usually only one processed image is output or displayed. In addition, images before and after processing can be output or displayed in parallel, or if there are images of the same subject, they can be output or displayed side by side.

  Management information indicating identification of the subject 5 to be photographed and information related to photographing is input to the control unit 10 using the input unit 27. Input of management information using the input means 27 is performed by operating a keyboard, using a magnetic card, a bar code, HIS (in-hospital information system: network-based information management), or the like. This management information includes, for example, an ID number, name, date of birth, sex, imaging date and time, imaging site and imaging position (for example, which part of the human body was irradiated with radiation from which direction), imaging method (simple imaging, contrast imaging) Imaging, tomography, magnified imaging, etc.), imaging conditions (tube voltage, tube current, irradiation time, X-ray tube focal point-subject distance: R1, subject-detector distance: R2, magnification factor, use of scattered radiation removal grid Or the like), whether the captured image is a PCI radiographic image or a normal captured image, the sampling pitch of the detector, and information such as the diagnostic purpose. Furthermore, it is not limited to these.

  The control unit 10 includes a CPU 11 and an image processing unit 100, and the shooting date and time can be obtained automatically from the CPU 11 using a clock function built in the CPU 11. It should be noted that the management information to be input may be only related to the subject to be photographed at that time. A series of management information is input in advance, and the subjects are photographed in the order of input, or the management that has been input as necessary. Information may be read and used.

  The control unit 10 includes an image processing unit 100 that performs image processing on a PCI radiation image and a normal captured image, and is a radiation image detection unit 200 that outputs an image signal corresponding to the captured PCI radiation image and the normal captured image. Image processing can be performed on the image signal output from the image reader 40, and image processing corresponding to the PCI radiation image and the normal captured image input from the input unit 27 can be performed.

  The image processing unit 100 includes a PCI image processing unit 110 that performs image processing on a PCI radiation image, and a normal captured image processing unit 120 that performs image processing on a normal captured image. Since the image processing conditions differ depending on whether the image is a PCI radiographic image or a normal image, a PCI image processing unit 110 and a normal image processing unit 120 corresponding to each are provided.

  In addition, the image processing unit 100 includes a shooting information storage unit 300 that stores management information related to shooting. The image processing unit 100 determines image processing conditions using information related to shooting stored in the shooting information storage unit 300, and performs processing based on the image processing condition. Do.

  The management information relating to the shooting may be held in the shooting information storage unit 300, or may be held by the image itself as header information or the like.

  Each of the PCI image processing unit 110 and the normal captured image processing unit 120 includes the image processing circuit 12 shown in FIG. The image processing circuit 12 performs gradation processing to obtain a radiographic image having a density and contrast suitable for diagnosis or the like even if the level distribution of the image data of a PCI radiographic image or a normal captured image fluctuates.

  Although not shown, the image processing circuit 12 performs frequency enhancement processing for controlling the sharpness of the radiographic image with respect to the image data DTreg and the entire radiographic image having a wide dynamic range, and the contrast of the fine structure portion of the subject. It is also possible to perform a dynamic range compression process for keeping the density within an easy-to-view density range without lowering.

  By the way, when taking a radiographic image, for example, in order to prevent radiation from being applied to a part that is not required for diagnosis, or to a part that is not required for diagnosis, radiation scattered in this part is used for diagnosis. In order to prevent the resolution from being reduced by being incident on a required portion, a radiation non-transparent material such as a lead plate is installed in a part of the subject 5 or the radiation generator 30 so that the radiation field to the subject 5 is irradiated. Irradiation field restriction is performed to limit the above.

  When this irradiation field stop is performed, if level conversion processing and subsequent gradation processing are performed using the image data of the irradiation field area and the irradiation field area, the image data in the irradiation field is determined by the image data of the irradiation field area. Image processing of a part required for diagnosis is not performed properly. For this reason, irradiation field recognition for discriminating between the irradiation field inner region and the irradiation field outer region is performed.

  In the irradiation field recognition, for example, a method disclosed in Japanese Patent Laid-Open No. 63-259538 is used, and a line segment from a predetermined position P on the imaging surface toward the end of the imaging surface as shown in FIG. For example, differentiation processing is performed using the above image data. As shown in FIG. 4B, the differential signal Sd obtained by this differentiation processing has a signal level that is high at the irradiation field edge portion. Therefore, one signal field edge candidate point is determined by determining the signal level of the differential signal Sd. EP1 is required. A plurality of irradiation field edge candidate points EP1 to EPk are obtained by performing processing for obtaining the irradiation field edge candidate points radially about a predetermined position on the imaging surface. An irradiation field edge portion is obtained by connecting adjacent edge candidate points of the plurality of irradiation field edge candidate points EP1 to EPk obtained in this way with straight lines or curves.

  Moreover, the method shown by Unexamined-Japanese-Patent No. 5-7579 can also be used. In this method, when the imaging surface is divided into a plurality of small areas, the radiation dose of the radiation is reduced substantially uniformly in the small areas outside the irradiation field where radiation irradiation is blocked by the irradiation field stop. Becomes smaller. In addition, in a small region within the irradiation field, the radiation value is modulated by the subject, so that the dispersion value is higher than that outside the irradiation field. Further, in a small region including the irradiation field edge portion, the portion with the smallest radiation dose and the portion with the radiation dose modulated by the subject coexist, so the dispersion value is the highest. From this, the small area including the irradiation field edge portion is determined by the dispersion value.

  Moreover, the method shown by Unexamined-Japanese-Patent No. 7-181609 can also be used. In this method, image data is rotated about a predetermined center of rotation, and rotation is performed until the boundary line of the irradiation field becomes parallel to the coordinate axis of the orthogonal coordinates set on the image by the parallel state detection means. When the state is detected, the linear equation of the boundary before rotation is calculated by the linear equation calculation means based on the rotation angle and the distance from the rotation center to the boundary line. Thereafter, by determining a region surrounded by a plurality of boundary lines from a linear equation, the region of the irradiation field can be determined. When the irradiation field edge portion is a curve, for example, one boundary point is extracted based on the image data by the boundary point extraction means, and the next boundary point is extracted from the boundary candidate point group around this boundary point. Similarly, by sequentially extracting boundary points from the boundary candidate point group around the boundary points, it is possible to determine whether the irradiation field edge portion is a curve.

  When the irradiation field recognition is performed in this way, the recognized irradiation field region is an area for determining the distribution of the image data level (hereinafter referred to as “the distribution of the image data when converting the distribution of the image data into the distribution of the desired level”). The region of interest ”). By determining a representative value from the image data in the region of interest and converting the representative value to a desired level, image data of a desired level can be obtained.

  This region of interest is not limited to being equal to the irradiation field region. For example, since it is generally performed that the most important part for diagnosis is taken as the center of the irradiation field, a region such as a circle or a rectangle is set at the center of the irradiation field region and the region of interest It is good also as what to do. Here, in a circular or rectangular region, the diameter of the circle or the length of one side of the rectangle is set, for example, as “1/2 to“ 1/5 ”of the long side, short side, or diagonal line of the irradiation field.

  Furthermore, a region of interest corresponding to a predetermined human body structure may be set in the irradiation field region. For example, as shown in Japanese Patent Laid-Open No. 3-218578, the projection in the vertical direction and the horizontal direction (accumulated value in one direction of the image data) is obtained, and the lung field portion is determined from this data by the anatomical region determining means. Are determined, and the determined region is set as the region of interest. Further, as disclosed in Japanese Patent Laid-Open No. 5-7578, the image data of each pixel is compared with a threshold value, and an identification code is added to each pixel based on the comparison result. An area is determined by performing labeling for each pixel group having a continuous code, and the determined area is set as a region of interest. Next, representative values D1 and D2 are set from the image data in the set region of interest, and processing for converting the representative values to desired levels S1 and S2 is performed. Further, a region for setting a representative value (hereinafter referred to as “signal region”) is extracted from the region of interest, and representative values D1 and D2 are set from the image data in the extracted signal region.

  As a method of extracting a signal region from this region of interest, a histogram of image data is created, and the signal region is extracted based on this histogram. For example, FIG. 5A shows a radiation image of a human hip joint part, and a region PA is a region where irradiation field stop is performed and radiation is not irradiated. FIG. 5B is a diagram in which irradiation field recognition is performed and a region in the recognized irradiation field is set as a region of interest. FIG. 5C shows a histogram of the image of this region of interest. A direct irradiation region PB in the region of interest shown in FIG. 5B is a region where the radiation is directly irradiated without passing through the subject, and the radiation dose is large. For this reason, the direct irradiation region PB corresponds to a region Pb having a high level of image data as shown in FIG. Further, the radiation shielding area PC in the region of interest (the area where radiation shielding is performed by a radiation protective device or the like) has a small radiation dose because the radiation is shielded. Therefore, the radiation shielding area PC corresponds to the area Pc having a low level of image data. Further, in the subject region PD within the region of interest, radiation is modulated by the subject, and the subject region PD corresponds to a region Pd between a region Pb having a high level of image data and a region Pc having a low level. As described above, since the subject area can be determined from the histogram of the image data, the high-level area Pb and the low-level area Pc shown in FIG. 5C are removed, and the area Pd is set as the signal area. .

  Further, in the extraction of the signal area, a method disclosed in Japanese Patent Laid-Open No. 63-262141 can be used. In this method, a histogram of image data is divided into a plurality of small areas by an automatic threshold selection method using a discrimination criterion method or the like, and a desired image portion is extracted as a signal area among the divided small areas.

  In the setting of the representative values D1 and D2, for example, a substantially minimum value and a substantially maximum value in the region of interest or the extracted signal region are used as the representative values. In addition, a signal value at which the cumulative histogram in the signal region becomes a predetermined value, for example, 20% and 80%, is used as the representative signal value. Further, assuming that one representative value is used, for example, a signal value at which the cumulative histogram in the signal region is 60% is used as the representative signal value. In the setting of the representative values D1 and D2, processing that is more suitable for the subject can be performed by using the image data in the signal region than in the case of using the image data in the region of interest.

  Thus, it has a region-of-interest setting means for setting a desired region of interest by analyzing the PCI radiographic image, and determines an image processing condition based on the image signal in the set region of interest, and performs processing based on that. Do. Since the image processing condition is determined by the image signal in the region of interest, the optimum processing condition can be determined.

  The region-of-interest setting means analyzes a normal captured image in the same manner to set a desired region of interest, determines an image processing condition based on the image signal in the set region of interest, and performs processing based on that. Can be done.

  Next, gradation processing is performed using the image data DTreg as shown in FIG. In the gradation processing, for example, a gradation conversion curve as shown in FIG. 6 is used, and the image data DTreg is converted into output image data DTout with the reference values S1 and S2 of the image data DTreg as levels S1 ′ and S2 ′. . These levels S1 'and S2' correspond to predetermined luminance or photographic density in the output image.

  The gradation conversion curve is preferably a continuous function over the entire signal region of the image data DTreg, and its differential function is also preferably continuous. Moreover, it is preferable that the sign of the differential coefficient is constant over the entire signal region.

  Further, since the preferable gradation conversion curve shape and levels S1 ′ and S2 ′ differ depending on the imaging region, imaging position, imaging conditions, imaging method, etc., the gradation conversion curve may be created for each image each time. Further, as shown in, for example, Japanese Patent Publication No. 5-26138, a plurality of basic gradation conversion curves are stored in advance, and any one of the basic gradation conversion curves is read out and rotated and translated. A desired gradation conversion curve can be easily obtained. As shown in FIG. 3, the image processing circuit 12 is provided with a gradation processing lookup table corresponding to a plurality of basic gradation conversion curves, and the gradation processing lookup table is referred to based on the image data DTleg. The output image data DTout subjected to tone conversion can be obtained by correcting the image data obtained in this way according to the rotation and translation of the basic tone conversion curve. In the gradation conversion process, not only the two reference values S1 and S2 but also one reference value or three or more reference values may be used.

  Here, the selection of the basic gradation conversion curve and the rotation and translation of the basic gradation conversion curve are performed based on the imaging region, imaging body position, imaging conditions, imaging method, and the like. When these pieces of information are input as management information using the input means 27, the basic gradation conversion curve can be easily selected by using this management information. Further, the levels of the reference values S1 and S2 may be changed based on the imaging region, the imaging posture, the imaging conditions, and the imaging method.

  Further, the selection of the basic gradation conversion curve and the rotation or translation of the basic gradation conversion curve may be performed based on information on the type of image display device and the type of external device for image output. This is because the preferred gradation may differ depending on the image output method.

  As methods other than the above for gradation conversion, JP-A-55-116339, JP-A-55-116340, JP-A-57-66480, JP-A-59-83149, JP-A-63-31641 are disclosed. JP-A-63-262141, JP-A-2-272529, JP-A-3-218578, JP-A-5-75925, JP-A-5-174141, JP-A-5-344423, JP-A-6-233755. JP-A-7-255012, JP-A-7-2711972, JP-A-8-62751, JP-A-8-331385, JP-A-9-261471, JP-A-9-266901, JP-A-10-32756, JP-A-10-63831, JP-A-11-88688, JP-A-11-316832, JP-A-2000-23950, JP-A-2000-30046, Open No. 2000-33082, it is possible to use a method described in JP 2000-79110, etc.. Of course, not only these methods but also various gradation conversion methods can be applied. Further, as the shape of the gradation conversion curve, for example, the one shown in Japanese Examined Patent Publication No. 63-20535 is used.

  As described above, since the processing conditions vary depending on whether or not the gradation processing is a PCI radiation image and other information, the image processing means 100 has gradation processing means for performing processing for converting gradation. .

  In addition, a gradation conversion curve storage unit that stores a plurality of gradation conversion curves is provided, and the gradation processing unit converts any one of the gradation conversion curves from the plurality of gradation conversion curves stored in the gradation conversion curve storage unit. A curve is selected, and gradation conversion is performed based on the selected gradation conversion curve.

  In the gradation processing means, a gradation conversion curve is selected from a plurality of gradation conversion curves stored in the gradation conversion curve storage means based on management information relating to photographing.

  Also, basic gradation conversion curve storage means for storing a plurality of basic gradation conversion curves is provided, and the gradation processing means selects any one of the plurality of basic gradation conversion curves stored in the basic gradation conversion curve storage means. Is selected, a desired gradation conversion curve is created by transforming the selected basic gradation conversion curve, and gradation is converted based on the created gradation conversion curve. .

  The gradation processing means selects a basic gradation conversion curve from a plurality of basic gradation conversion curves stored in the basic gradation conversion curve storage means on the basis of management information relating to photographing.

  The gradation processing means performs processing under the condition that the contrast coefficient for the PCI radiation image is smaller than the contrast coefficient for the normal captured image. The contrast coefficient refers to the gradient between two points on the characteristic curve when the horizontal axis is the logarithm of the X-ray dose and the axis is the signal value of the detector. As another definition of the contrast coefficient, a slope of a straight line connecting two points of a “curve density + 0.25” density point and a “fog density + 2.0” density point in the characteristic curve. . When the radiographic image is a PCI radiographic image, the image contrast is higher than that of a normal image, so the contrast coefficient in the gradation processing is set smaller, and as a result, the image has good graininess.

  Next, frequency enhancement processing and dynamic range compression processing will be described.

The image processing means 100 has frequency enhancement processing means for performing frequency enhancement processing. In this frequency enhancement process, for example, the function F is determined by the method shown in Japanese Patent Publication Nos. 62-62373 and 62-6237 in order to control the sharpness by the non-sharp mask processing shown in Expression (1).
Soua = Sorg + F (Sorg−Sus) (1)
Note that Soua is image data after processing, Sorg is image data before frequency enhancement processing, and Sus is unsharp data obtained by averaging the image data before frequency enhancement processing.

  In this frequency enhancement process, for example, F (Sorg-Sus) is set to β × (Sorg-Sus), and β (enhancement coefficient) is changed substantially linearly between the reference values S1 and S2 as shown in FIG. .

  Further, as shown by the solid line in FIG. 8, when low luminance is emphasized, β from the reference value S1 to the value “A” is maximized, and the value from “B” to the reference value S2 is minimized. In addition, from the value “A” to the value “B”, β changes almost linearly. When emphasizing high luminance, as indicated by a broken line, β from the reference value S1 to the value “A” is minimized and maximized from the value “B” to the reference value S2. In addition, from the value “A” to the value “B”, β changes almost linearly. Although not shown, when medium luminance is emphasized, β of values “A” to “B” is maximized. As described above, in the frequency enhancement processing, the sharpness of an arbitrary luminance portion can be controlled by the function F.

  Here, the reference values S1 and S2 and the values A and B are obtained by the same method as the determination method of the reference values S1 and S2 in the setting of the frequency enhancement processing conditions described above. Further, the method of frequency enhancement processing is not limited to the above-mentioned non-sharp mask processing, and Japanese Patent Application Laid-Open Nos. 55-87953, 55-163472, 56-104645, and 5-174141. JP-A-5-252444, JP-A-6-233755, JP-A-6-235882, JP-A-7-21364, JP-A-7-51257, JP-A-7-160876, JP-A-10-63812, Japanese Patent Application No. 2000-4398, Japanese Patent Application No. 4-048825, Japanese Patent Application No. 7-42277, Japanese Patent Application No. 7-73433, Japanese Patent Application No. 7-73497, Japanese Patent Application No. 7-94693, Japanese Patent Application No. 7-316679, JP-B-62-62373, JP-B-62-62376, JP-B-62-62379, etc., and a multi-resolution method (Japanese Patent Laid-Open No. 5-244). 08 No., it is possible to use No. 6-301766, JP-A-9-44645). Of course, not only these methods but also various frequency enhancement processing methods can be applied.

  Further, in the frequency enhancement process, the frequency enhancement process condition may be determined based on the management information related to photographing, and the process may be performed based on the condition.

  In the frequency enhancement process, the frequency band to be enhanced and the degree of enhancement are set based on the imaging region, imaging position, scanning conditions, imaging method, etc., as in the selection of the basic gradation conversion curve in the gradation processing. Is done.

  In this frequency enhancement process, the degree of enhancement for the PCI radiation image is smaller than the frequency enhancement coefficient for the normal captured image. The degree of emphasis is β of the coefficient in equation (1). When the radiographic image is a PCI radiographic image, the radiographic image contains more high-frequency components than the normal radiographed image. Therefore, the frequency emphasis coefficient in the frequency emphasis processing is set smaller, and as a result, the noise of the high-frequency components can be reduced. .

Further, the image processing unit 100 includes a dynamic range compression processing unit that performs a dynamic range compression process. In this dynamic range compression processing, the function G is determined by the method disclosed in Japanese Patent Publication No. 266318 in order to perform control within the density range that is easy to see by the compression processing shown in Expression (2).
Stb = Sorg + G (Sus) (2)
Note that Stb is processed image data, Sorg is image data before dynamic range compression processing, and Sus is unsharp data obtained by averaging the image data before dynamic range compression processing.

  Here, as shown in FIG. 9A, when G (Sus) has such a characteristic that G (Sus) increases when the unsharp data Sus becomes smaller than the level “La”, the low density region The image data Sorg shown in FIG. 9B is image data Stb in which the dynamic range on the low density side is compressed as shown in FIG. 8C. In addition, as shown in FIG. 9D, when G (Sus) has such characteristics that G (Sus) decreases when the unsharp data Sus becomes smaller than the level “Lb”, It is assumed that the density is high, and the dynamic range on the high density side of the image data Sorg shown in FIG. 9B is compressed as shown in FIG. 9E. Here, the levels “La” and “Lb” are obtained by the same method as the method for determining the reference values S1 and S2 in the setting of the gradation processing conditions described above.

  In the dynamic range compression processing, the correction frequency band and the degree of correction are set based on the imaging region, the imaging posture, the shadowing condition, the imaging method, and the like.

  As described above, according to the above-described embodiment, it is possible to always stably obtain a radiation image having a density and contrast suitable for diagnosis by performing gradation processing on the obtained image data. By the dynamic range compression processing, it is possible to obtain a radiation image within an easy-to-view density range without reducing the contrast of the fine structure portion of the subject.

  Thus, in the dynamic range compression process, the degree of correction for the PCI radiation image is larger than the coefficient for the normal captured image.

The function G in Expression (2) and FIG. 9A is, for example, G = β · (La−Sus)
β: Constant Sus ≦ Laβ = 0 Sus> La.

  The degree of correction is the coefficient β in equation (2). A large degree of correction means that β is large or La is large.

  When the radiographic image is a PCI radiographic image, the sharpness is better than that of a normal image, so that even if the coefficient in the dynamic range compression process is set larger, the sharpness can be prevented from being lowered.

  As methods of dynamic range compression processing, methods other than those described above are disclosed in JP-A-63-190443, JP-A-63-189854, JP-A-3-222577, JP-A-5-174141, and JP-A-5-300376. JP-A-6-1211795, JP-A-6-292008, JP-A-6-292009, JP-A-6-292013, JP-A-6-339025, JP-A-7-38758, JP-A-8-294006, The methods described in JP-A-9-266901, JP-A-11-41541, JP-A-11-191150, JP-A-11-191150, and the like can be used. Of course, not only these methods but also various gradation conversion methods can be applied.

  Further, in the dynamic range compression processing, dynamic range compression processing conditions may be determined based on management information relating to shooting, and processing may be performed based on the dynamic range compression processing conditions.

  Next, an embodiment of the radiation image processing apparatus will be described.

  First, energy subtraction will be described. A specific structure is obtained by irradiating the same subject with radiation having different energy distributions, and a specific structure (eg, organ, bone, blood vessel, etc.) of the subject has a specific radiation energy absorption characteristic. After obtaining two image signals drawn differently, the two image signals are appropriately weighted and then subtracted between the two signals to extract an image of a specific structure.

  A specific method of this energy subtraction is, for example, by performing one-shot energy subtraction in which two detectors simultaneously record radiation images carrying a high-energy component and a low-energy component of radiation, respectively, and a radiation image of a subject from each detector. Is obtained, and an image in which a specific structure of the subject is emphasized is obtained by performing a subtraction process between the image signals. Further, in order to obtain a plurality of radiation images, it is not always necessary to have one shot, and a plurality of shots may be used.

  FIG. 10 is a diagram showing a configuration of a PCI radiation image processing apparatus. In the PCI radiographic image processing apparatus of this embodiment, the radiographic image reader has detector constituent units 140 and 141. The detector structural units 140 and 141 are configured by a detector including solid-state photodetectors 140b and 141b stacked with planar scintillators 140a and 141a, respectively.

  The radiation 105 emitted from the radiation source 130 is applied to the subject 106 and passes through the subject 106. The radiation 105 that has passed through the subject 106 is irradiated to the detector constituent unit 140 of the radiation image reader. The radiation 105 irradiated to the detector structural unit 140 is first irradiated to the scintillator 140a.

  The scintillator 140a emits visible light having an intensity corresponding to the intensity of the irradiated radiation 105 and is received by the solid-state photodetector 140b. The visible light is photoelectrically converted and signal charges are accumulated in the solid-state photodetector 140b according to the emission intensity. Thereafter, the signal charges are read from the transfer unit, and an image signal SA as an electric signal is output. This image signal SA is an image signal of a normal captured image.

  On the other hand, among the radiation 105 irradiated to the detector structural unit 140, the radiation that has not been converted by the scintillator 140a passes through the solid-state photodetector 140b and reaches the detector structural unit 141, and becomes visible light by the scintillator 141a. The light is converted and received by the solid-state photodetector 141b. Then, the visible light is photoelectrically converted, and signal charges are accumulated in the solid-state photodetector 141b according to the emission intensity. Thereafter, this signal charge is read from the solid-state photodetector 141b, and an image signal SB as an electric signal is output. This image signal SB is an image signal of a PCI radiation image.

  In this embodiment, a plurality of radiographic images are taken by one X-ray irradiation, and subtracted images are obtained from these images. A plurality of detectors are arranged behind the subject, and a plurality of images are obtained simultaneously by one X-ray irradiation. Since the plurality of radiographic images are images having the same shape, there is no shape shift when the images are aligned.

  In addition, as shown in FIG. 11, a filter 143 containing a low energy component absorbing substance of radiation can be interposed in at least one place between detector structural units 140 and 141 which are detectors of the radiation image reader. .

  Specifically, it is preferable to arrange the detector structural unit 140 immediately after the solid-state photodetector 140b. Since the filter 143 contains an X-ray low energy component absorbing material, the X-rays transmitted through the filter 143 are in a state in which the low energy component is reduced and the high energy component is included. For this reason, the detector structural unit 141 receives information in which the image information related to the low energy component of the X-rays is reduced as compared with the detector structural unit 140.

  On the other hand, a detector with different energy absorption characteristics may be used instead of the above. In that case, a detector having a high absorption characteristic of a low energy component is used closer to the radiation source 130.

The output image signals SA and SB are input to the control unit 150 and given a predetermined weight, and a difference is performed. That is, S = k1 · SA + k2 · SB (3)
However, k1, k2: a weighting coefficient is calculated, and an image signal S is obtained (because of the difference, k1 or k2 is a negative value here). Further, image processing or the like is performed on the image signal S, and the processed image signal S ′ that has been processed is input to the output unit 151, for example, and a radiographic image of the subject 106 is output as a visible image.

  It is preferable to have a weighting unit that performs predetermined weighting on the plurality of radiation images obtained in this way, and weights each image so that a difference can be made while leaving a necessary part. That is, when two images which are preferable modes are used, a predetermined difference image can be obtained by performing a subtraction process between SA which is a signal of a normal captured image and SB which is a signal of a PCI radiation image.

  The control unit 150 includes a size alignment processing unit 150c that performs size and alignment of a plurality of images. Since the size of the image differs between the PCI radiation image and the normal image, it is necessary to accurately match the size and position of the image to be used. Since the size changes, the corresponding pixel changes. In order to match the corresponding pixels, it is necessary to perform an interpolation process.

  In the case where the photographing information storage unit 152 stores the management information related to photographing, and the management information related to photographing includes an enlargement ratio, the enlargement ratio information and the size of a plurality of images are combined by arbitrary interpolation processing, and then Perform alignment processing.

  As a positioning method, there are a parallel movement method and a template matching method, a method of aligning the positions of the markers by simultaneously photographing the markers and the like.

  As shown in FIG. 12, the template matching method is such that the center of a template t (x, y) representing an object to be detected overlaps with a point (i, j) in an image f (x, y). In this method, the similarity between t (x, y) and the partial pattern of the overlapping image is measured, and that value is used as the probability that the object exists at the point (i, j) (Computer Publishing Co., Ltd. (Introduction to image processing, see page 149).

  As a method for aligning the positions by simultaneously photographing the markers and aligning the positions of the markers, those described in JP-A-6-22219 and JP-A-10-108073 can be used.

  In Japanese Patent Laid-Open No. 6-22219, relative alignment of X-ray images carried by two image signals SO1 ′ and SO2 ′ is performed on the image signal (Japanese Patent Laid-Open No. 58-163338). This alignment is performed by relatively linearly moving and rotating the two X-ray images so that the two marks 500 shown in FIG. 13 overlap.

  Japanese Patent Application Laid-Open No. 10-108073 discloses an alignment process in which a predetermined alignment marker is imprinted when a target image is photographed, and the document Medical is used. Imaging Technology (Medical Imaging Technology) Vol. 11No. 3 July 1993pp. Various known methods such as alignment processing by two-dimensional nonlinear image deformation shown in 373 to 374 can be applied.

  Further, in this embodiment, when the photographing information storage unit 152 that stores the management information related to photographing is included and the magnification information is not included in the management information related to photographing, the magnification rate is obtained and obtained based on the analysis result. The sizes of the plurality of images are matched by the enlargement ratio and an arbitrary interpolation process, and then the alignment process is performed.

  As an analysis method for obtaining the enlargement ratio, there is a method for obtaining distances of a part or the whole of a plurality of markers or subjects and obtaining the enlargement ratio from the ratio of the distances. In this case, both automatic and manual are conceivable. Part of the subject includes the length of the lung width. As another method, it is conceivable to change the enlargement ratio little by little to match the other image and obtain the most suitable magnification. Even if the enlargement ratio is not known, if the management information has R1 and R2, the enlargement ratio can be obtained by the enlargement ratio = 1 + R2 / R1.

  The control unit 150 includes subtraction processing means 150a that performs subtraction processing of a plurality of radiographic images including at least one PCI radiographic image captured on the same subject 106 to obtain subtraction images, and each of the plurality of detectors receives radiation. Perform one-shot energy subtraction to record (simultaneously) a radiographic image carrying a high energy component and a low energy component, obtain an image signal carrying a radiographic image of the subject from each detector, and perform subtraction processing between each image signal Thus, an image in which a specific structure of the subject is emphasized can be obtained.

  Since the PCI radiation image is particularly excellent in the ability to depict blood vessels and the like, for example, it is possible to extract a site such as a blood vessel based on a difference from a normal captured image. As a result, it is possible to take an image taken by angiography without using a contrast agent.

  In this embodiment, it is desirable to create a difference image with two images of normal shooting and PCI shooting.

  In this embodiment, since the image quality differs between the normal captured image and the PCI radiographic image, that is, the contour of the blood vessel etc. is clearly displayed on the PCI radiographic image, so it is not necessary to prepare a detector having different characteristics in particular, and the same energy absorption. A characteristic detector may be used. Of course, detectors having different energy absorption characteristics may be used, or X-ray energy may be converted.

  As a specification of this PCI radiographic image processing apparatus, it is preferable that the object holder, that is, the human body does not move and the detector and the radiation source move. It is easier for the subject person to set the distance by moving the detector without moving the human body. There are two detectors, one for normal shooting and one for PCI shooting. The detector for normal shooting is fixed at the subject holder position, and the one for PCI shooting is a fixed distance away from the subject holder position and can be moved. It is preferable.

  Further, in the above-described embodiment, the radiation image reader composed of a combination of a scintillator and a solid-state photodetector is used. However, the present invention is not limited to this, and each type of radiation image reader described above is used. Can be used.

  In the radiation image reader described above, a filter that absorbs a low-energy component of radiation is arranged between each detector constituent unit. However, any scintillator between each detector constituent unit may be used. You may make it interpose in a position.

  Further, in the above-described embodiment, it is used for obtaining a radiographic image of a subject by detecting radiation irradiated through the subject. However, the present invention is not limited to this. The present invention can also be applied to so-called autoradiography in which a radiation image of a subject is obtained by detecting radiation emitted from itself.

  Next, another embodiment of the radiation image processing apparatus will be described.

  FIG. 14 is a diagram showing the configuration of the radiation image processing apparatus. The PCI radiographic image processing apparatus according to this embodiment is configured in the same manner as the embodiment shown in FIG. 10, but instead of the subtraction processing means 150a of the embodiment shown in FIG. An addition processing unit 150b that performs addition processing of a plurality of radiographic images including at least one PCI radiographic image captured with respect to 106 to obtain an addition image is provided. The PCI radiographic image is an image with high sharpness, but by further adding the images, it is possible to obtain an image with less noise components and good graininess.

  In this embodiment, a plurality of radiation images are taken by one X-ray irradiation, and an added image is obtained from these images. A plurality of detectors are arranged behind the subject, and a plurality of images are obtained simultaneously by one X-ray irradiation. Since the plurality of radiographic images are images having the same shape, there is no shape shift when the images are aligned.

  Weighting means for performing predetermined weighting on the plurality of obtained radiographic images is provided, whereby each image is weighted according to the equation (3).

  In addition, a size alignment processing unit 150c that performs size alignment of a plurality of images is provided. Since the size of the image differs between the PCI radiation image and the normal image, it is necessary to accurately match the size and position of the image to be used. Since the size changes, the corresponding pixel changes. In order to match the corresponding pixels, it is necessary to perform an interpolation process.

  In the case where the photographing information storage unit 152 stores the management information related to photographing, and the management information related to photographing includes an enlargement ratio, the enlargement ratio information and the size of a plurality of images are combined by arbitrary interpolation processing, and then Perform alignment processing.

  As a method of aligning and adjusting the size, the same method as described above is performed.

  The PCI radiation image processing apparatus includes both the subtraction processing unit 150a of the embodiment shown in FIG. 10 and the addition processing unit 150b of the embodiment shown in FIG. 14, and images the same subject 106 as necessary. In addition, a subtraction process may be performed on a plurality of radiographic images including at least one PCI radiographic image to obtain a subtraction image, and an addition process may be performed on the plurality of radiographic images to obtain an addition image.

  Next, another embodiment of the PCI radiation image output apparatus will be described.

  The PCI radiation image output apparatus of this embodiment is shown in FIG. The PCI radiographic image output apparatus according to this embodiment is configured in the same manner as the embodiment shown in FIG. 1, but has an output unit 60 that outputs an enlarged radiographed PCI radiographic image at a reduction ratio α or more and 1 or less. The reduction ratio α is a reduction ratio for making the captured image the same size as the subject, that is, the reciprocal of the enlargement ratio of the captured image. Since the PCI radiographic image is enlarged, the subject on the image becomes large. However, it is preferable that the PCI radiographic image has a size that is familiar from the viewpoint of diagnosis. In particular, it is desirable to output the subject and the actual size. Needless to say, even if the reduction ratio of the image output is set as default as described above, it is a digital image and can be changed as desired by the user.

  After appropriate image processing is performed by the control unit 10, a hard copy can be obtained by using an image output device such as a laser imager as the output unit 60. At this time, for example, it is preferable that the control unit 10 sends image data to the laser imager to automatically reduce the image to a predetermined size and output the image.

  Moreover, as an output means, the thing equivalent to what was described in embodiment of the above-mentioned PCI radiographic image processing apparatus and PCI radiographic image detection processing apparatus can be used.

  The PCI radiographic image output apparatus according to this embodiment also includes an interpolation processing condition storage unit 61 that stores a plurality of interpolation processing conditions. The output unit 60 stores a plurality of interpolations stored in the interpolation processing condition storage unit 61. One of the interpolation processing conditions is selected from the processing conditions, and interpolation processing is performed using the selected interpolation processing condition to output a radiation output image.

  The interpolation process is at least one interpolation process selected from nearest neighbor interpolation, linear interpolation, spline interpolation, cubic convolution interpolation, and bell spline interpolation.

  Moreover, it has the imaging | photography information storage means 62 which memorize | stores the management information regarding imaging | photography, can determine an interpolation process condition based on the information of the management information regarding imaging | photography, and can perform an interpolation process based on it. For example, based on the information of the magnification A of the photographed image, if the image is to be output in actual size, the image is output after being multiplied by 1 / A. By having management information related to imaging, an optimal image processing condition is determined based on the management information related to imaging, processing is performed, and an image suitable for diagnosis can be obtained. For example, from the information of R1 and R2, the enlargement ratio M can be obtained as M = 1 + R2 / R1, and the image is reduced to 1 / M times and output. Specifically, when the sampling pitch of the input device is 100 μm and the image is reduced by half and output, the sampling pitch of the image is set to 50 μm (= 100 μm × 1/2), and thereafter the same method as usual. It is possible to use a method such as

  In this embodiment, the interpolation processing is performed based on the sampling pitch of the input means 27, the sampling pitch of the output means 60, and the information on the magnification of the photographed image, and the photographed subject is output at the same magnification. preferable.

  The size of the output image that is most easily diagnosed is the same size as the subject. As described above, the size of one pixel of the output image is determined by dividing the sampling pitch of the input means 27 by the enlargement ratio of the image. This size is compared with the size of the sampling pitch of the output means 60, interpolation processing is performed as necessary, and a final image is output.

  Image processing means for creating image data output from the output means 60 from information such as the sampling pitch of the input means 27, the sampling pitch of the output means 60, the enlargement ratio (reduction ratio) of the output image with respect to the input image, and the interpolation processing conditions. 63, the image processing means 63 may be provided in the control unit 10 or may be provided in the output means 60 for processing.

  Also, the designated information of the management information related to photographing is attached to the output image and output. Attaching the enlargement ratio of the photographed image or the reduction ratio, which is the inverse of the enlargement ratio, is helpful during diagnosis.

  The image output means that an image is printed out on a film, paper, or the like, and is not displayed on a CRT or the like.

  Here, the sampling pitch is a pixel interval and is usually the same size as the pixel size.

  In outputting a plurality of images, there is also a method of outputting the same magnification and partially enlarged images side by side. In this case, it is easy to understand if the enlarged portion is displayed in the same size image. As an image output method, there is one equal-size image, an equal-size image and a partially enlarged image in parallel, and the like.

  In addition to the above, the display method on the CRT and the like includes one normal-size image, a normal-size image and a partially enlarged image in parallel, and the like. In the case of CRT, after displaying the default image, the user can freely change and observe.

  Next, another embodiment of the PCI image diagnosis support apparatus will be described.

  For example, when a doctor makes an image diagnosis using a radiographic image, an X-ray image is displayed on an image display device such as a CRT to perform interpretation. In recent years, technology has been developed to detect abnormal shadows such as lung cancer and breast cancer by analyzing image data using computerized digital image processing technology, and presenting detected abnormal shadow candidate information to doctors It has become possible to provide support.

  An embodiment of such an image diagnosis support apparatus is shown in FIG. The PCI image diagnosis support apparatus of this embodiment includes an image data input means 602, an image output control signal input means 603, an image processing means 604, an image storage means 605, an abnormal shadow candidate detection means 606, an abnormal shadow storage means 607, an image. An output control unit 610, an image display unit 608, and an image print unit 609 are provided. A photographing information storage unit 652 is connected to the image processing unit 604.

  As for the input of image data from the image data input means 602, for example, in a mass examination, radiographic images are usually taken using an X-ray film. In order to input these X-ray photographs to the system of this embodiment, a laser digitizer is used. In this method, a film is scanned with a laser beam, the amount of transmitted light is measured, and the value is converted into analog to digital data, which is input as digital image data.

  An apparatus using an optical sensor such as a CCD can also be used for image input. It is also possible to connect a photographing device capable of directly outputting a digital image using a stimulable phosphor as described in JP-A-55-12429, instead of reading a film. .

  It is also possible to manually operate an X-ray image obtained from a flat panel detector (FPD) that captures an X-ray image by a plurality of two-dimensionally arranged detection elements and outputs it as an electrical signal. Since these detectors are described in detail above, they are omitted here.

  When a digital X-ray image is obtained with the above-described various configurations, the effective pixel size of the image is preferably 200 μm or less, for example, 100 μm or less, for example, for a mammogram, depending on the imaging region and diagnostic purpose. More preferably. In order to maximize the performance of the image diagnosis support apparatus of the present invention, it is preferable to store and display image data input with an effective pixel size of about 50 μm, for example. The pixel size of the image data used for the analysis for detecting the abnormal shadow candidate in the abnormal shadow candidate detecting means does not need to be equal to the pixel size of the input image. For example, the effective pixel size of the input image is set to 50 μm, and the abnormal shadow is detected. As the image data used for candidate detection, the input image may be thinned and converted to an effective pixel size of 100 μm.

  In the image storage means 605, the input image data is subjected to data compression as necessary and stored. Here, as the data compression, lossless compression or lossy compression using a known method such as JPEG, DPCM, or wavelet compression is used. Lossless compression is preferable because there is no deterioration of diagnostic information associated with data compression.

  In small-scale diagnosis, the amount of data is not so large, so that the image data can be stored on the magnetic disk without being compressed. In this case, image data can be stored and read out much faster than the magneto-optical disk. At the time of image interpretation, since a fast cycle time is required, necessary image data is also stored in a semiconductor memory.

  The images stored in the image storage unit 605 are sequentially read out, image processing is performed by the image processing unit 604, and abnormal shadow candidates are detected by the abnormal shadow candidate detection unit 606.

  The abnormal shadow candidate detection unit 606 analyzes the image data read from the image storage unit 605, thereby detecting, for example, a microcalcification cluster and a mass shadow as shown in FIG. FIG. 17A shows an example of a microcalcification cluster. The presence of microcalcifications in a cluster (clustered) is one of the important findings for finding early breast cancer because it is likely to be early cancer. On the mammogram, it appears as a small white shadow with a generally conical structure. Moreover, the mass shadow shown in FIG. 17B is seen as a whitish and round shadow close to a Gaussian distribution on a lump or mammogram having a certain size.

  Thus, two major findings of breast cancer are a mass shadow and a microcalcification cluster, and a method for detecting a mass shadow by comparing left and right breasts (Med. Phys., Vol. 21. no). .3, pp. 445-452) and a method of detecting using an iris filter (Science Theory (D-11), Vol. J75-D-11, no. 3, pp. 663-670, 1992), Method of detection using a Quioit filter (Science theory (D-11), Vol. J76-D-ll, no. 3, pp 279-287, 1993), binary based on a histogram of pixel values of divided breast regions Detection method (JAMIT Frontier 95 Proceedings, pp84-85, 1995), minimum taking the minimum output of many directional Laplacian filters Direction differential filter (IEICE (D-ll), Vol.J76-D-ll, no.2, pp.241-249,1993), and the like.

  As a method for detecting microcalcification clusters, a region suspected of calcification is localized from the breast region, and false positive candidates are deleted from the optical density difference of the shadow image, the standard deviation of the boundary density difference, or the like (IEEE). Trans Biomed Eng BME-26 (4): 213-219, 1979), a method of detection using images subjected to Laplacian filter processing (Science theory (D-ll), Vol. J71-D-ll, no. 10, pp. 1994-2001, 1988), a detection method using a morphologically analyzed image to suppress the influence of a background pattern such as a mammary gland (Science theory (D-ll), Vol. J71-D-ll.no). 7, pp. 1170-1176, 1992).

  The image to be displayed is an image processed by the image processing means 604. What is subjected to image processing by the image processing means 604 includes any one of gradation processing, frequency enhancement processing, and dynamic range compression processing. In particular, the gradation processing includes image processing that is characterized in that even if a microcalcification cluster exists in any region in the breast, it is output with a stable contrast. Further, the frequency enhancement processing includes, in particular, a feature that creates a distance function from the skin line and performs dynamic range compression based on the distance function. The image processing is characterized in that image processing under the same conditions is performed in the same direction and / or the same breast of the same patient. The image processing may determine conditions for each image, or may be determined according to predetermined conditions.

  When a plurality of images are displayed on the image display means 608 at the same time, it is preferable to perform image processing under the same conditions for all of the plurality of images.

  a. In gradation processing, gradation conversion curves representing the correspondence between original image data (input) and gradation processed image data (output) are determined based on the analysis result of the image data, and this gradation conversion is performed. Tone processing is performed using a curve.

  Prior to gradation processing, if irradiation field recognition processing is performed to detect the radiation field area, it is necessary for diagnosis by setting various image processing conditions using the image data in the recognized irradiation field area. This is preferable because image processing of the image portion can be appropriately performed.

  MEDICAL IMAGEING TECHNOLOGY Vol. No. 14 6 November 1996 Based on pages 66 to 671, a contrast correction curve capable of correcting the contrast of microcalcification images existing in various regions to substantially the same level is created. By converting the pixel values of all the pixels on the breast region image using this correction curve, the density gradation of the low-density area of the breast and mass where the contrast becomes small is enlarged. On the contrary, correction is performed so as to compress the density gradation of the fat area where there is little possibility that a microcalcification image exists.

  This contrast correction process is effective in that it not only contributes to the improvement of the automatic detection performance but also facilitates visual observation in the mammary gland tissue, and can also be applied as an image processing method.

  b. Frequency enhancement processing In frequency enhancement processing, the sharpness of an image can be controlled by means such as non-sharp mask processing or a multi-resolution method.

  c. Dynamic range compression processing In the dynamic range compression processing, the dynamic range compression of an arbitrary signal region can be performed using, for example, the technique disclosed in Japanese Patent No. 2509503 or Japanese Patent No. 2663189. As another example, a distance function from a skin line in a mammogram is created, and dynamic range compression is performed based on the distance function.

  There is a high possibility that the skinline will be crushed because it is very dense. This is because the mammogram imaging method captures the breast. When photographing with the breast sandwiched, the thickness of the breast is not sufficient in the vicinity of the skin line, so that X-rays pass through a thin human body region compared to other parts, and the transmittance is increased. Also, as the skin line is approached, the thickness of the breast becomes thinner. For this reason, a dynamic range is compressed by creating a distance function determined by the distance from the skin line and reducing the pixel value near the skin line in accordance with the distance function. Processing condition changing means for changing processing conditions of gradation processing, frequency enhancement processing, and dynamic range compression processing may be provided, and the changed conditions may be stored.

  In the image output control signal input means 603, for example, the gradation that can be changed and the contrast of a portion that may be a lesion can be changed to a gradation that can be more easily diagnosed by using a mouse attached to the image display means 608. it can. In this case, since the contrast continuously changes with the vertical movement of the mouse and the brightness changes with the horizontal movement, it can be easily changed to a desired gradation. In addition to the image enlargement processing, other operations such as image switching and gradation change can be performed by operating the mouse. The image is enlarged by hardware, and can be instantly enlarged to an arbitrary magnification by the movement of the mouse around the place pointed by the pointer. Further, since interpolation processing is performed, even if enlarged, it does not become a mosaic and can be easily diagnosed. The image processing conditions determined as described above may be stored.

  For example, in group screening, images are read in 5 to 20 seconds per image, and the images are switched one after another. By pointing the button-like area set at the upper right of the screen with the pointer and pressing the mouse button, Switch. Normally, it is simply switched to the next image in order, but it is also possible to return to the previous image by clicking on an adjacent area.

  The doctor interprets the displayed image data. If an abnormality is found as a result of the interpretation, it is possible to input by indicating the location where the abnormality was found on the display image, and store the input finding information in the finding information storage means.

  As the image display means 608, known image display means such as a CRT, a liquid crystal display, a plasma display or the like can be used. Among them, a high-definition and high-intensity CRT dedicated to medical images or a liquid crystal display is most preferable. Furthermore, a high-definition display having about 1000 × 1000 or more display pixels is preferable, and a high-definition display having about 2000 × 2000 or more display pixels is most preferable.

  Further, each of the displayed images has display control number input means for controlling the display position of the image, the inversion of the image, and the rotation of the image. For each of the displayed images, the display position of the image, the image By reversing the image and rotating the image, it is possible to compare and study images from various directions, and easily and quickly perform accurate image diagnosis using medical images.

  The image output control unit 610 outputs an image to the image display unit 608 or the image print unit 609 based on the image output control signal of the image output control signal input unit 603.

  The image data read from the image storage unit 605 is displayed on the image display unit 608. The image display means 608 is switched and displayed as shown in FIG. 18, and is divided into at least two groups including all images display mode for displaying all mammogram images at the same time and all images, and included in this group. Display mode switching means for switching between the respective display modes.

  In this embodiment, there is provided display mode switching means for switching and displaying the image display mode according to a predetermined order. The CRT 620 is a four-part display (all-image display) in which the first screen a has the same imaging direction of the left and right breasts, for example, the captured CC images in the vertical direction of the left and right breasts face each other, and the captured MLO images in the diagonal direction face each other. ) Is performed. Next, it is divided into two series. In the b series, a two-part display (group display) in which the MLO images of the left and right breasts are opposed to each other in the display b1, and a two-part display in which the left and right breast CC images are opposed to each other in the display b2. The right breast CC image and the MLO image are divided into two divided displays, the display b4 is the left breast CC image and the MLO image are divided into two divided displays, and the display b5 is finally opposed to the left and right breast CC images. Further, in the four-segment display in which the MLO images are opposed to each other, the mark 621 is added and displayed at the abnormal shadow candidate position of the image, and then the display returns to the first image display.

  Further, in the c series, the left and right breast CC images are opposed to each other in the display c1, and the MLO image is opposed to each other, and the display is performed by adding the mark 621 to the abnormal shadow candidate position of the image, and the display c2 is the left and right breasts. 2 split display with the left and right breast CC images facing each other on the display c3, 2 split display with the right breast CC image and the MLO image facing each other on the display c4, and left on the display c5 The breast CC image and the MLO image are displayed in two-divided views, and then the display returns to the first image display.

  The difference between the two series b and c is whether the abnormal shadow detection means is displayed at an early stage or at a later stage. When displaying at an early stage, the abnormal shadow detection result pointed out by the computer can be read with particular care, which helps to reduce the burden on the doctor. When the image is displayed at a later stage, the abnormal shadow detection result is displayed after the doctor makes a diagnosis, so there is an effect of double interpretation, which helps to reduce oversight. In addition, since the two sequences can be freely changed, the selection can be made according to the preference of the doctor, the diagnosis situation, etc., which helps to improve the diagnostic performance.

  Further, the images included in the group include at least two images having different imaging directions of the left breast of the same patient, at least two images having different imaging directions of the right breast of the same patient, or imaging directions of the left breast and the right breast of the same patient. Are at least two images different from each other, or at least two images in which the imaging directions of the left breast and the right breast of the same patient are the same.

  In this way, by performing all-image display that displays mammogram images of all images at the same time and group display that displays all the images included in this group by dividing the all images into at least two groups including a plurality of images. Two groups of images can be compared and interpreted, and diagnosis can be performed quickly, easily and accurately.

  In addition, since the display mode switching means for switching and displaying the image display mode according to a predetermined order is provided and the image display mode is switched and displayed in the predetermined order, for example, without giving a foresight to the doctor. Alternatively, the images can be compared without omission, and the medical image can be used for easy, quick and accurate image diagnosis.

  In addition, diagnostic order storage means for storing the order of image diagnosis in advance is provided, and the display mode is switched and displayed according to the order of image diagnosis. In this way, the order of image diagnosis is stored in advance, and the display mode is switched according to the order of image diagnosis, so that the order of preference can be set and diagnosed for each doctor, improving diagnostic performance. It can be useful for quick and accurate diagnostic imaging.

  Further, the image display means 608 is provided with an operation display 640 constituted by a touch panel as shown in FIG. The touch panel includes a quad display key 640a, a right breast display key 640b, a left breast display key 640c, an MLO image display key 640d, a CC image display key 640e, an all detection display key 640f, a mass display key 640g, a calc display key 640h, A cluster display key 640i is provided.

  By operating the display mode selection means 641a using the quadrant display key 640a, the right breast display key 640b, the left breast display key 640c, the MLO image display key 640d, the CC image display key 640e, etc., image display necessary for image diagnosis is performed in advance. Arrangement is determined, and each shooting direction and display direction can be freely selected. In this way, the arrangement of image display necessary for image diagnosis is determined in advance, and each imaging direction and display direction can be freely selected. For example, a doctor can freely display images and the like for comparison. Thus, it is possible to easily and quickly perform an accurate image diagnosis using a medical image.

  Further, the mammogram detection result is displayed by the detection result display means 641b such as the all detection display key 640f, the mass display key 640g, the calc display key 640h, and the cluster display key 640i. The all detection display key 640f displays all detection results, the mass display key 640g is operated for mass shadow mass detection results, the calc display key 640h is operated for microcalcification calc detection results, and the cluster display key 640i is operated. Display of the detection result of micro calcification.

  In addition, after displaying the detection result by pressing the necessary key, for example, by pressing the same key, the display result can be easily erased, so that only the necessary result is displayed, which is useful for diagnosis. be able to.

  Further, by switching to one of the switching methods of switching the display mode of the image according to a predetermined order and the switching method of switching to the display mode selected by the display mode selection unit 641a described above, for example, a doctor Can compare images without foreseeing or without omission, or can display and compare images that doctors need freely, and can easily, quickly and accurately use medical images Image diagnosis can be performed.

  In addition, patient information and examination information are stored in association with images, and multiple images of the same patient and the same examination are displayed. For example, by comparing each image, it is easy, quick and accurate using medical images. Image diagnosis can be performed.

  The patient information is preferably a relatively dark color. If the color is bright, the doctor's eyes may become tired, and the diagnostic performance may deteriorate.

  In addition, the display position or the display image orientation can be determined according to the imaging direction and the right and left breasts for images included in the same patient and the same examination image group, and the images are compared and examined from various directions. Thus, it is possible to easily and quickly perform an accurate image diagnosis using a medical image.

  Further, as shown in FIGS. 18 and 20, the image of the left breast and the image of the right breast of the same patient and in the same photographing direction can be arranged and displayed side by side with the nipple facing outward. In this way, the left breast image and the right breast image of the same patient and in the same imaging direction are displayed side by side so that the nipples face outward, making it easier and faster to compare the images. Accurate image diagnosis can be performed.

  Also, trim the nipple side. By trimming the nipple side of the image in this way, the image size can be reduced, which has the effect of improving display speed and saving memory. In addition, by displaying the patient information 55 on a part of the region where the subject on the nipple side of the image is not shown, the patient information and the subject can be displayed without being overlapped, so that diagnosis can be performed easily and accurately. .

  In addition, the left and right breasts are aligned in the vertical direction, and the left and right breasts are aligned in the vertical direction, so that the image is displayed accurately in a symmetrical state and the left and right breasts can be easily compared. Therefore, improvement in diagnostic performance can be expected.

  The vertical positioning of the left breast and the right breast is performed by automatic positioning means. In this embodiment, as shown in FIG. 20, the left and right breasts in the same imaging direction are aligned based on the skin lines 660 and 661 of the image. The breast skin lines 660 and 661 are substantially symmetrical with respect to the chest wall 667 direction in an image in the same photographing direction. It is possible to match the left and right breasts at a position where the shape of the skin line is compared and the cumulative absolute value difference of the distance from the chest wall to the skin line in the same row is minimized. Further, the position can be similarly adjusted using the boundary 665 between the pectoral muscle region 663 and the breast region 664. Such alignment means facilitates a comparative interpretation by a doctor, and a more accurate diagnosis can be expected.

  In addition, there is a photographing direction discriminating means for automatically discriminating the photographing direction of the MLO image and the CC image by analyzing or identifying the image data, and the left breast and the right breast are automatically analyzed by analyzing or identifying the image data. It has left and right breast discriminating means for discriminating, and it is not necessary for the user to perform grouping as necessary, and appropriate grouping is easily performed, so that quick and accurate diagnosis can be performed.

  Further, it has an abnormal shadow candidate detection unit 606 for detecting an abnormal shadow candidate of an image, and stores information detected by the abnormal shadow candidate detection unit 606 in the abnormal shadow storage unit 607. In this way, the abnormal shadow candidate of the image is detected, and the abnormal shadow candidate is displayed. As shown in FIGS. 21 to 23, the abnormal shadow candidate is displayed by adding a mark to the abnormal shadow candidate position of the image. FIG. 21 is an example in which a mark is added to an abnormal shadow candidate position for mass detection of a mass shadow, FIG. 22 is an example in which a mark is added to an abnormal shadow candidate position for calc detection of microcalcification, and FIG. This is an example in which a mark is attached to an abnormal shadow candidate position for detection of computerization, and since the mark is added to the abnormal shadow candidate position of such an image and displayed, simple and reliable abnormal shadow can be easily recognized. In addition, rapid and accurate image diagnosis can be performed. The shape of the mark is not limited to that shown in FIGS. 21 to 23, and may be an arrow, for example. It is desirable to change the shape and color according to the type of abnormal shadow.

  Further, as shown in FIG. 24, a scale scale 670 can be added to the image. By adding the scale graduation 670 to the image, for example, the size of an abnormal shadow or the like can be easily recognized by the scale graduation.

  Furthermore, as shown in FIG. 25, white portions 671, omissions 672, and the like are generated in the image by a shielding material such as a lead plate at the time of photographing. The occluded part is displayed in black. In this way, the lead shielding portion of the image is displayed in black, so that the lead shielding portion of the image is not misunderstood as an abnormal shadow or the like, and an effect of reducing eye fatigue can be expected, which is useful for improving the interpretation performance.

  In addition, as shown in FIG. 26, different image processing is performed on the inner area and the outer area of the enlarged display window 681 so that, for example, the abnormal shadow of the enlarged display window 681 can be conspicuous, and the abnormal shadow can be detected. It can be done more easily, accurately and quickly.

  This image processing includes gradation processing, frequency enhancement processing, dynamic range compression processing, and interpolation processing, which have been described in detail above.

  For example, different gradation processing is performed on the inner area and the outer area of the enlarged display window 681. Specifically, a gradation processing lookup table corresponding to different gradation conversion curves is stored in advance for the inner area and the outer area of the enlarged display window 681, and each gradation process is performed at the time of display. Processing data obtained by referring to the lookup table is displayed. At this time, it is preferable that the contrast of the gradation conversion curve corresponding to the inner area of the enlarged display window is higher than the contrast of the gradation conversion curve corresponding to the outer area.

  In addition, instead of predetermining the gradation conversion curve corresponding to the area inside the enlarged display window, the image data in the enlarged display window is statistically analyzed when the enlarged display window is determined, and the result is A gradation conversion curve may be created based on this. Specifically, the contrast of the gradation conversion curve is determined so that the substantially maximum value and the substantially minimum value of the image data in the enlarged display window are displayed with a predetermined luminance, and the image data in the enlarged display window is accumulated. Obtain a signal value that makes the histogram value a predetermined value and create a gradation conversion curve so that the signal value is displayed with a predetermined luminance, or calculate a histogram of the image data in the enlarged display window A gradation conversion curve based on a known histogram equalization technique is created.

  Further, only the area inside the enlarged display window may be displayed with gradations reversed in black and white.

  As another example, different frequency emphasis processing is performed on the inner area and the outer area of the enlarged display window 681. For example, when a non-sharp mask processing method is used as the frequency enhancement process, different mask sizes and enhancement relationships are stored in advance for the inner area and the outer area of the enlarged display window, and each display is displayed. Processing data calculated using the mask size and the enhancement coefficient is displayed. When the multi-resolution method is used as the frequency treatment, different emphasis frequency adjustment bands and emphasis coefficients are stored in advance for the inner area and the outer area of the enlargement display window, and each emphasis frequency is displayed at the time of display. The processing data calculated using the band and the emphasis coefficient is displayed. At that time, it is preferable that the enhancement coefficient corresponding to the inner area of the enlarged display window is larger than the enhancement coefficient corresponding to the outer area. Further, it is preferable that the frequency emphasis processing condition is determined so that the main emphasis frequency corresponding to the inner region of the enlarged display window is higher than the main emphasis frequency corresponding to the outer region.

  As another example, different dynamic range compression processing is performed on the inner area and the outer area of the enlarged display window 681. For example, the dynamic range compression process is applied only to the area outside the enlarged display window, and the dynamic range compression process is not applied to the inner area.

  Furthermore, regarding the interpolation processing, when the image data is displayed on the image display means 8, if the matrix size of the image data is different from the matrix size of the display area, the interpolation processing is necessary. As the interpolation processing, a known interpolation calculation method such as nearest neighbor interpolation, linear interpolation, spline interpolation, cubic convolution interpolation, bell spline interpolation, or the like can be used (IEEE Trans on Acoustics and Signal Processing, vol. ASSP =). 29, no. 6, 1981. IEEE Trans, on Medical Imaging, vol. M1-2, no3, 1983, SPIE proc, M1-11, 1988). The order of the interpolation function used for the interpolation calculation is, for example, 0th order for nearest neighbor interpolation, 1st order for linear interpolation, 3rd order for spline interpolation, cubic convolution interpolation, bell spline interpolation, etc. As the function is used, it is possible to reduce the deterioration of the image information accompanying the interpolation process.

  As described above, the image processing can be performed easily, accurately, and quickly by detecting an abnormal shadow by performing image processing such as gradation processing, frequency enhancement processing, dynamic range compression processing, and interpolation processing.

  Further, the image processing condition is determined based on the enlargement ratio. In general, even with the same image, the smaller the enlargement ratio, the higher the contrast visually. Therefore, increasing the enlargement ratio increases the contrast, increasing the enlargement ratio increases the degree of enhancement of the frequency enhancement process, and increasing the enlargement ratio increases the order of the interpolation function of the interpolation process. Since the image processing conditions are determined based on the enlargement ratio in this way, the detection of abnormal shadows can be performed easily, accurately, and quickly with little image disturbance and information deterioration due to enlargement.

  The image processing condition is determined based on the type of abnormality. As described above, since the image processing condition is determined based on the type of abnormality, the abnormal shadow can be detected easily, accurately, and quickly according to the type of abnormality.

  Specifically, since the microcalcification has a lower object contrast than the tumor cancer shadow, the contrast of the gradation conversion curve corresponding to the microcalcification is made higher than the contrast of the gradation conversion curve corresponding to the tumor cancer shadow. . In addition, since the microcalcification includes a higher frequency structure than the tumor cancer shadow, the enhancement coefficient of the frequency enhancement processing corresponding to the microcalcification is made larger than the enhancement coefficient corresponding to the tumor cancer shadow, The main enhancement frequency of the corresponding frequency enhancement processing is set higher than the main enhancement frequency corresponding to the tumor cancer shadow.

  Further, the size of the enlarged display window 681 is determined based on the size of the abnormal shadow candidate, and as this example, the size is set so that the entire tumor can be displayed, and all of the micro calcification shadows included in the micro calcification cluster are set. Set to a size that can be displayed. Thus, since the size of the enlarged display window 681 is determined based on the size of the abnormal shadow candidate, the abnormal shadow becomes easier to see.

  Further, the enlargement ratio of the image is determined on the basis of the pixel size of the image and the resolution of the image display means 608, whereby the image is not distorted due to the enlargement of the image and the abnormal shadow becomes easier to see.

  Also, it is determined to be an integer multiple of the actual size. For example, the enlargement ratio with respect to the actual size can be determined by monitor size / (monitor resolution × pixel size of input image). By deciding to be an integral multiple of the actual size in this way, since the image is the actual size in the diagnosis by the conventional film, the actual size or the size of the integral multiple is easy to understand intuitively for the diagnostician.

  Further, when the information about the enlargement ratio of the image is displayed together with the image, it is easy to determine the part of the abnormal shadow, the size, etc., and the abnormal shadow can be detected easily, accurately, and quickly.

  For example, the enlargement ratio is displayed numerically in an area other than the image display area of the monitor. Alternatively, it is displayed numerically on the edge of the display image. The enlargement ratio may indicate both an outer enlargement ratio and an inner enlargement ratio of the enlargement display window. Also, when the pointer indicates the outside of the enlargement display window, the enlargement ratio outside the enlargement display window is displayed, and when the inside indicates, the display is switched to display the enlargement ratio inside the enlargement display window. May be.

  As another example, the enlargement factor inside the enlargement display window is displayed numerically adjacent to the enlargement display window 681. Alternatively, the image is displayed so as to overlap the edge of the enlarged display window 681 or a frame surrounding the enlarged display window 681. Further, in addition to the numerical value indicating the enlargement factor, it may be indicated by an icon such as a figure whose size is changed according to the enlargement factor.

  Also, using the pixel size of the image and the resolution of the image display means 608, it is converted into an enlargement ratio with respect to the actual size and displayed. In this way, since it is converted and displayed based on the actual size, the size is easy to understand intuitively for the diagnostician.

  Further, enlargement display control for changing any of the position of the enlargement display window 681, the size of the enlargement display window 681, the enlargement ratio of the image in the enlargement display window 681, and the image processing conditions of the image in the enlargement display window 681. It has a signal input means.

  This enlarged display control signal input means is constituted by an image output signal input means 603. Further, as an enlarged display control signal input means, for example, a mouse, a keyboard, a touch panel, or the like is used. For example, the position of the enlarged display window is scrolled in synchronization with the movement of the mouse. Alternatively, the enlargement ratio in the enlargement display window is continuously changed in synchronization with the movement of the mouse. Alternatively, the gradation processing conditions are continuously changed in synchronization with the movement of the mouse. Specifically, the gradation processing conditions can be freely and easily adjusted by changing the average luminance in synchronization with the left-right movement of the mouse and changing the contrast in synchronization with the vertical movement of the mouse. Alternatively, the frequency enhancement processing conditions are continuously changed in synchronization with the movement of the mouse. Specifically, by changing the mask size of the unsharp mask process in synchronization with the left and right movement of the mouse, and changing the enhancement coefficient of the unsharp mask process in synchronization with the vertical movement of the mouse, the frequency enhancement processing condition is set. It can be adjusted freely and easily.

  The change in the enlarged display state does not need to be continuous, and may be configured to change stepwise as the mouse button is clicked. It is also possible to adopt a configuration in which the gray scale is inverted by the click of the mouse button. Also, after various enlarged display conditions are changed by the image output control signal input means 603 which is an enlarged display control signal input means, a “determined” signal is sent to associate the final enlarged display conditions with the image data. And may be stored in the image storage means 605.

  As described above, any of the position of the enlarged display window 681, the size of the enlarged display window 681, the enlargement ratio of the image in the enlarged display window 681, and the image processing conditions of the image in the enlarged display window 681 depending on the state of the abnormal shadow or the like. By changing this, the abnormal shadow can be seen more easily, and the abnormal shadow can be detected easily, accurately, and quickly.

  In addition, a mark is added to the abnormal shadow candidate position for display. As an example of adding this mark, for example, a mark is added to an abnormal shadow candidate other than the abnormal shadow candidate for which the enlarged display window 681 is set. Next to the currently set enlarged display window, a mark is added to the abnormal shadow candidate for which the enlarged display window 681 is to be set. In addition, a mark having a different shape is added for each type of abnormality or each certainty of abnormality. A different color mark is added for each type of abnormality or certainty of abnormality. A mark having a different size is added for each type of abnormality or for each certainty of abnormality. For example, an abnormal shadow candidate to which the enlarged display window has already been applied and an abnormal shadow candidate to which the enlarged display window has not been applied are added with different color marks. In this way, since the mark is added to the abnormal shadow candidate position and displayed, the abnormal shadow can be found more easily by the mark, and the abnormal shadow can be detected easily, accurately, and quickly.

  In FIG. 26, the mark is displayed as an arrow mark in the vicinity that does not overlap with the abnormal shadow candidate. However, the mark is not limited to this, and is displayed as a closed curve mark surrounding the abnormal shadow candidate as shown in FIGS. May be. Further, for example, the display and non-display of the mark may be switched by selecting using a button mouse set on the screen.

  The image displayed on the image display unit 608 can be printed on a film or paper by the image printing unit 609 as it is or after being edited.

  The image storage unit 605 of the PCI image diagnosis support apparatus according to this embodiment stores PCI radiation image data. The abnormal shadow candidate detecting means 606 detects abnormal shadow candidates by analyzing the PCI radiographic image data, and the PCI radiographic image is clearer than a normal image, so that the abnormal shadow can be found with higher accuracy. . The image display means 608 displays the stored PCI radiation image data and detected abnormal shadow candidates.

  Next, still another embodiment of the PCI image diagnosis support apparatus will be described.

  As shown in FIG. 27, the PCI image diagnosis support apparatus of this embodiment is configured in the same manner as the embodiment shown in FIGS. 16 to 26, but the image processing means 604 is larger than the subtraction processing means 604a. And an alignment processing means 604c. The subtraction processing unit 604a and the size alignment processing unit 604c are configured in the same manner as the subtraction processing unit 150a and the size alignment processing unit 150c of the embodiment shown in FIG.

  Since the PCI radiographic image is particularly excellent in the ability to depict blood vessels or the like, for example, a lesion or the like can be extracted based on a difference from a normal captured image. As a result, the accuracy of diagnosis support is improved.

  Next, still another embodiment of the PCI image diagnosis support apparatus will be described.

  As shown in FIG. 28, the PCI image diagnosis support apparatus of this embodiment is configured similarly to the embodiment shown in FIGS. 16 to 26. However, the image processing means 604 is larger than the addition processing means 604b. And an alignment processing means 604c. The addition processing unit 604b and the size alignment processing unit 604c are configured in the same manner as the subtraction processing unit 150B and the size alignment processing unit 150c of the embodiment shown in FIG. With this form, it is possible to obtain an image having high sharpness and further adding images to obtain an image with little noise component and good graininess. As a result, the accuracy of diagnosis support is improved.

Furthermore, the PCI image diagnosis support apparatus may include the above-described subtraction processing unit 604a and addition processing unit 604b, and diagnosis support with higher accuracy is possible.
Further, the present invention is not limited to the medical field, and can be applied, for example, to the field of industrial nondestructive inspection.

  The present invention can be applied to a radiographic image processing apparatus used in the medical field using radiation, can appropriately perform radiographic image processing, and can improve the image quality of energy subtraction.

It is a figure which shows the structure of a PCI radiographic image processing apparatus. It is a schematic block diagram of a mammography apparatus. It is a figure which shows the structure of an image processing circuit. It is a figure for demonstrating irradiation field recognition processing. It is a figure which shows the extraction method of a signal area | region. It is a figure which shows a gradation conversion characteristic. It is a figure which shows the relationship between an emphasis coefficient and image data. It is a figure which shows the relationship between an emphasis coefficient and image data. It is a figure for demonstrating a dynamic range compression process. It is a figure which shows the structure of other embodiment of a PCI radiographic image processing apparatus. It is a figure which shows the structure of other embodiment of a radiographic image reader. It is a figure explaining template matching. It is a figure explaining the alignment by performing two linear movement and rotational movement of two X-ray images so that two marks may overlap. It is a figure which shows the structure of other embodiment of a PCI radiographic image processing apparatus. It is a figure which shows the structure of other embodiment of a PCI radiographic image processing apparatus. It is a schematic block diagram of an image diagnosis assistance apparatus. It is a figure which shows the detection of a microcalcification cluster and a mass shadow. It is a figure which shows the switching display of an image. It is a figure explaining operation of a display. It is a figure which arrange | positions and displays the image of the left breast of the same patient and the same imaging | photography direction, and the image of the right breast arranged side by side so that a nipple may face outward. It is a figure which shows the example which attached | subjected the mark to the abnormal shadow candidate position of the mass detection of a mass shadow. It is a figure which shows the example which attached | subjected the mark to the abnormal shadow candidate position of calc detection of microcalcification. It is a figure which shows the example which attached | subjected the mark to the abnormal shadow candidate position of the clutter detection of micro calcification. It is the figure which added the scale mark to the image. It is a figure which shows the state in which a white part, an omission, etc. arise with a lead plate at the time of imaging | photography. It is a figure which shows switching to the screen without an enlarged display window, the screen which expands and shows the rank 1 of an abnormal shadow candidate, and the screen which expands the rank 2 with an abnormal shadow candidate. It is a schematic block diagram of other embodiment of an image diagnosis assistance apparatus. It is a schematic block diagram of other embodiment of an image diagnosis assistance apparatus.

Explanation of symbols

5 Subject 10 Control unit 11 CPU
12 image processing circuit 27 input means 30 radiation source 40 radiation image reader 41 imaging panel 60 output means 61 interpolation processing condition storage means 62 imaging information storage means 63 image processing means 100 image processing means 105 radiation 106 subject 110 PCI image processing means 120 Normal imaging image processing means 130 Radiation generation source 140 Radiation image reader 150 Control unit 150a Subtraction processing means 150b Addition processing means 150c Size alignment processing means 152 Imaging information storage means 200 Radiation image detection means 300 Imaging information storage means 602 Image Data input means 603 Image output control signal input means 604 Image processing means 604a Subtraction processing means 604b Addition processing means 604c Size alignment processing means 605 Image storage means 606 Abnormal shadow candidate detection means 607 Abnormal shadow憶 608 image display unit 609 the image printing means 610 an image output control means 652 imaging information storage means

Claims (5)

It has a X-ray tube focus size D ([mu] m) is 30 to 1,000, and X-ray detector for detecting X-ray image transmitted through the Utsushitai,
The distance R 1 (m) from the X-ray tube before Symbol the Utsushitai, R 1 ≧ (D (μm ) - 7) in a range of / 200, the distance from the object to the X-ray detector R2 the (m), means for imaging as well as imaging the first radiographic image and the R2 ≧ 0.15, the second radiation image is brought into close contact with the object to the X-ray detector,
Processing means for performing a first radiographic image, the size adjustment before Symbol second radiation image,
A radiographic image processing apparatus comprising means for creating a difference image between the first radiographic image and the second radiographic image that have been subjected to size matching.   The radiographic image processing apparatus according to claim 1, wherein the first radiographic image and the second radiographic image are captured by one X-ray irradiation. A first X-ray detector for imaging the pre-Symbol first radiation image,
A second X-ray detector for capturing the second radiation image;
The radiation image processing apparatus according to claim 2, further comprising a filter containing a low energy component absorbing substance of radiation between the first X-ray detector and the second X-ray detector. Having photographing information storage means for storing management information relating to photographing, including an enlargement ratio;
Before Kisho management means, on the basis of the enlargement rate included in the management information on imaging combined magnitude of the second radiation image with the first radiographic image, and performing subsequent positioning process The radiation image processing apparatus of any one of Claim 1 thru | or 3 . Before Kisho management means, the determined enlargement ratio first radiographic image and based on the analysis result of the second radiation image, on the basis of the enlargement ratio obtained first radiation image and the second The radiographic image processing apparatus according to any one of claims 1 to 3 , wherein the size of the radiographic image is adjusted, and then alignment processing is performed.