JP3842195B2 - X-ray CT system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray CT apparatus, and more particularly to an X-ray CT apparatus having a magnification changing function.
[0002]
[Prior art]
The X-ray CT apparatus is an apparatus that rotates an X-ray beam that passes through a subject and reconstructs a tomographic image or a three-dimensional image of the subject based on data obtained thereby. In addition to being used for diagnosing human diseases, the X-ray CT apparatus is also used for measuring animals and other objects other than the human body for the purpose of research and experiments. For example, in a pharmaceutical company, an X-ray CT apparatus is used for verification of animal experiments. In this case, examples of the subject include small animals such as guinea pigs, rats, mice, and hamsters. Conventionally, when performing X-ray diagnosis of a small animal using an X-ray CT apparatus, for example, the subject is simply placed on a horizontal bed.
[0003]
The following Patent Document 1 discloses a veterinary X-ray imaging apparatus (so-called X-ray imaging apparatus) provided with a table having a simple V-groove on which an animal such as a dog is placed. In this device, the front and rear of the small animal are open. Patent Document 2 below discloses an industrial X-ray CT apparatus. According to this document, the enlarged projection image is obtained by rotating the sample side and changing the distance between the X-ray generator and the sample. In this apparatus, the sample to be measured is an industrial product. It is also understood that the sample is measured in an exposed state.
[0004]
[Patent Document 1]
JP 2001-299786 A
[Patent Document 2]
JP-A-5-322802
[0005]
[Problems to be solved by the invention]
The configuration described in Patent Document 2 has an advantage that a large-scale mechanism for rotating the X-ray generation unit and the X-ray detection unit is unnecessary, and the magnification can be varied.
[0006]
However, the subject is directly held on the rotary table, and the subject is measured in a bare state as described above, and in the configuration, the measurement target is limited to a hard object whose shape does not change. Therefore, CT measurement of a flexible object such as a small animal cannot be performed using the configuration as it is. When measuring such a subject, it is desirable to maintain its position and orientation even when the subject is rotated. It is also necessary to consider hygiene.
[0007]
An object of the present invention is to provide an X-ray CT apparatus capable of stably maintaining the position and orientation of a subject when the subject is rotated and also capable of varying the magnification.
[0008]
Another object of the present invention is to provide a highly practical X-ray CT apparatus particularly suitable for small animals.
[0009]
[Means for Solving the Problems]
(1) The present invention provides an X-ray beam having a divergent shape. Horizontally A measurement unit including an X-ray generation unit that generates the X-ray beam, and an X-ray detection unit that detects the X-ray beam; Can be rotated while standing Provided, As a small animal Crosses the container containing the subject and the X-ray beam Vertical A rotation mechanism that rotates the container around a rotation center axis, and at least one of the X-ray generation unit, the X-ray detection unit, and the rotation center axis is displaced in the X-ray beam direction, whereby an image magnification is obtained. And a displacement mechanism for changing.
[0010]
According to the above configuration, the subject is accommodated in the container, and the container is rotated by the rotation mechanism. Subject Is dynamic Products, particularly preferably small animals of mice. The X-ray beam is relatively rotated and scanned by the rotation of the container around the rotation center axis of the container, whereby CT measurement is performed. The displacement mechanism is one of a distance between the rotation center axis and the X-ray generation unit and a distance between the rotation center axis and the X-ray detection unit in the X-ray beam direction (the direction of the center axis of the X-ray beam). Or make both variable. Although it is desirable to make the rotation center axis coincide with the container center axis, they may be inconsistent. Thereby, the subject passage width of the X-ray beam changes due to the nature of the X-ray beam having a divergent shape, and the magnification when a CT image is configured can be changed. In this case, the spatial resolution also varies. Usually, the magnification is varied so that the entire cross section of the subject is covered, but the magnification may be varied so that a part of the cross section is enlarged and observed. In that case, it is desirable to position the container so that the center of the part coincides with the rotation center axis. The concept of the divergent shape includes a fan beam shape that spreads two-dimensionally.
[0011]
Preferably, the displacement mechanism displaces the rotation center axis. If the rotation center axis of the container is displaced, the mechanism can be generally downsized compared to the case where the measurement unit is displaced. Preferably, the displacement mechanism displaces the container together with the rotation center axis.
[0013]
Preferably, the container is rotatably disposed in an upright state with the container center axis and the rotation center axis being aligned, and the rotation mechanism rotates the container in the upright state. A configuration in which the container is arranged in a horizontal state can also be adopted, but the subject needs to be restrained more firmly in order to prevent posture change due to gravity. If the container is arranged in a vertical state, the posture of the subject is hardly changed even if the container is rotated.
[0014]
Preferably, the container has a hollow cylindrical shape, and a fixing member for preventing the movement of the subject is disposed in the container. If the container has a hollow cylindrical shape, it is easy to accommodate small animals and the effective field capable of CT measurement on the X-ray beam scanning plane is circular, so that the cylindrical shape (circular cross section) is reasonable. .
[0015]
Desirably, the front-end | tip part of the said container has the cone shape which protruded, and the said rotation mechanism has a rotation plate provided with the hollow which the said front-end | tip part engages. The distal end portion of the container and the rotating plate are engaged, whereby the container is positioned on the distal end side (lower end side or upper end side in the standing state).
[0016]
Preferably, the rotation mechanism includes a rotation holder that rotates while holding the base end portion of the container. If the base end of the container is held, transmission of X-rays to the main part of the container in which the subject is accommodated is not hindered.
[0017]
Preferably, a plurality of types of containers having different sizes are selectively used as the container. According to this configuration, an appropriate container can be selectively used according to the size of the subject. Desirably, the distal end portions of the plurality of types of containers each have a protruding conical shape, and the proximal end portions of the plurality of containers have the same outer diameter.
[0018]
(2) Further, according to the present invention, in an X-ray CT apparatus for small animals, an X-ray generator that generates an X-ray beam having a fan beam shape in a horizontal direction, and an X-ray detector that detects the X-ray beam A measurement unit comprising: a container that is provided in a standing state at a position where the X-ray beam is transmitted, and that accommodates the small animal in a standing state; a moving mechanism that moves the container in a vertical direction; and the X-ray A rotation mechanism that rotates the container around a vertical rotation center axis that intersects the beam, and at least one of the X-ray generation unit, the X-ray detection unit, and the rotation center axis is displaced in the X-ray beam direction. And a displacement mechanism for changing the magnification of the image.
[0019]
Preferably, the displacement mechanism displaces the container together with the moving mechanism and the rotating mechanism.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 shows an example of an X-ray CT apparatus. This X-ray CT apparatus is an apparatus for performing CT measurement particularly on mice such as mice, rats, mice, guinea pigs and hamsters. This X-ray CT apparatus is roughly divided into a measurement unit 10 and a calculation control unit 12.
[0022]
The measurement unit 10 has a main body 16 having a gantry 18. An opening is formed in the upper surface 16A of the main body 16, and an arm 26 projects upward from the opening. The arm 26 forms a part of a slide mechanism described later. The arm 26 is connected to a container 24 described later, and slides in the direction of the central axis.
[0023]
On the other hand, measurement units (X-ray generator, X-ray detector), which will be described later, are accommodated in the gantry 18 and rotate around the rotation center axis. A hollow portion 18A is formed in the central portion of the gantry 18 in the direction of the rotation center axis.
[0024]
The container 24 is a capsule that houses a small animal as a subject, and the container 24 has a substantially cylindrical shape in the present embodiment, and is arranged in a state in which the container center axis coincides with the rotation center axis. Specifically, the base end portion 76 of the container 24 is detachably attached to the upper end portion of the arm 26 described above. In this case, examples of the attachment / detachment mechanism include various engagement mechanisms or screwing mechanisms. As described above, the container 24 has a hollow cylindrical shape, and a small animal is disposed therein. With such a configuration, the body hair of the small animal directly contacts the gantry 18. Can be prevented. In addition, it is possible to prevent the problem that small animal excrement or detached hair is released to the outside. Furthermore, since it becomes possible to restrain a small animal as will be described later, problems such as image blurring when a CT image is reconstructed can be prevented. It is desirable to prepare and selectively use a plurality of types of containers having different sizes and shapes.
[0025]
After the container 24 is attached to the arm 26, the arm 26 is driven forward along the direction of the rotation center axis, whereby the container 24 is inserted into the cavity 18A of the gantry 18. At this time, the container 24 is positioned so that the X-ray beam is set with respect to the cross section at a predetermined position in the subject. Further, such a measurement position is changed continuously or stepwise as necessary.
[0026]
An operation panel 20 is provided on the upper surface 16A of the main body 16, and the operation panel 20 includes a plurality of switches, indicators, and the like. Using this operation panel 20, the user can operate the operation of the apparatus at the measurement site. A plurality of casters 22 are provided below the main body 16. Incidentally, the height of the measurement unit 10 is, for example, 100 cm.
[0027]
Next, the arithmetic control unit 12 will be described. The arithmetic control unit 12 is electrically connected to the measurement unit 10 by a cable 14. The measurement unit 10 and the calculation control unit 12 may be provided in the same room, or may be installed in different places. The arithmetic control unit 12 is configured by a normal computer system or the like, and specifically includes a processor 30, a display 32, a keyboard 36, a mouse 38, a storage device 34, a printer 40, and the like. The operation control unit 12 controls the operation of the measurement unit 10, and a CT image is configured based on data transmitted from the measurement unit 10. This CT image usually corresponds to a two-dimensional tomographic image, but a three-dimensional image may be constructed. Incidentally, in the apparatus of the present embodiment, the rotation speed of the measurement unit in the gantry 18 is, for example, 10 rotations per minute. Of course, such a rotation speed can be appropriately set according to the application.
[0028]
FIG. 2 is a block diagram showing the components of the X-ray CT apparatus shown in FIG. An X-ray generator 52 is provided on one side and an X-ray detector 60 is provided on the other side with the rotation center axis O therebetween. A collimator 54 is provided on the irradiation side of the X-ray generator 52. The X-ray generator 52 generates a divergent or fan-shaped (here, fan-beam shaped) X-ray beam 56 as shown. On the other hand, the X-ray detector 60 is configured as a plurality of (for example, 100) X-ray sensors arranged in a line, and an X-ray receiving opening is set according to the opening angle of the X-ray beam 56. Incidentally, the arrangement of the plurality of X-ray sensors may be linear or arcuate.
[0029]
In FIG. 2, the high voltage source used with the X-ray generator 52, the data processing circuit used with the X-ray detector 60, and the like are not shown.
[0030]
In FIG. 2, reference numeral 58 denotes an effective field of view. This is a circular region in which a CT image can be formed when the X-ray beam 56 is rotationally scanned. Incidentally, the effective visual field 58 is determined according to the positional relationship between the subject or the rotation center axis and the X-ray generator 52 and the X-ray detector 60. In this embodiment, since a displacement mechanism 62 described below is provided, it is possible to mechanically vary the magnification of the CT image by changing their positional relationship.
[0031]
That is, the X-ray generator 52 and the X-ray detector 60 are connected to the displacement mechanism 62, and the displacement mechanism 62 maintains the distance between the X-ray generator 52 and the X-ray detector 60. (That is, the measurement unit) has a function of displacing in the beam axis direction of the X-ray beam 56. In this case, the rotation center axis O is not changed, that is, the magnification can be changed by moving the measurement unit without moving the container described above. This will be described in detail later with reference to FIGS. The displacement mechanism 62 includes a motor 62A for generating a displacement force.
[0032]
The gantry rotating mechanism 66 is a mechanism that rotates the entire structure including a displacement mechanism mounted thereon by rotating a rotating base described later. Since the measurement unit is mounted on the displacement mechanism 62, the measurement unit positioned at a desired position by the displacement mechanism 62 is rotationally driven while maintaining the position. The gantry rotating mechanism 66 has a motor 66A for generating the driving force.
[0033]
The slide mechanism 68 is a moving mechanism that slides the arm 26 shown in FIG. 1, and the driving force is generated by the motor 68A. The operation panel 20 is provided on the upper surface of the main body as described above. The operation panel 20 may be connected to a local controller (not shown) provided on the measurement unit 10 side so that the local controller and the arithmetic control unit 12 communicate with each other.
[0034]
Incidentally, although various mechanisms 62, 66, 68 and the like are shown in FIG. 2, it is desirable to provide a sensor in order to detect a position or a change due to these mechanisms. Then, it is desirable that the arithmetic control unit 12 performs so-called feedback control based on the output signals of those sensors. The magnification change by the displacement mechanism 62 may be performed by user input. For example, the subject size or the container size is automatically detected, and the magnification is automatically set based on the detected data. Also good. Furthermore, when the container type or the like is registered in advance, the magnification may be set using the registered information. Further, in the example shown in FIG. 2, the slide mechanism 68 has the motor 68A as a drive source, but the slide force may be generated artificially.
[0035]
Next, the arithmetic control unit 12 will be described. As described above, the display unit 32, the storage device 34, the keyboard 36, the mouse 38, the printer 40, and the like are connected to the processor 30. In addition, a communication unit 42 for communicating with an external device via a network is connected.
[0036]
The processor 30 is configured by a CPU, an operation control program, an image processing program, and the like. FIG. 2 shows typical functions thereof, and the processor 30 includes an operation control unit 44 and a reconstruction calculation unit 46. The operation control unit 44 controls the overall operation of the measurement unit 10. The reconstruction calculation unit 46 executes a calculation for forming a CT image based on a lot of data obtained by rotational scanning of the X-ray beam. In this case, a three-dimensional image may be constructed. Various known methods can be used for the reconstruction operation. Note that, in changing the magnification described above, the arithmetic expression used in the reconstruction calculation can be basically used as it is. However, when a special variable magnification method is applied, a part of the reconstruction calculation expression may be changed as necessary.
[0037]
On the display 32, the CT image is displayed as a tomographic image or the like. In this case, it is desirable to display a numerical value or a scale representing a magnification (enlargement ratio). According to this configuration, the size of the object can be evaluated when the image is visually determined. That is, for example, the amount of fat and the size of a tumor can be determined quantitatively.
[0038]
FIG. 3 shows a cross section of the container 24 shown in FIG. The container 24 is roughly composed of a container body 70 and a lid 72. A distal end portion 74 is provided on the distal end side of the container body 70, and the distal end portion 74 has a conical shape protruding forward. A through hole 78 is formed at the center of the tip 74.
[0039]
A proximal end portion 76 is provided on the proximal end side of the container body 70. As described above, the base end portion 76 is a portion to be mounted on the slide mechanism, but the mounting mechanism is not illustrated. The inside 70 </ b> B of the container main body 70 is partitioned by a distal end portion 74 on the distal end side, and is partitioned by a partition wall 80 on the proximal end side. A through hole 82 is formed in the central portion of the partition wall 80.
[0040]
The through holes 78 and 82 are holes into which, for example, tubes for introducing anesthetic gas are inserted. Of course, those through holes 78 and 82 may function as air holes. Even when the through holes 78 and 82 are formed, when the container 24 is arranged in a horizontal state, the filth and the like excreted from the small animal are stored in the interior 70B of the container body 70, and the external Can be prevented. Further, since the through-holes 78 and 82 are small holes, the detached hair is hardly released to the outside.
[0041]
An opening 70A is formed in the container body 70, and the lid 72 described above is provided in the opening 70A. The lid 72 may be opened and closed by, for example, a hinge, or may simply be attached to the container body 70 on one side with an adhesive tape or the like, or completely with respect to the container body 70. A configuration in which the lid 72 is separated may be used. In any case, it is desirable that the lid 72 is closed after the small animal is stored in the container body 70.
[0042]
Incidentally, the container 24 is formed of a transparent X-ray transmitting member as a whole. Examples of the material include resins such as acrylic and ABS.
[0043]
In the example shown in FIG. 3, the container 24 has a hollow, generally cylindrical shape as a whole, but other shapes may be adopted. For example, a rotationally symmetric shape around the central axis can be mentioned, and further, the cross section can be elliptical, D-shaped, or rectangular. Considering that the effective field of view 58 shown in FIG. 2 is circular, the cross section of the container 24 is preferably circular, and in that sense, it is desirable to adopt a cylindrical shape or a rotationally symmetric shape.
[0044]
Incidentally, in the example shown in FIG. 1, the container 24 is set in a horizontal state. However, in the example described later with reference to FIG. 24, the container 24 is set in an upright state. In this case, if the lower side of the container 24 is the tip portion 74, it is better not to form a through hole in the tip portion 74. The reason is that filths excreted from small animals are prevented from flowing out.
[0045]
In the example shown in FIG. 3, the length of the container 24 is 400 mm, for example, and the diameter (outer diameter) is 120 mm, for example. For example, one small animal or two small animals are accommodated in the interior 70B of the container body 70. Even in such a case, the tail of the small animal is not pulled out and can be stored in the container 24. In exceptional cases, the partition wall 80 may be formed with a hole for leading such a tail to the outside.
[0046]
Next, the usage example of the container 24 is demonstrated using FIGS.
[0047]
As shown in FIG. 4, a small animal 84 is accommodated in the inside 70 </ b> B of the container 24. In that case, as shown in FIG. 5, the lid 72 is opened with respect to the container body 70, and the small animal 84 is stored. Then, as shown in FIG. 6, the small animal 84 is held in the container 24 by closing the lid 72. In this case, even if hair, wrinkles, etc. exist, they are securely held in the container 24. That is, for example, it is possible to prevent a problem that the subject protrudes from the effective visual field 58 shown in FIG. In the example shown in FIGS. 4 to 5 described above, the small animal 84 is simply accommodated in the container 24. In such a case, CT measurement can be performed, but the small animal 84 is surely restrained. For this purpose, a fixing member as described below may be used.
[0048]
In FIG. 7, sponge bodies 86 and 88 that are elastically deformed are provided in the container 24A. That is, as shown in FIG. 8, a sponge body 86 is provided on the container body 70 side, and a sponge body 88 is provided on the lid 72 side. Then, as shown in FIG. 9, when the lid 72 is closed with respect to the container body 70, the entire periphery of the small animal 84 is wrapped by the sponge bodies 86 and 88, and the movement of the small animal 84 is suppressed and the small animal 84 is suppressed. Thus, it is possible to reliably prevent problems such as the occurrence of positional deviation.
[0049]
In this case, as the fixing member, for example, air packing may be used, or an adhesive fixing member may be provided. Furthermore, simply, the movement may be fixed by wrapping the small animal 84 with a clogging member such as gauze.
[0050]
According to the above configuration, the movement of the subject 80 can be prevented, and the surface of the small animal 84 can be separated from the inner surface of the container. That is, when the container material has an X-ray absorption coefficient equivalent to the fat or muscle of the small animal 84, if the small animal 84 is in contact with the inner surface of the container, the container itself is a part of the small animal. As such, there is a risk of being mistaken for data calculation. On the other hand, by inserting a material having a different X-ray absorption coefficient between the small animal 84 and the container, it is possible to discriminate both on the image and prevent the above-described misidentification.
[0051]
7 to 9, the fixing member is divided into two parts on the container body 70 side and the lid 72 side. However, various methods other than the above can be adopted as the fixing member arrangement method.
[0052]
10 to 12 show other examples. As shown in FIG. 10, a plurality of through holes 90 are formed in each of the container main body 70 and the lid 72 in the container 24B, and a linear member 92 such as a string having an elastic action is formed in each of the through holes 90. It is being handed over. For example, the linear member 92 is rubber or the like.
[0053]
As shown in FIG. 11, in a state where the lid 72 is opened, the small animal 84 is placed on the plurality of linear members 92 that are stretched in parallel with each other, and then the lid 72 is closed. As described above, the small animal 84 is sandwiched between the plurality of linear members 96 provided on the lid 72 side and the above-described plurality of linear members 92, thereby achieving pressing and fixing.
[0054]
The example shown in FIGS. 11 to 12 is an example, and other than this, for example, a pair of sheet-like members having elastic force may be provided so that the small animal 84 is sandwiched from both sides thereof. 10 to 12, the body surface of the small animal 84 can be separated from the inner surface of the container.
[0055]
Therefore, if CT measurement is performed on a small animal using the container described above, the small animal can be confined in a certain circular area on the CT scanning plane, and a part of the small animal may contact the device, Alternatively, it is possible to prevent the filth from being released from the small animal from being released or causing sanitary problems. Furthermore, since the movement of the small animal can be suppressed by the fixing member, problems caused by the movement of the object during measurement can be prevented, and the body surface of the small animal can be separated from the inner surface of the container. In this case, there is an advantage that image processing can be easily performed. Furthermore, in the above-described example, since the container is made of a transparent member, it is possible to observe the appearance of a small animal from the outside even during CT measurement. In the present embodiment, the entire container is made of a transparent member. However, it is sufficient that a part of the container is transparent as long as observation can be performed.
[0056]
Next, variable magnification by the displacement mechanism described above will be described with reference to the schematic diagrams of FIGS.
[0057]
In FIG. 13, reference numeral 100 denotes a rotation center axis. In the X-ray CT apparatus, the X-ray generator 52 and the X-ray detector 60 perform rotational movement with the rotation center axis 100 as the rotation center. In this case, the effective visual field 102 is defined by an inscribed circle when the X-ray beam 101 is rotationally scanned. This effective visual field 102 corresponds to the photographing range. The X-ray beam 101 has a divergent shape, that is, a fan beam.
[0058]
FIG. 14 shows the positional relationship between the components. Here, the distance from the rotation center axis 100 to the X-ray generator 52 is defined as R, and the distance from the X-ray generator 52 to the X-ray detector 60 is defined as L. Incidentally, the distance from the rotation center axis 100 to the X-ray detector 60 is represented by T. Assuming the X-ray beam 101 having the above fan beam shape, the magnification of the image is determined by L / R, and the magnification, that is, the enlargement ratio increases as the fractional value increases. What can be said from this is that the magnification can be varied by moving at least one of the X-ray generator 52, the rotation center axis, and the X-ray detector 60.
[0059]
In FIG. 15, a relatively large object (subject) 104 exists in the effective visual field 102. When the object 104 is imaged in the geometrical relationship as shown in FIG. 15, it becomes as shown by reference numeral 104A. That is, the object is displayed in a considerably large size on the screen. In this example, the center of the object 104 coincides with the rotation center axis, whereby the center of the image coincides with the center of the object 104A.
[0060]
On the other hand, as shown in FIG. 16, when there is a relatively small object 106 with respect to the effective visual field 102, the size of the object on the screen becomes very small as indicated by reference numeral 106A. As a result, there arises a problem that the diagnosis of the object cannot be accurately performed. Therefore, as shown in FIG. 17, for example, by reducing R while keeping L constant (in other words, by increasing T), even a small object 106 is displayed on the screen as indicated by reference numeral 106B. It becomes possible to express it greatly. That is, it is possible to realize zoom up. In this example, similarly to the above, the center of the object 106 coincides with the rotation center axis, and thus the center of the image and the center of the object 106A also coincide.
[0061]
Of course, in the case shown in FIG. 16, it is possible to enlarge the obtained data by image processing, but this cannot improve the spatial resolution itself. However, according to the technique as shown in FIG. 17, the spatial resolution itself can be increased, so that there is an advantage that a highly accurate enlarged image can be obtained.
[0062]
Here, considering the variable magnification method, at least one of the X-ray generator 52, the rotation center axis (in this example, coincides with the center of the object 106), and the X-ray detector 60 is arranged in the X-ray beam axis direction. It is understood that it is only necessary to move. Incidentally, when the distance L between the X-ray generator 52 and the X-ray detector 60 is varied, it is desirable to set a certain opening for the X-ray detector 60.
[0063]
The principle described above will be further described with reference to FIGS. 18 and 19. In the case shown in FIG. 18, the distance between the X-ray generator 52 and the object 108 is R1, and in that case, the X-ray beam Only a portion indicated by reference numeral 110 in 101 passes through the object 108. In this case, the X-ray intensity observed in the X-ray detector 60 is as illustrated. In other words, only the central sensor among many X-ray sensors (elements) acquires valid data.
[0064]
On the other hand, as shown in FIG. 19, when the object 108 is brought close to the X-ray generator 52 and the distance between the two is R2 (R1> R2), the range (reference numeral) of the X-ray beam 101 that passes through the object 108. 112) is enlarged, and a large part of the X-ray sensor in the X-ray detector 60 acquires valid data. It is understood from this that the spatial resolution is improved. Of course, even when the distance between the X-ray generator 52 and the X-ray detector 60 is not constant, the advantage of improving the spatial resolution can be obtained.
[0065]
Incidentally, when acquiring a CT image of a small animal, the CT image may be formed so as to cover the entire abdomen of the small animal, or an enlarged image of some organs in the abdomen may be acquired. You may make it set a magnification. That is, instead of aligning the rotation center axis with the center of the object, for example, the rotation center axis may be aligned with the center of the portion to be enlarged. Therefore, a mechanism for moving the object not only in the direction of the X-ray beam but also in a direction orthogonal to both the X-ray beam and the rotation center axis may be provided.
[0066]
The principle described above is not limited to the X-ray CT apparatus, and can be applied to, for example, a bone mineral content measuring apparatus and an X-ray imaging apparatus using X-rays.
[0067]
Next, a specific configuration and operation of the measurement unit 10 illustrated in FIG. 1 will be described with reference to FIGS. First, the configuration of the measurement unit 10 will be described with reference to FIG. As described above, the X-ray generator 52 is provided on one side with respect to the rotation center axis, and the X-ray detector 60 is provided on the other side. Reference numeral 101 denotes a fan beam-shaped X-ray beam, and reference numeral 102 denotes the above-described effective visual field. Reference numeral 120 represents the shape of the cavity in the gantry.
[0068]
A belt 122 is wound around the motor 66A, and the rotational force of the belt 122 is transmitted by the rotational movement of the movable portion 50 by driving the belt 122 to rotate. The movable part 50 is constituted by various mechanisms mounted on the rotary base 123. Specifically, a displacement mechanism 62 is provided on the rotation base 123, and the displacement mechanism 62 is shown as a first mechanism 62L and a second mechanism 62R in FIG. Each of the first mechanism 62L and the second mechanism 62R has a member 134 fixed on the rotation base 123, and a guide 132 for slidably receiving the rail 130 fixed to the frame 124 is provided on the member 134. ing. Incidentally, the first mechanism 62L is not shown for the rail 130 and the guide 132.
[0069]
The rails 130 are provided on both sides of the frame 124, that is, the frame 124 is slidably held on both sides thereof. An X-ray generator 52 and an X-ray detector 60 are mounted on the frame 124.
[0070]
The first mechanism 62L has a motor 62A, and the rotational force thereof is transmitted to the feed screw 126. A bearing 128 is engaged with the feed screw 126. The bearing 128 is fixed to the rotating base 123. Therefore, when the feed screw 126 is rotated, the frame 124 moves forward or backward depending on the engagement relationship between the feed screw 126 and the bearing 128. That is, the measurement unit including the X-ray generator 52 and the X-ray detector 60 can be displaced with respect to the rotation center axis.
[0071]
FIG. 21 shows a state where the movable part 50 is rotated from the state shown in FIG.
[0072]
On the other hand, FIG. 22 shows a state in which the feed screw 126 is rotated as described above and the frame 124 is pulled upward from the engagement relationship between the lead screw 126 and the bearing 128. Since the X-ray beam 101 has a divergent shape, the effective visual field 102 is extremely small in the state of FIG. That is, this means that the magnification has been increased. FIG. 23 shows a state where the movable unit 50 is rotated from the state shown in FIG. During the rotation, the displacement state of the measurement unit once set is maintained.
[0073]
In the above embodiment, the driving force for changing the magnification is generated by the motor 62A. However, it may be generated by an artificial force. Even in such a case, a mechanism for sliding the measurement unit in the beam axis direction of the X-ray beam and maintaining the displacement state once set is necessary.
[0074]
FIG. 24 shows another example of the X-ray CT apparatus. In the example shown in FIG. 1, the container moves only in the direction of the rotation center axis. However, in the example shown in FIG. 24, the container itself is driven to rotate and its position is changed to change the magnification.
[0075]
In FIG. 24, an X-ray generator 204 and an X-ray detector 206 are fixedly arranged on the base 202. A container 208 is set between them as described below. The container 208 has, for example, the same form as the container 24 shown in FIG. 3 except that the through-hole 78 shown in FIG. 3 does not exist because the container 202 is set upright. In other words, this is to prevent filth from flowing out from the inside of the container 208. Except for the absence of the through hole 78, the specific configuration of the container 208 is the same as the example shown in FIGS.
[0076]
On the base 202, the plates 212, 214, and 216 are arranged in an upright state. The displacement mechanism 210 is held by these plates 212, 214, and 216. The displacement mechanism 210 will be described in detail below.
[0077]
Between the plate 214 and the plate 216, two poles 218 and 220 are arranged in parallel with each other at a predetermined interval in the vertical direction. The slider 222 is provided so as to be slidable in the X direction in the figure relative to the poles 218 and 220. A pulley 226 is connected to the X motor 230, and a wire 228 is stretched between the pulley 226 and the other pulley 224. The slider 222 is coupled to the middle of the wire 228. That is, when the X motor 230 is driven, the wire 228 rotates, and as a result, the slider 222 slides in the X direction according to the rotation of the wire 228. By this sliding motion, the entire movable part 300 including the displacement mechanism 210 moves in the X direction, and the magnification can be varied as will be described later. That is, as shown in FIG. 14, R can be varied with L being constant.
[0078]
The slider 222 is provided with a Z motor 232, and the screw 234 is rotationally driven by the Z motor 232. A bearing 236 is engaged with the screw 234, and the bearing 236 is fixed to the vertical plate 238. Therefore, when the Z motor 232 is driven to rotate, the screw 234 rotates and the bearing 236 engaged therewith moves in the Z direction in the drawing. As a result, the vertical plate 238 also moves.
[0079]
The vertical plate 238 is provided with a horizontal plate 240 on the lower side and a horizontal plate 241 on the upper side thereof. A circular rotating plate 244 is provided on the upper surface of the horizontal plate 240. The rotating plate 244 has a depressed center, that is, has a funnel-like shape, and itself can freely rotate.
[0080]
On the other hand, the horizontal plate 241 is provided with a ring-shaped rotation holder 242. The rotating holder 242 has a structure for holding the proximal end portion of the container 208. A motor 246 is provided at the upper end of the vertical plate 238, and a roller 248 is connected to the shaft of the motor 246. The roller 248 is in contact with the outer peripheral surface 242A of the rotation holder 242. Therefore, when the motor 246 is driven, the rotation holder 242 is rotationally driven by the contact relationship between the roller 248 and the outer surface 242A. That is, the container 208 rotates.
[0081]
In this case, the distal end portion or the lower end portion of the container 208 has a conical shape as described above, which matches the funnel-shaped shape of the rotating plate 244. That is, the rotational movement of the container 208 is performed without causing the central axis to move from side to side. Therefore, when the container 208 is rotated in a state where the slider 222 is set at a certain position in the X direction, a CT image of the subject stored in the container 208 is formed at a magnification corresponding to the position of the slider 222. The rotation speed is, for example, 0.2 rotations per second.
[0082]
The image thus formed is displayed on a display provided in an arithmetic control unit (see FIGS. 1 and 2) not shown.
[0083]
On the other hand, when it is desired to change the magnification, the slider 222 is moved in the X direction to set a desired magnification. As described above, X-ray CT images can be obtained by continuously irradiating the X-ray beam 201 while rotating the container 208 at a constant speed.
[0084]
In the above embodiment, the container 208 is arranged in an upright state, and the container 208 itself is rotationally driven, which is different from the configuration shown in FIG. However, a CT image can be obtained by any method, and it is desirable to select any method according to the contents of the subject or the purpose of measurement.
[0085]
In the example shown in FIG. 24, there is an advantage that a large-scale mechanism is not required to rotate the container 208 itself. As shown in FIG. 24, when the container 208 is raised and rotated, the container 208 is placed in a horizontal state and rotated in combination with the action of the fixing member in the container described above. Compared to, the subject is less likely to be displaced.
[0086]
Incidentally, when obtaining a tomographic image of a certain part of the subject and forming a tomographic image of the next part, the container 208 is moved in the Z direction by the Z motor 232 as described above. In this case, such a vertical movement may be performed using an artificial force, and this also applies to a movement in the X direction.
[0087]
FIG. 25 shows two types of containers 208 and 250. The container 208 shown in (B) is the same as the container shown in FIG. 24, and is the same as that shown in FIG. 3 except that the through-hole 78 provided at the tip is not formed.
[0088]
On the other hand, the container 250 shown in (A) has a smaller main portion diameter than the container 208 shown in (B), while the outer shape of the base end portion 250A matches the outer shape of the base end portion 208A of the container 208. ing. Further, the tip 250B of the container 250 has a conical shape as described above. According to the configuration shown in FIG. 25, since the tip portion of each container has a conical shape, any type of container can be engaged with the rotating plate 244. Even in the type of container, since the outer diameters of the base end portions thereof coincide, the container can be reliably held by the rotary holder 242.
[0089]
FIG. 26 shows a state in which the container 250 shown in FIG. 25A is set. When 250 having such a small size is used, the container 250 is moved by the displacement mechanism 210, for example. X-ray measurement is performed in a state where the X-ray generator 204 is positioned closer to the X-ray generator 204, that is, in a state where the magnification is increased.
[0090]
The container shown in FIG. 25 is an example, and containers having other shapes can be used. In any case, the above-described various advantages can be obtained by performing measurement in a state where the object is stored, that is, the object is wrapped.
[0091]
Incidentally, the container described above is not limited to the X-ray CT apparatus, and can be used in, for example, a bone mineral content measuring apparatus and an X-ray imaging apparatus using X-rays, and the same advantages as described above can be obtained.
[0092]
【The invention's effect】
According to the present invention, when the subject is rotated, the position and posture of the subject can be stably held, and the magnification can be varied.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an overall configuration of an X-ray CT apparatus related to the present invention.
FIG. 2 is a block diagram showing the overall configuration of the X-ray CT apparatus shown in FIG.
FIG. 3 is a cross-sectional view of a container that accommodates a subject.
FIG. 4 is a perspective view showing an example of use of the container.
FIG. 5 is a cross-sectional view showing an example of use of the container.
FIG. 6 is a cross-sectional view showing an example of use of the container.
FIG. 7 is a perspective view showing an example of use of the container.
FIG. 8 is a cross-sectional view showing an example of use of the container.
FIG. 9 is a cross-sectional view showing an example of use of the container.
FIG. 10 is a perspective view showing an example of use of the container.
FIG. 11 is a cross-sectional view showing an example of use of a container.
FIG. 12 is a cross-sectional view showing an example of use of the container.
FIG. 13 is a diagram for explaining an effective visual field.
FIG. 14 is a diagram for explaining the positional relationship of each member.
FIG. 15 is a diagram illustrating a relationship between an effective visual field and a relatively large object.
FIG. 16 is a diagram showing a relationship between an effective visual field and a relatively small object.
FIG. 17 is a diagram for explaining formation of an enlarged image of an object.
FIG. 18 is a diagram for explaining X-rays that pass through an object;
FIG. 19 is a diagram for explaining X-rays that pass through an object;
FIG. 20 is a diagram illustrating the operation of the measurement unit when the magnification is small.
FIG. 21 is a diagram illustrating the operation of the measurement unit when the magnification is small.
FIG. 22 is a diagram illustrating the operation of the measurement unit when the magnification is large.
FIG. 23 is a diagram illustrating the operation of the measurement unit when the magnification is large.
FIG. 24 is a perspective view showing a main configuration of an X-ray CT apparatus related to the present invention.
FIG. 25 is a view showing various containers.
FIG. 26 is a diagram showing an example in which a small-sized container is used in the X-ray CT apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Measurement part, 12 Calculation control part, 16 Main body, 18 Gantry, 20 Operation panel, 24 Container, 30 Processor, 44 Operation control part, 46 Reconfiguration calculation part, 50 Movable part, 52 X-ray generator, 60 X-ray detection 62, displacement mechanism, 66 gantry rotation mechanism, 68 slide mechanism, 200 measuring section, 204 X-ray generator, 206 X-ray detector, 208 container, 210 displacement mechanism, 300 movable section.

Claims (10)

A measurement unit comprising: an X-ray generator that generates an X-ray beam having a divergent shape in the horizontal direction; and an X-ray detector that detects the X-ray beam;
A container which is rotatably provided in a standing state at a position where the X-ray beam is transmitted, and which contains a subject as a small animal ;
A rotation mechanism for rotating the container about a rotation center axis in a vertical direction intersecting the X-ray beam;
A displacement mechanism that displaces at least one of the X-ray generation unit, the X-ray detection unit, and the rotation center axis in the X-ray beam direction, thereby changing the magnification of the image;
X-ray CT apparatus characterized by including. The apparatus of claim 1.
The X-ray CT apparatus, wherein the displacement mechanism displaces the rotation center axis. The apparatus of claim 2.
The X-ray CT apparatus characterized in that the displacement mechanism displaces the container together with the rotation center axis. The apparatus of claim 1.
An X-ray CT apparatus comprising a moving mechanism for moving the container in a vertical direction . The apparatus of claim 1.
The container is disposed so as to be rotatable in an upright state while matching the container center axis and the rotation center axis.
The X-ray CT apparatus, wherein the rotation mechanism rotates the container in the upright state around the container central axis . The apparatus of claim 5.
The X-ray CT apparatus, wherein the container has a hollow and substantially cylindrical shape, and a fixing member for preventing the movement of the subject is disposed therein. The apparatus of claim 1.
The tip of the container has a protruding conical shape,
The X-ray CT apparatus, wherein the rotation mechanism includes a rotation plate having a recess with which the tip end portion is engaged. The apparatus of claim 1.
The X-ray CT apparatus, wherein the rotation mechanism includes a rotation holder that rotates while holding a base end portion of the container. The apparatus of claim 1.
An X-ray CT apparatus, wherein a plurality of types of containers having different sizes are selectively used as the container. The apparatus of claim 9.
The X-ray CT apparatus characterized in that the distal end portions of the plurality of types of containers each have a protruding conical shape, and the base end portions of the plurality of containers have the same outer diameter.

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