JP2004194946A - X-ray computer tomograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a scanogram of resolution higher than that specific to a detector. <P>SOLUTION: The X-ray computer tomograph is provided with: an X-ray tube 21; an X-ray detector 23 having a plurality of detection elements 41 which have a width W1 in a channel direction and a width W2 in a slice direction and are arrayed two-dimensionally; an X-ray shielding plate 24 which is attachable to and detachable from the X-ray detector and constitutes a checkered pattern with an opening part 49 where an X-ray shielding part 47 having a width W1/2 in the channel direction and a width W2 in the slice direction substantially transmits X-rays; a system control part 11 which generates the X-rays from the X-ray tube while continuously moving a top plate in the slice direction and which makes the X-ray detector to repeatedly read a signal with a prescribed cycle; and a scanogram generation part 31 for generating scanogram data having the resolution of W1/2 in the channel direction based on the output of the X-ray detector. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has a function of reconstructing tomographic image data based on projection data collected from multiple directions related to a subject and generating scanogram data based on projection data collected from a specific direction related to the subject. X-ray computed tomography apparatus.
[0002]
[Prior art]
2. Description of the Related Art X-ray computed tomography apparatuses are rapidly spreading as one of important medical diagnostic apparatuses. In an X-ray computed tomography apparatus, the subject is irradiated with X-rays generated by an X-ray tube. The X-ray transmitted through the subject is detected by each detection element of the X-ray detector. The X-ray detector has a plurality of detection elements arranged in a channel direction. Recently, an X-ray detector (referred to as a multi-slice X-ray detector) having a plurality of detection elements arranged in the slice direction as well as in the channel direction has appeared.
[0003]
Many X-ray computed tomography apparatuses are equipped with a function of capturing scanogram data that approximates a plane transmission image. As is well known, the scanogram data is obtained by periodically sampling the signal readout from the detector while moving the top plate on which the subject is mounted at a constant speed while fixing the X-ray tube at a certain rotation angle. Can be collected. FIG. 7 shows an example of a scanogram. In FIG. 7, the number assigned to each pixel indicates a sampling number. This scanogram is obtained at a resolution equivalent to the resolution Pch inherent to the detection element array, particularly in the channel direction. The resolution in the slice direction is determined by the relationship between the moving speed of the top and the sampling frequency. In FIG. 7, the relationship between the moving speed of the top and the sampling frequency is set so as to match the pitch Psl of the detection element rows. Shows the case.
[0004]
Although the resolution of the scanogram is not high enough for the scanogram itself to withstand interpretation and diagnosis, the scanogram is originally intended for use only as a reference when determining scan conditions such as the scan start position and range. It is collected, and so far scanograms have not been required to have very high resolution.
[0005]
[Patent Document 1]
JP-A-2002-301056
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray computed tomography apparatus capable of generating a scanogram having a resolution higher than the resolution inherent in an X-ray detector and capable of withstanding a diagnosis.
[0007]
[Means for Solving the Problems]
An X-ray computed tomography apparatus according to a first aspect of the present invention has an X-ray tube, an X-ray control unit that generates X-rays from the X-ray tube, a first width in a channel direction, and a slice direction. An X-ray detector having a plurality of detection elements arranged in a two-dimensional manner having a second width; and a top plate for placing a subject between the X-ray tube and the X-ray detector. A bed that is movably supported in the slice direction, and that is detachably attached to the X-ray detector, has a width that is approximately half of the first width in the channel direction, and An X-ray shielding portion having a width substantially equivalent to the second width and an X-ray shielding plate forming a checkered pattern together with an opening portion for substantially transmitting X-rays, and the top plate being continuously moved in the slice direction. X-rays from the X-ray tube The X-ray control unit, a system control unit that controls the X-ray detector and the bed so as to repeatedly read a signal from the X-ray detector at a predetermined cycle, and an output of the X-ray detector. And a scanogram generation unit that generates scanogram data having a resolution of about の of the first width in the channel direction based on the scan data.
An X-ray computed tomography apparatus according to a second aspect of the present invention has an X-ray tube, an X-ray control unit that generates X-rays from the X-ray tube, a first width in a channel direction, and a slice direction. An X-ray detector having a plurality of detection elements arranged in a two-dimensional manner having a second width; and a top plate for placing a subject between the X-ray tube and the X-ray detector. A bed that is movably supported in the slice direction, and is detachably attached to the X-ray detector, where N is an integer of 3 or more, and the first width is approximately (N−1) / An X-ray shielding portion having a length of N and having a width substantially equivalent to the first width in the slice direction has a width of about 1 / N of the first width in the channel direction; Has a width substantially equivalent to the second width in the slice direction The openings that substantially pass X-rays and the openings are alternately arranged in the channel direction, and the positions of the openings in the channel direction are shifted by about 1 / N of the first width between columns in the slice direction. While continuously moving the X-ray shielding plate and the top plate in the slice direction, an X-ray is generated from the X-ray tube, and a signal is repeatedly read from the X-ray detector at a predetermined cycle. A system controller that controls the X-ray controller, the X-ray detector, and the couch; and a resolution of about 1 / N of the first width in the channel direction based on an output of the X-ray detector. And a scanogram generation unit that generates scanogram data having the following.
An X-ray computed tomography apparatus according to a third aspect of the present invention provides an X-ray detector having an X-ray tube, a plurality of detection elements two-dimensionally arranged in a channel direction and a slice direction, and the X-ray detection device. An X-ray shielding plate which is detachable from the detector and is configured to partially shield each of the detection elements, and based on an output of the detection element, a detection element array of the X-ray detector. A scanogram generation unit that generates scanogram data having a higher resolution than the inherent resolution.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of an X-ray computed tomography apparatus according to the present invention will be described with reference to the drawings. The X-ray computed tomography apparatus has a rotation / rotation type in which an X-ray tube and an X-ray detector rotate as one body around a subject, and a number of detection elements arranged in a ring shape. There are various types such as a fixed / rotating type in which only the tube rotates around the subject, and the present invention is applicable to any type. Here, the rotation / rotation type which occupies the mainstream at present is described. Further, in order to reconstruct one slice of tomographic image data, projection data of about 360 ° around one circumference of the subject and projection data of 180 ° + view angle are required even in the half scan method. . The present invention is applicable to any reconstruction method. Here, the half scan method will be described as an example. The mechanism of converting incident X-rays into electric charges is an indirect conversion type in which X-rays are converted into light by a phosphor such as a scintillator and the light is converted into electric charges by a photoelectric conversion element such as a photodiode. The mainstream is the generation of an electron-hole pair in a semiconductor and its transfer to an electrode, that is, a direct conversion type utilizing a photoconductive phenomenon. As the X-ray detecting element, any of those methods may be adopted, but here, the former indirect conversion type will be described. In recent years, a so-called multi-tube X-ray computed tomography apparatus in which a plurality of pairs of an X-ray tube and an X-ray detector are mounted on a rotating ring has been commercialized, and peripheral technology has been developed. I have. The present invention is applicable to both conventional single-tube X-ray computed tomography apparatuses and multi-tube X-ray computed tomography apparatuses. Here, the description will be made as a single tube type.
[0009]
Further, the tomographic image is a sectional display of a tissue having a certain thickness, and the thickness of the tissue cross section is referred to as a slice thickness. The X-rays radiate from the X-ray tube focal point, pass through the subject, and reach the X-ray detector. Therefore, the thickness of the X-rays increases as the distance from the focal point of the X-ray tube increases. Conventionally, an X-ray on a reference plane defined by a line connecting the focal point of the X-ray tube and the center of the detector (generally called an imaging center line) and a rotation center axis intersecting at the origin. The thickness is defined as the slice thickness. Here, according to a custom, the thickness of the X-ray on the reference plane is referred to as a slice thickness. The same can be said for the width of the detection element in the channel direction and the width in the slice direction.When the width of the detection element in the slice direction is used, not the actual width but the actual width on the reference plane here. It is defined as a converted value, and similarly, the width of the detection element in the channel direction is defined as a converted value on a reference plane. Similarly, the expression “resolution of scanogram” is similarly defined as a converted value on a reference plane. Here, the resolution of the scanogram is defined as a distance between center points between adjacent pixels of the scanogram data, and the defined distance is given as a distance on a reference plane.
[0010]
FIG. 1 is a block diagram showing a configuration of a computer tomography apparatus according to the present embodiment. The ring-shaped gantry rotating unit 25 is supported by a gantry frame (not shown) so as to be rotatable around a rotation center axis (Z axis). A motor (not shown) that generates power for rotating the gantry rotating unit 25 is installed on the gantry frame. The rotation prime mover receives power supply from the gantry bed control unit 13 to generate power. The gantry rotating unit 2 has a cone beam X-ray tube 21 and a multi-slice X-ray detector 23 mounted thereon. The X-ray detector 23 faces the X-ray tube 21 via the subject placed on the couch top 22. The high voltage generator 19 applies a high voltage between the cathode of the X-ray tube 21 and the rotating anode under the control of the X-ray controller 17, and applies a heating current to the cathode filament of the X-ray tube 21. Supply. Thermionic electrons emitted from the heated filament are accelerated by the high voltage and collide with the target of the rotating anode. Thereby, X-rays are generated. The generated X-ray is irradiated to the subject while being restricted to an arbitrary thickness in the slice direction by the X-ray aperture 20. Here, in order to enable continuous rotation, the X-ray tube 21 is electrically connected to the high voltage generator 19 via a slip ring (not shown).
[0011]
The bed moving unit 15 has a motor that generates power for moving the table 22 in the Z-axis direction. The prime mover generates power by receiving power supply from the gantry bed control unit 13. The gantry bed control unit 13 performs an operation for scanning (multidirectional data collection) and scanogram imaging (one-way data collection) under the control of the system control unit 11 together with the X-ray control device 17.
[0012]
A data acquisition unit (DAS) 27 is connected to the X-ray detector 23. The data collection unit 27 includes an integrator that integrates a current or voltage signal output from the X-ray detector 23, an amplifier that amplifies an output signal of the integrator, and an analog that converts an output signal of the preamplifier into a digital signal. -A digital converter is provided for the number of channels. A data storage unit 29 for storing data output from the data collection unit 27 is connected to the data collection unit 27. Note that the data output from the data collection unit 27 is generally called raw data. Typically, raw data undergoes various pre-processing such as sensitivity uniformity correction between channels. Raw data that has been preprocessed is generally referred to as projection data. The data storage unit 29 includes a processing unit for performing preprocessing on the raw data from the data collection unit 27 in a data input stage, and stores the data as projection data. The data storage unit 29 is connected to a reconstruction calculation unit 32 for reconstructing tomographic image data based on the projection data, and a scanogram generation unit 31 for generating scanogram data based on the projection data. A display unit 33 for displaying tomographic image data and scanogram data is connected to the reconstruction operation unit 32 and the scanogram generation unit 31.
[0013]
An input unit 35 including input devices such as a keyboard and a pointing device is connected to the system control unit 11. Scan conditions, scanogram photographing conditions, and the like are input to the system control unit 11 from the operator via the input unit 35. The system control unit 11 performs scan according to the scan conditions, reconstructs and displays the tomographic image data, and executes scanogram photography according to the scanogram photography conditions to generate and display scanogram data. The X-ray controller 17, the couch controller 13, the data acquisition unit 27, the data storage unit 29, the image reconstruction unit 32, the scanogram generation unit 31, and the display unit 33 are comprehensively controlled.
[0014]
The X-ray shielding plate 22 is detachably attached to the multi-slice type X-ray detector 23. The X-ray shielding plate 22 is used during scanogram imaging, and particularly when an operator or the like determines that it is necessary to perform signal detection at a higher resolution than the resolution inherent to the X-ray detector 23 in the channel direction. It is attached to the X-ray detector 23 by the hand of a person or the like. The X-ray detector 23 has a function of realizing signal detection with a higher resolution than the X-ray detector 23 in the channel direction.
[0015]
FIG. 2A is a plan view of the multi-slice type X-ray detector 23. The X-ray detector 23 has a plurality of detection elements 41 arranged two-dimensionally in two directions, a channel direction (X) and a slice direction (Z). In other words, a plurality of rows of detection elements arranged in a line along the channel direction are arranged in parallel along the slice direction.
[0016]
Each detection element 41 has a width of “W1” in the channel direction and has a width of “W2” in the slice direction. The plurality of detection elements 41 are densely arranged at a pitch (distance between center points) Pch substantially equivalent to the width “W1” in the channel direction. The pitch of the element array in the channel direction is called an element pitch Pch. Similarly, also in the slice direction, they are densely arranged at a pitch Psl substantially equivalent to the width “W2”. The pitch of the element array in the slice direction is referred to as an element row pitch Psl. The resolution inherent in the element array of the X-ray detector 23 is defined by the element pitch Pch in the channel direction and by the element row pitch Psl in the slice direction.
[0017]
As shown in FIG. 2 (b), the X-ray shielding plate 22 completely shields the detection elements 41 constituting the peripheral rows other than the two central rows from the X-rays, and the detection elements constituting the two central rows. Each of the 41 is partially shielded and the shield is configured to shift in the channel direction between columns. The X-ray shielding plate 22 is formed by, for example, press-cutting one shielding plate so that each component constituting the X-ray shielding plate 22, that is, the shielding portions 45 and 47 and the opening 49 are formed in an arrangement described later. The edge shielding portion 45 is provided to shield all the detection elements 41 constituting the edge rows other than the two central rows. The partial shielding portion 47 is provided to partially shield each of the detection elements 41 constituting the two central rows. The opening 49 is provided to partially open each of the detection elements 41 constituting the two central rows. The opening 49 may be opened without any substance, that is, provided as a gap between adjacent partial shields 47, or as shown in FIG. 3, substantially transparent to X-rays. It may be composed of an entity made of a material or an entity made of a material having a very low X-ray absorptivity.
[0018]
The partial shielding portion 47 has a rectangular shape, has a width (second width) substantially the same as the width W2 of the detection element 41 in the slice direction (Z), and has the detection element 41 in the channel direction (X). Has a width (W1 / 2) (first width) that is substantially the same as 1/2 of the width W1. The opening 49 has the same rectangular shape as the partial shielding portion 47, has a width substantially equal to the width W2 of the detection element 41 in the slice direction (Z), and has the same width in the channel direction (X). Has a width (W1 / 2) substantially equal to 1/2 of the width W1.
[0019]
The partial shields 47 are discretely arranged at the same pitch as the element pitch Pck of the detection element 41 in the channel direction. An opening 49 is formed in a gap between the adjacent partial shields 47. The position of the partial shielding portion 47 in the channel direction is shifted by 列 of the element pitch pch of the detecting element 41 between the columns.
[0020]
As described above, with respect to the two central rows, the partial shielding portions 47 are alternately arranged with the openings 49 along the two directions of the slice direction and the channel direction, and the positions in the channel direction are shifted between the rows. As a result, a checkered pattern is formed as a whole.
[0021]
When the X-ray shielding plate 22 is mounted on the X-ray detector 23, the alignment is performed by the alignment holes 51 and 53. By this alignment, the pair of the adjacent partial shield 47 and the opening 49 is aligned with respect to each of the detection elements 41 forming the two central rows. Regarding one of the two central columns, the right half of each detection element 41 is shielded from X-rays by the partial shielding part 47, and the left half is opened, so that the X-rays transmitted through the subject can be detected by each detection element 41. Detected in left half. With respect to the other two rows of the central two rows, the left half of each detecting element 41 is shielded by the partial shielding part 47 and the right half is opened in a state shifted from the one row by Pch / 2 in the channel direction. As a result, the X-ray transmitted through the subject is detected by the right half of the detection element 41.
[0022]
Next, the operation of scanogram imaging will be described. In scanogram imaging, when an operator or the like desires a high-resolution scanogram, often when the scanogram is also used for diagnosis, the operator or the like attaches the X-ray shield plate 22 to the X-ray detector 23. As a result, the detecting elements 41 constituting the peripheral rows other than the central two rows are shielded, and the right half of the detecting elements 41 constituting one of the central two rows is shielded by the partial shielding portion 47, and the left half thereof Is opened. The left half of the detection element 41 constituting the other row is shielded by the partial shielding part 47, and the right half is opened.
[0023]
In addition, scanogram imaging conditions are input via the input unit 35. The scanogram imaging conditions include general conditions such as an imaging range and X-ray intensity, as well as the presence / absence of the X-ray shield plate 22 (necessity of a high-resolution scanogram) and the condition relating to the resolution in the slice direction. included. As shown in FIG. 4, a sampling cycle accompanying reading of signals from the detection elements of the X-ray detector 23 by the data collection unit 27 is shown. Assuming that the sampling frequency is fs, sampling is repeated at a cycle of the reciprocal (1 / fs). The top plate moving speed S, element row pitch Psl, and coefficient n (n is a natural number) for determining the resolution with respect to the sampling cycle (1 / fs) are given by the following relationships.
(1 / fs) × S = Psl / n
This relational expression represents the number of samplings (n) performed while the top plate 22 moves the element row pitch Psl. When the number of samplings (n) is high, the resolution in the slice direction is high. Conversely, when the number of samplings (n) is low, the resolution in the slice direction is low, and the number of samplings (n) is a minimum value of “1”. At some point, the resolution in the slice direction is equivalent to the element row pitch Psl.
[0024]
The number of times of sampling (n) may be actually input as a numerical value, or it is practical to set the resolution in the slice direction to such a degree as an option such as “high resolution”, “medium resolution”, or “low resolution”. It is thought that it is. When "high resolution" is selected, the number of samplings (n) is set to, for example, "3" by the system control unit 11, and similarly, "2" for "medium resolution" and "1" for "low resolution". Is set to
[0025]
In the system control unit 11, at least one of the sampling frequency fs and the moving speed S of the tabletop 22 is set so as to satisfy the above relational expression under the set number of samplings (n). Actually, the moving speed S of the tabletop 22 is selected with the sampling frequency fs fixed at a specified value.
[0026]
After the completion of the condition setting, the scanogram photographing is actually started. First, the X-ray diaphragm 20 adjusts the width of the slit to the width of the two central rows. The top 22 is moved in one direction (either (+) or (-) of the Z axis (slice direction)) at the set moving speed S together with the subject. X-rays are continuously generated and irradiated to the subject during a period in which the tabletop 22 moves within a preset imaging range. Then, the X-ray transmitted through the subject is detected by the X-ray detector 23, and the signal charge of each detection element is repeatedly read by the data collection unit 27 at a predetermined sampling cycle (1 / fs). The read projection data is stored in the data storage unit 29 in association with the column number, the channel number, and the sampling number. After the end of the scanogram imaging, the scanogram generation unit 31 rearranges the projection data stored in the data storage unit 29 under the control of the system control unit 11 to generate scanogram data.
[0027]
FIG. 5 schematically shows the pixel arrangement of the scanogram data. The number assigned to each pixel is a sampling number indicating the order of sampling. Pixels have a pitch of (Psl / n) set in advance in the slice direction, and 1 in the actual element pitch Psl of the detection element 41 in the channel direction according to the arrangement of the openings 49 in the X-ray shield 22. / 2 pitch. For this pixel distribution, projection data is given to pixels at positions corresponding to the sampling number, column number, and channel number. As a result, a high-resolution scanogram having a resolution of (Psl / n) in the slice direction and a resolution (Psl / 2) higher than the actual element pitch in the channel direction can be generated.
[0028]
In the above description, an example has been described in which scanogram data is generated with a resolution as high as 1/2 of the actual element pitch in the channel direction. However, it is also possible to generate scanogram data at a higher resolution of 1 / N (N is an integer of 3 or more) of the actual element pitch Pch in the channel direction.
[0029]
FIG. 6A is a plan view of an X-ray shielding plate used to generate scanogram data with a high resolution of 1/4 of the actual element pitch in the channel direction. This X-ray shield plate completely shields the detection elements 41 constituting the rows at the edges other than the four central rows from X-rays, and partially shields each of the detection elements 41 constituting the four central rows. Is configured. The partial shielding portion 57 has a width substantially the same as the width W2 of the detection element 41 in the slice direction (Z), and a width substantially the same as ／ of the width W1 of the detection element 41 in the channel direction (X). ((3 · W1) / 4). The opening 55 has substantially the same width as the width W2 of the detection element 41 in the slice direction (Z), and has substantially the same width (（) as the width W1 of the detection element 41 in the channel direction (X). W1 / 4).
[0030]
The partial shields 57 are discretely arranged at the same pitch as the element row pitch Psl of the detection elements 41 in the channel direction, and an opening 55 is provided between adjacent partial shields 57. Further, the position of the partial shielding portion 57 in the channel direction is shifted by 列 of the element pitch Pch of the detection element 41 between the rows.
[0031]
By performing scanogram imaging using such an X-ray shielding plate, it has a resolution of (Psl / n) in the slice direction and a resolution (Psl / 4) higher than the actual element pitch in the channel direction. A scanogram can be generated.
[0032]
FIG. 6B is a plan view of an X-ray shielding plate used when generating scanogram data with a resolution of 1/3 of the actual element pitch in the channel direction. This X-ray shielding plate completely shields the detection elements 41 constituting the rows of the edges other than the three central rows from X-rays, and partially shields each of the detection elements 41 constituting the three central rows. Is configured. The partial shielding portion 61 has a width substantially the same as the width W2 of the detection element 41 in the slice direction (Z), and a width substantially the same as ／ of the width W1 of the detection element 41 in the channel direction (X). ((2 · W1) / 3). The opening 59 has a width substantially the same as the width W2 of the detection element 41 in the slice direction (Z), and a width (同一) substantially the same as １ ／ of the width W1 of the detection element 41 in the channel direction (X). W1 / 3).
[0033]
The partial shields 61 are discretely arranged at the same pitch as the element row pitch Psl of the detection elements 41 in the channel direction, and an opening 59 is formed in a gap between the adjacent partial shields 61. The position of the partial shield 61 in the channel direction is shifted by １ ／ of the element pitch Pch of the detection element 41 between the rows.
[0034]
By performing scanogram imaging using such an X-ray shielding plate, a resolution of (Psl / n) is obtained in the slice direction and a resolution (Psl / 3) higher than the actual element pitch is obtained in the channel direction. A scanogram with the resolution can be generated.
[0035]
The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention at the stage of implementation. Furthermore, the above-described embodiment includes various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, some components may be deleted from all the components shown in the embodiment.
[0036]
【The invention's effect】
According to the present invention, a scanogram can be generated with a higher resolution than the resolution inherent in the detector.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an X-ray computed tomography apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view of the X-ray detector and the X-ray shielding plate of FIG.
FIG. 3 is a plan view of another X-ray shielding plate in FIG. 2;
FIG. 4 is a time chart illustrating data sampling by the data collection unit in FIG. 1;
FIG. 5 is a diagram showing the resolution of scanogram data generated by a scanogram generation unit in FIG. 1;
FIG. 6 is a plan view of an X-ray shield plate of still another high-resolution specification in FIG. 2;
FIG. 7 is a diagram showing the resolution of conventional scanogram data.
[Explanation of symbols]
11 ... System control unit
13: gantry bed control unit,
15: bed moving unit,
17 ... X-ray control device,
19 ... High voltage generator,
20 ... X-ray aperture,
21: cone beam X-ray tube,
22 ... top plate,
23 multi-slice X-ray detector,
24 X-ray shielding plate,
25 ... gantry rotating part,
27… Data collection unit,
29 ... data storage unit,
31: scanogram generation unit
32 ... reconstruction operation unit
33 ... Display unit.

Claims (3)

An X-ray tube,
An X-ray control unit that generates X-rays from the X-ray tube;
An X-ray detector having a plurality of two-dimensionally arranged detection elements having a first width in the channel direction and a second width in the slice direction;
A bed for supporting a table for mounting a subject between the X-ray tube and the X-ray detector so as to be movable in the slice direction;
It is detachable with respect to the X-ray detector, has a width of about half of the first width in the channel direction, and has a width substantially equivalent to the second width in the slice direction. An X-ray shielding plate, wherein the X-ray shielding portion forms a checkered pattern together with an opening portion through which X-rays substantially pass;
While continuously moving the top plate in the slice direction, the X-ray control unit so as to generate X-rays from the X-ray tube and repeatedly read a signal from the X-ray detector at a predetermined cycle. A system control unit that controls the X-ray detector and the bed;
A scanogram generation unit that generates scanogram data having a resolution of about 1/2 of the first width in the channel direction based on an output of the X-ray detector. Computer tomography equipment. An X-ray tube,
An X-ray control unit that generates X-rays from the X-ray tube;
An X-ray detector having a plurality of two-dimensionally arranged detection elements having a first width in the channel direction and a second width in the slice direction;
A bed for supporting a table for mounting a subject between the X-ray tube and the X-ray detector so as to be movable in the slice direction;
It is detachable with respect to the X-ray detector, and has a length of approximately (N-1) / N of the first width in the channel direction, where N is an integer of 3 or more, and the slice direction An X-ray shielding portion having a width substantially equivalent to the first width has a width of about 1 / N of the first width in the channel direction, and has a width substantially equal to the second width in the slice direction. Opening portions for substantially transmitting X-rays having an equivalent width are alternately arranged in the channel direction, and the positions of the opening portions in the channel direction are approximately 1/1/1 of the first width between columns in the slice direction. An X-ray shielding plate shifted by N,
While continuously moving the top plate in the slice direction, the X-ray control unit so as to generate X-rays from the X-ray tube and repeatedly read a signal from the X-ray detector at a predetermined cycle. A system control unit that controls the X-ray detector and the bed;
A scanogram generation unit that generates scanogram data having a resolution of about 1 / N of the first width in the channel direction based on the output of the X-ray detector. Computer tomography equipment. An X-ray tube,
An X-ray detector having a plurality of detection elements two-dimensionally arranged in a channel direction and a slice direction;
An X-ray shielding plate detachable from the X-ray detector and configured to partially shield each of the detection elements;
An X-ray computer, comprising: a scanogram generation unit configured to generate scanogram data having a higher resolution than a resolution specific to the detection element array of the X-ray detector based on an output of the detection element. Tomography equipment.

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