JP7240842B2 - Radiation diagnostic device, radiation detector, and collimator - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a radiodiagnostic apparatus, a radiation detector, and a collimator.

2. Description of the Related Art There is a radiodiagnostic apparatus that generates a radiographic image of an internal tissue of a subject by irradiating the subject with radiation. Examples of radiation diagnostic apparatuses include X-ray diagnostic apparatuses and X-ray CT (Computed Tomography) apparatuses. An X-ray diagnostic apparatus includes an X-ray source and an X-ray detector, and generates X-ray image data projecting the internal structure of a subject based on X-rays detected by the X-ray detector. Also, an X-ray CT apparatus includes an X-ray source and an X-ray detector, and generates CT image data and volume data of an axial tomography of a subject based on X-rays detected by the X-ray detector.

A radiation diagnostic apparatus such as an X-ray CT apparatus has a collimator on the X-ray incident side of an X-ray detector. The collimator removes the scattered X-rays incident on the X-ray detector by absorbing the scattered radiation component contained in the incident X-rays on the X-ray detector, that is, the scattered X-rays. Generally, the collimator comprises a plurality of absorbing walls arranged along the X-ray incident direction and made of a material capable of absorbing scattered X-rays.

In addition, heavy metals such as Mo (molybdenum) and W (tungsten) are used in large amounts as materials for the absorption walls that constitute the collimator. As a result, there is a problem that the manufacturing cost of the collimator increases significantly and the weight of the collimator increases.

JP 2008-168125 A

The problem to be solved by the present invention is to reduce the manufacturing cost and weight of the collimator.

The radiation diagnostic apparatus according to this embodiment includes an X-ray source that generates X-rays, an X-ray detector that detects the X-rays and generates an electric signal corresponding to the X-rays, and an X-ray detector that detects the X-rays. a collimator provided on the incident side and made up of an absorbing wall that absorbs the scattered X-rays. The absorbing wall includes a plurality of absorbing portions arranged along the incident direction of X-rays. The plurality of absorbing portions are arranged at uneven intervals along the incident direction of X-rays.

FIG. 1 is a schematic diagram showing the configuration of an X-ray CT apparatus, which is an example of a radiodiagnostic apparatus according to this embodiment. FIG. 2 is a perspective view showing the appearance of an X-ray detector provided with a collimator according to the embodiment; FIG. 3 is a front view showing a first structural example of the collimator according to the embodiment; FIG. 4 is a front view showing a second structural example of the collimator according to the embodiment; FIG. 5 is a front view showing a third structural example of the collimator according to the embodiment; FIG. 6 is a front view showing a fourth structural example of the collimator according to the embodiment; FIG. 7 is a front view showing a fifth structural example of the collimator according to the embodiment; FIG. 8 is a side view showing a structural example of the collimator according to the embodiment; FIG. 9 is a side view showing a structural example of the collimator according to the embodiment; FIG. 10 is a side view showing a structural example of a collimator according to this embodiment; FIG. 11 is a front view showing a sixth structural example of the collimator according to the present embodiment;

A radiodiagnostic apparatus, a radiation detector, and a collimator according to this embodiment will be described with reference to the accompanying drawings.

A radiation diagnostic apparatus according to this embodiment is an apparatus that includes a collimator for removing scattered radiation on the X-ray incident side of a radiation detector. Examples of radiation diagnostic apparatuses include X-ray diagnostic apparatuses and X-ray CT apparatuses. A case where the radiation diagnostic apparatus is an X-ray CT apparatus will be described below.

In addition, the data acquisition method by the X-ray CT apparatus includes a rotation/rotation (RR: Rotate/Rotate) method in which the X-ray source and the X-ray detector rotate around the subject as a unit, and a ring-shaped method. There are various schemes such as the Stationary/Rotate (SR) scheme in which a large number of detector elements are arrayed in the X-ray tube and only the X-ray tube rotates around the subject. The present invention can be applied to any method. In the following, the X-ray CT apparatus according to the present embodiment will be described by taking as an example a case where the rotation/rotation method of the third generation, which is currently the mainstream, is adopted.

FIG. 1 is a schematic diagram showing the configuration of an X-ray CT apparatus, which is an example of a radiodiagnostic apparatus according to this embodiment.

FIG. 1 shows an X-ray CT apparatus 1A, which is an example of a radiodiagnostic apparatus 1 according to this embodiment. The X-ray CT apparatus 1A includes a gantry device 10, a bed device 30, and a console device 40. The gantry device 10 and the bed device 30 are installed in an examination room. The gantry device 10 collects X-ray detection data regarding a subject (for example, a patient) P placed on the bed device 30 . On the other hand, the console device 40 is installed in a control room adjacent to the examination room, generates multidirectional projection data based on multidirectional detection data, and reconstructs a CT image based on the multidirectional projection data. indicate.

The gantry 10 includes an X-ray source (for example, an X-ray tube) 11, an X-ray detector 12, a rotating frame 13, an X-ray high voltage device 14, a control device 15, a wedge 16, an aperture 17, a data acquisition circuit (DAS: Data Acquisition System) 18, and a collimator 19 (shown in FIG. 2).

The X-ray tube 11 is provided on a rotating frame 13 . The X-ray tube 11 is a vacuum tube that emits thermal electrons from a cathode (filament) toward an anode (target) by applying a high voltage from an X-ray high voltage device 14 . In the present embodiment, a so-called multi-tube X-ray CT apparatus in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating ring is applied to the single-tube X-ray CT apparatus. is also applicable.

Note that the X-ray source that generates X-rays is not limited to the X-ray tube 11 . For example, instead of the X-ray tube 11, a focus coil for converging the electron beam generated from the electron gun, a deflection coil for electromagnetic deflection, and a target surrounding half the circumference of the patient P and generating X-rays by collision of the deflected electron beam. X-rays may be generated by a fifth generation method including rings.

The X-ray detector 12 is an example of a radiation detector, and is provided on the rotating frame 13 so as to face the X-ray tube 11 . The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and outputs detection data corresponding to the X-ray dose to the DAS 18 as electrical signals. The X-ray detector 12 has, for example, a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one circular arc around the focal point of the X-ray tube. The X-ray detector 12 has, for example, a structure in which a plurality of X-ray detection element arrays each having a plurality of X-ray detection elements arranged in the channel direction are arranged in the slice direction (column direction, row direction).

Here, a collimator 19 (illustrated in FIG. 2) is provided on the X-ray incident side of the X-ray detector 12 . The collimator 19 is also called a grid, and removes scattered X-rays incident on the X-ray detector 12 by absorbing scattered X-rays among incident X-rays. The collimator 19 includes absorption walls (absorption walls G and H shown in FIG. 3, etc.) made of a material capable of absorbing scattered X-rays.

Also, the X-ray detector 12 is an indirect conversion type detector having a scintillator array 51 and a photosensor array 52 (shown in FIG. 2). The scintillator array 51 has a plurality of scintillators, and each scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays. The photosensor array 52 has a function of converting the amount of light from the scintillator array 51 into an electrical signal, and has photosensors such as a photomultiplier tube (PMT).

The rotating frame 13 supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. The rotating frame 13 is an annular frame that rotates the X-ray tube 11 and the X-ray detector 12 together under the control of a control device 15, which will be described later. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 may further include an X-ray high-voltage device 14 and a DAS 18 to support them.

In this manner, the X-ray CT apparatus 1A rotates around the patient P the rotating frame 13 that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. , 360 degrees of detection data of the patient P are collected. Note that the CT image reconstruction method is not limited to the full-scan reconstruction method using detection data for 360°. For example, the X-ray CT apparatus 1A may employ a half-reconstruction method for reconstructing a CT image based on the detected data for half the circumference (180°) plus the fan angle.

The X-ray high voltage device 14 has electric circuits such as a transformer and a rectifier. The X-ray high voltage device 14 is controlled by a high voltage generator (not shown) having a function of generating a high voltage to be applied to the X-ray tube 11 under the control of the control device 15, which will be described later, and the control device 15, which will be described later. , there is an X-ray control device (not shown) for controlling the output voltage according to the X-rays emitted by the X-ray tube 11 . The high voltage generator may be of a transformer type or an inverter type. The X-ray high-voltage device 14 may be provided on a rotating frame 13 described later, or may be provided on the fixed frame side of the gantry device 10 .

The controller 15 has processing circuitry and memory, and drive mechanisms such as motors and actuators. The configuration of the processing circuit and memory is the same as that of the processing circuit 44 and memory 41 of the console device 40, which will be described later, and therefore the description thereof is omitted.

The control device 15 has a function of receiving an input signal from an input interface (not shown) attached to the console device 40 or the gantry device 10 and controlling the operations of the gantry device 10 and the bed device 30 . For example, the control device 15 receives an input signal and performs control to rotate the rotating frame 13 , control to tilt the gantry device 10 , and control to operate the bed device 30 and the tabletop 33 . Note that the control for tilting the gantry device 10 is performed by the control device 15 based on the tilt angle (tilt angle) information input through the input interface attached to the gantry device 10, so as to rotate the rotating frame 13 about an axis parallel to the X-axis direction. This is achieved by rotating the Note that the control device 15 may be provided in the gantry device 10 or may be provided in the console device 40 .

In addition, the control device 15 controls the angle of the X-ray tube 11 and the operation of a wedge 16 and a diaphragm 17, which will be described later, based on imaging conditions input from an input interface attached to the console device 40 or the gantry device 10. .

A wedge 16 is provided on the rotating frame 13 so as to be arranged on the X-ray emission side of the X-ray tube 11 . Wedge 16 is a filter for adjusting the dose of X-rays emitted from X-ray tube 11 under the control of controller 15 . Specifically, the wedge 16 is a filter that transmits and attenuates the X-rays emitted from the X-ray tube 11 so that the X-rays emitted from the X-ray tube 11 to the patient P have a predetermined distribution. is. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter machined from aluminum to have a predetermined target angle and a predetermined thickness.

The diaphragm 17 is also called a slit, and is provided on the rotating frame 13 so as to be arranged on the X-ray emission side of the X-ray tube 11 . The aperture 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16 under the control of the control device 15, and forms an X-ray irradiation aperture by combining a plurality of lead plates or the like.

A DAS 18 is provided on the rotating frame 13 . Under the control of the controller 15, the DAS 18 includes an amplifier that amplifies the electrical signal output from each X-ray detection element of the X-ray detector 12, and converts the electrical signal into a digital signal under the control of the controller 15. It has an A/D (Analog to Digital) converter for converting into a signal, and generates detection data after amplification and digital conversion. Detection data generated by DAS 18 is transferred to console device 40 .

Here, the detection data generated by the DAS 18 is transmitted from a transmitter having a light emitting diode (LED) provided on the rotating frame 13 by optical communication to a non-rotating portion of the gantry 10, for example, a photo sensor provided on a fixed frame (not shown). It is sent to a receiver with a diode and forwarded to the console device 40 . The method of transmitting the detection data from the rotating frame 13 to the non-rotating portion of the gantry 10 is not limited to the optical communication described above, and any method of non-contact data transmission may be employed. A fixed frame (not shown) is a frame that rotatably supports the rotating frame 13 .

The bed device 30 includes a base 31 , a bed driving device 32 , a top plate 33 and a support frame 34 . The bed device 30 is a device on which the patient P to be scanned is placed and which is moved under the control of the control device 15 .

The base 31 is a housing that supports the support frame 34 so as to be movable in the vertical direction (y-axis direction). The bed driving device 32 is a motor or actuator that moves the table 33 on which the subject P is placed in the longitudinal direction (z-axis direction) of the table 33 . The top plate 33 provided on the upper surface of the support frame 34 is a plate having a shape on which the patient P can be placed.

Note that the bed driving device 32 may move the support frame 34 in addition to the top plate 33 in the long axis direction (z-axis direction) of the top plate 33 . Further, the bed driving device 32 may move the base 31 of the bed device 30 together. When the present invention is applied to standing CT, a method of moving a patient moving mechanism corresponding to the top plate 33 may be used. In addition, when performing imaging involving a relative change in the positional relationship between the imaging system of the gantry device 10 and the tabletop 33, such as helical scan imaging or scanography for positioning, etc., the relative change in the positional relationship may be performed by driving the top plate 33, may be performed by running the fixed frame of the gantry device 10, or may be performed by a combination thereof.

In this embodiment, the rotation axis of the rotating frame 13 in the non-tilt state or the longitudinal direction of the top plate 33 of the bed device 30 is the z-axis direction, and the axial direction perpendicular to the z-axis direction and horizontal to the floor surface is are defined as the x-axis direction, the direction perpendicular to the z-axis direction, and the direction perpendicular to the floor surface as the y-axis direction.

Console device 40 includes memory 41 , display 42 , input interface 43 , and processing circuitry 44 . In the following description, it is assumed that the console device 40 executes all functions with a single console, but these functions may be executed with a plurality of consoles.

The memory 41 is, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like, and has a configuration including a recording medium readable by a processor.

Detection data generated by the X-ray CT apparatus 1A and projection data and reconstructed image data, which will be described later, may be stored in the memory 41 . The detection data, projection data, and reconstructed image data generated by the X-ray CT apparatus 1A are sent to an external device such as an image server connectable to the X-ray CT apparatus 1A via a network such as a LAN (Local Area Network). It may be stored in a storage device. Similarly, part or all of the programs and data in the recording medium of the memory 41 may be downloaded by communication via a network, or given to the memory 41 via a portable storage medium such as an optical disk. good.

The display 42 displays various information. For example, the display 42 outputs a medical image (CT image) generated by the processing circuit 44, a GUI (Graphical User Interface) for receiving various operations from the user, and the like. For example, the display 42 is a liquid crystal display, a CRT (Cathode Ray Tube) display, an OLED (Organic Light Emitting Diode) display, or the like.

The input interface 43 receives various input operations from the user, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 44 . For example, the input interface 43 receives setting information from the user, such as acquisition conditions for acquiring data, reconstruction conditions for reconstructing CT images, and image processing conditions for image processing of CT images. For example, the input interface 43 is implemented by input devices such as a mouse, keyboard, trackball, switch, button, joystick, and the like.

The processing circuit 44 is a processor that reads and executes programs stored in the memory 41 to control the overall operation of the X-ray CT apparatus 1A. The processing circuit 44 performs preprocessing such as correction processing on the detection data output from the DAS 18 to generate projection data. The processing circuit 44 also performs reconstruction processing on the projection data to generate CT image data of the axial tomography. Furthermore, the processing circuit 44 generates volume data based on the CT image data, thereby generating image data of an arbitrary tomogram (MPR: Multi-Planar Reconstruction) and projection image data viewed from an arbitrary direction as CT image data. do. Volume data is data having CT value distribution information in a three-dimensional space. Projection image data is obtained by subjecting volume data to volume rendering processing or surface rendering processing.

Next, the structure of the collimator 19 according to this embodiment provided in the X-ray CT apparatus 1A according to this embodiment will be specifically described.

2A and 2B are perspective views showing the appearance of the collimator 19. FIG.

As shown in FIGS. 2A and 2B, the collimator 19 is arranged on the X-ray incident side of the X-ray detector 12 . FIG. 2A shows a collimator in which a plurality of absorbing walls extending in the column direction are arranged along the channel direction, and a plurality of absorbing walls extending along the channel direction are arranged along the column direction. , denote a two-dimensional collimator. On the other hand, FIG. 2B shows a collimator in which a plurality of absorbing walls extending in the column direction are arranged along the channel direction, that is, a one-dimensional collimator. The collimator 19 according to this embodiment can be applied to both a one-dimensional collimator and a two-dimensional collimator, but in the following description, the case of the one-dimensional collimator shown in FIG.

FIG. 3 is a front view showing a first structural example of the collimator 19. As shown in FIG.

As shown in FIG. 3, the collimator 19 is provided on the X-ray incident side of the scintillator array 51 . The scintillator array 51 includes a plurality of elements 51a (corresponding to X-ray detection elements) in the channel direction. Moreover, the collimator 19 arranges a plurality of absorption walls along the channel direction so as to separate the plurality of elements 51a in the channel direction. Each absorbing wall is arranged so that its side faces are along the X-ray incident direction. Each absorbing wall absorbs scattered radiation. FIG. 3 shows two absorption walls G and H adjacent in the channel direction among the plurality of absorption walls.

The absorbing wall G includes n (n is an integer equal to or greater than 3) absorbing portions G1 to Gn arranged along the X-ray incidence direction, and non-absorbing portions between the absorbing portions. An absorption wall H adjacent to the absorption wall G in the channel direction has n absorption portions H1 to Hn arranged along the X-ray incidence direction. The n absorption portions G1 to Gn have intervals (pitch) therebetween and are arranged at unequal intervals along the X-ray incident direction. Between each of the n absorbing portions G1 to Gn, a transmitting member such as an adhesive is arranged as a non-absorbing portion that transmits X-rays. The n absorption portions H1 to Hn are similar to the n absorption portions G1 to Gn.

In the example shown in FIG. 3, the n absorption portions G1 to Gn arranged in the absorption wall G of the collimator 19 are spaced apart from each other in the direction of X-ray incidence so as to remove at least primary X-rays that are about to enter the scintillator array 51 . placed along the In order to remove the primary X-rays, the n absorbers G1 to Gn are arranged so that the distance between them gradually decreases from the absorber G1 toward the absorber Gn. In other words, the n absorption portions G1 to Gn are arranged so as to be sparse on the side closer to the X-ray tube 11 than on the side closer to the scintillator array 51 in the X-ray incident direction.

Since the plurality of absorbing portions G1 to Gn arranged in the absorbing wall G have such an arrangement, gaps are formed by intervals between the n absorbing portions H1 to Hn arranged in the adjacent absorbing walls H. The primary X-rays L1 to Ln passing through the (non-absorbing portion) can be absorbed without omission. In addition, since the plurality of absorbers G1 to Gn of the absorber wall G have such an arrangement, the use of materials such as molybdenum and tungsten can be reduced by about 10% compared to a conventional collimator with non-spaced absorber walls. can be reduced to In addition to the absorption wall G, the plurality of absorption portions of other absorption walls provided in the channel direction can also be arranged in the same manner as the absorption wall G.

Note that it is not essential that all of the plurality of absorption walls provided in the channel direction are arranged in the same manner. For example, when the absorption wall H shown in FIG. On the other hand, if there is another absorption wall on the right side of the absorption wall H shown in FIG. and does not reach the absorption wall G. Therefore, in the plurality of absorption walls in the channel direction, the length and number of intervals between the plurality of absorption portions can be changed according to the position of each absorption wall in the channel direction.

According to the first structural example of the collimator 19 shown in FIG. 3, the production cost and weight of the collimator can be suppressed while maintaining the function of removing scattered X-rays.

Here, the structure of the collimator 19 shown in FIG. 3 may be partially modified. For example, in order to improve the absorption rate of secondary X-rays from the absorbing wall, the material of the absorbing wall may be changed along the channel direction (shown in FIG. 4), or the material of the absorbing portions may be is changed along the X-ray incident direction (shown in FIG. 5), or the thickness of the absorption wall is changed along the X-ray incident direction (concavo-convex configuration) (shown in FIG. 6). ). As a result, the second material can absorb the secondary X-rays emitted by the first material and having energy lower than the energy of the characteristic X-rays having relatively high intensity. X-ray absorption rate can be improved.

FIG. 4 is a front view showing a second structural example of the collimator 19. As shown in FIG.

As shown in FIG. 4, the collimator 19 employs the structure of a plurality of absorbing portions with intervals shown in FIG. 3, while changing the material of the absorbing portions along the channel direction. For example, the collimator 19 uses a first material (for example, molybdenum) as the material of the n absorption portions G1 to Gn arranged in the absorption wall G, and the n absorption portions H1 to Hn arranged in the absorption wall H. can be the second material (eg, tungsten).

In addition, the collimator 19 shown in FIG. 4 is arranged between adjacent absorption walls in the channel direction (one absorption wall and one absorption wall adjacent to that absorption wall, and a set consisting of a plurality of absorption walls). , and the set of absorbent walls adjacent to the set) may be of different materials. For example, when using two kinds of materials, it is preferable that the materials of the plurality of absorbent walls arranged along the channel direction are alternately arranged. Further, for example, when three kinds of materials are used, it is preferable that the materials of the plurality of absorption walls arranged along the channel direction are alternately changed.

According to the second structural example of the collimator 19 shown in FIG. 4, in addition to the effect of the first example of the collimator 19 shown in FIG. 3, the absorptivity of secondary X-rays can be improved.

FIG. 5 is a front view showing a third structural example of the collimator 19. As shown in FIG.

As shown in FIG. 5, the collimator 19 employs the structure of multiple absorbers with intervals shown in FIG. It is. For example, the collimator 19 combines the material of the absorption portions G1, G3, . . . arranged in the absorption wall G and the material of the absorption portions H1, H3, . ), and the material of the absorption portions G2, G4, . . . arranged in the absorption wall G and the material of the absorption portions H2, H4, . be able to.

Note that the collimator 19 shown in FIG. 5 has two absorption portions adjacent to each other in the X-ray incident direction (one absorption portion and one absorption portion adjacent to that absorption portion, and a plurality of absorption portions). A set and a set of absorbent parts adjacent to the set) may be made of different materials. For example, when two kinds of materials are used, it is preferable that the materials of a plurality of absorbing portions arranged along the X-ray incident direction are alternately replaced. Further, for example, when three kinds of materials are used, it is preferable that the materials of the plurality of absorbing portions arranged along the X-ray incident direction are alternated in order. Moreover, although different materials are switched in the same order between adjacent absorbent walls, different materials may be switched in different orders.

According to the third structural example of the collimator 19 shown in FIG. 5, in addition to the effect of the first example of the collimator 19 shown in FIG. 3, the absorptivity of secondary X-rays can be improved.

FIG. 6 is a front view showing a fourth structural example of the collimator 19. As shown in FIG.

As shown in FIG. 6, the collimator 19 employs the structure of a plurality of absorbing portions with the intervals shown in FIG. In this case, an absorbing portion thinner than the absorbing portion is arranged in the channel direction. That is, the non-absorbing portions between the absorbing portions adjacent in the X-ray incident direction shown in FIG. 3 are replaced with thin absorbing portions.

For example, the collimator 19 arranges an absorbing portion g1 thinner than the absorbing portion Gn in the channel direction between the absorbing portions G1 and G2 arranged in the absorbing wall G. As shown in FIG. Further, for example, the collimator 19 arranges an absorbing portion h1 thinner than the absorbing portion Hn in the channel direction between the absorbing portions H1 and H2 arranged in the absorbing wall H. As shown in FIG. Note that the thin absorbing portion is not limited to being thinner than the absorbing portion Gn in the channel direction. The thin absorbing portion may be thinner than the absorbing portion Gn in the column direction, or may be thinner than the absorbing portion Gn in the channel direction and the column direction.

According to the fourth structural example of the collimator 19 shown in FIG. 6, in addition to the effects of the first example of the collimator 19 shown in FIG.

Further, in the collimator 19A in which a plurality of absorbing portions of each absorbing wall are arranged at equal intervals, between the absorbing portions adjacent in the X-ray incident direction, the material is the same as that of the absorbing portions, and there is more than the absorbing portion in the channel direction. A thin absorption part may be arranged. FIG. 7 shows this case. FIG. 7 is a modification of FIG. By adopting such a configuration, the non-absorbing portion, that is, the adhesive layer can be made unnecessary, similarly to the effect of FIG.

Next, the structure of the absorption wall of the collimator 19 shown in FIGS. 3 to 6 as viewed from the side will be described with reference to FIGS. 8 and 9. FIG. The technical ideas shown in FIGS. 8 and 9 can also be applied to the structure of the absorption wall of the collimator 19A shown in FIG.

FIG. 8 is a side view showing a structural example of the collimator 19. As shown in FIG.

The structure of the absorbing walls in the column direction of the collimator 19 shown in FIG. 3 will be described with reference to FIG. The structure of the absorbing walls in the row direction of the collimator 19 shown in FIGS. 4 to 6 is the same.

As shown in FIG. 8, the collimator 19 has absorption walls arranged across the plurality of elements 51a in the column direction. FIG. 8 shows the absorption wall G shown in FIG. As described with reference to FIG. 3, the n absorption portions G1 to Gn are arranged so that they are sparse on the side closer to the X-ray tube 11 than on the side closer to the scintillator array 51 in the X-ray incident direction. placed.

9A and 9B are side views showing structural examples of the collimator 19. FIG. FIG. 9B is an enlarged view of region R shown in FIG. 9A.

The structure in the column direction of the collimator 19 shown in FIG. 3 will be described with reference to FIGS. 9(A) and 9(B). The structure of the absorbing walls in the row direction of the collimator 19 shown in FIGS. 4 to 6 is the same.

As shown in FIG. 9A, the collimator 19 has a plurality of absorption walls arranged along the row direction so as to separate the plurality of elements 51a in the row direction. Also, the collimator 19 arranges a plurality of absorbing walls such that the order of the absorbing portions and the non-absorbing portions is staggered along the column direction. For example, the order of the absorbent portions G1, G2, . . . and the non-absorbent portions of the absorbent wall G and the order of the absorbent portions J1, J2, .

As shown in FIG. 9B, the absorbent wall G has a configuration in which the absorbent portions G1 of the absorbent wall G are supported by the absorbent portions J1 of the absorbent walls J adjacent in the column direction. With such a configuration, each absorption wall of the collimator 19 can be easily produced by a 3D printer or the like.

The column-direction structure of the collimator 19 in which the plurality of absorbing portions of each absorbing wall are arranged at unequal intervals has been described with reference to FIGS. 9A and 9B. However, it is not limited to that case. In a collimator 19A (for example, the collimator 19A shown in FIG. 7) in which a plurality of absorbing portions of each absorbing wall are arranged at regular intervals, the order of the absorbing portions and the non-absorbing portions is staggered along the column direction. In some cases, an absorption wall of FIG. 10 shows this case. FIG. 10 is a modification of FIG. 9(A). In the collimator 19A shown in FIG. 10 as well, the absorbing portion G1 of the absorbing wall G is supported by the absorbing portion J1 of the adjacent absorbing wall J as shown in FIG. 9B. With such a configuration, each absorbing wall of the collimator 19A can be easily produced by a 3D printer or the like, similar to the effect of FIGS. 9A and 9B.

So far, the structure of the one-dimensional collimator (illustrated in FIG. 2B) in which a plurality of absorbing walls are arranged along the channel direction has been described. It can also be applied to a two-dimensional collimator (illustrated in FIG. 2(A)) in which a plurality of absorbing walls are arranged along the length of the collimator. In the case of a two-dimensional collimator, only a plurality of absorbing walls are arranged in the column direction in any of FIGS. 3 to 7 (including any combination of FIGS. 3 to 7 and any of FIGS. 8 to 10) Alternatively, both the plurality of absorption walls in the channel direction and the plurality of absorption walls in the column direction may be arranged in any of FIGS. (including combinations of any of the above) may be used.

Also, as an example in which the plurality of absorption portions of each absorption wall are arranged at unequal intervals along the X-ray incidence direction, the structure in which the intervals between the plurality of absorption portions expand or narrow with regularity has been described so far. . However, it is not limited to that case. 3, when considering that the scintillator array 51 has a large number of elements 51a (corresponding to X-ray detection elements) in the channel direction, there is no need to provide an absorption portion on the lower side of each absorption wall. . Specifically, the scattered rays that are going to be incident on the detection surface of the element 51a of the scintillator array 51 at an acute angle from the side of the absorption wall H are scattered by the absorption wall farther than the absorption wall H (the absorption wall on the right side of the absorption wall H in FIG. 3). wall), it is not necessary to arrange an absorption part in the absorption wall H at the incident position of the scattered radiation.

11A and 11B are front views showing a sixth structural example of the collimator 19. FIG.

FIG. 11(A) shows scattered rays from the right side of the element 51a that are considered when the element 51a of the scintillator array 51 is used as a reference. The absorption wall H arranges an absorption portion at a position where it absorbs scattered rays (double-dotted dashed lines in the figure) that are not absorbed by the adjacent absorption wall K. FIG.

On the other hand, the scattered rays that are about to enter the detecting surface of the element 51a at an acute angle are absorbed by the absorbing walls K, S, . Therefore, it is not necessary to dispose an absorbing portion on the lower side W of the absorbing wall H where the extended line of the scattered rays collides. As for the absorbing walls K, S, .

From FIG. 11(A), it can be seen that the absorption wall H closer to the element 51a serving as a reference requires many absorption parts to be arranged in its lower part, while the required absorption parts decrease as the distance from the element 51a increases. . In FIG. 11A, only the right side of the reference element 51a is illustrated, but the same applies to the left side of the element 51a.

FIG. 11(B) shows scattered rays from the right side of the element 51b of the scintillator array 51 that are considered when the element 51b is used as a reference. Element 51b is adjacent to element 51a in FIG. 11(A). The absorbing wall K has an absorbing portion arranged at a position where it absorbs scattered rays (double-dotted dashed lines in the drawing) that are not absorbed by the adjacent absorbing wall S. FIG.

On the other hand, the scattered rays that are about to enter the detection surface of the element 51b at an acute angle are absorbed by the absorption walls S, T, . Therefore, in the absorbing wall K, it is not necessary to dispose an absorbing portion on the lower side W where the extended line of the scattered radiation collides. As for the absorbing walls S, T, .

From FIG. 11(B), it can be seen that while the absorption wall K near the reference element 51b requires many absorption parts to be arranged in its lower part, the required absorption parts decrease as the distance from the element 51b increases. . In FIG. 11B, only the right side of the reference element 51b is illustrated, but the same applies to the left side of the element 51b.

Then, the position of the absorbing portion required for each absorbing wall is determined while shifting the reference elements 51a, 52b, . . . Calculate the position.

As a result, it is possible to greatly omit the installation of the absorbing section on the lower side of the absorbing wall. In particular, it is possible to greatly omit the installation of the absorbers at the ends of the collimator 19 compared to the center in the channel direction.

According to at least one embodiment described above, the manufacturing cost and weight of the collimator can be suppressed.

In the above embodiment, the term "processor" includes, for example, a dedicated or general-purpose CPU (Central Processing Unit) and GPU (Graphics Processing Unit), as well as an application specific integrated circuit (ASIC) and shall mean a circuit such as a programmable logic device. Programmable logic devices include, for example, Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs). The processor implements various functions by reading and executing programs stored in the storage medium.

Further, in the above embodiments, an example of a case where a single processor of the processing circuit realizes each function is shown, but a processing circuit is configured by combining a plurality of independent processors, and each processor realizes each function. Also good. Further, when a plurality of processors are provided, a storage medium for storing programs may be provided individually for each processor, or a single storage medium may collectively store programs corresponding to the functions of all processors. Also good.

In the above embodiment, the scintillator array 51 and the photosensor array 52 are referred to as "radiation detector" and "X-ray detector". However, the collimator 19, scintillator array 51, and photosensor array 52 may also be referred to as "radiation detector" and "X-ray detector."

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Radiological diagnostic apparatus 1A... X-ray CT apparatus 11... X-ray source (X-ray tube)
12... X-ray detectors 19, 19A... Collimator 51... Scintillator array 52... Optical sensor arrays G, H... Absorbing walls G1 to Gn, H1 to Hn... Absorbing parts

Claims (11)

an X-ray source that generates X-rays;
an X-ray detector that detects the X-rays and generates an electrical signal corresponding to the X-rays;
a collimator provided on the X-ray incident side of the X-ray detector and made of an absorbing wall that absorbs scattered X-rays;
The absorption walls extend in the row direction of the X-ray detectors, and are arranged in plurality along the channel direction of the X-ray detectors,
The absorbing wall includes a plurality of absorbing portions arranged along the incident direction of the X-rays, and the order of the absorbing portions and the non-absorbing portions of the plurality of absorbing portions is staggered along the column direction. with configuration,
The plurality of absorbing parts are arranged at uneven intervals along the direction of incidence of the X-rays,
The absorbent portion of the first absorbent wall as the absorbent wall supports the absorbent portion of the second absorbent wall adjacent to the first absorbent wall as the absorbent wall,
Radiological diagnostic equipment. The plurality of absorbing parts are arranged so as to be sparse on the side closer to the X-ray source than on the side closer to the X-ray detector in the direction of incidence of the X-rays.
The radiation diagnostic apparatus according to claim 1 . A transmitting member that transmits the X-rays is arranged between the plurality of absorbing parts.
The radiodiagnostic apparatus according to claim 1 or 2 . Between the plurality of absorption portions, an absorption portion made of the same material as the plurality of absorption portions and having a thinner thickness than the plurality of absorption portions is arranged.
The radiodiagnostic apparatus according to claim 1 or 2 . The absorption walls extend in the row direction of the X-ray detectors, are arranged in plurality along the channel direction of the X-ray detectors, and extend in the channel direction of the X-ray detectors, and a plurality of arranged along the column direction of the X-ray detector,
The radiodiagnostic apparatus according to claim 1 or 2 . The material of the plurality of absorbent walls arranged along the channel direction is changed along the channel direction, and/or the material of the plurality of absorbent walls arranged along the row direction is changed. , configured to change along the column direction,
The radiation diagnostic apparatus according to claim 5 . With respect to the plurality of absorbing walls extending in the row direction, the order of each absorbing portion and the non-absorbing portion of the plurality of absorbing portions is staggered along the row direction,
With respect to the plurality of absorbent walls extending in the channel direction, the order of each absorbent portion and the non-absorbent portion of each absorbent portion of the plurality of absorbent portions is staggered along the channel direction,
The radiation diagnostic apparatus according to claim 5 . The absorbent portion of the first absorbent wall as the absorbent wall supports the absorbent portion of the second absorbent wall adjacent to the first absorbent wall as the absorbent wall,
The radiation diagnostic apparatus according to claim 7 . The material of the plurality of absorbing parts arranged along the incident direction of the X-ray is changed along the incident direction of the X-ray,
The radiation diagnostic apparatus according to any one of claims 1 to 8 . A radiation detector comprising a collimator comprising an absorbing wall that absorbs scattered X-rays,
The absorption walls extend in the row direction of the radiation detectors, and are arranged in plurality along the channel direction of the radiation detectors,
The absorbing wall includes a plurality of absorbing portions arranged along an incident direction of X-rays from the X-ray source, and the order of each absorbing portion and the non-absorbing portion of the plurality of absorbing portions is in the column direction. With staggered configurations along,
The plurality of absorbing parts are arranged at uneven intervals along the direction of incidence of the X-rays,
The absorbent portion of the first absorbent wall as the absorbent wall supports the absorbent portion of the second absorbent wall adjacent to the first absorbent wall as the absorbent wall,
radiation detector. A collimator comprising an absorbing wall that absorbs scattered X-rays,
The absorption walls extend in the row direction of the radiation detectors, and are arranged in plurality along the channel direction of the radiation detectors,
The absorbing wall includes a plurality of absorbing portions arranged along an incident direction of X-rays from the X-ray source, and the order of each absorbing portion and the non-absorbing portion of the plurality of absorbing portions is arranged in the row direction. With staggered configurations along,
The plurality of absorbing parts are arranged at uneven intervals along the direction of incidence of the X-rays,
The absorbent section of the first absorbent wall as the absorbent wall supports the absorbent section of the second absorbent wall adjacent to the first absorbent wall as the absorbent wall,
collimator.

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