JP2015008849A - Radiation tomography apparatus and radiation tomography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation tomography apparatus capable of accurately performing tomosynthesis imaging on a patient or like with difficulty of standing up while suppressing an introduction cost by using existing equipment of a facility.SOLUTION: A radiation tomography apparatus 1 includes a radiation detector F which acquires a projection image S with a plurality of radiation detection elements 7 arranged on a surface 4a of a substrate 4, a radiation source 61 which irradiates the radiation detector F with radiation via a subject H, a subject table 70 which holds the subject H, and a conveyance device 71 which moves the subject table 70 in a prescribed direction. The conveyance device 71 moves the subject H held by the subject table 70 in a direction parallel to the extension direction of the surface 4a of the substrate 4 of the radiation detector F between the radiation source 61 and the radiation detector F whose positions are fixed by moving the subject table 70. The radiation detector F performs a predetermined number of acquiring processing of the projection image while the conveyance device 71 moves the subject table 70 to move the subject H.

Description

  The present invention relates to a radiation tomography apparatus and a radiation tomography system.

  Conventionally, a radiation tomography apparatus that performs tomosynthesis imaging that irradiates a patient's body, which is a subject, from the surroundings, converts the radiation transmitted through the subject into an electrical signal, and obtains the converted electrical signal as a projection image has been medically used. It is used in the field of Then, a two-dimensional or three-dimensional tomographic image of a predetermined cross section of the subject is generated by reconstructing a plurality of projection images of the subject acquired by the radiation tomography apparatus by the image processing device.

  As a radiation tomography apparatus, a CT (computer tomography) apparatus, that is, a radiation source and a radiation detector, which are paired with each other with a subject interposed therebetween, spirals around the subject's body axis. A helical scan CT method that detects the intensity of transmitted radiation as a projected image at a number of rotational positions while rotating and moving is well known.

  However, in such a CT apparatus, since the gantry having at least one radiation source and at least one radiation detector rotates around the patient's body as a subject, the apparatus tends to increase in size. In addition, CT apparatuses are generally expensive, and there are problems such as high introduction costs when newly introduced into a facility such as a hospital.

  Therefore, for example, by using a radiation source or radiation detector already installed in a facility such as a hospital, the introduction cost can be reduced, and, similarly to the CT apparatus, the radiation source and the radiation detector are relatively placed on the subject. A radiation tomography apparatus has been proposed in which a projection image in a direction orthogonal to the patient's body axis (hereinafter, this direction is referred to as the body thickness direction) can be taken by rotating around the patient's body axis. (See, for example, Patent Documents 1 and 2).

  That is, for example, in the radiation tomography apparatuses described in Patent Documents 1 and 2, the radiation source and radiation are not rotated around the subject as in the CT apparatus, but the positions of the radiation source and the radiation are fixed. A rotating table is provided between the detectors, and the patient stands on the rotating table and rotates the rotating table to rotate the patient's body as a subject. And it is comprised so that a projection image may be acquired by irradiating the subject in that state with radiation from a radiation source.

  With such a configuration, in such a radiation tomography apparatus, similarly to the CT apparatus, the radiation source and the radiation detector are relatively rotated around the body axis of the patient as a subject to obtain a projection image. By reconstructing the acquired projection image, it is possible to generate a two-dimensional or three-dimensional tomographic image equivalent to the case of the CT apparatus.

  In addition, since a radiation source and radiation detector already installed in a facility such as a hospital can be used, a turntable is provided, or the rotation of the turntable and the timing of radiation irradiation from the radiation source are synchronized. Such a configuration has the advantage that the radiation tomography apparatus can be introduced into the facility at a very low cost.

JP 2003-319935 A JP 2005-296340 A

However, in the radiation tomography apparatuses described in Patent Documents 1 and 2, as described above, it may not always be easy for the patient who rotates with the rotation of the turntable to maintain the same posture. In addition, disorder in the posture of the patient in the Z direction (floor to ceiling direction) in each rotational phase (patient motion in the body axis direction) may cause artifacts in the reconstructed tomographic image, leading to misdiagnosis. there were.
Further, there is no proposal for a configuration that can use existing equipment to generate a tomographic image in a direction parallel to the body axis direction, that is, a coronal image (a coronal section image).

  As a result of repeated research under such circumstances, the present inventors have reduced the introduction cost by using a radiation source or radiation detector already installed in a facility such as a hospital as described above. However, radiation tomography can be performed accurately even for patients who cannot stand or cannot maintain the same posture as described above. We were able to develop a radiation tomography device that can be generated and a radiation tomography system using it.

  The present invention has been made in view of the above points, and tomosynthesis imaging can be accurately performed even on a patient who is difficult to stand up while suppressing the introduction cost by using existing equipment in the facility. An object of the present invention is to provide a radiation tomography apparatus capable of performing a coronal image and a radiation tomography system using the same.

In order to solve the above problems, the radiation tomography apparatus and radiation tomography system of the present invention are:
A plurality of radiation detectors arranged two-dimensionally on one surface of the substrate, a radiation detector that converts the irradiated radiation into an electric charge and obtains it as a projection image;
A radiation source that irradiates the radiation detector with radiation through a subject;
A subject table for holding the subject;
A transfer device for moving the subject table in a predetermined direction;
With
The transfer device moves the subject table to move the subject held on the subject table between the radiation detector and the radiation source whose position is fixed, on the substrate of the radiation detector. Move in a direction parallel to the direction of the surface extension,
The radiation detector is characterized in that the transfer device moves the subject table and performs the projection image acquisition process a predetermined number of times with different subject positions.

  According to the radiation tomography apparatus of the system as in the present invention, the subject is an extension of the substrate surface of the radiation detector with respect to the radiation source whose position is fixed while the patient as the subject is held on the subject table. It moves in a direction parallel to the current direction. Therefore, it is possible to automatically obtain a projection image by moving the subject and the radiation source relative to a patient who is difficult to stand up as well as a patient who can stand up as a subject. It becomes possible, and tomosynthesis imaging can be performed accurately.

  In addition, since it is possible to configure a radiation tomography apparatus without using any existing radiation source or imaging table in the facility, and without any modification to itself, the introduction cost of the radiation tomography apparatus is Only the newly introduced subject table, transport device, etc. are sufficient. For this reason, it is possible to accurately suppress an increase in the cost of introducing the radiation tomography apparatus and the radiation tomography system into the facility, and to introduce the radiation tomography apparatus and the radiation tomography system into the facility at a low cost. Then, it is possible to generate a coronal image using existing equipment.

It is a figure showing the whole radiation tomography system composition concerning this embodiment. It is sectional drawing of a radiation detector. It is a top view which shows the structure of the board | substrate of a radiation detector. It is a block diagram showing the equivalent circuit of a radiation detector. It is a perspective view showing the state which connected the connector of the cable to the connector of the radiation detector. It is the schematic which shows the structure of the radiation tomography apparatus which concerns on this embodiment. It is a figure explaining the start position and end position of a subject's movement. It is the figure which looked at the imaging | photography stand from upper direction, and is a figure explaining the state which has arrange | positioned the radiation detector in the state which inclined 45 degrees with respect to the body axis of the to-be-photographed object. (A), (B) It is a figure explaining a coronal image. It is the schematic which shows the structure of the radiation tomography apparatus in the modification 1. FIG. 10 is a diagram illustrating a state in which tomosynthesis imaging is performed by moving a radiation detector in accordance with movement of a subject in Modification 1; It is the figure which looked at the cover board unit from the radiation source side, and is a figure explaining the structure of a cover board unit.

  Embodiments of a radiation tomography apparatus and a radiation tomography system according to the present invention will be described below with reference to the drawings.

  In the following description, the radiation detector F used in the radiation tomography system 100 is provided with a scintillator or the like, and is a so-called indirect type that obtains an electrical signal by converting emitted radiation into electromagnetic waves of other wavelengths such as visible light. Although the radiation detector will be described, the present invention can also be applied to a so-called direct type radiation detector that directly detects radiation with a radiation detection element without using a scintillator or the like.

  The radiation detector F is a so-called portable type (also referred to as a cassette type or the like), and is loaded into a loading unit 51 (see FIG. 1 described later) of the imaging table 50 constituting the radiation tomography apparatus 1. Although the case of performing radiation tomography will be described, the present invention is also applied to a so-called special-purpose type radiation detector in which the radiation detector F is not portable and is formed integrally with the imaging table 50. It is possible.

  First, a schematic configuration of the radiation tomography system according to the present embodiment will be described. FIG. 1 is a diagram showing a schematic configuration of a radiation tomography system according to the present embodiment. In the present embodiment, as shown in FIG. 1, the radiation tomography system 100 is mainly configured by a radiation tomography apparatus 1 including a radiation detector F, an image processing apparatus 90, and the like.

  In this embodiment, as shown in FIG. 1, the radiation tomography apparatus 1 includes an imaging table 50 including a radiation detector F and a loading unit (also referred to as a cassette holder) 51 on which the radiation detector F is loaded. The radiation irradiation device 60 includes a radiation source 61 and the like, a subject table 70 that holds the subject H, a transport device 71 that moves the subject table 70 in a predetermined direction, and the like.

  In the present embodiment, as will be described later, as the imaging table 50 of the radiation tomography apparatus 1, an imaging table (also referred to as a bucky device) already installed in the facility is used. Moreover, the existing radiation irradiation apparatus in the facility is used as the radiation irradiation apparatus 60 including the radiation source 61 and the like. The configuration of the radiation tomography apparatus 1 will be described in detail later.

  On the other hand, in this embodiment, the radiation tomography system 100 is provided inside and outside the imaging room 101a and the front room (also referred to as an operation room) 101b, and the imaging table 50 of the radiation tomography apparatus 1 A radiation source 61 and the like are provided in the imaging room 101a. In the radiographing room 101a, an access point 95 for relaying wireless communication between the radiation detector F and a console 90 described later is also provided.

  In the present embodiment, the front chamber (also referred to as an operation room or the like) 101b is provided with the operation unit 62 of the radiation irradiation device 60, the exposure button 63, and the like. Further, FIG. 1 shows a case where the control BOX 80, the console 90, and the like are provided outside the front chamber 101b, but they can also be provided inside the front chamber 101b.

  A control BOX (also referred to as a repeater or the like) 80 is connected to the radiation tomography apparatus 1, the radiation irradiation apparatus 60, the console 90, and the like via a network N1. The control BOX 80 converts a LAN (Local Area Network) communication signal transmitted from the console 58 or the like to the radiation irradiation device 60 into a signal for the radiation irradiation device 60 or vice versa. A converter (not shown) is built in.

  The console 90 is provided with a display unit 91 including a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), and the like, and includes an input unit 92 such as a mouse and a keyboard. In addition, the console 90 is connected to or includes a storage means (not shown) configured by an HDD (Hard Disk Drive) or the like.

  The console 90 controls the radiation detector F by, for example, transmitting a wake-up signal to the radiation detector F to change the radiation detector F from a sleep state to a wake-up state. A tube current or the like set on the console 90 by a radiographer or other photographer can be transmitted and set to the radiation irradiation device 60 via the control BOX 80.

  In the present embodiment, the console 90 also functions as an image processing apparatus. When a projection image acquired by the radiation detector F is transmitted from the radiation tomography apparatus 1 as described later, These are reconstructed to generate a two-dimensional or three-dimensional tomographic image of the subject. For reconstruction, techniques such as an FBP (Filtered Back Projection) method and a successive approximation image reconstruction method can be used. In addition, the image processing apparatus can be configured as a separate apparatus from the console 90.

  Further, as shown in FIG. 1, an access point 95 is connected to the console 90 via a network N2. In addition, the console 90 is connected via a network N2 to a non-illustrated HIS (Hospital Information System), RIS (Radiology Information System), PACS (Picture Archiving and Communication System). Etc. are connected. The console 90 is configured to perform various processes such as obtaining imaging order information necessary for imaging from the RIS and transmitting the generated tomographic image to the PACS.

  In the radiation tomography system 100 shown in FIG. 1, the imaging table 50 and the radiation irradiation device 60 are already installed in a facility such as a hospital, and the console 90 is connected to the HIS, RIS, PACS, etc. via the network N2. In this place, a new subject table 70, transport device 71, control BOX 80, etc. are introduced, and the existing imaging table 50, radiation irradiation device 60, console 90, etc. are newly connected via the network N1 to provide radiation. The case where the tomography system 100 is constructed is shown.

  However, it is not necessary to divide and configure the network connecting the devices by a plurality of networks N1 and N2 as in this embodiment, and configure the radiation tomography system 100 by connecting each device to one network. Is also possible. Further, when a plurality of networks are used as a network connecting the devices as in the present embodiment, which device is connected to which network can be changed as appropriate.

[Radiation detector]
Here, the structure of the radiation detector F which comprises the radiation tomography apparatus 1 which concerns on this embodiment is demonstrated easily. FIG. 2 is a cross-sectional view of the radiation detector according to the present embodiment, and FIG. 3 is a plan view showing the configuration of the substrate of the radiation detector.

  As shown in FIG. 2, the radiation detector F is configured by housing a sensor panel SP including a scintillator 3, a substrate 4, and the like in a housing 2. A radiation incident surface R on which radiation is irradiated is formed on one side of the housing 2. Although not shown, in the present embodiment, the housing 2 is provided with an antenna device 41 (see FIG. 4 described later) for transmitting a projection image S described later in a wireless manner.

  As shown in FIG. 2, the substrate 4 is provided on the radiation incident surface R side of the base 31 arranged in the housing 2 via a lead thin plate (not shown). A scintillator 3 that converts the irradiated radiation into light such as visible light is provided on the radiation incident surface R side of the substrate 4, and the scintillator 3 is supported by a scintillator substrate 34.

  Further, on the side opposite to the radiation incident surface R side of the base 31, a PCB substrate 33 on which electronic components 32 and the like are disposed, a battery 24, and the like are attached. In this way, the sensor panel SP is formed by the base 31, the substrate 4, and the like. In the present embodiment, the buffer material 35 is provided between the sensor panel SP and the side surface of the housing 2.

  In the present embodiment, the substrate 4 is made of a glass substrate. As shown in FIG. 3, a plurality of scanning lines 5 and a plurality of signal lines 6 are arranged on one surface 4 a (hereinafter referred to as “surface 4 a”) side of the substrate 4, that is, on the surface 4 a facing the scintillator 3. Radiation detection elements 7 are respectively provided in the small areas r that are arranged so as to intersect with each other and are partitioned by the scanning lines 5 and the signal lines 6.

  Thus, a region where a plurality of radiation detection elements 7 arranged in a two-dimensional shape (matrix) is provided (that is, a region indicated by a one-dot chain line in FIG. 3) is a detection unit P. In the present embodiment, a photodiode is used as the radiation detection element 7, but a phototransistor or the like can also be used, for example.

  Here, the circuit configuration of the radiation detector F will be described. FIG. 4 is a block diagram showing an equivalent circuit of the radiation detector F according to this embodiment.

  The source electrode 8s (see “S” in FIG. 4) of the TFT 8 serving as the switch element is connected to the first electrode 7a of each radiation detection element 7, and the drain electrode 8d and the gate electrode 8g of the TFT 8 (“D” in FIG. 4). ”And“ G ”) are connected to the signal line 6 and the scanning line 5, respectively.

  In the present embodiment, as shown in FIG. 3 and FIG. 4, the bias line is applied to the second electrode 7 b of each radiation detection element 7 at a ratio of one for each radiation detection element 7 in a row on the substrate 4. 9 is connected, and each bias line 9 is connected to the connection 10 at a position outside the detection portion P of the substrate 4. The connection 10 is connected to a bias power supply 14 (see FIG. 4) via an input / output terminal (also referred to as a pad; see FIG. 3) 11. A reverse bias voltage is applied to the second electrode 7 b of the radiation detection element 7.

  On the other hand, each scanning line 5 is connected to the gate driver 15b of the scanning driving means 15 via the input / output terminal 11, respectively. In the scanning drive means 15, an on-voltage and an off-voltage are supplied from the power supply circuit 15 a to the gate driver 15 b through the wiring 15 c, and the gate driver 15 b is applied to each line L 1 to Lx of the scanning line 5. The voltage to be switched is switched between an on voltage and an off voltage.

  Each signal line 6 is connected to each readout circuit 17 built in the readout IC 16 via each input / output terminal 11. In the present embodiment, the readout circuit 17 is mainly composed of an amplification circuit 18 and a correlated double sampling circuit 19. An analog multiplexer 21 and an A / D converter 20 are further provided in the read IC 16. In FIG. 4, the correlated double sampling circuit 19 is denoted as CDS.

  The readout circuit 17 and the like perform a process of acquiring the projection image S from each radiation detection element 7 based on the control of the control unit 22 described later.

  Specifically, when an ON voltage is applied to the TFT 8 of each radiation detection element 7 and the TFT 8 is turned on, electric charges generated by radiation irradiation are emitted from the radiation detection elements 7 to the signal lines 6, respectively. It flows into the amplifier circuit 18 of each readout circuit 17. The amplification circuit 18 outputs a voltage value corresponding to the amount of charge that has flowed in. The correlated double sampling circuit 19 outputs the output value from the amplification circuit 18 before and after the charge flows from each radiation detection element 7. Is output to the downstream side as a projection image S of an analog value.

  Then, the output projection image S is sequentially transmitted to the A / D converter 20 via the analog multiplexer 21, and is sequentially converted into a digital projection image S by the A / D converter 20 and output to the storage means 23. Are stored sequentially. In this way, the acquisition process of the projection image S is performed.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc., not shown, connected to a bus, an FPGA (Field Programmable Gate Array), or the like. It is configured. It may be configured by a dedicated control circuit.

  Then, the control unit 22 controls the operation of each functional unit of the radiation detector F, such as controlling the scan driving unit 15 and the readout circuit 17 to perform the acquisition process of the projection image S as described above. It has become. Further, as shown in FIG. 4 and the like, the control means 22 is connected to a storage means 23 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM) or the like.

  In this embodiment, the control unit 22 is connected to a battery 24 that supplies power necessary for each functional unit such as the scanning drive unit 15, the readout circuit 17, the storage unit 23, and the bias power source 14. The control unit 22 is connected to the antenna device 41 described above, and the control unit 22 of the radiation detector F is connected to the console 90 from the antenna device 41 via the access point 95 (see FIG. 1). It is possible to transmit and receive signals, data, and the like with an external device such as a wireless method.

  In this embodiment, a connector 39 is provided on the side surface of the housing 2 of the radiation detector F. As shown in FIG. 5, the tip of the cable Ca provided on the imaging stand 50 is connected to the connector 39. By connecting the connector C provided to the control unit 22, the control means 22 can transmit and receive signals and data to and from an external device such as the console 90 via the connector 39 and the like. ing.

  In FIG. 5, reference numerals 37 and 38 denote a power switch and a changeover switch of the radiation detector F, and reference numeral 40 denotes an indicator that indicates an operating state of the control means 22. The cable Ca is connected to the connector 39 of the radiation detector F when the radiation detector F is loaded into the loading unit 51 (see FIG. 1) of the imaging stand 50.

  The cable Ca is connected to the network N1 (see FIG. 1) via the imaging stand 50, and the radiation detector F communicates with the console 90 and the like via the cable Ca and the network N1. Yes. However, the radiation detector F loaded in the loading unit 51 of the imaging stand 50 communicates with the console 90 and the like wirelessly via the antenna device 41 (see FIG. 4) and the access point 95 (see FIG. 1). As described above, it can be configured.

  Further, when the cable Ca is connected to the connector 39 of the radiation detector F, power is supplied to the radiation detector F from the external commercial power supply or the power supply unit of the imaging stand 50 via the cable Ca. It is also possible. In that case, the supply of power from the battery 24 (see FIG. 4) built in the radiation detector F to each functional unit in the radiation detector F can be stopped. According to this configuration, the power is not cut off during shooting.

  In addition, since tomographic imaging is performed with a large number of images taken per predetermined time (a large frame rate), the transfer time of the captured image data (projected image) is shortened, and duplication of imaging and data transfer is reduced. It is preferable that the radiation detector F and the console 90 are connected by cable Ca directly or via the imaging table 50 so that no noise is generated in both cases.

[Radiation tomography equipment]
Next, the configuration of the radiation tomography apparatus 1 according to this embodiment will be described. FIG. 6 is a schematic diagram showing the configuration of the radiation tomography apparatus 1 according to the present embodiment. FIG. 6 shows a case where the subject H is lying down with the head on the near side.

  In the present embodiment, the radiation tomography apparatus 1 mainly includes a radiation detector F, an imaging table 50, a radiation irradiation device 60, a subject table 70, and a transport device 71. The radiation detector F is as described above and will not be described here.

  The imaging table 50 includes a loading unit 51 and a support table (also referred to as a top plate) 52, and the radiation detector F is loaded into the loading unit 51 of the imaging table 50.

  In the present embodiment, as described above, as the imaging stand 50, the imaging stand for the supine position already installed in the facility is used, and thus the existing imaging stand 50 is used in the facility. By doing so, it is possible to suppress an increase in the cost of introducing the radiation tomography apparatus 1 into the facility, but the present invention is not limited to the case where the existing imaging stand 50 is used in the facility.

  In the radiation tomography apparatus 1 shown in FIG. 6, as described above, since the imaging table for the supine imaging is used as the imaging table 50, the radiation detector F of the imaging table 50 is used as described above. When loaded in the loading unit 51, the radiation detector F has the surface 4a (see FIG. 3) of the substrate 4 on which the plurality of radiation detection elements 7 are arranged on the floor surface on which the radiation tomography apparatus 1 is installed. It will be in the state arrange | positioned in parallel with respect to (illustration omitted). That is, in this case, the extending direction of the surface 4a of the substrate 4 of the radiation detector F is directed in the horizontal direction.

  In the present embodiment, the radiation irradiation apparatus 60 is also configured such that the existing radiation irradiation apparatus 60 is used in the facility in order to suppress a rise in the cost of introducing the radiation tomography apparatus 1 into the facility. It is not limited to such a case.

  The radiation irradiation device 60 includes a radiation source 61 that irradiates the radiation detector F via the subject H, a console 62 that allows a radiographer or other photographer to set tube current, tube voltage, irradiation time, and the like, The exposure switch 63 or the like is operated by the photographer to instruct the irradiation of radiation from the radiation source 61.

  In the present embodiment, as the radiation source 61 of the radiation irradiation apparatus 60, a radiation source that irradiates radiation toward the subject H or the radiation detector F in a cone shape, that is, a radiation source that irradiates a so-called cone beam is used. The radiation source 61 may be configured to use a radiation source that irradiates radiation that spreads in a substantially planar shape (that is, a so-called fan beam) like a fan.

  In the present embodiment, as will be described below, the subject H held on the subject table 70 is conveyed on the support table 52 of the photographing table 50 in a certain direction (the direction of the arrow in FIG. 6). Therefore, when using the radiation source which irradiates a fan beam as mentioned above, a radiation is irradiated from a radiation source so that a fan beam may spread in the said fixed direction.

  On the other hand, in the present embodiment, a subject table 70 that holds the subject H is arranged on the support table 52 of the imaging table 50 constituting the radiation tomography apparatus 1, and the subject table 70 is moved in a predetermined direction. A transfer device 71 is provided.

  The subject table 70 is made of a resin plate such as an acrylic plate, a plate made of an inorganic material such as a carbon plate, or a metal plate. Further, it has a rigidity that does not bend or extend even if it is pushed or pulled by the conveying device 71 and moved in a predetermined direction while holding the subject H above it, and absorbs radiation. It is made of a material with a low rate.

  Note that, for example, a handrail (not shown) is provided on the side of the subject table 70 where the subject H is lying, so that the patient who is the subject H can hold and maintain the posture. Is also possible.

  Although not shown, the transport device 71 includes, for example, a drive motor and the like, and is configured to transmit the rotational force of the drive motor to the subject table 70 with a rack and pinion to move the subject table 70 in the horizontal direction. .

  The transport device 71 can adopt any configuration, mechanism, or the like as long as the subject table 70 can appropriately transport the object table 70 on the support table 52 of the imaging table 50 in the horizontal direction. However, the present invention is not limited to the configuration using the above rack and pinion. For example, a linear motion of an actuator or the like can be transmitted to the subject table 70 to move the subject table 70.

  In the case of the radiation tomography apparatus 1 shown in FIG. 6, the transport apparatus 71 holds the object table 70 on the object table 70 by moving the object table 70 in the horizontal direction (see the arrow in FIG. 6). The subject H is moved in the horizontal direction.

  In this case, since the extending direction of the surface 4a of the substrate 4 of the radiation detector F is arranged in the horizontal direction as described above, the transport device 71 removes the subject held on the subject table 70. The radiation detector F is configured to move in a direction parallel to the extending direction of the surface 4a of the substrate 4 of the radiation detector F.

  Then, while the subject H moves in the horizontal direction together with the subject table 70 as described above, tomosynthesis imaging is performed a predetermined number of times, and the projection image S is acquired by the radiation detector F as described above for each imaging. Configured to be

  At that time, for example, the radiation source 61 continuously irradiates the subject H, the radiation detector F, and the like without interruption, and the radiation detector F performs a predetermined number of times of acquiring the projection image S during that time. Is possible. Alternatively, the radiation source 52 may be irradiated with a predetermined number of times (pulse irradiation), and the projection image S may be acquired by the radiation detector F each time the radiation is irradiated.

  The radiation detector F may be configured to transmit the acquired projection image S to the console 90 as an image processing device via the control BOX 80 (see FIG. 6) every time the projection image S is acquired. Also, the acquired projection images S are temporarily stored in the storage means 23 (see FIG. 4), and the projection images S are collectively transmitted to the console 90 when the predetermined number of times of acquiring the projection images S is completed. It is also possible to configure so as to. In the case of adopting a method in which transmission is performed after completion of the photographing, the wired connection using the cable Ca described above is not essential.

  In the present embodiment, as shown in FIG. 7, a predetermined number of projections are performed while the subject H moves from the start position (for example, see position A in FIG. 7) to the end position (for example, see position B in FIG. 7). In order to perform the acquisition process of the image S, the speed at which the conveyance device 71 moves the subject table 70 is appropriately determined.

  In addition, in the reconfiguration described later, the relative position information between the radiation source 61 and the subject H is required. This may be provided with a means for detecting the position of the subject table 70, and the position information may be acquired in advance. If the set predetermined range is moved at a predetermined speed, position information set in advance can be used. Furthermore, when the radiation detector F is configured to move in addition to the subject H, the relative position information of the radiation detector F is required in the same manner. This is provided with means for detecting the position of the radiation detector F. The position information may be acquired, or a predetermined range set in advance may be moved at a predetermined speed, and the preset position information may be used.

  Further, as described above, when the radiation source 61 is configured to emit radiation a predetermined number of times, the conveyance device 71 moves the subject table 70 and the radiation irradiation device 60 emits radiation from the radiation source 61. The timing (that is, the irradiation interval of radiation) and the like to be determined are appropriately adjusted and determined.

  For example, in the present embodiment, when a 17 × 17 inch radiation detector F is used, one side of the radiation incident surface R (see FIG. 5 etc.) of the radiation detector F is about 42 cm. The moving distance of the subject H from the start position A to the end position B is set to 35 cm, for example.

  If the projection image S is acquired every time the subject H moves 7 mm together with the subject table 70, the projection image S acquisition processing can be performed 51 times while the subject H moves 35 cm. Thus, 51 projection images S are acquired by the radiation detector F.

  This can be acquired, for example, by setting the frame rate at the time of imaging by the radiation detector F to 7.5 fps and the moving speed of the subject H to 52.5 mm / sec. The combination of the number of projection images S, the moving speed of the subject H, and the frame rate at the time of photographing with the radiation detector F is not limited to this, and for example, the moving speed of the subject H is limited to 30 mm / sec. Alternatively, 88 projection images S may be acquired by setting the frame rate at the time of photographing with the radiation detector F to 7.5 fps.

  Note that if the console 90 is configured to adjust the speed and the like and adjust the speed and frame rate in this way, the radiographer or other radiographer will be more convenient.

  Further, when radiation is emitted from the radiation source 61, the conveyance of the subject table 70 by the conveyance device 71 is stopped, and the radiation is emitted in a state where the subject H is stopped (that is, in a state where it is not moving). It is also possible.

  However, with such a configuration, when the conveyance of the subject table 70 by the conveyance device 71 is stopped and the movement of the subject H is stopped, the posture of the subject H is shaken (that is, the body of the patient who is the subject H shakes). Can be considered. Therefore, in the present embodiment, from the viewpoint of maintaining the posture of the subject H so as not to be shaken when starting and / or stopping, the transport device 71 transports the subject table 70 at a constant speed, and the subject H is at a constant speed. While moving, a predetermined number of times of obtaining the projection image S is performed.

  Note that by smoothly changing the speed at the start and end of movement of the subject table 70, the posture of the subject H is less likely to be shaken, and the subject can be moved safely.

  Further, the radiation source 61 can be configured to perform a swinging motion in accordance with the movement of the subject H (see FIG. 7 and the like). However, the position of the radiation source 61 is fixed and does not move in the horizontal direction or the vertical direction. This point will be described later.

  In the present embodiment, the position of the radiation detector F is also fixed because it is loaded in the loading unit 51 of the imaging stand 50. However, although not shown in the figure, for example, the radiation detector F is moved stepwise in the horizontal direction in the loading unit 51 of the imaging stand 50, or the radiation detector F is not loaded in the loading unit 51 and is horizontal. The radiation detector F is moved in the horizontal direction stepwise in accordance with the movement of the subject H. By configuring, it is possible to take an image that is larger than the imageable region of the radiation detector F (as if the image was taken using a radiation detector having a large-size imaged region).

  As is well known in the field of tomosynthesis imaging, if the view angle (that is, the angular range of radiation incident on the subject) is increased as an effect on the image quality of the reconstructed image, a false image peculiar to tomosynthesis, that is, CT Since the view angle is smaller, the phenomenon that objects in places other than the tomographic plane appear in the image is reduced. Further, if the number of acquired projection images S is increased, image noise is reduced. Therefore, anyway, it is preferable to use a large-sized radiation detector such as 17 × 17 inches as the radiation detector F because any of the above effects can be obtained.

  Further, in order to enable imaging of a large number of projection images S in which the subject H is relatively moved relative to the radiation source 61, for example, FIG. 8 shows the imaging table 50 of the radiation tomography apparatus 1 as viewed from above. As shown, the radiation detector F arranged in the horizontal direction (that is, arranged with the radiation incident surface R facing upward) is arranged with its side surface inclined by 45 ° with respect to the body axis of the subject H. Then, as shown in FIG. 8, the region of interest of the subject H can be configured to move in the diagonal direction of the radiation incident surface R of the radiation detector F.

  With this configuration, for example, in the case of a square radiation detector F such as 17 × 17 inches, the side surface of the radiation detector F is parallel to the body axis of the subject H as shown in FIG. The distance from the start position A to which the subject H is moved to the end position B (see FIG. 7) can be increased by √2 times, that is, about 1.4 times longer than the case where the radiation source 61 is moved. On the other hand, the moving distance for moving the subject H relatively can be increased.

  The above configuration is preferable because the number of projection images S necessary for maintaining a predetermined resolution (the number of photographing) can be secured for the start position A and end position B in the moving direction of the subject H. . Of course, since the number of projection images S can be increased more in the center of the moving direction of the subject, it is possible to obtain effects such as reduction of false images peculiar to tomosynthesis and reduction of image noise as described above. It becomes possible.

[Image processing device]
In the present embodiment, as described above, the console 90 also functions as an image processing apparatus. However, the image processing apparatus may be configured as a separate device from the console 90. Hereinafter, the console 90 as an image processing apparatus is simply referred to as an image processing apparatus 90.

  In the present embodiment, the image processing apparatus 90 receives the projection image S acquired from the radiation detector F of the radiation tomography apparatus 1 as described above from the cable Ca (see FIG. 5) and the control BOX 80 (see FIG. 1). ) Or the like, or when transmitted wirelessly via the access point 95 or the like, the projection image S is reconstructed to generate a two-dimensional or three-dimensional tomographic image of the subject. It is supposed to be.

  At this time, in this embodiment, the image processing apparatus 90 reconstructs the transmitted projection image S to generate a coronal image as shown in FIGS. 9A and 9B. However, as described in, for example, Patent Documents 1 and 2 described above, an axial image (transverse image) that is a tomographic image cut along a plane orthogonal to the body axis using the projection image S, and a human body In principle, it is also possible to reconstruct a sagittal image (sagittal image) which is a tomographic image cut so as to be divided into two.

  However, in this case, the resolution of the reconstructed image is greatly reduced as compared with the coronal image. As a countermeasure, the reduction in resolution is improved by increasing the incident angle range of the radiation to the subject (that is, the movement distance of the human body in the apparatus configuration of this embodiment). In addition, by generating a tomographic image in which the angle of the tomographic plane is slightly changed (for example, in the range of the incident angle of radiation) with respect to the coronal image, it is possible to obtain a tomographic image in which the angle is changed while suppressing a decrease in resolution. .

[Action]
Hereinafter, the operation of the radiation tomography apparatus 1 according to the present embodiment and the radiation tomography system 100 using the same will be described.

  For example, in the radiation tomography apparatus described in Patent Documents 1 and 2 described above, a rotating table is provided between a radiation source whose position is fixed and a radiation detector, and the patient is erected on the rotating table, and the rotating table is rotated. To rotate the patient's body as a subject. In this manner, the radiation source and the subject are relatively moved, and in this case, the projection image S is obtained by rotating around the body axis of the patient as the subject. In the subsequent image processing, the acquired projection image S was reconstructed to generate a tomographic image in the body thickness direction of the patient.

  However, as described above, in such a radiation tomography apparatus, there is a case where a patient as a subject cannot stand on the turntable or it is difficult to maintain the same posture even if the patient can stand up. In such a case, it may be difficult or impossible to shoot.

  However, in the radiation tomography apparatus 1 and the radiation tomography system 100 according to the present embodiment, the patient who is the subject H may lie on the subject table 70 as described above. The subject H is moved in the horizontal direction together with the subject table 70 when the subject table 70 is moved in the horizontal direction by the transport device 71.

  Therefore, the patient who is the subject H can automatically form a state in which the subject H and the radiation source 61 are relatively moved only by lying on the subject table 70. Therefore, as described above, even when the patient who is the subject H cannot stand up or it is difficult to maintain the standing posture, the tomosynthesis is simply lying on the subject table 70. Shooting can be performed.

  Then, the image processing apparatus 90 can reconstruct the projection image S photographed as described above to accurately generate a two-dimensional or three-dimensional tomographic image.

  In the present embodiment, as described above, radiation tomography is performed by using the radiation irradiation device 60 and the imaging table 50 that are already installed in a facility such as a hospital, and adding the subject table 70 and the transport device 71 to the radiation irradiation device 60. The apparatus 1 can be configured.

  As described above, in this embodiment, since the introduction cost of the radiation tomography apparatus 1 is only required for the newly introduced subject table 70, the transport apparatus 71, and the like, the radiation tomography apparatus 1 for facilities such as hospitals is used. It is possible to introduce the radiation tomography apparatus 1 and the radiation tomography system 100 at a low cost by accurately suppressing an increase in the introduction cost of the radiation tomography system 100.

  As a configuration that may be similar to the present embodiment, for example, in Japanese Patent No. 3926574 and Japanese Patent Application Laid-Open No. 2013-31641, a subject is laid down on a shooting table for lying position shooting, and the subject moves. A radiation tomography apparatus that performs tomosynthesis imaging by moving a radiation source or the like without moving the subject and the radiation source relative to each other is described.

  However, in such a configuration, at least the radiation source is moved, and the radiation irradiation apparatus including the radiation source is modified. Therefore, there is a possibility that the radiation tomography apparatus cannot be easily introduced into the facility, for example, because it may be necessary to obtain a new approval based on the Pharmaceutical Affairs Law for the modified radiation irradiation apparatus.

  In contrast, in the present embodiment, at least the radiation source 61 is not moved, and the radiation tomography apparatus 1 is changed without changing the state in which the position is fixed (that is, the state approved by the Pharmaceutical Affairs Law). Since it becomes possible to configure, the radiation tomography apparatus 1 configured as described above need not be re-approved under the Pharmaceutical Affairs Law.

  Therefore, there is an advantage that the radiation tomography apparatus 1 and the radiation tomography system 100 using the radiation tomography apparatus 1 can be easily introduced into the facility.

[effect]
As described above, according to the radiation tomography apparatus 1 and the radiation tomography system 100 according to the present embodiment, the subject H held on the subject table 70 is moved by moving the subject table 70 in the horizontal direction by the transport device 71. Are moved in the horizontal direction between the radiation source 61 and the radiation detector F whose positions are fixed, or at least below the radiation source 61 whose positions are fixed. The radiation detector F is configured to perform a predetermined number of times of obtaining the projection image S while the transport device 71 moves the subject table 70 and moves the subject H.

  Therefore, the patient who is the subject H is automatically held in the subject table 70 and moves horizontally below the radiation source 61 just by lying on the subject table 70. Of course, it is possible to acquire the projection image S automatically by moving the subject H and the radiation source 61 relative to a patient or the like who is difficult to stand up. It is possible to perform tomosynthesis imaging.

  Further, in the radiation tomography apparatus 1 and the radiation tomography system 100 according to the present embodiment, the radiation source 61 already installed in the facility, the radiation irradiation apparatus 60 including the radiation source 60, the imaging table 50, etc. are used, and they themselves. Therefore, the radiation tomography apparatus 1 can be configured without any modification.

  Thus, it becomes possible to configure the radiation tomography apparatus 1 using facilities such as the existing radiation irradiation apparatus 60 and the imaging table 50 in a facility such as a hospital, and the introduction cost of the radiation tomography apparatus 1 is newly increased. Since only the object table 70 and the conveyance device 71 to be introduced are required, the introduction of the radiation tomography apparatus 1 and the radiation tomography system 100 to the facility is accurately suppressed, and the radiation tomography apparatus is accurately controlled. 1 and the radiation tomography system 100 can be introduced into the facility at a low cost.

  Then, it is possible to generate a coronal image (a coronal cut image) using existing equipment.

[Modification 1]
In the above-described embodiment, the radiation tomography apparatus is used as the imaging table 50 using an imaging table for supine imaging, that is, a type of imaging table in which the patient who is the subject H lies on the support table 52 and performs imaging. 1 has been described. However, for example, the radiation tomography apparatus 1 can be configured using an imaging stand for standing imaging. This will be specifically described below.

  In this case, for example, as shown in FIG. 10, between the radiation source 61 whose position is fixed and the radiation detector F which is loaded in the loading unit 51 of the imaging stand 50 for standing imaging and whose position is fixed. A subject table 70 that holds the subject H in an upright state, and a transport device 71 that moves the subject table 70 in a predetermined direction, that is, a vertical direction in this case, are provided.

  In this case, for example, as shown in FIG. 10, the support column 72 is erected in a vertical direction from the floor surface at a position where radiation is not shielded, and the object table 70 is guided by the support column 72 to move in the vertical direction. It is possible to configure so that. In addition, when the subject H is a person, the subject table 70 can be configured to have only a portion in contact with the foot. Even in the configuration of only the portion in contact with the foot, the subject H can be held, and it is possible to use a so-called electric elevating stepping platform or electric elevating photographing table.

  In this case, in the radiation detector F, the surface 4a (see FIG. 3) of the substrate 4 on which the plurality of radiation detection elements 7 are arranged is perpendicular to the floor surface on which the radiation tomography apparatus 1 is installed. Will be placed in the state. That is, the extending direction of the surface 4a of the substrate 4 of the radiation detector F is oriented in the vertical direction.

  Then, the transport device 71 moves the subject table 70 in the vertical direction to move the subject H held on the subject table 70 in the vertical direction, and while the subject H moves in the vertical direction, the above-described embodiment. In the same manner as described above, the projection image S is acquired a predetermined number of times.

  In this case, as shown in FIG. 10, it may be configured such that the projection image S is acquired a predetermined number of times while moving the subject H upward, and the predetermined amount while moving the subject H downward. It is also possible to configure so that the number of times of obtaining the projection image S is performed. Further, the subject H is configured to perform a predetermined number of times of acquiring the projection image S while moving the patient who is the subject H in the horizontal direction from the near side to the far side or from the far side to the near side in the figure. Is also possible.

  On the other hand, for example, even when a large radiation detector F such as 17 × 17 inches cannot be used, for example, the imaging stand 50 for standing imaging moves the loading unit 51 up and down to move the radiation detector F in the vertical direction. As long as it can be moved, as shown in FIG. 11, it is also possible to perform tomosynthesis imaging by moving the radiation detector F continuously or stepwise as the subject H moves. It is.

  If the radiation detector F can be mounted on the subject table 70 and moved together with the subject H, it is not necessary to separately provide a moving means for the radiation detector F, or the subject H and the radiation detector F This makes it unnecessary to synchronize the movement position.

  In this case, for example, as shown in FIG. 11, it is desirable to provide a cover plate unit 75 between the radiation source 61 and the subject H.

  For example, as shown in FIG. 12, the cover plate unit 75 is configured to include a cover plate 75 a that limits an irradiation region of the radiation irradiated from the radiation source 61. The cover plate 75a is fixed to the floor surface by a pedestal 75b, and is supported by a guide shaft 75c that supports the cover plate 75a so as to be movable up and down. For example, it is configured to be able to move in the vertical direction by driving a drive motor (not shown).

  The cover plate 75a is provided with an opening W having a predetermined size. Of the radiation irradiated from the radiation source 61, the radiation that has passed through the opening W without being blocked by the cover plate 75a is just detected by radiation. The size of the opening W is adjusted so that the device F is irradiated. Then, by moving the cover plate 75 a in the vertical direction in accordance with the movement of the radiation detector F, the radiation detector F is adjusted so that the radiation passing through the opening W is accurately irradiated to the radiation detector F.

  With this configuration, the radiation that has passed through the subject H is reliably incident on the radiation detector F. Therefore, it is possible to prevent the patient's body that is the subject H from being irradiated with radiation over a wide range and the patient's exposure dose from increasing. The cover plate unit 75 can be configured integrally with the radiation source 61 or can be configured integrally with the subject table 70.

  Also, as shown in FIGS. 10 and 11 and the like, when configured to perform tomosynthesis imaging while moving the subject table 70 in the vertical direction and moving the subject H in the vertical direction, for example, the patient stands up. Even if it is difficult, the subject H is moved in the vertical direction while being held on the subject table 70 by, for example, fixing the patient's body to the subject table 70 with a restraint (not shown) or the like. Thus, it is possible to perform tomosynthesis imaging accurately as in the case of the present embodiment.

Also in this modified example, the radiation source 61 already installed in a facility such as a hospital, the radiation irradiation apparatus 60 including the radiation source 61, the imaging stand 50 for standing-up imaging, etc. are used, and any modifications are made in themselves. It is possible to configure the radiation tomography apparatus 1 ^* without adding.

Thus, it becomes possible to configure the radiation tomography apparatus 1 ^* using facilities such as the existing radiation irradiation apparatus 60 and the imaging table 50 in a facility such as a hospital, and the introduction cost of the radiation tomography apparatus 1 ^* . However, since only the newly introduced subject table 70 and transport device 71 are required, the introduction cost of the radiation tomography apparatus 1 ^* and the radiation tomography system 100 ^* using the same to the facility will rise. With appropriate suppression, the radiation tomography apparatus 1 ^* and the radiation tomography system 100 ^* can be introduced into the facility at a low cost.

[Modification 2]
In addition, for example, when the imaging table 50 that is already installed in a facility such as a hospital is an imaging table that can orient the direction of the support table 52 in an oblique direction with respect to the floor, not in the horizontal or vertical direction. Unlike the above-described embodiment and Modification 1, it is also possible to perform tomosynthesis imaging with the support base 52 of the imaging base 50 directed in an oblique direction.

  In this case, for example, the subject table 70 is configured to move on the surface of the support table 52 facing in an oblique direction, and the patient who is the subject H is held on the subject table 70 while facing the diagonally upward direction. It can be configured to move with the base 70. In this configuration, it goes without saying that the substrate surface of the radiation detector F and the moving direction of the subject H are parallel.

  And even if comprised in this way, it becomes possible to acquire the same beneficial effect as the case of said embodiment and the modification 1. FIG.

  Needless to say, the present invention is not limited to the above-described embodiments and modifications, and can be appropriately changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Radiation tomography apparatus 4 Board | substrate 4a Surface (surface)
7 Radiation Detection Element 61 Radiation Source 70 Subject Base 71 Conveying Device 90 Console (Image Processing Device)
100 Radiation Tomography System F Radiation Detector H Subject S Projected Image

Claims (5)

A plurality of radiation detectors arranged two-dimensionally on one surface of the substrate, a radiation detector that converts the irradiated radiation into an electric charge and obtains it as a projection image;
A radiation source that irradiates the radiation detector with radiation through a subject;
A subject table for holding the subject;
A transfer device for moving the subject table in a predetermined direction;
With
The transfer device moves the subject table to move the subject held on the subject table between the radiation detector and the radiation source whose position is fixed, on the substrate of the radiation detector. Move in a direction parallel to the direction of the surface extension,
The radiation detector is a radiation tomography apparatus characterized in that the transport device moves the subject table and performs the projection image acquisition process a predetermined number of times at different positions of the subject.   The radiation tomography apparatus according to claim 1, wherein the radiation detector is arranged such that the surface of the substrate is parallel to a floor surface on which the apparatus is installed.   The radiation tomography apparatus according to claim 1, wherein the radiation detector is arranged such that the surface of the substrate is perpendicular to a floor surface on which the apparatus is installed.   The position of the radiation detector is not fixed, and the radiation detector is configured to move in a direction parallel to the extending direction of the surface of the substrate in accordance with the movement of the subject. The radiation tomography apparatus according to any one of claims 1 to 3. Radiation tomography apparatus according to any one of claims 1 to 4,
An image processing apparatus for reconstructing the projection image acquired by the radiation detector to generate a tomographic image of a subject;
A radiation tomography system comprising:

Images