JP2012228407A - X-ray radiographing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray radiographing apparatus which corrects the gradation of chest X-ray images so that a lung field region obtains sufficiently stable luminance and contrast regardless of a subject.SOLUTION: The lung field region, an intra-diaphragm region, and a near-pyramid lung field region of the chest X-ray images are each extracted, feature quantities of pixel values of the respective regions are extracted, a gradation conversion table is prepared on the basis of the extracted feature quantities, and the gradation conversion of the chest X-ray images is performed using the gradation conversion table.

Description

  The present invention relates to a tone correction technique for a chest X-ray image taken by an X-ray imaging apparatus.

  In general, an X-ray imaging apparatus detects X-rays transmitted through a subject with an X-ray detector, performs desired image processing using the detected image data, and displays an X-ray image on an image display apparatus. At this time, the image processing is performed so as to obtain appropriate brightness and contrast according to the imaging region.

  Patent Document 1 describes an image for searching for a thoracic vertebra region on the diaphragm side and correcting the gradation so that an image feature amount of the searched thoracic vertebra region becomes a predetermined target value when correcting the tone of the chest X-ray image. A processing apparatus is disclosed.

Japanese Unexamined Patent Publication No. 2007-300966

  However, in Patent Document 1, since the tone correction of the chest X-ray image is performed using only the image feature amount of the thoracic vertebra region on the diaphragm side, a sufficiently stable luminance regardless of the subject, particularly for the lung field region, And it was difficult to acquire chest X-ray images with contrast.

  Therefore, an object of the present invention is to provide an X-ray imaging apparatus capable of performing gradation correction of a chest X-ray image so that a lung field region has sufficiently stable luminance and contrast regardless of a subject. That is.

  In order to solve the above-described problems, the present invention is configured as follows. An X-ray irradiation unit that irradiates X-rays, an X-ray detection unit that detects X-rays emitted from the X-ray irradiation unit and converts them into electrical signals, and an X-ray signal output from the X-ray detection unit An X-ray imaging apparatus having an X-ray image processing unit for converting into a X-ray image and a display unit for displaying an X-ray image, wherein the X-ray image processing unit extracts a lung field region of a chest X-ray image Field region extraction processing unit, intra-diaphragm vertebral body region extraction processing unit for extracting the vertebral body vertebral body region, vertebral body vicinity lung field region for extracting the vertebral body nearby lung field region, and pixels of each extracted region A region feature amount extraction processing unit that extracts a feature amount of a value, a tone conversion table creation processing unit that creates a tone conversion table used for tone conversion of a chest X-ray image based on the feature amount, and tone conversion A gradation conversion processing unit that performs gradation conversion of the chest X-ray image based on the table.

  According to the present invention, it is possible to provide an X-ray imaging apparatus capable of performing gradation correction of a chest X-ray image so that a lung field region has sufficiently stable luminance and contrast regardless of a subject. it can.

The figure which shows schematic structure of the X-ray imaging apparatus of this invention Functional block diagram for explaining the X-ray image processing unit of the present invention The flowchart figure for demonstrating the operation | movement order of the X-ray image processing part of this invention The flowchart figure for demonstrating the trunk area | region extraction process part of this invention (a)-(d) The figure which shows the chest X-ray image for demonstrating the trunk area | region extraction process part of this invention The figure which shows the profile of the chest X-ray image and chest X-ray image for demonstrating the trunk area | region extraction process part of this invention The figure which shows the profile of the trunk X-ray image and trunk X-ray image for demonstrating the vertebral body area | region extraction process of this invention The flowchart figure for demonstrating the lung field area | region extraction process of this invention The figure which shows the profile of trunk X-ray image and trunk X-ray image for demonstrating the lung field area | region extraction process of this invention The flowchart figure for demonstrating the vertebral body area | region extraction process in the diaphragm of this invention The figure which shows the profile of the lung field area | region X-ray image and lung field area | region X-ray image for demonstrating the vertebral body area | region extraction process in the diaphragm of this invention The flowchart figure for demonstrating the thoracic spine vicinity lung field area | region extraction process of this invention The figure which shows the profile of the chest X-ray image and chest X-ray image for demonstrating the thoracic spine vicinity lung field area | region extraction process of this invention Outline diagram for explaining gradation conversion table creation processing of the present invention Functional block diagram for explaining the image processing unit for adjustment of the present invention Outline diagram for explaining gradation conversion table adjustment of the present invention

  Hereinafter, the X-ray imaging apparatus of the present invention will be described in detail with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the invention, and the repetitive description thereof is omitted.

FIG. 1 is a schematic diagram showing a configuration example of an embodiment of the X-ray imaging apparatus of the present invention.
The X-ray imaging apparatus of the present invention is opposite to the X-ray irradiation unit 101 that irradiates the subject 100 with X-rays, the X-ray diaphragm device 102 that sets the X-ray irradiation region for the subject 101, and the X-ray irradiation unit 101 An X-ray detector 103 that detects X-rays transmitted through the subject 100 and converts them into electrical signals, and X-rays that perform image processing on the X-ray signals output from the X-ray detector 103 An image processing unit 104, an X-ray image storage unit 105 that stores an X-ray image processed by the X-ray image processing unit 104, a display unit 106 that displays an X-ray image, and a control that controls each of the above components A unit 107 and an operation unit 108 for giving a command to the control unit 106.

  The X-ray irradiation unit 101 includes an X-ray tube that generates X-rays and a high voltage generation unit that supplies electric power to the X-ray tube. Further, the X-ray irradiation unit 101 may include an X-ray filter that selectively transmits X-rays having specific energy.

  The X-ray diaphragm device 102 has a plurality of X-ray shielding lead plates that shield X-rays generated from the X-ray irradiation unit 101, and moves each of the plurality of X-ray shielding lead plates to the subject 100. Determine the X-ray irradiation area.

  The X-ray detector 103 is configured by, for example, a plurality of detection elements that detect X-rays arranged in a two-dimensional array, and is irradiated from the X-ray irradiation unit 101 and transmitted through the subject 100. It is a device that detects X-ray signals according to the incident dose.

  The X-ray image processing unit 104 performs image processing on the X-ray signal output from the X-ray detector 103, and outputs an image-processed X-ray image. Image processing includes gamma conversion, gradation conversion processing, image enlargement / reduction, and the like.

  The display unit 106 displays the X-ray image output from the X-ray image processing unit 104 or the X-ray image stored in the X-ray image storage unit 105.

Next, Example 1 of the present invention will be described with reference to FIGS.
The X-ray image processing unit 104 shown in FIG. 1 will be described in detail with reference to FIG. FIG. 2 is a functional block diagram for explaining the X-ray image processing unit 104 of the present invention.

  The X-ray image processing unit 104 of the X-ray imaging apparatus of the present invention performs logarithmic conversion in order to convert a chest X-ray signal transmitted through the chest of the subject 100 acquired by the X-ray detector 103 into an X-ray attenuation characteristic. An X-ray image conversion creation unit 201 that performs processing and creates a chest X-ray image; a trunk region extraction processing unit 202 that extracts a trunk region from the chest X-ray image created by the X-ray image conversion creation unit 201; A vertebral body region extraction processing unit 203 that extracts a vertebral body region from the trunk region extracted by the trunk region extraction processing unit 202, a lung field region extraction processing unit 204 that extracts a lung field region, and a vertebral body region extraction An intra-diaphragm vertebral body region extraction processing unit 205 that extracts a vertebral body region overlapping the diaphragm from the vertebral body region and lung field region extracted by the processing unit 203 and the lung field region extraction processing unit 204. And in the lung field region, the vertebral body region adjacent to the vertebral body region Vertebral body region 206, pulmonary region extraction processing unit 204, intra-diaphragm vertebral body region extraction processing unit 205, and pulmonary region pulmonary region region 206, respectively. A region feature amount extraction processing unit 207 that extracts feature values of pixel values of each region of the inner vertebral body region and the lung field region near the vertebral body, and the respective feature amounts extracted by the region feature amount extraction processing unit 207 A tone conversion table creation processing unit 208 that creates a tone conversion table for tone conversion of the chest X-ray image, and the tone conversion table created by the tone conversion table creation processing unit 208 And a tone conversion processing unit 209 that performs tone conversion of the chest X-ray image based on the above.

  Further, the chest X-ray image subjected to gradation conversion by the gradation conversion processing unit 209 is displayed on the display unit 106. The chest X-ray image is stored in the X-ray image storage unit 105.

Next, the operation sequence of the X-ray image processing unit 104 will be described using the flowchart shown in FIG.
In step 301, the X-ray image conversion creation unit 201 performs a chest X-ray image creation process for creating a chest X-ray image using the chest X-ray signal acquired by the X-ray detector 103.

  In step 302, the trunk region extraction processing unit 202 performs a trunk region extraction process for extracting a trunk region from the chest X-ray image.

  In step 303, the trunk region extraction processing unit 202 performs vertebral body region extraction processing for extracting a vertebral body region from the chest X-ray image.

  In step 304, lung field region extraction processing unit 204 performs lung field region extraction processing for extracting a lung field region from the chest X-ray image.

  In step 305, an intra-diaphragm vertebral body region extraction process is performed by the intra-diaphragm vertebral body region extraction processing unit 205 to extract the intra-diaphragm vertebral body region from the vertebral body region and the lung field region.

  In step 306, the vertebral body vicinity lung field region 206 performs the vertebral body vicinity lung field region processing for extracting the vertebral body vicinity lung field region from the vertebral body region and the lung field region.

  In step 307, the region feature amount extraction processing unit 207 performs region feature amount extraction processing for extracting feature values of pixel values of the respective regions from the lung field region, intra-diaphragm vertebral body region, and vertebral body neighboring lung field region. It is.

  In step 308, the gradation conversion table creation processing unit 208 performs a gradation conversion table creation process for creating a gradation conversion table from the feature amount.

  In step 309, the gradation conversion processing unit 209 performs gradation conversion processing for performing gradation conversion of the chest X-ray image using the gradation conversion table.

  In step 310, the tone conversion processing unit 209 displays the tone-converted chest X-ray image on the display unit 106.

  Next, each processing unit following the trunk region extraction processing in the flowchart shown in FIG. 3 will be described in detail with reference to FIGS.

First, the trunk region extraction processing unit 202 will be described in detail with reference to FIGS.
The flowchart shown in FIG. 4 is a diagram showing an operation sequence of the trunk region extraction processing unit 202 of the present invention.

  The operation sequence will be described using the chest X-ray images shown in FIGS. 5 (a) to 5 (d) together with FIG. 4, and the chest X-ray images and the profiles of the chest X-ray images shown in FIG.

  In step 401, from the chest X-ray image 501 created by the X-ray image conversion creating unit 201, the X-ray shielding device 502 removes the X-ray shielding region 502 shielded from the X-rays generated from the X-ray irradiation unit 101 by the X-ray diaphragm device 102, Irradiation field extraction processing for extracting an X-ray irradiation field region 505 irradiated with X-rays to the X-ray detector 103 is performed. The irradiation field extraction processing detects the positions of the X-ray tube of the X-ray irradiation unit 101, the X-ray shielding lead plate of the X-ray diaphragm device 102, and the X-ray detector 103 using a sensor or the like. Then, geometric calculation is performed from the detection result, and the X-ray irradiation field region 505 is extracted. In addition, the irradiation field extraction processing sets a threshold value for the X-ray signal output from the X-ray detector 103 and binarizes it, and determines an X-ray shielding area 502 and an X-ray irradiation field area 505. Treatment methods and the like may be used.

  In step 402, direct ray removal processing is performed to remove the direct ray region 503 irradiated with X-rays directly on the X-ray detector 103 without passing through the subject 100 with respect to the X-ray irradiation field region 505. The direct ray removal process reaches the X-ray detector 103 based on the X-ray irradiation conditions generated from the X-ray irradiation unit 101 and the distance from the X-ray tube of the X-ray irradiation unit 101 to the X-ray detector 103. A threshold value of a detection value is obtained from the X-ray dose and the X-ray detection characteristics of the X-ray detector 103, and a direct line region 503 is distinguished from a portion that is not the direct line region 503. A chest X-ray image 506 is extracted from the image. Further, the chest X-ray image 506 may be subjected to histogram analysis of the X-ray irradiation field region 505 to obtain a threshold value for discriminating between the direct line region 503 and a portion that is not the direct line region 503.

  In step 403, a trunk X-ray image 507 from which the limbs 504 have been removed from the chest X-ray image 506 is extracted. When extracting the trunk X-ray image 507, as shown in FIG. 6, the vertical pixel values of the chest X-ray image 506 are integrated, and the profile 601 taken in the horizontal direction and the horizontal direction of the chest X-ray image 506 Are integrated to obtain a profile 602 taken in the vertical direction, and thresholds 603 and 604 are set for the profiles 601 and 602, respectively. The threshold values 603 and 604 may be the average values of the respective pixel values obtained from the profiles 601 and 602, or may be a fixed ratio with respect to the average value, for example, 1.1 times. good.

  An area having a maximum width that is greater than or equal to the threshold values 603 and 604 is extracted. Here, the width indicates the length in the horizontal direction in the profile 601, and the length in the vertical direction in the profile 602. As a result, a horizontal extraction region 605 and a vertical extraction region 506 are obtained from the profiles 601 and 602, respectively. From the horizontal extraction region 605 and the vertical extraction region 506, chest X-rays are obtained. A trunk X-ray image 507 obtained by removing the limbs 504 from the image 506 can be extracted.

Next, the vertebral body region extraction processing unit 203 will be described in detail with reference to FIG.
The profile of the trunk X-ray image and the trunk X-ray image shown in FIG. 7 is a diagram for explaining processing by the vertebral body region extraction processing unit 203 of the present invention.

  The vertebral body region extraction processing unit 203 of the present invention extracts a vertebral body X-ray image 701 obtained by extracting vertebral bodies from the trunk X-ray image 507 extracted by the trunk region extraction processing unit 202. When extracting the vertebral body X-ray image 701, as shown in FIG. 7, the vertical pixel values of the trunk X-ray image 507 are integrated, a profile 702 taken in the horizontal direction is acquired, and a threshold 703 is set. . The threshold value 703 is obtained from the minimum pixel value obtained from the profile 702.

  At this time, the threshold value 703 may be the minimum value itself, or a pixel value of a certain ratio to the minimum value, for example, 1.3 times may be used. An area having a threshold value 703 or less is extracted. Thereby, a lateral extraction region 704 is obtained from the profile 702, and a vertebral body X-ray image 701 obtained by extracting vertebral bodies from the trunk X-ray image 507 can be extracted from the lateral extraction region 704.

Next, the lung region extraction processing unit 204 will be described in detail with reference to FIG.
The flowchart shown in FIG. 8 is a diagram showing an operation sequence of the lung field region extraction processing unit 204 of the present invention. The operation sequence will be described using the trunk X-ray image and the profile of the trunk X-ray image shown in FIG. 9 together with FIG.

  In step 801, a lung field margin extraction process is performed for extracting a lung field margin from the trunk X-ray image 507 extracted by the trunk region extraction processing unit 202. The lung field region extraction processing unit 204 integrates the vertical pixel values of the trunk X-ray image 507 and acquires a profile 901 taken in the horizontal direction. When the pixel value is viewed from two directions of the profile 901 from the start point to the end point direction and from the end point to the start point direction, a position that becomes a valley first is derived. By extracting the two valleys, the lung field edge extraction process for extracting the edge of the lung field can be performed. Further, when the valley is derived, a smoothing process may be performed on the profile 901 so that a valley position can be easily derived after the smoothing process is performed.

  In step 802, lung field candidate region extraction processing is performed for extracting regions that are candidates for lung fields from the profile 902 in which only the inside of the two valleys is extracted. In the lung field candidate region extraction processing, a threshold value 903 is set for the profile 902. The region having the maximum width among the regions having the threshold value 903 or more is derived as profiles 904 and 905. At this time, there are two lung fields on the left and right in the profile 902. Therefore, when two regions with the same width are extracted, the two are derived as profiles 904 and 905. Derives the regions having the largest width and the next largest width as profiles 904 and 905, respectively.

In step 803, profile determination processing is performed on the profiles 904 and 905 to determine whether the profile is a lung field. Here, the profile determination process for the profile 904 will be described. In profile determination processing, a quadratic approximate expression 906 (Y = A (X−B) ² −C, Y is the pixel value, X is the position of the profile 904 in the horizontal direction, and A, B, and C are coefficients. If the coefficient A of the approximate expression 906 is less than zero and the extreme value of the quadratic expression is within the range of the profile 904, it is not the lung field when it is outside the range of the profile 904. Judge as area. The coefficient A being less than zero indicates a characteristic that the profile 904 is convex with respect to the larger pixel value. The determination processing of the profile 904 is completed, and the region determined as the lung field is extracted as the lung field region. The profile determination process for the profile 905 is the same as the process for the profile 904. A lung field region X-ray image 907 is extracted from the lung field region.

Next, the intradiaphragm vertebral body region extraction processing unit 205 will be described in detail with reference to FIG.
The flowchart shown in FIG. 10 is a diagram showing the operation sequence of the intra-diaphragm vertebral body region extraction processing unit 205 of the present invention. The operation sequence will be described using the lung field region X-ray image and the profile of the lung field region X-ray image shown in FIG. 11 together with FIG.

  In step 1001, the intraphrenic vertebral body region extraction processing unit 205 integrates the lateral pixel values of the lung field region X-ray image 907 from the lung field region X-ray image 907 extracted by the lung field region extraction processing unit 204. The profile 1101 taken in the vertical direction is acquired.

  In step 1002, a lower lung field position is derived using the profile 1101. In the derivation, a threshold value 1102 is set for the profile 1101. In the profile 1101, two points that become the threshold value 1102 are extracted, and an intersection C corresponding to the lower side of the lung field X-ray image 907 is derived from the two points.

  In step 1003, intra-diaphragm vertebral body region extraction processing is performed for extracting the intra-diaphragm vertebral body region that overlaps the diaphragm from the vertebral body X-ray image 701 extracted by the vertebral body region extraction processing unit 203 using the intersection point C. . The positional relationship between the intersection C and the vertebral body X-ray image 701 is associated, and a vertebral body region corresponding to the lower side of the intersection C is extracted. Thereby, an intra-diaphragm vertebral body region X-ray image 1103 obtained by extracting the intra-diaphragm vertebral body region is extracted.

Next, the vertebral body vicinity lung field region 206 will be described in detail with reference to FIG.
The flowchart shown in FIG. 12 is a diagram showing the operation sequence of the near-vertebral body lung field region 206 of the present invention. The operation sequence will be described using the lung field X-ray image and the profile of the lung field X-ray image shown in FIG. 13 together with FIG.

  In step 1201, the vertebral body vicinity lung field region 206 from the lung field region X-ray image 907 extracted by the lung field region extraction processing unit 204 accumulates the vertical pixel values of the lung field region X-ray image 907, A profile 1301 taken in the horizontal direction is acquired.

  In step 1202, a center position with respect to the lateral width of the vertebral body is derived from the vertebral body X-ray image 701 extracted by the vertebral body region extraction processing unit 203, and outward in the left and right directions from the position D of the profile 1301 corresponding to the center position. On the other hand, a location where the pixel value has the maximum deviation is derived, and a region 1302 inside the location is extracted.

  In step 1203, a region corresponding to the region 1302 is extracted from the lung field region X-ray image 907. The extracted region is a vertebral body vicinity lung field region, and a vertebral body vicinity lung field region X-ray image 1303 is extracted.

Next, the region feature amount extraction processing unit 207 will be described.
The region feature amount extraction processing unit 207 includes a lung field region extracted by the lung field region extraction processing unit 204, an intra-diaphragm vertebral body region extraction unit 205, and an adjacent vertebral body lung Feature values are extracted from the three regions of the lung field region near the vertebral body extracted by the field region unit 206, respectively. From the lung field region, the maximum pixel value in the lung field region is extracted as a feature amount. From the intra-diaphragm vertebral body region, the minimum pixel value in the intra-diaphragm vertebral body region is extracted as a feature amount. From the lung field near the vertebral body, a value that is an average value of the pixel values in the lung field near the vertebral body is extracted as a feature amount. In general, the lung field, the intra-diaphragm vertebral body region, and the lung field near the vertebral body have the highest X-ray transmittance. It becomes the order of the body area. Therefore, since gradation conversion is performed by the gradation conversion table creation processing unit 208 and the gradation conversion processing unit 209, which will be described later, so that favorable pixel values are obtained in the three regions, in each region as described above. The pixel values having different characteristics, that is, the maximum value, the minimum value, and the average value of the pixel values are used as feature amounts in the respective regions.

Next, the gradation conversion table creation processing unit 208 will be described with reference to FIG.
The tone conversion table creation processing unit 208 creates a tone conversion table using the feature values of each region obtained by the region feature value extraction processing unit 207.

  As shown in FIG. 14, the gradation conversion table creation processing unit 208 takes an input pixel value on the horizontal axis and an output pixel value on the vertical axis, and displays the feature quantity as an input pixel value and corresponding to the feature quantity. The target output pixel values a to c when outputting to the unit 106 etc. are plotted as output pixel values for each feature amount, and in addition to the plot, the input pixel value and the output pixel value are the maximum value and the minimum value, respectively. The start point X and the end point Y taken are plotted, and a gradation conversion table is created using the lines for interpolating the plots. For the target output pixel values a to c, fixed values set in advance are used. Further, interpolation of the target output pixel values a to c and the start point X and end point Y may be performed by B-spline, linear interpolation, or the like, or an approximate expression may be used.

  Next, the gradation conversion processing unit 209 will be described. The gradation conversion processing unit 209 performs gradation conversion processing on the chest X-ray image created by the X-ray image conversion creation unit 201 using the gradation conversion table created by the gradation conversion table creation processing unit 208. Then, the chest X-ray image subjected to the gradation conversion processing is displayed on the display unit 106 or stored in the X-ray image storage unit 105.

  As described above, according to the X-ray imaging apparatus of the present invention, since the main blood vessels are stretched in the chest, three regions in which pixel values vary depending on the subject or the like, a lung field region, a vertebral body region in the diaphragm, And a lung field region near the vertebral body, and gradation conversion processing of the chest X-ray image using the feature amount corresponding to each region, sufficiently stable brightness and contrast regardless of the subject Thus, the tone correction of the chest X-ray image can be performed.

  Next, Example 2 of the present invention will be described with reference to FIG. Further, differences from the first embodiment will be described.

  The X-ray image processing unit 104 of the X-ray imaging apparatus according to the present exemplary embodiment includes an X-ray image gradation adjustment processing unit 1601 in addition to the processing units and the creation units illustrated in the first exemplary embodiment. The X-ray image gradation adjustment processing unit 1601 allows the operator to adjust the gradation conversion table created by the gradation conversion table creation processing unit 208 using the operation unit. The tone conversion table created by the tone conversion table creation processing unit 208 is displayed on the display unit 106 by the X-ray image tone adjustment processing unit 1601. The displayed gradation conversion table has a user adjustment unit 1701 that allows the operator to adjust the gradation conversion table using the operation unit.

  When the intra-diaphragm vertebral body region feature amount is T1, the vertebral body vicinity lung field region feature amount is T2, and the lung field region feature amount is T3, the size of the input pixel value of the feature amount is T1 <T2 <T3. The user adjustment unit 1701 corresponds to the input pixel value T2 indicating the middle size of the three input pixel values, and the operator can arbitrarily adjust the target output pixel value b of T2 using the operation unit. A slider S1 is provided. By sliding the slider S1 up and down, the target output pixel value b of T2 can be arbitrarily adjusted. At this time, the target output pixel value a of T1 and the target output pixel value c of T3 change in conjunction with the change of the target output pixel value b of T2.

  Further, the variation amount of the target output pixel value a of T1 varies while maintaining the difference ratio (A1 / A2) of the output pixel values of the start points X and T1, and T1 and T2. The same applies to T3, and the amount of change in the target output pixel value c of T3 varies while maintaining the difference ratio (B1 / B2) of the output pixel values of the end points Y and T3 and T3 and T2. The gradation conversion processing unit 209 performs gradation conversion processing on the chest X-ray image created by the X-ray image conversion creation unit 201 using the gradation conversion table adjusted by the X-ray image gradation adjustment processing unit 1601. The chest X-ray image subjected to the gradation conversion processing is displayed on the display unit 106 or stored in the X-ray image storage unit 105.

  As described above, according to the X-ray imaging apparatus of the present invention, with respect to the gradation conversion table created by the gradation conversion table creation processing unit 208, the target output of the vertebral body vicinity lung field region feature amount T2 on the gradation conversion table. The pixel value b can be adjusted arbitrarily by the operator, and in conjunction with the adjustment, the difference between the output pixel values of the start points X and T1, T1 and T2, the end points Y and T3, and T3 and T2 By changing T1 and T3 while maintaining the above, the chest X-ray image desired by the operator can be acquired while maintaining the chest X-ray image with sufficiently stable brightness and contrast regardless of the subject. be able to.

  100 subject, 101 X-ray irradiation unit, 102 X-ray diaphragm, 103 X-ray detector, 104 X-ray image processing unit, 105 X-ray image storage unit, 106 display unit, 107 control unit, 108 operation unit, 201 X Line image conversion creation unit, 202 trunk region extraction processing unit, 203 vertebral body region extraction processing unit, 204 lung field extraction processing unit, 205 intradiaphragmatic vertebral body region extraction processing unit, 206 vertebral body near lung field region, 207 Area feature extraction processing unit, 208 gradation conversion table creation processing unit, 209 gradation conversion processing unit, 501 chest X-ray image, 502 X-ray shielding area, 503 direct line area, 504 extremities, 505 X-ray irradiation field area, 506 Chest X-ray image, 507 Trunk X-ray image, 601, 602, 702, 901, 902, 904, 905, 1101, 1301 Profile, 603, 604, 703, 903, 1102 Threshold value, 605, 704 Area, 506 longitudinal extraction area, 701 vertebral body X-ray image, 906 approximation, 907 lung field X-ray image, 1302 inner area, 1303 vertebral body lung field area X Image, 1601 X-ray image tone adjustment processing section, 1701 the user adjusting unit

Claims (7)

X-ray irradiation unit for irradiating X-rays, X-ray detection unit for detecting X-rays irradiated from the X-ray irradiation unit and converting them into electrical signals, and X-ray signals output from the X-ray detection unit as X In an X-ray imaging apparatus having an X-ray image processing unit for converting into a line image and a display unit for displaying the X-ray image,
The X-ray image is a chest X-ray image, and the X-ray image processing unit includes a lung field region extraction processing unit that extracts a lung field region of the chest X-ray image, and a diaphragm that extracts a vertebral body region in the diaphragm. An inner vertebral body region extraction processing unit, a vertebral body vicinity lung field region that extracts a vertebral body vicinity lung field region, a region feature amount extraction processing unit that extracts a feature value of a pixel value of each of the extracted regions; A tone conversion table creation processing unit that creates a tone conversion table used for tone conversion of the chest X-ray image based on the feature amount, and a tone of the chest X-ray image based on the tone conversion table An X-ray imaging apparatus comprising: a gradation conversion processing unit that performs conversion.   The gradation conversion table creation processing unit outputs an input pixel value on one axis, an output pixel value on the other axis, and outputs a target output pixel value corresponding to the feature amount, using the feature amount as an input pixel value. Plotting each feature amount as a pixel value, plotting the start point and end point of the maximum value and minimum value of the input pixel value and output pixel value, respectively, and using the lines to interpolate each plot The X-ray imaging apparatus according to claim 1, wherein the gradation conversion table is created.   The feature value of the lung field region is a maximum value of pixel values in the lung field region, and the feature value of the intradiaphragm vertebral body region is a minimum value of pixel values in the intradiaphragm vertebral body region, 3. The X-ray imaging apparatus according to claim 1, wherein the feature quantity of the lung field near the body is an average value of pixel values in the lung field near the vertebral body.   The X-ray image processing unit includes an X-ray image gradation adjustment processing unit that allows an operator to adjust the gradation conversion table created by the gradation conversion table creation processing unit. The X-ray imaging apparatus as described in any one of thru | or 3.   The X-ray image gradation adjustment processing unit can adjust one of the three feature amounts so as to have an arbitrary target output image value, and in conjunction with the adjustment, the other two feature amounts The X-ray imaging apparatus according to claim 4, wherein the target output image value is varied.   The fluctuation of one target output image value of the other two feature amounts is the target output image value, the output image value of the start point, the target output image value, and the target output image value of the one feature amount. The difference ratio is maintained, and the variation of the other target output image value among the other two feature amounts is the target output image value, the output image value of the end point, the target output image value, and the one feature amount. The X-ray imaging apparatus according to claim 5, wherein a difference ratio from the target output image value is maintained.   The X-ray imaging apparatus according to claim 5, wherein the one feature amount is a feature amount of the lung field near the vertebral body.

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