JP2012065768A - Portable radiation imaging system, holder used therein, and portable set for radiation imaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve various key problems of a portable X-ray imaging system simultaneously.SOLUTION: The X-ray imaging system 2 includes two X-ray sources 10a, 10b. The X-ray sources 10a, 10b are mounted on the rails 27a, 27b of a cross bar 23 of a holder 14 by connectors 25a, 25b. The X-ray sources 10a, 10b can be moved along the rails 27a, 27b by shift mechanisms 28a, 28b. The X-ray source 10a is used for imaging from one end to the center of the cross bar 23 and the X-ray source 10b is used for imaging from the center to the other end. An imaging control device 12 controls the drive of the X-ray sources 10a, 10b and the shift mechanisms 28a, 28b so that the X-ray sources 10a, 10b repeat imaging and shift alternately (while one of the X-ray sources 10a, 10b is shifted, the other performs imaging).

Description

  The present invention relates to a portable radiographic imaging system that performs imaging by moving a radiation source, a holder used therefor, and a portable radiographic imaging set.

  In order to observe the region of interest (ROI) of the subject in more detail, the subject is irradiated with X-rays from different angles while moving a radiation source, for example, an X-ray source (X-ray tube), and the obtained images are added. Then, tomosynthesis imaging for obtaining a tomographic image in which a desired tomographic plane is emphasized is known (see Patent Document 1).

  Patent Document 1 discloses a portable X-ray imaging system suitable for emergency medical treatment in the event of an accident or disaster. The system consists of a set of an X-ray source, an X-ray source holder, an X-ray detector, a power supply device, a control device and a transport device. Carry another set to the shooting site with the transport device, assemble the system at the site and perform tomosynthesis shooting. Patent Document 1 describes an aspect in which one X-ray source is moved and an aspect in which an array in which a plurality of X-ray sources are arranged is used.

JP 2008-253762 A

  In a portable X-ray imaging system such as Patent Document 1, it is important not to spend much time on imaging in consideration of quickness in emergency medical treatment and burden on a patient who is physically inconvenient at home. . In addition, it is important that the system is less mobile than the stationary system that is not portable, and has the mobility required to transport and install the system.

  In an embodiment in which one X-ray source is moved as an example of Patent Document 1, movement and imaging must be repeated 40 to 80 times with one X-ray source to complete one set of tomosynthesis imaging, and time Too much.

  In the embodiment using one array, the imaging time is shortened because the X-ray source is not moved, but instead 40 to 80 X-ray sources need to be prepared, and the X-ray source becomes large and heavy. Furthermore, if the X-ray source is heavy, the support that supports it must also be made robust, resulting in a very heavy system as a whole, which hinders the transportation and installation of the system, resulting in poor mobility. turn into. Also, preparing 40 to 80 X-ray sources is impractical for use in a portable X-ray imaging system from a cost standpoint. In the aspect using the array, the imaging time can be shortened, but in addition to satisfying all the important issues of the portable X-ray imaging system of ensuring the mobility of the system and providing an inexpensive system. It does n’t come.

  The present invention has been made in view of the above problems, and its purpose is to simultaneously solve the important problems of a portable X-ray imaging system, such as shortening of imaging time, ensuring the mobility of the system, and providing an inexpensive system. There is to clear.

  In order to achieve the above object, a portable radiographic imaging system of the present invention includes n radiation sources that irradiate a subject and radiation image detection that detects an image by receiving radiation transmitted through the subject. And a holder for movably supporting the n radiation sources with respect to the radiation image detector, so that radiation can be emitted from the n radiation sources at different angles with respect to the radiation image detector. And a moving mechanism for moving the n radiation sources to N (N >> n) positions on the holder.

  It is preferable to include an image generation device that generates a tomographic image in which the region of interest of the subject is emphasized based on the N pieces of image data output from the radiation image detector.

  Each of the n radiation sources is moved to approximately N / n positions that do not overlap each other by the moving mechanism, and irradiates the radiation at timings that do not overlap each other. Each of the n radiation sources is responsible for irradiation of radiation in a range obtained by dividing the entire moving range by the moving mechanism into n equal parts.

  The moving mechanism moves another radiation source to the next position when one of the n radiation sources emits radiation. The n radiation sources may be simultaneously moved and stopped at the next position. You may provide the operation input means to select these two drive patterns.

  The moving mechanism moves the n radiation sources in a direction to cancel each other's vibrations accompanying the movement. In this case, it is preferable that n is an even number, and the n radiation sources move in symmetrical positions on the holder.

  The image generation apparatus stores an identifier indicating the position of the radiation source and image data in association with each other.

  It is preferable that the holder has a curved trajectory such that the radiation source faces the radiation image detector at each position. N is preferably 2.

  The radiation source has a fixed anode radiation tube. The radiation source has a radiation tube using a cold cathode electron source.

  The portable radiographic image capturing set of the present invention includes a radiographic image detector that detects an image by receiving radiation transmitted through a subject, and n radiation sources that irradiate the subject with radiation to the radiographic image detector. A holder that is movably supported with respect to the radiation image detector and N positions (N >> n) on the holder so that radiation can be emitted from the n radiation sources at different angles with respect to the radiation image detector. And a moving mechanism for moving the n radiation sources.

  The holder used in the portable radiographic imaging system of the present invention includes a support unit for supporting n radiation sources for irradiating a subject with radiation, and a radiographic image detection for detecting an image by receiving radiation transmitted through the subject. And a moving mechanism for moving the support to N (N >> n) positions so that radiation can be emitted from a radiation source at different angles with respect to the vessel.

  According to the present invention, radiation is irradiated while moving n radiation sources, and N times (N >> n) imaging is shared by the n radiation sources, so that the imaging time is shortened and the mobility of the system is increased. The important problem of the portable X-ray imaging system of securing and providing an inexpensive system can be cleared at the same time.

1 is a perspective view showing a schematic configuration of an X-ray imaging system. It is a figure which shows schematic structure of an X-ray tube. It is a timing chart which shows the operation state of each X-ray source which concerns on 1st embodiment, (A) is the case where one imaging time and movement time are substantially the same, (B) is the case where imaging time is shorter than movement time Respectively. It is a block diagram which shows the electrical structure of an imaging | photography control apparatus. It is a figure for demonstrating the specific example which attaches | subjects the identifier which shows an imaging | photography position to image data. It is a schematic diagram which shows the process sequence of tomosynthesis imaging | photography. It is a figure which shows a mode that the whole was covered with the X-ray shielding sheet, (A) shows the state seen from the body side surface of the subject, (B) shows the state seen from the head direction of the subject. It is a perspective view which shows the example which provided the winding part of the cable. It is a timing chart which shows the operation state of each X-ray source concerning a second embodiment.

[First embodiment]
In FIG. 1, an X-ray imaging system 2 detects two X-ray sources 10a and 10b that irradiate X-rays, and X-rays that have been irradiated from the X-ray sources 10a and 10b and transmitted through a subject P. A cassette 11 for outputting data, an X-ray source 10a, 10b, an X-ray control device 12 for controlling the X-ray imaging operation, and an X-ray tube 18a of the X-ray source 10a, 10b for the X-ray source 10a, 10b. , 18b tube voltage, tube current, exposure time, etc.) and a holder 14 holding the X-ray sources 10a, 10b.

  The X-ray sources 10a and 10b, the cassette 11, the imaging control device 12, the console 13, and the holder 14 are all portable. These can be carried to the site where emergency medical treatment such as an accident or disaster is necessary, or to the home of a patient receiving home medical care, and X-ray imaging can be performed.

  In addition, since each part of X-ray sources 10a and 10b, X-ray tubes 18a and 18b which comprise these, and each part of the moving mechanisms 28a and 27b related to these are the same structures, unless it is necessary to distinguish below, Each part related to the X-ray source 10a will be described, and each part related to the X-ray source 10b will be denoted by a reference numeral, and description thereof will be omitted.

  The imaging control device 12 gives an operation command to the X-ray source 10a and the cassette 11 so that the respective operation timings are synchronized based on the imaging conditions input from the input device 15 of the console 13. When receiving an exposure instruction signal from the irradiation switch 29, the imaging control device 12 notifies the cassette 11 to that effect, thereby performing synchronous control of the operations of the X-ray source 10 a and the cassette 11.

  The image data output from the cassette 11 is input to the console 13 via the imaging control device 12. The console 13 includes a personal computer and a workstation, and performs various image processing on the received image data, displays an image on the display 16, and uploads the image data to an external data storage device such as an image storage server.

  The X-ray source 10 a is connected to the imaging control device 12 by a cable 17 and is supplied with power from the imaging control device 12. The X-ray source 10a includes an X-ray tube 18a that generates X-rays by a high voltage from a driver 41a (a high-voltage generator, see FIG. 4), and a collimator that regulates an X-ray irradiation field generated by the X-ray tube 18a. (Irradiation field limiter, not shown).

  In FIG. 2, an X-ray tube 18a is a fixed anode X-ray tube having no target rotation mechanism. The X-ray tube 18a includes a cold cathode electron source 30a that emits electrons, an electron accelerator 31a, a target 32a that generates X-rays by collision of electrons, and an outer tube 33a that accommodates these. The cold cathode electron source 30a does not require a filament and a heater for heating the filament as in the case of a hot cathode.

  Since the X-ray tube 18a does not have a target rotation mechanism, and does not have a filament and a heater, it is small and light. Further, since no residual heat of the filament is required, X-ray irradiation can be performed in response to an imaging instruction. For this reason, there is an advantage that photographing can be performed immediately at the time of emergency medical treatment. The X-ray tube 18a includes, for example, an ultra-compact X-ray generator that can be accommodated in a coaxial cable of 2 mm or less, as described in Japanese Patent No. 3090910, and "" Development and application of a dry cell-driven micro-electron accelerator / high-energy X-ray source " March 29, 2009 Ryoichi Suzuki, National Institute of Advanced Industrial Science and Technology <http://beam-physics.kek.jp/bpc/suzuki.pdf> ”using an X-ray tube using carbon nanostructures it can. In the case of the latter X-ray tube, since it is driven by a dry battery, the X-ray source 10a and the imaging control device 12 may be cableless, and only an exposure instruction signal may be wirelessly communicated.

  Returning to FIG. 1, the cassette 11 has a substantially rectangular shape, is wired to the imaging control device 12 with a cable 19, and power is supplied from the imaging control device 12. The cassette 11 is placed under the subject P with the image receiving surface 20 facing the X-ray sources 10a and 10b as shown in the figure, and is appropriately positioned at a position corresponding to the imaging region such as a shoulder or a knee. A handle 21 is provided on one side of the cassette 11 for convenience of carrying. Although not shown, the X-ray sources 10a and 10b other than the cassette 11 and the imaging control device 12 also have a handle for carrying.

  The cassette 11 includes an X-ray detection unit 44 (see FIG. 4). The X-ray detection unit 44 is, for example, a flat panel detector (FPD) having a matrix substrate in which a plurality of pixels including thin film transistors (TFTs) and X-ray detection elements are two-dimensionally arranged. The X-ray detection unit 44 accumulates charges according to the amount of X-rays incident when the TFT is turned off by the X-ray detection element. Then, the TFT is turned on to read out the charge accumulated in the X-ray detection element. The read charge is converted into a voltage signal by an integrating amplifier of the signal processing unit 45 (see FIG. 4), and the converted voltage signal is A / D converted by an A / D converter of the signal processing unit 45, thereby obtaining a digital image. Data is generated.

  The holder 14 has two sets of support legs 22 that are open at a predetermined angle and are erected on the floor or the ground, and a horizontal bar 23 that is bent in an arc shape. The upper end of the support leg 22 and both ends of the horizontal bar 23 are connected to a trifurcated joint 24, whereby the holder 14 is assembled. The assembled holder 14 is symmetrical about the center of the horizontal bar 23 as an axis. Connectors 25a and 25b for connecting the X-ray sources 10a and 10b electrically and mechanically are attached to the horizontal bar 23, respectively. The cable 17 is connected to the connector 25b.

  The connectors 25a and 25b are further connected to each other by a cable 26, and the X-ray source 10b is connected to the imaging control device 12 by cables 17 and 26 similarly to the X-ray source 10a, and power is supplied from the imaging control device 12. The The cable 26 is bent to such an extent that the X-ray sources 10a and 10b do not become taut when the X-ray sources 10a and 10b move to both ends of the horizontal bar 23. Alternatively, the cable 26 is formed of a stretchable material. The X-ray sources 10a and 10b are electrically connected to the cables 17 and 26 by being attached to the connectors 25a and 25b, and are hung on the horizontal bar 23. The X-ray sources 10a and 10b are exposed to X-rays in a substantially vertical direction while being hung on the horizontal bar 23.

  The connector 25a is fitted to a groove-like rail 27a formed in the lower part of the horizontal bar 23 in parallel with the longitudinal direction of the horizontal bar 23, and can be moved along the rail 27a by the moving mechanism 28a. The rail 27b into which the connector 25b is fitted is formed in the upper part of the horizontal bar 23 facing the rail 27a, and the rails 27a and 27b slightly overlap at the center position of the horizontal bar 23. Since the rails 27a and 27b are overlapped, one of the X-ray sources 10a and 10b is retracted to the end side of the horizontal bar 23 and the other is arranged at the central position of the horizontal bar 23, and imaging is performed at the central position. It is possible.

  The moving mechanism 28a incorporates a drive source 48a (see FIG. 4) such as a stepping motor that is driven based on a command from the imaging control device 12. When the drive source 48a is driven, the connector 25a, and hence the X-ray source 10a attached to the connector 25a, moves along the rail 27a. When the drive source 48a stops driving, the X-ray source 10 is brought to a desired position of the horizontal bar 23. Stop. The imaging control device 12 counts drive voltage pulses (pulses applied to the stepping motor) emitted to the drive source 48a, and detects the position of the X-ray source 10a on the horizontal bar 23 based on the counted number.

  In this example, the X-ray sources 10a and 10b are moved along the rails 27a and 27b of the arc-shaped horizontal bar 23. However, a straight horizontal bar is used, and X-rays are not generated along a curved track. The sources 10a and 10b may be moved. When a linear track is employed, a neck swing mechanism may be provided on the connectors 25a and 25b so that the X-ray sources 10a and 10b are directed to the cassette 11. In the curved trajectory as in this example, the X-ray sources 10a and 10b naturally face the cassette 11, so that it is not necessary to provide a neck swing mechanism.

  The imaging control device 12 controls the driving of the driving sources 48a and 48b, and sets the X-ray sources 10a and 10b at a plurality of equally spaced positions (for example, 40 to 80 locations) of the horizontal bar 23 set in advance according to imaging conditions. Move. The X-ray source 10a moves from the left end of the horizontal bar 23 in FIG. 1 to the center, and the X-ray source 10b moves from the right end of the horizontal bar 23 to the center. Assuming that the total stop position (number of times of imaging) determined by the imaging conditions is N, the X-ray sources 10a and 10b stop half of that time N / 2 times and take charge of N / 2 times of imaging. Further, at the time of photographing, these move from both ends of the horizontal bar 23 toward the center. That is, the X-ray sources 10a and 10b move at equal distances in opposite directions with the center of the horizontal bar 23 as the axis of symmetry.

  The imaging control device 12 irradiates the subject P with X-rays from the X-ray sources 10a and 10b each time the X-ray sources 10a and 10b reach the respective positions, and detects the X-rays with the cassette 11 each time. . By doing so, a plurality of image data detected by irradiating X-rays from different directions by changing a plurality of positions of the X-ray sources 10 a and 10 b are output from the cassette 11.

  As shown in the timing chart of FIG. 3, the imaging control device 12 alternately repeats imaging and movement of the X-ray sources 10a and 10b (while one of the X-ray sources 10a and 10b is moving, the other is imaging). The X-ray sources 10a and 10b and the movement mechanisms 28a and 28b are controlled.

  (A) shows the case where the shooting time for one time and the movement time are substantially the same, and (B) shows the case where the shooting time is shorter than the movement time. In (B), there is a period in which the X-ray sources 10a and 10b move simultaneously. In both cases (A) and (B), the time required for all imaging is halved compared to the case of using one X-ray source. Although not shown, the time required for the imaging preparation process of the X-ray detection unit 44 of the cassette 11 is included between each imaging.

  In FIG. 4, an X-ray source control unit 40a of the imaging control apparatus 12 controls the operation of each unit of the X-ray source 10a in an integrated manner. The X-ray source control unit 40a controls the operation of the X-ray tube 18a via the driver 41a, and operates the X-ray tube 18a with designated imaging conditions and operation timing.

  The cassette control unit 42 comprehensively controls the operation of each unit of the cassette 11. The cassette control unit 42 controls the operation of the X-ray detection unit 44 of the cassette 11 via the driver 43, and operates the X-ray detection unit 44 at a specified operation timing. Further, the cassette control unit 42 receives image data from the signal processing unit 45 having an integration amplifier and an A / D converter, and passes it to the console 13.

  The console 13 attaches an appropriate identifier indicating the shooting position to the image data transmitted from the cassette control unit 42 and stores the image data in a memory or a storage device. Specifically, as shown in FIG. 5, 1, 2, 3,..., N / 2, (in order from the left end of FIG. 1 with respect to the stop position of the horizontal bar 23 of the X-ray sources 10a and 10b. N / 2) +1,..., N−1, N (N is the total number of times of shooting determined by shooting conditions) are given for convenience. As described above, the X-ray source 10a is in charge of imaging of numbers 1 to N / 2, and moves according to the numbers to perform imaging. On the other hand, the X-ray source 10b is in charge of radiographing of numbers (N / 2) +1 to N, and moves in the opposite direction to the X-ray source 10a. Move to (N / 2) +1 and take a picture. The console 13 records the above number as an identifier in the file name and accompanying information of the image data from the cassette control unit 42, and distinguishes the shooting position of a series of image data by this identifier. For example, when the X-ray source 10a is imaged first, the X-ray source 10b is imaged next, and the X-ray sources 10a and 10b are imaged alternately, images sequentially sent from the cassette controller 42 are sent. An identifier such as 1, N, 2, N-1, 3, N-2, 4,.

  As schematically shown in FIG. 6, the console 13 is based on a plurality of image data output from the cassette 11 by changing a plurality of positions of the X-ray sources 10 a and 10 b and irradiating X-rays from different directions. A tomographic image of the subject P, in particular, a tomographic image (also referred to as a reconstructed image) parallel to the image receiving surface 20 of the cassette 11 in the region of interest ROI of the subject P is generated. At this time, the console 13 reads out the image data from the memory or the storage device in the order of the identifiers added at the time of taking in the image data, and executes image processing.

  As a method for generating a tomographic image, for example, a shift process for aligning the position of the ROI of each image is performed on image data captured and output at different positions a, b, c, d, and e, and then the shift process is performed. Each of the images is added to obtain a reconstructed image in which the ROI is emphasized.

  Other methods for generating a tomographic image include a simple backprojection method and a filtered backprojection method, which may be employed. The simple backprojection method is a method in which a plurality of images are backprojected as they are without applying a reconstruction filter to the plurality of images, and then subjected to addition processing to obtain a reconstructed image. On the other hand, in the filter back projection method, a reconstruction filter is applied to a plurality of images as a convolution filter, back projection is performed, and then addition processing is performed to obtain a reconstructed image. There is a method in which a reconstructed image is obtained by performing addition processing after applying a reconstruction filter to the data and backprojecting the data.

  Returning to FIG. 4, the movement mechanism control unit 46a controls the operation of the drive source 48a of the movement mechanism 28a via the driver 47a. The X-ray source control unit 40b and the moving mechanism 46b related to the X-ray source 10b have the same configuration and action. These control units 40a, 40b, 42, 46a, 46b cooperate to change a plurality of positions of the X-ray sources 10a, 10b and irradiate X-rays from different directions to obtain a plurality of image data. Each unit performs tomosynthesis imaging for generating a reconstructed image based on image data.

  As shown in FIGS. 7A and 7B, when taking an image with the X-ray imaging system 2, an X-ray shielding sheet 55 is attached to reduce the risk of exposure. (A) shows the state seen from the body side direction of the subject P, and (B) shows the state seen from the head direction of the subject P.

  The X-ray shielding sheet 55 contains an X-ray shielding material having high X-ray shielding properties such as lead, and is made of a flexible sheet-like material. The X-ray shielding sheet 55 has a size capable of covering the X-ray image capturing system 2 over substantially the whole. The X-ray shielding sheet 55 is attached to the joint 24, the horizontal bar 23, etc., and the X-ray shielding sheet 55 is hung down to the hem of the support leg 22 to cover the entire X-ray imaging system 2 including the region to be imaged of the subject P. . For attaching the X-ray shielding sheet 55, hooks, snaps, hook-and-loop fasteners, screwing, and the like can be used.

  At the top of the X-ray shielding sheet 55, a cable fixture 56 for fixing the cable 17 connecting the imaging control device 12 and the connector 25b in the middle is provided. The cable 17 is accommodated in the X-ray shielding sheet 55 in a state where the cable 17 is bent to a portion corresponding to the horizontal bar 23 of the holding tool 14 at the tip of the cable fixing tool 56. The cable 17 is bent to such an extent that the connector 25b does not tension even when the connector 25b moves from the center of the horizontal bar 23 to the right end along the rail 27b. The cable 17 expands and contracts with the cable fixture 56 as a fulcrum as the connector 25b moves.

  Next, the operation of the above configuration will be described. First, a radiographer using the X-ray imaging system 2 carries the X-ray imaging system 2 set to the imaging site, assembles the holder 14 as shown in FIG. 1, and attaches the connectors 25a and 25b and the X-ray sources 10a and 10b. Connect. Further, the cable 17 is connected to the connector 25b, the cable 19 is connected to the cassette 11, and the cable 26 is connected to the connectors 25a and 25b, so that the X-ray sources 10a and 10b and the cassette 11 are connected to the imaging control device 12.

  After the setting of the X-ray imaging system 2 is completed, the subject P is placed at a predetermined position where the X-ray sources 10a and 10b and the cassette 11 face each other, the X-ray shielding sheet 55 is attached, and the X-ray shielding sheet 55 is covered. The part to be imaged of the specimen P and the entire X-ray imaging system 2 are covered. Further, the middle of the cable 17 is fixed by the cable fixing tool 56, and the tip thereof is bent and accommodated in the X-ray shielding sheet 55.

  The radiologist inputs the imaging conditions and the like via the input device 15 of the console 13 and then presses the irradiation switch 29 attached to the imaging control device 12 to instruct the start of exposure. In response to an instruction to start exposure, the imaging control device 12 drives the drive sources 48a and 48b of the moving mechanisms 28a and 28b, and the X-ray sources 10a and 10b are moved to a plurality of preset positions of the horizontal bar 23. The Further, every time the X-ray sources 10a and 10b reach the respective positions under the control of the imaging control device 12, X-rays are irradiated from the X-ray tubes 18a and 18b of the X-ray sources 10a and 10b toward the subject P. X-rays are detected by the X-ray detection unit 44 of the cassette 11.

  More specifically, first, the drive sources 48a and 48b are driven to move the X-ray sources 10a and 10b to the initial positions (positions 1 and N in FIG. 5) at both ends of the horizontal bar 23. Then, the first imaging is performed first from the X-ray source 10a, and then the X-ray source 10b performs imaging. During imaging with the X-ray source 10b, the drive source 48a is driven to move the X-ray source 10a to the position of No. 2, which is the next imaging position. Immediately after the X-ray source 10b is imaged, the X-ray source 10a immediately proceeds to imaging at the position of number 2. In this way, imaging and movement are alternately repeated with the X-ray sources 10a and 10b to complete one set of tomosynthesis imaging.

  On the console 13, an identifier indicating the shooting position is attached to the plurality of image data obtained in this way. Then, the identifier is referred to generate a reconstructed image based on the plurality of image data. The generated reconstructed image is displayed on the display 16. The radiologist observes the reconstructed image displayed on the display 16 to make a diagnosis, or transmits the data of the reconstructed image to the telemedicine facility through the network, and instructs a specialist doctor residing at the telemedicine facility. Take appropriate measures such as

  As described above, according to the present invention, imaging is performed while moving the two X-ray sources 10a and 10b with respect to the cassette 11, so that the imaging time is significantly longer than when one X-ray source is used. It can be shortened. Since the X-ray sources 10a and 10b alternately repeat imaging and movement, it is possible to further reduce the imaging time. Moreover, compared with the case where the array which arranged the some X-ray source is used, component cost can be restrained cheaply.

  Emergency medical treatment may target suddenly ill people who are not easily braked due to pain, and some patients receiving home medical care have difficulty in maintaining the same posture, such as bedridden elderly people. It is particularly beneficial to shorten the shooting time and complete the shooting quickly because it increases the possibility of shooting a sick person or a bedridden elderly person without any trouble.

  In one set of tomosynthesis imaging, imaging is performed 40 to 80 times, but it is costly to construct an array with the same number of X-ray sources. In addition, the array becomes heavy and is not suitable for a portable X-ray imaging system. In this example, the number of X-ray sources 10a and 10b is at most two, and the X-ray tubes 18a and 18b are small and light. Therefore, they are not bulky during carrying and assembly, and the burden on the radiographer can be reduced. Since the X-ray tubes 18a and 18b are small and light, it is not necessary to make the component parts of the holder 14 so robust as compared with the case of using an array of X-ray sources that increase in weight. 14 can be simultaneously reduced in size and weight.

  Since the X-ray tubes 18a and 18b are small and light, vibrations associated with movement of the X-ray sources 10a and 10b are unlikely to occur. Therefore, it is not necessary to provide a vibration detection sensor to interrupt shooting until vibrations are reduced to some extent, or to take complicated measures such as correcting the image based on the vibration detection result, and shooting can be performed quickly. Further, it is possible to obtain an image with high sharpness in which image quality deterioration (blurring) due to vibration is suppressed.

  The X-ray tube described in Japanese Patent No. 3090910 and the like cited as an example has a concern that an X-ray dose cannot be obtained at the expense of reduction in size and weight. Since the dose of X-rays per one imaging at each moving position is small, it is preferable.

  Since the identifier indicating the imaging position is attached to the image data, the imaging is not performed in the order of the imaging positions, such as imaging by moving the X-ray source in a certain direction such as the left end to the right end of the horizontal bar 23. However, the shooting position can be determined from the identifier.

  Since the X-ray shielding sheet 55 covers the region to be imaged of the subject P and the X-ray image capturing system 2, there is a risk that the exposed X-rays leak into the external space and the surrounding human being unrelated to the imaging is exposed. Can be reduced. Further, by exposing the head, legs, etc. other than the region to be imaged to the outside of the space covered with the X-ray shielding sheet 55, the risk of exposure of the subject P to other than the region to be imaged can be reduced. . Imaging can be performed without hesitation even in places where there are many people other than the subject.

  Since the X-ray shielding sheet 55 has flexibility, it can be folded or rolled up when not in use. For example, it is possible to store the X-ray shielding sheet 55 in the horizontal bar 23 with the horizontal bar 23 being hollow.

  Since the middle of the cable 17 is fixed by the cable fixing tool 56 and the tip thereof is bent and accommodated in the X-ray shielding sheet 55, the cable 17 can be compactly assembled. It is possible to prevent accidents such as the cable 17 being caught by a foot and falling, or the cable 17 being pulled out to interrupt photographing. The cable 19 that connects the cassette 11 and the imaging control device 12 may similarly accommodate a bent portion in the X-ray shielding sheet 55.

  A winding portion 60 shown in FIG. 8 may be provided in the cable 17 in order to achieve accident prevention by the cable and improvement in cable storage and portability. When not in use, the cable 17 is stored in the winding unit 60, and when in use, the cable 17 is pulled out from the winding unit 60 by a required length. As shown in the figure, the winding portion 60 may be attached to the support leg 22. Alternatively, the photographing control device 12 may be provided with a winding unit, and the cable 17 may be wound around and stored in the photographing control device 12. In FIG. 8, the X-ray source 10a and the like are omitted.

[Second Embodiment]
In the first embodiment, an example in which imaging and movement of the X-ray sources 10a and 10b are alternately repeated has been described. In this embodiment, imaging is performed by simultaneously moving and stopping the X-ray sources 10a and 10b.

  In FIG. 9 showing the timing chart of the present embodiment, the X-ray sources 10 a and 10 b are simultaneously moved and stopped under the control of the imaging control device 12. After the stop, imaging is immediately performed with the X-ray source 10a, and then imaging is performed with the X-ray source 10b. While one of the X-ray sources 10a and 10b is imaging, the other is put on standby at the stop position. Since there is a waiting period, the time is slower than in the first embodiment, but the time required for all imaging is shorter than in the case of using one X-ray source.

  In the first embodiment, since one of the X-ray sources 10a and 10b is moved while the other is taking an image, although the vibration is hardly generated, the image is affected to some extent. On the other hand, in the present embodiment, while one is shooting, the other is waiting without moving, so the influence of vibration can be almost completely eliminated. At the same time, if the X-ray sources 10a and 10b are moved at equal distances in the opposite directions, the countermeasures against vibrations are complete.

  The first and second embodiments may be used in combination. In this case, it is preferable that the aspect of each embodiment can be selected by the radiologist. For example, a drive pattern selection switch denoted by reference numeral 65 in FIG. The first embodiment may be selected when it is desired to finish shooting as soon as possible, and the second embodiment may be selected when it is desired to eliminate the influence of vibration as much as possible.

  The number of X-ray sources is not limited to two in each of the above embodiments. The imaging time can be shortened as the number of X-ray sources is increased. However, if the number is the same as the number of imaging, there are difficulties in terms of mobility and cost, so the number of X-ray sources is suitably about 2 to 5. Even in the case of two or more, each X-ray source performs imaging at a timing that does not overlap each other, as in the above embodiments. When the total number of times of imaging is 40, the number of images may be taken 10 times with one X-ray source if there are four, and 8 times if it is five.

  When the X-ray sources 10a and 10b are moved in the opposite directions to cancel the vibration, the number of X-ray sources is preferably an even number in order to maintain symmetry. Further, as in the first embodiment, each X-ray source 10a, 10b may be moved from the end of the horizontal bar 23 toward the center, or conversely, may be moved from the center toward the end.

  The X-ray source 10a is imaged from the position 1 in FIG. 5 and the X-ray source 10b is imaged from the (N / 2) +1 position, the X-ray source 10a is centered from the left end of the horizontal bar 23, and the X-ray source 10b is Shooting may be performed while moving in the same direction from the center toward the right end. The reverse is also possible. In addition, X-ray source 10a is imaged at position 1 in FIG. 5 and X-ray source 10b is imaged at position 3, and with these intervals kept, 2, 4, 5, 7, 6, 8 and so on. -You may move it to the position.

  Several X-ray sources may be assigned to one connector. Since the number of movements is reduced, the photographing time can be further shortened. Further, imaging may be performed while moving the X-ray source without stopping at each position. In this case, the X-ray source is moved at a relatively low speed in order to suppress the influence of vibration as much as possible.

  It should be noted that the X-ray imaging system according to the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

  For example, in each of the above-described embodiments, the mode in which the X-ray detection unit 44 is operated in response to a command from the imaging control device 12 has been described. However, the X-ray detection unit 44 self-detects X-ray irradiation, and the imaging control device 12 is operated. The X-ray detection unit 44 may be operated without receiving a command from.

  In each of the above-described embodiments, a system that performs tomosynthesis imaging has been described as an example. However, a system that selects any two images from a plurality of images obtained by imaging a plurality of times and performs stereoscopic viewing may be used. In this case, after all the captured images are received by the console 13, any two images are selected by the console 13 and displayed on the display 16, and this is read through stereoscopic glasses or the like. In the case of tomosynthesis shooting, there is a problem that it takes time to generate a reconstructed image. However, when two arbitrary images are selected from a plurality of images and viewed stereoscopically, a subject with depth immediately after shooting is taken. The image information of the sample P can be easily confirmed. For this reason, if a stereoscopic view is performed first, and a lesion is found as a result of the stereoscopic view and there seems to be a problem, if a reconstructed image highlighting the desired tomographic plane is obtained, diagnosis can be carried out quickly and without waste. Efficient.

  The X-ray detection unit 44 is not limited to the direct conversion method of the above-described embodiment, and after the incident X-ray is once converted into visible light by a scintillator, the visible light is used using a solid detection element such as amorphous silicon (a-Si). Alternatively, an indirect conversion method of converting into an electrical signal may be used.

  Although the cassette 11 and the imaging control device 12 are connected by wire with a cable 19, they may be connected wirelessly. In the case of wireless connection, a battery for power supply is mounted on the cassette 11.

  The functions of the control units 42, 46 a, 46 b and the drivers 43, 47 a, 47 b may be provided in the cassette 11 and the moving mechanisms 28 a, 28 b instead of the imaging control device 12. It is also possible to provide the drivers 41a and 41b, which are high voltage generators, separately from the imaging control device 12. Further, instead of the console 13, an identifier may be attached or a reconstructed image may be generated by the imaging control device 12.

  The support legs 22 and the horizontal bar 23 may be configured to be extendable so that the width between the support legs 22 and the distance (SID; Source Image Distance) between the X-ray source 10 and the image receiving surface 20 can be adjusted. Further, the support leg 22 and the horizontal bar 23 may be combined into one by using a foldable joint.

  In many cases, the maximum projection angle of the X-ray sources 10a and 10b by the irradiation aperture of the collimator is about 12 °. When it is desired to change the X-ray irradiation field without changing the size of the irradiation opening of the collimator, the SID is adjusted by extending or contracting the support leg 22. The maximum projection angle is an apex angle of an isosceles triangle formed when a straight line connecting the ends of the irradiation aperture with the focal point of the X-ray tubes 18a and 18b as the apex is used as the base.

  The X-ray shielding sheet 55 may not be large enough to cover the entire system of the above embodiment, but may be large enough to accommodate the bent cable 17.

  The present invention can be applied not only to X-rays but also to imaging systems that use other radiation such as gamma rays.

2 X-ray imaging system 10a, 10b X-ray source 11 Cassette 12 Imaging control device 13 Console 14 Holder 17 Cable 18a, 18b X-ray tube 28a, 28b Moving mechanism 30a, 30b Cold cathode electron source 32a, 32b Target 40a, 40b X-ray source control unit 41a, 41b Driver 42 Cassette control unit 44 X-ray detection unit 46a, 46b Movement mechanism control unit 48a, 48b Drive source 55 X-ray shielding sheet 56 Cable fixture 60 Winding unit 65 Drive pattern selection switch

Claims (15)

N radiation sources for irradiating the subject with radiation;
A radiation image detector for detecting an image by receiving radiation transmitted through the subject;
A holder for movably supporting the n radiation sources with respect to the radiation image detector;
To move the n radiation sources to N positions (N >> n) on the holder so that radiation can be emitted from the n radiation sources at different angles with respect to the radiation image detector. A portable radiographic imaging system, comprising:   The portable radiation according to claim 1, further comprising an image generation device that generates a tomographic image in which a region of interest of a subject is emphasized based on N pieces of image data output from the radiation image detector. Image shooting system. Each of the n radiation sources is moved to approximately N / n positions that do not overlap each other by the moving mechanism,
The portable radiation image capturing system according to claim 1, wherein the radiation is irradiated at a timing that does not overlap each other.   4. The portable radiation source according to claim 1, wherein each of the n radiation sources is responsible for irradiation of radiation in a range obtained by dividing the entire moving range by the moving mechanism into n equal parts. 5. Radiation imaging system.   5. The moving mechanism according to claim 1, wherein the moving mechanism moves another radiation source to the next position when one of the n radiation sources emits radiation. 6. The portable radiographic imaging system according to one item.   6. The portable radiographic imaging system according to claim 1, wherein the moving mechanism simultaneously moves and stops the n radiation sources to a next position. 7.   When one of the n radiation sources is radiating radiation, the moving mechanism moves another radiation source to the next position, or simultaneously moves the n radiation sources to the next position. The portable radiographic imaging system according to claim 1, further comprising operation input means for selecting whether to move or stop.   8. The portable radiographic imaging system according to claim 1, wherein the moving mechanism moves the n radiation sources in a direction in which mutual vibrations accompanying the movement cancel each other. .   The portable radiographic imaging system according to any one of claims 1 to 8, wherein the image generation apparatus stores an identifier representing a position of the radiation source and image data in association with each other.   The portable radiographic imaging system according to any one of claims 1 to 9, wherein the holder has a curved trajectory such that the radiation source faces the radiological image detector at each position. .   The portable radiographic imaging system according to claim 1, wherein n is 2. 11.   The portable radiation image capturing system according to claim 1, wherein the radiation source includes a fixed anode radiation tube.   The portable radiographic imaging system according to any one of claims 1 to 12, wherein the radiation source includes a radiation tube using a cold cathode electron source. A radiation image detector for detecting an image by receiving radiation transmitted through the subject;
A holder that supports n radiation sources for irradiating the subject with radiation so as to be movable with respect to the radiation image detector;
To move the n radiation sources to N positions (N >> n) on the holder so that radiation can be emitted from the n radiation sources at different angles with respect to the radiation image detector. A portable radiographic imaging set, comprising: A support for supporting n radiation sources for irradiating the subject with radiation,
In order to move the support to N positions (N >> n) so that radiation can be emitted from a radiation source at different angles with respect to a radiation image detector that receives an image transmitted through a subject and detects an image. A holder for use in a portable radiographic imaging system.

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