Vibration measuring apparatus of x-ray computer tomographic diagnostic apparatus

Abstract

To provide a vibration measuring apparatus of an X-ray computer tomographic diagnostic apparatus that can improve quality.SOLUTION: A vibration measuring apparatus 30 of an X-ray computer tomographic diagnostic apparatus includes: a housing; a trestle 13 that rotates in the housing; and an X-ray tube 15 mounted on the trestle 13. A detector 33 is arranged at least either on the trestle 13 or the X-ray tube 15 for detecting vibration in a state that the trestle 13 rotates.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a vibration measuring device for an X-ray computed tomography diagnostic apparatus. [Background technology]

[0002] Generally, a structure has a natural resonance frequency, and in this resonance frequency range, a resonance phenomenon occurs, resulting in large vibrations and noise, and in some cases, the structure itself may be damaged.

[0003] In a computed tomography (CT) system, a heavy X-ray tube and a cooling device are mounted on a stand called a gantry, and the stand is rotated within the housing to irradiate the subject with X-rays and take cross-sectional images of the subject.

[0004] The X-ray tube has an anode rotation mechanism, the cooling device has a circulation pump for circulating the coolant, and the gantry itself also rotates, so vibrations occur in the X-ray CT scanner.

[0005] Traditionally, X-ray CT systems required low output from the X-ray tube, so the X-ray tube was small, had low rigidity, and was also light in mass. Therefore, changes in vibration values ​​caused by the operation of the X-ray tube had little impact on the entire X-ray CT system. In recent years, with the improvement in the performance of X-ray CT systems, there has been a demand for higher output from X-ray tubes, and in response to this demand, X-ray tubes have become larger, more rigid, and more massive. Furthermore, the rotation speed of the gantry has also increased, resulting in greater changes in vibration values ​​caused by the operation of the X-ray tube.

[0006] The vibration frequency of a vibration source usually does not change unless there is deformation or change in rigidity of the material that constitutes the vibration source.

[0007] However, when generating X-rays, 99% of the electrical energy supplied to an X-ray tube is converted into heat, and this heat causes deformation and changes in rigidity of the material in the anode part of the X-ray tube, resulting in a change in the resonant frequency.

[0008] This change in resonant frequency causes a change in the number of vibrations generated by the vibration source, and if this change interferes with the resonant frequency of another structure, a resonance phenomenon will occur, resulting in abnormal noise, fluctuations in tube current due to the vibration of the X-ray tube filament, and over time damage. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2020-13715 A Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a vibration measuring device for an X-ray computed tomography diagnostic apparatus that can improve quality. [Means for solving the problem]

[0011] This embodiment is a vibration measuring device for an X-ray computed tomography diagnostic apparatus that includes a housing, a gantry that rotates within the housing, and an X-ray tube mounted on the gantry. The device includes a detector that is disposed on at least one of the gantry and the X-ray tube and detects vibrations while the gantry is rotating. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view of an X-ray computed tomography diagnostic apparatus showing an embodiment. [Diagram 2] FIG. 2 is a front view of a rotating part of the X-ray computed tomography diagnostic apparatus. [Diagram 3] FIG. 2 is a cross-sectional view of a rotating part of the X-ray computed tomography diagnostic apparatus. [Figure 4] FIG. 2 is a block diagram of a vibration measuring device of the above X-ray computed tomography diagnostic apparatus. [Diagram 5]13A and 13B show examples of graphically displaying the measurement results of the vibration measuring device, in which (a) is an explanatory diagram showing a graphical display of the time series progression of detection data synchronized with the rotation of the gantry in a first state in which the X-ray tube is not emitting, and (b) is an explanatory diagram showing a graphical display of the time series progression of detection data synchronized with the rotation of the gantry in a second state in which the X-ray tube is emitting. [Figure 6] FIG. 4 is a waveform diagram showing the measurement results of the vibration measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment will be described with reference to the drawings.

[0014] FIG. 1 shows a perspective view of a computed tomography diagnostic apparatus (hereinafter referred to as an X-ray CT (Computed Tomography) apparatus) 10.

[0015] The X-ray CT device 10 includes a housing 11 that forms the outer shell of the X-ray CT device 10. An introduction port 12 for introducing a subject is provided in the center of the housing 11. Although not shown, the X-ray CT device 10 also includes a bed on which the subject is placed and introduced into the introduction port 12.

[0016] 2 shows a front view of the rotating part of the X-ray CT device 10, and FIG. 3 shows a cross-sectional view of the rotating part of the X-ray CT device 10. As shown in FIG.

[0017] Within the housing 11, a frame (rotating frame) 13, which is a rotating part and is called a gantry, is disposed so as to be rotatable about a rotation axis 14. The rotation axis 14 coincides with the central axis of the introduction port 12 of the housing 11. The frame 13 is provided in a ring shape, and rotates about the rotation axis 14 by a rotation drive mechanism having a motor as a drive part, not shown. The frame 13 rotates at high speed, for example, one rotation every 0.5 seconds.

[0018] An X-ray tube 15, an X-ray detector 16, a cooling device 17, etc. are mounted on the inner wall of the frame on the outer periphery of the gantry 13. The X-ray tube 15, the X-ray detector 16, the cooling device 17, etc. rotate together with the gantry 13.

[0019] The X-ray tube 15 is attached to the inner wall of the frame on the outer periphery of the gantry 13, in the central region in the axial direction of the gantry 13. The X-ray tube 15 is a rotating anode type X-ray tube, and includes a cathode that emits electrons, an anode target that generates X-rays when electrons emitted from the cathode collide with the anode target, a rotor that supports the anode target and rotates, a coolant passage provided inside the rotor, a vacuum vessel 20 that houses these, an X-ray transmission window 21 that is provided in the vacuum vessel 20 and emits X-rays generated by the anode target to the outside, and a coil that generates a magnetic field that rotates the rotor from outside the vacuum vessel 20. A high-voltage generating power supply that applies a high voltage between the cathode and the anode target may be mounted on the gantry 13.

[0020] X-ray tube 15 is disposed so that the axial direction of the rotation axis of the rotor coincides with the axial direction of rotation axis 14 of gantry 13, and so that X-ray transparent window 21 faces rotation axis 14 of gantry 13. When viewed from the front side of gantry 13 (when viewed from the front side of X-ray CT device 10 in FIG. 1), the cathode, anode target, etc. of X-ray tube 15 are disposed on the front side (near side), and the rotor, coil, etc. of X-ray tube 15 are disposed on the rear side (rear side).

[0021] The X-ray detector 16 is disposed on the gantry 13 at a position facing the X-ray transmission window 21 of the X-ray tube 15 via the rotation axis 14 of the gantry 13. The X-ray detector 16 detects X-rays emitted from the X-ray tube 15 and transmitted through the subject, converts the detected X-rays into an electrical signal, and outputs the signal. The gantry 13 may be equipped with a power supply unit for operating the X-ray detector 16 and a data acquisition device for amplifying and A / D converting the electrical signal output from the X-ray detector 16.

[0022] The cooling device 17 is disposed on the inner wall of the frame on the outer periphery of the gantry 13, on the side of the X-ray tube 15. The cooling device 17 is connected to the coolant passage of the X-ray tube 15 by a connection tube 24, forming a circulation path for circulating the coolant between the cooling device 17 and the X-ray tube 15. The cooling device 17 includes a heat exchanger that cools the coolant by dissipating heat from the coolant circulated through the circulation path, and a circulation pump that circulates the coolant in the circulation path. A power supply unit that drives the fan of the heat exchanger and the circulation pump may be mounted on the gantry.

[0023] Although not shown in the figure, a slip ring is interposed between the stand 13 side and the housing 11 side that rotatably supports the stand 13, and this slip ring is configured to allow power and control signals to be supplied from the outside to the equipment mounted on the stand 13, and to allow signals from the equipment on the stand 13 side to be taken out to the outside.

[0024] FIG. 4 shows a block diagram of a vibration measuring device 30 of the X-ray CT device 10. As shown in FIG.

[0025] The vibration measuring device 30 includes an internal device section 31 arranged on the gantry 13, and an external device section 32 arranged outside the X-ray CT device .

[0026] The internal device section 31 includes a plurality of detectors 33, a data logger 34, and a communication section (internal communication section) 35. The internal device section 31 may operate using power supplied to the pedestal 13 side via a slip ring, or may operate using power from a battery placed in the pedestal 13.

[0027] The detector 33 is a three-dimensional acceleration sensor capable of detecting vibrations in the axial directions of the X-axis, Y-axis, and Z-axis. The detector 33 is disposed at each position such that the X-axis faces the rotation direction of the gantry 13, the Y-axis faces the axial direction of the gantry 13, and the Z-axis faces the center of the gantry 13. As shown in Figs. 2 and 3, the detector 33 is disposed at each measurement point, i.e., at the position where the X-ray tube 15 of the gantry 13 is disposed and at two positions in the axial direction of the rotation axis 14 of the gantry 13, a position near the X-ray transmission window 21 of the X-ray tube 15, the position of the X-ray detector 16, and the position of the surface of the cooling device 17. The detector 33 is preferably disposed at all of these measurement points, but may be disposed at at least one of them. In this case, the detector 33 is preferably disposed at the position of the X-ray tube 15 or the position of the gantry 13 where the X-ray tube 15 is disposed.

[0028] The data logger 34 stores the detection data detected by each detector 33 in chronological order in synchronization with the rotation of the gantry 13 .

[0029] The communication unit 35 transmits the detection data of each detector 33 stored in the data logger 34 to the external device unit 32 by wireless communication. When the communication unit included in the X-ray CT device 10 can be used, the communication unit of the X-ray CT device 10 may be used without using the communication unit 35.

[0030] The external device unit 32 includes a communication unit (external communication unit) 36, an acquisition unit 37, and a display processing unit 38. The external device unit 32 is composed of a computer, and includes a control unit that performs calculation processing according to a program, a storage unit that stores the program and data, and a monitor such as a liquid crystal display. The acquisition unit 37 and the display processing unit 38 are functions of the control unit.

[0031] The communication unit 36 ​​is capable of mutual communication with the communication unit 35 via wireless communication.

[0032] The acquisition unit 37 acquires, via the communication unit 36 ​​, detection data stored in the data logger 34 , and which is time-series detection data detected by the detector 33 in synchronization with the rotation of the gantry 13 .

[0033] The display processing unit 38 graphically displays (visualizes) the time series transition of the detection data acquired by the acquisition unit 37. The display includes displaying the change in vibration value in each of the X-axis, Y-axis, and Z-axis directions in a three-dimensional graphic (see FIG. 5), and displaying the change in vibration value in a time series in a two-dimensional graphic (see FIG. 6).

[0034] When vibration measurements are performed using the vibration measuring device 30, vibration measurements are performed in real time for each of a first state (first state in which the X-ray tube 15 is not emitting radiation) in which the gantry 13 is rotated and the operation of the X-ray tube 15, X-ray detector 16 and cooling device 17 is stopped, and a second state (second state in which the X-ray tube 15 is emitting radiation) in which the gantry 13 is rotated and the X-ray tube 15, X-ray detector 16 and cooling device 17 are operated.

[0035] Each detector 33 detects vibrations in the X-axis, Y-axis, and Z-axis directions, and a data logger 34 stores the detection data detected by each detector 33 in chronological order in synchronization with the rotation of the stand 13, and a communication unit 35 transmits the detection data stored in the data logger 34 to the external device unit 32.

[0036] The external device unit 32 acquires, via the communication unit 36, the detection data stored in the data logger 34, which is time-series detection data detected by the detector 33 in synchronization with the rotation of the stand 13, and displays the time-series progression of the acquired detection data in a graphical form on the monitor.

[0037] Fig. 5 shows an example of displaying the measurement results of the vibration measuring device 30 in a graphical form, in which the change in vibration value in each of the X-axis, Y-axis, and Z-axis directions is displayed in a three-dimensional graphic form. Fig. 5(a) shows a graphical display of the time series transition of detection data synchronized with the rotation of the gantry 13 in a first state in which the X-ray tube 15 is not irradiated, and Fig. 5(b) shows a graphical display of the time series transition of detection data synchronized with the rotation of the gantry 13 in a second state in which the X-ray tube 15 is irradiated. Figs. 5(a) and 5(b) show a three-dimensional graphic display in which the change in vibration value in each of the X-axis, Y-axis, and Z-axis directions is three-dimensionally plotted and displayed in a three-dimensional form, in a time series transition synchronized with the rotation of the gantry 13, based on the detection data of two detectors 33 arranged at two positions, the front (near side) and the rear (rear side) in the axial direction of the rotation shaft 14 of the gantry 13, at the position where the X-ray tube 15 of the gantry 13 is arranged. Acceleration [G] is shown along each of the X, Y, and Z axes.

[0038] It can be seen from Fig. 5 that the vibration value increases in the second state shown in Fig. 5(b) in which the X-ray tube 15 is irradiated, compared to the first state shown in Fig. 5(a) in which the X-ray tube 15 is not irradiated. Furthermore, it can be seen that the change in the vibration value on the front side is larger than the change in the vibration value on the rear side.

[0039] Fig. 6 is a waveform diagram of the measurement results of the vibration measuring device 30. Fig. 6 shows detection data of two detectors 33 arranged at two positions, the front (near side) and the rear (far side) in the axial direction of the rotation shaft 14 of the gantry 13, where the X-ray tube 15 of the gantry 13 is arranged, and the timing of exposure of the X-ray tube 15.

[0040] From FIG. 6, it can be seen that the vibration values ​​on both the front and rear sides change so as to increase when the X-ray tube 15 is irradiated, and further, that the change in vibration value on the front side is greater than that on the rear side.

[0041] In addition, the vibration values ​​can also be confirmed in the same manner by displaying the detection data of each detector 33 arranged at other measurement points, such as the position near the X-ray transparent window 21 of the X-ray tube 15, the position of the X-ray detector 16, and the position of the cooling device 17, in a graphical form as shown in Figures 5 and 6.

[0042] In addition, in FIG. 5 and FIG. 6, when the vibration value exceeds a predetermined threshold value, a warning to that effect may be displayed.

[0043] By measuring vibrations using the vibration measuring device 30, it is possible to confirm the resonant frequency at each measurement point in a first state in which the X-ray tube 15 is not emitting and in a second state in which the X-ray tube 15 is emitting, the change in the resonant frequency over time, and the matching between the X-ray CT device 10 and the X-ray tube 15, the cooling device 17, etc.

[0044] For example, when X-ray tube 15 generates X-rays, 99% of the electrical energy supplied is converted into heat. If this heat causes the resonant frequency to change due to deformation of the materials of the anode target and rotor of X-ray tube 15 and changes in rigidity, and this changes the resonant frequency of other structures, a resonance phenomenon will occur, resulting in abnormal noise, fluctuations in the tube current due to the vibration of the cathode filament of X-ray tube 15, and damage over time. However, the occurrence of the resonance phenomenon can be confirmed by vibration measuring device 30.

[0045] This makes it possible to provide feedback to the design of the X-ray CT device 10, the X-ray tube 15, the cooling device 17, etc., thereby improving the quality of the X-ray CT device 10 and shortening the period required to evaluate the quality of the X-ray CT device 10.

[0046] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0047] 10. Computer tomography equipment 11. Cabinet 13 Mounting stand 14 Rotational Axis 15 X-ray tube 17 Cooling device 30 Vibration measuring device 33 Detector 35 Communications Department 37 Acquisition Department 38 Display processing section

Claims

1. 1. A vibration measuring device for an X-ray computed tomography diagnostic apparatus comprising a housing, a gantry that rotates within the housing, and an X-ray tube mounted on the gantry, a detector disposed on at least one of the gantry and the X-ray tube, and detecting vibrations while the gantry is rotating; 2. A vibration measuring device for an X-ray computed tomography diagnostic apparatus comprising:

2. the X-ray computed tomography diagnostic apparatus is mounted on the gantry and includes a cooling device that cools the X-ray tube; The detector is disposed on at least one of the gantry, the X-ray tube, and the cooling device.

2. The vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 1.

3. The detectors are disposed at least at a position where the X-ray tube is disposed on the gantry and at two positions, one before the other and one after the other in the direction of the rotation axis of the gantry.

2. The vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 1.

4. The detector detects vibrations in a state in which the gantry rotates and the X-ray tube and the cooling device are not operating, and in a state in which the gantry rotates and the X-ray tube and the cooling device are operating.

2. The vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 1.

5. A communication unit is mounted on the platform and transmits detection data detected by the detector to an external device via wireless communication.

2. The vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 1.

6. an acquisition unit that acquires detection data detected by the detector in synchronization with the rotation of the gantry; 6. A vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 1.

7. A display processing unit is provided for displaying a graphic representation of the time series transition of the detection data acquired by the acquisition unit.

7. The vibration measuring device for an X-ray computed tomography diagnostic apparatus according to claim 6.

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