X-ray computed tomography equipment and gantry

Abstract

To reduce noise while maintaining a cooling function for various kinds of units mounted on a rotary frame.SOLUTION: An X-ray computer tomography apparatus includes a rotary frame and a support frame. An X-ray tube for generating an X-ray is attached to the rotary frame. The support frame rotatably supports the rotary frame along a predetermined rotation direction around a rotation axis. The rotation frame includes at least one opening in a surface along the rotation axis. At least one of a first edge on a rotation direction side of the opening and a second edge on a side opposite to the rotation direction side of the opening is non-parallel to the rotation axis.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings relate to an X-ray computed tomography apparatus and a gantry apparatus. [Background technology]

[0002] Conventionally, a gantry for an X-ray computed tomography apparatus has a rotating frame on which various units are mounted. The various units (e.g., X-ray tubes) can generate heat during operation of the X-ray computed tomography apparatus. To prevent the various units from breaking down due to heat, the various units must be cooled. For this reason, openings are provided on the side of the rotating frame parallel to the rotation axis of the rotating frame to serve as flow paths for air that has cooled the various units.

[0003] The air that has cooled the various units flows out (exhaust) from the openings on the rotating frame to the outside in the radial direction of the rotating frame (hereinafter referred to as the radial outward direction) as the rotating frame rotates. The airflow flowing out from the openings collides with the tip of the support frame that faces the rotating frame and supports the rotating frame. At this time, a noise (also called narrow-band noise or peak noise) that is harsh to the subject and / or user is generated at a frequency related to the rotation speed of the rotating frame and the airflow flowing out from the openings.

[0004] Completely closing the openings prevents air from flowing out of the openings, thereby suppressing the generation of noise. However, completely closing the openings blocks the cooling intake and exhaust flow paths to the various units mounted on the rotating frame. This prevents the various units from being adequately cooled, which could result in breakdowns of the various units. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-151616 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce noise while maintaining the cooling function for the various units mounted on the rotating frame. However, the problem to be solved by the embodiments disclosed in this specification and the drawings is not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0007] The X-ray computed tomography apparatus according to this embodiment includes a rotating frame and a support frame. An X-ray tube that generates X-rays is attached to the rotating frame. The support frame supports the rotating frame so that the rotating frame can rotate around a rotation axis along a predetermined rotation direction. The rotating frame has at least one opening on a surface along the rotation axis. At least one of a first edge of the opening on the rotation direction side and a second edge of the opening on the opposite side to the rotation direction is non-parallel to the rotation axis. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the arrangement of an X-ray CT apparatus according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing an example of the gantry device with an exterior cover removed according to the embodiment. [Figure 3] FIG. 3 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame and an example of a change in the relative value of acoustic power level depending on the angle of the corner of the opening in the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame and an example of a change in the relative value of the acoustic power level depending on the angle of the corner of the opening in the embodiment. [Figure 5]FIG. 5 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame and an example of a change in the relative value of acoustic power level depending on the angle of the corner of the opening in the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame according to an embodiment, and an example of a change in the relative value of acoustic power level according to the angle D between a first corner and a second corner of the opening. [Figure 7] FIG. 7 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame and an example of a change in the relative value of acoustic power level according to the angle between a first corner and a second corner of the opening in the embodiment. [Figure 8] FIG. 8 is a diagram showing an example of the shape of an opening provided on a side surface of a rotating frame and an example of a change in the relative value of acoustic power level according to the angle between a first corner and a second corner of the opening in the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of airflow (indicated by arrows) flowing out from a rectangular opening, according to a comparative example of the embodiment. [Figure 10] FIG. 10 is a schematic diagram illustrating a comparative example of the embodiment, showing how air currents A and B collide with the leading end of the frame as the rotating frame rotates. [Figure 11] 11 is a diagram showing an example of airflow A and airflow B at an opening corresponding to FIG. 6 according to the embodiment. [Figure 12] FIG. 12 is a diagram showing an example of changes in pressure at the tip of the frame in the embodiment and a comparative example. [Figure 13] 13 is a diagram showing an example of the shape of the opening and the tip corner at the tip of the frame shown in FIG. 6 according to a modified example of the embodiment, and an example of the change in the relative value of the acoustic power level depending on the angle of the tip corner at the tip of the frame. [Figure 14] 14 is a diagram showing an example of the shape of the opening and the tip corner at the tip of the frame shown in FIG. 5 according to a modified example of the embodiment, and an example of the change in the relative value of the acoustic power level depending on the angle of the tip corner at the tip of the frame. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT (computed tomography) apparatus) and a gantry will be described in detail with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0010] (Embodiment) FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus 1 according to this embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 includes, for example, a gantry apparatus 10, a bed apparatus 30, and a console apparatus 40. In this embodiment, the rotation axis of the rotating frame 13 in a non-tilted state or the longitudinal direction of the tabletop 33 of the bed apparatus 30 is defined as the Z-axis direction, the axial direction perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction, and the axial direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. For convenience of explanation, multiple gantry apparatuses 10 are depicted in FIG. 1, but the actual configuration of the X-ray CT apparatus 1 includes only one gantry apparatus 10.

[0011] The gantry 10 and the bed 30 operate based on a user's operation via the console 40 or an operation unit provided on the gantry 10 or the bed 30. The gantry 10, the bed 30, and the console 40 are connected to each other by wire or wirelessly so as to be able to communicate with each other.

[0012] FIG. 2 is a perspective view showing an example of a gantry 10 with its exterior cover removed. The gantry 10 is an apparatus having an imaging system that irradiates a subject P with X-rays and collects projection data from detection data of the X-rays that have passed through the subject P. As shown in FIGS. 1 and 2, the gantry 10 has a support frame, an X-ray tube 11 (X-ray generator), an X-ray detector 12, a rotating frame 13, an X-ray high-voltage device 17, a control device 18, a collimator 19, a wedge 20, and a DAS (Data Acquisition System) 21. The support frame supports the rotating frame 13 so that it can rotate around a rotation axis (Z-axis) in a predetermined rotation direction. The support frame has a fixed frame 5, a pair of standing frames 6, a base stand 7, and two gantry arms 8.

[0013] As shown in Figure 2, the fixed frame 5 supports the rotating frame 13 rotatably around the rotation axis R1 via bearings. The fixed frame 5 is a metal frame made of metal such as aluminum with a bore (opening) formed in the center. The fixed frame 5 supports the rotating frame 13 rotatably around the rotation axis R1 (Z-axis) via bearings (hereinafter referred to as support bearings). A pair of standing frames 6 are attached to both side surfaces of the fixed frame 5 via platform arms 8.

[0014] A base stand 7 is attached to the other end of the pair of standing frames 6. The pair of standing frames 6 are erected on the base stand 7. The base stand 7 is installed on the floor of the examination room SR. The base stand 7 supports the fixed frame 5 via the standing frames 6, spaced apart from the floor. The base stand 7 is made of metal such as aluminum.

[0015] Two gantry arms 8 support the fixed frame 5 so that they can tilt around a horizontal axis (X-axis) R2 that is perpendicular to the rotation axis R1 and parallel to the floor. Each gantry arm 8 is attached to the top of the base stand 7, connecting the base stand 7 to the fixed frame 5. When the fixed frame 5 is tilted, a vertical axis R3 that is perpendicular to the rotation axis R1 and the horizontal axis R2 tilts relative to the floor. The gantry arms 8 tilt the fixed frame 5 in response to a drive signal supplied from a drive unit (not shown). The gantry arms 8 are made of metal such as aluminum. The side of the rotating frame 13 on which the X-ray tube 11 and other components are attached is referred to as the front side, and the side facing the fixed frame 5 is referred to as the back side. The tip 15 of each gantry arm 8, in other words, the tip of the support frame facing the rotating frame 13 (hereinafter referred to as the frame tip) 15, is close to the rotating frame 13 without contacting it.

[0016] The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermoelectrons from a cathode (filament) toward an anode (target) when a high voltage is applied from the X-ray high voltage device 17 and a filament current is supplied. X-rays are generated when the thermoelectrons collide with the target. The X-rays generated at the tube focus of the X-ray tube 11 are shaped into a cone beam via, for example, a collimator 19 and irradiated onto the subject P. For example, the X-ray tube 11 may be a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons. Note that this embodiment can be applied to both a single-tube X-ray CT device and a so-called multi-tube X-ray CT device in which multiple pairs of X-ray tubes 11 and X-ray detectors 12 are mounted on a rotating frame 13.

[0017] The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and passing through the subject P, and outputs an electrical signal corresponding to the X-ray dose to the DAS 21. The X-ray detector 12 has, for example, multiple detection element rows in which multiple detection elements are arranged in the channel direction along an arc centered on the focal point of the X-ray tube 11. The X-ray detector 12 has, for example, a structure in which multiple detection element rows are arranged in the slice direction (column direction, row direction).

[0018] The X-ray CT apparatus 1 is available in a rotate / rotate type (third generation CT) in which the X-ray tube 11 and the X-ray detector 12 rotate together around the subject P, and a stationary / rotate type (fourth generation CT) in which a large number of X-ray detection elements arranged in a ring shape are fixed and only the X-ray tube 11 rotates around the subject P, and either type can be applied to this embodiment. For the sake of specificity, the X-ray CT apparatus 1 of this embodiment will be described below using a third generation CT as an example.

[0019] The X-ray detector 12 is an indirect conversion detector having, for example, a grid, a scintillator array, and a photosensor array. The scintillator array has multiple scintillators, and the scintillators have scintillator crystals that output light with a photon amount corresponding to the amount of incident X-rays. The grid is arranged on the X-ray incident side of the scintillator array and has an X-ray shielding plate that has the function of absorbing scattered X-rays.

[0020] The grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal according to the amount of light, and includes a photosensor such as a photomultiplier tube (PMT). The X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into an electrical signal. The X-ray detector 12 may also be a photon counting type X-ray detector. The X-ray detector 12 is an example of an X-ray detection unit.

[0021] The rotating frame 13 has a bore, and an X-ray tube 11 that generates X-rays is attached to it. Specifically, the rotating frame 13 is a cylindrical frame that supports the X-ray tube 11 and the X-ray detector 12 so that they face each other, and rotates the X-ray tube 11 and the X-ray detector 12 using a control device 18, which will be described later. The rotating frame 13 is rotatably supported on the fixed frame 5 via support bearings. The rotating frame 13 receives power from a drive mechanism of the control device 18 and rotates around a rotation axis R1 at a constant angular velocity.

[0022] The rotating frame 13 has at least one opening on a surface along the rotation axis (Z axis). That is, at least one opening is provided on a side surface of the rotating frame 13 that is parallel to the rotation axis (Z axis). The installation position of the opening on the side surface of the rotating frame 13 is shown, for example, by IL in FIG. 2. Note that the installation position of the opening is not limited to that shown in FIG. 2 and can be changed as appropriate depending on the relative positional relationship with the various units mounted on the rotating frame 13. Furthermore, for example, when two openings are provided on the rotating frame 13, the openings are arranged, for example, at two installation positions facing each other with the rotation axis of the rotating frame 13 as the center of symmetry. The shape of the openings will be described later.

[0023] The rotating frame 13 is further equipped with and supports an X-ray high voltage generator 17 and a DAS 21 in addition to the X-ray tube 11 and the X-ray detector 12. The rotating frame 13 is housed in a substantially cylindrical housing having a bore that forms the imaging space. The central axis of the bore coincides with the rotation axis R1 of the rotating frame 13.

[0024] The detection data generated by the DAS 21 is transmitted by optical communication from a transmitter having, for example, a light-emitting diode (LED) to a receiver having a photodiode provided in a non-rotating portion of the gantry 10 (for example, the fixed frame 5), and then transferred 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 used.

[0025] The X-ray high voltage device 17 has electrical circuits such as a transformer and a rectifier, and includes a high voltage generator having the function of generating a high voltage to be applied to the X-ray tube 11 and a filament current to be supplied to the X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays irradiated 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 17 may be provided on the rotating frame 13, or on the fixed frame 5 side of the gantry device 10.

[0026] The control device 18 has a processing circuit having a CPU (Central Processing Unit) and the like, and a drive mechanism for a motor, an actuator, etc. The processing circuit has, as hardware resources, a processor such as a CPU or an MPU (Micro Processing Unit) and a memory such as a ROM (Read Only Memory) or RAM (Random Access Memory).

[0027] The control device 18 may also be realized by an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), other complex programmable logic devices (CPLD), or simple programmable logic devices (SPLD). The control device 18 controls the X-ray high voltage device 17, the DAS 21, etc. in accordance with commands from the console device 40. The processor realizes the above control by reading and executing programs stored in the memory.

[0028] The control device 18 also has a function of receiving input signals from the console device 40 or an input interface attached to the gantry device 10 and controlling the operation of the gantry device 10 and the bed device 30. For example, the control device 18 receives input signals and controls the rotation of the rotating frame 13, the tilt of the gantry device 10, and the operation of the bed device 30 and the tabletop 33.

[0029] The control of tilting the gantry 10 may be achieved by the control device 18 rotating the rotation frame 13 around the horizontal axis R2 based on inclination angle (tilt angle) information input through an input interface attached to the gantry 10. The control device 18 may be provided in the gantry 10 or in the console device 40. The control device 18 may be configured to directly incorporate the program into the circuitry of the processor instead of storing the program in the memory. In this case, the processor realizes the above control by reading and executing the program incorporated in the circuitry.

[0030] The collimator 19 is a lead plate or the like for constricting the X-rays transmitted through the wedge 20 to an X-ray irradiation range, and a slit is formed by combining a plurality of lead plates or the like.

[0031] The wedge 20 is a filter for adjusting the amount of X-rays irradiated from the X-ray tube 11. Specifically, the wedge 20 is a filter that transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. The wedge 20 is, for example, a wedge filter or a bow-tie filter, and is a filter made by processing aluminum to have a predetermined target angle and a predetermined thickness.

[0032] The DAS 21 has an amplifier that amplifies the electrical signals output from each X-ray detection element of the X-ray detector 12 and an A / D converter that converts the electrical signals into digital signals, and generates detection data. The detection data generated by the DAS 21 is transferred to the console device 40. The DAS 21 is also an example of a data acquisition unit.

[0033] The bed device 30 is a device on which the subject P to be scanned is placed and moved, and includes a base 31, a bed driving device 32, a top 33, and a top support frame 34. The base 31 is a housing that supports the top support frame 34 so that it can move vertically. The bed driving device 32 is a motor or actuator that moves the top 33, on which the subject P is placed, in the longitudinal direction of the top 33. The bed driving device 32 moves the top 33 under the control of the console device 40 or the control device 18. The top 33, which is provided on the upper surface of the top support frame 34, is a plate on which the subject P is placed. Note that the bed driving device 32 may move the top support frame 34 in addition to the top 33 in the longitudinal direction of the top 33.

[0034] The console device 40 has a memory 41, a display 42, an input interface 43, and a processing circuit 44. Data communication between the memory 41, the display 42, the input interface 43, and the processing circuit 44 is performed via a bus (BUS).

[0035] The memory 41 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an integrated circuit storage device that stores various types of information. The memory 41 stores, for example, projection data and reconstructed image data. In addition to an HDD or an SSD, the memory 41 may be a portable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a flash memory, or a drive that reads and writes various types of information from and to a semiconductor memory element such as a RAM (Random Access Memory). The storage area of ​​the memory 41 may be located within the X-ray CT apparatus 1 or in an external storage device connected via a network. The memory 41 also stores a control program according to this embodiment.

[0036] The display 42 displays various types of information. For example, the display 42 outputs medical images (CT images) generated by the processing circuitry 44, a GUI (Graphical User Interface) for receiving various operations from the operator, and the like. For example, the display 42 may be a liquid crystal display (LCD), a cathode ray tube (CRT), an organic electroluminescence display (OLED), a plasma display, or any other display, as appropriate. The display 42 may also be provided on the gantry device 10. The display 42 may also be a desktop type, or may be configured as a tablet terminal or the like capable of wireless communication with the console device 40 main body.

[0037] The input interface 43 accepts various input operations from the operator, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 44. For example, the input interface 43 accepts from the operator acquisition conditions for acquiring projection data, reconstruction conditions for reconstructing CT images, image processing conditions for generating post-processed images from CT images, etc. As the input interface 43, for example, a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, etc. can be used as appropriate.

[0038] In this embodiment, the input interface 43 is not limited to one having physical operation components such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. For example, an example of the input interface 43 also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to the processing circuit 44. The input interface 43 may also be provided in the gantry device 10. The input interface 43 may also be configured as a tablet terminal or the like that is capable of wireless communication with the console device 40 main body.

[0039] The processing circuitry 44 controls the overall operation of the X-ray CT apparatus 1 in response to electrical signals of input operations output from the input interface 43. For example, the processing circuitry 44 has, as hardware resources, processors such as a CPU, MPU, and GPU (Graphics Processing Unit), and memories such as ROM and RAM. The processing circuitry 44 executes a system control function 441, a preprocessing function 442, and a reconstruction processing function 443 by the processor that executes programs loaded in the memory.

[0040] The processing circuit 44 that executes the system control function 441, the preprocessing function 442, and the reconstruction processing function 443 respectively corresponds to a system control unit, a preprocessing unit, and a reconstruction unit. Note that each of the functions 441 to 443 is not limited to being realized by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each of the functions 441 to 443.

[0041] The processing circuitry 44 controls each function of the processing circuitry 44 based on an input operation received from an operator via the input interface 43 using the system control function 441. Specifically, the system control function 441 reads out a control program stored in the memory 41, expands it on the memory in the processing circuitry 44, and controls each part of the X-ray CT apparatus 1 in accordance with the expanded control program. For example, the processing circuitry 44 controls each function of the processing circuitry 44 based on an input operation received from the operator via the input interface 43.

[0042] The processing circuitry 44 generates data by using a preprocessing function 442 that performs preprocessing such as logarithmic conversion, offset correction, inter-channel sensitivity correction, and beam hardening correction on the detection data output from the DAS 21. Note that data before preprocessing is referred to as raw data, and data after preprocessing is referred to as projection data.

[0043] The processing circuitry 44 generates CT image data by performing reconstruction processing using a filtered back projection (FBP) method, an iterative reconstruction method, or the like on the projection data generated by the preprocessing function 442 using a reconstruction processing function 443. The reconstruction processing function 443 stores the reconstructed CT image data in the memory 41.

[0044] The shape of the opening in the X-ray CT apparatus 1 according to this embodiment configured as described above will be described below. The edge of the opening on the rotation direction side (hereinafter referred to as the first edge) has a shape such that the timing of collision between the airflow passing through the opening from the inside of the rotating frame 13 to the outside of the rotating frame 13 (hereinafter referred to as the passing airflow) and the frame tip 15 facing the rotating frame 13 is shifted in the circumferential direction of the rotating frame 13.

[0045] For example, at least one of the first edge and the edge of the opening opposite to the rotation direction of the rotating frame 13 (hereinafter referred to as the second edge) is non-parallel to the rotation axis (Z axis). For example, the first edge and the second edge are continuously inclined with respect to the rotation axis (Z axis). Furthermore, the first edge has a first corner portion in the circumferential direction of the rotating frame 13, i.e., the rotation direction of the rotating frame 13. Note that the apex of the first corner portion of the first edge may be located in the center of the opening with respect to the direction of the rotation axis.

[0046] 3 is a diagram showing an example of the shape of opening 13A provided on the side surface of rotating frame 13 and an example of the change in noise intensity level relative value NIR according to the angle A of a first corner CA of opening 13A. As shown in FIG. 3, a first edge of opening 13A is non-parallel to the rotation axis (Z-axis) and is continuously inclined with respect to the rotation axis (Z-axis). Furthermore, the first edge of opening 13A has a first corner CA with respect to the circumferential direction of rotating frame 13, i.e., the rotation direction of rotating frame 13. In FIG. 3, the angle of the first corner CA is indicated by A. Furthermore, the apex of the first corner CA of the first edge of opening 13A is located at the center of opening 13A with respect to the direction of the rotation axis.

[0047] The relative acoustic power level NIR is the noise intensity relative to a conventional shape in which the opening shape is rectangular and the edge of the frame tip 15 (hereinafter referred to as the frame tip edge) is parallel to the rotation axis. The noise intensity NI of the conventional shape and the noise intensity NI' related to the opening 13A are calculated, for example, from the change in gas pressure over time obtained by computational fluid dynamics (CFD). The relative acoustic power level NIR is calculated by taking the logarithm of the ratio between the noise intensity NI of the conventional shape and the noise intensity NI' related to the opening 13A.

[0048] When the opening 13A has a first edge as shown in FIG. 3, at the first corner CA, the range AAR of the angle A at which noise is reduced compared to the conventional shape is a range of angles greater than 70° and less than 180° (70° < A < 180°). As shown in FIG. 3, at the minimum value of the relative acoustic power level NIR, the angle A is in the vicinity of 120°. Therefore, when the angle A of the first corner CA of the first edge in the opening 13A is set in the vicinity of 120°, the effect of reducing noise is maximized.

[0049] The second edge may have a shape such that the timing of the collision between the passing airflow and the frame tip 15 is shifted in the circumferential direction of the rotating frame 13. For example, the second edge is non-parallel to the rotation axis (Z-axis) and continuously inclined with respect to the rotation axis (Z-axis). Further, the second edge has a second corner with respect to the circumferential direction of the rotating frame 13, that is, the rotation direction of the rotating frame 13. Note that the apex at the second corner of the second edge may be located at the center in the direction of the rotation axis in the opening.

[0050] FIG. 4 is a diagram showing an example of the shape of the opening 13B provided on the side surface of the rotating frame 13 and an example of the change in the relative acoustic power level NIR according to the angle B of the second corner CB in the opening 13B. As shown in FIG. 4, the second edge in the opening 13B is non-parallel to the rotation axis (Z-axis) and continuously inclined with respect to the rotation axis (Z-axis). Further, the second edge in the opening 13B has a second corner CB with respect to the circumferential direction of the rotating frame 13, that is, the rotation direction of the rotating frame 13. In FIG. 3, the angle of the second corner CB is indicated by B. Also, the apex at the second corner CB of the second edge in the opening 13B is located at the center in the direction of the rotation axis in the opening 13B.

[0051] When the opening 13B has a second edge as shown in FIG. 4, at the second corner CB, the range BAR of the angle B at which noise is reduced compared to the conventional shape is a range of angles less than 120° (B < 120°).

[0052] FIG. 5 shows an example of the shape of an opening 13C provided on a side surface of the rotating frame 13 and an example of the change in the acoustic power level relative value NIR depending on the angle C of a second corner CC of the opening 13C. As shown in FIG. 5, the second edge of the opening 13C is non-parallel to the rotation axis (Z-axis) and is continuously inclined with respect to the rotation axis (Z-axis). The second edge of the opening 13C has a second corner CC with respect to the circumferential direction of the rotating frame 13, i.e., the rotation direction of the rotating frame 13. In FIG. 5, the angle of the second corner CC is indicated by C. The apex of the second corner CC of the second edge of the opening 13C is located at the center of the opening 13C with respect to the direction of the rotation axis.

[0053] When the opening 13C has a second edge as shown in Figure 5, the range CAR of angle C at the second corner CC in which noise is reduced compared to the conventional shape is an angle range less than 120° (C<120°).

[0054] Furthermore, the first edge and second edge of the opening may have shapes such that the timing of collision between the passing airflow and frame tip 15 is offset relative to the circumferential direction of rotating frame 13. For example, the first edge and second edge of the opening are not parallel to the rotation axis (Z-axis) and are continuously inclined relative to the rotation axis (Z-axis). In this case, the first edge has a first corner relative to the circumferential direction of rotating frame 13, i.e., the rotation direction of rotating frame 13. Note that the apex of the first corner of the first edge may be located in the center of the opening relative to the direction of the rotation axis (Z-axis).

[0055] The second edge has a second corner portion in the circumferential direction of the rotating frame 13, i.e., in the rotation direction of the rotating frame 13. The apex of the second corner portion of the first edge may be located in the center of the opening in the direction of the rotation axis (Z-axis).

[0056] 6 is a diagram showing an example of the shape of an opening 13D provided on a side surface of the rotating frame 13, and an example of the change in the acoustic power level relative value NIR according to the angle D between a first corner CDF and a second corner CDR of the opening 13D. As shown in FIG. 6, the first edge and the second edge of the opening 13D are not parallel to the rotation axis (Z axis) and are continuously inclined with respect to the rotation axis (Z axis). Furthermore, the first edge of the opening 13D has a first corner CDF in the circumferential direction of the rotating frame 13, i.e., the rotation direction of the rotating frame 13.

[0057] 6 has a second corner portion CDR in the circumferential direction of the rotating frame 13, i.e., the rotation direction of the rotating frame 13. In FIG. 6, the angle between the first corner portion CDF and the second corner portion CDR is indicated by D. The vertices of the first corner portion CDF of the first edge and the second corner portion CDR of the second edge in the opening 13D are located in the center of the opening 13D with respect to the direction of the rotation axis.

[0058] 6, the range DAR of the angle D at the first corner CDF and the second corner CDR, in which noise is reduced compared to the conventional shape, is an angle range of less than 120° (D<120°). Note that the first corner CDF and the second corner CDR may have different angles as long as they are both less than 120°.

[0059] 7 is a diagram showing an example of the shape of opening 13E provided in the side surface of rotating frame 13, and an example of the change in the acoustic power level relative value NIR according to the angle E between a first corner CEF and a second corner CER of opening 13E. As shown in FIG. 7, the first edge and the second edge of opening 13E are not parallel to the rotation axis (Z axis) and are continuously inclined with respect to the rotation axis (Z axis). Furthermore, the first edge of opening 13E has a first corner CEF with respect to the circumferential direction of rotating frame 13, i.e., the rotation direction of rotating frame 13.

[0060] Furthermore, the second edge of opening 13E has a second corner portion CER that is convex in the direction opposite to the rotation direction of rotating frame 13. In Fig. 7, the angle between first corner portion CEF and second corner portion CER is indicated by E. Furthermore, the apex of first corner portion CEF of the first edge and second corner portion CER of the second edge of opening 13E is located in the center of opening 13E with respect to the direction of the rotation axis.

[0061] 7, the range of angle E EAR between the first corner CEF and the second corner CER, within which noise is reduced compared to the conventional shape, is less than 120° (E<120°). Note that the angles of the first corner CEF and the second corner CER may be different as long as they are both less than 120°.

[0062] 8 is a diagram showing an example of the shape of an opening 13F provided on a side surface of the rotating frame 13 and an example of the change in the acoustic power level relative value NIR according to the angle F between a first corner CFF and a second corner CFR of the opening 13F. As shown in FIG. 8, the first edge and the second edge of the opening 13F are not parallel to the rotation axis (Z axis) and are continuously inclined with respect to the rotation axis (Z axis). The first edge of the opening 13F has a first corner CFF in the circumferential direction of the rotating frame 13, i.e., the rotation direction of the rotating frame 13. The apex of the first corner CFF of the first edge of the opening 13F is located at a position offset along a predetermined direction of the rotation axis from the center of the opening 13F in the direction of the rotation axis.

[0063] Furthermore, the second edge of the opening 13F has a second corner portion CFR in the circumferential direction of the rotating frame 13, i.e., in the rotation direction of the rotating frame 13. In Fig. 8, the angle between the first corner portion CFF and the second corner portion CFR is indicated by F. Furthermore, the apex of the second edge at the second corner portion CER is located at a position offset from the center of the opening 13F in the direction of the rotation axis along the opposite direction to the predetermined direction.

[0064] When the opening 13F has a first edge and a second edge as shown in FIG. 8, the range EAR of the angle F between the first corner CFF and the second corner CFR, in which noise is reduced compared to the conventional shape, is an angle range less than 80° (F<80°).

[0065] The X-ray CT apparatus 1 according to the embodiment described above includes a rotating frame 13 to which an X-ray tube 11 that generates X-rays is attached, and a support frame that supports the rotating frame 13 so that the rotating frame 13 can rotate around a rotation axis in a predetermined rotation direction, the rotating frame 13 having at least one opening on a surface along the rotation axis, and at least one of a first edge on the rotation direction side of the opening and a second edge on the opposite side to the rotation direction of the opening is non-parallel to the rotation axis. Furthermore, in the X-ray CT apparatus 1 according to the embodiment, at least one of the first edge and the second edge is continuously inclined with respect to the rotation axis.

[0066] Furthermore, in the X-ray CT apparatus 1 according to the embodiment, the first edge has a first corner portion with respect to the circumferential direction of the rotating frame 13. Furthermore, in this X-ray CT apparatus 1, the apex of the first corner portion is located at the center of the opening with respect to the direction of the rotation axis. Furthermore, in this X-ray CT apparatus 1, the angle of the first corner portion ranges from an angle exceeding 70° to an angle less than 180°.

[0067] Furthermore, in the X-ray CT apparatus 1 according to the embodiment, the second edge has a second corner portion with respect to the circumferential direction of the rotating frame 13. Furthermore, in this X-ray CT apparatus 1, the apex of the second corner portion is located at the center of the opening with respect to the direction of the rotation axis. Furthermore, in this X-ray CT apparatus 1, the angle range of the second corner portion is a range of angles less than 120°. Note that in this X-ray CT apparatus 1, the angle ranges of the first corner portion CDF and the second corner portion CDR are both less than 120°, and the angles of the first corner portion CDF and the second corner portion CDR may be different from each other. Furthermore, in this X-ray CT apparatus 1, the second edge has a second corner portion CER that is convex in the direction opposite to the rotation direction of the rotating frame 13, and the apex of the second corner portion CER is located at the center of the opening with respect to the direction of the rotation axis. In this case, the range of the angles at the first corner portion CEF and the second corner portion CER are both less than 120°, and the angle of the first corner portion CEF and the angle of the second corner portion CER may be different from each other.

[0068] In the X-ray CT apparatus 1 according to the embodiment, the apex of the first corner is located at a position offset from the center of the opening in the direction of the rotation axis along a predetermined direction of the rotation axis, and the apex of the second corner is located at a position offset from the center along a direction opposite to the predetermined direction. In the X-ray CT apparatus 1, the angle between the first corner and the second corner is within an angle range of less than 80°.

[0069] 9 is a diagram showing an example of an airflow (arrows: streamline vectors) flowing out from a rectangular opening AP as a comparative example. As shown in FIG. 9, the airflow flows outward in the radial direction of the rotating frame (hereinafter referred to as the radially outward direction). Furthermore, when the rotating frame is rotating, that is, when the X-ray computed tomography apparatus is operating, the airflow moves in the circumferential direction of the rotating frame 13 while flowing outward in the radially outward direction.

[0070] As shown in Figure 9, the airflow flowing out from the opening AP can be broadly divided into two types (airflow A and airflow B). Airflow A is the main type of airflow on the front side of the opening AP in the rotation direction. Airflow A is an airflow that flows out in a substantially radially outward direction relative to the outer circumferential surface of the rotating frame. Airflow B is the main type of airflow on the opposite side of the opening AP in the rotation direction of the rotating frame. The airflow flowing out from the opening AP flows in a radially outward direction, but this airflow moves together with the rotating frame RB. Therefore, a negative pressure region is generated on the opposite side of the rotation direction (hereinafter referred to as the counter-rotation side) of the airflow flowing out from the opening AP. Due to the action of the negative pressure region, the airflow on the counter-rotation side of the opening AP flows in a radially outward direction and then is suddenly bent toward the negative pressure region generated on the counter-rotation side of the opening AP. As a result, airflow B becomes a large vortex behind the opening AP, as shown in Figure 9.

[0071] As a comparative example, Figure 10 shows a schematic diagram illustrating how airflow A and airflow B collide with the frame tip FB as the rotating frame rotates. Each of airflow A and airflow B generates very large pressure fluctuations when they collide with the frame tip FB, which generates aerodynamic noise due to fluid dynamics.

[0072] As shown in Fig. 9, the shape of the conventional opening AP as a comparative example is a rectangle with sides approximately parallel to the rotation axis direction. Therefore, as shown in Fig. 10, airflow A and airflow B are uniformly discharged from opening AP along the rotation axis direction and collide with the frame tip. In other words, for airflow A and airflow B, a series of airflows flowing radially outward along the rotation axis direction collide with the frame tip FB at the same time. This results in very large pressure fluctuations in the airflow.

[0073] The pressure fluctuations occur at a timing that depends on the rotation of the rotating frame RB, so the noise caused by the pressure fluctuations is classified as narrowband noise, which occurs at frequencies that are integer multiples of the rotation frequency of the rotating frame RB.

[0074] 11 is a diagram showing an example of airflow A and airflow B at the opening 13D corresponding to FIG. 6 in the embodiment. As shown in FIG. 11, according to the X-ray CT apparatus 1 of the present embodiment, the timing at which the airflow A and airflow B flowing out from the opening 13D collide with the frame tip 15 can be shifted with respect to the direction of the rotation axis (Z axis). On the other hand, in the comparative example shown in FIGS. 9 and 10, the streamline of the airflow A and the streamline of the entrained airflow B are uniformly aligned with the direction of the rotation axis. Therefore, in the comparative example, the energy of the collision with the frame tip 15 is greater and the pressure fluctuation is also greater than in the present embodiment.

[0075] On the other hand, according to the X-ray CT apparatus 1 of this embodiment, as shown in FIGS. 3 to 8, at least one of the first edge and the second edge of the opening is continuously inclined with respect to the direction of the rotation axis so as to continuously shift the streamline of the airflow with respect to the rotation direction. FIG. 12 is a diagram showing an example of the change in pressure at the frame tip 15 in the embodiment and the comparative example. The change in pressure at the frame tip 15 is calculated, for example, by computational fluid dynamics (CFD). As shown in FIG. 12, the change in pressure (pressure fluctuation) at the frame tip 15 in the embodiment is smaller than in the comparative example. Therefore, according to the X-ray CT apparatus 1 of this embodiment, the pressure fluctuation can be kept smaller than in the conventional comparative example, and as a result, noise can be reduced.

[0076] As an application example of this embodiment, at least one of the first edge and the second edge of the opening may have a stepped shape (step-like shape change) such that the timing of collision between the passing airflow and the frame tip 15 is shifted in the circumferential direction of the rotating frame 13. This application example can obtain the same effect as this embodiment.

[0077] As described above, the X-ray CT apparatus 1 according to this embodiment can reduce noise while maintaining cooling performance without blocking the opening.

[0078] (Variation) In this modified example, as the second edge at the opening, it has a terminal corner with respect to the circumferential direction of the rotating frame 13, and at the tip of the support frame (frame tip 15) facing the rotating frame 13, as a shape on the side opposite to the rotation direction, it has a tip corner with respect to the circumferential direction of the rotating frame 13. At this time, the terminal corner and the tip corner may be non-parallel to the rotation axis and continuously inclined with respect to the rotation axis. Also, the apex at the tip corner may be located at the center with respect to the direction of the rotation axis at the opening.

[0079] FIG. 13 is a diagram showing an example of the shape of the tip corner TC at the opening 13D and the frame tip 15 shown in FIG. 6, and an example of the change in the relative value NIR of the acoustic power level according to the angle G of the tip corner TC at the frame tip 15. The second edge of the opening 13D shown in FIG. 13 has a terminal corner EC with respect to the circumferential direction of the rotating frame 13. As shown in FIG. 13, the terminal corner EC and the tip corner TC are non-parallel to the rotation axis and continuously inclined with respect to the rotation axis. Also, as shown in FIG. 13, the apex at the tip corner TC is located at the center with respect to the direction of the rotation axis. In FIG. 13, the angle at the tip corner TC is indicated by G.

[0080] When the opening 13D has the first edge and the second edge as shown in FIG. 6, and the tip corner TC at the frame tip 15 has the shape as shown in FIG. 13, in the tip corner TC, the range GAR of the angle G at which the noise is reduced compared to the conventional shape is a range of angles exceeding 60° to less than 180° (60° < G < 180°). As shown in FIG. 13, at the minimum value of the relative value NIR of the acoustic power level, the angle G is around 120°. Therefore, when the angle G of the tip corner TC is set around 120° with respect to the opening 13D, the effect of reducing noise is maximized.

[0081] FIG. 14 is a diagram showing an example of the shape of the opening 13C shown in FIG. 5 and the tip corner TC at the frame tip 15, and an example of the change in the relative value NIR of the acoustic power level according to the angle H of the tip corner TC at the frame tip 15. In the opening 13C shown in FIG. 14, the second edge has a terminal corner EC with respect to the circumferential direction of the rotating frame 13. As shown in FIG. 14, the first edge in the opening 13C is parallel to the rotation axis. On the other hand, the tip corner TC is non-parallel to the rotation axis and continuously inclined with respect to the rotation axis. Further, as shown in FIG. 14, the apex of the tip corner TC is located at the center with respect to the direction of the rotation axis. In FIG. 14, the angle at the tip corner TC is indicated by H.

[0082] When the opening 13C has the first edge and the second edge as shown in FIG. 5, and the tip corner TC at the frame tip 15 has the shape as shown in FIG. 14, in the tip corner TC, the range HAR of the angle G at which the noise is reduced compared to the conventional shape is the range of angles exceeding 50° to less than 180° (50° < H < 180°). As shown in FIG. 14, at the minimum value of the relative value NIR of the acoustic power level, the angle H is in the vicinity of 120°. Therefore, when the angle H of the tip corner TC is set in the vicinity of 120° with respect to the opening 13C, the effect of reducing noise is maximized.

[0083] In the X-ray CT apparatus 1 according to the modification described above, the second edge has a terminal corner EC with respect to the circumferential direction of the rotating frame 13, and the third edge on the opposite side of the rotation direction at the frame tip 15 has a tip corner TC with respect to the circumferential direction of the rotating frame 13. Further, in the present X-ray CT apparatus 1, the terminal corner EC and the tip corner TC are non-parallel to the rotation axis and are continuously inclined with respect to the rotation axis, and the apex of the tip corner TC is located at the center with respect to the direction of the rotation axis.

[0084] In the X-ray CT apparatus 1 according to the modified example, when the first edge is parallel to the rotation axis, the angle at the tip corner TC ranges from an angle exceeding 50° to an angle less than 180°. In the present X-ray CT apparatus 1, when the first edge and the second edge are not parallel to the rotation axis and are continuously inclined with respect to the rotation axis, the angle at the tip corner TC ranges from an angle exceeding 60° to an angle less than 180°.

[0085] The effects of this modification are similar to those of the embodiment, and therefore a description thereof will be omitted. Note that the shape of the opening in this modification is not limited to the above description, and may be, for example, the shape of the opening as shown in Figures 4, 7, and 8.

[0086] When the technical ideas of the embodiments and the like are realized in a gantry 10, the gantry 10 includes a rotating frame 13 to which an X-ray tube 11 that generates X-rays is attached, and a support frame that supports the rotating frame 13 so that the rotating frame 13 can rotate around a rotation axis in a predetermined rotation direction, the rotating frame 13 has at least one opening on a surface along the rotation axis, and at least one of a first edge on the rotation direction side of the opening and a second edge on the opposite side to the rotation direction of the opening is non-parallel to the rotation axis. The effects of the gantry 10 are similar to those of the embodiments and the like, so a description thereof will be omitted.

[0087] According to at least the embodiment and modifications described above, it is possible to reduce noise while maintaining the cooling function for the various units mounted on the rotating frame 13.

[0088] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0089] 1 X-ray CT device 5 Fixed Frame 6 Standing frame 7 Base Stand 8 Mounting arm 10 Mounting device 11 X-ray tube 12 X-ray detector 13 Rotating Frame 13A, 13B, 13C, 13D, 13E, 13F opening 15 Frame tip 17. X-ray high voltage device 18 Control Device 19 Collimator 20 Wedge 21 DAS (Data Acquisition System) 30 Bed Device 31 Foundation 32 Bed drive unit 33 Top plate 34 Top plate support frame 40 Console device 41 memory 42 Display 43 Input Interface 44 Processing circuit 441 System Control Functions 442 Pre-processing function 443 Reconstruction Processing Function

Claims

1. a rotating frame on which an X-ray tube for generating X-rays is mounted; a support frame that supports the rotating frame rotatably around a rotation axis in a predetermined rotation direction, the rotating frame has at least one opening in a side surface of the rotating frame; At least one of a first edge on a front side of the opening in the rotation direction and a second edge on a rear side of the opening in the rotation direction is non-parallel to the rotation axis, the first edge has a first corner portion that is convex toward the front side in the rotation direction; X-ray computed tomography equipment.

2. the first corner portion is located at the center of the width of the rotating frame in a direction perpendicular to the rotation direction in the opening portion; 2. The X-ray computed tomography apparatus according to claim 1.

3. the angle between the two sides forming the first corner is an angle included in the range of an angle exceeding 70° to an angle less than 180°; 3. The X-ray computed tomography apparatus according to claim 2.

4. A rotating frame to which an X-ray tube that generates X-rays is attached; a support frame that supports the rotating frame rotatably around a rotation axis in a predetermined rotation direction, the rotating frame has at least one opening in a side surface of the rotating frame; At least one of a first edge on a front side of the opening in the rotation direction and a second edge on a rear side of the opening in the rotation direction is non-parallel to the rotation axis, the second edge has a second corner portion that is convex toward the rear side in the rotation direction; X-ray computed tomography equipment.

5. the second corner portion is located at the center of the width of the rotating frame in a direction perpendicular to the rotation direction in the opening portion; 5. The X-ray computed tomography apparatus according to claim 4.

6. The angle between the two sides forming the second corner portion is an angle included in a range of angles less than 120°.

6. An X-ray computed tomography apparatus according to claim 5.

7. The first edge has a first corner portion that is convex toward the forward side in the rotation direction, The angle between the two sides forming the first corner portion is an angle less than 120°, The angle between the two sides forming the second corner portion is an angle less than 120°, an angle between the two sides forming the first corner portion and an angle between the two sides forming the second corner portion are different from each other; 6. An X-ray computed tomography apparatus according to claim 5.

8. The second edge has a second corner portion that is convex toward the rear side in the rotation direction, the first corner portion is located at a position offset along a predetermined direction of the rotation axis from a center of a width of the rotating frame along a direction perpendicular to the rotation direction in the opening, the second corner portion is located at a position offset from the center along a direction opposite to the predetermined direction; 2. The X-ray computed tomography apparatus according to claim 1.

9. The angle between the two sides forming the first corner portion is an angle less than 80°, The angle between the two sides forming the second corner portion is an angle less than 80°.

9. An X-ray computed tomography apparatus according to claim 8.

10. A rotating frame to which an X-ray tube for generating X-rays is attached; a support frame that supports the rotating frame rotatably around a rotation axis in a predetermined rotation direction, the rotating frame has at least one opening in a side surface of the rotating frame; At least one of a first edge on a front side of the opening in the rotation direction and a second edge on a rear side of the opening in the rotation direction is non-parallel to the rotation axis, the support frame includes a fixed frame that supports the rotating frame rotatably about a rotation axis via a bearing, and a pair of base arms that support the fixed frame tiltably about a horizontal axis that is perpendicular to the rotation axis and parallel to a floor surface, At the tip of the gantry arm, a third edge on the rear side in the rotation direction has a third corner portion that is convex toward the rear side in the rotation direction. X-ray computed tomography equipment.

11. the third corner portion is located at the center of the width of the pedestal arm along a direction perpendicular to the rotation direction; The X-ray computed tomography apparatus according to claim 10.

12. the first edge and the second edge are non-parallel to the rotation axis; The angle between the two sides forming the third corner is an angle included in the range of an angle exceeding 60° to an angle less than 180°.

12. The X-ray computed tomography apparatus according to claim 11.

13. the first edge is parallel to the rotation axis, and the angle between the two sides forming the third corner is an angle included in the range of an angle exceeding 50° to an angle less than 180°; 12. The X-ray computed tomography apparatus according to claim 11.

14. The support frame has a fixed frame that rotatably supports the rotating frame around a rotation axis via bearings, and a pair of base arms that support the fixed frame so that it can tilt around a horizontal axis that is perpendicular to the rotation axis and parallel to the floor surface, When the rotating frame rotates, The tip of the pedestal arm faces the opening, an airflow passing through the opening from the inside of the rotating frame to the outside of the rotating frame collides with a tip of the pedestal arm; a timing at which the airflow collides with the tip of the pedestal arm is shifted relative to the direction of the rotation axis due to a shape of the first edge of the opening; 2. The X-ray computed tomography apparatus according to claim 1.

15. A rotating frame to which an X-ray tube for generating X-rays is attached; a support frame that supports the rotating frame rotatably around a rotation axis in a predetermined rotation direction, the support frame includes a fixed frame that supports the rotating frame rotatably about a rotation axis via a bearing, and a pair of base arms that support the fixed frame tiltably about a horizontal axis that is perpendicular to the rotation axis and parallel to a floor surface, the rotating frame has at least one opening in a side surface of the rotating frame; At least one of a first edge on a front side of the opening in the rotation direction and a second edge on a rear side of the opening in the rotation direction is non-parallel to the rotation axis, At least one of the first edge and the second edge has a stepped shape toward the front side in the rotation direction, When the rotating frame rotates, The tip of the pedestal arm faces the opening, an airflow passing through the opening from the inside of the rotating frame to the outside of the rotating frame collides with a tip of the pedestal arm; a timing at which the airflow collides with the tip of the pedestal arm is shifted with respect to the direction of the rotation axis due to a shape of at least one of the first edge and the second edge of the opening; X-ray computed tomography equipment.

16. a rotating frame on which an X-ray tube for generating X-rays is mounted; a support frame that supports the rotating frame rotatably around a rotation axis in a predetermined rotation direction, the rotating frame has at least one opening in a side surface of the rotating frame; At least one of a first edge on a front side of the opening in the rotation direction and a second edge on a rear side of the opening in the rotation direction is non-parallel to the rotation axis, the first edge has a first corner portion that is convex toward the front side in the rotation direction; Mounting device.

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