JPH08243098A - X-ray ct equipment - Google Patents

Abstract

PURPOSE: To provide X-ray CT equipment capable of obtaining a good tomography image inexpensively, by high-precisely and simply arranging a channel direction collimator and a detector element array of a solid detector. CONSTITUTION: This X-ray CT equipment, which is to obtain an examinee's body tomography image by guiding X-ray from an X-ray tube to a solid detector controlling its width by a collimator 31 in the slice direction mounted in an arc shape in the incoming side of the detector container 30, is constituted so as to separate a collimator in the channel direction arranging a plurality of grid plates G with an equal angle into a plurality of blocks. Those are assembled based on a step part formed on the lower end of the arc collimator in the slice direction, A detector element array is arranged in a polygon shape along the arc with the center on the focus of the plural X-ray tubes in the detector container 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus for obtaining a tomographic image of a subject such as a human body by X-rays, and more particularly to improving the structure of an X-ray detector of the X-ray CT apparatus.

[0002]

2. Description of the Related Art In an X-ray CT apparatus that obtains a tomographic image of a human body such as a patient by X-rays, the X-rays emitted from a source of X-rays and passing through a subject are detected by an X-ray detection element at an incident portion.
That is, the X-ray detection element of such an apparatus measures the attenuation of X-rays due to the subject portion existing on the line (measurement path) connecting the focal point of the X-ray tube that is the X-ray generation source and the center of the detection element. However, when scattered X-rays from other parts of the subject are incident, however, this measurement causes an error. That is, due to the incidence of scattered X-rays, the output of the detection element becomes larger than the actual value,
The attenuation of the subject on the measurement path is measured to be apparently small, which causes an error in the measurement.

When such an error increases, the resolution of the CT image (cross-sectional image) reconstructed using these measurement data will decrease. In particular, deterioration of low contrast resolution called density resolution becomes a problem. In addition, as a cause of such an error, clinically, a CT value inside the rib called a rib artifact sinks, which causes a black area to appear on the image, or the liver. The CT value inside may vary depending on the place.

In order to eliminate the adverse effects of such scattered X-rays, conventionally, in an ionization chamber detector, as shown in FIG. 9 attached, a large number of high-voltage electrode plates are arranged in parallel with the line connecting the X-ray tube focal point and the incident portion. A structure in which is arranged is proposed. In the detector having such a structure, the high-voltage electrode plate has a grid effect to some extent, and therefore, the sensitivity to scattered X-rays obliquely incident is considerably lower than the sensitivity to X-rays incident from the direction of the X-ray tube focus. It becomes possible to do.

On the other hand, in the solid-state detector as shown in FIG. 10 in which a so-called scintillator partitioned by a partition plate and a photoelectric conversion element composed of a photodiode are combined, there is no grid effect as described above. Therefore, it is not possible to eliminate the adverse effect of scattered X-rays. This is because, as is clear from the figure, when scattered X-rays are incident from an oblique direction, the channel width becomes narrower when the detector is viewed obliquely than when viewed from the front. However, there is not much difference between the sensitivity to X-rays incident from the direction of the X-ray tube focus and the sensitivity to scattered X-rays obliquely incident. Therefore, even with respect to scattered X-rays at a level that does not cause much problem as an image artifact in the ionization chamber detector, such solid-state detector often causes deterioration in image quality.

Conventionally, the above-mentioned problems in such a solid-state detector can be solved by disposing a collimator in the channel direction having the above-mentioned grid effect at the incident portion of the solid-state detector. It is already known from US Pat. No. 4,338,521. That is, the detector known from this US patent is
Prepare a detector element module that combines a scintillator, a photodiode (or a photomultiplier), a printed wiring board, a signal extraction connector, a channel direction collimator, and the like, and place multiple detector element modules inside the detector container. It has a structure of lining up. With the detection element having such a structure, the alignment between the solid-state detection element (that is, the scintillator and the photodiode) and the channel direction collimator can be accurately performed, and further, when a defective channel occurs, it is easy to replace the module unit. The advantages such as possible are raised.

However, in this conventional technique, since the channel direction collimator is also divided into the element modules, the number of parts increases, which increases the cost, and the module is arranged in the detector container. Therefore, it is necessary to align the number of modules when manufacturing the detector. Therefore, a large number of so-called positioning pins and holes for aligning and fixing the module must be formed in the module holding portion on the side (wall) surface of the detector container with high precision. In addition, there is a problem that it is necessary to individually arrange and fix these many modules while performing highly accurate alignment with respect to the X-ray tube focal point and the collimator in the slice direction.

[0008]

As described above, according to the above-mentioned conventional technique, in particular, in order to remove the adverse effect of scattered X-rays, it is possible to arrange the collimator in the channel direction having the grid effect in the solid-state detector. Although already proposed, however, a channel-direction collimator having such a grid effect together with a solid-state detector,
A specific structure for highly accurate and easy placement and fixing has not been proposed yet.

Generally, in the X-ray detecting element of the solid-state detector, in order to prevent light emission or scattering in the scintillator due to incident X-rays from entering the adjacent channels and causing crosstalk, the space between the detecting elements is increased. It has a structure partitioned by partition walls. The boundary portion of the detection element partitioned by the partition plate is structurally insensitive to the incident X-ray. On the other hand, when the collimator in the channel direction is combined with the solid-state detection element, the incident X-rays are absorbed by the collimator plate in the channel direction and do not reach the rear side. Therefore, considering the utilization efficiency of incident X-rays, this channel direction collimator plate is
It is desirable to arrange it at the boundary of the detection element where the detection element is not sensitive, and this channel direction collimator is
It is necessary to accurately align the pitch of the line detection elements over all channels.

On the other hand, by manufacturing such a channel-direction collimator plate as an integrated channel-direction collimator over all channels, it is possible to manufacture an object with high positional accuracy in all channels. However, in the process of assembly. However, there is a problem in that even if a part of the collimator is defective, and a channel with poor accuracy occurs, the entire collimator becomes defective.

Further, in the X-ray detector for a CT apparatus having a structure having an arc-shaped slice direction collimator to which the present invention is applied, in order to fix the above-mentioned channel direction collimator plate, a groove or the like is formed in the slice direction collimator. Although it is necessary to process on the arc-shaped inner peripheral surface of the above, as described above, when all channels are made as an integrated body, the size of the workpiece to be processed and the rotation angle at the time of processing become large. There is an inconvenience that it becomes difficult to secure the processing accuracy.

Alternatively, in the method in which the channel-direction collimator is not a single body but is divided into several blocks and is configured by a plurality of blocks, as described above, the processing of the collimator parts can be performed relatively easily and accurately. However, each collimator block must be placed exactly on an arc centered on the X-ray tube focus, and the relative position and angle with the adjacent collimator block and the alignment with the X-ray detection element must be adjusted. In addition, since the characteristics of the detector depend on the accuracy of this alignment, highly accurate registration must be performed. Therefore, conventionally, in order to perform this highly accurate alignment, for example, an alignment jig for aligning each collimator block at a predetermined position according to the outer shape of the channel direction collimator has been used. It took a lot of time to set jigs.

Further, in the solid-state detector, a plurality of detection elements in which a scintillator and a photoelectric conversion element are combined are arranged on a substrate to form a multi-channel X-ray detection element array. They are arranged in a polygonal shape centered on the focal point of the X-ray tube. Therefore, if a large number of grid plates constituting the channel direction collimator are arranged so as to be completely aligned with the arrangement of the detection elements arranged in a polygonal shape, the structure must be complicated.

On the other hand, by arranging the grid plates of the channel-direction collimator at an equal angular pitch, the structure of the channel-direction collimator can be simplified. However, in the X-ray detector array, the X-ray detector array is between the detectors. Since the detection element pitches are evenly spaced in order to reduce variations in characteristics, if this is combined with a grid plate arranged at an equal angular pitch, the detection device and grid plate, that is, the channel position will be It shifts a little, though. As described above, the positional deviation between the grid plate and the detection element causes a deviation in the detection characteristics of the detector. In particular, this deviation results in a periodic deviation in the characteristics of each detection element array. Specifically,
This causes a ring-shaped artifact on the obtained tomographic image.

Therefore, in the present invention, in view of the problems in the prior art as described above, that is, in the solid-state detector, a collimator in the channel direction having a plurality of grid plates is used together with an X-ray detection element constituting the solid-state detector. It is an object of the present invention to provide a structure for arranging and fixing with high accuracy and a simple structure, and thus to provide an X-ray detector for a CT device that can be assembled inexpensively as a whole device. .

[0016]

In order to achieve the above-mentioned object, first of all, an X-ray CT apparatus proposed by the present invention comprises an X-ray generating source for emitting X-rays and an X-ray detecting means inside. An arc-shaped detector container arranged in an arc shape with the X-ray generation source as a center, and X-rays emitted from the X-ray generation source are provided in an arc shape on the incident surface side of the arc-shaped detector container. An X-ray CT apparatus for obtaining a tomographic image of a subject by limiting the width of the slice through a collimator in the slice direction to obtain a tomographic image of the subject, and the arc-shaped slice of the detector container. A plurality of grid plates are provided between the directional collimator and the X-ray detecting means arranged in the arc shape.
In the arrangement in which the collimators in the channel direction arranged at equal angles to the line generation source are arranged, the channel direction collimator is divided into a plurality of blocks in the channel direction to form blocks, and the blocks of the plurality of channel direction collimators are formed. The reference line formed at the end of the arc-shaped slice direction collimator on the X-ray detecting means side is incorporated as a reference.

Further, according to the present invention, the above-mentioned X-ray CT
In the apparatus, the X-ray detection means comprises X-ray detection elements formed by stacking a light conversion element and a scintillator, which are equally spaced by a partition plate, and these detection elements are arranged on the substrate at a plurality of equal intervals. The X-ray detection element array configured by
In the detector container, a plurality of them are arranged in a polygonal shape along an arc centered on the X-ray generation source, and further, a plate thickness of a grid plate constituting the channel direction collimator is at least It has been proposed that the thickness of the partition plate is larger than the thickness of the partition plate arranged between the detection elements of the X-ray detection element array formed on the substrate.

That is, as will be apparent from the embodiments proposed below according to the present invention, with respect to the slice direction collimator, a channel wider than the detector array is provided in the X-ray incident portion of the X-ray detector. A plurality of blocks in which the direction collimator block is fixed to the grid block holding plate (this holding plate also serves as the slice direction collimator) is formed, and these blocks are formed in an arc shape on the X-ray detection means side of the arc shape slice direction collimator. The formed step is incorporated as a reference, and regarding the X-ray detection element array, this is arranged in a polygonal shape inside the detector container, and as a result, all channels are detected as a channel direction collimator assembly with an integrated structure. It is assembled in a container and put together as a detector with a channel direction collimator.

[0019]

In the incident portion of the X-ray detecting element, the scattered rays incident obliquely with respect to the slice direction are blocked to some extent, and the end of the X-ray detecting element in which the sensitivity variation between channels is large compared to the central portion. A slice-direction collimator is provided to control the X-rays incident on the section. Therefore,
With the structure in which the channel-direction collimator block is incorporated and integrated into the slice-direction collimator provided at the incident part of the X-ray detection element, the mutual positions and angles of the channel-direction collimators can be easily and accurately adjusted. .

That is, by assembling the detector by a method of arranging a plurality of channel-direction collimator blocks with reference to a predetermined reference line position of the slice-direction collimator, the channel can be processed without using a large and accurate processing machine. The components of the directional collimator can be manufactured with high accuracy, and the relative positional relationship between the channel directional collimator blocks can be easily and accurately matched.
As a result, most of the scattered X-rays incident on the X-ray detection element can be removed, and a good X-ray detector with uniform channel characteristics can be created, and high diagnostic ability without artifacts can be obtained. It becomes possible to obtain a CT image.

Further, by arranging the X-ray detection element array along an arc centered on the X-ray generation source, the light conversion elements are arranged on the plane of the substrate without complicating the structure of the channel direction collimator. It becomes possible to relatively easily position an X-ray detection element array formed by separating a plurality of or scintillators by a partition plate at equal intervals,
Furthermore, by increasing the plate thickness of the grid plate,
Even for a channel direction collimator that can be produced relatively easily by arranging grid plates at equal angles, by considering the plate thickness of the grid plates, periodic characteristic deviation does not occur, By using a grid with a relatively simple structure, obliquely scattered rays can be removed and the occurrence of artifacts can be suppressed.

That is, according to the above arrangement of the detecting element arrays arranged in a polygonal shape, the end channels of the detecting element array are seen slightly obliquely when viewed from the X-ray tube focus, and the opening angle of the channels is the central channel. It becomes slightly smaller than that of the above, and the element angle pitch also becomes smaller toward the end channel of the detection element array. Especially when combined with a collimator with an equiangular pitch, the deviation between the channels of the detection element and the grid becomes the largest in the end channel of the detection element array. So, the thickness of this grid plate,
In consideration of this maximum deviation, by making the partition plate thicker than the thickness of the partition plate used in the detection element array, it is possible to eliminate the characteristic deviation due to the channel position deviation between the grid and the detection element.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 shows a principle structure of an X-ray CT apparatus which is an embodiment of the present invention, that is, an X-ray generation source shown by reference numeral 10 in the drawing, that is, an X-ray tube radiated. The X-rays that have passed through the subject 20, such as a patient, are detected in a detector container 30 having an X-ray detector therein. Then, using the data measured by this, a predetermined image processing operation is performed by an electronic calculator (not shown) or the like to reconstruct a CT image that is a cross-sectional image of the subject.
As is clear from this figure, the detector container 30
The detection element is formed in a circular arc shape with the focus position of the X-ray tube 10 as the center, and the detection element as a whole is housed in this container. The printed wiring board supporting the substrate and the slice direction collimator are
Placed inside and fixed. A large number of X-ray detectors are arranged in the lateral direction (indicated by arrow C) on the paper surface of this figure, which is called a channel direction, and the front and back direction (indicated by a mark S) of the paper surface is photographed. The so-called slice direction, which is the width of the cross section of the subject, is shown.

Next, FIG. 1 shows a sectional structure of the detector container 30. As is clear from this figure,
The X-rays that have passed through the subject and have gone from the top to the bottom of the drawing pass through the detector entrance E having a width W in the slice direction formed on the inner peripheral surface (upper side surface of the drawing) of the detector container 30. As described above, the light enters the scintillator 41 that constitutes the detection element. The scintillator 41 emits light according to the intensity of the incident X-ray,
The light is received by a photodiode 42 arranged in contact with the lower side of the scintillator 41 in a layered manner, and converted into an electric signal (current) here. This converted signal current is
It passes through the printed wiring board 43, the connector 44, and further the signal cable 45, and is sent to an amplifier circuit (not shown) and the like connected in the subsequent stage.

The detector entrance portion E having the width W is formed by a pair of slice-direction collimators 31 and 31 arranged on the inner peripheral surface of the detector container 30 so as to face each other. FIG. 3 shows the outer shape of one of the slice-direction collimators 31, which has a substantially “L” -shaped cross section and which is also circular along the inner peripheral surface of the detector container 30. It is curved and formed in an arc shape. Considering the X-ray shielding efficiency, these slice direction collimators 31 and 31 are effectively formed using a material having a high X-ray absorption coefficient, such as tungsten or molybdenum.

On the X-ray incident side of the scintillator 41, a channel-direction collimator 32 is installed following the slice-direction collimators 31 and 31, which scatters in the subject 20. It has a structure that shields scattered X-rays that obliquely enter the detection element. The channel-direction collimator 32 is composed of a plurality of blocks. The plurality of blocks are stepped portions 33, 3 formed by notches provided on the detection element side of the pair of slice-direction collimators 31, 31.
It is structured such that it is positioned so as to be fitted into the connector 3 and assembled, and then fixed by screws 34, 34 and the like. Further, reference numerals 35 and 35 in the drawing denote holding members for arranging and fixing the channel direction collimator 32 at a predetermined position.

The structure of one block B of this channel direction collimator 32 is shown in the attached FIG. In the figure, a pair of holding members 35 and 3 are arranged facing each other with a width W in the slice direction of the detector entrance portion 31.
5 is formed of a material suitable for precision processing such as metal or ceramic material, and a plurality of grooves 36, 36 ... Are formed side by side at equal intervals on the inner surface of each.
The detector entrance portion 31 is formed by these grooves 36, 36 ...
Width W '(W' = W + α that is wider than the width W in the slice direction of
> W) grooves are formed, and a plate-like channel-direction collimator plate (grid plate) G is inserted into these grooves 36, 36 ... And side walls of the grooves 36, 36 ... Of the holding members 35, 35. It is fixedly adhered to by an adhesive or the like.

That is, the channel direction collimator 32
Is configured by dividing one detector into a plurality of blocks. Then, the respective blocks constituting the channel direction collimator 32 are fixed by aligning the surfaces A and B with the step portions 33, 33 formed by the notches formed in the slice direction collimators 31, 31, by It is possible to accurately align the positions of all blocks. That is, the alignment of the channel direction collimator 32 is performed by the step portion 33 formed by the cutout portions of the slice direction collimators 31, 31.
By using the side surface of 33 as a reference, it is possible to perform accurate alignment between the blocks in the vertical direction and the center direction of the arc.

FIG. 5 shows a state in which a plurality of blocks of the channel-direction collimator 32 are arranged in this way. The slice direction collimators 31, 31 are
Since the structure is integrated over the length of all channels, the arc of the step portion 33 formed by the cutout portion can be processed with high accuracy. Further, since the blocks of the channel-direction collimator 32 having a plurality of configurations are based on the stepped portion 33 formed by the cutout portion of the slice-direction collimator, it is possible to arrange or position with high accuracy. Since the slice direction collimators 31 and 31 are fixed to the detector container 30 and the X-ray detection element is also fixed to the detector container 30, the slice direction collimator 3 is provided.
The relative positions of 1, 31 and the X-ray detection element can also be adjusted with high accuracy.

The pair of holding members 35, 35 forming each block of the channel-direction collimator 32 are arranged in advance.
A plurality of grooves 36, 36 are formed so as to match the curved surface of the step portion 33 formed by the cutout portion of the slice direction collimator 31 and are formed on the inner surfaces facing each other.
... are also formed with an equal angular pitch so as to move toward the focal position of the X-ray tube. According to such a configuration, the blocks of the obtained channel direction collimator 32 become blocks that respectively configure a part of the curved surface, and these blocks are stepped portions 33, 33 due to the cutout portions of the slice direction collimators 31, 31. By being arranged in
Since they are easily arranged at an equal angular pitch so as to move toward the X-ray tube focal position, by adopting such a configuration, the channel direction collimator 32 with high mounting accuracy can be obtained.
It will be clear that it will be possible to obtain

That is, an arc-shaped slice direction collimator centering on the focal point of the X-ray tube is provided so as to be almost in contact with the incident portion of the X-ray detecting element. An arc-shaped step centering around the X-ray tube focal point is also provided inside this slice direction collimator, and the surface on the X-ray incidence side of the channel direction collimator block is abutted against this step position so as to form an adjacent channel direction collimator. If you manage only the interval,
The channel-direction collimator block is automatically arranged at an arc position centered on the X-ray tube focus. In this way, the channel-direction collimator whose alignment has been completed can be incorporated into the slice-direction collimator, and finally the slice-direction collimator incorporating this channel-direction collimator is placed in the correct positional relationship with the X-ray detection element. By adjusting and fixing so that the channel direction collimator and the X-ray detecting cord can be accurately aligned over all channels.

Next, FIG. 6 attached herewith shows the structure of the X-ray detection element arranged in the detector container 30. As is clear from this figure, the printed wiring board 4
3 above the scintillator 4 above the photodiode 42.
A plurality of X-ray detection elements each having a stacked structure of 1 are formed separately. That is, the X-ray detection element in which the scintillator 41 and the photodiode 42 are combined is
On the substrate 43, the adjacent channels are partition plates 46, 46 ...
Are arranged at equal intervals via the, to thereby form a detection element array 47 including a plurality of detection elements.
A connector 44 for connecting a signal cable 45 is attached to the surface of the printed wiring board 43 opposite to the surface on which the detection element is formed.

In the structure of the detection element array 47 in such an X-ray detection element, the partition plates 46, 46 for dividing the plurality of adjacent detection elements are formed by the X-rays incident on the scintillator 41 forming the detection elements. A thin plate made of a material having a high X-ray absorption coefficient, such as tungsten or molybdenum, is used to prevent crosstalk in which light emission or X-ray scattering leaks into adjacent channels. Further, in order to efficiently guide the light emitted from the scintillator 41 to the light receiving portion of the photodiode 42, it is more preferable to use a material whose surface has been subjected to aluminum vapor deposition or the like to have a high light reflectance.

Next, the arrangement structure of the detection element array 47 formed by arranging a plurality of X-ray detection elements in the detector container 30 as described above will be described in detail below. These X-ray detection element arrays 47, 47 ... Are arranged in a polygonal shape in the detector container 30 as shown in FIG. 7 attached or FIG. Note that, also in these drawings, the grid plate forming the above-mentioned channel direction collimator 32 is indicated by a symbol G.

That is, on the X-ray incident surface side of the X-ray detection element array 47, a grid plate G constituting a channel direction collimator 32 for blocking X-rays obliquely incident is arranged. Further, as described above, these grid plates G are arranged at predetermined intervals,
Both end portions thereof are fixed by holding members 35, 35. Specifically, on the side surface of the holding member 35, grooves 36, 3 having an equal angular pitch such that the focal position of the X-ray tube 10 is centered.
6 are formed and the side walls of the grooves 36, 36 ... Are used as guides and the grid plate G is fixed thereto with an adhesive, whereby the mutual positions of the grid plates G are accurately arranged.

In order to maximize the sensitivity of the X-ray detection element to incident X-rays, these grid plates G must be installed so as to match the position of the partition plate 45. By the way, as described above, the plurality of X-ray detection elements forming each X-ray detection element array 47 are arranged at equal intervals on one plane in each detection element array 47. Therefore, assuming that the position of the partition plate 46 in one X-ray detection element array 47 is x, this x is expressed by the following equation. x = n × p where n is the channel number and p is the channel pitch.

Further, a grid plate G constituting a collimator
Are arranged at an equal angle pitch, the position x ′ of the grid plate of this collimator is represented by the following equation. x ′ = r × sin (n × θ) where r is the distance between the X-ray focal point and the grid plate of the collimator, n is the channel number, and θ is the collimator angular pitch.

Here, for example, when the grid plate G of the channel direction collimator 32 and the partition plate 46 are set to coincide with each other at the center of the X-ray detection element array 47, as shown in FIG. In addition, the amount of deviation between the grid plate G forming the collimator and the partition plate 46 of the detection element increases as it goes to the end channel. In FIG. 8B,
The relationship is shown, for example, the distance between the X-ray tube focal point and the detection element is 1000 mm, the channel pitch of the detection element is 1 mm, and one X-ray detection element array 47 is two.
This is an example of calculation in the case of being configured with 4 channels. The maximum shift amount obtained by this calculation is approximately 0.01 mm.

When the thickness of the grid plate G of the collimator and the thickness of the partition plate 46 are the same, the sensitive portion of the channel (X-ray detecting element) when viewed from the direction of the X-ray tube focus. The surface area changes by the above-mentioned amount of deviation. This difference in area appears as a difference in sensitivity and characteristics of the detection element, and in this calculation example, the difference in sensitivity is about 1%, which is a range that does not cause a big problem, but the characteristics As a difference, the difference of 1% is large, which is a size that can cause an artifact on an image.

Therefore, in this embodiment, the thickness (d) of the grid plate G of the collimator is larger than the thickness (d ₀ ) of the partition plate 45 (d> d ₀ ), and specifically, It is set to be equal to or more than the sum of the maximum displacement amounts of the grid plate G and the partition plate 46 (the partition plate thickness d maximum displacement amount). As a result, the area of the sensitive portion surface of the channel when viewed from the direction of the X-ray tube focus becomes the same for all channels on the detection element array 47, and the grid plate G and the partition plate 4 are the same.
Therefore, it is possible to eliminate the influence on the sensitivity and characteristics of the detection element due to the deviation from 6. The thicker the plate thickness of the grid plate G of the collimator, the larger the margin for the channel displacement, but at the same time, the collimator plate thickness also affects the output of the detection element. Therefore, in order to prevent image deterioration due to output reduction, the upper limit of the thickness of the grid plate of this collimator is about 0.2 mm.

In the above-mentioned embodiment, the step portion is provided as the reference line, but any marking may be applied as long as it is provided to properly arrange the collimator and the detector.

As an advantage of the structure of the improved X-ray detector of the X-ray CT apparatus according to the embodiment described above, a highly accurate channel direction collimator can be constructed with a simple structure, and the channel direction collimator It is possible to reduce the number of parts in the part, and it is necessary to align the channel direction collimators with each other, but the number of them is small, so the adjustment time is short, and the pins and holes that are positioned with high precision for alignment. It is possible to combine an accurate channel direction collimator and a solid-state detection element to form an inexpensive detector from the viewpoint of not requiring.

[0043]

As is apparent from the above detailed description, according to the present invention, particularly in an X-ray CT apparatus using a solid-state detector, an X-ray detector that constitutes a solid-state detector together with a channel-direction collimator. These, including the element,
It is possible to arrange and fix the structure with high accuracy and a simple structure, and further suppress the occurrence of artifacts and the like caused by the variation in the characteristics of the X-ray detection element due to such a structure, so that the entire device can be assembled at low cost. Possible,
Moreover, a good tomographic image can be obtained, and the diagnostic ability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing details of a sectional structure of a detector container of an X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an X-ray CT apparatus according to the above embodiment.

FIG. 3 is a perspective view including a partial cross-section showing a structure of a slice direction collimator that constitutes the detector container.

FIG. 4 is a perspective view showing a structure of a block forming a channel direction collimator of the detector container.

FIG. 5 is a front view showing a cross section of the channel direction collimator and a structure in which a plurality of blocks are arranged.

FIG. 6 is a perspective view showing a detection element array formed on a printed wiring board of the detector container.

FIG. 7 is a partially enlarged cross-sectional view showing an arrangement relationship between a grid of the channel direction collimator and a detection element array.

FIG. 8 is a diagram for explaining a positional shift in the arrangement relationship between the grid of the channel direction collimator and the detection element array.

FIG. 9 is a diagram illustrating the relationship between the structure of a conventional ionization chamber detection element and scattered X-rays.

FIG. 10 is a diagram illustrating the relationship between the structure of a conventional solid-state detection element and scattered X-rays.

[Explanation of symbols]

 10 X-ray generation source (X-ray tube) 20 Subject 30 Detector container 31 Slice direction collimator 32 Channel direction collimator 33 Stepped portion 34 Screw 35 Holding material 36 Groove 41 Scintillator 42 Photodiode 43 Printed wiring board (board) 44 Connector 45 Signal cable 46 Partition plate 47 Detection element array E Detector incident part G Grid plate (collimator plate)

Claims (3)

[Claims] 1. An X-ray generation source that emits X-rays, and X inside.
An arc-shaped detector container in which an X-ray detection means is arranged in an arc shape with the X-ray generation source as a center, and X-rays emitted from the X-ray generation source are directed to the incident surface side of the arc-shaped detector container. An X-ray CT apparatus which obtains a tomographic image of an object by limiting the width of the X-ray CT through an arc-shaped collimator in a slice direction and thereby obtaining the tomographic image of the subject, wherein Between the arc-shaped slice direction collimator and the X-ray detecting means arranged in the arc shape, a plurality of grid plates are arranged at equal angles with respect to the X-ray generation source, and a channel-direction collimator is arranged. The channel direction collimator is divided into a plurality of blocks in the channel direction to form blocks, and the blocks of the plurality of channel direction collimators are divided into the X-rays of the arc-shaped slice direction collimator. X-ray CT apparatus characterized by incorporating reference to a predetermined reference line of the end portion of the detecting means side. 2. The X-ray CT apparatus according to claim 1, wherein the X-ray detection means separates the X-ray detection element formed by stacking a light conversion element and a scintillator at equal intervals by a partition plate. Then, a plurality of X-ray detection element arrays, which are configured by arranging a plurality of these detection elements on a substrate at equal intervals, are provided inside the detector container as a polygon along a circular arc centered on the X-ray generation source. An X-ray CT apparatus characterized in that the X-ray CT apparatus is arranged in a shape of a circle. 3. The X-ray CT apparatus according to claim 2, wherein the grid plate constituting the channel direction collimator has a thickness of at least X formed on the substrate.
An X-ray CT apparatus characterized in that it is made thicker than the thickness of the partition plate arranged between the respective detection elements of the line detection element array.