JP2010119753A - X-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve efficiency of power transmission between a rack fixing part and a rotation part, with respect to an X-ray CT apparatus provided with a power transmission part for transmitting power by noncontact through the use of electromagnetic induction. <P>SOLUTION: The X-ray CT apparatus includes: the rack fixing part; the rotation part which is freely rotatably supported on the rack fixing part; and the power transmission part for transmitting power between the rack fixing part and the rotation part, and having a fixing side winding wire wound around the rack fixing part, a fixing side iron core arranged close to the fixing side winding wire, a rotation side winding wire wound around the rotation part, and a rotation side iron core arranged close to the rotation side winding wire, wherein at least one of the fixing side iron core and the rotation side iron core covers a gap to be formed between the fixing side winding wire and the rotation side winding wire. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus that performs power transmission between a gantry fixing unit and a rotating unit in a non-contact manner, and particularly relates to an improvement in power transmission efficiency between the gantry fixing unit and the rotating unit.

  The X-ray CT apparatus is used for diagnosis by reconstructing and displaying the tomographic image of the subject based on X-ray projection data at various angles acquired by irradiating the subject with X-rays. It is. Many X-ray CT apparatuses include an X-ray tube that irradiates the subject with X-rays, an X-ray detector that is arranged opposite to the X-ray tube and acquires X-ray projection data, the X-ray tube, and the X-ray tube A line detector is mounted, and a rotating unit that rotates around the subject is provided. In order to drive the X-ray tube and the X-ray detector mounted on the rotating part, it is necessary to supply electric power to the rotating part from a gantry fixing part that rotatably supports the rotating part.

  In many X-ray CT apparatuses, a slip ring is used as a power transmission part between the gantry fixing part and the rotating part. The slip ring is composed of a metal ring and a metal brush brought into contact with the metal ring. For example, the slip ring has a structure in which a metal ring is provided on the gantry fixing part and a metal brush is provided on the rotating part. With such a structure, electric power can be transmitted between the gantry fixing portion and the rotating portion while rotating the rotating portion.

  However, in the slip ring, since the rotating part is rotated while the metal ring and the metal brush are in contact with each other, wear powder is generated due to wear of the metal ring and the metal brush, and maintenance work such as removal of the wear powder is required. . Therefore, Patent Document 1 discloses an X-ray CT apparatus including a power transmission unit that transmits power in a non-contact manner by using electromagnetic induction as a power transmission unit that replaces a slip ring.

  The power transmission unit disclosed in Patent Document 1 includes a fixed-side winding wound around a gantry fixing portion, a fixed-side iron core disposed in the vicinity of the fixed-side winding, and a rotation wound around a rotating portion. A side winding and a rotation side iron core disposed in the vicinity of the rotation side winding. When an alternating current flows through the fixed-side winding, an alternating magnetic flux φ is generated in the fixed-side iron core disposed in the vicinity of the fixed-side winding. The alternating magnetic flux φ generated in the fixed side iron core passes through the rotating side iron core, causes electromagnetic induction, and induces a voltage in the rotating side winding interlinked with the alternating magnetic flux φ. As a result, AC power is supplied to a high voltage transformer or the like connected to the rotation side winding.

Japanese Unexamined Patent Publication No. 7-204192

  By the way, in order to rotate the rotating part with respect to the gantry fixing part, it is necessary to provide a gap between the gantry fixing part and the rotating part. The gap becomes a place where the alternating magnetic flux φ leaks, and causes a reduction in power transmission efficiency of the power transmission unit. In particular, in order to increase the rotation speed of the rotating part in order to meet the demand for shortening the CT imaging time, the gap is made larger. Further, when the diameter of the opening provided in the rotating part is increased in order for the subject to pass, the gap is further increased. If the gap between the gantry fixing portion and the rotating portion is increased, the leakage of the alternating magnetic flux φ is increased, and the power transmission efficiency is further decreased.

  An object of the present invention is to improve the efficiency of power transmission between a gantry fixing unit and a rotating unit in an X-ray CT apparatus including a power transmission unit that transmits electric power in a non-contact manner by using electromagnetic induction. .

  To achieve the above object, the present invention provides a gantry fixing portion, a rotating portion that is rotatably supported with respect to the gantry fixing portion, and an electric power that transmits electric power between the gantry fixing portion and the rotating portion. A transmission portion, a fixed-side winding wound around the gantry fixing portion, a fixed-side iron core disposed in the vicinity of the fixed-side winding, and a rotation-side winding wound around the rotating portion; An X-ray CT apparatus comprising: a rotation-side iron core disposed in the vicinity of the rotation-side winding; wherein at least one of the fixed-side iron core and the rotation-side iron core is the fixed side It is characterized by having a structure covering a gap formed between the winding and the rotation side winding.

  According to the present invention, in the X-ray CT apparatus provided with a power transmission unit that transmits power in a non-contact manner by using electromagnetic induction, the efficiency of power transmission between the gantry fixing unit and the rotation unit can be improved. . The power transmission efficiency can reduce the size of the power supply device included in the X-ray CT apparatus, and can contribute to a reduction in running cost.

  An X-ray CT apparatus to which the present invention is applied will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an overall configuration block diagram of a first embodiment of an X-ray CT apparatus to which the present invention is applied. The X-ray CT system irradiates the subject 105 with X-rays from various angles, measures the distribution of the X-ray dose transmitted through the subject 105, and displays the tomographic image of the subject 105 reconstructed based on the measurement results To do. The X-ray CT apparatus according to the present embodiment is divided into a fixed side and a rotating side. The fixed side includes a gantry fixing unit 100 and a console 300, and the rotating side includes a rotating unit 200. Yes. The rotating part 200 is supported rotatably with respect to the gantry fixing part 100.

  The gantry fixing unit 100 includes a power supply 30 and an inverter 34. The rotating unit 200 includes a high voltage transformer 37, a high voltage rectifier 38, an X-ray tube 39, and an X-ray detector 40. Between the gantry fixing unit 100 and the rotating unit 200, a power transmission unit 102 and non-contact signal transmission means 108 for transmitting electric power from the gantry fixing unit 100 to the rotating unit 200 are interposed. The console 300 includes an image processing device 46 and an image display device 47.

  The power source 30 generates a DC voltage, and includes a commercial AC power source 31, a converter 32 that converts the voltage of the AC power source 31 into a desired DC voltage, and a smoothing capacitor 33 that smoothes the output voltage of the converter 32. ing. The inverter 34 converts the DC voltage output from the power supply 30 into a high-frequency AC voltage. The output of the inverter 34 is transmitted to the rotating unit 200 by the power transmission unit 102 and input to the high voltage transformer 37. The high voltage transformer 37 boosts the input AC voltage. The high voltage rectifier 38 rectifies the output voltage of the high voltage transformer 37 and converts it into a direct high voltage.

  The X-ray tube 39 irradiates the subject 105 with X-rays when supplied with the DC voltage output from the high voltage rectifier 38. X-rays that have passed through the subject 105 enter the X-ray detection unit 40. The X-ray detection unit 40 detects X-rays transmitted through the subject 105 and amplifies the detected signal. The X-ray detection unit 40 is disposed opposite to the X-ray tube 39 and detects a dose distribution of transmitted X-rays. 42 and a preamplifier 43 for amplifying a detection signal from the detector 42. By irradiating and detecting X-rays while the X-ray tube 39 and the X-ray detection unit 40 provided in the rotating unit 200 rotate, transmission X-ray dose distributions at various angles can be measured.

  The non-contact signal transmission means 108 transmits the detection signal of the X-ray detection unit 40 from the rotation unit 200 to the gantry fixing unit 100, and includes a rotation side transmission device 107 and a fixed side reception device 106. The detection signal received by the fixed-side receiving device 106 is transmitted to the image processing device 46. The image processing device 46 generates a tomographic image of the subject 105 by reconstructing the transmitted detection signal. The image display device 47 displays the tomographic image generated by the image processing device 46, and is, for example, a television monitor.

  The power transmission unit 102 includes a fixed side winding 2 wound around the gantry fixing unit 100 and a rotation side winding 4 wound around the rotating unit 200. The fixed winding 2 is connected to the inverter 34, and the rotating winding 4 is connected to the high voltage transformer 37. The rotation side winding 4 is disposed in the vicinity of the fixed side winding 2. With this arrangement, when an alternating current flows through the fixed-side winding 2, an alternating magnetic flux φ is generated around the fixed-side winding, and the rotating-side winding 4 interlinking with the alternating magnetic flux φ is subjected to electromagnetic induction. A voltage is induced and power is transmitted. A detailed configuration of the power transmission unit 102 will be described later with reference to FIG.

  FIG. 2 (a) is a view of the power transmission unit 102 viewed from the direction of the rotation axis of the rotation unit 200, and FIG. 2 (b) is a view of the AA cross section of FIG. 2 (a) viewed from the direction of the arrow. The rotating part 200 rotates in the direction of the arc of the arrow in FIG. The power transmission unit 102 of the present embodiment includes a fixed side iron core 1 and a rotary side iron core 3 in addition to the fixed side winding 2 and the rotation side winding 4 described above.

  The fixed side winding 2 and the rotation side winding 4 are wound around the gantry fixing unit 100 and the rotation unit 200 in the rotation direction of the rotation unit 200, respectively. A gap 5 is formed between the fixed-side winding 2 and the rotating-side winding 4 so that the rotating unit 200 can smoothly rotate with respect to the gantry fixing unit 100.

  The fixed side iron core 1 and the rotation side iron core 3 are arranged in the vicinity of the fixed side winding 2 and the rotation side winding 4 along the rotation direction of the rotary unit 200, respectively. This arrangement reduces the leakage of the alternating magnetic flux φ generated around the fixed-side winding 2 to the outside of the fixed-side iron core 1 and the rotating-side iron core 3, and improves the efficiency of power transmission by electromagnetic induction. it can. The fixed-side iron core 1 and the rotary-side iron core 3 of the present embodiment have a structure divided in the rotation direction of the rotation unit 200 in order to facilitate the manufacture of the power transmission unit 102, but are connected in the rotation direction. The structure may be different. A gap 6 is arranged between the fixed iron core 1 and the rotating iron core 3 so that the rotating part 200 can smoothly rotate with respect to the gantry fixing part 100. As materials used for the fixed side iron core 1 and the rotary side iron core 3, ferrite, silicon steel plate, permalloy, other ferromagnetic materials or paramagnetic materials are suitable.

The fixed-side iron core 1 of the present embodiment is characterized by a cross-sectional shape, and has a cross-sectional shape in which the fixed-side iron core 1 covers a gap 5 formed between the fixed-side winding 2 and the rotation-side winding 4. . The inventors confirmed by simulation that the coupling ratio between the fixed side and the rotating side is improved, that is, the power transmission efficiency between the gantry fixing part and the rotating part is improved by adopting such a cross-sectional shape. .
Fig. 3 shows the simulation results for the coupling rate. In FIG. 3, the vertical axis represents the coupling ratio between the fixed side and the rotation side, the horizontal axis represents the gap 5 and the gap 6, and the iron core having the cross-sectional shape shown in FIG.

  The comparative example shown in FIG. 4 includes the fixed-side winding 2, the rotating-side winding 4, the fixed-side iron core 1, and the rotating-side iron core 3, as in the present embodiment, and the fixed-side winding 2 and the rotating side. A gap 5 is formed between the side windings 4, and a gap 6 is formed between the fixed side iron core 1 and the rotation side iron core 3. The cross-sectional shape of the comparative example is the cross-sectional shape shown in Patent Document 1. The difference from the present embodiment is the cross-sectional shape of the fixed-side iron core 1 and the rotary-side iron core 3, and both the fixed-side iron core 1 and the rotary-side iron core 3 have a cross-sectional shape that does not cover the gap 5.

  In the simulation results of FIG. 3, when the gap 5 and the gap 6 are 1 mm, the coupling rate of this embodiment shows 0.968, and the comparative example shows 0.967, respectively, and when the gap 5 and the gap 6 are 5 mm, this embodiment Shows 0.968, and the comparative example shows 0.967. That is, in the simulated range, this embodiment shows a higher coupling rate than the comparative example, and the difference between the gap 5 and the gap 6 increases as the gap 5 and the gap 6 increase. From this result, the gap 5 formed between the fixed side winding 2 and the rotation side winding 4 has a cross-sectional shape covered with the fixed side iron core 1, so that the power between the gantry fixing part and the rotation part is It can be seen that the transmission efficiency can be improved.

  FIG. 5 shows the result of calculating the input power required on the fixed side in order to output 150 kW on the rotating side based on the simulation result of FIG. It turns out that this embodiment can reduce input electric power compared with a comparative example. This result shows that the X-ray CT apparatus of the present embodiment can reduce the running cost as compared with the comparative example, and the power supply 30 can be downsized.

  In the simulation, the leakage flux was also compared. As a result, it was found that when the gap 5 and the gap 6 are 5 mm, this embodiment can reduce the leakage magnetic flux by about 20% compared to the comparative example. This result shows that the X-ray CT apparatus of this embodiment is advantageous in terms of electromagnetic compatibility (EMC).

  In the present embodiment, the cross-sectional shape in which the fixed-side iron core 1 covers the gap 5 has been described, but it goes without saying that the same effect can be obtained even if the rotary-side iron core 3 has a cross-sectional shape that covers the gap 5. . However, the cross-sectional shape in which the fixed iron core 1 covers the gap 5 can reduce the volume of the rotating part 200 because the volume of the rotary iron core 3 can be reduced compared to the cross-sectional shape in which the rotary iron core 3 covers the gap 5. A new effect can be obtained.

(Second embodiment)
FIG. 6 shows a cross-sectional shape of the second embodiment. The difference between this embodiment and the first embodiment shown in FIG. 2 (b) is that the fixed-side iron core 1 has a cross-sectional shape that covers not only the gap 5 but also the side of the rotation-side iron core 3. It is. By setting it as such a cross-sectional shape, compared with 1st embodiment, the efficiency of electric power transmission can be improved and the fixed part can be reduced in weight.

(Third embodiment)
FIG. 7 shows a cross-sectional shape of the third embodiment. The difference from the first embodiment and the second embodiment is that the rotation-side iron core 3 has a concave cross section that covers the side of the rotation-side winding 4. By adopting such a cross-sectional shape, in the step of winding the rotation side winding 4 around the rotation unit 200, the rotation side winding 4 can be arranged in the concave shape of the rotation side iron core 3, so that the power transmission unit 102 Manufacture can be facilitated.

(Fourth embodiment)
FIG. 8 shows a cross-sectional shape of the fourth embodiment. The difference from the first embodiment to the third embodiment is that the cross-sectional shapes of the fixed-side iron core 1 and the rotary-side iron core 3 are substantially the same. The gap 5 is formed in a cross-section so as to cover not only one iron core but also both iron cores. By adopting such a cross-sectional shape, it becomes possible to share the parts of the fixed side iron core 1 and the rotary side iron core 3, so that the manufacturing cost of the power transmission unit 102 can be reduced.

(Fifth embodiment)
In the X-ray CT apparatus described in the first embodiment, transmission of power is one system. However, depending on the apparatus, power of multiple systems may be transmitted. In the present embodiment, power is transmitted through two systems.

  FIG. 9 is a block diagram of the overall configuration of the X-ray CT apparatus of the present embodiment. The difference from the first embodiment is that power transmission to the stator coil 62 for rotating the rotary anode included in the X-ray tube 39 and the heating transformer 61 for heating the cathode included in the X-ray tube 39 is performed. In order to do so, the power transmission unit 102 includes a power transmission unit 112 of a different system. The power system includes a power source 50, an inverter 54, a ring-shaped transformer 112, rectifiers 55 and 56, smoothing capacitors 57 and 58, inverters 59 and 60, a heating transformer 61, and a stator coil 62.

  The power source 50 and the inverter 54 have the same configuration as the power source 30 and the inverter 34, although the output power is different from that of the power source 30 and the inverter 34. The rectifiers 55 and 56 are devices that convert an AC voltage input via the power transmission unit 112 into a DC voltage. The smoothing capacitors 57 and 58 are for smoothing the ripple of the output voltage from the rectifiers 55 and 56 so as to approach the DC voltage. The inverters 59 and 60 convert the output voltage from the smoothing capacitors 57 and 58 into a high-frequency AC voltage and output it to the stator coil 62 and the heating transformer 61, respectively.

  The power transmission unit 102 has the same configuration as that of the first embodiment. The power transmission unit 112 includes a fixed side winding 111 wound around the gantry fixing unit 100 and a rotation side winding 113 wound around the rotation unit 200. The fixed winding 111 is connected to the inverter 54, and the rotating winding 113 is connected to the rectifiers 55 and 56. The rotation side winding 113 is arranged in the vicinity of the fixed side winding 111. The detailed configuration of the power transmission unit 112 will be described later together with the power transmission unit 102 with reference to FIG.

  FIG. 10 (a) is a view of the power transmission unit 102 and the power transmission unit 112 seen from the direction of the rotation axis of the rotary unit 200, and FIG. 10 (b) is a view of the CC cross section of FIG. It is a figure. The rotating unit 200 rotates in the direction of the arc of the arrow in FIG. The power transmission unit 112 of this embodiment includes a fixed side iron core 7 in addition to the fixed side winding 111 and the rotation side winding 113 described above, and shares the rotation side iron core 3 with the power transmission unit 102. As long as the alternating magnetic flux φ1 generated around the fixed-side winding 2 and the alternating magnetic flux φ2 generated around the fixed-side winding 111 do not interfere with each other, the iron core can be shared. By sharing the iron core between the two power systems, the man-hours for assembling the power transmission unit 102 and the power transmission unit 112 can be reduced.

  The cross-sectional shapes of the fixed side iron core 1 and the fixed side iron core 7 of the present embodiment are similar to the first embodiment in the gap formed between the fixed side winding 2 and the rotation side winding 4 and the fixed side winding. It has a shape that covers a gap formed between the wire 111 and the rotation-side winding 113. By adopting such a cross-sectional shape, the coupling rate between the fixed side and the rotating side is improved, that is, the power transmission efficiency between the gantry fixing part and the rotating part is improved as in the first embodiment. is there.

(Sixth embodiment)
FIG. 11 shows a cross-sectional shape of the sixth embodiment. Similar to the fifth embodiment, this embodiment also includes two power systems. This embodiment is different from the fifth embodiment in that the rotation-side iron core 3 has a concave cross section that covers the sides of the rotation-side winding 4 and the rotation-side winding 113. With such a cross-sectional shape, in the step of winding the rotating side winding 4 and the rotating side winding 113 around the rotating unit 200, the rotating side winding 4 and the rotating side winding are included in the concave shape of the rotating side iron core 3. Since the wire 113 can be disposed, the power transmission unit 102 can be easily manufactured.

(Seventh embodiment)
FIG. 12 shows a cross-sectional shape of the seventh embodiment. As in the fifth and sixth embodiments, this embodiment also includes two power systems. This embodiment is different from the fifth and sixth embodiments in that a rotating side iron core is provided for each power system. That is, the rotation-side iron core 3 is disposed in the vicinity of the rotation-side winding 4, and the rotation-side iron core 8 is disposed in the vicinity of the rotation-side winding 113. By adopting such a configuration, the interference between the alternating magnetic flux φ1 generated by the alternating current flowing in the fixed side winding 2 and the alternating magnetic flux φ2 generated by the alternating current flowing in the fixed side winding 111 is reduced. be able to.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these. In the fifth to seventh embodiments, the X-ray CT apparatus having two power systems has been described. However, the present invention can be applied even to an X-ray CT apparatus having three or more power systems. Is possible. In all the embodiments, the case where power is transmitted from the stationary side to the rotating side has been described. However, the present invention can also be applied to the case where power is transmitted from the rotating side to the stationary side.

Block diagram of an X-ray CT apparatus to which the first embodiment of the present invention is applied The figure explaining the electric power transmission part of 1st embodiment of this invention The figure explaining the effect of 1st embodiment of this invention The figure explaining the comparative example with respect to 1st embodiment of this invention The figure explaining the other effect of 1st embodiment of this invention The figure explaining the electric power transmission part of 2nd embodiment of this invention The figure explaining the electric power transmission part of 3rd embodiment of this invention The figure explaining the electric power transmission part of 4th embodiment of this invention Block diagram of an X-ray CT apparatus to which the fifth embodiment of the present invention is applied The figure explaining the electric power transmission part of 5th embodiment of this invention The figure explaining the electric power transmission part of 6th embodiment of this invention The figure explaining the electric power transmission part of 7th embodiment of this invention

Explanation of symbols

  1, 7 Fixed iron core, 2, 111 Fixed coil, 3, 8 Rotating iron core, 4, 113 Rotating coil, 5 Clearance between fixed coil and rotating coil, 6 Fixed iron core and rotating coil Core gap, 30, 50 power supply, 31, 51 Commercial power supply, 32, 52 converter, 33, 53, 57, 58 Smoothing capacitor, 34, 54, 59, 60 Inverter, 37 High voltage transformer, 38 High voltage rectifier circuit , 39 X-ray tube, 40 X-ray detector, 42 detector, 43 preamplifier, 46 Image processing device, 47 Image display device, 55, 56 Rectifier circuit, 61 Heating transformer, 62 Stator coil, 100 Mounting bracket, 105 Subject, 106 Fixed-side receiving device, 107 Rotating-side receiving device, 108 Non-contact signal transmission means, 200 Rotating unit, 300 Console

Claims (7)

A gantry fixing part, a rotating part supported rotatably with respect to the gantry fixing part, and a power transmission part for transmitting electric power between the gantry fixing part and the rotating part, The fixed side winding wound around, the fixed side iron core arranged near the fixed side winding, the rotation side winding wound around the rotating part, and arranged near the rotation side winding. An X-ray CT apparatus comprising: a rotating iron core;
An X-ray CT apparatus characterized in that at least one of the fixed-side iron core and the rotating-side iron core covers a gap formed between the fixed-side winding and the rotating-side winding. The X-ray CT apparatus according to claim 1,
An X-ray CT apparatus having a structure in which the fixed iron core covers the gap. The X-ray CT apparatus according to claim 2,
An X-ray CT apparatus having a structure in which the stationary iron core covers the rotating iron core. The X-ray CT apparatus according to claim 2 or 3,
An X-ray CT apparatus having a structure in which the rotation-side iron core covers the rotation-side winding. The X-ray CT apparatus according to claim 1,
An X-ray CT apparatus having a structure in which the rotation-side iron core covers the rotation-side winding and the fixed-side iron core covers the fixed-side winding. The X-ray CT apparatus according to claim 1,
An X-ray CT apparatus having a structure in which at least one of the fixed side iron core and the rotation side iron core is divided in the rotation direction of the rotating part. The X-ray CT apparatus according to claim 1,
An X-ray CT apparatus comprising a plurality of the power transmission units.

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