JP4045442B2 - Calibration method of rotation center axis in X-ray CT apparatus and X-ray CT apparatus - Google Patents

Description

  The present invention relates to a rotation center axis calibration method in an industrial X-ray CT apparatus and an X-ray CT apparatus suitable for carrying out the method.

  In the X-ray CT apparatus, generally, as schematically shown in FIG. 9, a rotation table for mounting the sample W between the X-ray source 91 and the X-ray detector 92 to give rotation. 93, the sample W is irradiated with X-rays while rotating the rotary table 93, and the X-ray transmission information of the sample W taken at every predetermined rotation angle is used as the rotation center axis R of the rotary table 93. A tomographic image of the sample along the orthogonal plane is reconstructed.

  In such an X-ray CT apparatus, since the tomographic image is built around the rotation center axis, in order to obtain a tomographic image centered on an arbitrary position of the sample W, the sample W is placed on the rotary table 93. It is desirable to be able to move in a direction orthogonal to the rotation center axis R. Therefore, as shown in the figure, a moving mechanism such as an xy table 94 is provided on the rotary table 93, and the sample W is placed on the xy table 94. Is often employed to obtain X-ray transmission information (see, for example, Patent Document 1).

  Further, instead of providing the rotary table 93, a fixed sample stage is arranged, and the pair of the X-ray source and the X-ray detector is placed around the rotation center axis passing through the sample stage while maintaining the positional relationship with each other. Some have been known to have a rotating configuration. Even in such a configuration, since the tomographic image is constructed around the rotation center axis of the pair of the X-ray source and the X-ray detector, a moving mechanism such as an xy table similar to the above is provided on the sample table, It is preferable to employ a configuration in which the sample can be moved with respect to the rotation center axis.

  In any of the X-ray CT apparatuses as described above, the rotation center axis R of the rotary table 93 or the rotation center axis of the pair of the X-ray source and the X-ray detector is projected onto the X-ray detector 92. It is essential to know the coordinate information of the position.

  In order to obtain this rotation center axis projection position information, conventionally, as shown in FIG. 10, a holding member 95a made of a material that easily transmits X-rays such as acrylic resin has a high X-ray absorption rate such as tungsten. A rotation center axis calibration jig (phantom) 95 having a structure provided with a wire 95b made of material is used, and this rotation center axis calibration jig 95 is provided in the X-ray CT apparatus having the rotation table 93 shown in FIG. The rotation center axis calibration jig 95 is placed on a moving mechanism such as an xy table 94 disposed on the rotation table 93, and the rotation axis of the wire 95b is in the vicinity of the rotation center axis R of the rotation table 93. The projection position coordinates of the rotation center axis R on the X-ray detector 92 are obtained by using X-ray transmission information from the X-ray detector 92 for each predetermined rotation angle. calculate

Even in an X-ray CT apparatus configured to rotate a pair of an X-ray source and an X-ray detector, a rotation center axis calibration jig equivalent to the above is placed on a moving mechanism such as an xy table on a sample table. Then, the pair of the X-ray source and the X-ray detector is rotated, and the projection position coordinates of the rotation center axis on the X-ray detector are calculated using the X-ray transmission information taken at every predetermined rotation angle.
JP 2002-310943 A

  By the way, in the X-ray CT apparatus having the sample moving mechanism such as the xy table on the rotary table or the sample table as described above, the rotation center axis calibration jig is placed on the moving mechanism to obtain the X-ray transmission information. When calculating the rotation center axis projection position, various errors such as backlash of the moving mechanism are surely generated, and there is a problem that the calibration result is adversely affected.

  INDUSTRIAL APPLICABILITY In the X-ray CT apparatus having a sample moving mechanism such as an xy table on a rotary table or a sample stage, the rotation center axis can be more accurately calibrated using a rotation center axis calibration jig. It is an object to provide a method and an apparatus.

  In order to solve the above-described problem, the rotation center axis calibration method in the X-ray CT apparatus according to the present invention includes a sample stage disposed between an X-ray source and an X-ray detector that are arranged to face each other, and While rotating a pair of line detectors or a sample stage around a predetermined rotation center axis, using the X-ray transmission information collected at every predetermined rotation angle by irradiating the sample with X-rays, A table having a sample moving mechanism for at least one axis for moving or tilting the sample is placed on the sample stage, and a tomographic image of the sample along an orthogonal plane is reconstructed. In an X-ray CT apparatus configured to mount a sample, a method for obtaining coordinates of a projection position of the rotation center axis, wherein a wire having a high X-ray absorption rate is straightened by a holding member having a low X-ray absorption rate Hold in shape In a state where the holding member of the calibration jig is fixed to the sample stage and the wire is positioned so as to be along the rotation center axis in the vicinity of the rotation center axis. X-ray irradiation is performed while rotating a pair of a radiation source and an X-ray detector or a sample stage, and X-ray transmission information of a calibration jig for each predetermined angle is collected, and the rotation center is obtained from the collected X-ray transmission information. It is characterized by calculating the coordinates of the projected position of the axis (claim 1).

  In order to solve the above-described problems, an X-ray CT apparatus according to the present invention includes an X-ray source and an X-ray detector arranged to face each other, a rotary table arranged therebetween, and an upper surface of the rotary table. And a sample table equipped with a sample moving mechanism for mounting or moving or tilting the sample, and irradiating X-rays while the sample is mounted on the sample table and the rotary table is rotated. An X-ray CT provided with a tomogram reconstruction calculation means for reconstructing a tomogram of the sample along a plane orthogonal to the rotation center axis using the X-ray transmission information collected at every predetermined rotation angle. In the apparatus, the rotary table holds a rotation center axis calibration jig composed of a wire made of a material having a high X-ray absorption rate and a holding member made of a material having a low X-ray absorption rate that holds the wire linearly. Part Is provided with a calibration jig mounting mechanism for detachably or removably mounting the wire along the rotation center axis in the vicinity of the rotation center axis (Claim 2). .

  Furthermore, another X-ray CT apparatus of the present invention that achieves the same object is provided with an X-ray source and an X-ray detector arranged opposite to each other and a pair of the X-ray source and the X-ray detector at a predetermined center of rotation. A rotating mechanism that rotates about an axis; a sample stage disposed between the X-ray source and the X-ray detector; and at least one for placing or moving or tilting the sample disposed on the sample stage. A sample table equipped with an axis sample moving mechanism, and a sample mounted on the sample table, irradiated with X-rays while rotating the pair of the X-ray source and the X-ray detector, and sampled at every predetermined rotation angle In the X-ray CT apparatus provided with tomographic image reconstruction means for reconstructing a tomographic image of a sample along a plane orthogonal to the rotation center axis using the X-ray transmission information obtained, X-ray absorption is performed on the sample stage. A wire made of a high-rate material and an X-ray that holds the wire in a straight line A holding member of a rotation center axis calibration jig composed of a holding member made of a low-yield material is detachably or removably mounted so that the wire follows the rotation center axis in the vicinity of the rotation center axis. This is characterized in that a calibration jig mounting mechanism is provided.

  According to the method of the present invention, an X-ray CT apparatus having a sample moving mechanism such as an xy table on a sample stage (rotating table) having a rotating mechanism, or a pair of an X-ray source and an X-ray detector is rotated. In any X-ray CT apparatus provided with a sample moving mechanism such as an xy table on a fixed sample table, the rotary table is directly mounted on the rotating table without placing the rotating axis calibration jig on the sample moving mechanism. Alternatively, it is fixed on the sample stage, irradiated with X-rays in a state where the wire is arranged along the rotation center axis in the vicinity of the rotation center axis, and the sample stage (rotation table) or X-ray source and X-ray detector The projection position coordinates of the rotation center axis are obtained using the X-ray transmission information acquired at every predetermined angle by rotating the pair around the rotation center axis, so that the position of the calibration jig does not depend on the sample moving mechanism. No rotating table Will depend on the sample stage, without being affected by backlash or the like of the sample moving mechanism such as a xy table, it is possible to determine the projection position of precisely the rotation center axis.

  According to the X-ray CT apparatus of the second aspect of the present invention, in an apparatus provided with a sample moving mechanism such as an xy table on a rotary table, a rotation center axis comparison in which a wire is held by a holding member on the rotary table. A calibration jig mounting mechanism is provided for mounting the correct jig so that the wire is detachable or retractable so that the wire follows the rotation center axis in the vicinity of the rotation center axis. The rotation center axis calibration jig can be fixed directly to the sample, enabling accurate calibration without being affected by the backlash of the sample moving mechanism and collecting X-ray transmission information of the sample. In this case, it is possible to prevent the X-ray transmission information of the sample from being affected by removing or retracting the calibration jig.

  Furthermore, according to the X-ray CT apparatus of the invention according to claim 3, the pair of the X-ray source and the X-ray detector is rotated, and a sample moving mechanism such as an xy table is provided on the sample table provided therebetween. In an X-ray CT apparatus, a rotation center axis calibration jig equivalent to the above is attached to a sample stage so that the wire is detachable or retractable along the rotation center axis in the vicinity of the rotation center axis. Since the correct jig mounting mechanism is provided, the rotation center axis calibration jig can be fixed directly to the sample stage when the rotation center axis is calibrated. Accurate calibration is possible without being affected, and when collecting X-ray transmission information of the sample, it is possible to prevent the X-ray transmission information of the sample from being affected by removing or retracting the calibration jig. Can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of the vicinity of a rotary table, which is a configuration of the main part of an embodiment in which the present invention is applied to an X-ray CT apparatus of a type in which a sample is rotated by a rotary table, and FIG. And an enlarged sectional view (B) of the main part.

  In this example, the X-ray source and the X-ray detector are the same as the conventional X-ray CT apparatus shown in FIG. 9, for example, the X-ray source on the left in the horizontal direction in FIG. The X-ray detector is arranged on the side, but this point is not different from the conventional apparatus, and therefore the X-ray source and the X-ray detector are omitted in order to avoid complication of the drawing.

  The feature of this example is that the sample is placed on the rotary table 1 for rotating the sample around the rotation center axis R along the vertical axis (z axis), and the sample is placed on a horizontal plane (xy plane). In an X-ray CT apparatus provided with an xy table 2 as a sample moving mechanism for moving above, an attachment 3 is fixed on the rotary table 1, and the xy table 2 is placed on the attachment 3. In addition, the attachment 3 is provided with a calibration jig mounting portion 31.

  That is, the attachment 3 is formed by integrally forming a substantially cylindrical calibration jig mounting portion 31 at one end of a flat plate member 32, and the xy table 2 is disposed on the flat plate member 32.

  The calibration jig 4 has a structure in which a wire 42 made of a material having a high X-ray absorption rate, such as tungsten, is held straight by a holding member 41 made of a material having a low X-ray absorption rate, such as acrylic, equivalent to the conventional one described above. One end of the calibration jig 4 is fixed to the take-out member 5, and the take-out member 5 can be detachably attached to the calibration jig attachment portion 31.

  As shown in FIG. 2B, the calibration jig attaching / detaching portion 31 has a structure in which, for example, a two-stage cylindrical convex portion 31a is formed on the top of the cylindrical member. Two steps of recesses 5a and 5b are formed on the front and back in the vicinity of the end opposite to the side to which 4 is fixed, and the recesses 5a and 5b are dimensioned to fit closely to the protrusion 31a. These convex portions 31a and concave portions 5a or 5b form a so-called in-row structure so that the take-out member 5 can be attached to and detached from the calibration jig mounting portion 31 with high positioning accuracy.

  FIG. 1 and FIG. 2 (A) show a state where one concave portion 5a of the take-out member 5 is attached to the convex portion 31a of the calibration jig attachment portion 31, and in this state, the calibration jig 4 and the take-out member 5 are xy. The wire 42 of the calibration jig 4 is not in contact with the table 2 and is in a state along the rotation center axis R in the vicinity of the rotation center axis R of the turntable 1 above the xy table 2.

  In the calibration operation of the rotation center axis, that is, the operation of obtaining the coordinates of the projection position of the rotation center axis R of the rotary table 1 on the X-ray detector, the calibration jig 4 is in the state shown in FIG. 1 or FIG. While irradiating X-rays, the turntable 1 is rotated by a predetermined angle, and X-ray transmission information of the calibration jig 4 is captured at each rotation angle. From the X-ray transmission information of each rotation angle, the position of the wire 42 is read, and the coordinates of the center position of the shake in the horizontal direction on the X-ray detector are calculated to calculate the projection position coordinates of the rotation center axis. Ask for.

  When collecting X-ray transmission information of an actual sample, the calibration jig 4 is removed from the calibration jig mounting portion 31 together with the take-out member 5 from the state shown in FIGS. 1 and 2, and a perspective view is shown in FIG. Then, the opposite concave portion 5 b is fitted into the convex portion 32 a of the calibration jig mounting portion 32. As a result, the calibration jig 4 is removed from the upper side of the xy table 2 and is directed vertically downward on the side of the rotary table 1, and is in a state of being retracted from the space between the X-ray source and the X-ray detector. When the sample W is placed on the xy table 2 and irradiated with X-rays, only the X-rays transmitted through the sample W are incident on the X-ray detector.

  What should be particularly noted in the above embodiment is that the calibration jig 4 is substantially positioned and fixed with respect to the rotary table 1 regardless of the xy table 2, and thus, xy. The X-ray transmission image of the wire 42 at the time of calibration always correctly represents the positional relationship with the rotation center axis R of the rotary table 1 without being affected by the backlash of the table 2, and the projection of the rotation center axis R. The position can be obtained with high accuracy.

  Here, in the above embodiment, the recesses 5a and 5b are provided on the front and back of the take-out member 5 to which the calibration jig 4 is fixed, and one of them is fitted into the projection 31a of the calibration jig mounting part 31. Thus, the use state and the retracted state of the calibration jig 4 can be selected. However, the carry-out member 5 is formed only with the concave portion 5a that fits into the convex portion 31a when the calibration jig 4 is used, and in the non-use state. As shown in FIG. 4, the calibration jig 4 can be removed together with the take-out member 5.

  Further, as the retracting structure of the calibration jig 4, for example, using a hinge mechanism or the like, there are a use state positioned above the xy table 2 and a non-use state (retreat state) facing downward on the side of the rotary table 1. It can also be configured to be selectable.

  Furthermore, in the above embodiment, the example in which the xy table 2 is arranged as the sample moving mechanism on the rotary table 1 has been shown, but the present invention is not limited to this, and an arbitrary moving mechanism is adopted. be able to. That is, the degree of freedom as a moving mechanism on the rotary table 1 is five axes of translation in the x, y, and z directions orthogonal to each other and rotation around the x, y axes. The present invention can be applied to an X-ray CT apparatus in which a mechanism for moving to any one axis or a plurality of axes is mounted on the rotary table 2. FIG. 5 shows an example in which a sample moving mechanism 6 having a rotating mechanism around a horizontal axis is mounted on the rotary table 1, (A) is during calibration, and (B) is when collecting X-ray transmission information of the sample W. Is shown. Also in this example, the calibration jig mounting portion 31, the calibration jig 4 and the take-out member 5 can be the same as those in the above-described embodiment. However, the mechanism for attaching / detaching or retracting the calibration jig 4 should be determined in consideration of the following points in relation to the sample moving mechanism.

  That is, the wire 42 of the calibration jig 4 is arranged at the position where the sample W is placed when the sample W is imaged during calibration, and the retracting or attaching / detaching mechanism of the calibration jig 4 is used for the X-ray source and the X-ray during the calibration. It does not exist in a position that creates a shadow that affects the X-ray fluoroscopic image of the wire 42 between the detectors (provided that it is a structure having an extremely low X-ray absorption rate such as carbon or some resin). And the calibration jig 4 and its attachment / detachment / retraction mechanism do not affect the X-ray transmission information of the sample W and do not disturb the operation of the sample movement mechanism 6 when imaging the sample W. I must.

  Further, in each of the above embodiments, the calibration jig 4 is detoured outside the xy table 2 or the sample moving mechanism 6 on the rotary table 1 by the take-out member 5 or the like, and the wire 42 has the rotation center axis R. Although the example is shown in the vicinity, the calibration jig 4 can be detachably mounted inside the sample moving mechanism such as the xy table 2. An example is shown in FIG. In this figure, (A) shows a state during calibration, and (B) shows a state during imaging of the sample W.

  In this example, an attachment 7 for detachably mounting the calibration jig 4 on the rotary table 1 is fixed, and a sample moving mechanism 8 is disposed on the attachment 7 to move the sample. The mechanism 8 is formed with a through hole 8a for allowing the calibration jig 4 to pass therethrough. At the time of calibration, the lower end portion of the calibration jig 4 is attached to the attachment 7 through the through hole 8a as shown in FIG. As a result, the calibration jig 4 is positioned with respect to the rotary table 1 regardless of the sample moving mechanism 8. Further, when imaging the sample W, the calibration jig 4 is detached from the attachment 7 as shown in FIG. Thereby, the calibration jig | tool 4 can be made not to interfere with the imaging of the sample W. The through hole 8a may be used as a groove, and when the calibration jig 4 is not used, it may be accommodated in the groove by a hinge mechanism or the like and tilted downward from the sample mounting surface of the sample moving mechanism 8.

  Each of the above embodiments shows an example in which the present invention is applied to an X-ray CT apparatus in which an X-ray source and an X-ray detector are arranged so that a line connecting them is orthogonal to the rotation center axis R. However, the present invention can be equally applied to a so-called inclined X-ray CT apparatus in which the line connecting the X-ray source and the X-ray detector is not orthogonal to the rotation center axis. An example is schematically shown in FIG.

  In the example of FIG. 7, the upper surface side of the rotary table (mechanism) 11 is supported by an apparatus frame or the like, the attachment 13 is fixed to the lower surface thereof, and the xy moving mechanism 12 is attached via the attachment 13. The xy moving mechanism 12 is configured such that a sample table 122 is suspended via a suspension member 121 and a sample is mounted on the sample table 122. The X-ray source 14 is disposed obliquely below the sample table 122, and the X-ray detector 15 is disposed obliquely above the sample table 122 so as to face the X-ray source 14. A calibration jig mounting portion 131 equivalent to the example of FIG. 1 is integrally formed on the attachment 13, and one end of the take-out member 5 similarly to the example of FIG. 1 is attached to the calibration jig mounting portion 131. For example, it fixes so that it may not fall using a screw etc., the calibration jig | tool 4 equivalent to each previous example is fixed to the taking-out member 5, and the wire 42 of the calibration jig | tool 4 is in the mounting state of the taking-out member 5. In the vicinity of the rotation center axis R of the turntable 11, the rotation table 11 is configured to follow the rotation center axis R.

  Also in the above configuration, the calibration jig 4 is directly positioned and fixed with respect to the rotary table 11 regardless of the xy moving mechanism 12, and the rotary table 11 is rotated in this state to By collecting the X-ray transmission information, the projection position coordinates of the rotation center axis R can be accurately obtained without being affected by the backlash or the like of the xy movement mechanism 12. Further, when the sample is imaged, the calibration jig 4 is removed or retracted together with the take-out member 5 so that these are positioned between the X-ray source 14 and the X-ray detector 15 and affect the X-ray transmission information of the sample. Never give.

  Furthermore, in each of the above embodiments, an example in which the present invention is applied to an X-ray CT apparatus configured to rotate a table on which a sample is mounted has been described. However, an X-ray source and X-ray detection can be performed without rotating the sample. The present invention is equally applicable to an X-ray CT apparatus of the type that rotates a pair of instruments around a sample. An example of this is schematically shown in FIG.

  In the example of FIG. 8, the X-ray source 21 and the X-ray detector 22 are supported by a common support member 23, and a sample stage 24 whose upper surface forms a reference plane is disposed inside the X-ray source 21 and the X-ray detector 22. A sample moving mechanism 25 for moving the sample W such as an xy table is arranged on the top. Then, the support member 23 is rotated around the rotation center axis R by a rotation mechanism (not shown), whereby the pair of the X-ray source 21 and the X-ray detector 22 is rotated around the sample W.

  An attachment 26 in which a calibration jig mounting portion 261 is integrally formed is fixed to one end equivalent to that shown in FIG. 1 on the sample stage 24, and the sample moving mechanism 25 is disposed on the attachment 26. ing. Then, the calibration jig 4 equivalent to each of the previous examples is detachably or removably mounted on the calibration jig mounting portion 261 of the attachment 26, and in the mounted state, the wire 42 is in the vicinity of the rotation center axis R. It is located along the rotation center axis R.

  Also in this example, the calibration jig 4 is positioned directly on the sample stage 23 regardless of the sample moving mechanism 25, and the pair of the X-ray source 21 and the X-ray detector 22 is rotated. By collecting the X-ray transmission information of the calibration jig 4, the projection position coordinates of the rotation center axis R can be accurately obtained without being affected by the backlash of the sample moving mechanism 25. In addition, the calibration jig 4 does not interfere with the imaging by removing or retracting the calibration jig 4 during imaging of the sample.

  In each of the above embodiments, an example is shown in which the attachment is fixed on the rotary table or the sample stage, and the calibration jig is detachably or removably attached via the attachment. Of course, the attachment is not necessarily required if the mounting portion for the calibration jig is formed on the table itself.

It is a perspective view which shows the principal part structure of embodiment which applied this invention to the type of X-ray CT apparatus which rotates a sample with a turntable. It is the front view (A) of FIG. 2, and the principal part expanded sectional view (B). It is a perspective view which shows the imaging state of the sample W in embodiment shown in FIG. 1, FIG. It is a perspective view which shows the principal part structure of other embodiment of this invention. It is a perspective view which shows the principal part structure of other embodiment of this invention, (A) is the use condition (state at the time of calibration) of a calibration jig, (B) is the non-use state (sample) of a calibration jig. FIG. It is a perspective view which shows the principal part structure of other embodiment of this invention, (A) is the use condition (state at the time of calibration) of a calibration jig, (B) is the non-use state of a calibration jig ( It is a figure which shows the imaging state of a sample. It is a principal part block diagram of embodiment which applied this invention to the tilt type X-ray CT apparatus. It is a perspective view which shows the principal part structure of embodiment which applied this invention to the type of X-ray CT apparatus which rotates the pair of a X-ray source and a X-ray detector around a sample. It is a schematic diagram which shows the structural example of the conventional X-ray CT apparatus. It is explanatory drawing of the example of the calibration method which calculates | requires the projection position of the rotation center axis | shaft of the conventional X-ray CT apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation table 2 xy table 3 Attachment 31 Calibration jig mounting part 31a Convex part 4 Calibration jig 41 Holding member 42 Wire 5 Take-out member W Sample

Claims (3)

A sample stage is arranged between an X-ray source and an X-ray detector that are arranged opposite to each other, and a pair of X-ray source and X-ray detector or a sample stage is rotated around a predetermined rotation center axis while the sample stage is rotated. Reconstructing a tomographic image of the sample along a plane perpendicular to the rotation center axis using X-ray transmission information obtained by irradiating X-rays and collected at every predetermined rotation angle, on the sample stage, In an X-ray CT apparatus in which a table having at least one axis driving mechanism for moving or tilting a sample is mounted and the sample is mounted on the table, the projection position of the rotation center axis is determined. A method for obtaining coordinates,
Using a calibration jig in which a wire having a high X-ray absorption rate is linearly held by a holding member having a low X-ray absorption rate, the holding member of the calibration jig is fixed to the sample stage, and the wire Is irradiated with X-rays while rotating a pair of an X-ray source and an X-ray detector or a sample stage while being positioned in the vicinity of the rotation center axis and along the rotation center axis. A method of calibrating a rotation center axis in an X-ray CT apparatus, wherein X-ray transmission information of a calibration jig is sampled and coordinates of a projection position of the rotation center axis are calculated from the collected X-ray transmission information. An X-ray source and an X-ray detector arranged opposite to each other, a rotary table arranged therebetween, and at least one axis arranged on the rotary table for mounting or moving or tilting the sample Using the X-ray transmission information collected at every predetermined rotation angle by irradiating X-rays while rotating the rotary table with the sample mounted on the sample table with the sample table mounted thereon, In an X-ray CT apparatus provided with a tomogram reconstruction calculation means for reconstructing a tomogram of a sample along a plane orthogonal to the rotation center axis,
A holding member of a rotation center axis calibration jig composed of a wire made of a material having a high X-ray absorption rate and a holding member made of a material having a low X-ray absorption rate that holds the wire in a straight line on the rotary table, An X-ray CT apparatus comprising a calibration jig mounting mechanism for mounting the wire in a detachable or retractable manner along the rotation center axis in the vicinity of the rotation center axis. An X-ray source and an X-ray detector arranged opposite to each other, a rotation mechanism for rotating a pair of the X-ray source and the X-ray detector around a predetermined rotation center axis, and the X-ray source and the X-ray detection A sample table arranged between the vessels, a sample table arranged on the sample table and equipped with at least one axis drive mechanism for mounting or moving or tilting the sample, and a sample on the sample table Mounted and irradiated with X-rays while rotating the pair of the X-ray source and the X-ray detector, and using the X-ray transmission information collected at every predetermined rotation angle, along a plane orthogonal to the rotation center axis In an X-ray CT apparatus provided with a tomographic image reconstruction means for reconstructing a tomographic image of a sample,
A holding member of a rotation center axis calibration jig composed of a wire made of a material having a high X-ray absorption rate and a holding member made of a material having a low X-ray absorption rate that holds the wire linearly on the sample stage, An X-ray CT apparatus comprising a calibration jig mounting mechanism for mounting the wire in a detachable or retractable manner along the rotation center axis in the vicinity of the rotation center axis.

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