WO2019202695A1 - Système d'imagerie par rayons x - Google Patents

Système d'imagerie par rayons x Download PDF

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Publication number
WO2019202695A1
WO2019202695A1 PCT/JP2018/016092 JP2018016092W WO2019202695A1 WO 2019202695 A1 WO2019202695 A1 WO 2019202695A1 JP 2018016092 W JP2018016092 W JP 2018016092W WO 2019202695 A1 WO2019202695 A1 WO 2019202695A1
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Prior art keywords
ray
grid
irradiation
value
subject
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PCT/JP2018/016092
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English (en)
Japanese (ja)
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十磨 平井
宮田　博
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株式会社島津製作所
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Priority to PCT/JP2018/016092 priority Critical patent/WO2019202695A1/fr
Publication of WO2019202695A1 publication Critical patent/WO2019202695A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/06—Diaphragms

Definitions

  • the present disclosure relates to an X-ray imaging system, and in particular, includes an X-ray irradiation unit that emits X-rays toward a subject, and an X-ray detection unit that detects X-rays emitted from the X-ray irradiation unit and transmitted through the subject.
  • the present invention relates to an X-ray imaging system provided.
  • the X-ray imaging system further includes an X-ray dose sensor that detects an X-ray dose incident on the X-ray detection unit,
  • X-ray dose sensor that detects an X-ray dose incident on the X-ray detection unit
  • Patent Document 1 discloses that X-ray irradiation from an X-ray irradiation unit is stopped when an integrated value of X-ray dose detected by an X-ray dose sensor reaches a predetermined value.
  • the predetermined value is set to an appropriate value so that a captured image with good image quality can be obtained while suppressing the exposure amount of the subject.
  • Such a function is also called a “photo timer”. With this phototimer, the X-ray dose incident on the X-ray detection unit can be made constant regardless of the body thickness of the subject, and stable X-ray imaging independent of the subject becomes possible.
  • JP 2016-135176 A Japanese Patent No. 6006193
  • a scattered radiation removing member called a “grid” may be installed between the subject and the X-ray detection unit in order to prevent the scattered radiation from entering the X-ray detection unit.
  • the grid By using the grid, it is possible to remove the scattered radiation incident on the X-ray detection unit and improve the contrast of the captured image. On the other hand, since several tens of X-rays irradiated from the X-ray irradiation unit are generally absorbed by the grid, the irradiation time becomes longer when the grid is used than when the grid is not used. Therefore, for example, a method of removing the influence of scattered rays from a captured image by image processing by estimating the scattered dose by not using a grid for a thin subject such as a child (see, for example, Patent Document 2) In some cases, the grid is not used.
  • the present disclosure has been made to solve such a problem, and an object of the present disclosure is to provide an X-ray imaging system capable of appropriately adjusting an irradiation time by a phototimer according to nonuse of a grid. .
  • the X-ray imaging system of the present disclosure includes an X-ray irradiation unit, an X-ray detection unit, a support unit, an X-ray dose sensor, and a control unit.
  • the X-ray irradiation unit irradiates the subject with X-rays.
  • the X-ray detection unit detects X-rays emitted from the X-ray irradiation unit and transmitted through the subject.
  • the support unit supports a grid that suppresses incidence of scattered rays generated when the X-rays irradiated from the X-ray irradiation unit pass through the subject to the X-ray detection unit.
  • the X-ray dose sensor detects an X-ray dose incident on the X-ray detection unit.
  • the control unit adjusts the irradiation time of the X-rays irradiated to the subject based on the integrated value ( ⁇ R) of the X-ray dose detected by the X-ray dose sensor (photo timer function).
  • the control unit determines that the integrated value reaches the first value (L1). Irradiation from the line irradiation unit is stopped.
  • the control unit is a second value in which the integrated value is larger than the first value.
  • (L2) is reached, the irradiation from the X-ray irradiation unit is stopped.
  • a photo timer for adjusting the X-ray irradiation time based on the integrated value ( ⁇ R) of the X-ray dose incident on the X-ray detection unit is provided on the grid. If the same setting as in use is used, irradiation is stopped by the phototimer before sufficient primary X-rays (X-rays necessary for interpretation) enter the X-ray detector. Therefore, in the X-ray imaging system of the present disclosure, when X-ray imaging is performed in the first state in which the grid is used, irradiation is stopped when the integrated value reaches the first value (L1).
  • the second value is detected when the integrated value reaches the first value when X-ray imaging is performed in a second state in which no grid is used. It is determined based on the shortage of the primary dose reaching the part. The shortage of the primary dose is calculated from the first value and the scattered dose absorbed by the grid when X-ray imaging is performed in the first state where the grid is used.
  • the second value can be determined from the first value and the scattered dose absorbed by the grid without depending on trial and error.
  • the second value is an irradiation time when the X-ray imaging of the subject is performed in the second state, and the X-ray imaging of the subject is performed in the first state. It is set to be shorter than the irradiation time.
  • the irradiation time can be shortened by not using the grid.
  • the X-ray imaging system further includes an input unit for the user to select whether to perform X-ray imaging of the subject in the first state or the second state. Then, when the first state is selected in the input unit, the control unit stops irradiation from the X-ray irradiation unit when the integrated value reaches the first value. On the other hand, when the second state is selected in the input unit, the control unit stops the irradiation from the X-ray irradiation unit when the integrated value reaches the second value.
  • the user can finally determine whether to use or not use the grid after confirming the necessity of the grid and whether or not the grid is mounted.
  • the X-ray imaging system further includes a detection unit that detects whether or not a grid is attached to the support unit. Then, when the mounting of the grid is detected by the detection unit (use of grid), the control unit stops the irradiation from the X-ray irradiation unit when the integrated value reaches the first value. On the other hand, when the mounting of the grid is not detected by the detection unit (grid not used), the control unit stops the irradiation from the X-ray irradiation unit when the integrated value reaches the second value.
  • control unit preferably performs imaging by estimating the scattered dose incident on the X-ray detection unit when X-ray imaging of the subject is performed in the second state (not using the grid).
  • the scattered radiation removing process for removing the scattered radiation from the image is configured to be executable.
  • the second value when the scattered radiation removal process is executed is larger than the second value when the scattered radiation removal process is not executed.
  • the X-ray imaging system further includes an input unit for the user to select whether or not to execute the scattered radiation removal process. Then, when the non-execution of the scattered radiation removal process is selected in the input unit, the control unit starts from the X-ray irradiation unit when the integrated value reaches a third value (L2A) larger than the first value. Stop irradiation. On the other hand, when execution of scattered radiation removal processing is selected in the input unit, the control unit, when the integrated value reaches the fourth value (L2B) larger than the third value, Stop irradiation.
  • L2A third value
  • Stop irradiation On the other hand, when execution of scattered radiation removal processing is selected in the input unit, the control unit, when the integrated value reaches the fourth value (L2B) larger than the third value, Stop irradiation.
  • the user can determine, for example, whether or not to execute the scattered radiation removal process after confirming the subject.
  • the X-ray imaging system of the present disclosure it is possible to appropriately adjust the irradiation time by the phototimer according to whether the grid is used or not.
  • FIG. 1 is an overall configuration diagram of an X-ray imaging system according to a first embodiment of the present disclosure. It is a block diagram which shows the control system of the X-ray imaging system shown in FIG. It is a schematic diagram explaining the function of a grid. It is the figure which showed the example of a display of the operation panel of a high voltage apparatus. It is a figure explaining a phototimer function. It is a figure explaining the phototimer when not using a grid with the case where a grid is used with respect to the same subject. It is a figure explaining the phototimer in the X-ray imaging system according to Embodiment 1.
  • FIG. 6 is a flowchart illustrating phototimer processing executed in the X-ray imaging system according to the first embodiment.
  • FIG. 6 is a diagram for explaining a phototimer in the X-ray imaging system according to the second embodiment.
  • FIG. 6 is a flowchart illustrating phototimer processing executed in the X-ray imaging system according to the second embodiment.
  • FIG. 10 is a diagram showing a display example of an operation panel in the second embodiment. It is a flowchart for demonstrating a scattered-radiation removal process.
  • FIG. 1 is an overall configuration diagram of an X-ray imaging system according to the first embodiment of the present disclosure.
  • FIG. 2 is a block diagram showing a control system of the X-ray imaging system shown in FIG.
  • the case where X-ray imaging is performed on a subject placed in a prone position on the imaging table 20 will be described as a representative example.
  • the present invention can also be applied to a case where X-ray imaging is performed on a subject placed in a standing position in front of a partition that determines a standing position.
  • the X-ray imaging system 100 includes an irradiation unit 10, an imaging table 20, a console unit 40, and a high voltage device 50.
  • the irradiation unit 10 and the imaging table 20 are provided in the imaging room 101, and the console unit 40 and the high voltage device 50 are provided in the operation room 102 that is separated from the imaging room 101 by the partition wall 103.
  • the irradiation unit 10, the imaging table 20, the console unit 40, and the high voltage device 50 are configured to be able to communicate with each other by wire or wireless.
  • the irradiation unit 10 includes an X-ray tube 11, a collimator 12, a base 13, and a moving unit 14.
  • the X-ray tube 11 generates X-rays according to imaging conditions such as tube voltage, tube current, and irradiation time set by the high-voltage device 50, and irradiates the subject 30 with X-rays.
  • the X-ray tube 11 is attached to the moving unit 14, and can be moved in the vertical direction and the horizontal direction with respect to the base 13 by the moving unit 14.
  • the collimator 12 is attached to the X-ray tube 11 and adjusts the X-ray irradiation field irradiated from the X-ray tube 11.
  • the imaging table 20 includes a top plate 21 on which the subject 30 is placed, a grid 22 and a support unit 23, a detection unit 24, an X-ray dose sensor 25, and a flat panel detector (hereinafter referred to as “FPD (Flat Panel Detector)”. 26).
  • FPD Full Panel Detector
  • the grid 22 is a member for suppressing the incident of the scattered rays generated when the X-rays irradiated from the X-ray tube 11 through the collimator 12 pass through the subject 30 to the FPD 26.
  • the grid 22 is an intermediate material such as aluminum in which metal foils composed of lead or the like having a high X-ray absorption rate are arranged in a strip shape or a lattice shape, and the X-ray absorption rate is low (high transmittance). It is a plate-like member that fills the gap, and is disposed between the top plate 21 and the FPD 26 (actually, the X-ray dose sensor 25 is disposed between the grid 22 and the FPD 26).
  • FIG. 3 is a schematic diagram for explaining the function of the grid 22.
  • X-rays irradiated from an X-ray tube 11 travel straight through the subject 30 and reach the FPD 26 (primary X-rays) when passing through the subject 30.
  • 60 and scattered rays (secondary X-rays) 61 that travel in the subject 30 while changing directions.
  • the direct line (primary X-ray) 60 passes through the grid 22, and the scattered radiation 61 whose direction has changed in the subject 30 is the grid. 22 is absorbed.
  • the grid 22 can suppress the scattered radiation 61 from entering the FPD 26.
  • most of the X-rays incident on the FPD 26 become direct rays (primary X-rays) 60, so that the contrast of the captured image is improved.
  • the grid 22 When the grid 22 is used, several tens of% of the irradiated X-rays are absorbed by the grid 22 as scattered rays, so that the X-ray dose incident on the FPD 26 is smaller than when the grid 22 is not used. Therefore, when the grid 22 is used, the contrast of the captured image is improved as compared with when the grid 22 is not used, but the imaging time becomes longer.
  • the support portion 23 supports the grid 22 in a detachable manner. That is, in the first embodiment, the grid 22 can be removed from the support portion 23, and X-ray imaging can be performed without using the grid 22 depending on the case where the subject is a child or the imaging region. When performing X-ray imaging using the grid 22, the grid 22 is attached to the support portion 23.
  • the detection unit 24 (FIG. 2) detects whether or not the grid 22 is attached to the support unit 23, and outputs a signal corresponding to the detection result to the console unit 40.
  • the detection unit 24 is configured by, for example, a limit switch that outputs an ON signal when the grid 22 is attached to the support unit 23.
  • the X-ray dose sensor 25 is disposed between the support portion 23 and the FPD 26 and detects the X-ray dose incident on the FPD 26.
  • the X-ray dose detected by the X-ray dose sensor 25 is output to the high voltage device 50.
  • the X-ray dose sensor 25 is used as a phototimer, and is controlled so that the X-ray irradiation from the irradiation unit 10 stops when the integrated value of the X-ray dose detected by the X-ray dose sensor 25 reaches a predetermined value. .
  • Various known X-ray dose sensors can be adopted as the X-ray dose sensor 25.
  • the FPD 26 detects X-rays irradiated from the X-ray tube 11 and transmitted through the subject 30.
  • the FPD 26 may be a so-called indirect FPD in which incident X-rays are converted into fluorescence by a phosphor and then converted into an electrical signal, or incident X-rays are converted by an X-ray conversion film such as amorphous selenium (a-Se). It may be a so-called direct FPD that directly converts a line into an electric signal.
  • various known FPDs can be adopted.
  • the console unit 40 of the operation room 102 includes a display unit 41 and an operation unit 42.
  • the display unit 41 displays various information related to X-ray imaging.
  • the display unit 41 displays information on the subject 30 (age, gender, physique, imaging region, etc.) and imaging conditions (tube voltage, tube current, imaging region, imaging distance, etc.), and after imaging, The X-ray image thus displayed is displayed.
  • information on the subject 30 is input through the operation unit 42, and shooting conditions are set in the high voltage device 50 (described later).
  • the operation unit 42 is an input means for an operator to input various settings of the X-ray imaging system 100, operations of various devices, and the like.
  • the operator can input information about the subject 30 from the operation unit 42, operate the moving unit 14 of the irradiation unit 10 according to the imaging region, and operate the display state of the display unit 41.
  • Information about the subject 30 may be read from an external system (not shown) that manages patient information.
  • X-ray imaging is performed in a state where the grid 22 is mounted on the support portion 23 (using the grid) and a state where the grid 22 is detached from the support portion 23 (not using the grid). Can be performed. Then, the display unit 41 further displays whether or not the grid 22 is attached to the support unit 23 in accordance with a signal from the detection unit 24 of the imaging table 20.
  • the operator finally determines whether the grid 22 is used or not after confirming whether or not the grid 22 is mounted on the display unit 41.
  • the voltage device 50 is set.
  • the setting of use / non-use of the grid 22 is further displayed on the display unit 41 as one item of shooting conditions.
  • the high voltage device 50 includes a switch 51, an operation panel 52, and a control unit 53.
  • the switch 51 is an input means for an operator to instruct the start of X-ray imaging. When the switch 51 is operated by the operator, X-ray imaging is started.
  • the operation panel 52 is an operation device for an operator to set shooting conditions and display the setting state.
  • the operator can set imaging conditions such as tube voltage, tube current, and imaging region from the operation panel 52. As shown in FIG. 4, the operator can further set use / non-use of the grid 22 as an imaging condition from the operation panel 52.
  • the set shooting conditions are displayed on the operation panel 52 and also transmitted to the console unit 40.
  • the operation panel 52 is configured by, for example, a touch panel display that can be input on the display screen.
  • the control unit 53 includes an arithmetic device, a memory, an input / output buffer, and the like (all not shown).
  • the controller 53 controls the tube voltage and tube current during X-ray imaging to set values for imaging conditions. Further, the control unit 53 adjusts the irradiation time of the X-rays irradiated to the subject 30. Specifically, the control unit 53 receives the detection value of the X-ray dose sensor 25 during X-ray imaging, and the X-ray dose detected by the X-ray dose sensor 25 after the X-ray irradiation from the X-ray tube 11 is started. And the X-ray irradiation time is adjusted based on the integrated value (photo timer function).
  • FIG. 5 is a diagram for explaining the phototimer function.
  • the horizontal axis represents time
  • the vertical axis represents the integrated value ⁇ R of the X-ray dose R detected by the X-ray dose sensor 25.
  • FIG. 5 shows an example in which X-ray imaging is performed with the grid 22 mounted on the support portion 23.
  • irradiation from the X-ray tube 11 is started at time t0.
  • the integrated value ⁇ R of the X-ray dose R detected by the X-ray dose sensor 25 reaches the set value L1
  • the irradiation from the X-ray tube 11 is stopped.
  • irradiation of the subject 1 is stopped when the integrated value ⁇ R reaches the set value L1 at time t1.
  • Irradiation of the subject 2 is stopped when the integrated value ⁇ R reaches the set value L1 at time t2.
  • the set value L1 is set in advance according to the imaging conditions (imaging site, tube current, tube voltage, etc.), and is stored in the memory of the control unit 53.
  • the amount of scattered radiation generated when X-rays pass through the subject depends on the body thickness of the subject, and the subject thickness is large. The more the scattered radiation is generated. Therefore, the thicker the subject, the smaller the amount of direct lines reaching the FPD 26 (when using the grid).
  • the irradiation time for the subject 2 is longer than the irradiation time for the subject 1, it is understood that the body thickness of the subject 2 is thicker than the body thickness of the subject 1.
  • X-rays are scattered in the subject 30 when the X-rays pass through the subject 30 as described above. Scattered rays that travel while changing the direction in the subject 30 are generated. When scattered rays are incident on the FPD 26, the contrast of the captured image decreases. Therefore, in order to prevent the scattered radiation from entering the FPD 26, the X-ray imaging system 100 mounts the grid 22 on the support unit 23 and interposes the grid 22 between the subject 30 and the FPD 26 to perform X-ray imaging. Can be performed.
  • the scattered radiation incident on the FPD 26 can be removed and the contrast of the captured image can be improved.
  • the X-ray irradiation time becomes longer when the grid 22 is used than when the grid 22 is not used. .
  • the grid 22 is not used for the thin subject 30 such as a child, or a method of estimating the scattered dose and removing the influence of scattered rays from the captured image by image processing (described later) is used. In some cases, the grid 22 may not be used.
  • the grid 22 can be removed from the support unit 23 so that X-ray imaging can be performed without using the grid 22 so as to cope with such a case.
  • the above-described phototimer that adjusts the X-ray irradiation time based on the integrated value ⁇ R of the X-ray dose R incident on the FPD 26 is used for the grid 22.
  • the X-ray irradiation time by the phototimer becomes extremely short when the grid 22 is not used.
  • the photographed image is of low quality.
  • FIG. 6 is a diagram for explaining the phototimer when the grid is used for the same subject and when the grid is not used.
  • FIG. 6 is shown as a reference example corresponding to the prior art. Referring to FIG. 6, in this example also, it is assumed that X-ray irradiation is started at time t0. When the grid is used, irradiation ends at time t12.
  • the scattered radiation also reaches the FPD. Therefore, the time t11 when the integrated value ⁇ R of the X-ray dose R reaches the set value L1 is much earlier than the arrival time t12 when the grid is used. In addition, since the X-rays that have reached the FPD contain many scattered rays, the obtained captured image also has a low quality.
  • the X-ray imaging system 100 when the X-ray imaging of the subject 30 is performed with the grid 22 attached to the support unit 23 (using the grid 22), the X-ray dose incident on the FPD 26 When the integrated value ⁇ R of R reaches the first set value, irradiation from the X-ray tube 11 is stopped.
  • the second set value in which the integrated value ⁇ R is larger than the first set value. The irradiation from the X-ray tube 11 is stopped.
  • an appropriate irradiation time is secured and a good captured image can be obtained.
  • FIG. 7 is a diagram for explaining a phototimer in X-ray imaging system 100 according to the first embodiment.
  • X-ray irradiation is started at time t0.
  • the grid 22 is used, the irradiation from the X-ray tube 11 is stopped when the integrated value ⁇ R of the X-ray dose R detected by the X-ray dose sensor 25 reaches the set value L1.
  • the irradiation is stopped when the integrated value ⁇ R reaches the set value L1 at time t23.
  • the grid 22 when the grid 22 is not used, irradiation from the X-ray tube 11 is stopped when the integrated value ⁇ R of the X-ray dose R reaches a set value L2 larger than the set value L1.
  • the irradiation time is extended by increasing the set value of the phototimer (the threshold value of the integrated value ⁇ R of the X-ray dose R), and the irradiation time can be secured.
  • the set value L2 is also set in advance according to the imaging conditions (imaging site, tube current, tube voltage, etc.), and is stored in the memory of the control unit 53.
  • the set value L2 may be determined from the set value L1 as follows. As described above, when a grid is used, it is known that the scattered dose absorbed by the grid is several tens of percent of the dose reaching the grid. Therefore, when the dose (integrated value) reaching the grid 22 is A and the scattered dose absorbed by the grid 22 is B% of the dose A, the set value L1 is A ⁇ (100 ⁇ B) / 100.
  • the primary dose threshold (integrated value) of the phototimer is set to the set value L1 when the grid 22 is not used
  • the primary dose is (100-B)% and the scattered dose is B in the dose L1 reaching the FPD 26. % Will be included.
  • the primary dose needs to reach the FPD 26 by L1. Therefore, when the threshold value of the phototimer is set to the set value L1 when the grid 22 is not used, the FPD 26 The primary dose to reach will be insufficient by L1 ⁇ B / 100.
  • the primary dose required to obtain a captured image with good visibility can be obtained by setting the dose threshold value (integrated value) of the phototimer to the set value L2 represented by the following equation. Can be secured.
  • L2 L1 + (L1 ⁇ B / 100) + [(L1 ⁇ B / 100) ⁇ B / (100 ⁇ B)]
  • the set value L2 is the irradiation time when the grid 22 is not used (t0 to t22). It is set to be shorter than the irradiation time (t0 to t23) when the grid 22 is used.
  • the irradiation time from when the grid 22 is used until the integrated value ⁇ R reaches the set value L1 when the grid 22 is not used. (T0 to t21) can be estimated.
  • the set value L2 can be easily determined such that the irradiation end time does not exceed t23.
  • FIG. 8 is a flowchart illustrating phototimer processing executed in X-ray imaging system 100 according to the first embodiment. A series of processing shown in this flowchart is started when the photographing condition is set from the operation panel 52 in the high voltage apparatus 50 and the switch 51 is turned on by the operator.
  • the control unit 53 of the high voltage device 50 sets the imaging conditions (tube voltage, tube current, imaging region, grid use / non-use, etc.) set on the operation panel 52 to the operation panel 52 or the imaging conditions. Is read from the temporarily stored memory (step S10).
  • control unit 53 determines whether or not to perform X-ray imaging using the grid 22 based on the read imaging conditions, that is, with the grid 22 mounted on the support unit 23 (step S20). ). If it is determined in step S20 that grid 22 is used (YES in step S20), control unit 53 sets photo timer set value L to set value L1 (step S30). On the other hand, when it is determined in step S20 that the grid 22 is not used (NO in step S20), the control unit 53 sets the set value L of the phototimer to a set value L2 (FIG. 7) larger than the set value L1 (FIG. 7). Step S40).
  • the control unit 53 starts X-ray irradiation from the X-ray tube 11 and starts X-ray imaging (step S50).
  • the control unit 53 acquires the detected value of the X-ray dose R detected by the X-ray dose sensor 25 from the X-ray dose sensor 25 (step S60). Further, the control unit 53 integrates the acquired X-ray dose R to calculate an integrated value ⁇ R of the X-ray dose R from the start of X-ray irradiation (step S70).
  • control unit 53 determines whether or not the calculated integrated value ⁇ R is greater than or equal to the set value L set in step S30 or S40 (step S80). If integrated value ⁇ R of X-ray dose R is smaller than set value L (NO in step S80), the process returns to step S60.
  • step S80 If it is determined in step S80 that the integrated value ⁇ R of the X-ray dose R is greater than or equal to the set value L (YES in step S80), the control unit 53 stops X-ray irradiation from the X-ray tube 11 and X-rays.
  • the shooting is finished (step S90). That is, when imaging is performed using the grid 22, the imaging ends when the integrated value ⁇ R of the X-ray dose R reaches the set value L1, and when imaging is performed without using the grid 22, X When the integrated value ⁇ R of the dose R reaches the set value L2 (FIG. 7), the imaging is finished.
  • the integrated value ⁇ R of the X-ray dose R detected by the X-ray dose sensor 25 is the grid value.
  • the set value L2 larger than the set value L1 at the time of use is reached, irradiation from the X-ray tube 11 is stopped. Thereby, when X-ray imaging is performed without using the grid 22, an appropriate irradiation time is ensured, and a good captured image can be obtained.
  • the setting value L2 when the grid 22 is not used is set so that the irradiation time when the grid 22 is not used is shorter than the irradiation time when the grid 22 is used (FIG. 7). Thereby, irradiation time can be shortened by making the grid 22 non-use.
  • the scattered dose generated when X-rays pass through the subject 30 is estimated, and the influence of the scattered radiation from the captured image by image processing is estimated. It is possible to execute a scattered radiation removal process for removing the. By executing the scattered radiation removal process, the contrast of the captured image can be improved without using the grid 22, so that it is possible to shorten the irradiation time by not using the grid 22. Become.
  • the phototimer is set at the same setting as when the grid 22 is used, the X-ray irradiation time by the phototimer becomes extremely short as described above. Furthermore, since the amount of direct rays occupying the X-rays incident on the FPD 26 within the irradiation time is small (since many scattered rays are included), a good image cannot be obtained even if the scattered rays are removed.
  • the set value L2 of the phototimer when X-ray imaging is performed without using the grid 22 is further divided depending on whether or not the scattered radiation removal process is executed. Specifically, in the case where X-ray imaging is performed without using the grid 22, when the scattered radiation removal process is performed, the photo is taken so that the irradiation time is longer than when the scattered radiation removal process is not performed. A timer is set.
  • FIG. 9 is a diagram for explaining a phototimer in X-ray imaging system 100 according to the second embodiment.
  • X-ray irradiation is started at time t0.
  • the grid 22 is used, the irradiation from the X-ray tube 11 is stopped when the integrated value ⁇ R of the X-ray dose R detected by the X-ray dose sensor 25 reaches the set value L1.
  • irradiation is stopped when the integrated value ⁇ R reaches the set value L1 at time t34.
  • the irradiation time can be set more appropriately by dividing the set value L2 of the phototimer depending on whether or not the scattered radiation removal process is executed.
  • the set values L2A and L2B are also set in advance according to the imaging conditions (imaging site, tube current, tube voltage, etc.) and stored in the memory of the control unit 53, similarly to the set value L1.
  • the set value L2B is equal to the irradiation time (t0 to t33) when the scattered radiation removal process is performed, as described for the set value L2 in the first embodiment, from the irradiation time (t0 to t34) when the grid 22 is used. Is set to be shorter.
  • FIG. 10 is a flowchart illustrating phototimer processing executed in X-ray imaging system 100 according to the second embodiment. This flowchart corresponds to the flowchart in the first embodiment shown in FIG. 8, and in the series of processing shown in this flowchart, the shooting conditions are set from the operation panel 52 in the high voltage device 50. It is started when the switch 51 is turned on by the operator.
  • step S210 and S220 are the same as the processes in steps S10 and S20 shown in FIG. If it is determined in step S220 that the grid 22 is used (YES in step S220), the control unit 53 sets the set value L of the phototimer to the set value L1 (step S230).
  • step S220 determines whether or not to perform scattered radiation removal processing on the captured image (step S240).
  • whether or not to perform the scattered radiation removal process is set by the operator on the operation panel 52 of the high voltage device 50 as shown in FIG.
  • step S240 If it is determined in step S240 that the scattered radiation removal process is not performed (NO in step S240), the control unit 53 sets the set value L of the phototimer to the set value L2A (L2A> L1) (step S242). On the other hand, when it is determined in step S240 that the scattered radiation removal process is to be performed (YES in step S240), control unit 53 sets set value L of the phototimer to set value L2B that is larger than set value L2A (FIG. 9). (Step S244).
  • step S250 When the set value L of the phototimer is set in step S230, S242 or S244, the control unit 53 starts X-ray irradiation from the X-ray tube 11 and starts X-ray imaging (step S250). .
  • the processing in steps S250 to S290 is the same as the processing in steps S50 to S90 shown in FIG. 8, and therefore, description thereof will not be repeated.
  • FIG. 12 is a flowchart for explaining the scattered radiation removal process. A series of processes shown in this flowchart is performed after X-ray imaging is performed in a state where the grid 22 is not used and the operation panel 52 of the high voltage apparatus 50 is selected to perform the scattered radiation removal process. This is executed in an image processing unit (not shown) of the console unit 40.
  • the image processing unit acquires a photographed X-ray image (step S310).
  • the image processing unit estimates the body thickness of the subject 30 in the captured image (step S320).
  • the amount of scattered radiation generated is estimated in step S330, which will be described later, and it is known that the amount of scattered radiation generated depends on the body thickness of the subject.
  • the thickness is estimated.
  • the body thickness of the subject 30 can be estimated from the photographing distance at the time of photographing, the irradiation condition (tube voltage and tube current), and the detected value of the X-ray dose R by the X-ray dose sensor 25.
  • the X-ray detection amount is estimated based on the photographing distance and the irradiation condition at the time of photographing, and is absorbed by the subject 30 based on the difference from the detected value of the X-ray dose R at the time of photographing.
  • the dose can be calculated, and the body thickness of the subject 30 can be estimated based on the absorbed dose.
  • the image processing unit estimates the amount of scattered radiation generated at the time of photographing from the body thickness of the subject 30 estimated in step S320 (step S330). It is known that the amount of scattered radiation varies depending on the energy of irradiated X-rays and the body thickness of the subject, and the relationship between the energy of irradiated X-rays, the body thickness of the subject and the amount of scattered radiation generated. Is prepared in advance with a map or the like, the amount of scattered radiation generated can be estimated from the energy of the irradiated X-rays at the time of imaging and the body thickness estimated in step S320.
  • the image processing unit subtracts the scattered radiation estimated in step S330 from the captured image acquired in step S310 (step S340). Thereby, the influence of scattered radiation is removed from the captured image. Further, the image processing unit executes noise reduction processing (step S350). As an example, the image processing unit removes a high-frequency noise component from the captured image data by applying a filter that removes the high-frequency component to the captured image data from which the scattered line segment has been removed in step S340. As described above, the influence of the scattered radiation can be removed from the captured image captured without using the grid 22.
  • the scattered radiation removal process when the X-ray imaging is performed without using the grid 22, when the scattered radiation removal process is performed, the scattered radiation removal process is not performed.
  • the photo timer is set so that the irradiation time becomes longer.
  • the use / non-use of the grid 22 is set by the operator from the operation panel 52 of the high voltage device 50. However, whether or not the grid 22 is attached to the support portion 23 is determined.
  • the use / non-use of the grid 22 may be automatically set based on the detection result of the detection unit 24 that detects whether or not the grid 22 is used.
  • the X-ray tube 11 and the collimator 12 correspond to an example of the “X-ray irradiation unit” in the present disclosure
  • the FPD 26 corresponds to an example of the “X-ray detection unit” in the present disclosure
  • the operation panel 52 corresponds to an example of the “input unit” in the present disclosure.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Medical Informatics (AREA)
  • Engineering & Computer Science (AREA)
  • Radiology & Medical Imaging (AREA)
  • Biomedical Technology (AREA)
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  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
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Abstract

Un FPD (26) détecte les rayons X émis par une unité d'irradiation (10) et transmis à travers un sujet. Un capteur de quantité de rayons X (25) détecte la quantité de rayons X incidents sur le FPD (26). Sur la base d'une valeur intégrée de la quantité de rayons X détectée par le capteur de quantité de rayons X (25), une unité de commande (53) règle le temps d'irradiation des rayons X avec lesquels le sujet est irradié. Dans le cas où un cliché radiographique du sujet est capturé à l'aide d'une grille, l'unité de commande (53) arrête le rayonnement provenant de l'unité d'irradiation (10) lorsque ladite valeur intégrée atteint une première valeur. En revanche, dans le cas où un cliché radiographique du sujet est capturé sans utiliser de grille, l'unité de commande (53) arrête le rayonnement provenant de l'unité d'irradiation (10) lorsque ladite valeur intégrée atteint une seconde valeur supérieure à la première valeur.
PCT/JP2018/016092 2018-04-19 2018-04-19 Système d'imagerie par rayons x WO2019202695A1 (fr)

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CN108937984A (zh) * 2017-05-19 2018-12-07 佳能株式会社 放射线摄像装置、放射线摄像系统和剂量指标管理方法
US11426138B2 (en) 2017-05-19 2022-08-30 Canon Kabushiki Kaisha Radiographing apparatus, radiographing system, and dose index management method

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