JP2009136421A - Diagnostic x-ray apparatus and x-ray image processing method, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnostic X-ray apparatus and an X-ray image processing method which can quickly and accurately prepare a long image by setting a reference area in a first overlap area and a search area in a second overlap area. <P>SOLUTION: The diagnostic X-ray apparatus has a differentiation value computing section obtaining pixels having the absolute value of the differentiation value of a pixel value becomes maximum in the first overlap area, a reference area setting section setting a reference area of a predetermined size around the pixels, a search area setting section setting a search area in the second overlap area on the basis of the reference area, finding the same pattern as the pattern of the pixel value of the reference area from the search area, and obtaining the position of the pixel value of the reference area, and a long image preparation section pasting the first image and the second image together by relatively moving the position of the pattern of the pixel value of the reference area to the position of the pattern found by the search section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray diagnostic apparatus and an X-ray image processing method for creating a long image by combining images acquired by two X-ray imaging performed on a subject.

  Conventionally, in long imaging of the entire lower limb or the entire spine, X-ray imaging is performed, for example, twice along the lower limb or the spine, and a first image and a second image are created. The first image and the second image include an image of a common subject part. That is, the first image includes a first overlapping area that is an overlapping part of the second image, and the second image includes a second overlapping area that is an overlapping part of the first image.

  Conventionally, a parameter for alignment processing is provided on the basis of the density information of the first overlap area and the second overlap area, and the first overlap area and the second overlap area are pasted according to the parameters. A technique for creating a scale image has been proposed (for example, Patent Document 1).

  Conventionally, a plurality of candidate areas are uniformly set in the first overlapping area, and an area having a relatively large signal distribution is selected as an attention area from the plurality of candidate areas. On the other hand, an attention area larger than the attention area is set in the second overlapping area, and this area is set as a reference area. By translating and rotating the region of interest within the reference region, the translation and rotation conditions that are most similar to the region of interest are obtained, and the first overlap region and the second overlap region are pasted according to the conditions. A technique for creating a long image has been proposed (for example, Patent Document 2).

JP 2006-158701 A JP 2002-44413 A

  However, in the technique described in Patent Document 1, since the entire range of the first overlap region and the second overlap region is searched on the condition of the parameter based on the density information, a long time is required for the search. There was a problem that a scale image could not be created quickly.

  In the technique described in Patent Document 2, a plurality of candidate areas are uniformly set, and a region of interest is selected from the plurality of candidate areas. For example, the vicinity of the boundary between adjacent candidate areas If there is a region to be noted in this region, that region cannot be selected. Thereby, the creation accuracy of the long image is lowered, and a desired long image may not be obtained. In that case, since the long image is created again based on the reselected region of interest, there is a problem that the long image cannot be created quickly as a result.

  The present invention solves the above-described problem, and creates a long image quickly and with high accuracy by setting a reference region in the first overlap region and setting a search region in the second overlap region. An object of the present invention is to provide an X-ray diagnostic apparatus and an X-ray image processing method capable of performing the above.

In order to solve the above-described problem, the invention described in claim 1 is the imaging data acquired by the X-ray detector in each imaging in which at least one position of the X-ray detector or the X-ray tube is changed. An image creation unit for creating a first image and a second image before and after changing the position,
X-ray detection of a first overlapping region that is an overlapping portion with the second image in the first image and a second overlapping region that is an overlapping portion with the first image in the second image. An overlapping area calculation unit that calculates the position based on the position information of the X-ray tube and the X-ray tube; a differential value calculation unit that obtains a pixel having a maximum absolute value of the differential value of the pixel value in the first overlapping area; A reference area setting unit for setting a reference area having a predetermined size centered on a pixel having the maximum absolute value of the differential value of the pixel value;
A search area setting unit for setting a search area in the second overlapping area based on the reference area; and searching the search area for the same pattern as the pixel value pattern of the reference area, and the position of the searched pattern A long image in which the first image and the second image are pasted together by relatively moving the position of the pixel value pattern in the reference region to the position of the pattern searched by the search unit. An X-ray diagnostic apparatus comprising: a creation unit.

  According to the second aspect of the present invention, in each imaging in which the position of at least one of the X-ray detector or the X-ray tube is changed, the position is determined based on each imaging data acquired by the X-ray detector. An image creating unit that creates the first and second images before and after the change, a first overlapping region that is an overlapping portion of the first image and the second image, and the second image in the second image An overlapping area calculation unit that calculates a second overlapping area that is an overlapping part with the first image based on positional information of the X-ray detector and the X-ray tube; and a pixel value in the first overlapping area The first pixel that is the pixel having the maximum absolute value of the differential value is obtained, and the absolute value of the differential value of the pixel value next to the first image in the peripheral area of the predetermined size of the first pixel. A differential value calculation unit for obtaining a second pixel having a large value, the first pixel and the previous pixel A reference area setting unit for setting a reference area of a predetermined size including a second pixel; a search area setting unit for setting a search area in the second overlapping area based on the reference area; and the reference area A search unit for searching for the same pattern as the pixel value pattern in the search area, and determining a position of the searched pattern, and a position of the pixel value pattern in the reference area relative to the position of the pattern searched by the search unit An X-ray diagnostic apparatus comprising: a long image creating unit that pastes the first image and the second image by moving in a moving manner.

The invention according to claim 6 changes the position based on the imaging data acquired by the X-ray detector in each imaging in which the position of at least one of the X-ray detector or the X-ray tube is changed. Creating a first image and a second image before and after, a first overlapping region that is an overlapping portion with the second image in the first image, and the first image in the second image Calculating a second overlapping region that is an overlapping portion based on positional information of the X-ray detector and the X-ray tube, and obtaining a pixel having a minimum pixel value in the first overlapping region; A first pixel that is a pixel within the first overlapping region and having a maximum absolute value of a differential value of the pixel value in a peripheral region of a predetermined size of the pixel having the minimum pixel value. And obtaining a peripheral area of the predetermined size of the first pixel A step of obtaining a second pixel having a pixel value having a larger absolute value of a differential value next to the first pixel, and a reference area having a predetermined size including the first pixel and the second pixel. A step of setting a search area in the second overlapping area based on the reference area, and searching for a pattern identical to the pixel value pattern of the reference area from the search area Determining the position of
Pasting the first image and the second image by moving the position of the pixel value pattern of the reference region relative to the position of the pattern searched by the search unit. This is a characteristic X-ray image processing method.

  According to the first aspect of the present invention, since the reference area is provided around the pixel having the maximum absolute value of the differential value of the pixel value in the first overlapping area, the reference area is set in the first overlapping area. It can be assumed that the peripheral area of the most characteristic pixel is present, and it is presumed that the most characteristic pixel and its peripheral area exist in the area within the second overlapping area opposite to the reference area. Since the search area is provided in the opposite area, the pattern of pixel values can be searched quickly in the search area. Thereby, a long image can be created quickly.

  According to the second aspect of the present invention, the first pixel which is the pixel having the maximum absolute value of the differential value of the pixel value in the first overlapping region is obtained, and the first pixel in the peripheral region of the first pixel is obtained. Since the second pixel having the largest absolute value of the differential value of the pixel value after one image is obtained and the reference region is provided so as to include the first pixel and the second pixel, the pattern of the pixel value of the reference region The feature is increased, and the increased speed and accuracy when searching for the pattern of pixel values in the search area are increased.

  Further, according to the invention described in claim 6, since the first pixel and the second pixel are obtained in the peripheral region of the pixel having the minimum pixel value, and the reference region is provided so as to include the first pixel and the second pixel. For example, when creating a long image based on an image of a bone and its surroundings that tend to have a minimum pixel value, the characteristics of the pixel value pattern of the reference area further increase, and the pixel value The speed and accuracy when searching for the pattern in the operation area are further increased.

(Constitution)
The configuration of the X-ray image diagnostic apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the X-ray image diagnostic apparatus.

  The X-ray tube holding device 10 and the three-dimensional stand 20 are arranged at positions facing each other with the subject interposed therebetween. The X-ray tube holding device 10 includes an X-ray tube 11 and an X-ray restrictor 12. The solid stand 20 includes a grid 21 and an X-ray detector 22. The X-ray diaphragm 12 irradiates an appropriate position of the X-ray detector 22 with an X-ray beam for the purpose of optimizing the exposure dose. The X-ray diaphragm 12 forms an X-ray irradiation field on the X-ray detector 22. In addition, the grid 21 removes or reduces scattered radiation generated by the interaction between the subject and the X-ray in order to obtain a high-quality X-ray image.

  For example, the user sets items such as an exposure mode, a calibration mode, and a diagnosis by a display unit and an operation unit of a user interface (not shown). The system control means 1 receives these settings and sends the X-ray exposure conditions and timing according to the exposure mode to the X-ray control unit 31. The X-ray control unit 31 controls the voltage supplied from the high voltage generator 32 of the X-ray high voltage device 30 to the X-ray tube 11.

  Next, the configuration of the X-ray detector 22 will be described with reference to FIG. The X-ray sensor 221 is a sensor that constitutes a pixel, and is referred to as a pixel detection element or a pixel. The X-ray sensor 221 detects the X-rays by converting the charges into charges according to the intensity of the received X-rays and storing the charges. The X-ray sensor 221 includes, for example, a conversion element, a capacitive element that stores charges, and a semiconductor gate element (not shown) that extracts and outputs charges from the capacitive element.

  The X-ray sensors 221 are two-dimensionally arranged in the row direction and the column direction, and n sensor groups 220 are configured as a whole. In response to an instruction from the system control unit 1 or the readout control unit (not shown), the sensor column selection unit 230 instructs the array of sensor groups 220 to read pixel values for each column of the sensor group 220. The output is received by a variable amplifier (integral amplifier) 241 for each row and amplified. The output from the amplifier group 240 is output as digital data indicating a pixel value for each pixel (for each X-ray sensor 221) via the multiplexer 250 and the AD converter 260. This digital data corresponds to projection data.

  Further, offset and gain are corrected for the pixel value for each pixel, and the corrected projection data is sent to the input unit 41 of the image processing apparatus 40.

  The input unit 41 stores projection data for several frames in a high-speed memory (frame memory or frame buffer), and transfers the projection data to the storage device 42 according to an instruction from the control unit 43.

  The storage device 42 stores the projection data together with incidental information (patient name, imaging region, imaging direction, imaging conditions, etc.).

  The control unit 43 retrieves the program from the storage device 42, interprets the command, reads projection data from the storage device 42 based on the command, instructs the calculation unit 45 to process the projection data, and is processed by the calculation unit 45. The stored data is written into the storage device 42. In addition, the control unit 43 performs data input / output control with respect to the input unit 41, the display control unit 50, and the network output unit 51.

  Next, the configuration of the calculation unit 45 that processes the projection data will be described with reference to FIG. FIG. 3 is a block diagram illustrating a configuration of the calculation unit 45.

  The calculation unit 45 includes an image creation unit 451, an overlap region calculation unit 452, a differential value calculation unit 453, a reference region setting unit 454, a search region setting unit 455, a search unit 456, a long image creation unit 457, and a pixel value calculation unit 458. Have

  The image creating unit 451 creates the first image and the second image by assigning a predetermined gradation to the pixel value of the projection data. For example, in the case of 8-bit gradation, a gradation value (density value) from 0 to 255 is assigned to the pixel value of the shooting data. For example, in the case of 10-bit gradation, a gradation value (density value) from 0 to 1023 is assigned to the pixel value of the shooting data. Thereby, a first image and a second image are created. In the following description, the gradation values (density values) of the first image and the second image are referred to as pixel values.

  In this embodiment, the reference area described below is set using the pixel values of the first image and the second image. However, the reference area is set using the pixel values of the shooting data as they are. May be performed.

  In the following description, the first image and the second image are combined based on the pixel values of the first image and the second image, but the first image and the second image are combined based on the pixel value of the shooting data. You may stick together.

  The overlapping area calculation unit 452 calculates a first overlapping area that is an overlapping part with the second image in the first image, and a second overlapping area that is an overlapping part with the first image in the second image. Calculation is performed based on the position of the X-ray tube 11 and the position of the X-ray detector 22 in imaging.

  In the present embodiment, the overlapping area calculation unit 452 calculates the first overlapping area and the second overlapping area within the area excluding the image of the edge of the X-ray irradiation field.

  Next, calculation of the first overlapping area and the second overlapping area will be described with reference to FIGS. FIG. 4 is a conceptual diagram of long imaging in the X-ray diagnostic apparatus. In long imaging, as shown in FIG. 4, when the positions of the X-ray tube 11 and the X-ray detector 22 are changed, the position of the X-ray tube 11 is fixed, and the X-ray detector 22 The position may be changed.

Next, a case where the first overlapping region and the second overlapping region are calculated in the long imaging in which the position of the X-ray tube 11 is fixed and the position of the X-ray detector 22 is changed will be described with reference to FIG. To do. FIG. 5A is a conceptual diagram of long imaging in which the position of the X-ray tube 11 is fixed and the position of the X-ray detector 22 is changed in the body axis direction (Y direction) of the subject. In this long photographing, the width w of the first overlapping region and the second overlapping region can be calculated by the following equation (1).
w = Ly- (Yf1-Yf2) (1)

  Here, Ly is the size in the Y direction of the X-ray detector 22, Yf1 is the position in the Y direction after the change of the X-ray detector 22, and Yf2 is the position in the Y direction before the change of the X-ray detector 22. Represents. Note that (Yf1-Yf2) represents the movement distance of the X-ray detector 22 in the Y direction.

  The width w of the first overlapping region and the second overlapping region that can be obtained by Expression (1) is a case where the long shooting is performed along the body axis direction (Y direction). When long shooting is performed along the X direction (body axis direction), the widths w of the first overlap area and the second overlap area are obtained by rewriting Y in Expression (1) to X. Can do.

  In the following description, it is assumed that the body axis direction, which is the direction of long shooting, is the Y direction, but when the body axis direction is the X direction, similarly, by rewriting Y in the formula to X, It is possible to use an expression.

  Next, details of the first overlapping area and the second overlapping area will be described with reference to FIG. In FIG. 5B, the first image is shown on the lower side and the second image is shown on the upper side in the drawing. In FIG. 5B, when the first overlap region is overlapped with the second overlap region, the point (0, 0) on the coordinates of the first image is the point (x1, y1) on the coordinates of the second image. It corresponds to.

  The first overlapping area in the first image is a range from a point (0, 0) to a point (Lx, Ly− (Yf1−Yf2)) on the coordinates.

Further, the point y1 on the y-axis of the second image can be obtained by the following equation (2).
y1 = Ly- {Ly- (Yf1-Yf2)} (2)
This is y1 = Yf1-Yf2.
Therefore, the second overlapping region in the second image is a range from the point (0, Yf1-Yf2) to the point (Lx, Ly) on the coordinates.

  Next, calculation of the first overlap region and the second overlap region when the position of the X-ray tube 11 moves will be described with reference to FIG. FIG. 6 is a conceptual diagram of long imaging in which the positions of the X-ray tube 11 and the X-ray detector 22 are changed in the body axis direction (Y direction) of the subject.

The width w of the first overlap area and the second overlap area can be calculated as follows. First, the overlapping area w1 above Yfn at the subject position can be obtained by the following equation (3).
w1 = SPD / SID * (w / 2 + Yfn−Yt2) − (Yfn−Yt2)
... (3)
Here, SPD represents the distance from the X-ray tube 11 to the subject position (subject position), and SID represents the distance from the X-ray tube 11 to the X-ray detector 22.

Similarly, the overlapping area w2 below Yfn at the subject position can be obtained by the following equation (4).
w2 = SPD / SID * (w / 2 + Yt1-Yfn)-(Yt1-Yfn)
(4)

From the equations (3) and (4), the width w ′ of the overlapping area at the subject position can be obtained by the following equation (5).
w '= SPD / SID * {w + (1-SID / SPD) * (Yt1-Yt2)}
... (5)

The width wn of the overlapping region on the X-ray detector 22 can be obtained by the following equation (6) obtained by multiplying w ′ by SID / SPD.
wn = w + (1-SID / SPD) * (Yt1-Yt2) (6)
This can be replaced by the following equation (7).
wn = Ly- (Yf1-Yf2) + (1-SID / SPD) * (Yt1-Yt2) (7)

Next, the differential value calculation unit 453 will be described with reference to FIGS. The differential value calculation unit 453 obtains the pixel having the maximum absolute value of the differential value of the pixel value. For example, when the positions of adjacent pixels are x1 and x2 and the pixel values of each pixel are fx1 and fx2, the differential value (df / dx) of the pixel value can be obtained by the following equation (8). .
(Df / dx) = (fx1-fx2) / (x1-x2) (8)

  FIG. 7 is a diagram for explaining the first image and the second image before and after photographing by changing the position of the X-ray detector or the like. In FIG. 7, the first image is shown on the lower side and the second image is shown on the upper side in the drawing. In the first image and the second image shown in FIG. 7, the hatched portions are the first overlapping region and the second overlapping region.

  FIG. 8 is a diagram illustrating a first example of a procedure for setting a reference region within the first overlapping region. As shown in FIG. 8A, the differential value calculation unit 453 obtains a pixel having a large absolute value of the differential value of the pixel value in the first overlapping region.

  FIG. 9 is a diagram showing a second example of the procedure for setting the reference area. As shown in FIG. 9A, the differential value calculation unit 453 obtains a first pixel that is a pixel having a large absolute value of the differential value of the pixel value in the first overlapping region, and centers the first pixel. The second pixel that is the pixel having the largest absolute value of the differential value of the pixel value next to the first pixel may be obtained within the peripheral region of a predetermined size. Furthermore, the differential value calculation unit 453 may obtain a third pixel that is a pixel having the absolute value of the differential value of the pixel value next to the second pixel in the peripheral region.

  FIG. 10 is a diagram illustrating a third example of a procedure for setting a reference region. As illustrated in FIG. 10A, the differential value calculation unit 453 may obtain a peripheral area having a predetermined size centered on a pixel having a minimum pixel value in the first overlapping area. The peripheral area is determined in advance by the site of the subject. For example, in FIG. 10B, the peripheral region has a width equal to or greater than the width of the lower limb in the X direction.

  Note that the pixel value calculation unit 458 obtains a pixel having a minimum pixel value in the first overlapping region as follows. First, the pixel value calculation unit 458 obtains pixel values of pixels in a predetermined order within the first overlap region, sets the obtained pixel value as the minimum pixel value, and stores the position of the pixel. The pixel value calculation unit 458 obtains the pixel value of the next pixel in a predetermined order, compares the obtained pixel value with the pixel value of the stored pixel, sets the smaller pixel value as the minimum pixel value, The position of the pixel is stored.

  The pixel value calculation unit 458 repeats this procedure for all the pixels in the first overlapping region. The pixel value of the pixel stored at that time is minimized. In this way, the pixel value calculation unit 458 obtains a pixel having a minimum pixel value.

  Furthermore, as shown in FIG. 10C, the differential value calculation unit 453 obtains the first pixel in which the absolute value of the differential value of the pixel value is maximum in the peripheral region. As described above, the differential value calculation unit 453 includes the second pixel having the maximum absolute value of the differential value of the pixel value next to the first pixel and the next pixel in the peripheral region of the first pixel. You may make it obtain | require the 3rd pixel from which the absolute value of the differential value of a value becomes the maximum.

  As shown in FIG. 8B, the reference area setting unit 454 sets a reference area having a predetermined size centered on a pixel having a large absolute value of the differential value of the pixel value in the first overlapping area. To do.

  In addition, the reference area setting unit 454 obtains a first pixel that is a pixel having a large absolute value of the differential value of the pixel value in the first overlapping area by the differential value calculation unit 453, and sets the center around the first pixel. When obtaining the second pixel in the peripheral area of the specified size and further obtaining the third pixel in the peripheral area, as shown in FIG. 9B, the first pixel, the second pixel, and the third pixel are obtained. A reference area having a predetermined size including pixels may be set.

  Further, the reference area setting unit 454 obtains a peripheral area of a predetermined size centered on the pixel having the smallest pixel value in the first overlap area, and the differential value calculation section 453 determines the area within the peripheral area. When obtaining a pixel having the maximum absolute value of the differential value of the pixel value, a reference area having a predetermined size is set around the maximum pixel value as shown in FIG. You may do it.

  FIG. 11 is a diagram illustrating a fourth example of a procedure for setting a reference region. As shown in FIGS. 11A and 11B, the reference area setting unit 454 has a predetermined size centered on a pixel having a minimum pixel value in the first overlap area. When a peripheral region is obtained and the first pixel and the second pixel are obtained within the peripheral region, a reference region having a predetermined size including the first pixel and the second pixel may be set.

  Next, the search area setting unit 455 will be described with reference to FIG. FIG. 12A is a diagram for explaining the first image and the second image before and after changing the position of the X-ray detector 22 or the like in the long imaging. FIG. 12A is the same as FIG. 7 described above, but is a diagram in which the reference area setting unit 454 sets the reference area in the first overlapping area.

  FIG. 12B is an explanatory diagram in the case where the search area is set based on the position in the second overlapping area opposite to the reference area in the first overlapping area.

  The search area setting unit 455 sets a search area based on the position in the second overlapping area that is opposite to the reference area, based on the position information of the X-ray tube 11 and the X-ray detector 22. Here, the search area is determined in advance in consideration of the shake of the subject and the error of the position of the set search area. The predetermined search area is an area wider than the size of the reference area and is about half or less than the size of the second overlapping area. The search area setting unit 455 sets the search area having a predetermined size.

  Further, the position in the second overlapping area facing the reference area is a position where the reference area is arranged in the second overlapping area when the first image is superimposed on the second image.

  FIG. 13 is an explanatory diagram in the case of creating a long image of the bone part and the vicinity of the bone part. The search area setting unit 455 sets a search area, which is a rectangular area drawn by a broken line in FIG. 13A, based on the position in the second overlapping area facing the reference area.

The positional relationship between the reference area and the search area will be described with reference to FIG. 12B. The coordinates of the upper left point in the first image and the second image are (0, 0), and the upper left coordinates in the reference area. When (Xk, Yk) is set, the upper left coordinates (Xk ′, Yk ′) at the position in the second overlapping region opposite to the reference region can be obtained by the following equations (9) and (10). .
Xk ′ = Xk (9)
Yk ′ = Ly− (wn−Yk) (10)
Here, Ly represents the size of the X-ray detector 22 in the Y direction, and wn represents the width of the overlapping region in the X-ray detector 22.

  Next, the search unit 456 will be described. The search unit 456 searches the search area for a pattern that is the same as or similar to the pixel value pattern in the reference area, and obtains the position of the found pattern. Here, “the same or similar pattern” corresponds to “the same pattern” in the claims.

  The storage device 42 stores the pixel value pattern of the reference area and all the pixel values of the search area as array data. The search unit 456 reads the pixel value pattern (array data) in the reference area from the storage device 42, reads the pixel value pattern (predetermined part of the array data) in the search area, and compares both patterns. When one comparison is completed, the search unit 456 reads a pattern of pixel values (a predetermined portion of the array data) in the search area in a predetermined order (for example, from a pixel shifted by one pixel).

  The search unit 456 obtains a position when the pixel value pattern in the search area is most similar to the pixel value pattern in the reference area.

  As shown in FIG. 13 (a), the search unit 456 searches the search area for an area having the same pattern as the pixel value pattern of the reference area, or is most similar to the pixel value pattern of the reference area. The searched area is searched, and the position of the area having the same pattern or the position of the most similar area is obtained.

  The search unit 456 may search all the pixel values of the search area, and a similar condition (for example, a threshold value) is provided, and the similar degree satisfies the condition (when the threshold value is exceeded). ) Position may be obtained. This makes the search faster.

  Next, the long image creation unit 457 will be described. The long image creation unit 457 pastes the first image and the second image by relatively moving the position of the reference region to the position of the region searched for by the search unit 456.

  FIG. 13B shows a mode in which the long image creation unit 457 relatively moves the position of the reference region to the position of the region searched for by the search unit 456.

  The search unit 456 may calculate the amount of deviation in the X direction and the Y direction, and the long image creation unit 457 may paste the first image and the second image based on the amount of deviation.

  The display control unit 50 displays a long image on the monitor 60. The network output unit 51 transmits long image data to the server 71 and the printer 73 via a LAN (local area network). The server 71 stores the long image data in the storage device, and displays the long image on the monitor 72 under a predetermined condition.

(Operation)
Next, a procedure for creating a long image will be described with reference to FIG. The long image is created by pasting a plurality of images, but for the sake of simplicity, the following long image is created by pasting the first image and the second image. Created.

  The image creation unit 451 creates a first image and a second image (step S101). The creation of the first image and the second image is performed as follows. The X-ray tube 11 and the X-ray detector 22 are set at each position. At this time, the respective positions of the X-ray tube 11 and the X-ray detector 22 are acquired. Before and after, X-ray imaging is performed. In X-ray imaging, imaging data is acquired by the X-ray detector 22.

  Next, the position of at least one of the X-ray tube 11 or the X-ray detector 22 is changed along the body axis direction (for example, the Y direction) of the subject. At this time, the respective positions of the X-ray tube 11 and the X-ray detector 22 are acquired. Before and after, X-ray imaging is performed. In X-ray imaging, imaging data is acquired by the X-ray detector 22.

  The X-ray detector 22 corrects the pixel value of each imaging data and outputs the corrected data to the image processing device 40. The input unit 41 of the image processing apparatus 40 temporarily stores pixel value data. The input unit 41 transfers the data to the storage device 42 according to an instruction from the control unit 43.

  The control unit 43 instructs the image creation unit 451 to create an image. The image creating unit 451 creates the first image and the second image by reading each shooting data stored in the storage device 42 and assigning a predetermined gradation value (density value) to the pixel value of each shooting data. .

  Next, the overlapping area calculation unit 452 calculates the first overlapping area and the second overlapping area based on the positions of the X-ray tube 11 and the X-ray detector 22 (step S102).

  When the X-ray tube 11 is captured with the position fixed and when the X-ray tube 11 is captured with the position changed, the overlapping area calculation unit 452 determines the first overlapping area and the second overlapping area. The formula used when calculating is different.

  Expressions (1), (6), and (7) described above are expressions used when the first image and the second image overlap in the Y direction. If the first image and the second image overlap in the X direction, X and Y in the equation may be replaced.

  Next, the reference area setting unit 454 sets a reference area within the first overlapping area (step S103). The procedure for setting the reference area will be described later.

  Next, the search area setting unit 455 sets a search area in the second overlapping area (step S104). The search area setting unit 455 sets the search area at a position corresponding to the reference area in the second overlapping area. Further, the search area setting unit 455 sets the search area by a predetermined number of pixels with respect to the size of the reference area (the number of pixels in the X direction and the Y direction).

  Next, the image creation unit 451 performs image processing on the reference area and the search area. For example, the image processing includes compression processing and frequency processing. In the compression process, the image creation unit 451 reduces each image in the reference area and the search area by a predetermined factor. The image processing includes gradation processing. The image creation unit 451 converts the gradation of the reference area and the search area using a predetermined conversion curve.

  Next, the search unit 456 searches the search area for a pattern that is the same as or similar to the pixel value pattern of the reference area, and obtains the position of the searched pattern (step S105). The search unit 456 searches for a pattern having the same or similar pixel value, and obtains a position when the pixel value pattern in the search area is the same as or most similar to the pixel value pattern in the reference area.

  Since the search unit 456 searches for a search area narrower than the second area, it is possible to quickly search for a pattern that is the same as or similar to the pattern of the pixel value of the reference area from the search area.

  Next, the long image creation unit 457 pastes the first image and the second image by relatively moving the pixel value pattern of the reference region to the position of the pattern found by the search unit 456. Together (step S106).

  Next, a reference area setting procedure that is omitted from the description will be described in detail with reference to FIG. First, the pixel value calculation unit 458 obtains a pixel having a minimum pixel value in the first overlapping region (step S201). For example, the pixel at the edge of the bone has the minimum pixel value.

  Next, the differential value calculation unit 453 obtains a peripheral region having a predetermined size centered on a pixel having a minimum pixel value (step S202).

  Next, the differential value calculation unit 453 obtains the first pixel in which the absolute value of the differential value of the pixel value is maximum within the peripheral region (step S203).

  For example, the differential value calculation unit 453 obtains a first pixel that is a pixel having the maximum absolute value of the differential value of the pixel value as follows. First, the differential value calculation unit 453 calculates the absolute value of the differential value of the pixel value of the pixel in a predetermined order within the peripheral region, sets the absolute value of the calculated differential value as the maximum absolute value, and stores the position of the pixel. To do. The differential value calculation unit 453 obtains the absolute value of the differential value of the pixel value of the next pixel in a predetermined order, compares the absolute value of the obtained differential value with the absolute value of the stored differential value, and calculates the larger one. Is set as the maximum absolute value, and the position of the pixel is stored.

  The differential value calculation unit 453 repeats the above procedure for all the pixels in the peripheral region. At that time, the absolute value of the stored differential value is maximized. In this way, the differential value calculation unit 453 obtains the first pixel that has the maximum absolute value of the differential value.

  Next, the differential value calculation unit 453 obtains a peripheral area of a predetermined size of the first pixel (step S204). The peripheral area of the first pixel is determined in advance by the part of the subject.

  Next, the differential value calculation unit 453 obtains a second pixel that has the second largest absolute value of the differential value after the first pixel (step S205). The obtained second pixel is shown in FIG.

  Next, the reference area setting unit 454 sets a reference area having a predetermined size including the first pixel and the second pixel (step S206). The set reference area is shown in FIG.

  In the above-described embodiment, in the reference region setting procedure, in order to paste the bone portion and the image around the bone portion that tend to have small pixel values, first, the peripheral region of the pixel having the smallest pixel value is selected. The pixel value calculation unit 458 obtains, and then the differential value calculation unit 453 obtains the first pixel in the peripheral region, and the reference region setting unit 454 sets the reference region based on the first pixel. However, it is not limited to this. For example, the differential value calculation unit 453 obtains the first pixel having the maximum absolute value of the differential value of the pixel value in the first overlapping region, and the reference region setting unit 454 determines the reference region based on the first pixel. It may be set.

  In addition, a peripheral region of a pixel having a minimum pixel value in the first overlap region is obtained, and then a first pixel is obtained in the peripheral region, and a pixel having a minimum pixel value in the first overlap region The procedure (program) for setting the reference area may be configured to be switched between directly obtaining the first pixel in the first overlapping area without obtaining the peripheral area.

  Furthermore, although the reference area setting unit 454 sets the reference area including the first pixel and the second pixel, the present invention is not limited to this. For example, the reference area setting unit 454 may set a reference area having a predetermined size centered on the first pixel.

  Furthermore, although the overlap region calculation unit 452 has calculated the first overlap region and the second overlap region by excluding the image of the X-ray field edge, the overlap region calculation unit 452 intentionally includes the X-ray field edge. One overlap area and second overlap area may be calculated.

  In the above embodiment, the reference area setting unit 454 sets the area including the two pixels of the first pixel and the second pixel as the reference area, but the third pixel, the fourth pixel, etc. 3 A reference area including the above pixels may be set.

  Further, when the differential value calculation unit 453 obtains a plurality of pixels (for example, the first pixel, the second pixel, the third pixel,...) Having a large absolute value of the differential value of the pixel value in the first overlapping region. Alternatively, a threshold value may be provided for the differential value, and a plurality of pixels in which the absolute value of the differential value of the pixel value exceeds the threshold value may be obtained.

  Furthermore, before the search unit 456 searches the search area for a pattern that is the same as or similar to the pixel value pattern of the reference area, the search unit 456 applies a spatial filter that emphasizes edges to the reference area and the search area (image compression processing and It showed frequency search) and then searched for pixel value patterns. The spatial filter may be, for example, a band pass filter.

  The search unit 456 may directly search the search area for a pattern that is the same as or similar to the pixel value pattern in the reference area without applying a spatial filter, and obtain the position of the searched pattern. good.

  In the above embodiment, the long image is created by pasting the first image and the second image, but the number of images to be pasted may be three or more.

Moreover, although the case where the first image and the second image overlap in the Y direction has been described in the above embodiment, the present invention can also be applied to the case where two images overlap in the X direction.
Furthermore, the program may be read by setting a storage medium storing a program for executing steps S101 to S106 in the input device of the X-ray diagnostic apparatus.

It is a block diagram which shows the structure of the X-ray diagnostic apparatus which concerns on one embodiment of this invention. It is a block diagram which shows the structure of a X-ray detector. It is a block diagram which shows the structure of the calculating part of an image processing apparatus. It is a conceptual diagram of long imaging in an X-ray diagnostic apparatus. (A) is a conceptual diagram in the case of taking a long image by fixing the position of the X-ray tube, changing the position of the X-ray detector. (B) is a figure explaining an overlap area. These are conceptual diagrams in the case of taking a long image by changing the positions of the X-ray tube and the X-ray detector. It is a figure for demonstrating the 1st image and 2nd image before and behind image | photographing by changing positions, such as an X-ray detector. It is a figure which shows the 1st example of the procedure which sets a reference | standard area | region within a 1st overlap area | region. It is the figure which showed the 2nd example of the procedure which sets a reference | standard area | region. It is a figure which shows the 3rd example of the procedure which sets a reference | standard area | region. It is a figure which shows the 4th example of the procedure which sets a reference | standard area | region. It is explanatory drawing in the case of setting a search area | region based on a reference | standard area | region. It is explanatory drawing in the case of creating the long image of a bone part and the bone part vicinity. It is a flowchart which shows the procedure which produces a long image. It is a flowchart which shows the procedure which sets a reference | standard area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 X-ray tube holding apparatus 20 Solid stand 30 X-ray high voltage apparatus 40 Image processing apparatus 41 Input part 42 Memory | storage device 43 Control part 45 Operation part 451 Image creation part 452 Overlapping area calculation part 453 Differential value calculation part 454 Reference area setting part 455 Search area setting unit 456 Search unit 457 Long image creation unit 458 Pixel value calculation unit 50 Display control unit 60 Monitor

Claims (7)

A first image and a first image before and after changing the position based on each imaging data acquired by the X-ray detector in each imaging where the position of at least one of the X-ray detector or the X-ray tube is changed. An image creation unit for creating two images;
X-ray detection of a first overlapping region that is an overlapping portion with the second image in the first image and a second overlapping region that is an overlapping portion with the first image in the second image. An overlapping area calculation unit for calculating the position based on the position information of the X-ray tube and the X-ray tube;
A differential value calculation unit for obtaining a pixel having the maximum absolute value of the differential value of the pixel value in the first overlapping region;
A reference area setting unit for setting a reference area having a predetermined size centered on a pixel having a maximum absolute value of the differential value of the pixel value;
A search area setting unit for setting a search area in the second overlapping area based on the reference area;
Searching for the same pattern as the pixel value pattern of the reference area from the search area, and searching for the position of the searched pattern,
A long image creation unit that pastes the first image and the second image by relatively moving the position of the pixel value pattern of the reference region to the position of the pattern searched by the search unit;
An X-ray diagnostic apparatus comprising: A first image and a first image before and after changing the position based on each imaging data acquired by the X-ray detector in each imaging where the position of at least one of the X-ray detector or the X-ray tube is changed. An image creation unit for creating two images;
X-ray detection of a first overlapping region that is an overlapping portion with the second image in the first image and a second overlapping region that is an overlapping portion with the first image in the second image. An overlapping area calculation unit for calculating the position based on the position information of the X-ray tube and the X-ray tube;
A first pixel that is a pixel having a maximum absolute value of a differential value of a pixel value in the first overlapping region is obtained, and the first image is obtained in a peripheral region having a predetermined size of the first pixel. A differential value calculation unit for obtaining a second pixel that is a pixel having a second absolute value of the differential value of the pixel value,
A reference area setting unit for setting a reference area of a predetermined size including the first pixel and the second pixel;
A search area setting unit for setting a search area in the second overlapping area based on the reference area;
Searching for the same pattern as the pixel value pattern of the reference area from the search area, and searching for the position of the searched pattern,
A long image creation unit that pastes the first image and the second image by relatively moving the position of the pixel value pattern of the reference region to the position of the pattern searched by the search unit;
An X-ray diagnostic apparatus comprising: A pixel value calculation unit for obtaining a pixel having a minimum pixel value in the first overlapping region;
The differential value calculation unit obtains a pixel having a maximum absolute value of the differential value of the pixel value within a peripheral region having a predetermined size of the pixel having the minimum pixel value. The X-ray diagnostic apparatus according to claim 1 or 2. In the gap between the X-ray tube and the X-ray detector, an X-ray aperture device for forming an X-ray irradiation field on the X-ray detector is disposed,
The said overlap area | region calculation part calculates the said 1st overlap area | region and the said 2nd overlap area | region containing the image of the edge of the said X-ray irradiation field, Either of Claim 1 or Claim 2 characterized by the above-mentioned. X-ray diagnostic equipment.   The search area setting unit sets the search area at a position in the second overlapping area that is opposite to the reference area, based on position information of the X-ray detector and the X-ray tube, and The X-ray diagnostic apparatus according to claim 1, wherein a search area is set larger than the reference area. First and second images before and after changing the position based on imaging data acquired by the X-ray detector in each imaging where the position of at least one of the X-ray detector or the X-ray tube is changed. Creating an image;
A first overlapping region that is an overlapping portion with the second image in the first image, and a second overlapping region that is an overlapping portion with the first image in the second image; Calculating based on position information of the X-ray tube;
Obtaining a pixel having a minimum pixel value in the first overlap region;
A first pixel that is a pixel within the first overlapping region and having a maximum absolute value of a differential value of the pixel value in a peripheral region having a predetermined size of the pixel with the minimum pixel value is obtained. And determining a second pixel that is a pixel whose absolute value of the differential value of the pixel value is next to that of the first pixel in a peripheral region of a predetermined size of the first pixel;
Setting a reference area of a predetermined size including the first pixel and the second pixel;
Setting a search area in the second overlapping area based on the reference area;
Finding the same pattern as the pixel value pattern of the reference area from the search area, and finding the position of the found pattern;
Pasting the first image and the second image by moving the position of the pixel value pattern of the reference region relative to the position of the pattern searched by the search unit;
An X-ray image processing method comprising:   A computer-readable storage medium storing a program for executing the steps of the X-ray image processing method according to claim 6.