Radiation imaging device, radiation imaging system, and method for controlling radiation imaging device

Abstract

To correct an output value including an error of an acceleration sensor or gyro sensor that is used as a posture measurement unit for a radiographic apparatus to improve accuracy for positioning a radiation generator and the radiographic apparatus.SOLUTION: A radiographic apparatus includes: a posture measurement unit for measuring information relating to a posture of the radiographic apparatus. The posture measurement unit corrects an output value of the posture measurement unit according to operation of radiographic imaging.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus, a radiation detector, and a method for controlling a radiation imaging apparatus. [Background technology]

[0002] Currently, flat panel detectors (FPDs) made of semiconductor materials are widely used as radiation detectors for medical imaging diagnosis and non-destructive testing using radiation such as X-rays. Radiography devices that combine such radiation detectors with radiation generators that generate radiation are in use.

[0003] As a function of such a radiation imaging device, a function has been put into practical use that supports alignment of the irradiation field surface of the radiation irradiated from the radiation generating device and the incident surface of the radiation detector by calculating and displaying the posture of the radiation generating device and the radiation detector.

[0004] A method for calculating the attitude of the radiation generating device and the radiation detector is to provide an acceleration sensor or a gyro sensor in each and calculate the attitude from the acceleration output value of the acceleration sensor or the angular velocity output value of the gyro sensor.

[0005] For example, Patent Document 1 discloses a radiography system that includes a support control unit that provides a tilt angle detection unit using an acceleration sensor or a gyro sensor in a radiography device and a radiation generation device, and that performs radiography support processing based on the value from the tilt angle detection unit. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-007923 Summary of the Invention [Problem to be solved by the invention]

[0007] The acceleration sensor and the gyro sensor contain errors in their output values, and therefore, when an attempt is made to determine the attitude of the radiographic apparatus using the output values ​​of these sensors, the calculation may not be accurate.

[0008] An object of the present invention is to correct an output value containing an error of an acceleration sensor or gyro sensor used as an attitude measurement unit of a radiation imaging apparatus, and to improve the accuracy of alignment between a radiation generating apparatus and a radiation imaging apparatus. [Means for solving the problem]

[0009] The object of the present invention is to A radiographic imaging device for acquiring a radiographic image based on radiation, The radiation imaging apparatus includes an orientation measurement unit that measures the orientation of the radiation imaging apparatus, and the orientation measurement unit confirming an output value of the posture measurement unit based on the input of the imaging protocol settings; The radiographic imaging device is in a stationary state. to handle The output value was confirmed. Based on the output value of the posture measurement unit offset Making corrections The above-mentioned problems are solved by a radiographic apparatus characterized in that: [Effects of the Invention]

[0010] According to the present invention, it is possible to correct the output value including an error of the acceleration sensor or gyro sensor used as the attitude measurement unit of the radiation imaging apparatus, and improve the accuracy of alignment between the radiation generating apparatus and the radiation imaging apparatus. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of the configuration of a radiation imaging system according to a first embodiment. [Figure 2] 3A to 3C are schematic diagrams illustrating a method for calculating the posture of the radiation imaging apparatus according to the first embodiment. [Figure 3] 1 is a flowchart showing the flow of an inspection according to the first embodiment. [Figure 4] 10 is a flowchart showing the flow of an inspection according to the second embodiment. [Figure 5]10 is a flowchart showing the flow of an inspection according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below through exemplary embodiments with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted. Furthermore, the term "radiation" typically refers to X-rays, but may also include alpha rays, beta rays, gamma rays, particle rays, and cosmic rays.

[0013] (First embodiment) In this embodiment, a method for accurately calculating the attitude information of a radiographic apparatus by removing the offset component of the acceleration sensor will be described, taking as an example a radiographic apparatus equipped with an acceleration sensor as an attitude measurement unit. Note that in the following description of this embodiment, an example will be described in which an acceleration sensor is used as the attitude measurement unit, but this is not limiting, and for example, a gyro sensor may also be used as the attitude measurement unit.

[0014] First, the configuration of a radiation imaging system according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the configuration of a radiation imaging system 100. The radiation imaging system 100 includes a radiation generating device 101, a radiation control device 102, a control PC 103, a radiation imaging device 104, and a peripheral device 109.

[0015] The radiation generating device 101 irradiates a subject with radiation. The radiation generating device 101 includes a tube that generates radiation, a collimator that defines the spread angle of the generated radiation beam, and a radiation dosimeter attached to the collimator.

[0016] The radiation control device 102 controls the radiation generation device 101 based on imaging conditions input by a user via the control PC 103. Before irradiating radiation by the radiation generation device 101, the radiation control device 102 transmits an exposure permission signal to the radiation imaging device 104 that irradiates radiation. Upon receiving an exposure permission response from the radiation imaging device 104 in response to the exposure permission signal, the radiation generation device 101 irradiates the radiation imaging device 104 with radiation.

[0017] The control PC 103 may be a general-purpose personal computer. That is, the control PC 103 has a general-purpose computer configured with hardware such as a CPU, a main storage device such as a DRAM, and an auxiliary storage device such as an SSD or HDD, and a general-purpose display. The user uses the control PC 103 to input imaging conditions to be instructed to the radiation control device 102 as described above, and to check the radiation image displayed on the display.

[0018] The radiation imaging device 104 has a scintillator that converts radiation into light and photoelectric conversion elements that convert the light from the scintillators arranged in a two-dimensional matrix into electric charges, and generates an image based on the irradiated radiation. The generated radiation image is transmitted to the control PC 103. The radiation imaging device 104 also transmits information about the detected radiation dose to the radiation control device 102.

[0019] The radiation imaging apparatus 104 has a control unit 105 and a posture measurement unit 106. The control unit 105 forms a radiation image by processing signals from the photoelectric conversion elements and controls the radiation imaging apparatus 104 to perform radiation imaging. The control unit 105 also has a plurality of operation modes and operates the radiation imaging apparatus 104 in an operation mode suitable for each operation flow of radiation imaging. Details of the operation modes will be described later.

[0020] The posture measurement unit 106 generates an output value by measuring information related to the posture of the radiation imaging apparatus 104. In this embodiment, the posture measurement unit 106 is a three-axis acceleration sensor, and outputs acceleration in each of the three axes (X-axis, Y-axis, and Z-axis) of a Cartesian coordinate system.

[0021] The control unit 105 has a function of calculating the attitude of the radiation imaging apparatus 104 from the output value generated by the attitude measurement unit 106. The attitude is the angle with respect to each of the three axes (X-axis, Y-axis, and Z-axis) of a Cartesian coordinate system.

[0022] The result of the attitude calculation is used to determine whether or not to correct the output value of the attitude measurement unit 106. The result of the calculation is also sent to the control PC 103 and is used to display the current attitude of the radiation imaging apparatus 104 on a display. When aligning the radiation generation apparatus 101 and the radiation imaging apparatus 104 for radiation imaging, the user can check the attitude of the radiation imaging apparatus 104 displayed on the display of the control PC 103, thereby enabling quick and highly accurate alignment.

[0023] The peripheral device 109 may be, for example, a charging device that can charge the radiation imaging apparatus 104, or an imaging table in a standing or lying position. In either form, the peripheral device 109 fixes the radiation imaging apparatus 104 in a specific position when the radiation imaging apparatus 104 is connected.

[0024] 1 illustrates an example in which the radiation generating apparatus 101 and the radiation imaging apparatus 104 are connected via a control PC 103, but this is not limiting and they may be connected via, for example, a switching hub. The radiation generating apparatus 101 and the radiation imaging apparatus 104 may be connected by wire using a cable, or may be connected wirelessly using known technology.

[0025] By connecting the radiation generating device 101 and the radiation imaging device 104, it is possible to perform synchronous imaging, in which the timing of imaging is synchronized and imaging is performed. It is also possible to perform asynchronous imaging, in which imaging is performed by detecting that radiation has been irradiated by the radiation imaging device 104 without synchronizing the two.

[0026] Next, a method for determining the attitude (angle) of the radiation imaging apparatus 104 using an acceleration sensor, which is an example of the attitude measurement unit 106, will be described with reference to Fig. 2. Fig. 2 is a schematic diagram for explaining a method for calculating the attitude (angle) of the radiation imaging apparatus 104 from the output of the acceleration sensor. In the following description, an example will be given in which two axes perpendicular to each other within the radiation irradiation surface are defined as the X-axis and Y-axis, and an axis perpendicular to the radiation irradiation surface is defined as the Z-axis, and one side of the X-ray imaging apparatus is lifted up and left stationary in a certain attitude.

[0027] When the radiation imaging device 104 is rotated around the Y axis and is then stopped so that the angle between the Z axis and gravity is θ, the following equation holds if the outputs of the X axis and Z axis of the acceleration sensor are ax and az, respectively. ax=g×sin(θ) (Equation 1) az=g×cos(θ) (Equation 2) In the formula, g represents the acceleration due to gravity.

[0028] Next, θ, which represents the attitude of the X-ray imaging device, is θ=tan -1 (ax / az) (Equation 3) It is calculated as follows.

[0029] 2(a), if the radiation imaging device 104 is placed parallel to the ground at the start of operation, gravity g is not applied in the X direction but is applied entirely in the Z direction, so the outputs ax and az of the acceleration sensor are 0g and +1g, respectively. If the radiation imaging device 104 is rotated around the Y axis from this state as shown in FIG. 2(b), the angle θ of the radiation imaging device 104 can be calculated from the values ​​of ax and az.

[0030] Here, let us consider the offset components included in the output value of the acceleration sensor. In the following explanation, the offset components of the acceleration sensor in the X-axis and Z-axis directions are referred to as ax off , a-z off We express Equation 3 as ax off , a-z off When converted into a form including the above, it becomes Equation 4 shown below. θ=tan -1 ((ax+ax off ) / az+az off ) (Equation 4)

[0031] If the true θ is 0° and the X-axis component and Z-axis component each contain an offset component of 50 mg, the outputs of the acceleration sensor will be ax = +0.05 g and az = +1.05 g, respectively, and the θ calculated using Equation 4 will be approximately 3°.

[0032] In the above, the error in the calculated angle was calculated using an example in which an offset component of 50 mg was included, but a typical acceleration sensor includes an offset component of tens to hundreds of mg. Therefore, in order to accurately determine the attitude of the radiation imaging apparatus 104, the offset component must be appropriately removed. One method for removing the offset component of the acceleration sensor is to sample the output value of the acceleration sensor multiple times, add and average it, and subtract it from the output value.

[0033] Next, an examination flow when an acceleration sensor is used as the posture measurement unit 106 of the radiation imaging apparatus 104 will be described with reference to Fig. 3. As shown in Fig. 3, the examination flow is divided into four phases: examination preparation, movement, imaging preparation, and imaging.

[0034] <Examination preparation> Before the start of an examination, the radiation imaging apparatus 104 is set in a charging device or stored in a predetermined storage location (step 301). Then, in preparation for the examination, a user such as a doctor or a medical technician sets an imaging protocol for the scheduled examination for the radiation imaging apparatus 104 to be used from the control PC 103 (step 302).

[0035] <Move> When preparation for the examination is complete, the radiation imaging device 104 to be used is taken out from the storage location and moved to the examination location (step 306). The method of transportation at this time can be carried by putting it in a pocket for carrying the radiation imaging device 104 on a medical cart, or by carrying it in the hand of the user, such as a doctor or medical technician.

[0036] <Preparing for shooting> When the radiation imaging apparatus 104 arrives at the examination location, preparations for imaging are made. Specific tasks include transitioning the radiation imaging apparatus 104 to an imaging preparation state (step 307), and aligning the radiation generating apparatus 101, the radiation imaging apparatus 104, and the subject according to the examination content (step 310).

[0037] <photograph> Once the alignment between the radiation generating device 101 and the radiation imaging device 104 is complete, the user presses the exposure switch, causing the radiation generating device 101 to irradiate the subject and the radiation imaging device 104 with radiation, thereby performing radiation imaging (step 311).

[0038] The user checks the captured images displayed on the control PC 103 to confirm that there are no problems with the imaging (step 312), and if all scheduled examinations have been completed, returns the radiation imaging device 104 to its original storage location (step 314). If the acquired images are not suitable for diagnosis or if scheduled examinations remain, the process returns to the imaging preparation phase, and the radiation generating device 101, radiation imaging device 104, and subject are realigned in preparation for the next imaging. The phases from imaging preparation to imaging are repeated in this manner until all scheduled examinations are completed.

[0039] In such an examination flow, it is in the imaging preparation phase that the user needs information on the posture of the radiation imaging apparatus 104. The posture information can be output to the screen of the control PC 103 at regular intervals, or displayed by providing an interface such as a display on the radiation generation apparatus 101, for example.

[0040] The removal of the offset component contained as an error in the posture measurement unit 106 needs to be performed when the radiation imaging apparatus 104 is stationary. In this embodiment, whether the radiation imaging apparatus 104 is stationary is determined using the operation mode of the radiation imaging apparatus 104 and the status of operations performed by the user on the radiation imaging apparatus 104.

[0041] The radiation imaging apparatus 104 has a plurality of operating modes. For example, "Power OFF" is a mode in which the radiation imaging apparatus 104 is not powered on. "Sleep" is a mode in which the radiation imaging apparatus 104 is powered on but the photoelectric conversion element is not operating. "Sleep to Ready" is a mode in which the photoelectric conversion element starts operating and is preparing for imaging. "Ready" is a mode in which the photoelectric conversion element is operating and is waiting for an exposure permission signal from the radiation control device 102. "ExpReady" is a mode in which the radiation imaging apparatus 104 has recognized the exposure permission signal from the radiation control device 102 and is ready to perform imaging.

[0042] Below, an example of a method is shown in which, in the series of inspection flows shown in FIG. 3, it is determined that the radiation imaging apparatus 104 is stationary based on the operation mode and operation status of the radiation imaging apparatus 104, and the offset component of the posture measurement unit 106 is removed.

[0043] 3, the radiation imaging apparatus 104 is stored in a predetermined storage location (for example, a charging device). Then, in step 302, an imaging protocol is set by the user. When this imaging protocol is set, the radiation imaging apparatus 104 is stationary in the predetermined storage location. At this time, the operation mode of the radiation imaging apparatus 104 is "Sleep."

[0044] That is, when the operation mode of the radiation imaging apparatus 104 is "Sleep" and the imaging protocol is set, the radiation imaging apparatus 104 is stationary. Therefore, this is the timing at which the error included in the output value of the posture measurement unit 106 can be corrected.

[0045] Therefore, in step 303, the control unit 105 determines whether or not to correct the output value of the posture measurement unit 106. This determination may be automatic, for example, by determining whether to perform correction if a certain period of time has passed since the previous correction. Alternatively, the determination may be manual, depending on whether or not the user performs a specific operation on the control PC 103 or the radiation imaging apparatus 104 after notifying the user that correction is possible. If it is determined in step 303 that correction is to be performed, the process proceeds to step 304. If correction is not to be performed, the process proceeds to step 306.

[0046] When the output value of the posture measurement unit 106 is corrected in step 304, a warning is issued to the user not to move the radiation imaging apparatus 104 during the correction. This warning is issued, for example, by displaying a message on the display of the control PC 103 or by a warning means such as an LED or speaker provided in the radiation imaging apparatus 104. Once the correction is performed, the process proceeds to step 305, where the completion of the correction is confirmed, and the process proceeds to step 306.

[0047] When the operation mode of the radiation imaging apparatus 104 becomes Ready in step 307, the acceleration sensor serving as the attitude measurement unit 106 acquires a value, which is calculated by the control unit 105 (step 308), and the attitude information is output and displayed (step 309). Based on the attitude information of the radiation imaging apparatus 104 displayed on the control PC 103 or the like, the user aligns the radiation generation apparatus 101 and the radiation imaging apparatus 104 (step 310).

[0048] After the alignment is complete, the user presses the exposure switch, and the operation mode of the radiation imaging apparatus 104 becomes ExpReady, which is a state in which radiation exposure is possible. Next, radiation is irradiated from the radiation generation device 101 to the radiation imaging apparatus 104, and a radiographic image is captured (step 311). When the imaging is completed, the operation mode of the radiation imaging apparatus 104 switches to the Ready state. Since the radiation imaging apparatus 104 is still stationary even immediately after this imaging, it is possible to correct the output value of the posture measurement unit 106, and therefore the operations of steps 303 to 305 described above may be performed.

[0049] The captured image is transferred to the control PC 103 and displayed on the display, and the user can check the radiation image. If the output value of the posture measurement unit 106 has been corrected, this may be done in parallel with checking the captured image. After checking the image, a determination is made in step 313 as to whether the examination is complete. If all scheduled protocols have been completed, the X-ray imaging device is moved to a storage location in step 314, and the series of examination flows ends. If any protocols remain, steps 308 to 313 are repeated until all protocols are completed.

[0050] As described above, in this embodiment, the posture measurement unit 106 corrects the output value of the posture measurement unit 106 in accordance with the status of the operation of radiation imaging. The correction is performed when the radiation imaging apparatus 104 is stationary. Whether the radiation imaging apparatus 104 is stationary is determined by the control unit 105 detecting the operation mode of the radiation imaging apparatus 104 held by the control unit 105 and the status of the operation performed on the radiation imaging apparatus 104.

[0051] For example, in the imaging preparation phase, the output value of the posture measurement unit 106 can be corrected when the radiation imaging apparatus 104 is in a sleep state and a protocol is set as a trigger. Also, in the imaging phase, the correction can be performed when the imaging is completed and the operation mode of the radiation imaging apparatus 104 is switched from ExpReady to Ready as a trigger.

[0052] The correction of the output value of the posture measurement unit 106 may be performed automatically based on the determination by the control unit 105. Alternatively, the control unit 105 may notify the user that it has determined that the correction is possible, and the user may decide whether or not to perform the correction, and may perform the correction manually by operating an input means such as the control PC 103.

[0053] Furthermore, it is known that the offset component included as an error in the orientation measurement unit 106 varies depending on the usage environment; for example, the offset component varies due to the influence of temperature. The usage environment of the radiation imaging apparatus 104 is diverse, and even if the output value of the orientation measurement unit 106 is corrected at the time of shipment from the factory, the temperature may differ from the environment in which the apparatus is actually used, such as a hospital. Furthermore, even if the correction is performed when the apparatus is introduced into a hospital, the temperature at that time may differ from the temperature at the time of use. Even a slight difference in the environment can deteriorate the accuracy of the calculated orientation information, so the correction must be performed under conditions as close as possible to the environment in which the orientation information will actually be used.

[0054] In this embodiment, by correcting the output value of the orientation measurement unit 106 at any of the timings described above, the correction can be performed in an environment close to the actual usage environment, thereby suppressing the influence of offset components contained as errors in the output value of the orientation measurement unit 106. This allows the orientation information of the radiation imaging apparatus 104 to be calculated with high precision, allowing the user to align the radiation generation apparatus 101 and the radiation imaging apparatus 104 with high precision.

[0055] In this embodiment, the timing for correcting the output value of the posture measurement unit 106 is described as immediately after the imaging protocol is set and immediately after the radiographic image is acquired, but this is not limitative. The output value of the posture measurement unit 106 may be corrected at other times as long as the radiographic apparatus 104 is stationary.

[0056] (Second embodiment) In this embodiment, an example will be described in which the output value of the orientation measurement unit 106 is used to determine whether or not to correct the output value of the orientation measurement unit 106.

[0057] When a three-axis acceleration sensor is used as the posture measurement unit 106, the output value of each axis of the acceleration sensor is a constant value when the radiation imaging apparatus 104 is stationary. Two methods will be described below as examples of methods for determining whether the radiation imaging apparatus 104 is stationary.

[0058] The first method is to use the change over time (differential value Δa) of the output value a of the orientation measurement unit 106. The orientation measurement unit 106 transmits the output value a to the control unit 105. The control unit 105 calculates the change over time of the output value a (differential value Δa) and compares Δa with a threshold value th1. If Δa is smaller than the threshold value th1, it can be determined that the radiation imaging apparatus 104 is stationary. In this case, the output value of the orientation measurement unit 106 is corrected based on the following equation 5. aout=a―Δa (Equation 5)

[0059] As shown in Equation 5, by subtracting the differential value Δa, which is the time change of the output value a of the posture measurement unit 106, from the output value a, it is possible to obtain the output value aout from which the time-varying component has been removed.

[0060] The second method is to store the orientation a0 of the radiation imaging apparatus 104 at a certain point in time in the control unit 105 in advance, and use this to determine whether the radiation imaging apparatus 104 is stationary. The control unit 105 compares the output value a acquired by the orientation measurement unit 106 with the orientation a0 stored in the control unit 105, and if the difference between the two is smaller than a threshold value th2, it is determined that the orientation of the radiation imaging apparatus 104 has not changed from the orientation a0.

[0061] Furthermore, if the control unit 105 determines that the change over time in the output value a of the orientation measurement unit 106 (differential value Δa) has become smaller than the threshold value th1, it can be determined that the radiation imaging apparatus 104 has not changed its orientation from the previously held orientation and is stationary. By correcting the output value of the orientation measurement unit 106 based on the following equation 6, it is possible to obtain an output value aout from which not only the time-varying components but also the time-invariant components have been removed. aout=a0 (Formula 6)

[0062] Furthermore, if the control unit 105 stores various states in which the radiation imaging device 104 is stationary, such as when the radiation imaging device 104 is upright, lying down, or placed in the pocket of a medical cart, as postures a0, the offset component contained in the acceleration output value can be accurately removed.

[0063] Fig. 4 shows the inspection flow in this embodiment, and explanations of the same parts as in Fig. 3 will be omitted.

[0064] Steps 401 and 402 are the same as steps 301 and 302 in Fig. 3. Immediately after the imaging protocol is set in step 402 in Fig. 3, the operation mode of the radiation imaging apparatus 104 is Sleep, and the radiation imaging apparatus 104 is stationary. At this time, in the next step 415, the output value a of the posture measurement unit 106 is confirmed. This ensures that the radiation imaging apparatus 104 is stationary during correction.

[0065] If it is determined in step 415 that the radiation imaging apparatus is stationary, the process proceeds to determining whether or not to perform correction in step 403. If it is determined in step 415 that the radiation imaging apparatus is not stationary, the process proceeds to step 406 without proceeding to determining whether or not to perform correction.

[0066] Steps 403 to 411 for capturing a radiographic image are the same as steps 303 to 311 described with reference to FIG. 3, and therefore a description thereof will be omitted.

[0067] A radiation image is captured in step 411, and when the capture is completed, the radiation imaging apparatus switches to the Ready state. Since the radiation imaging apparatus is still stationary even immediately after this capture, the output value of the posture measurement unit 106 described above is confirmed in step 415.

[0068] If it is determined by the method described above that the radiation imaging apparatus is stationary, the process proceeds to step 403 to determine whether or not to perform correction, and if it is determined that the radiation imaging apparatus is not stationary, correction is not performed and the process proceeds to image confirmation in step 412. Steps 412 and after are the same as steps 312 and after in the first embodiment, and therefore a description thereof will be omitted.

[0069] According to the imaging flow described above, when it is detected from the output value of the orientation measurement unit 106 that the radiation imaging apparatus is stationary, the output value of the orientation measurement unit 106 is corrected. This makes it possible to suppress the influence of offset components contained as errors in the output value of the orientation measurement unit 106. By suppressing the influence of the offset components, it is possible to accurately calculate the orientation information of the radiation imaging apparatus 104, and therefore the user can accurately align the radiation generation apparatus 101 and the radiation imaging apparatus 104.

[0070] In this embodiment, as in the first embodiment, the timing for determining whether to correct the output value of the posture measurement unit 106 is immediately after the imaging protocol is set and immediately after the radiographic image is acquired, but the timing for performing the correction is not limited to this. The correction may be performed at any time as long as the radiographic apparatus 104 is stationary.

[0071] (Third embodiment) In this embodiment, a method of integrating the output of the orientation measurement unit 106 to calculate the amount of displacement from a reference position and determining the position of the radiation imaging apparatus 104 and the distance between the radiation generation apparatus 101 and the radiation imaging apparatus 104 will be described.

[0072] As in the first and second embodiments, it is assumed that a three-axis acceleration sensor is mounted as an attitude measurement unit in the radiation imaging apparatus 104. A method for calculating the position of the radiation imaging apparatus 104 using the acceleration sensor will be described below.

[0073] The velocity v(t) at time t can be calculated by integrating the output value a(t) of one axis of the acceleration sensor at time t from t=0 with a time interval Δt and the number of data acquisitions n (t=nΔt) up to a(t). If the initial value of the velocity at t=0 is v(0), it can be expressed by the following equation 7. v(t)=v(0)+Σa(kΔt)Δt(k=1~n) (Equation 7)

[0074] Furthermore, the position x(t) at time t can be expressed by the following equation 8, where the initial value of the position at t=0 is x(0). x(t)=x(0)+Σv(kΔt)Δt(k=1~n) (Equation 8)

[0075] In order to improve the calculation accuracy, known numerical integration methods (trapezoidal rule or Simpson's rule) may be used.

[0076] The relative position from the initial position of the radiation imaging device is calculated using the method described above. In this embodiment, the initial position of the radiation imaging device is set to the storage location in the examination room (specifically, the state where it is connected to the charging device as a peripheral device in FIG. 1). Furthermore, if the radiation generating device (near the tube) also has a means for acquiring the amount of tube movement, the position of the tube in the examination room can be calculated in the same way.

[0077] The amount of movement of the tube may be obtained by mounting an acceleration sensor, as in the case of a radiographic imaging device, and calculating the position from the output of the acceleration sensor. Alternatively, the amount of movement may be calculated from the displacement of a rail along which the radiation generating device 101 fixed in a room runs, or from the displacement of a motor that extends and retracts the tube.

[0078] Generally, the positions of the charging device and the radiation generating device of the radiography device do not change, so the absolute coordinates of both devices within the examination room can be considered known. Therefore, the absolute coordinates within the room can be calculated from the relative positions of the radiography device and the tube from their respective initial positions.

[0079] As mentioned above, when calculating the position of the radiography device, numerical integration is required. In numerical integration, the output values ​​of the acceleration sensor are added up over the data acquisition time, so when calculating the position information, the offset component included in the acceleration sensor output will be affected by errors.

[0080] Next, a series of inspection flows from calculating position information from the acceleration sensor output, aligning the radiation imaging device with the radiation generation device, and performing radiation imaging will be described with reference to Fig. 5. Explanations of parts that overlap with those in the first and second embodiments will be omitted.

[0081] The state in which the radiography device is stored in the charging device in step 501 is set as the initial position. Data acquisition by the acceleration sensor starts at the timing when the protocol is set in step 502 (step 516). Next, a determination is made as to whether correction should be performed in step 503, but this has already been explained in the first and second embodiments, so a detailed description is omitted. Thereafter, the radiography device moves and preparations for imaging are made.

[0082] In the first and second embodiments, a method of outputting angle information of the radiation imaging apparatus 104 for alignment has been described. In this embodiment, however, the amount of movement (coordinates) from the initial position is output to align the radiation generation apparatus 101 with the radiation generation apparatus 101. As a method of alignment, mutual position information (coordinates) may be output to a control PC to determine the distance between the radiation generation apparatus 101 and the radiation imaging apparatus 104, and the positions may be adjusted manually. It is also possible to provide the radiation generation apparatus 101 with a mechanism that can automatically move the tube, and automatically align the radiation generation apparatus 101 so that the tube position is appropriately aligned to match the arrangement (coordinates) of the radiation imaging apparatus 104.

[0083] Furthermore, in order to arrange the radiation generation device and the radiation imaging device at a desired angle after adjusting the positions (distance) of them, the information displayed on the control PC or the like may be switched from coordinate information to angle information.

[0084] Once the alignment in step 510 is complete, the radiographic image is acquired in step 511, followed by a decision as to whether correction should be performed (step 503), image confirmation (step 512), and the end of the examination (step 513).

[0085] When all the examinations are completed, the acquisition of posture information by the acceleration sensor is terminated (step 17), and the radiation imaging apparatus is returned to its storage location (step 514), thereby completing the series of examinations.

[0086] If the output value of the orientation measurement unit 106 is corrected at any of the timings described above, the offset component contained in the output of the acceleration sensor can be removed, improving the accuracy of calculating position information using the output of the acceleration sensor.

[0087] Note that the acceleration sensor continues to acquire posture information from the preparation for the examination until the end of the examination, and therefore the calculation load for calculating the position information is heavier than in Embodiments 1 and 2. Therefore, the calculation of the position information may be performed on the control PC 103 in addition to being performed on a calculation unit in the radiation imaging apparatus.

[0088] Furthermore, there are cases where the offset component included in the data changes before and after correction of the output value of the orientation measurement unit 106. Therefore, in order to further improve the calculation accuracy of the position information, processing to reduce the offset component may be performed on the calculation unit or the control PC 103 even for the output data before correction when calculating the position information.

[0089] (Other embodiments) The present invention can also be realized by supplying a program that achieves the above-mentioned functions to a system or device via a network or storage medium, and having one or more processors in the computer of that system or device read and execute the program.

[0090] Furthermore, various recording media can be used, such as flexible disks, optical disks (e.g., CD-ROMs, DVD-ROMs), magneto-optical disks, magnetic tapes, non-volatile memories (e.g., USB memories), ROMs, etc. Furthermore, the programs that implement the above-described functions may be downloaded via a network and executed by a computer.

[0091] Furthermore, the functions of the above-described embodiments are not limited to being realized only by a computer reading and executing the program code, but also include cases where an operating system (OS) running on a computer performs some or all of the actual processing based on instructions from the program code, thereby realizing the functions of the above-described embodiments.

[0092] Furthermore, the program code read from the recording medium may be written to a memory provided on a function expansion board inserted into a computer or a function expansion unit connected to the computer, and the CPU or the like provided on the function expansion board or function expansion unit may perform some or all of the actual processing based on the instructions of the program code, thereby realizing the above-mentioned functions. [Explanation of symbols]

[0093] 100 Radiography System 104 Radiography equipment 105 Control Unit 106 Posture measurement unit

Claims

1. A radiographic imaging device for acquiring a radiographic image based on radiation, comprising: an attitude measurement unit that measures the attitude of the radiation imaging apparatus; a posture measurement unit that checks an output value related to posture based on input of an imaging protocol setting, and performs offset correction of the output value of the posture measurement unit based on confirmation of an output value corresponding to a state in which the radiation imaging device is stationary.

2. The posture measurement unit removes an offset component by the offset correction.

2. The radiographic imaging apparatus according to claim 1, wherein:

3. The posture measurement unit checks the output value when the radiation imaging device is switched to a state in which the photoelectric conversion element is in a driving state and an exposure permission signal can be received after the radiation imaging device is exposed to radiation and a radiation image is captured, and when it is detected that the radiation imaging device is stationary based on the checked output value, performs further offset correction of the posture measurement unit.

3. The radiographic imaging apparatus according to claim 2, wherein:

4. The radiation imaging device has a plurality of operating modes that differ in whether or not the photoelectric conversion element is driven, The posture measurement unit determines whether to perform the offset correction based on whether the current operation mode is a predetermined operation mode among the plurality of operation modes.

4. The radiographic imaging apparatus according to claim 3, wherein:

5. A radiographic imaging device for acquiring a radiographic image based on radiation, comprising: a photoelectric conversion element that converts light based on radiation into electric charges; an attitude measurement unit that measures the attitude of the radiation imaging apparatus, The posture measurement unit performs offset correction of the output value of the posture measurement unit in response to input of a setting of an imaging protocol while the photoelectric conversion element is not being driven. A radiographic imaging device characterized by:

6. A radiographic apparatus for acquiring a radiographic image based on radiation, comprising: a photoelectric conversion element that converts light based on radiation into electric charges; an attitude measurement unit that measures the attitude of the radiation imaging apparatus, the posture measurement unit performs offset correction of the output value of the posture measurement unit in response to the photoelectric conversion element being switched to a state in which it is driven and can accept an exposure permission signal after the radiation imaging device is irradiated with radiation and a radiation image is captured. A radiographic imaging device characterized by:

7. 3. The radiation imaging apparatus according to claim 2, wherein the posture measurement unit performs the offset correction when it is detected from the output value that the radiation imaging apparatus is stationary and a predetermined time has elapsed since the previous offset correction.

8. The posture measurement unit performs the offset correction in response to a differential value of the output value being smaller than a predetermined threshold value.

8. The radiographic imaging apparatus according to claim 7, wherein:

9. 9. The radiation imaging apparatus according to claim 8, wherein the posture measurement unit performs the offset correction by subtracting the differential value from the output value.

10. The posture measurement unit performs the offset correction based on a known posture when the radiation imaging apparatus is fixed at a predetermined position, which is stored in advance, and a current posture of the radiation imaging apparatus.

3. The radiographic imaging apparatus according to claim 2, wherein:

11. The posture measurement unit performs the offset correction when it is detected that the radiation imaging apparatus is stationary from the known posture and the current posture.

11. The radiographic imaging apparatus according to claim 10,

12. Having a control unit, The radiation imaging apparatus according to claim 10 , wherein the control unit calculates a movement amount of the radiation imaging apparatus from the known orientation based on the known orientation and the output value.

13. The radiographic imaging apparatus according to any one of claims 1 to 12, a radiation generating device that irradiates the radiation imaging device with radiation in order to perform radiation imaging; A radiation imaging system comprising:

14. a measuring step of measuring the attitude of the radiation imaging apparatus using an attitude measuring unit; a correction step of checking an output value of the posture measurement unit based on input of an imaging protocol setting, and offset-correcting the output value of the posture measurement unit based on confirmation of an output value corresponding to a state in which the radiation imaging apparatus is stationary. A method for controlling a radiation imaging apparatus, comprising:

15. In the correction step, after the radiation imaging device is irradiated with radiation and a radiation image is captured, the output value is confirmed when the photoelectric conversion element is switched to a state in which it is in a driving state and can accept an exposure permission signal, and if it is detected based on the confirmed output value that the radiation imaging device is stationary, further offset correction is performed on the attitude measurement unit.

15. The method for controlling a radiation imaging apparatus according to claim 14,

16. A program for causing a computer to execute the control method according to claim 15.

17. A computer-readable recording medium on which the program according to claim 16 is recorded.

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