JP5758126B2 - X-ray CT system - Google Patents

Description

  The present invention relates to an X-ray CT apparatus, and more particularly, to an X-ray CT apparatus that transmits and receives signals from a stationary part and a rotating part using an optical signal.

  Recent X-ray CT systems use a slip ring method, that is, a scanner that exchanges signals between the rotating part and the stationary part by mechanical sliding contact between the ring and the brush in order to enable continuous rotation measurement. It is common. Signals to be exchanged include measurement signals and control signals.

  A measurement signal is a signal detected from an X-ray detector corresponding to an X-ray that has passed through a subject in a measurement means that is mounted on a rotating part and that is composed of an X-ray source and a multi-channel X-ray detector facing each other. That is. This measurement signal is transmitted from the rotating part to the stationary part.

  Control signals include a measurement trigger signal for starting the acquisition of the measurement signal, an X-ray feedback signal for feedback control of the X-ray output, etc. The measurement trigger signal is sent from the stationary part to the rotating part, and the X-ray feedback. The signal is transmitted from the rotating part to the stationary part.

  In an X-ray CT system that transmits these signals using the slip ring method, data failure or data change may occur due to contact failure due to contact wear of the slip ring brush, etc., metal scrap cleaning, or brush replacement It requires a lot of maintenance man-hours. Furthermore, when the measurement rate is increased or when it is desired to increase various control signals, the number of slip ring channels must be added, and the size, weight, and cost of the scanner are inevitably increased.

  In order to cope with such a problem, an X-ray CT apparatus in which the slip ring method is replaced with an optical transmission method has been proposed.

  For example, Patent Document 1 discloses a structure in which a light emitting element is arranged on the circumference of a rotating unit, and a receiving unit arranged in a stationary unit can receive data regardless of the rotation angle.

  In Patent Document 2, line-shaped light emitters are arranged in a ring shape. This light emitter is, for example, a transparent plastic columnar body that emits light on its side surface, and has a structure in which data can be received by a light receiving unit located at a remote position.

  In addition to the non-contact signal transmission method as described above, Patent Document 3 discloses a non-contact power transmission method.

Japanese Unexamined Patent Publication No. 2000-82998 Japanese Patent Laid-Open No. 10-208185 Japanese Patent No. 4008010

  In the conventional examples of the non-contact signal transmission technologies such as Patent Document 1 and Patent Document 2 listed above, signals can be transmitted and received without contact regardless of the rotation angle of the rotating unit. There are the following problems.

  First, Patent Document 1 has a structure in which a light source is arranged on the circumference.For example, assuming that the scanner opening diameter is 800 mm, and the diameter of the mechanism unit in which the light source is arranged is 1 m, Consider the required number of LEDs. If an 80 ° LED with wide directivity is used and the distance from the light source to the light receiving unit is 5 mm, 436 or more light sources are required, resulting in a large structure.

  Further, in Patent Document 2, since it is possible to arrange in a ring shape using a light emitting body that is provided with a transparent plastic columnar body so that side surfaces emit light, it is not necessary to arrange a large number of light sources. However, when the light emitters are arranged in a ring shape, if the light emitters are short in the longitudinal direction, a gap is formed at the joint, and a portion that does not emit light is formed. On the other hand, if the length is long, a portion where the light emitters cross is generated, and the light emitting portion and the light receiving portion are displaced from each other. Furthermore, since the light emitting body that emits light on the side surface has a loss along the line, the luminance is lower than that of an LED or the like, and the luminance decreases as the distance from the light source increases. Therefore, in addition to the need to make the distance between the light emitting unit and the light receiving unit sufficiently close, and considering the mechanical accuracy due to rotational shake, the problem that the light emitter is short and long in the longitudinal direction is the transmission / reception data as described above. It cannot be ignored in terms of reliability.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an X-ray CT apparatus that improves the reliability of optical transmission.

  In order to solve the above-described problems, the X-ray CT apparatus according to the present invention is characterized by improving the luminance of light received by the light receiving unit using an optical film.

  More specifically, an X-ray CT apparatus according to the present invention detects an X-ray source that generates X-rays and the X-ray source that is disposed opposite to the X-ray source and transmits a subject and outputs a measurement signal. An X-ray detector, a rotary scanner equipped with the X-ray source and the X-ray detector, rotating the X-ray source and the X-ray detector around the subject, and a stationary supporting the rotary scanner And a signal transmission unit composed of a light emitter and a light receiving unit, and between the light emitter and the light receiving unit, for transmitting and receiving an optical signal between the rotary scanner and the stationary unit. And a diffusion sheet for diffusing the light emitted from the light emitter, and a prism sheet for condensing the light emitted from the light emitter toward the light receiving section.

  According to the present invention, the light emitted from the illuminant attenuates as the distance from the illuminant increases, and thus unevenness of light (brightness) occurs. However, the unevenness of the light can be reduced by using a diffusion sheet. . Further, by using the prism sheet, the scattered light can be condensed toward the light receiving unit, and the luminance can be improved. By providing these diffusion sheets and / or prism sheets between the light emitter and the light receiving section, it is possible to provide an X-ray CT apparatus that improves the reliability of the optical signal.

Schematic showing the overall configuration of the X-ray CT apparatus 100 to which the invention is applied Partial enlarged view of the X-ray CT apparatus according to the first embodiment Partial enlarged view in which a partial region (region surrounded by a dotted line) in the A-A ′ cross section of FIG. 2 is enlarged. Partial enlarged view of the X-ray CT apparatus according to the second embodiment Partial enlarged view of the X-ray CT apparatus according to the third embodiment Schematic diagram showing the configuration of the light receiving unit Partial enlarged view of the X-ray CT apparatus according to the fourth embodiment Partial enlarged view of the X-ray CT apparatus according to the fifth embodiment Partial enlarged view of the X-ray CT apparatus according to the sixth embodiment Partial enlarged view of the X-ray CT apparatus according to the seventh embodiment

  Embodiments of an X-ray CT apparatus according to the present invention will be described below with reference to the accompanying drawings.

<Outline configuration>
FIG. 1 is a schematic diagram showing the overall configuration of an X-ray CT apparatus 100 to which the present invention is applied. The X-ray CT apparatus 100 includes a stationary unit (also referred to as a scan gantry) 110 that accommodates a subject, and an image reconstruction unit 120. The stationary unit 110 has a rotary scanner 111 having an opening 114 into which a subject is carried, an X-ray tube 112 mounted on the rotary scanner 111, and an X-ray tube 112 attached to the X-ray bundle. A collimator 113 to be controlled, an X-ray detector 115 mounted on the rotary scanner 111 facing the X-ray tube 112, and a detector circuit for converting X-rays detected by the X-ray detector 115 into predetermined measurement signals 116 and a scan control circuit 117 for controlling the rotation of the rotary scanner 111 and the width of the X-ray bundle.

  The image reconstruction unit 120 includes an input device 121 for inputting a subject's name, examination date and time, examination conditions, and the like, and an image computation circuit that performs CT image reconstruction by computing the measurement signal S1 sent from the detector circuit 116 122, an image information adding unit 123 for adding information such as a subject's name, examination date and time, examination conditions inputted from the input device 121 to the CT image created by the image arithmetic circuit 122, and image information added And a display circuit 124 for adjusting the display gain of the CT measurement signal S2 and outputting it to the display monitor 130.

  In the X-ray CT apparatus 100, X-rays are irradiated from the X-ray tube 112 in a state where the subject is placed on a bed (not shown) installed in the opening 114 of the stationary part 110. The X-ray is obtained by the collimator 113 and is detected by the X-ray detector 115. At this time, by rotating the rotary scanner 111 around the subject, the X-ray transmitted through the subject is detected while changing the X-ray irradiation direction. A tomographic image created by the image reconstruction unit 120 based on this measurement signal is displayed on the display monitor 130.

  In the X-ray CT apparatus 100, measurement signals and various control signals transmitted and received between the rotary scanner 111 and the stationary unit 110 are transmitted by transmitting and receiving optical signals.

<First Embodiment>
Hereinafter, the first embodiment will be described with reference to FIGS. FIG. 2 is a partially enlarged view of the X-ray CT apparatus according to the first embodiment, in which the stationary part 110 and the rotary scanner 111 are enlarged. FIG. 3 is an enlarged schematic view of a partial region (region surrounded by a dotted line) in the AA ′ cross section of FIG. 2, and is a schematic diagram for explaining a fixing structure of the diffusion sheet 16 and the prism sheet 17. is there.

  In FIG. 1, the rotary scanner 111 is positioned inside the stationary part 110, whereas in FIG. 2, the rotational radius of the rotary scanner 111 is drawn larger than the rotational radius of the stationary part 110, and the rotary scanner 111 is located outside. The stationary part 110 is located inside. This is because the rough positional relationship between the stationary unit 110 and the rotary scanner 111 is as shown in FIG. 1, but the details are, for example, stationary as in the signal transmission unit 3b in FIG. 8 of the fifth embodiment to be described later. This is because the portion 110 is located inside the rotary scanner 111, and there is no problem in the alignment of the positional relationship between the stationary portion 110 and the rotary scanner 111 in each figure.

  As shown in FIG. 2, the stationary unit 110 is arranged along the circumferential direction of the rotary scanner 111 so that the light emitter 11 emits light evenly on the circumference of the stationary unit 110 in the outer diameter direction. On the other hand, the light receiving unit 28 is disposed in the rotary scanner 111. A reflection sheet 15 is attached over the entire circumference between the light emitter 11 and the stationary part 110, that is, in a direction other than the light emission direction of the light emitter 11. In addition, in the light emitting direction of the light emitter 11, a diffusion sheet 16 is attached so as to cover all the light emitters 11 arranged in the circumferential direction, and further the prism sheet 17 is placed on the diffusion sheet 16 (to the light receiving unit 28). It is attached to the opposite surface.

  Next, a method for fixing each sheet will be described with reference to FIG.

  FIG. 3 (a) shows an example in which a double-sided tape (or adhesive) is used in two layers. The diffusion sheet 16 is fixed to the stationary part 110 using a double-sided tape (or adhesive) 30 between the stationary part 110 and the diffusion sheet 16. Further, a double-sided tape (or adhesive) 31 is used between the diffusion sheet 16 and the prism sheet 17, and the prism sheet 17 is bonded to the diffusion sheet 16. Thereby, the diffusion sheet 16 and the prism sheet 17 are fixed.

  FIG. 3 (b) shows an example in which a double-sided tape (or adhesive) is used in one layer. The end portion of the diffusion sheet 16 is fixed to the stationary portion 110 with the double-sided tape 32, and the prism sheet 17 is fixed thereon. Compared to FIG. 3 (a), the width of the diffusion sheet 16 can be slightly reduced, and the amount of double-sided tape used can be halved.

  FIG. 3 (c) shows an example in which a single-sided tape is used for the outermost layer. The diffusion sheet 16 and the prism sheet 17 are placed on the stationary part 110, and the ends thereof are fixed with the single-sided tape 33. Compared to FIG. 3 (b), the width of the prism sheet can be made slightly smaller, and the use of the single-sided tape 33 instead of the double-sided tape 32 makes the fixing operation simpler.

  FIG. 3 (d) is a drawing obtained by extending the cross-sectional view of FIG. 3 (c) in the circumferential direction. The single-sided tape 33 may be processed by winding it continuously around the circumference, or as shown in Fig. 3 (d), it may be dispersed in various places in the circumferential direction and fixed with tape pieces. Good.

  In the above description, the fixing structure of the diffusion sheet 16 and the prism sheet 17 has been described using a double-sided tape, an adhesive, and a single-sided tape. However, it may be attached using a mechanical attachment structure such as screwing. In this case, when it becomes necessary to replace the diffusion sheet 16 and the prism sheet 17, the replacement is easier than the adhesive fixing.

  Next, optical transmission between the stationary unit 110 and the rotary scanner 111 will be described. When a signal is transmitted from the stationary unit 110 to the rotary scanner 111, the light receiving unit 28 receives light by turning on and off the light emission of the light emitter 11.

  In the light emitter 11 such as an LED, not all light is emitted in the direction intended by the light emitter 11, but scattered light is generated, and the light is also scattered behind the light emitter 11. The reflection sheet 15 is a polyester film material having a function of reflecting light, and is provided so as to improve the luminous efficiency by reflecting such scattered light and emitting light in an intended direction.

  The diffusion sheet 16 is a material having a light diffusion function in which fine particles such as titanium dioxide and calcium carbonate are contained in a resin such as translucent acrylic or polycarbonate, and can reduce light unevenness. Although it depends on the diffusion capability of the diffusion sheet 16, even if the number of the light emitters 11 is reduced and they are spaced apart from each other, the light is scattered, so that uniform light emission can be obtained.

  The prism sheet 17 is made of polycarbonate and is a material having a function of collecting light in each direction and increasing luminance in a direction perpendicular to the light emitting surface. In other words, the luminance can be compensated when the diffusion sheet 16 diffuses the light and the luminance decreases to reach the sensitivity of the light receiving unit.

  As these diffusion sheet 16 and prism sheet 17, as shown in FIG. 2, a material that is cut into a strip shape that covers the circumference and has a narrow lateral width is used. By doing so, even when the X-ray CT apparatus 100 rotates at a high speed of 0.3 rot / s, it is easy to make a structure resistant to distortion and vibration due to centrifugal force.

  The light receiving unit 28 includes a plurality of light receiving elements, and the error rate can be reduced by combining the outputs of the light receiving elements into one received signal.

  As described above, the light of the light emitter 11 is diffused by the diffusion sheet 16. For example, when the distance between the reflection sheet 15 and the diffusion sheet 16 is 20 mm, the distance between the light emitters 11 is 20 mm. Thus, it is confirmed that uniform light is emitted. Therefore, assuming that the diameter of the mechanism portion in which the light emitter is disposed is 1 m, it is sufficient that the number of the light emitters 11 is at least 157, and the light emitters can be configured with a number equal to or less than 1/2 of the conventional example. .

<Second Embodiment>
Next, a second embodiment will be described based on FIG. FIG. 4 is a schematic diagram of the second embodiment, which basically has the same structure and operation as the first embodiment, but the arrangement positions of the diffusion sheet 26 and the prism sheet 27 are different. The diffusion sheet 26 and the prism sheet 27 are arranged in the stationary part 110 in the first embodiment, whereas in the second embodiment, the diffusion sheet 26 and the prism sheet 27 are arranged in the rotary scanner 111 and attached so as to cover the light receiving surface of the light receiving part 28. ing. In this case, the areas of the diffusion sheet 26 and the prism sheet 27 that cover the light receiving surface of the light receiving unit 28 need to be larger in the circumferential direction than the effective light receiving area of the light receiving unit 28 in order to benefit from the functions of these sheets. . For example, it is as wide as the arrangement pitch of the respective light emitters 11. By doing so, not only the light of the light emitting unit 11 facing the light receiving unit 28 but also the light in which the light of the adjacent light emitting unit 11 is diffused can be added to increase the light receiving sensitivity.

  Needless to say, the route from which the light emitted from the light emitter 11 reaches the light emitter 11 → the diffusion sheet 26 → the prism sheet 27 → the light receiving unit 28 is the same as in the first embodiment, and the operation is the same. Further, the reflection sheet 15 is attached around the light emitter 11 as in the first embodiment.

  Compared to the first embodiment, the area that requires the diffusion sheet 26 and the prism sheet 27 may be small. However, since the light-emitting body 11 has a bare structure, a protective film that sufficiently transmits light may be attached.

<Third embodiment>
Next, a third embodiment will be described based on FIG. 5 and FIG. FIG. 5 is a partially enlarged view of the X-ray CT apparatus according to the third embodiment. FIG. 6 is a schematic diagram showing the configuration of the light receiving unit. The third embodiment has basically the same structure and operation as the first embodiment, but the mode of the light emitter 12 is different. In the first embodiment, a point light-emitting type light emitter such as an LED is used, whereas in the third embodiment, a line-shaped light emitter 12 whose surface emits light uniformly is used. The light emitter 12 may emit light by surface-treating the side surface of a transparent resin material such as a side-emitting optical fiber or a columnar and long acrylic.

  It goes without saying that the light emitted from the light emitter 12 reaches the light emitter 12 → the diffusion sheet 16 → the prism sheet 17 → the light receiving unit 28, and the operation is the same as in the first embodiment. . Further, the reflection sheet 15 is attached around the light emitter 12 as in the first embodiment, and is configured such that light emitted from the light emitter 12 reaches the light receiver 28 efficiently.

  In the third embodiment, since the optical fiber is used as the line-shaped light emitter that emits light along the longitudinal direction, the light emitter 12 has an end portion as shown in FIG. For example, there are one or a plurality of light sources 121 a and 121 b such as LEDs, and light is incident on the light emitter 12. In FIG. 6, the light sources 121a and 121b are located in the gaps at the end portions in the longitudinal direction of the light emitter 12. However, if the gaps at the end portions of the light emitters 12 are large, the light sources 121a and 121b transmit light onto the diffusion sheet 16 and the prism sheet 17. There is no part. For this reason, in order to make the portion without light as small as possible, it is more preferable that the light sources 121a and 121b are arranged so that light enters from the other direction at the end of the light emitter 12.

  FIG. 6 is a schematic diagram showing a simple configuration of the light receiving unit 28. The light received by the photodiodes 81a and 81b is converted into an electric signal, the signal is amplified by the amplifiers 82a and 82b, and the logical sum 83 of these two signals is obtained.

  6, the light emitted from the light emitter 12 is received by the photodiode 81a in the light receiving unit 28 but cannot be received by the photodiode 81b. However, the presence of the logical sum 83 allows a signal to be transmitted if either photodiode can receive light. The greater the number of photodiodes, the more reliable the signal transmission.

  In the case of the present embodiment, by using the line-shaped light emitter 12, unevenness of light due to the light emitter 11 at points is unlikely to occur as in the first and second embodiments. However, light unevenness occurs in the gap between the end portions of the light emitters 12 as described above, but this is mitigated by the diffusion sheet 16 to improve the reliability of transmission data. Furthermore, when the light emitter 12 is formed of a general-purpose optical fiber, the general light emitter 12 has a circular cross section and a thin outer diameter of several millimeters. Due to the manufacturing accuracy of the support system and the shake caused by rotation, if the deviation shown in the arrow in the direction of the body axis occurs, unevenness of light occurs and the reliability of the transmission data is lost. Try to lose. In addition, the line-shaped light emitter 12 is excellent in the uniformity of light in the outer peripheral direction, but the light tends to be diffused and the luminance tends to be weak in the other directions. Can be supplemented.

  With the configuration described above, in the third embodiment, it is not necessary to arrange several hundred light emitters at equal intervals, and surface emission can be achieved simply by arranging the line-shaped light emitters 12.

<Fourth embodiment>
Next, a fourth embodiment will be described based on FIG. FIG. 7 is a partially enlarged view of the X-ray CT apparatus according to the fourth embodiment, which basically has the same structure and operation as the third embodiment, but the arrangement location of the diffusion sheet 26 and the prism sheet 27 is different. . The diffusion sheet 26 and the prism sheet 27 are arranged in the stationary part 110 in the third embodiment, whereas in the fourth embodiment, the diffusion sheet 26 and the prism sheet 27 are arranged in the rotary scanner 111 and attached so as to cover the light receiving surface of the light receiving part 28. ing.

  Needless to say, the route of the light emitted from the light emitter 12 reaching the light emitter 12 → the diffusion sheet 26 → the prism sheet 27 → the light receiving unit 28 is the same as in the third embodiment, and the operation is the same. Further, the reflective sheet 15 is attached around the light emitter 12 as in the third embodiment.

  Based on the same concept as the second embodiment, the area that requires the diffusion sheet 26 and the prism sheet 27 may be smaller than that of the third embodiment. However, since the light emitter 12 has a bare structure, a protective film that sufficiently transmits light may be attached.

  From the third and fourth embodiments, a structure in which the diffusion sheet is arranged in the stationary part 110 and the prism sheet is arranged in the rotary scanner 111 is also conceivable.

<Fifth embodiment>
Next, a fifth embodiment will be described based on FIG. FIG. 8 is a partially enlarged view of the X-ray CT apparatus according to the fifth embodiment, in which the stationary part 110 and the rotary scanner 111 are moved in the centrifugal direction (that is, the direction orthogonal to the body axis direction of the subject placed on the bed). FIG. The fifth embodiment includes two signal transmission units according to the fourth embodiment and a non-contact power transmission mechanism, and the two signal transmission units are arranged at positions that are symmetrical in the centrifugal direction around the non-contact power transmission mechanism. Embodiment. The “position where the two signal transmission units are symmetrical in the centrifugal direction around the non-contact power transmission mechanism” means that the distance in the centrifugal direction between the non-contact power transmission mechanism and each signal transmission unit is substantially equal. Means position. Therefore, in the present embodiment, the distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3a is substantially equal to the distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3b. Are arranged as follows.

  The signal transmission unit includes a signal transmission unit 3a from the rotary scanner 111 to the stationary unit 110 and a signal transmission unit 3b from the stationary unit 110 to the rotary scanner 111, and transmits and receives two signals. The signal transmission unit 3a transmits a measurement signal and an X-ray feedback signal for feedback control of the X-ray output. The signal transmission unit 3b transmits a measurement trigger signal for starting capturing of the measurement signal. The signal transmission units 3a and 3b are provided at positions symmetrical with respect to the centrifugal direction with the mechanism provided on the rotary scanner 111 side of the non-contact power transmission mechanism 5 as a center. With this configuration, the fifth embodiment can achieve the smallest size of the rotary scanner as compared with the sixth embodiment and the seventh embodiment described later.

  In the fifth embodiment, a belt-like or square diffusion sheet 16 and prism sheet 17 are fixed to the stationary part 110 so as to cover the light receiving surface of the light receiving part 18 provided in the stationary part 110. Further, a belt-like or square diffusion sheet 26 and a prism sheet 27 are fixed to the rotary scanner 111 so as to cover the light receiving surface of the light receiving unit 28 provided in the rotary scanner 111.

  As in this embodiment, by providing a signal transmission unit that uses two systems of optical signals and a non-contact power transmission mechanism, it is possible to transmit signals and power in a non-contact manner, making maintenance easier. In addition, the reliability can be improved.

<Sixth Embodiment>
Next, a sixth embodiment will be described based on FIG. FIG. 9 is a partial enlarged view of the X-ray CT apparatus according to the sixth embodiment, and is a cross-sectional view of the stationary part 110 and the rotary scanner 111 cut in the centrifugal direction. In the sixth embodiment, the signal transmission units 3a and 3b are provided at positions that are point-symmetric about the central portion of the non-contact power transmission mechanism 5. The distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3a and the distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3b are substantially equal. The shapes and attachment positions of the diffusion sheets 16 and 26 and the prism sheets 17 and 27 are the same as in the fifth embodiment.

  In the sixth embodiment, as in the fifth embodiment, it is possible to transmit the signal and the power in a non-contact manner, the maintenance becomes simpler, and the reliability can be improved.

<Seventh embodiment>
Next, a seventh embodiment will be described based on FIG. FIG. 10 is a partial enlarged view of the X-ray CT apparatus according to the seventh embodiment, and is a cross-sectional view of the stationary part 110 and the rotary scanner 111 cut in the centrifugal direction. Also in the present embodiment, the distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3a and the distance in the centrifugal direction from the non-contact power transmission mechanism 5 to the signal transmission unit 3b are substantially equal. Be placed.

  The signal transmission direction of the signal transmission unit 3a and the signal transmission unit 3b is the centrifugal direction in the fifth embodiment, whereas in the seventh embodiment, the axial direction of the cylinder (the body axis of the subject placed on the bed) The same direction as the direction). With this configuration, the gap generated between the stationary part 110 and the rotary scanner 111 becomes simpler than in the fifth embodiment, so that the mechanism design that takes into account rotational fluctuations is relatively easy. Since there is a concern that the magnetic flux generated in the non-contact power transmission mechanism 5 leaks outside through the gap, a configuration for shielding the magnetic flux, for example, a shielding material may be appropriately disposed.

  In the present embodiment, hollow disk-shaped (doughnut-shaped) diffusion sheets 16 and 26 and prism sheets 17 and 27 are used, and the diffusion sheet 16 and the prism sheet 17 are covered so as to cover the light receiving unit 18 provided in the stationary part 110. Is fixed to the stationary unit 110, and the diffusion sheet 26 and the prism sheet 27 are fixed to the rotary scanner 111 so as to cover the light receiving unit 28 provided in the rotary scanner 111. Compared to the fifth embodiment and the sixth embodiment in which the belt-shaped diffusion sheets 16 and 26 and the prism sheets 17 and 27 are fixed along the circumferential direction, the hollow disk-shaped (doughnut-shaped) diffusion sheets 16 and 26 Using the prism sheets 17 and 27 makes it possible to simplify the sheet attaching operation.

  In the first to seventh embodiments, the effect does not change even if the relative positional relationship between the light emitter and the light receiving unit is reversed.

  Further, in the fifth to seventh embodiments, the signal transmission units 3a and 3b use the fourth embodiment, and the line-shaped light emitters 12 and 22 are arranged, but are shown in the first to third embodiments. Thus, the effect is the same even when the light emitter 11 which is a point light source is used.

  Further, in the fifth to seventh embodiments, the signal transmission units 3a and 3b use the fourth embodiment, and the diffusion sheets 16 and 26 and the prism sheets 17 and 27 are provided on the stationary unit 110 or the rotary scanner 111 with the photoreceptor 18, Although it is attached so as to cover 28, the effect is the same if it is attached so as to cover the light emitters 12 and 12 as shown in the first and third embodiments.

  In the first to seventh embodiments, the arrangement of the diffusion sheets 16 and 26 and the prism sheets 17 and 27 is divided into the stationary unit 110 and the rotary scanner 111, and the diffusion sheets 16 and 26 are divided into the stationary unit 110, the prism sheet 17, A structure in which 27 is arranged on the rotary scanner 111 has the same effect. Similarly, when light transmission / reception is reversed between the stationary unit 110 and the rotary scanner 111, the effect is the same even if the diffusion sheets 16 and 26 are in the rotary scanner 111 and the prism sheets 17 and 27 are in the stationary unit 110. Needless to say.

  Further, in the first to seventh embodiments, a brush or cloth having a small friction is attached to the stationary part 110 or the rotary scanner 111 so that the space between the stationary part 110 and the rotary scanner 111 slides in contact with the rotation. It may be configured. Such a brush or cloth is arranged so as to remove dust on the surface of the diffusion sheet or the prism sheet with rotation, and further improvement in maintainability can be expected.

  In the first to seventh embodiments, both the diffusion sheet and the prism sheet are used, but only one of them may be used. The configuration is as follows.

  An X-ray source that generates X-rays, an X-ray detector that is disposed opposite to the X-ray source, detects the X-rays that have passed through the subject, and outputs a measurement signal; the X-ray source and the X-rays A rotating scanner that mounts a detector and rotates the X-ray source and the X-ray detector around the subject; a stationary part that supports the rotating scanner; and the rotating scanner and the stationary part. In order to transmit and receive an optical signal, a signal transmission unit configured by a light emitter and a light receiver, and provided between the light emitter and the light receiver, for diffusing light emitted from the light emitter An X-ray CT apparatus comprising: a diffusion sheet; or a prism sheet for condensing light emitted from the light emitter toward the light receiving unit.

  3a, 3b Signal transmission unit, 5 Non-contact power transmission mechanism, 11 Light emitter, 12 Light emitter, 15 Reflector sheet, 16 Diffuser sheet, 17 Prism sheet, 18 Light receiver, 22 Light emitter, 25 Reflector sheet, 26 Diffuser sheet, 27 Prism sheet, 28 Receiver, 121a, 121b Light source, 81a, 81b Photodiode, 82a, 82b Amplifier, 83 OR, 100 X-ray CT device, 110 Stationary part, 111 Rotating part

Claims (1)

An X-ray source that generates X-rays, an X-ray detector that is disposed opposite to the X-ray source, detects the X-rays that have passed through the subject, and outputs a measurement signal; the X-ray source and the X-rays A rotating scanner that mounts a detector and rotates the X-ray source and the X-ray detector around the subject; a stationary part that supports the rotating scanner; and the rotating scanner and the stationary part. In order to transmit and receive an optical signal, a signal transmission unit configured by a light emitter and a light receiver, and provided between the light emitter and the light receiver, for diffusing light emitted from the light emitter A diffusion sheet, a prism sheet for condensing light emitted from the light emitter toward the light receiving unit, and a non-contact for transmitting power in a non-contact manner between the stationary unit and the rotary scanner An electric power mechanism ,
The signal transmission unit includes a first signal transmission unit that transmits the optical signal from the stationary unit to the rotary scanner, and a second signal transmission unit that transmits the optical signal from the rotary scanner to the stationary unit. The first signal transmission unit and the second signal transmission unit are arranged at positions that are symmetrical in the centrifugal direction of the rotational movement of the rotary scanner with the non-contact power mechanism as a center. X-ray CT apparatus according to.

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