JP4811038B2 - Radiation composite imaging device - Google Patents

Description

  The present invention captures an RI distribution image corresponding to the in-vivo distribution of a radioisotope (RI = radioisotope) administered to a subject and an X-ray CT image corresponding to an X-ray absorption distribution in the body of the subject. In particular, the present invention relates to a technique for increasing the degree of freedom during imaging.

  As a radiation composite imaging apparatus that captures an RI distribution image and an X-ray CT image, a PET-CT apparatus in which a PET (positron emission tomography) apparatus and an X-ray CT apparatus are combined is known. In the case of a conventional PET-CT apparatus, as shown in FIG. 12, a first gantry 92 for PET and an X-ray CT are arranged in series, with a top plate 91 on which a subject m is placed. The second gantry 93 is provided. The large gantry 92, 93 has an opening (tunnel) 92A, 93A through which the top 91 moves in and out while the subject m is placed, and a γ-ray detector 94 is provided in the first gantry 92. The second gantry 93 is provided with an X-ray tube 95 and an X-ray detector 96.

When an RI distribution image that provides biological function information of a subject is captured by a conventional apparatus, the RI that is administered to the subject m placed on the top 91 and entering the opening 92A of the first gantry 92 is applied. Γ-rays (annihilation γ-rays) with energy of 511 keV generated by the γ-ray detector 94 are detected. A γ-ray detection signal output from the γ-ray detector 94 is collected as emission data for acquiring RI distribution images, and a reconstruction process is performed based on the collected emission data to obtain a tomographic image type or a planar image type. The RI distribution image is acquired. In the case of the conventional apparatus, two annihilation γ-rays generated simultaneously by the disappearance of the positron of RI such as ¹¹ C administered to the subject m and proceeding in opposite directions were simultaneously detected by the γ-ray detector 94. In this case (when γ rays are counted simultaneously), emission data is collected.

  When an X-ray CT image that provides anatomical information of a subject is captured by a conventional apparatus, an X-ray tube is placed on the subject m that has been placed on the top 91 and entered the opening 93A of the second gantry 93. The X-ray is irradiated from 95 and the X-ray transmitted through the subject m is detected by the X-ray detector 96. An X-ray detection signal output from the X-ray detector 96 is collected as X-ray detection data for X-ray CT image acquisition, and a reconstruction process is performed based on the collected X-ray detection data to obtain an X-ray. A CT image is acquired. (For example, refer to Patent Document 1).

Japanese Patent No. 3404080 (pages 3 to 4, FIG. 1)

However, the conventional PET-CT apparatus has a problem that the degree of freedom at the time of photographing is small and the usefulness cannot be sufficiently exhibited.
The first reason that the degree of freedom during imaging is small is that the location where the RI distribution image and the X-ray CT image are captured is actually limited to the installation positions of the first and second gantry 92 and 93. Once the large first and second gantry 92, 93 are installed, it is almost impossible to move, and the imaging location is limited to the installation position of the gantry 92, 93. Can not be demonstrated.

A second reason for the low degree of freedom during imaging is that the subject m cannot be accessed during imaging. During imaging, the subject m is in the opening 92A of the first gantry 92 and the opening 93A of the second gantry 93, so that the subject m cannot be accessed in practice.
A third reason for the low degree of freedom during shooting is that other devices cannot coexist during shooting. Again, during imaging, the subject m is located in the opening 92A of the first gantry 92 or the opening 93A of the second gantry 93, so that both gantry 92, 93 may interfere with other devices. Can not.
If the subject m cannot be accessed during imaging, or if other equipment cannot be juxtaposed, surgery cannot be performed during imaging, or treatment cannot be performed in parallel with imaging. The usefulness of the CT apparatus cannot be fully exhibited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radiation composite imaging apparatus that has a high degree of freedom during imaging and can sufficiently demonstrate its usefulness.

In order to achieve such an object, the present invention has the following configuration.
That is, in the radiation composite imaging apparatus according to the first aspect of the present invention, (A) the γ-ray detector that detects γ-rays generated by the radioisotope (RI) administered to the subject has one end and the other end. A first C-shaped arm member disposed opposite to the first C-shaped arm member; (B) a first arm member conveying means for conveying the first C-shaped arm member ; and (C) a first C-shaped arm member along a curve of the first C-shaped arm member. A first arm member rotating means for rotating the letter-shaped arm member while rotating the first C-shaped arm member about a horizontal axis orthogonal to the rotation axis of the slide rotation, and (D) a γ-ray detector Emission data collecting means for collecting the output γ-ray detection signal as emission data for acquiring RI distribution images, and (E) an RI distribution image acquiring unit for acquiring RI distribution images based on the emission data. And (F) a second C-shaped arm member in which an X-ray tube for irradiating the subject with X-rays and an X-ray detector for detecting X-rays transmitted through the subject are disposed opposite one end and the other end And (G) second arm member conveying means for conveying the second C-shaped arm member, and (H) sliding and rotating the second C-shaped arm member along the bend of the second C-shaped arm member. A second arm member rotating means for rotating the second C-shaped arm member about a horizontal axis orthogonal to the rotation axis of rotation; and (I) an X-ray CT image representing an X-ray detection signal output from the X-ray detector. X-ray detection data collection means for collecting X-ray detection data for acquisition, and (J) X-ray CT image acquisition means for acquiring an X-ray CT image based on the X-ray detection data To do.

[Operation / Effect] In the case of taking an RI distribution image by the apparatus of the invention of claim 1, γ-ray detection is performed as the first arm member conveying means conveys the first C-shaped arm member together with the γ-ray detector. The instrument moves in parallel and the shooting location changes. Further, as the first arm member rotating means slides the first C-shaped arm member or rotates the horizontal axis around the rotation axis , the γ-ray detector rotates around the subject and the imaging direction changes. . That is, as the arrangement of the γ-ray detectors changes due to the conveyance and rotation of the first C-shaped arm member, the shooting location changes and the shooting direction changes.
On the other hand, during the acquisition of the RI distribution image, both γ-ray detectors installed at one end and the other end of the first C-shaped arm member emit γ-rays generated by the radioisotope (RI) administered to the subject. The detected γ-ray detection signal is output as emission data. On the other hand, the RI distribution image acquisition means acquires one or both of a tomographic type RI distribution image and a planar image type RI distribution image based on the emission data collected by the emission data collection means.

In the case of taking an X-ray CT image by the apparatus of the first aspect of the invention, the second arm member transporting means transports the second C-shaped arm member together with the X-ray tube and the X-ray detector. The X-ray detector and the X-ray detector move in parallel to change the imaging location. Further, as the second arm member rotating means slides the second C-shaped arm member or rotates the horizontal axis about the rotation axis , the X-ray tube and the X-ray detector rotate around the subject and the imaging direction Changes. That is, as the arrangement of the X-ray tube and the X-ray detector changes due to the conveyance and rotation of the second C-shaped arm member, the imaging location changes and the imaging direction changes.
On the other hand, during the acquisition of the X-ray CT image, the X-ray tube installed on the second C-shaped arm member irradiates the subject with the X-ray, and the X-ray detector detects the X-ray transmitted through the subject, and X A line detection signal is output as X-ray detection data. On the other hand, the X-ray CT image acquisition means acquires an X-ray CT image based on the X-ray detection data collected by the X-ray detection data collection means.

That is, in the case of the apparatus according to the first aspect of the invention, the RI distribution image or the X The imaging location and imaging direction of the X-ray CT image can be changed.
In addition, in the case of the apparatus of the invention of claim 1, the γ-ray detector, the X-ray tube and the X-ray detector are not installed in the gantry as in the prior art, but are first and second C-shaped. Since it is installed on the arm member, the practitioner can access the subject or place other devices in parallel during imaging.
Therefore, the radiation composite imaging apparatus according to the first aspect of the present invention has a high degree of freedom at the time of imaging and can sufficiently demonstrate its usefulness.

  According to a second aspect of the present invention, in the composite radiation imaging apparatus according to the first aspect, (K) an arrangement correspondence that recognizes a correspondence relation between the arrangement information of the γ-ray detector and the arrangement information of the X-ray detector. It has a relationship recognition means.

  [Operation / Effect] In the apparatus of the invention of claim 2, the same part of the subject is determined according to the correspondence between the arrangement information of the γ-ray detector recognized by the arrangement correspondence recognition means and the arrangement information of the X-ray detector. The RI distribution image and the X-ray CT image are acquired, or the acquired RI distribution image and the X-ray CT image are superimposed and displayed.

  The invention described in claim 3 includes: (L) detector contact / separation moving means for moving the γ-ray detector in a direction in which the γ-ray detector is in contact with and away from the subject; and (M) a first C-shape. Proximity control for moving the γ-ray detector toward the subject to an appropriate distance by moving the γ-ray detector toward and away from the subject while the arm member is rotating Proximity movement control means is provided.

  [Operation / Effect] In the apparatus of the invention of claim 3, when the γ-ray detector is brought close to the subject, the detection range of the γ-ray is expanded, and the sensitivity of the γ-ray detector is apparently increased. When the detector is separated from the subject, the γ-ray detection range is narrowed, and the sensitivity of the γ-ray detector is apparently reduced. Therefore, in the radiation composite imaging apparatus according to the third aspect of the invention, the proximity control by the proximity movement control means is performed on the detector contact / separation movement means so that the γ-ray detector is covered during the rotation of the first C-shaped arm member. The γ-ray detector can always maintain good sensitivity by moving the γ-ray detector closer to the subject to an appropriate distance by moving in the direction of contact with the specimen.

  According to a fourth aspect of the present invention, in the radiation composite imaging apparatus according to any one of the first to third aspects, the radioisotope administered to the subject is a positron type radioisotope, and the emission data The collecting means collects only γ-ray detection signals as emission data when annihilation γ-rays traveling in the opposite direction are simultaneously detected by the γ-ray detector.

  [Operation / Effect] In the case of the apparatus of the invention of claim 4, the annihilation γ-ray generated by the emission data collecting means accompanying the annihilation of the positron emitted from the radioisotope administered to the subject and traveling in the opposite direction is γ Since only the γ-ray detection signals simultaneously detected by the line detector are collected as emission data, an RI distribution image of the positron-type radioisotope administered to the subject can be taken.

In the case of the apparatus of the present invention, by changing the arrangement of the γ-ray detector, the X-ray tube, and the X-ray detector by conveying and rotating the first and second C-shaped arm members, the RI distribution image and X-ray CT image You can change the shooting location and direction.
In addition, in the case of the apparatus of the present invention, the γ-ray detector, the X-ray tube, and the X-ray detector are not installed in the gantry as in the prior art, but are attached to the first and second C-shaped arm members. Because it is installed, the practitioner can access the subject or place other devices alongside during imaging.
Therefore, the radiation composite image pickup apparatus of the present invention has a high degree of freedom at the time of photographing and can sufficiently exhibit its usefulness.

  Embodiment 1 of the radiation composite imaging apparatus of the present invention will be described. FIG. 1 is a block diagram showing the overall configuration of a PET (positron emission tomography) -CT apparatus according to the first embodiment, and FIG. 2 is a front view showing the configuration around the γ-ray detector of the apparatus according to the first embodiment. 3 is a side view showing the configuration around the γ-ray detector of the apparatus of Example 1, FIG. 4 is a front view showing the configuration of the apparatus of Example 1 around the X-ray tube and the X-ray detector, and FIG. It is a side view which shows the structure around the X-ray tube and X-ray detector of 1 apparatus.

  In the PET-CT apparatus of the first embodiment, as shown in FIGS. 1 to 3, γ-rays generated by positron emitting radioisotopes (RI) administered to the subject m on the top BD are detected. A first γ-ray detector 1 and a second γ-ray detector 2 are disposed opposite to one end and the other end of the first C-shaped arm member 3. In the first γ-ray detector 1 and the second γ-ray detector 2, a scintillator that converts incident γ-rays into light and a photomultiplier that converts light emitted from the scintillator into electricity and outputs it are arranged in multiple stages. It is a flat type two-dimensional detector.

  The apparatus according to the first embodiment conveys the fixed rail member 5 and the movable rail member 6 disposed along the ceiling 4, and the first C-shaped arm member 3 along the fixed rail member 5 and the movable rail member 6. A first arm member transport mechanism 7 is provided. The fixed rail member 5 is directly attached to the ceiling 4 so that the rail extends in a direction parallel to the body axis Z of the subject m (longitudinal direction of the top plate BD). The movable rail member 6 is suspended so as to be movable below the fixed rail member 5 in a direction in which the rail extends in a parallel direction perpendicular to the body axis Z of the subject m (short direction of the top plate BD).

  The first arm member transport mechanism 7 includes a first traveling unit 8 that travels while being guided by the fixed rail member 5 while the movable rail member 6 is suspended, and a first arm support member that holds the first C-shaped arm member 3. The second traveling unit 9 travels while being guided by the movable rail member 6 while the suspension 10 is suspended. And in the case of the 1st driving | running | working part 8, as the wheel drive part 8A act | operates and the wheel 8B rotates, the 1st driving | running | working part 8 tops the fixed rail member 5 with the movable rail member 6 on FIG. Drive in the direction indicated by. In the case of the second traveling unit 9, as the wheel driving unit 9A operates and the wheel 9B rotates, the second traveling unit 9 moves over the movable rail member 6 together with the first arm support member 10 in FIG. Drive in the direction indicated by. Accordingly, the first arm support member 10 moves in the direction indicated by the arrow RA in FIG. 2 by the travel of the first travel unit 8, and the first arm support member 10 by the travel of the second travel unit 9 by the arrow RB in FIG. Move in the direction shown.

On the other hand, the first C-shaped arm member 3 is attached to and held by the lower end portion of the first arm support member 10 via the first arm member rotation mechanism 11. As a result, as the first arm support member 10 moves as the first traveling unit 8 travels, the first C-shaped arm member 3 is conveyed in the direction indicated by the arrow RA in FIG. The first C-shaped arm member 3 is transported in the direction indicated by the arrow RB in FIG. 3 as the first arm support member 10 moves by traveling.
Thus, when the first C-shaped arm member 3 is transported, both the first and second γ-ray detectors 1 and 2 arranged on the first C-shaped arm member 3 are translated to change the imaging location. To do.

  On the other hand, the first C-shaped arm member 3 is attached to the lower end portion of the first arm support member 10 together with the first arm member rotating mechanism 11 while being supported by the first horizontal shaft member 12. Then, the first C-shaped arm member 3 is moved by the first arm member rotating mechanism 11 along the bend of the first C-shaped arm member 3 as shown by an arrow ra in FIG. As shown by the arrow rb in FIG. 3, the first C-shaped arm member 3 rotates sideways with the central axis of the first horizontal shaft member 12 supporting the first C-shaped arm member 3 as the rotation axis, as indicated by an arrow rb in FIG. It is set as the structure which can perform each horizontal rotation.

  The first arm member rotation mechanism 11 is provided with a rack 11A installed on the first C-shaped arm member 3 side, a pinion 11B installed on the first horizontal shaft member 12 side, and an electric motor 11C. Since the rack 11A engaged with the rotating pinion 11B is moved by the electric motor 11C, the first C-shaped arm member 3 slides along the bend of the first C-shaped arm member 3. Rotation takes place.

  In addition, the first arm member rotating mechanism 11 is provided with an electric motor 11a coaxially connected to the first horizontal shaft member 12, and the rotation of the electric motor 11a is transmitted to the first horizontal shaft member 12. When the first horizontal shaft member 12 rotates, the first C-shaped arm member 3 rotates sideways with the central axis of the first horizontal shaft member 12 as the rotation axis. When the first C-shaped arm member 3 rotates in this way, both the first and second γ-ray detectors 1 and 2 installed on the first C-shaped arm member 3 rotate around the subject m and the imaging direction. Changes.

  The first arm member transport mechanism 7 transports the first C-shaped arm member 3 while receiving transport control data according to an operator's operation or a preset program from the first transport control unit 13, and the first arm member 3 The rotation mechanism 11 rotates the first C-shaped arm member 3 while receiving rotation control data corresponding to an operator's operation or a preset program from the first rotation control unit 14. Further, the first transport control unit 13 sends transport control data for transporting the first C-shaped arm member 3 as transport position data indicating the transport positions of the first and second γ-ray detectors 1 and 2. The first rotation control unit 14 sends rotation control data for rotating the first C-shaped arm member 3 as rotation angle data indicating the rotation positions of the first and second γ-ray detectors 1 and 2. .

  Further, as shown in FIG. 1, the apparatus according to the first embodiment includes an emission data collection unit 15, an absorption correction unit 16, and an RI distribution image acquisition unit at the subsequent stage of the first and second γ-ray detectors 1 and 2. 17, a display monitor 18 that displays an RI distribution image, an X-ray CT image, or an operation menu of the apparatus, an operation unit 19 that inputs data and commands necessary for the operation of the apparatus, and the like. Has been.

The emission data collection unit 15 uses the γ-ray detection signals output from the first and second γ-ray detectors 1 and 2 as the transport position data for both the first and second γ-ray detectors 1 and 2. In addition, it is collected as emission data for acquiring RI distribution images while collating with rotation angle data and the like. In addition, in the case of the emission data collection unit 15, the annihilation γ-rays generated in association with the annihilation of positrons emitted from the radioisotope administered to the subject m and traveling in opposite directions are the first and second γ-rays. Only the γ-ray detection signals detected simultaneously by the detectors 1 and 2 are collected as emission data. That is, γ-ray detection when one of the annihilation γ-rays traveling in the opposite direction is detected by the first γ-ray detector 1 and at the same time the other γ-ray is detected by the second γ-ray detector 2. Only the signal is collected as emission data. Examples of positron-type RI administered to the subject m include ¹¹ C, ¹³ N, ¹⁵ O, and ¹⁸ F.

  The absorption correction unit 16 absorbs and corrects the emission data collected by the emission data collection unit 15. Specifically, the absorption correction unit 16 performs absorption correction using X-ray detection data (described in detail later). X-ray detection data is used as transmission data for absorption correction.

  The RI distribution image acquisition unit 17 performs a reconstruction process on the basis of the transport position data and the rotation angle data for both the first and second γ-ray detectors 1 and 2 in addition to the absorption data subjected to the absorption correction, and performs tomography. An image type RI distribution image and a planar image type RI distribution image are acquired. The display monitor 18 displays the RI distribution image acquired by the RI distribution image acquisition unit 17 on the screen. In the case of slide rotation, the first and second γ-ray detectors 1 and 2 do not rotate 360 °, and the rotation angle range is usually about 180 °, but even in the rotation angle range of about 180 °. There is no problem in obtaining a tomographic type RI distribution image.

  In addition, in the PET-CT apparatus of Example 1, as shown in FIGS. 4 and 5, the X-ray tube 21 that irradiates the subject m on the top BD irradiates X-rays and the X that has passed through the subject m. In addition to the X-ray detector 22 for detecting a line being placed opposite to one end and the other end of the second C-shaped arm member 23, the fixed rail member 5 disposed along the ceiling 4 and a movable A rail member 24 and a second arm member transport mechanism 25 that transports the second C-shaped arm member 23 along the fixed rail member 5 and the movable rail member 24 are provided. As described above, the fixed rail member 5 is attached to the ceiling 4 so that the rail extends in a direction parallel to the body axis Z of the subject m. The movable rail member 24 is suspended so as to be movable below the fixed rail member 5 in a direction in which the rail extends in a parallel direction perpendicular to the body axis Z of the subject m.

  The second arm member transport mechanism 25 includes a first traveling unit 26 that travels while being guided by the fixed rail member 5 while the movable rail member 24 is suspended, and a second arm support member that holds the second C-shaped arm member 23. And a second traveling portion 27 that travels while being guided by the movable rail member 24 while being suspended. And in the case of the 1st driving | running | working part 26, as the wheel drive part 26A act | operates and the wheel 26B rotates, the 1st driving | running | working part 26 tops the fixed rail member 5 with the movable rail member 24 in FIG. Drive in the direction indicated by. In the case of the second traveling unit 27, as the wheel driving unit 27A is activated and the wheel 27B rotates, the second traveling unit 27 moves over the movable rail member 27 together with the second arm support member 28 in FIG. Drive in the direction indicated by. Accordingly, the second arm support member 28 moves in the direction indicated by the arrow QA in FIG. 4 by the travel of the first travel unit 26, and the second arm support member 28 by the travel of the second travel unit 27 by the arrow QB in FIG. Move in the direction shown.

  On the other hand, the second C-shaped arm member 23 is attached to and held by the lower end portion of the second arm support member 28 via the second arm member rotation mechanism 29. As a result, as the second arm support member 28 moves as the first traveling unit 26 travels, the second C-shaped arm member 23 is conveyed in the direction indicated by the arrow QA in FIG. The second C-shaped arm member 23 is transported in the direction indicated by the arrow QB in FIG. 5 as the second arm support member 28 moves by traveling. Thus, when the second C-shaped arm member 23 is conveyed, the X-ray tube 21 and the X-ray detector 22 installed on the second C-shaped arm member 23 move in parallel to change the imaging location.

  On the other hand, the second C-shaped arm member 23 is attached to the lower end portion of the second arm support member 28 together with the second arm member rotating mechanism 29 while being supported by the second horizontal shaft member 30. Then, the second C-shaped arm member 23 is moved by the second arm member rotating mechanism 23 along the curve of the second C-shaped arm member 23 as shown by an arrow qa in FIG. As shown by an arrow qb in FIG. 5, the second C-shaped arm member 23 rotates sideways with the central axis of the second horizontal shaft member 30 that supports the second C-shaped arm member 23 as a rotation axis, as indicated by an arrow qb in FIG. It is set as the structure which can perform each horizontal rotation.

  The second arm member rotation mechanism 29 is provided with a rack 29A installed on the second C-shaped arm member 23 side, a pinion 29B installed on the second horizontal shaft member 30 side, and an electric motor 29C. Since the rack 29A engaged with the rotating pinion 29B is moved by the electric motor 29C, the second C-shaped arm member 23 slides along which the second C-shaped arm member 23 slides. Rotation takes place.

  In addition, the second arm member rotation mechanism 29 is provided with an electric motor 29 a coaxially connected to the second horizontal shaft member 30, and the rotation of the electric motor 29 a is transmitted to the second horizontal shaft member 30. When the second horizontal shaft member 30 rotates, the second C-shaped arm member 23 rotates sideways with the center axis of the second horizontal shaft member 30 as the rotation axis, and the second C-shaped arm member 23 rotates sideways. Thus, when the second C-shaped arm member 23 rotates, the X-ray tube 21 and the X-ray detector 22 installed on the second C-shaped arm member 23 rotate around the subject m to change the imaging direction. .

  The second arm member transport mechanism 25 transports the second C-shaped arm member 23 while receiving transport control data in accordance with an operator's operation or a preset program from the second transport control unit 31, and the second arm member The rotation mechanism 29 rotates the second C-shaped arm member 23 while receiving rotation control data corresponding to an operator's operation or a preset program from the second rotation control unit 32. Further, the second transport control unit 31 sends transport control data for transporting the second C-shaped arm member 23 as transport position data indicating the transport position of the X-ray detector 22, and the second rotation control unit 32 The angle control data for rotating the second C-shaped arm member 23 is sent as rotation angle data indicating the rotation position of the X-ray detector 22.

  Further, as shown in FIG. 1, the apparatus of the first embodiment is provided with an X-ray detection data collection unit 33 and an X-ray CT image acquisition unit 34 at the subsequent stage of the X-ray detector 22. The X-ray detection data collection unit 33 outputs an X-ray detection signal output from the X-ray detector 22 when the X-ray tube 21 emits X-rays according to the control of the X-ray irradiation control unit 21A. 22 is collected as X-ray detection data for acquiring an X-ray CT image while collating with conveyance position data, rotation angle data, and the like. The X-ray CT image acquisition unit 34 performs a reconstruction process based on the transport position data and rotation angle data for the X-ray detector 22 in addition to the collected X-ray detection data to obtain a tomographic X-ray CT image. To get. The acquired X-ray CT image is displayed on the screen of the display monitor 18 as necessary.

The main control unit 35 is mainly composed of a computer and its operation program, and sends a command or data to each unit in accordance with a command input from the operation unit 19 or a shooting progress state, thereby normalizing the apparatus. To play a role.

  In addition, as shown in FIG. 3, the apparatus according to the first embodiment is configured so that the γ-ray detectors 1 and 2 are in contact with and separated from the subject m by the first and second γ-ray detectors 1 and 2. 2 sets of detector contact / separation moving mechanisms 36 to be moved to each other, and the respective γ-ray detectors 1 and 2 are moved toward and away from the subject m while the first C-shaped arm member 3 is rotating. A proximity movement control unit 37 is provided that performs proximity control for each detector contact / separation movement mechanism 36 to bring the γ-ray detectors 1 and 2 close to the subject to an appropriate distance.

  When the first and second γ-ray detectors 1 and 2 are brought close to the subject m, the detection range of γ-rays is expanded, and the sensitivity of the γ-ray detectors 1 and 2 is apparently increased. When the detectors 1 and 2 are separated from the subject m, the γ-ray detection range is narrowed, and the sensitivity of the γ-ray detectors 1 and 2 apparently decreases. Therefore, as will be described in detail later, in the case of the apparatus according to the first embodiment, the first C-shaped arm member 3 is rotated by the proximity control performed by the proximity movement control unit 37 with respect to each detector contact / separation movement mechanism 36. As a result of the γ-ray detectors 1 and 2 moving in the direction of approaching and moving away from the subject m and approaching the subject m to an appropriate distance, the γ-ray detectors 1 and 2 always have good sensitivity. It is configured to be kept. Since the top plate BD is present under the subject m, when the first and second γ-ray detectors 1 and 2 are positioned on the back side of the top plate BD, proximity control considering the top plate BD is performed. This is performed for the first and second γ-ray detectors 1 and 2.

  Specifically, as shown in FIG. 3, the detector contact / separation moving mechanism 36 has a bar screw 36 </ b> B that is rotated by an electric motor 36 </ b> A, and the locking portions 1 a and 2 a of the γ-ray detectors 1 and 2. Are engaged with the respective bar screws 36B, and each of the γ-ray detectors 1 and 2 moves forward or forward as the bar screw 36B rotates and the locking portions 1a and 2a move along the respective bar screws 36B. It is configured to retreat. The proximity movement control unit 37 includes distance measuring sensors 37a and 37a that measure the distances between the γ-ray detectors 1 and 2 and the subject m, respectively (for example, ultrasonic type). The distance detected by the distance measuring sensors 37a and 37a by controlling the amount and direction of rotation of the electric motor 36A is set to a predetermined distance set as an appropriate distance to the subject m of the γ-ray detectors 1 and 2. It is configured to match.

However, since the positions of the γ-ray detectors 1 and 2 change as the first and second γ-ray detectors 1 and 2 are moved toward and away from the subject m, the proximity movement control is performed. The unit 37 sends the proximity control data as position variation data.
Therefore, in the case of the apparatus of the first embodiment, the arrangement information that defines the positions and orientations of the first and second γ-ray detectors 1 and 2 with respect to the mechanical origin of the apparatus is sent from the first transport control unit 13. Determined according to the transport position data, the rotation angle data sent from the first rotation control unit 14, and the position variation data sent from the proximity movement control unit 37.
In the case of the apparatus of the first embodiment, the arrangement information that defines the position and orientation of the X-ray detector 22 with respect to the mechanical origin of the apparatus includes the conveyance position data sent from the second conveyance control unit 31 and the second rotation. It is determined according to the rotation angle data sent from the control unit 32.

  Furthermore, the apparatus according to the first embodiment recognizes the correspondence between the arrangement information that defines the position and orientation of the γ-ray detectors 1 and 2 and the arrangement information that defines the position and orientation of the X-ray detector 22. RI distribution is provided for the same part of the subject m according to the correspondence between the arrangement information of the γ-ray detector and the arrangement information of the X-ray detector, which is provided with the relation recognition unit 38 and is recognized by the arrangement correspondence recognition unit 38. An image and an X-ray CT image are acquired, or the acquired RI distribution image and the X-ray CT image are displayed on the superimposed display monitor 18.

  On the other hand, as can be seen from the above, in the apparatus of the first embodiment, when the RI distribution image is taken, the positions and orientations of the first and second γ-ray detectors 1 and 2 with respect to the mechanical origin of the apparatus are determined. Since the imaging proceeds while changing, the reconstruction of the RI distribution image when the positions and orientations of the first and second γ-ray detectors 1 and 2 with respect to the mechanical origin of the apparatus change will be described below. The algorithm will be described.

  As shown in FIGS. 6 and 7, each of the first and second γ-ray detectors 1 and 2 is an assembly of minute γ-ray detection elements a and b. In the meantime, an image reconstruction area C having a center coordinate OC defined by a vector VC starting from the mechanical origin OM of the apparatus is set. Vectors VA and VB from the mechanical origin OM of the apparatus to the center coordinates OA and OB of the respective γ-ray detectors 1 and 2 are obtained based on the above-described transport position data, rotation angle data, and position variation data. The vectors WA and WB from the center coordinates WA and WB of the γ-ray detectors 1 and 2 to the γ-ray detection elements a and b are based on the addresses (coordinates) of the γ-ray detection elements a and b in the γ-ray detectors 1 and 2. Is required.

Accordingly, when a phenomenon occurs in which γ rays emitted from the subject m are simultaneously counted (hereinafter abbreviated as “event” as appropriate), a γ ray detecting element a that simultaneously detects γ rays from the mechanical origin OM of the apparatus. , B, the vectors uA and uB are also obtained according to the following equations (1) and (2).
uA = VA + WA (1)
uB = VB + WB (2)

On the other hand, when a phenomenon (event) in which γ rays emitted from the subject m are simultaneously counted occurs, address pair data of the γ ray detection elements a and b that detect γ rays, and γ that detects γ rays. Address pair data of vectors uA and uB for the line detection elements a and b are collected and stored as list mode type data for each event.
On the other hand, a straight line LOR (Line of Response) connecting γ-ray detection elements a and b that simultaneously detect γ-rays is obtained for each event from address pair data of vectors uA and uB collected and stored as list mode type data. The positron emitting species is above the straight line LOR.

  In this way, when a straight line LOR (Line of Response) connecting γ-ray detection elements a and b that simultaneously detect γ-rays is obtained for each event, a successive approximation list mode reconstruction algorithm is applied [ For example, see J Reader et al 1998 Phys. Med Bial. 43 835-846 (non-patent literature). The image update formula of this list mode reconstruction algorithm is as shown in formula (3). The RI distribution image is obtained by repeating the updating formula (3).

Here, f ^k _j is the pixel value of the pixel j in the k-th iteration, a _ij is the probability that the γ-ray emitted from the pixel j is detected by LORi, M is the number of measured events, and I is the main imaging condition It is the number of all LORs in (detector arrangement).
Note that the update formula used in the image reconstruction algorithm applied to the apparatus of the first embodiment is not limited to the formula (3).

As described above, in the case of the apparatus of the first embodiment, the first and second γ-ray detectors 1 and 2 and the X-ray tube 21 are conveyed by the conveyance and rotation of the first and second C-shaped arm members 3 and 23. Further, by changing the arrangement of the X-ray detector 22, the imaging location and imaging direction of the RI distribution image and X-ray CT image can be changed. In addition, in the case of the apparatus of the first embodiment, the first and second γ-ray detectors 1 and 2, the X-ray tube 21 and the X-ray detector 22 are not installed in the gantry as in the prior art, Since it is installed on the first and second C-shaped arm members 3 and 23, the practitioner can access the subject m or place other devices in parallel during imaging.
Therefore, the PET-CT apparatus according to the first embodiment has a high degree of freedom at the time of imaging, and can fully demonstrate its usefulness.

Next, the PET-CT apparatus of Example 2 will be described. FIG. 8 is a schematic view showing a configuration around the radiation imaging system of the PET-CT apparatus according to the second embodiment when viewed from the front. FIG. 9 is a schematic diagram showing a configuration around the radiation imaging system of the apparatus according to the second embodiment when viewed from the side. FIG.
The apparatus of the second embodiment is the same as the apparatus of the first embodiment except that the first horizontal shaft member 12 and the second horizontal shaft member 30 are coaxial and have a double cylinder structure, and the radiation imaging system is a biplane type. Therefore, only differences will be described, and description of common points will be omitted.

  Since the first horizontal shaft member 12 and the second horizontal shaft member 30 are coaxial and have a double cylinder structure, the first and second C-shaped arm members 3 and 23 are necessarily one arm member transport mechanism. Therefore, the first and second C-shaped arm members 3 and 23 are simultaneously conveyed and the first and second C-shaped arm members 3 and 23 are always in the same position.

Moreover, the 1st, 2nd C-shaped arm members 3 and 23 can each perform the slide rotation which slides along the curve of each C-shaped arm members 3 and 23, as shown by arrow ra (qa). The second C-shaped arm member 23 has a long hole 23A extending along the longitudinal direction, and the second C-shaped arm member 23 can slide without hitting the first horizontal shaft member 12.
Furthermore, the first and second C-shaped arm members 3 and 23 have a common center of the horizontal shaft members 12 and 30 that support the C-shaped arm members 3 and 23 as indicated by arrows rb (qb). Lateral rotation in which each C-shaped arm member 3, 23 rotates laterally about the axis as a rotation axis can also be performed.

  In the case of the apparatus according to the second embodiment, the RI distribution image and the X-ray CT image of the same part of the subject M can be taken substantially simultaneously. However, during X-ray imaging, the C-shaped arm members 3 and 23 are slightly displaced in the direction indicated by the arrow rb (qb) so that the first and second γ-ray detectors 1 and 2 do not get in the way. The first and second γ-ray detectors 1 and 2 are in a state of being retracted from the front of the X-ray tube 21 and the X-ray detector 22.

The present invention is not limited to the above embodiment, and can be modified as follows.
(1) The apparatus according to the first embodiment is configured such that the C-shaped arm members 3 and 23 on which the γ-ray detectors 1 and 2, the X-ray tube 21 and the X-ray detector 22 are installed are independently conveyed. However, as shown in FIG. 10, the first arm support member 10 and the second arm support member 28 may be connected by a connecting member 39 so that the C-shaped arm members 3 and 23 are integrally conveyed. Good.

  (2) In the apparatus according to the second embodiment, the C-shaped arm members 3 and 23 in which the γ-ray detectors 1 and 2, the X-ray tube 21 and the X-ray detector 22 are installed are arranged in the same direction. Although it was a biplane type, as shown in FIG. 11, it is good also as a biplane type in which C-shaped arm members 3 and 23 are located in a line with the C-shape facing each other.

  (3) The apparatus according to the embodiment is a ceiling traveling type in which each C-shaped arm member on which a γ-ray detector, an X-ray tube, and an X-ray detector are installed travels along a rail member disposed on the ceiling. However, either one or both of the C-shaped arm members on which the γ-ray detector, the X-ray tube, and the X-ray detector are installed travel along the rail member disposed on the floor. The floor traveling type configuration may be used.

  (4) Although the apparatus of Examples 1 and 2 was an apparatus in which a PET apparatus, which is a positron-type nuclear medicine imaging apparatus, was incorporated, this invention is a non-positron-type nuclear medicine imaging apparatus such as a SPECT apparatus. It can also be applied to built-in devices.

  (5) In the case of the apparatuses of the first and second embodiments, the positions and orientations of the first and second γ-ray detectors 1 and 2 and the X-ray detector 22 are the first and second transport control units 13 and 31. The position is determined according to the transport position data sent from the first, second rotation control units 14 and 32, and the position variation data sent from the proximity movement control unit 37. However, the structure which measures the position and direction of both the 1st, 2nd gamma ray detectors 1 and 2 and the X-ray detector 22 using a magnetic sensor or an optical sensor may be sufficient.

When using a magnetic sensor, for example, a transmitter that transmits radio waves in the three orthogonal directions is attached to each C-shaped arm member 3, 23, and the floor side is attached to each C-shaped arm member 3, 23. One receiver is arranged at each of three locations, and the positions of the first and second γ-ray detectors 1 and 2 and the X-ray detector 22 according to the reception signals output from the three receivers. And the direction is determined.
When using an optical sensor, for example, a mark piece is attached to each of the first C-shaped arm members 3 and 23, and optical cameras are arranged at three locations on the floor side for each of the C-shaped arm members 3 and 23. The positions and orientations of the first and second γ-ray detectors 1 and 2 and the X-ray detector 22 are determined according to video signals output from the three optical cameras.

  (6) In the first and second embodiments, the distance between the γ-ray detectors 1 and 2 and the subject m is measured by the distance measuring sensor 37a. The distance may be measured using a tomographic type RI distribution image or an X-ray CT image. A tomographic-type RI distribution image and X-ray CT image at the transport position of the γ-ray detectors 1 and 2 are acquired, and the contour position of the subject m in the RI distribution image and X-ray CT image and the γ-ray detector 1 are further acquired. , 2, the distance between the γ-ray detectors 1, 2 and the subject m is obtained based on the rotation angle data.

  (7) In the first and second embodiments, each of the X-ray tube 21 and the X-ray detector 22 is moved in the direction in which the X-ray tube 21 and the X-ray detector 22 are moved toward and away from the subject m, similarly to the γ-ray detectors 1 and 2. Devices having the same configuration as those of the first and second embodiments can be cited as modifications.

1 is a block diagram illustrating an overall configuration of a PET-CT apparatus according to Embodiment 1. FIG. FIG. 3 is a front view illustrating a configuration around a γ-ray detector of the apparatus according to the first embodiment. It is a side view which shows the structure around the gamma-ray detector of the apparatus of Example 1. FIG. It is a front view which shows the structure around the X-ray tube and X-ray detector of the apparatus of Example 1. FIG. It is a side view which shows the structure around the X-ray tube and X-ray detector of the apparatus of Example 1. FIG. 3 is a schematic diagram illustrating an arrangement relationship between a γ-ray detector and an image reconstruction area in the apparatus according to the first embodiment. 3 is a graph showing a coordinate system of a γ-ray detector and an image reconstruction area in the apparatus of Example 1; It is the schematic which shows the structure around the radiation imaging system of the apparatus of Example 2 seeing from the front. It is the schematic which shows the structure around the radiation imaging system of the apparatus of Example 2 seeing from a side surface. FIG. 6 is a schematic diagram illustrating a configuration around a radiation imaging system of a modification of the apparatus according to the first embodiment. FIG. 10 is a schematic diagram illustrating a configuration around a radiation imaging system of a modification of the apparatus according to the second embodiment. It is a front view which shows the structure of the gantry of the conventional PET-CT apparatus.

Explanation of symbols

1 ... 1st gamma ray detector (gamma ray detector)
2 ... Second γ-ray detector (γ-ray detector)
3 ... 1C-shaped arm member 7 ... 1st arm member conveyance mechanism (1st arm member conveyance means)
11: First arm member rotating mechanism (first arm member rotating means)
15 ... Emission data collection unit (Emission data collection means)
17 ... RI distribution image acquisition unit (RI distribution image acquisition means)
DESCRIPTION OF SYMBOLS 21 ... X-ray tube 22 ... X-ray detector 23 ... 2C-shaped arm member 25 ... 2nd arm member conveyance mechanism (2nd arm member conveyance means)
29 ... Second arm member rotating mechanism (second arm member rotating means)
33 ... X-ray detection data collection unit (X-ray detection data collection means)
34 ... X-ray CT image acquisition unit (X-ray CT image acquisition means)
36 ... Detector contact / separation movement mechanism (detector contact / separation movement means)
37 ... Proximity movement control unit (proximity movement control means)
38: Arrangement correspondence recognition unit (arrangement correspondence recognition means)
m… Subject

Claims (4)

(A) a first C-shaped arm member in which a γ-ray detector for detecting γ-rays generated by a radioisotope (RI) administered to a subject is disposed opposite one end and the other end; and (B) First arm member conveying means for conveying the first C-shaped arm member; and (C) rotating the first C-shaped arm member along the bend of the first C-shaped arm member, and a rotation axis of the sliding rotation; First arm member rotating means for rotating the first C-shaped arm member with the orthogonal horizontal axis as the rotation axis , and (D) a γ-ray detection signal output from the γ-ray detector as emission data for acquiring RI distribution images Emission data collection means for collecting, (E) RI distribution image acquisition means for acquiring an RI distribution image based on the emission data, (F) An X-ray tube for irradiating the subject with X-rays and the subject transmitted A second C-shaped arm member in which an X-ray detector for detecting a line is oppositely installed at one end and the other end; (G) a second arm member conveying means for conveying the second C-shaped arm member; H) The second C-shaped arm member is slid and rotated along the bend of the second C-shaped arm member, and the second C-shaped arm member is rotated about the horizontal axis orthogonal to the rotation axis of the sliding rotation . Two-arm member rotating means, (I) X-ray detection data collecting means for collecting X-ray detection signals output from the X-ray detector as X-ray detection data for X-ray CT image acquisition, and (J) X-rays An X-ray CT image acquisition unit that acquires an X-ray CT image based on detection data.   The radiation composite imaging apparatus according to claim 1, further comprising: (K) an arrangement correspondence recognition means for recognizing a correspondence relation between the arrangement information of the γ-ray detector and the arrangement information of the X-ray detector. .   The radiation composite imaging apparatus according to claim 1 or 2, wherein (L) detector contact / separation moving means for moving the γ-ray detector in a direction in which the γ-ray detector contacts and separates from the subject; Proximity control for moving the γ-ray detector closer to the subject to an appropriate distance by moving the γ-ray detector toward and away from the subject during rotation of the first C-shaped arm member. A radiation composite imaging apparatus comprising proximity movement control means for performing the above operation. 4. The annihilation γ-ray according to claim 1, wherein the radioisotope administered to the subject is a positron-type radioisotope, and the emission data collection means advances in the opposite direction. A radiation composite imaging apparatus that collects only γ-ray detection signals when emission is simultaneously detected by a γ-ray detector as emission data.

Images