JPH1189825A - Radiation irradiating and detecting device and radiation tomographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radiation irradiating and detecting device capable of unnecessitating preliminary measurement for detecting an irradiating position by using even number of radiation detecting elements each half of which is provided with a radiation receiving surface on a side opposite to each other concerning the center of the thickness of a radiation detecting element array for detecting the irradiating position of radiation beams. SOLUTION: A scanning gantry 2 is obtained by forming X-rays radiated from an X-ray tube 20 as a radiation source to make fan-shaped X-ray beams by a collimator 22 and then irradiating it to a detector array 24, and the X-ray tube 20 and a collimator controller 30 of these are mounted to the rotation part 32 of the gantry 2. The array 24 is provided by constitution even number of X-ray detecting elements each half of which is provided with a radiation receiving surface on a side opposite to each other concerning the center of the array 24 in the thickness direction of the X-ray beams at least at one tip part. Then, a central processor 60 detects the irradiating position of the X-ray beams at the array 24 by the processor 60 based on the output signal of the even number of X-ray detecting elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation irradiating / detecting apparatus and a radiation tomography apparatus, and more particularly to irradiating and detecting a radiation beam having a width and a thickness and receiving the radiation beam by a radiation detecting element array. The present invention relates to an apparatus and a radiation tomography apparatus including such a radiation irradiation / detection apparatus.

[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. And the radiation irradiation / detection system, that is, X-ray irradiation /
The detection system is rotated (scanned) around the object, and the projection data (data) of the object is measured by X-rays in a plurality of view directions around the object, and the projection data is measured. A tomographic image is generated (reconstructed) based on.

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 X-ray detection device detects X-rays by a multi-channel X-ray detector in which a large number of X-ray detection elements are arranged in an array in the direction of the width of the X-ray beam.

[0004] The X-ray detector is arranged in the direction of the width of the X-ray beam.
It has a dimension (width) corresponding to the width of the X-ray beam. Also,
It has a larger dimension (thickness) in the direction of the thickness of the X-ray beam than the thickness of the X-ray beam.

[0005] The thickness of the X-ray beam is determined by the slice of tomography.
(slice) Determine the thickness. The slice thickness is adjusted to an appropriate value according to the purpose of photographing. To adjust the slice thickness,
A collimator for adjusting the thickness of the X-ray beam is used. The collimator also controls the irradiation position in the thickness direction of the X-ray beam on the X-ray detector.
Thus, for example, the X-ray beam is controlled so as to always enter the center in the thickness direction of the X-ray detector, and X-ray detection can be performed with a known sensitivity that is calibrated in advance for each X-ray detection element. ing.

In order to control the irradiation position of the X-ray beam on the X-ray detector, the X-ray in the thickness direction of the X-ray detector is controlled.
It is necessary to detect the irradiation position of the line beam. For this purpose, as shown in FIG. 11, X-ray detection elements 92 to 96 for detecting the irradiation position are provided at the end of the X-ray detector 90.

The X-ray detecting elements 92 to 96 are arranged such that the width of the X-ray incident surface given as a composite of the X-ray incident surfaces 920 to 960 is a distance in the direction of arrow 98, that is, the direction of the thickness of the X-ray beam 100. It changes gradually according to.

Such X-ray detecting elements 92 to 96
At the end of the X-ray detector 90, the X-ray detection elements 92 to 9
6, the X-ray incidence surface is half covered diagonally with an X-ray shielding plate 970.

Since the X-ray detecting elements 92 to 96 have such X-ray incident surfaces 920 to 960, when the X-ray beam 100 is displaced in the direction of its thickness, the X-rays are correspondingly displaced.
The sum of the X-ray detection signals of the line detection elements 92 to 96 changes.
Accordingly, the irradiation position of the X-ray beam 100 in the thickness direction of the X-ray detector 90 can be known based on the sum of the X-ray detection signals of the X-ray detection elements 92 to 96.

[0010]

SUMMARY OF THE INVENTION
In order to detect the X-ray irradiation position in the thickness direction of the X-ray detector, the relationship between the X-ray irradiation position in the X-ray detector in the thickness direction and the X-ray detection signal must be obtained in advance. That is, the X-ray beam 1 in the X-ray detector 90
It is necessary to measure the irradiation position in the thickness direction of 00 by some method, measure the sum of the X-ray detection signals of the X-ray detection elements 92 to 96 at each irradiation position, and obtain the relationship between the two measured values.

In particular, in order to control the irradiation position of the X-ray beam 100 at the center of the X-ray detector 90 in the thickness direction based on the irradiation position detection signal, the X-ray beam 100 must be controlled in advance. It is necessary to correctly determine the value of the X-ray detection signal when irradiating the center of the detector 90 in the thickness direction.

In this case, even if the irradiation position is the same, the value of the X-ray detection signal differs depending on the thickness of the X-ray beam 100.
In an X-ray CT apparatus in which the thickness of the X-ray beam 100 is variable, X
It is necessary to change the thickness of the line beam 100 to obtain an X-ray detection signal.

The irradiation position of the X-ray beam is determined by the X-ray detection element 9.
A photosensitive film is attached in the vicinity of 2 to 96, and it is determined from the position of the X-ray beam image exposed to it.
Since this method requires the development of the film and the like, the workability is poor. In particular, when the relationship between the irradiation position and the X-ray detection signal is obtained for each of the plurality of thicknesses of the X-ray beam 100 as described above, the work is difficult. Efficiency is greatly reduced.

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 radiation irradiation / detection apparatus which does not require a preliminary measurement for detecting an irradiation position and such a radiation irradiation / detection apparatus. To realize a radiation tomography apparatus provided with the same.

[0015]

[Means for Solving the Problems]

(1) A first 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 thickness. A radiation irradiating means for irradiating the radiation beam, and a plurality of radiation detecting elements having a dimension larger 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 detection element array to receive the radiation detection element array, at least at one end of the radiation detection element array, and each half of the radiation detection element array has a radiation receiving surface on opposite sides with respect to the center of the radiation detection element array in the thickness direction of the radiation beam. An even number of radiation detection elements, and the radiation detection element based on radiation detection signals of the even number of radiation detection elements. Characterized by comprising a an irradiation position detecting means for producing the irradiation position signal indicating the irradiation position of the radiation beam in Ray.

In the first invention, it is preferable that control means for controlling an irradiation position of the radiation beam in the radiation detecting element array based on the irradiation position signal is provided. It is preferable in terms of optimization.

(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 dimension width and the other has a relatively small dimension width. A radiation irradiating means for irradiating a radiation beam having a thickness, and a plurality of radiation detecting elements having a dimension larger than the thickness of the radiation beam in the direction of the thickness of the radiation beam, wherein a plurality of radiation detecting elements are arranged in the direction of the width of the radiation beam. A radiation detection element array that receives a beam of radiation, and a radiation detection element array provided at at least one end of the radiation detection element array and receiving half of the radiation on the opposite sides of the center of the radiation detection element array in the thickness direction of the radiation beam. An even-numbered radiation detecting element having a surface, and the radiation based on a radiation detection signal of the even-numbered radiation detecting element. Irradiation position detection means for generating an irradiation position signal indicating the irradiation position of the radiation beam on the line detection element array, and control means for controlling the irradiation position of the radiation beam on the radiation detection element array based on the irradiation position signal And a tomographic image generating means for generating a tomographic image of the radiation beam passage area based on the radiation detection signals of a plurality of views by the radiation detecting element array.

In the first invention or the second invention, it is preferable that the even-numbered radiation detecting elements are provided at both ends of the radiation detecting element array. It is preferable in that it can be appropriately detected.

Further, in the first invention or the second invention, there is provided a radiation intensity detecting means for generating a signal indicating the intensity of the radiation based on a sum of radiation detection signals of the even number of radiation detection elements. Is preferable in that a reference of the radiation detection signal is obtained.

Further, in the first invention or the second invention, the even-numbered radiation detecting elements are radiation detecting elements in the radiation detecting element array, and the radiation detecting elements in the direction of the thickness of the radiation beam. It is preferable that the radiation incident surfaces opposite to each other with respect to the center of the element array are shielded by a radiation shielding member in terms of utilizing the radiation detecting elements in the radiation detecting element array.

In the first and second aspects of the present invention, it is preferable that the radiation is X-rays because practical means concerning generation, detection, control, and the like are the most substantial.

(Function) In the first invention or the second invention, the radiation receiving surfaces of the even number of radiation detecting elements are opposite to each other by half with respect to the center of the radiation detecting element array in the direction of the thickness of the radiation beam. Therefore, on the opposite sides, the radiation detection signal changes differentially according to the position of the radiation beam in the thickness direction.

[0023]

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. As shown in FIG. 1, the apparatus includes a scanning gantry 2
And a photographing table 4 and an operation console 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 shaped by the collimator 22 into, for example, a fan-shaped X-ray beam, 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 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.

The collimator 22 is controlled by a collimator controller 30. The illustration of the connection relationship between the collimator 22 and the collimator controller 30 is omitted.

The above-described 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, for example, a computer
(computer) etc. To the central processing unit 60, a control interface (interface) 62 is connected. The scanning gantry 2 and the imaging table 4 are connected to the control interface 62.

The central processing unit 60 includes the control interface 6
2, the scanning gantry 2 and the imaging table 4 are controlled. The data acquisition unit 26, the X-ray controller 28, the collimator controller 30, and the rotation controller 34 in the scanning gantry 2 are controlled by the control interface 62. It should be noted that illustration of individual connections between these units and the control interface 62 is omitted. The central processing unit 60, the control interface 62, the collimator controller 30, and the collimator 22 are an example of an embodiment of a control unit in the present invention.

A data collection 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
4 temporarily stores the input data.

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 24 (i) are arranged in an arc to form a multi-channel X-ray detector. i is a channel number, for example, i = 1 to 1000. X-ray detector 2
FIG. 4 (i) is an example of an embodiment of the radiation detecting element in the present invention.

FIG. 3 shows the relationship among the X-ray tube 20, collimator 22, and 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 shaped into a fan-shaped X-ray beam 40 by the collimator 22 and are applied 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.

By making the body axis cross the fan surface of such an X-ray beam 40, for example, as shown in FIG.
Is placed in the X-ray irradiation space. X
A projection image of the subject 8 sliced by the line beam 40 is projected on the detector array 24. The thickness of the X-ray beam 40 at the isocenter of the subject 8 gives the slice thickness th of the subject 8. The slice thickness th is
It is determined by the X-ray 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 a direction to narrow the X-ray passing aperture, the slice thickness th of the projected image on the detector array 24 can be reduced. In addition, the collimator piece 2
The slice thickness th of the projected image on the detector array 24 can be increased by moving 20, 20 in the direction that widens the X-ray passage aperture.

By simultaneously moving the collimator pieces 220 and 222 with the slice thickness th set while maintaining the relative positional relationship, the X-rays on the detector array 24 are
The irradiation position of the line beam 40 in the thickness direction is controlled. Note that the irradiation position in the thickness direction is controlled 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.

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, an even number (in this case, two) of X-ray detecting elements 242 and 244 for detecting the irradiation position are provided. The X-ray detection elements 242 and 244 are an example of an embodiment of an even number of radiation detection elements in the present invention. Note that the detector array 24 provided with the X-ray detection elements 242 and 244 is provided.
Is outside the range where the transmission image of the subject is projected, whereby X-rays from the X-ray tube 20 are directly irradiated without transmitting through the subject 8.

The X-ray detecting elements 242 and 244 are configured such that the respective X-ray receiving surfaces, that is, the X-ray incident surfaces 250 and 270 are on opposite sides with respect to the center line 292 of the thickness of the detector array 24. .

Such X-ray detecting elements 242, 244
For example, the X-ray incidence surfaces of the two X-ray detection elements at the end of the detector array 24 are respectively connected to the X-ray shielding plates 252 and 252.
At 272, the opposite sides are half-covered. This is preferable because an X-ray detecting element having the same structure as other X-ray detecting elements in the detector array 24 can be used. The invention is not limited to this, and an X-ray detection element having a half dimension in the z direction may of course be used.

Since the X-ray detecting elements 242 and 244 have such X-ray incident surfaces 250 and 270, when the X-ray beam 40 having a thickness of T is displaced in the direction of the thickness (z direction), the X-ray detecting element 242 or 244 responds accordingly. Thus, the X-ray detection signals of the X-ray detection elements 242 and 244 change respectively.

FIG. 7 shows this state. FIG. 7 is a graph showing an example of the relationship between the moving distance z of the X-ray beam 40 and the X-ray detection signal i. The origin of the moving distance z is set at the position of the center line 292, and the moving direction is positive in the upward direction in FIG. The position of the X-ray beam 40 is represented by the position of the center of the thickness.

As shown in FIG. 7, when the X-ray beam 40 is at the position of z = 0, the X-ray detection signal of the X-ray detection element 242 indicates that the thickness T of the X-ray beam 40 By irradiating half, it becomes Im / 2. From this state, when the X-ray beam 40 moves in the positive direction, the X-ray detection signal gradually increases as the irradiation area of the X-ray beam 40 on the X-ray incident surface 250 increases. And z =
After the position of T / 2, the irradiation area becomes a constant value corresponding to the thickness T of the X-ray beam 40, so that the X-ray detection signal becomes Im.

When the X-ray beam 40 moves in the negative direction, the X-ray detection signal gradually decreases as the irradiation area of the X-ray beam 40 on the X-ray incident surface 250 decreases, and z
After the position of −T / 2, the X-ray beam 40 becomes 0 because it deviates from the X-ray incident surface 250.

Regarding the X-ray detecting element 244, since the X-ray incident surface 270 is on the opposite side of the X-ray incident surface 250 with respect to the center line 292, the movement of the X-ray beam 40 in the opposite direction is An X-ray detection signal similar to the above is obtained.

That is, the X-ray detection elements 242 and 244 obtain a pair of X-ray detection signals that change differentially with each other according to the change in the irradiation position of the X-ray beam 40. These X-ray detection signals are collected by the data collection unit 26 and input to the data collection buffer 64.

The central processing unit 60 calculates the difference between the pair of input signals input to the data collection buffer 64, and calculates X
An irradiation position detection signal of the line beam 40 is formed. The central processing unit 60 is an example of an embodiment of an irradiation position detection unit in the present invention.

As shown by a dashed line in FIG. 7, the irradiation position detection signal indicates that the irradiation position of the X-ray beam 40 is the detection array 24.
Becomes zero when the signal is on the center line 292 of the signal, and changes to positive or negative around 0 in accordance with positive or negative displacement in the z direction from this position.

That is, when the irradiation position of the X-ray beam 40 is on the center line 292 of the detection array 24, the irradiation detection signal becomes 0. Therefore, as in the conventional case, the correspondence between the irradiation position of the X-ray beam and the irradiation position detection signal is measured in advance, and when the irradiation position of the X-ray beam 40 is on the center line 292 of the detection array 24 based on the measurement. The operation of obtaining the value of the irradiation position detection signal is unnecessary.

Further, when the irradiation position of the X-ray beam 40 is on the center line 292 of the detection array 24, the value of the irradiation position detection signal is always 0 regardless of the thickness of the X-ray beam 40. It is not necessary to find the correspondence between the irradiation position of the X-ray beam 40 and the irradiation position detection signal for each beam thickness as in the conventional case. This greatly improves the workability of the adjustment.

The irradiation position detection signal may be obtained as a ratio of the X-ray detection signals of the X-ray detection elements 242 and 244. In this case, when the irradiation position of the X-ray beam 40 is on the center line 292 of the detection array 24, the irradiation position detection signal becomes 1 regardless of the thickness of the X-ray beam 40. It is unnecessary and very easy to adjust.

The central processing unit 60 recognizes the irradiation position in the thickness direction of the X-ray beam 40 on the detector array 24 based on such an irradiation position detection signal, and
The collimator 22 is controlled through the control interface 62 and the collimator controller 30 so that 0 is always irradiated to the center of the detector array 24 in the thickness direction, that is, the irradiation position detection signal becomes 0 (or 1).

Central processing unit 60, control interface 6
2. Collimator controller 30 and collimator 22
Is an example of an embodiment of the control means in the present invention. When the detector array 24 has a position adjusting mechanism, the position of the detector array 24 in the z direction may be controlled to control the irradiation position of the X-ray beam.

The central processing unit 60 calculates the sum of the X-ray detection signals of the X-ray detection elements 242 and 244, and obtains a reference signal indicating the intensity of the X-ray. The central processing unit 60 is an example of an embodiment of the radiation intensity detecting means in the present invention. FIG. 8 is a diagram for explaining that the sum of the X-ray detection signals of the X-ray detection elements 242 and 244 is equal to the reference signal.

The X-ray detecting element 246 adjacent to the X-ray detecting element 244 is also outside the projection range of the transmitted image of the subject 8,
It is an X-ray detection element for reference. The X-ray detection element 246 has an original X-ray incident surface 290 that is not shielded.

In the state where the X-ray beam 40 is irradiated, the sum of the X-ray irradiation areas (portions with horizontal hatching) in the X-ray detection elements 242 and 244 is the X-ray in the X-ray detection element 246 for reference. It is equal to the irradiation area (vertical hatched area).

Thus, the X-ray detecting elements 242, 24
The sum of the X-ray detection signals of No. 4 has a constant value irrespective of the irradiation position of the X-ray beam 40 in the z direction, as shown by the two-dot chain line in FIG. The X-ray detection signal gives a reference signal indicating the intensity of the X-ray. That is, the X-ray detection elements 242 and 244 are shared for detecting the irradiation position of the X-ray beam 40 and detecting the reference signal.

The central processing unit 60 includes the X-ray detecting element 24
The sum of the 2,244 X-ray detection signals is calculated by the X-ray detection element 246.
Is used as a reference signal together with the X-ray detection signal. In this way, the reference signal is divided into a plurality and the average value thereof is obtained, thereby obtaining a reference signal with little influence of noise.

At the other end of the detector array 24, there is provided a three-element structure similar to the X-ray detecting elements 242, 244, and 246.
Two X-ray detecting elements 242 ', 244', 246 'are provided. These X-ray detecting elements 242 ′, 244 ′,
The X-ray detection signal of 246 ′ is also used for controlling the irradiation position of the X-ray beam 40 and for reference as described above. Thus, at both ends of the detector array 24, X
By detecting and controlling the irradiation position of the X-ray beam, the parallelism between the X-ray beam 40 and the detector array 24 can be improved.

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 relation. 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.

The projection data collected in the data collection buffer 62 is subjected to X-ray intensity correction by the central processing unit 60 using the simultaneously collected reference signals, and based on the corrected projection data, the central processing unit The generation of a tomographic image, that is, image reconstruction is performed by 60. The central processing unit 60 is an example of an embodiment of a tomographic image generation unit according to the present invention. Image reconstruction is performed, for example, by using 1000-view projection data obtained by one rotation scan, for example, using filtered back-projection (filtered back-projection).
ection) method.

FIG. 9 schematically shows another example of the configuration of the X-ray detecting element for detecting the irradiation position. In this figure, the same parts as those in FIG.
Here, the X-ray detection elements 242 and 24 for detecting the irradiation position are used.
4, another X-ray detection element 248 is interposed. The X-ray shielding plate 252 is connected to the X-ray detection element 24.
The X-ray receiving surface of 2,244 is an integral shielding plate having a shape that covers the remaining portion while leaving the upper half and the lower half in the figure.

Since such an X-ray shielding plate 252 has an intermediate portion for one channel width that covers the X-ray detector 248, it is easy to maintain its integrity. This facilitates the work of attaching the X-ray shielding plate 252 to the X-ray detection elements 242, 244, 248. Note that X
The X-ray shielding plate 252 covers the entire X-ray incident surface of the X-ray detection element 248, so that the X-ray detection element 248 does not serve as an X-ray detector, and its output signal is not used.

FIG. 10 schematically shows another example of the configuration of the X-ray detecting element for detecting the irradiation position. In this figure, the same parts as those in FIG. Here, the X-ray shielding plate 252 is configured such that the edges 254 and 256 at the intermediate portion thereof are located on the X-ray receiving surface of the X-ray detecting element 248.

This facilitates the positioning of the X-ray shielding plate 252 in the direction in which the channels are arranged, and improves the processing accuracy of the edges 254 and 256 with the X-ray detecting elements 242 and 24.
4 is less likely to affect the X-ray receiving area.
In an actual detector array, the X-ray detection elements 242,
244 has a channel width of, for example, 2
Since it is about 1/0 to 1/30, providing a margin at the edges 254 and 256 in this manner is extremely effective in improving workability. Note that the output signal of the X-ray detection element 248 is not used.

In the above example, 2 is used for detecting the irradiation position.
Although an example in which four X-ray detecting elements are used has been described, four or more even-numbered X-ray detecting elements may be used, and half of the X-ray detecting elements may be provided on opposite sides with respect to the center line of the detection array. . This is preferable in that an irradiation position detection with better sensitivity or SNR (signal-to-noise ratio) is performed by synthesizing those X-ray detection signals.

The above description has been made of an example in which X-rays are used as radiation. However, 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.

[0071]

As described above in detail, according to the present invention, for detecting the irradiation position of the radiation beam, half of the even number of the radiation detecting element arrays each having a radiation receiving surface on the opposite side with respect to the center of the thickness of the radiation detecting element array. Since the radiation detecting element is used, it is possible to realize a radiation irradiating / detecting apparatus that does not require a preliminary measurement for detecting an irradiation position and a radiation tomography apparatus including such a radiation irradiating / detecting 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 graph showing an example of an irradiation position detection signal in the apparatus according to the embodiment of the present invention.

8 is a diagram showing that a sum of detection signals of a pair of X-ray detection elements is equal to a reference signal in the embodiment shown in FIG.

FIG. 9 is a schematic configuration diagram of a part of a detector array in an apparatus according to an example of an embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a part of a detector array in an apparatus according to an embodiment of the present invention.

FIG. 11 is a schematic diagram showing a conventional example of detecting an irradiation position of an X-ray beam in an X-ray detector.

[Explanation of symbols]

2 Scanning Gantry 20 X-ray Tube 22 Collimator 24 Detector Array 26 Data Collection Unit 28 X-ray Controller 30 Collimator Controller 32 Rotation Unit 34 Rotation Controller 4 Imaging Table 6 Operation Console 60 Central Processing Unit 62 Control Interface 64 Data Collection Buffer 66 Storage Device 68 display device 70 operating device 40 X-ray beam 8 subject 220, 222 collimator piece 24 (i), 242 to 248, 242 ′ to 246 ′ X
X-ray detector 250, 270, 290 X-ray incident surface 252, 272 X-ray shielding plate

Continued on the front page (72) Inventor Haruo Kuroji 127 GYokogawa Medical System Co., Ltd., 4-7 Asahigaoka, Hino-shi, Tokyo

Claims (2)

[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 detecting element array in which a plurality of radiation detecting elements having a dimension larger 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 and receiving the irradiation of the radiation beam; An even number of radiation detection elements provided at at least one end of the detection element array, each half having a radiation receiving surface on the opposite side with respect to the center of the radiation detection element array in the direction of the thickness of the radiation beam; Based on the radiation detection signals of the radiation detection elements, A radiation position detecting means for generating a radiation position signal indicating the radiation position of the beam. 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 detecting element array in which a plurality of radiation detecting elements having a dimension larger 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 and receiving the irradiation of the radiation beam; An even number of radiation detection elements provided at at least one end of the detection element array, each half having a radiation receiving surface on the opposite side with respect to the center of the radiation detection element array in the direction of the thickness of the radiation beam; Based on the radiation detection signals of the radiation detection elements, Irradiation position detection means for generating an irradiation position signal indicating the irradiation position of the beam; control means for controlling the irradiation position of the radiation beam in the radiation detection element array based on the irradiation position signal; and the radiation detection element array A tomographic image generating means for generating a tomographic image of a region through which the radiation beam passes based on the radiation detection signals of a plurality of views according to the above.