JPH11285489A - Radiation exposure position adjusting method, radiation exposure and detection device and tomograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent photographic radiation from being exposed to an extra part having nothing to do with photographing and reduce an exposure dose by calibrating so that the range of photographing may be shielded from radiation with a shutter, when the exposure position in the thickness direction of a radiation beam is to be adjusted on a radiation detector. SOLUTION: A tomograph is equipped with an operating gantry, a photographic table, and an operating console, and the operating gantry is provided with an X-ray tube 20 as a source of radiation. X-rays irradiated from the X-ray tube 20 are turned into a fan-shaped X-ray beam with a collimator 22 and irradiated to a detector array 24. In this case, to protect the subject against exposure at a time when the X-ray exposure position is to be adjusted with a subject placed on the photographic table, the collimator 22 is provided with a shutter 224 that closes partially the aperture. The shutter 224 is made from an X-ray shielding material such as a lead plate, and the range 82 of photographing is set so that X-rays may be exposed only to parts near both ends of the detector array 24 by shielding it from the X-rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a radiation irradiation position, a radiation irradiation / detection apparatus, and a radiation tomography apparatus, and more particularly to irradiating a radiation beam having a width and a thickness, and applying the radiation beam to a radiation detecting element array. Radiation irradiation / detection device and such radiation irradiation /
The present invention relates to a radiation irradiation position adjusting method for a detection device, and a radiation tomography apparatus including such a radiation irradiation / detection device.

[0002]

2. Description of the Related Art As an example of a radiation tomography apparatus, there is, for example, an X-ray computed tomography (CT) apparatus. In an X-ray CT apparatus, X-rays are used as radiation. An X-ray tube is used for X-ray generation. Then, the radiation irradiation / detection system, that is, the X-ray irradiation / detection system is rotated (scanned) around the subject, and the subject is exposed to X-rays in a plurality of views around the subject. Is measured, and a tomographic image is generated (reconstructed) based on the projection data.

An X-ray irradiator has an X-ray beam (b) having a width encompassing an imaging range and having a predetermined thickness in a direction perpendicular thereto.
eam). The thickness of the X-ray beam is determined by the collimator (colli
It is set by the degree of opening of the X-ray aperture (aperture) of the meter).

The X-ray detecting apparatus detects X-rays by a multi-channel X-ray detector in which a large number of X-ray detecting elements are arranged in an array in the direction of the width of the X-ray beam. The multi-channel X-ray detector has a length (width) corresponding to the width of the X-ray beam in the direction of the width of the X-ray beam.
In addition, it has a length (thickness) greater than the thickness of the X-ray beam in the direction of the thickness of the X-ray beam.

[0005] Some X-ray detectors have an array of X-ray detecting elements in two rows so that projection data for two slices can be obtained at once. There, two rows of arrays are arranged adjacent to and parallel to each other, and the X-ray beam is uniformly distributed in the thickness direction and irradiated. The thickness of the X-ray beam applied to each of the two arrays at the isocenter of the subject determines the slice thickness of the tomographic image.

In the X-ray tube, the focal point of the X-ray moves due to thermal expansion or the like due to a rise in temperature during use, and this shift appears as a displacement in the thickness direction of the X-ray beam through the aperture of the collimator. When the X-ray beam is displaced in the thickness direction, 2
The distribution ratio of the thickness of the X-ray beam in the row array changes, and the slice thickness of the subject projected on the two arrays is not uniform.

Therefore, the X-ray count (coupe) in the reference channel of the two-row array is considered.
(nt) is monitored, and since the ratio is no longer 1, the deviation of the X-ray irradiation position is recognized, and the irradiation position is corrected. Such correction of the irradiation position is performed with the subject mounted on the imaging table before the start of the scan, and between scans, as appropriate, with the subject mounted on the imaging table.

[0008]

When the irradiation position is corrected as described above, the subject is exposed to extra X-rays unrelated to imaging in addition to X-rays for imaging, so that the amount of exposure increases. There's a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for adjusting a radiation irradiation position in which a subject is not exposed to radiation, and a method of adjusting a radiation irradiation position in which the subject is not exposed to radiation when adjusting the irradiation position. A detection device and a radiation tomography device including such a radiation irradiation / detection device are to be realized.

[0010]

Means for Solving the Problems (1) According to a first aspect of the present invention, one of two directions perpendicular to an irradiation direction and perpendicular to each other has a relatively large width in one of the two directions. Radiation irradiating means for irradiating a radiation beam having a relatively small thickness, and a plurality of radiation detecting elements having a length larger than the thickness of the radiation beam in the direction of the thickness of the radiation beam, A radiation irradiation position adjusting method for a radiation irradiation / detection device, comprising: a radiation detection element array arranged in the direction of (a), excluding a space where a subject exists between the radiation irradiation means and the radiation detection element array. Irradiating the radiation beam to the radiation detecting element array, and irradiating the radiation on the radiation detecting element array based on a radiation detection signal of the radiation detecting element array. Adjusting the irradiation position of the thickness direction of the beam, an irradiation position adjustment method of radiation-detecting device, characterized in that.

(2) A second aspect of the present invention for solving the above-mentioned problem is that one of two directions perpendicular to the irradiation direction and perpendicular to each other has a relatively large width and the other has a relatively small width. Radiation irradiating means for irradiating a radiation beam having a thickness, and a plurality of radiation detection elements having a length greater than the thickness of the radiation beam in the direction of the thickness of the radiation beam are arranged in the direction of the width of the radiation beam. A radiation detecting element array, comprising: a radiation irradiating / detecting device having a radiation detecting element array, wherein the radiation irradiating element array irradiates the radiation detecting element array with the radiation beam except for a space between the radiation irradiating means and the radiation detecting element array where a subject exists. Irradiation range adjusting means, and a radiation detection signal of the radiation detecting element array relating to the radiation beam adjusted by the irradiation range adjusting means. Radiation · characterized by comprising an irradiation position adjusting means for adjusting an irradiation position of the thickness direction of the radiation beam on the serial radiation detector array
It is a detection device.

(3) A third aspect of the present invention for solving the above-mentioned problems is that one of two directions perpendicular to the irradiation direction and perpendicular to each other has a relatively large width and the other has a relatively small width. Radiation irradiating means for irradiating a radiation beam having a thickness, and a plurality of radiation detection elements having a length greater than the thickness of the radiation beam in the direction of the thickness of the radiation beam are arranged in the direction of the width of the radiation beam. A radiation tomography apparatus, comprising: a radiation detection element array; and a tomographic image generation unit configured to generate a tomographic image of a passage area of the radiation beam based on radiation detection signals of a plurality of views by the radiation detection element array, Except for the space where the subject exists between the radiation irradiating means and the radiation detecting element array, the radiation beam is applied to the radiation detecting element array. Irradiation range adjusting means for irradiating, and adjusting the irradiation position in the thickness direction of the radiation beam on the radiation detection element array based on the radiation detection signal of the radiation detection element array regarding the radiation beam adjusted by the irradiation range adjustment means. And a radiation position adjusting means.

In the second invention or the third invention, the irradiation range adjusting means includes a shielding member for shielding a space between the radiation irradiating means and the radiation detecting element array where the subject exists from the radiation. Is preferable in that the irradiation range is effectively adjusted.

[0014] In the second or third invention, the irradiation range adjusting means may irradiate radiation except for a space where the subject exists between the radiation irradiating means and the radiation detecting element array. To have a passing window,
This is preferable in that the irradiation range can be effectively adjusted.

In this case, it is preferable that the radiation passage window is provided in the collimator in order to simplify the configuration. (Function) In the present invention, the radiation detecting element array is irradiated with a radiation beam except for the space where the subject exists between the radiation irradiating means and the radiation detecting element array, and the radiation detecting element array is generated based on the radiation detection signal. The irradiation position of the above radiation beam in the thickness direction is adjusted.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

FIG. 1 shows a block diagram of the X-ray CT apparatus. This device is an example of an embodiment of the present invention. The configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention. An example of an embodiment of the method of the present invention is shown by the operation of the present apparatus.

As shown in FIG. 1, this apparatus comprises a scanning gantry 2, a photographing table 4, and an operation console (c).
onsole) 6. The scanning gantry 2 has an X-ray tube 20 as a radiation source. An X-ray (not shown) emitted from the X-ray tube 20 is converted into, for example, a fan-shaped X-ray beam by the collimator 22 and is applied to the detector array 24. The X-ray tube 20 and the collimator 22 are an example of an embodiment of a radiation irradiation unit in the present invention.
The collimator 22 is an example of an embodiment of the irradiation range adjusting means in the present invention.

The detector array 24 is an example of an embodiment of the radiation detecting element array according to the present invention. The detector array 24 has a plurality of X-ray detection elements arranged in an array in the direction of the width of the fan-shaped X-ray beam. The configuration of the detector array 24 will be described later.

The X-ray tube 20, collimator 22 and detector array 24 constitute an X-ray irradiation / detection system. The configuration of the X-ray irradiation / detection system will be described later. A data collection unit 26 is connected to the detector array 24. The data collection unit 26 collects detection data of individual X-ray detection elements of the detector array 24.

The irradiation of X-rays from the X-ray tube 20 is controlled by an X-ray controller (controller) 28. The illustration of the connection relationship between the X-ray tube 20 and the X-ray controller 28 is omitted. Collimator 22
Are controlled by the collimator controller 30. The illustration of the connection relationship between the collimator 22 and the collimator controller 30 is omitted.

The above-mentioned X-ray tube 20 to collimator controller 30 are mounted on the rotating unit 32 of the scanning gantry 2. The rotation of the rotation unit 32 is controlled by a rotation controller 34. The illustration of the connection relationship between the rotation unit 32 and the rotation controller 34 is omitted.

The imaging table 4 carries a subject (not shown) into and out of the X-ray irradiation space of the scanning gantry 2. The relationship between the subject and the X-ray irradiation space will be described later.

The operation console 6 has a central processing unit 60. The central processing unit 60 is an example of an embodiment of a tomographic image generation unit according to the present invention. Central processing unit 6
0 is composed of, for example, a computer. The central processing unit 60 has a control interface (int
erface) 62 is connected. Control interface 6
2, a scanning gantry 2 and an imaging table 4 are connected.

The central processing unit 60 has a control interface 6
2, the scanning gantry 2 and the imaging table 4 are controlled. The data acquisition unit 26, X-ray controller 28, collimator controller 30, and rotation controller 34 in the scanning gantry 2 are controlled through a control interface 62. In addition, illustration of individual connections between each unit and the control interface 62 is omitted.

Central processing unit 60, control interface 6
2. Collimator controller 30 and collimator 22
The portion consisting of is an example of an embodiment of the irradiation position adjusting means in the present invention.

A data acquisition buffer 64 is also connected to the central processing unit 60. Data collection buffer 6
4 is connected to the data collection unit 26 of the scanning gantry 2. The data collected by the data collection unit 26 is input to the data collection buffer 64. Data collection buffer 6
Reference numeral 4 temporarily stores input data.

The X-ray tube 20, the collimator 22, the detector array 24, the data acquisition unit 26, the data acquisition buffer 64,
The part including the central processing unit 60, the control interface 62, and the collimator controller 30 is an example of an embodiment of the radiation irradiation / detection device of the present invention.

The central processing unit 60 also has a storage device 6
6 are connected. The storage device 66 stores various data, reconstructed images, programs, and the like.
The display device 68 and the operation device 70 are also connected to the central processing unit 60. The display device 68 displays a reconstructed image and other information output from the central processing unit 60. The operation device 70 is operated by an operator, and inputs various instructions and information to the central processing unit 60.

FIG. 2 shows a schematic configuration of the detector array 24. The detector array 24 has a large number (for example, 1000)
X-ray detectors 242 and 244 of two rows in which the X-ray detection elements 24 (i) are arranged in an arc shape. i is a channel number, for example, i = 1 to 1000
It is. The X-ray detectors 242 and 244 are adjacent to each other in parallel.

FIG. 3 shows the relationship among the X-ray tube 20, the collimator 22, and the detector array 24 in the X-ray irradiation / detection system. 3A is a front view, and FIG. 3B is a side view. As shown in FIG.
The rays are converted into a fan-shaped X-ray beam 40 by the collimator 22 and irradiated to the detector array 24.
FIG. 3A shows the spread of the fan-shaped X-ray beam 40, that is, the width of the X-ray beam 40. FIG. 3B shows the thickness of the X-ray beam 40. The X-ray beam 40 is applied to two rows of X-ray detectors 242 and 244 with uniform thickness distribution.

With the body axis crossing the fan-shaped surface of the X-ray beam 40, the subject 8 placed on the imaging table 4 is carried into the X-ray irradiation space, for example, as shown in FIG. . A projection image of the subject 8 sliced by the X-ray beam 40 is projected on the detector array 24. Each half of the thickness of the X-ray beam 40 at the isocenter of the subject 8 gives two slice thicknesses th of the subject 8. The slice thickness th is determined by the X-ray passing aperture (aperture) of the collimator 22.

X-ray beam 40 for detector array 24
FIG. 5 shows a more detailed schematic diagram of the irradiation state of FIG. As shown in FIG.
By displacing 0, 222 in the direction to narrow the aperture, the slice thickness th of the projected image in the X-ray detectors 242, 244 can be reduced. Further, by moving the collimator pieces 220 and 222 in the direction in which the aperture is widened, the slice thickness th of the projected image can be increased.

Further, by simultaneously moving the collimator pieces 220 and 222 with the slice thickness th set, while keeping the relative positional relationship fixed, the X-rays on the detector array 24 are obtained.
The irradiation position of the line beam 40 in the thickness direction is changed. Note that the irradiation position in the thickness direction is changed by displacing the detector array 24 relative to the collimator 22 in the thickness direction of the X-ray beam 40, as shown by a dashed arrow, instead of moving the collimator pieces 220 and 222. May be performed. With this configuration, two systems can be separately provided for the slice thickness adjustment mechanism and the irradiation position control mechanism in the thickness direction, and multilateral control is possible. On the other hand, if all the operations are performed by the collimator 22 as described above, the control system can be unified into one system, and the demand for simplification can be met.

The X-ray irradiation / detection system including the X-ray tube 20, the collimator 22, and the detector array 24 rotates (scans) around the body axis of the subject 8 while maintaining their mutual relationship. A plurality (for example, 100
Projection data of the subject is collected at the view angle of 0).
The collection of projection data is performed by a system including the detector array 24, the data collection unit 26, and the data collection buffer 62.

Based on the projection data of two slices collected in the data collection buffer 62, the central processing unit 60 generates tomographic images of two slices, that is, performs image reconstruction. Image reconstruction is performed, for example, by using projection back data of, for example, 1000 views obtained by one rotation scan, for example, using filtered back-projection.
(ion) method.

FIG. 6 shows an example of the configuration of the X-ray incidence surface of the detector array 24. As shown in the figure, at the end of the detector array 24, for example, ten X-ray detection elements 250 to 258, 270 to 278 for detecting the irradiation position are provided.
The X-ray detection elements 250 to 258 are a part of the X-ray detector 242. The X-ray detection elements 270 to 278 are part of the X-ray detector 244. These X-ray detecting elements are 250 and 270, 252 and 272,.
78 form a pair.

These X-ray detecting elements 250 to 258, 27
The vicinity of the end of the detector array 24 provided with 0 to 278 is outside the range where the transmission image of the subject 8 is projected, and the X-rays from the X-ray tube 20 pass through the subject 8. Irradiated directly without.

X-ray detecting elements 250 to 258, 270 to 2
Reference numeral 78 indicates that the X-ray receiving surface is partially shielded by an X-ray shielding plate 290 made of, for example, a lead plate, and the other portion is a light receiving surface. The X-ray shielding plate 290
For the line detecting elements 250 and 270, for example, the X-ray beam 401 having a slice thickness of 1 mm at the isocenter is used.
Are uniformly distributed to the X-ray detectors 242 and 244, and are irradiated with X-rays.

Similarly, for the X-ray detection elements 252 and 272, for example, the area where the X-ray beam 403 having a slice thickness of 3 mm is irradiated is blocked, and the X-ray detection elements 254 and 272 are blocked.
74, for example, X with a slice thickness of 5 mm
X-ray detection element 2
For 56 and 276, for example, the slice thickness is 7 mm
X-ray beam 407 is shielded, and X-ray detection elements 258 and 278 are shaped so as to block the area where X-ray beam 410 having a slice thickness of 10 mm is applied.

Such X-ray detecting elements 250 to 258,
When the X-ray beams are uniformly distributed and irradiated to the X-ray detectors 242 and 244 instead of covering the light receiving surface with the X-ray shielding plate 290, the X-ray beams
Needless to say, the light receiving surface may be configured to have a light receiving surface in a region other than the region corresponding to the reference numerals 1 to 410.

Such X-ray detecting elements 250 to 258,
The X-ray detection signals from 270 to 278
Through the data collection buffer 64. The central processing unit 60 detects an X-ray irradiation position in the detector array 24 based on the X-ray detection signals, and adjusts the X-ray irradiation position.

Detection and adjustment of the irradiation position of the X-ray beam having a slice thickness of 1 mm are performed using detection signals of the X-ray detection elements 250 and 270. Similarly, slice thicknesses 3, 5, 7, 1
The detection and adjustment of the irradiation position of the 0-mm X-ray beam are performed by the X-ray detection elements 252, 272, 254, 274, and 2 respectively.
The detection is performed using the detection signals 56, 276, 258, and 278. It is preferable to provide an X-ray detecting element having the same configuration at the other end of the detector array 24 in order to more accurately detect and adjust the X-ray irradiation position.

In order to prevent the subject 8 from being exposed when the X-ray irradiation position is adjusted while the subject 8 is placed on the imaging table 4, the collimator 22 has a structure shown in FIG. A shutter that partially closes the aperture 2
24 are provided. Shutter 224 Shutter 224
Is an example of an embodiment of a shielding member in the present invention. Imaging range of this device, that is, FOV (field of view)
82 is shielded from X-rays,
The X-rays are applied only to the vicinity of both ends of the detector array 24 provided with 258, 270 to 278.

The shutter 224 is made of, for example, an X-ray shielding material such as a lead plate. The shutter 224 is controlled by the collimator controller 30, and as shown in FIG.
In the state of shielding X-rays from the X-ray, or canceling the shielding and FO
One of the states enabling the passage of X-rays in V82 is taken.

The operation of the present apparatus will be described. Prior to imaging,
The X-ray irradiation position on the detector array 24 is adjusted as described below so that the thickness of the X-ray beam 40 is evenly distributed to the X-ray detectors 242 and 244 in two rows. F
When adjusting the X-ray irradiation position in a state where the subject 8 is present in the OV 82, the shutter 224 is used to adjust the X-ray irradiation position as shown in FIG.
This is performed while the OV 82 is shielded from X-rays.

Hereinafter, the slice thickness at the isocenter is set to 10
The adjustment of the X-ray irradiation position will be described using an example in which the X-ray beam 410 having a thickness of mm is used. Now, as shown in FIG. 8, if the X-ray beam 410 is irradiated to the X-ray detectors 242 and 244 with uneven distribution, the X-ray detection element 258 has a light receiving surface that is not shielded by the X-ray shielding plate 290. X-rays strike the X-ray detecting element 278 at the portion shielded by the X-ray shielding plate 290. Therefore, the X-ray detection element 25
8 generates an X-ray detection signal, and the X-ray detection element 278 does not generate an X-ray detection signal.

The central processing unit 60 includes the X-ray detecting element 25
8, 278 based on the combination of such X-ray detection signals, the irradiation position of the X-ray beam 410 is determined by the X-ray detector 2.
It recognizes that it is shifted to the 42 side. Then, by controlling the collimator 22, the irradiation position deviation is corrected. Alternatively, when a position adjusting mechanism for the detector array 24 is provided, the irradiation position shift is corrected by changing the position of the detector array 24.

As the correction proceeds, the X-ray receiving area of the X-ray detecting element 258 decreases, and the X-ray detection signal decreases accordingly. Then, when the distribution of the X-ray beams 410 becomes uniform, as shown in FIG. 9, the X-ray beams 410 come to hit only the area shielded by the X-ray shield plate 290, so that the X-ray detection elements 258 and 278 Both X-ray detection signals become 0. The central processing unit 60 recognizes that the irradiation position of the X-ray beam 410 has been optimized based on such a signal state, and ends the adjustment.

When the slice thickness is 1, 3, 5, 7 mm, the X-ray detection elements 250, 270, 252,
The same irradiation position adjustment is performed using the X-ray detection signals of 272, 254, 274, 256, and 276. In either case, since the X-ray detection signals of the pair of X-ray detection elements both become 0, it is recognized that the irradiation position is appropriate. Therefore, the sensitivity difference between the X-ray detection elements or the amplification of those signals is performed. , Etc., is not affected by differences in the gains of the amplifiers.

During such X-ray irradiation position adjustment, FOV
The subject 8 is not exposed to X-rays because the shutter 82 is shielded from X-rays. Therefore,
The subject 8 is not exposed to unnecessary exposure. After the adjustment of the X-ray irradiation position as described above, the F
The shielding of the OV 82 is released, the subject 8 is scanned by the X-ray irradiation / detection system, and projection data of, for example, 1000 views is collected in the data collection buffer 62. Based on the projection data, the central processing unit 60 performs image reconstruction using, for example, a filtered back projection method.

Since the detector array 24 has two rows of X-ray detectors in parallel, it is possible to obtain tomographic images of two adjacent slices at once by one scan. As a result, the efficiency in performing a multi-slice scan or a helical scan is improved, and two slices have the same slice thickness. The reconstructed image is displayed on the display device 68 and stored in the storage device 66.

When the irradiation position of the X-ray beam 40 shifts between scans due to a change in the temperature of the X-ray tube 20 or the like, the FOV 82 is blocked by the shutter 224 and the irradiation position is corrected in the same manner as described above. The scanning is always performed with an even slice thickness.

FIG. 10 shows an example of a collimator having a shutter function. As shown in FIG. 9A, a pair of collimator pieces 22 facing each other by forming an aperture 226 are formed.
0 ′ and 222 ′ have notches 228 at both ends.
The notch 228 is an example of an embodiment of the radiation passage window in the present invention. The notch 228 indicates that the X-rays passing therethrough have the X-ray detecting elements 250 to 25 of the detector array 24.
8, 270 to 278 are formed so as to be incident.

These notches 228 are shown in FIG.
As shown in FIG. 7, since the aperture 226 is not closed even when it is closed, the FOV 82 is shielded from X-rays while
X-rays can be applied to the line detection elements 250 to 258, 270 to 278. Such a collimator 22 ′
It is preferable that the collimator pieces 220 'and 222' also function as shutters and the configuration is simplified.

FIG. 11 shows an example in which a shutter is combined with a cylindrical collimator. As shown in the figure, the collimator 22 ″ is formed in a cylindrical shape, and has a plurality of slits 232 parallel to the axis on a cylindrical surface. Multiple slits 23
2 are formed so as to have a predetermined width, respectively, and similar slits are formed in pairs on the other surface of the cylinder opposed thereto, thereby forming an aperture for X-ray passage. The switching of the aperture is performed by rotating the collimator 22 ″ in the circumferential direction.

For such a collimator 22 ″, a shutter 224 is provided so as to be able to advance and retreat to block the X-rays passing through the aperture for the FOV 82.
Thus, when the shutter 224 is operated, the FOV
X-ray detecting elements 250 to 25 while shielding 82 from X-rays
X-rays can be irradiated to 8,270 to 278.

A predetermined slit in the cylindrical collimator is, for example, as shown in FIG.
Slit 2 for applying X-rays only to 258,270-278
34, the X-ray detection element 2
50 to 258, 270 to 278 can be irradiated with X-rays. This is also preferable in that the shutter plate is not required and the configuration is simplified. The slit 234 is an example of an embodiment of the radiation passage window in the present invention.

The adjustment of the X-ray irradiation position with respect to the detector array is not limited to the detector array using the two-row array, but may also be required in the detector array using the single-row array. That is, when the sensitivity of the X-ray detection element 24 (i) changes in the direction of the thickness of the X-ray beam,
When the X-ray irradiation position on the detector array changes due to the movement of the X-ray focal point or the like, the detection signal of the X-ray detection element 24 (i) changes, causing a false image such as a ring artifact. Therefore, it is necessary to control the X-ray irradiation position to be always constant.

FIG. 13 shows an example of the configuration of the X-ray incident surface of the detector array 24 for performing such X-ray irradiation position adjustment. As shown in the figure, an X-ray detecting element 250 for detecting an irradiation position is provided at an end of the detector array 24. The vicinity of the end of the detector array 24 provided with the X-ray detection element 250 is out of the range where the transmission image of the subject is projected, whereby X-rays from the X-ray tube 20 are 8
Irradiated directly without transmitting through.

The X-ray detecting element 250 has its X-ray incident surface 2
The width of 60 is gradually changed according to the thickness direction of the X-ray beam 40, that is, the distance in the z direction. Such an X-ray detecting element 250 is provided in the detector array 2
The front surface of the X-ray detecting element at the end of No. 4 is half covered diagonally with an X-ray shielding plate 290.

Since the X-ray detecting element 250 has such an X-ray incident surface 260, when the X-ray beam 40 is displaced in the z direction, the X-ray detection signal of the X-ray detecting element 250 changes accordingly. Therefore, the X-ray detection element 250
Can indicate the irradiation position of the X-ray beam 40 on the detector array 24 in the thickness direction.
The central processing unit 60 recognizes the irradiation position of the X-ray beam based on such an X-ray detection signal and corrects the position shift.

During the adjustment of the irradiation position of the X-ray beam, the shutter 224 or the collimators 22 ', 2
By shielding the FOV 82 from X-rays by 2 '',
Unnecessary exposure of the subject 8 can be avoided.

Although the example using X-rays as radiation has been described above, the radiation is not limited to X-rays, but may be other types of radiation such as γ-rays. However,
At present, X-rays are preferred because practical means for generating, detecting, controlling, and the like are the most substantial.

[0065]

As described above in detail, according to the present invention, a radiation irradiation position adjusting method in which a subject is not exposed to radiation, and a radiation irradiation / detection apparatus in which the subject is not exposed to radiation when adjusting the irradiation position. , And a radiation tomography apparatus including such a radiation irradiation / detection apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to an example of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a detector array in an apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an X-ray irradiation / detection system in an apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an X-ray irradiation / detection system in an apparatus according to an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an X-ray irradiation / detection system in an apparatus according to an embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a detector array in the device according to an example of the embodiment of the present invention.

FIG. 7 is a schematic view showing a state of irradiating a detector array with X-rays in an apparatus according to an embodiment of the present invention.

FIG. 8 is a schematic diagram showing a state of irradiating a detector array with X-rays in an apparatus according to an embodiment of the present invention.

FIG. 9 is a schematic diagram showing a state of X-ray irradiation on a detector array in the apparatus according to an example of the embodiment of the present invention.

FIG. 10 is a schematic diagram illustrating a configuration of a collimator in an apparatus according to an embodiment of the present invention.

FIG. 11 is a schematic diagram showing a configuration of a collimator in an apparatus according to an embodiment of the present invention.

FIG. 12 is a schematic diagram illustrating a configuration of a collimator in an apparatus according to an example of an embodiment of the present invention.

FIG. 13 is a graph showing an X-ray irradiation state detection signal to a detector array in the apparatus according to an embodiment of the present invention.

[Explanation of symbols]

2 Scanning Gantry 20 X-ray Tube 22, 22 ', 22''Collimator 24 Detector Array 26 Data Collection Unit 28 X-ray Controller 30 Collimator Controller 32 Rotating Unit 34 Rotation Controller 4 Imaging Table 6 Operation Console 60 Central Processing Unit 62 Control Interface 64 Data acquisition buffer 242,244 X-ray detector 40,401,403,405,407,410 X-ray beam 8 Subject 220,222 Collimator piece 224 Shutter 24 (i), 250-258,270-278 X-ray detection Element 290 X-ray shielding plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Gono 127 GYokogawa Medical System Co., Ltd., 4-7 Asahigaoka, Hino-shi, Tokyo

Claims (3)

[Claims] 1. A radiation irradiating means for irradiating a radiation beam having a relatively large dimension width in one of two directions perpendicular to the irradiation direction and perpendicular to each other, and a relatively small dimension thickness in the other direction. A radiation detection element array in which a plurality of radiation detection elements having a length greater than the thickness of the radiation beam in the direction of the thickness of the radiation beam are arranged in the direction of the width of the radiation beam; A radiation irradiation position adjusting method, comprising irradiating the radiation detection element array with the radiation beam except for a space where a subject exists between the radiation irradiation means and the radiation detection element array, Adjusting the irradiation position in the thickness direction of the radiation beam on the radiation detection element array based on the radiation detection signal of, Irradiation position adjustment method that radiation-detecting device. 2. A radiation irradiating means for irradiating a radiation beam having a relatively large dimension width in one of two directions perpendicular to the irradiation direction and perpendicular to each other, and a relatively small dimension thickness in the other direction. A radiation detection element array in which a plurality of radiation detection elements having a length greater than the thickness of the radiation beam in the direction of the thickness of the radiation beam are arranged in the direction of the width of the radiation beam; An irradiation range adjustment unit that irradiates the radiation beam to the radiation detection element array except for a space where a subject exists between the radiation irradiation unit and the radiation detection element array, and the irradiation range adjustment unit. The radiation on the radiation detection element array based on the radiation detection signal of the radiation detection element array regarding the adjusted radiation beam; Beam radiation and detection device characterized by comprising a an irradiation position adjusting means for adjusting the irradiation position in the thickness direction of the. 3. A radiation irradiating means for irradiating a radiation beam having a relatively large dimension width in one of two directions perpendicular to each other and perpendicular to the irradiation direction, and a relatively small dimension thickness in the other direction. A radiation detection element array in which a plurality of radiation detection elements having a length greater than the thickness of the radiation beam in the direction of the thickness of the radiation beam are arranged in the direction of the width of the radiation beam; A tomographic image generating means for generating a tomographic image for the passage area of the radiation beam based on the radiation detection signal of the view, wherein the radiation tomography apparatus comprises: Irradiating range adjusting means for irradiating the radiation beam to the radiation detecting element array excluding a space where a subject exists; Irradiation position adjustment means for adjusting the irradiation position of the radiation beam in the thickness direction on the radiation detection element array based on the radiation detection signal of the radiation detection element array regarding the radiation beam adjusted by the range adjustment means. A radiation tomography apparatus characterized by the above-mentioned.