JP2008173311A - Apparatus and method for tomography, and composing apparatus and index member therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct displacement and generate clear tomograms in a simple constitution when performing a tomography. <P>SOLUTION: An actual position of an irradiation section 101 is calculated based on the position of an identifier 107 projected on projection image data obtained by X-ray projection to a chart section 106 from different directions. A plurality of projection image data obtained by the X-ray projection images of the subject 120 from different directions are composed based on the calculated value to generate a tomogram of the subject 120. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tomographic image photographing apparatus and a technique related to them.

  In recent years, an X-ray diagnostic apparatus for tomosynthesis that can observe a tomographic plane of a specimen at an arbitrary depth by combining a plurality of image data obtained by X-ray imaging of the specimen from different directions has been proposed. (Patent Document 1).

  One known method for synthesizing image data is a shift addition method. In this method, a plurality of obtained image data are shifted to perform addition processing. An arbitrary tomographic plane image can be formed by adjusting the shift amount (shift amount).

JP 2001-510698 A

  However, it is conceivable that a horizontal or vertical shift occurs in the positional relationship between the X-ray source and the detector. As a result, there is a problem that a clear tomographic plane image cannot be obtained by any image synthesis method represented by the shift addition method.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a technique capable of correcting a positional deviation with a simple configuration and generating a clear tomographic image when performing tomographic imaging.

  In order to solve the above-described problem, the first invention is to detect a transmission image of a specimen from different directions and obtain a plurality of transmission image data, and combine the plurality of transmission image data to obtain the specimen. And a part identifying structure that is installed at a position that has a predetermined relationship with the place where the specimen is placed and that can be identified by a transmission image detected by the detection unit. A tomographic plane having a reflecting unit for reflecting the detection result of the site identification structure obtained by the detection unit in a synthesis process of the plurality of transmission image data of the specimen. An image capturing device.

  2nd invention is 1st invention, Comprising: The said reflection means calculates | requires the synthetic | combination parameter of these transmission image data obtained about the said specimen based on the detection information of the said part identification structure.

  3rd invention is 2nd invention, Comprising: The said chart part has an identifier which can identify the height from the said detection part to the said site | part identification structure with the transmission image which the said detection part detects.

  A fourth invention is any one of the first to third inventions, and includes a plurality of chart units installed at different positions relative to the detection unit.

  5th invention is 4th invention, Comprising: The said detection part detects the some permeation | transmission image by each detecting the transmitted electromagnetic wave irradiated to the test substance sequentially from a different direction, The said chart part is which Even in the region where the transmitted electromagnetic wave is irradiated from the irradiation position, it is provided on both sides of the intermediate portion of the locus of the irradiation position.

  6th invention is 4th or 5th invention, Comprising: The said detection part detects the some permeation | transmission image by each detecting the transmission electromagnetic wave irradiated to the test substance sequentially from a different direction, The said chart part Are provided separately in a direction parallel to the locus of the irradiation position.

  In a seventh aspect of the invention, a predetermined detection unit detects a transmission image of a chart unit that is installed at a position having a predetermined relationship with a place where a specimen is placed and has a part identification structure that can identify a part by a transmission image. A chart detection step for obtaining transmission image data and obtaining a detection result of the part identification structure by a detection unit; and a sample detection step for obtaining transmission image data by detecting transmission images of the specimen from different directions by the detection unit, respectively. Using the detection result of the part identification structure of the chart unit, and combining the plurality of transmission image data of the specimen to generate a tomographic plane image of the specimen, Is the method.

  The eighth invention is different from the set of the sample and the chart unit that is installed at a position having a predetermined relationship with the place where the sample is placed and has a site identification structure capable of site identification by a transmission image. Using the detection step of obtaining transmission image data from a direction and a synthesis parameter obtained from the detection result of the part identification structure in the transmission image data, the portion related to the sample is synthesized in the transmission image data, and the sample A tomographic image capturing method, comprising: a synthesizing step of generating a tomographic image of the same.

  According to a ninth aspect of the invention, there is provided identification means for identifying a position of a predetermined part of the chart based on first image data obtained by transmission images from different directions of the predetermined chart, and position information of the predetermined part. A tomographic plane image synthesizing apparatus comprising a synthesizing unit that synthesizes a plurality of second image data obtained by transmission images from different directions of a specimen while using a synthesis parameter obtained based on the basis.

  A tenth aspect of the invention is used to determine a synthesis parameter for obtaining a tomographic plane image of a specimen by synthesizing a plurality of transmission image data obtained by detecting transmission images of the specimen from different directions. An index member that can be detected by (a) a two-dimensional identifier having a shape that can be detected by a transmission image or (b) a transmission image at a location that is in a predetermined positional relationship from a predetermined reference plane of the index member. The indicator member is provided with a two-dimensional arrangement of a plurality of identifiers.

  According to the first invention, the detection unit used for detecting the specimen is used to detect the site identification structure of the chart part, and the detection result is reflected in the synthesis of a plurality of transmission image data for the specimen. Therefore, it is possible to capture the positional deviation of the device elements with a simple configuration and generate a clear tomographic image.

  According to the second invention, the reflecting means obtains a composite parameter of a plurality of transmission image data obtained for the specimen based on the detection information of the part identification structure, so that the positional deviation of the device element is captured with a simple configuration. It is possible to generate a clear tomographic image.

  According to the third aspect of the invention, the chart unit has an identifier that can identify the height from the detection unit to the site identification structure based on the transmission image of the chart unit, so that a clearer tomographic image is easily generated. It becomes possible.

  According to the fourth aspect, since a plurality of chart portions are provided, a clearer tomographic image can be generated.

  According to the fifth invention, the chart portions are provided on both sides of the intermediate portion of the locus of the irradiation position in the region where the transmitted electromagnetic wave is irradiated from any irradiation position. Stable transmitted electromagnetic wave data can be obtained, and error bias is reduced.

  According to the sixth invention, the chart part is provided separately in a direction parallel to the locus of the irradiation position. Therefore, when the transmission image data is obtained more accurately as the irradiation position of the transmitted electromagnetic wave is closer, each time point is obtained. Thus, it is possible to perform highly accurate processing using transmission image data of the chart portion provided at a position close to the irradiation position.

  According to the seventh invention, a plurality of transmission image data of the specimen is generated by using the detection result of the part identification structure of the chart portion, and the tomographic plane image of the specimen is generated. Since the parameters can be determined, it is not necessary to install a chart portion in the vicinity of the specimen when scanning the specimen.

  According to the eighth invention, the tomographic plane image of the specimen is generated by synthesizing the part of the transmission image data related to the specimen while using the synthesis parameter obtained from the detection result of the part identification structure in the transmission image data. Sample detection and synthesis parameter determination can be performed in a single scan.

  According to the ninth aspect, the position of the predetermined part of the chart is specified based on the first image data, and the second image data is synthesized using the synthesis parameter obtained based on the position. A clear image can be generated regardless of the displacement of the element.

  According to the tenth invention, the indicator member is provided with a two-dimensional identifier having a shape detectable by a transmission image or a plurality of identifiers detectable by a transmission image. It becomes possible to apply as a chart part of invention of 8.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
Hereinafter, as an example of the tomographic image capturing apparatus according to the first embodiment of the present invention, a case where the chart portion is formed in a conical shape and a tomographic image is generated by tomosynthesis will be described.

<Configuration>
FIG. 1 is a diagram showing a schematic configuration of a tomographic image photographing apparatus 100 according to the first embodiment of the present invention. The specimen 120 as a target for generating a tomographic plane by the apparatus 100 is typically the body of the subject, and the subject is placed on the placement unit 104. The ellipse in the figure schematically shows the body of the subject.

  The irradiation unit 101 irradiates a wave for obtaining a transmission image of the specimen, specifically, an electromagnetic wave, more specifically an X-ray. The irradiation unit 101 is movably connected to the guide unit 102 and moves on the guide unit 102 in accordance with control from the irradiation position control unit 103. Here, the irradiation position control unit 103 not only controls the position of the irradiation unit 101 on the guide unit 102, but also controls the positional relationship of the mounting unit 104, that is, the specimen 120 with respect to the irradiation unit 101 and the guide unit 102. As a result, the spatial relationship between the irradiation unit 101 and the mounting unit 104 changes relatively.

  In FIG. 1, the guide part 102 is formed in a substantially arc shape, and the irradiation part 101 irradiates X-rays in the direction from the arc toward the focal point. However, the present invention is not limited to this. The guide part 102 may be formed in a substantially linear shape, and X-rays may be irradiated in a direction perpendicular to the guide part 102. In either case, X-rays are sequentially irradiated from a plurality of directions on a predetermined side (upper side in the illustrated example) of the specimen 120 so as to be suitable for imaging by tomosynthesis, and transmitted electromagnetic wave data (transmitted X-ray data) is obtained. To get.

  The placement unit 104 is disposed so as to satisfy a predetermined relative arrangement condition with respect to the irradiation unit 101 connected to the guide unit 102 by the connecting unit 105, and X-rays irradiated from the irradiation unit 101. The specimen 120 is placed within the irradiation range. Specifically, the mounting portion 104 is fixed to a predetermined position by the connecting portion 105 on the side where the focal point of the arc defined by the guide portion 102 is located. The mounting portion 104 is made of a material that substantially transmits X-rays due to low X-ray absorption, and the attenuation coefficient (absorption coefficient) for X-rays is known.

  The chart unit 106 (generally an index member) is disposed within the X-ray irradiation range irradiated from the irradiation unit 101 at the upper part of the mounting unit 104 (the side on which the specimen 120 is mounted), and is positioned at the X-ray irradiation position. Accordingly, the transmitted electromagnetic wave data is formed in different shapes. The chart unit 106 is made of a material having a known attenuation coefficient for X-rays. Specifically, it is formed of a material having an attenuation coefficient close to that of an imaging target, for example, an organ of a subject. In the present embodiment, two chart portions 106 formed in a substantially conical shape are arranged, but the shape and number are not limited thereto.

  Further, the chart unit 106 includes an identifier 107 that can identify the height from the mounting unit 104 or the detection unit 108 described later and the relative positional relationship with the irradiation unit 101 based on the transmitted electromagnetic wave data. Specifically, the identifier 107 is a scale 107a to 107c provided on the circumference of the cross section with respect to the height direction from the reference plane with the bottom surface of the chart portion 106 formed in a substantially conical shape as the reference plane. . The scales 107a to 107c may be formed of a material having an attenuation coefficient different from the material of the portion other than the scales 107a to 107c of the chart unit 106, or the chart unit 106 may be shaved to form a scale. Thereby, the identifier 107 appears as a ring (or a part of the ring) in the transmission electromagnetic wave data of the chart unit 106, and the height from the detection unit 108 can be identified.

  These are one example of a part identification structure that identifies each part of the chart unit 106 with transmitted X-rays. These scales 107a to 107c are preferably formed of a material that blocks most of the X-rays, such as metal, so that a clear image can be detected. From this point of view, if attention is paid to the site identification structure, an X-ray “projection” image can be obtained instead of an X-ray “transmission” image, but in the description of the present embodiment, an X-ray image of the specimen 120 is obtained. It is called “transmitted electromagnetic wave data” in the same way. The chart unit 106 is not necessarily fixed to the mounting unit 104 and may be detachable.

  The detecting unit 108 detects the electromagnetic wave transmitted from the specimen 120 and / or the chart unit 106, which is irradiated from the irradiation unit 101 and placed on the placement unit 104, and the placement unit 104 as transmitted electromagnetic wave data. Specifically, the irradiation unit 101 includes a specimen 120, that is, a substantially planar two-dimensional X-ray image detector that detects X-rays immediately below the mounting unit 104. An X-ray image transmitted through 120 and / or the chart unit 106 and the mounting unit 104 is detected as transmitted electromagnetic wave data. The detected transmitted electromagnetic wave data is converted into image data corresponding to a visible image and stored in the storage unit 109 as projection image data.

  Here, the irradiation unit 101, the guide unit 102, the mounting unit 104, and the detection unit 108 satisfy the following positional relationship. That is, the irradiation range of the X-rays irradiated from the irradiation unit 101 at any position on the guide unit 102 covers the mounting unit 104 almost entirely, and from any position on the guide unit 102. Even the X-rays irradiated are detected by the detection unit 108.

  For example, a nonvolatile memory is applied to the storage unit 109, and the transmission electromagnetic wave data detected by the detection unit 108 and the irradiation position of the irradiation unit 101 when the transmission electromagnetic wave data is detected are stored.

  The correcting unit 110 corrects the composite parameter of the transmitted electromagnetic wave data based on the transmitted electromagnetic wave data of the chart unit 106. Details of processing performed by the correction unit 110 will be described in detail later.

  The generation unit 111 includes a plurality of transmitted electromagnetic wave data stored in the storage unit 109, that is, projection image data, an irradiation position of the irradiation unit 101 when each projection image data is detected, and a correction value calculated by the correction unit 110. Based on the above, tomographic image data of the specimen 120 is generated. Specifically, the generation unit 111 generates tomographic plane image data while temporarily storing projection image data in the RAM 112 as appropriate in cooperation with the RAM 112 which is temporary storage means. A method for generating tomographic image data will be described in detail later.

  The display unit 113 is configured using, for example, a CRT or LCD, and visually displays a planar image. Specifically, the display unit 113 displays the tomographic plane image expressed by the tomographic plane image data generated by the generation unit 111 and other plane images expressed by the projection image data stored in the storage unit 109. Various image information and numerical character information are displayed.

  The input receiving unit 114 includes, for example, a keyboard 114a and a mouse 114b. The keyboard 114a operates and inputs various commands including character keys, numeric keys, function keys, and the like. The mouse 114 b is a pointing device that receives an operation input desired by the user in the image displayed on the display unit 113. The keyboard 114a and the mouse 114b can cooperate to input various commands.

The control unit 115 can execute the following two processes by controlling the irradiation unit 101, the irradiation position control unit 103, the detection unit 108, the storage unit 109, the correction unit 110, the generation unit 111, and the display unit 113. .
(1) Correction of transmitted electromagnetic wave data due to displacement of irradiation unit 101 (correction process):
The position (x, y, z) of the irradiation unit 101 is calculated based on the transmission electromagnetic wave data obtained by irradiating the chart unit 106 with X-rays, and the irradiation position control unit 103 when the transmission electromagnetic wave data is obtained. Is compared with the position (X, Y, Z) of the irradiation unit 101 (where the position (X, Y, Z) is not shown), which is controlled by (1). (Referred to as “correction value”). These positions (X, Y, Z) are control command values, and can also be referred to as design values.
In this irradiation part position correction, a plurality of scales 107a to 107c of the chart part 106 are used. The mutual identification of the projection images by the plurality of scales 107a to 107c is performed by using the largest circle 21 (see FIG. 2) among the plurality of circles included in the projection image obtained by the detection unit 108 as the projection image by the lowest scale 107c. And the circle 22 having the center Q ′ farthest from the center Q of the circle 21 can be extracted as a projection image by the uppermost scale 107a.
(2) Generation of tomographic plane image data (generation process):
Based on the correction value detected in the correction step, transmitted electromagnetic wave data obtained by sequentially irradiating the specimen 120 with X-rays from different directions is synthesized to generate a tomographic plane image of the specimen 120.

  The detailed control contents of the control unit 115 will be described in detail later. Here, the irradiation position control unit 103, the storage unit 109, the correction unit 110, the generation unit 111, and the RAM 112 may be built in a general PC (Personal Computer).

<Correction process>
FIG. 2 is a schematic diagram showing the detection principle of the correction value. Here, a method in which the correction unit 110 detects a correction value will be described. Here, the placement unit 104 is omitted. In addition, the meaning of the various quantities shown by FIG. 2 is as follows. However, here, a plane parallel to the image detection plane of the detection unit 108 is referred to as an “xy plane” defined by the x-axis and the y-axis, and a direction perpendicular thereto is referred to as a “z-direction”.
O = the focal position of the arc where the irradiation unit 101 moves (the center position of a circle defining an arc);
L = distance from the center O to the irradiation unit 101;
θ = the angle formed by the imaginary line connecting the center O and the irradiation unit 101 with the z direction;
x = position on the x-axis of the irradiation unit 101;
y = position on the y-axis of the irradiation unit 101;
z = position on the z-axis of the irradiation unit 101;
H = distance of the detection unit 108 from the center O;
a = the position of the scale on the x-axis;
b = position on the y-axis of the scale;
h _a = distance of the detector 108 from the scale 107a;
h _b = distance of the detection unit 108 from the scale 107b;
Q = center position of the circle 21 defined by the projected image of the scale 107c;
Q ′ = the center position of the circle 22 defined by the projected image of the scale 107a;
Q ″ = center position of the circle 23 defined by the projected image of the scale 107b;
A _i = the position on the x-axis of the center Q ′ from the center Q;
B _i = position on the y-axis of the center Q ′ from the center Q;
A _j = position on the x-axis of the center Q ″ from the center Q;
B _j = the position on the y-axis of the center Q ″ from the center Q.

The correction value is calculated based on the transmitted electromagnetic wave data of the identifier 107 (scales 107a to 107c in FIG. 2). When the actual position of the irradiation unit 101 is assumed to be (x, y, z), among the plurality of transmitted radiation data, the center of the i-th transmitted radiation data D _i circle 22 defined by the projected image of the scale 107a in Position Q ′ (A _i , B _i , −H) satisfies the following expressions (1) and (2). Similarly, the center position Q ″ (A _j , B _j , −H) of the circle 23 defined by the projected image of the scale 107b also satisfies the following expressions (1) and (2). When a projection image is used, h _a = h _b is set.

  In the present embodiment, since two chart portions 106 are arranged (see FIG. 1), eight equations (1) and (2) can be obtained for one transmitted electromagnetic wave data D. Since there are three unknowns x, y, and z, if there is at least one transmitted electromagnetic wave data D obtained by irradiating X-rays from one position as in this example, correction values (that is, x, y, and z) X, y, z values as values obtained by correcting the design values X, Y, Z can be calculated. Once the correct value (x, y, z) of the position coordinates of the irradiation unit 101 is determined, an algorithm for performing image synthesis in tomosynthesis using them is known, and this can also be used in this embodiment.

  Here, the projected image of the scale 107a is a circle only when the irradiation unit 101 emits X-rays from directly above the chart unit 106, and becomes an ellipse when irradiated from another position, but the correction unit 110. Can correct the ellipse into a circle.

  In addition, even when only one chart unit 106 is used, the amount of information obtained by irradiating the chart unit with X-rays from one position (direction) by using a pyramid having an asymmetric bottom as a chart unit instead of a cone. Therefore, simultaneous equations necessary for specifying the unknowns x, y, and z can be obtained. In any case, if the values of the unknowns x, y, and z are specified, the value of the synthesis parameter at the time of image synthesis can be specified from them.

<Chart location>
The transmitted electromagnetic wave data D can be obtained as a clearer image as the irradiation unit 101 is closer. For this reason, the accuracy of the above-described correction processing varies depending on the installation position of the chart unit 106. FIG. 3 is a diagram illustrating an installation position of the chart unit 106. Specifically, a plurality of chart units 106 are prepared, and (1) in any region where the irradiation unit 101 can irradiate X-rays from any irradiation position, preferably an intermediate portion of the locus 31 of the irradiation position (preferably Positions on both sides (preferably positions symmetrical with respect to the trajectory 31) across the center), that is, positions that pass through the focal point of the arc defined by the guide portion 102 and are separated on both sides of the virtual plane to which the arc belongs (preferably Is provided in a plane symmetric with respect to the virtual plane) (see FIG. 3A);
(2) It is divided in a direction parallel to the trajectory 31 in which the irradiation unit 101 moves, and is provided at a position sandwiching the specimen 120 (see FIG. 3B);
There are other aspects.

  In the above aspect (1), it is possible to obtain the stable transmitted electromagnetic wave data D of the chart unit 106 from any irradiation position, and the error bias is reduced. Moreover, in said aspect (2), among the several chart parts 106 projected on each transmitted electromagnetic wave data D, the projection image nearer to the irradiation part 101 at that time, ie, a clearer chart part 106 It is possible to perform highly accurate processing using the projected image.

  These modes are appropriately selected by the operator of the tomographic imaging apparatus 100 in consideration of the shape of the specimen 120, that is, the shape and size of the body part of the subject to be imaged.

<Generation principle of tomographic image data>
One of the control contents of the control unit 115 is generation of tomographic plane image data of the specimen 120. Here, the generation principle of tomographic plane image data generated by the generation unit 111, that is, the principle of tomosynthesis will be described.

  FIG. 4 is a schematic diagram showing the principle of tomosynthesis. In tomosynthesis, a plurality of projection image data are obtained by irradiating the specimen 120 with electromagnetic waves that pass through the specimen 120, specifically, X-rays from different angles on a predetermined side of the specimen 120, and combining them. To obtain an image of the tomographic plane. As shown in FIG. 4, for example, a star element (☆) 121 and a round element (◯) 122 are shown as detection units schematically showing the internal structure (specifically, human tissue or lesion) of the specimen 120. When the detectors 108 are arranged in a direction perpendicular to the detection surface, X-rays are irradiated from different angles to obtain transmitted electromagnetic wave data D, that is, projection image data P (projection data identification symbol P is not shown). In the projection images 41 to 43 expressed by the plurality of projection image data P obtained in this way, the image position of each element differs according to the distance (height) from the detection surface. While utilizing this property, arbitrary tomographic plane image data is generated using a known image composition method.

<Shift addition method>
A known method for synthesizing a plurality of images in tomosynthesis is a shift addition method. FIG. 5 is a schematic diagram showing the principle of the shift addition method. This is based on each of the projection images 41 to 43 and the irradiation position (x, y, z) of the irradiation unit 101 when the projection image data P corresponding to each of the projection images 31 to 33 is detected. In this method, the projection image data P is added while the relative positions of the images 41 to 43 are sequentially shifted. Specifically, based on the correction value calculated by the above correction process, the irradiation position (X, Y, Z) controlled by the irradiation position control unit 103 is changed to the actual irradiation position (x, y, z). Calibration is performed, and addition processing of each projection image data P is performed while sequentially shifting the relative positions of the projection images 41 to 43 while using this as a synthesis parameter.

  As a result, it is possible to obtain data of the image 51 in which the star-shaped elements 121 that are faintly reflected in the projected images 41 to 43 are emphasized and the image 52 in which the round elements 122 are emphasized. That is, the image 41 is a tomographic image in which the cross section at the height where the star-shaped element 121 exists in the internal structure of the specimen 120 is emphasized, and the image 52 is the circular element 122 in the internal structure of the specimen 120. It is a tomographic plane image which emphasized the cross section of the existing height. Here, for the sake of simplicity of explanation, the images 51 and 52 are shown as examples generated by adding and synthesizing the projection image data P of the three projection images 41 to 43. Since P is acquired, it is possible to synthesize a large number of projection image data P. Further, the composition of the projection image data P does not necessarily need to use the shift addition method, and may be a filtered back projection method (FBPM) or the like.

<Operation>
By having the above-described configuration and using the above-described principle, the following operation can be performed. Here, the operation of the tomographic image capturing apparatus 100 will be described. In this embodiment, for the sake of convenience of explanation, a case where the information acquisition process for correction is performed prior to tomographic imaging of the specimen 120, that is, the acquisition of the transmission electromagnetic wave data D will be described as an example. The acquisition of the data D may be performed simultaneously in parallel.

  FIG. 6 is a flowchart showing the operation of the tomographic image capturing apparatus 100. First, a plurality of transmitted electromagnetic wave data D are detected by detecting transmitted electromagnetic waves sequentially irradiated on the chart unit 106 from different directions (detection step, step S601). Based on the transmitted electromagnetic wave data D detected in step S601, a correction value is calculated as a composite parameter obtained by correcting the positional deviation of the transmitted electromagnetic wave data D due to the deviation of the irradiation position (correction step, step S602).

  Specifically, the irradiation unit 101 is moved to one position in the movement locus, the chart unit 106 is irradiated with X-rays from that position, and the X-ray projection image is detected by the detection unit 108. Although only one scale 107 a is illustrated in FIG. 2, actually, three scales 107 a to 107 c are formed in the chart portion 106 as described with reference to FIG. 1. The X-ray projection images of these three scales 107a to 107c can be identified by the difference in the center position of the circle. In addition, detection of a circle in the projected image can be realized by using a known algorithm.

Therefore, two of the scales 107a to 107c, for example, the scales 107a and 107c, correspond to the expressions (1) and (2) while using the known values h _a and h _b as the respective heights h. Create two sets of formulas (four in total). Of the other quantities appearing in equations (1) and (2), H is known, θ is related to x and z by the following equation (3), and L is x, by the following equation (4): Associate y and z.

  By solving three of these six equations as simultaneous equations, the values of the unknowns x, y, and z can be specified. In addition, when all of the projected images of the scales 107a to 107c are used, eight equations can be obtained. By using these error theories, the unknowns x, y, and z can be specified with higher accuracy while using all of these equations. is there. In any case, the value of (x, y, z) as a synthesis parameter can be specified. In this embodiment, an arithmetic program for performing such data processing is set in the correction unit 110.

  Next, a plurality of transmitted electromagnetic wave data D is detected by sequentially irradiating the specimen 120 with X-rays from different directions (step S603). The transmitted electromagnetic wave data D detected in step S603 is synthesized with reference to the correction value to generate a tomographic plane image of the specimen 120 (generation step, step S604). As a result, the detection result of the site identification structure of the chart unit 106 can be reflected in the synthesis process of the plurality of transmitted electromagnetic wave data D for the specimen 120.

<Effect>
As described above, the region identification structure (identifier 107) of the chart unit 106 is detected using the detection unit 108 used for detecting the sample 120, and the detection result is obtained from the plurality of transmitted electromagnetic wave data D for the sample 120. By reflecting it in the composition, it is possible to capture the positional deviation of the device elements with a simple configuration and generate a clear tomographic image.

  Further, since the reflecting means (correction unit 110) obtains the composite parameters (x, y, z) of the plurality of transmitted electromagnetic wave data D obtained for the specimen 120 based on the detection information of the part identification structure (identifier 107), It is possible to capture the positional deviation of the device elements with a simple configuration and generate a clear tomographic image.

  In addition, the chart unit 106 has the identifier 107 (scales 107a to 107c) that can identify the height from the detection unit 108 to the site identification structure (identifier 107) based on the projected electromagnetic wave of the chart unit 106, so that it is clearer. A tomographic image can be easily generated.

  Further, by providing a plurality of chart sections 106, it becomes possible to generate a clearer tomographic plane image.

  Here, by providing the chart unit 106 on both sides of the intermediate portion of the locus 31 of the irradiation position in the region where the transmission electromagnetic wave is irradiated from any irradiation position, the transmission can be stably transmitted from any irradiation position. The electromagnetic wave data D can be obtained, and the error bias is reduced.

  Alternatively, when the chart part 106 is provided separately in a direction parallel to the locus 31 of the irradiation position, and the transmission electromagnetic wave data D is more accurate as the transmission position of the transmission electromagnetic wave is closer, the irradiation at each time point is performed. It becomes possible to perform highly accurate processing using the transmission electromagnetic wave data D of the chart unit 106 provided at a position close to the position.

  In addition, by using the detection result of the site identification structure (identifier 107) of the chart unit 106, a plurality of transmitted electromagnetic wave data D for the specimen 120 is synthesized to generate a tomographic plane image of the specimen 120, so that a chart in advance Since the synthesis parameters (x, y, z) can be determined by scanning, it is not necessary to install the chart unit 106 in the vicinity of the specimen 120 when scanning the specimen 120.

  Alternatively, using the composite parameter (x, y, z) obtained from the detection result of the part identification structure (identifier 107) in the transmitted electromagnetic wave data, the portion related to the specimen 120 in the transmitted electromagnetic wave data is synthesized and the tomogram of the specimen 120 is obtained. By generating a plane image, it is possible to detect the specimen 120 and determine the synthesis parameters (x, y, z) in one scan.

  Further, as the index member, a two-dimensional identifier having a shape that can be detected by transmitted electromagnetic waves or a two-dimensional arrangement of a plurality of identifiers that can be detected by transmitted electromagnetic waves is provided, so that the chart unit 106 of the first to eighth inventions is provided. It becomes possible to apply.

<Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the contents described above.

  For example, in the above-described embodiment, the case where the chart unit 106 is formed in a conical shape has been described as an example. However, the projection image may have a different shape depending on the irradiation position of the irradiation unit 101 (irradiation direction on the chart unit 106). It ’s fine. FIG. 7 is a schematic diagram illustrating a detection principle of a correction value using a modification of the chart unit 106. The placement unit 104 is omitted. As shown in FIG. 7, the chart unit 701 includes a rectangular plate 701 a parallel to the detection unit 108, and support legs 701 b that support the rectangular plate 701 a at a predetermined height from the detection unit 108. The square plate 701a includes corner portions 702a to 702d. The chart unit 701 is arranged at a predetermined position on the side of the mounting unit 104 on which the sample 120 is mounted.

Here, the meanings of various quantities not shown in FIG. 2 are as follows.
c, c _{t to} c _w = positions of the corners 702a to 702d on the x-axis;
d, d _{t to} d _w = positions of the corners 702a to 702d on the y axis;
C _{t to} C _w = positions of the corners 702a to 702d on the x-axis in the projected image;
D _{t to} D _w = positions on the y-axis of the corners 702a to 702d in the projection image.

The correction value is calculated based on the transmission electromagnetic wave data D of the rectangular plate 701a. Among the plurality of transmitted electromagnetic wave data D, in the i-th transmitted electromagnetic wave data D _i , the position of the corner 702a on the projected image, that is, the coordinates (C _t , D _t , −H) of the corner of the projected image 71 are as follows. The following expressions (5) and (6) are satisfied.

  In this modified example, four equations (5) and (6) can be obtained for each transmitted electromagnetic wave data D, and therefore, based on one transmitted electromagnetic wave data D, a correction value (about the position coordinates of the irradiation unit 101) is obtained. Correct (x, y, z)) can be calculated.

  In the above-described modification, for example, when fixing the support leg 701b to the placement unit 104, it may be difficult to maintain the accuracy of the height of the rectangular plate 701a from the detection unit 108. Therefore, it is possible to keep the height accuracy by applying the following modification.

  FIG. 8 is a diagram illustrating a modified example of the chart unit 701. As shown in FIG. 8, the chart section 801 has square plates 801a and 801b, and the square plates 801a and 801b are parallel to each other while maintaining a predetermined distance via a connecting leg 801c. It is connected to the. Then, the rectangular plates 801a and 801b are arranged at a predetermined height by the support legs 801d while maintaining a parallel positional relationship with the detection unit 108. Thereby, since the distance between the square plate 801a and the square plate 801b can maintain accuracy, the correction value is calculated more accurately based on the positions of the corner portions 802a to 802d and the corner portions 803a to 803d in the projected image. be able to.

In this case, two sets of equations corresponding to the equations (5) and (6) can be made corresponding to the upper and lower rectangular plates 801a and 801b. When the error of the height h _b of the lower rectangular plate 801b and Delta] h, the lower the height of the rectangular plate 801b is in (h _b + Δh), and the upper square plate 801a height h _a versa error Delta] h To (h _a + Δh). This is because the error in the distance between the upper and lower rectangular plates 801a and 801b is smaller than Δh. For this reason, compared with the case where Formula (5) and Formula (6) are comprised only about one square plate 701a, error (DELTA) h increases as an unknown number, However, by increasing the number of equations, it is the synthetic | combination parameter (x , Y, z) can be specified.

Thus, as a preferable aspect of the chart portion (generally, an index member), in a place having a known positional relationship from a predetermined reference surface (usually the bottom surface portion) of the index member,
(A) a two-dimensional identifier having a shape detectable by a projected image of electromagnetic waves, such as the ring of FIG. 2 or the rectangle of FIGS. 7 and 8; or
(B) For example, in the case where spherical identifiers that do not transmit electromagnetic waves are arranged in the corners 702a to 702d, 802a to 802d, and 803a to 803d in FIGS. Two-dimensional arrangement of identifiers;
It can comprise as what provided.

  In addition, the chart unit 106 is made portable and is temporarily placed at the time of X-ray imaging, and the design value for the position coordinates (x, y, z) of the irradiation unit 101 is corrected to an actual value. However, when a structure corresponding to the chart unit 106 is fixedly provided, the chart units 106, 701, and 801 are not forgotten to be prepared. Can be detected, and the actual value of the position coordinates (x, y, z) of the irradiation unit 101 can be obtained. In this case, since the apparatus does not have to hold the design values (default values) of the position coordinates (x, y, z), instead of “correcting” the existing default values, they are newly determined each time. You can also. Therefore, the present invention is not limited to “correcting” a synthesis parameter such as (x, y, z), and generally, the object can be achieved by “reflecting” the detection result of the chart unit 106 in image synthesis. .

  The composite parameter determined (or corrected) by the detection of the chart unit 106 may not be the position coordinates of the irradiation unit 101 but the height or inclination of the mounting unit 104 with respect to the detection surface of the detection unit 108. In this case, the apparatus is configured to execute the following process.

That is, when it is desired to synthesize a horizontal tomographic image of the specimen 120 at a height h _b on one of the plurality of scales 107a to 107c (for example, the scale 107b) of the chart unit 106, this height h _b is used as a synthesis parameter. As one of them, for example, a tomographic plane image M _b (not shown) of the specimen 120 is obtained by a shift addition method. By performing the synthesis at a height h _b of the scale 107b detecting unit 108 as a reference, the image plane to obtain the sectional images M _b by adopting a method as shown in FIG. 3, the scale of the chart portion 106 The image 107b should also appear.

  However, for example, if an error occurs in the height of the placement unit 104 with respect to the detection unit 108, an image of another scale (for example, the scale 107a) appears instead of the target scale 107b. Which of the scales 107a to 107c appears can be identified by the relationship between the shift amount of the scale image between the plurality of transmitted electromagnetic wave images and the diameter of the ring image. Not only when the image of a completely different scale 107a is replaced, but also when the image of two blurred scales 107a and 107b appears, the actual height is calculated by height interpolation based on the ratio of their sharpness. You can know the value of the height.

By finding this situation by visual image recognition or the operator, the thus obtained by What is not the image of the height h _b, sectional image of the specimen 120 at a height h _a of the scale 107a, or because it is found that sectional images at these mid-height, or warning to that effect, to calculate the height of the error (h _a -h _b), corrects the synthesis parameters using the same Then, it can be synthesized again.

  In addition, by forming a numerical mark indicating the height from the bottom surface of the chart unit 106 or the detection unit 108 as a scale of the chart unit 106 with a metal or the like, it is dispersed and fixed at locations corresponding to the respective heights. The numerical image appearing in the combined tomographic plane image is the height of the tomographic plane at that height, and thus the height of the tomographic plane can be accurately grasped. When the tomographic plane is not at the intended height, a tomographic plane image at the required height can be obtained by changing the synthesis parameter value as necessary and performing recombination.

  When using a chart portion in which the size or shape of the horizontal cross section varies continuously or stepwise depending on the height, the scale need not be formed. For example, in the case of using a conical chart portion, the diameter of the circle varies depending on the height of the cross section, and therefore the height of the cross section can be known by determining the diameter of the circle. Thus, a structure in which the shape and cross-sectional size of the chart body are changed in the height direction is also included in the concept of the site identification structure in the present invention.

  The present invention can also be realized as a data synthesizer separated from the shooting detection climate. That is, the position of a predetermined part of the chart is specified based on the first image data obtained by X-raying the predetermined chart from different directions, and the synthesis parameter obtained based on the positional information of the specified part is used. However, a plurality of second image data obtained by X-ray imaging of the specimen from different directions can be synthesized. Therefore, the present invention can also be configured as a synthesizing device for generating a tomographic plane image.

  As a result, the position of a predetermined part of the chart is specified based on the first image data, and the second image data is synthesized using the synthesis parameter obtained based on the position. Therefore, it is possible to generate a clear image.

1 is a diagram illustrating a schematic configuration of a tomographic image imaging apparatus according to a first embodiment of the present invention. It is a schematic diagram which shows the detection principle of a correction value. It is a figure which shows the installation position of a chart part. It is a schematic diagram which shows the principle of tomosynthesis. It is a schematic diagram which shows the principle of the shift addition method. It is a flowchart which shows operation | movement of a tomographic image imaging device. It is a schematic diagram which shows the detection principle of the correction value using the modification of a chart part. It is a figure which shows the modification of a chart part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Tomographic plane imaging device 101 Irradiation part 103 Irradiation position control part 106,701,801 Chart part 107 Identifier 107a-107c Scale 108 Detection part 110 Correction part 111 Generation part 115 Control part 120 Sample 702a-702d, 802a-802d, 803a ~ 803d Corner

Claims (10)

A detection unit for obtaining a plurality of transmission image data by detecting transmission images of specimens from different directions;
Combining means for combining the plurality of transmission image data to generate a tomographic image of the specimen;
A chart unit that is installed at a position that is in a predetermined relationship with the place where the specimen is placed, and that has a site identification structure that enables site identification by a transmission image detected by the detection unit;
The synthesizing means is
A tomographic image imaging apparatus, comprising: reflecting means for reflecting a detection result of the part identification structure obtained by the detection unit in a synthesis process of the plurality of transmission image data for the specimen. The tomographic image imaging device according to claim 1,
The reflection unit is a tomographic imaging apparatus that obtains a composite parameter of the plurality of transmission image data obtained for the specimen based on detection information of the part identification structure. The tomographic imaging apparatus according to claim 2,
The tomographic imaging apparatus, wherein the chart unit includes an identifier that can identify a height from the detection unit to the site identification structure by a transmission image detected by the detection unit. A tomographic image imaging device according to any one of claims 1 to 3,
A tomographic image imaging device comprising a plurality of chart units installed at different positions relative to the detection unit. The tomographic imaging apparatus according to claim 4,
The detection unit detects a plurality of transmitted images by detecting each transmitted electromagnetic wave sequentially irradiated on the specimen from different directions,
The chart unit is a tomographic image imaging device provided on both sides of an intermediate part of a locus of the irradiation position in a region where the transmitted electromagnetic wave is irradiated from any irradiation position. The tomographic image imaging device according to claim 4 or 5,
The detection unit detects a plurality of transmitted images by detecting each transmitted electromagnetic wave sequentially irradiated on the specimen from different directions,
The chart section is a tomographic image imaging device provided separately in a direction parallel to the locus of the irradiation position. Transmission image data is obtained by detecting a transmission image of a chart portion having a part identification structure that is installed at a predetermined relationship with a place where a specimen is placed and has a part identification structure by a transmission image by a predetermined detection unit. , A chart detection step of obtaining a detection result of the part identification structure by a detection unit;
A specimen detection step of obtaining transmission image data by detecting transmission images of specimens from different directions by the detection unit;
A tomographic plane imaging method comprising: a synthesis step of generating a tomographic plane image of the specimen by synthesizing the plurality of transmission image data of the specimen while using the detection result of the part identification structure of the chart unit . Transmission image data from different directions with respect to a set of a chart unit having a part identification structure that is installed at a predetermined relationship with a place where the specimen is placed and has a part identification structure that can be identified by a transmission image Obtaining a detection step;
A synthesis step of generating a tomographic plane image of the specimen by synthesizing a part related to the specimen in the transmission image data using a synthesis parameter obtained from the detection result of the part identification structure in the transmission image data. , Tomographic imaging method. Specifying means for specifying a position of a predetermined part of the chart based on first image data obtained by transmission images from different directions of the predetermined chart;
A tomographic plane image synthesis comprising: synthesis means for synthesizing a plurality of second image data obtained by transmission images from different directions of the specimen while using a synthesis parameter obtained based on position information of the predetermined part. apparatus. An index member used to determine a synthesis parameter when obtaining a tomographic image of the specimen by synthesizing a plurality of transmission image data obtained by detecting transmission images of specimens from different directions,
In a place having a predetermined positional relationship from a predetermined reference surface of the index member,
(A) a two-dimensional identifier having a shape detectable by a transmission image, or
(B) An index member provided with a two-dimensional arrangement of a plurality of identifiers detectable by a transmission image.

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