JP6257177B2 - X-ray imaging apparatus and method for controlling X-ray imaging apparatus - Google Patents

Description

The present invention, X-ray imaging apparatus, and a control how the X-ray imaging apparatus.

  In recent years, in X-ray imaging for medical diagnosis, digital imaging apparatuses that perform imaging using an imaging unit using a photoelectric conversion element (conversion element) have become widespread. The digital photographing apparatus is excellent in that it can obtain an X-ray transmission image without developing a film or the like, has immediacy, and can perform image processing.

  In a conventional digital X-ray imaging apparatus, an imaging unit and an X-ray generation unit are connected using a dedicated line, so that not only power and image information but also driving between the imaging unit and the X-ray generation unit and X Line generation timing signals are also communicated. For example, in a digital X-ray imaging apparatus, communication is performed between an X-ray generation unit and an imaging unit, and imaging is performed in accordance with the X-ray generation timing of the X-ray generation unit and the imaging timing of the imaging unit. It is. In recent years, in order to simplify the configuration required for communication, a digital X-ray imaging apparatus has been developed that performs imaging immediately after detecting radiation and does not communicate between the X-ray generation unit and the imaging unit. Yes.

  In Patent Document 1, the X-ray generation unit emits X-rays at a time when exposure is permitted, and the X-ray imaging unit receives an image of the X-ray generation signal, and then an image based on charges accumulated after a fixed accumulation time. A configuration for reading out is disclosed. Patent Document 2 discloses a technique for changing the driving method according to whether the connection state between the X-ray imaging unit and the X-ray generator is a dedicated line or other than a dedicated line.

JP-A-2005-46203 Japanese Patent Application No. 2008-201430

  As described above, when the method of reading an image after a fixed accumulation time without applying communication between the X-ray generator and the imaging unit is applied, the inclusive relationship between the X-ray irradiation time and the image accumulation time is communicated between the two. Different from the case of doing. For this reason, there is a possibility that an image is accumulated for a long time even after the end of X-ray irradiation in the X-ray generation unit. In addition, although the X-ray generation unit emits X-rays, the imaging unit may end the accumulation of image signals. In this case, there is a possibility that the image data based on the charge accumulated in the conversion element is not properly imaged.

  The present invention has been made in view of the above problems, and sets the driving method of the imaging unit according to the connection state between the X-ray generation unit and the X-ray imaging unit and the X-ray detection setting of the imaging unit. An object of the present invention is to provide an X-ray imaging technique that can be used.

An X-ray imaging apparatus according to one aspect of the present invention that achieves the above object comprises: an X-ray imaging means having an image imaging means for imaging an X-ray image generated from the X- ray generation means; An image photographing apparatus, wherein the X-ray photographing means comprises:
A determination unit that determines whether or not communication is performed between the X-ray generation unit and the X-ray imaging unit to synchronize the timing of X-ray generation and the drive timing of the X-ray imaging unit;
In response to the determination, the image capturing unit is driven so that an accumulation time when the asynchronous communication without the synchronized communication is performed is shorter than an accumulation time when the synchronized communication is performed. A setting means for setting a method;
It is characterized by providing.

An X-ray imaging apparatus according to one aspect of the present invention that achieves the above object includes an X-ray generating means for generating X-rays, and an X-ray imaging means having an image capturing means for capturing the X-ray image; An X-ray imaging apparatus having the X-ray imaging means,
Output means for outputting a signal indicating that the X-ray imaging means is irradiated with X-rays;
Setting means for setting a driving method of the image photographing means according to the signal;
It is characterized by providing.

  According to the present invention, it is possible to set the driving method of the image photographing unit according to the connection state between the X-ray generation unit and the X-ray photographing unit and the X-ray detection setting of the photographing unit. Thereby, it is possible to appropriately use the X-ray transmission signal irradiated to the subject for imaging.

1 is a block diagram of an X-ray imaging apparatus according to a first embodiment. 6 is a timing chart of a conventional X-ray imaging apparatus. 3 is a timing chart of the X-ray imaging apparatus of the first embodiment. The figure which shows the flow of operation | movement of the X-ray imaging device of 1st Embodiment. The figure explaining the operation | movement sequence of the conventional X-ray imaging apparatus. The figure explaining the operation | movement sequence of the X-ray image imaging device of 1st Embodiment. The figure which illustrates the structure of an operation panel. Explanatory drawing of the discrete wave red transformation and inverse transformation of a noise reduction process. The figure explaining the operation | movement sequence of the X-ray image imaging device of 2nd Embodiment. The figure which shows the flow of operation | movement of the X-ray imaging device of 2nd Embodiment. The figure which illustrates the X-ray imaging system which has X-ray imaging apparatus. The figure which shows X-ray image imaging operation | movement which displays the image after X-ray image imaging. The timing chart which detects the radiation irradiation start and acquires a picked-up image.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in the embodiments are merely examples, and the technical scope of the present invention is determined by the claims, and is not limited by the following individual embodiments. .

(First embodiment)
FIG. 1 is a block diagram illustrating an overall functional configuration of an X-ray imaging apparatus according to the first embodiment of the present invention. An X-ray generation unit 1 that generates X-rays and an X-ray imaging unit 10 that receives X-rays transmitted through the subject P are disposed to face each other.

  Inside the X-ray generator 1, a generator 2 that generates X-rays is provided, and this generator 2 is connected to an X-ray generation controller 3. The X-ray generation control unit 3 is connected to the X-ray generation control unit 3 via the bus 4 by a plurality of communication connections, including a wireless communication connection unit 5 for performing wireless communication with the X-ray imaging unit 10 and a wired communication connection unit 6 for performing wired communication. Are connected to each other. An operation unit 7 for operating the X-ray generation unit 1 is connected to the X-ray generation unit 1 via a bus 4.

  The X-ray imaging unit 10 includes a two-dimensional X-ray imaging unit 11 that receives X-rays transmitted through the subject P. The two-dimensional X-ray image capturing unit 11 has a sensor array in which a plurality of photoelectric conversion elements (conversion elements) that convert X-rays (radiation) into image signal charges (electrical signals) are two-dimensionally arranged. The two-dimensional X-ray image capturing unit 11 transmits an image obtained by the A / D conversion unit 13, the amplification unit 14, the data collection unit 15 that collects imaging data, and the data collection unit 15 via the CPU bus 12. A pre-processing unit 16 for processing is connected. The CPU bus 12 is connected to an image processing unit 17, a storage unit 18 for storing images, a CPU 19, a main memory 20, an operation panel 21, an image display unit 22, and a driving method setting unit 23. In addition, a driving method table switching determination unit 24 is connected to the CPU bus 12.

  Further, a wireless communication connection unit 26 for communicating with the X-ray generation unit 1, a plurality of communication connection units of a wired communication connection unit 27, and a synchronization signal presence / absence detection unit 28 are connected to the CPU bus 12.

  The main memory 20 stores various data necessary for processing in the CPU 19 and functions as a working memory for the CPU 19. Further, the CPU 19 uses the main memory 20 to perform operation control of the entire X-ray imaging apparatus according to the operation of the operation panel 21.

  The X-ray imaging unit 10 is connected to the wireless communication connection unit 5 or the wired communication connection unit 6 of the X-ray generation unit 1 via the wireless communication connection unit 26 or the wired communication connection unit 27 every predetermined time, for example, every 10 minutes. It is possible to perform communication and to display a communication connection unit when photographing is performed on the operation panel 21. At this time, when communication is not connected between the X-ray imaging unit 10 and the X-ray generation unit 1, that is, when a synchronization signal is not exchanged, the operation panel 21 displays that the connection is not synchronized. . When an operator inputs a shooting instruction via the operation panel 21, the contents of the shooting instruction are stored in the storage unit 18 and displayed on the operation panel 21.

  When the communication connection unit is neither a wireless communication connection unit nor a wired connection unit, the synchronization signal presence / absence detection unit 28 detects a state where there is no synchronization signal.

  Further, the operator selects a specific imaging region from the imaging region selection unit 37 via the operation panel 21 when an imaging instruction is given. The photographing instruction is transmitted to the driving method setting unit 23 by the CPU 19 via the CPU bus 12. When the driving method setting unit 23 receives the photographing instruction, the driving method is changed via the driving method table switching determination unit 24.

  After that, when the operator gives an instruction for X-ray generation (irradiation) using the operation unit 7 of the X-ray generation unit 1, the X-ray generation unit 1 controls the generation unit 2 via the X-ray generation control unit 3. X-ray imaging is performed by irradiating X-rays.

  In this X-ray imaging, the X-rays irradiated from the generation unit 2 pass through the subject P while being attenuated and reach the two-dimensional X-ray image imaging unit 11. When the synchronization signal is not exchanged (communication), a signal for reading whether the X-ray imaging means of the two-dimensional X-ray image imaging unit 11 is irradiated with X-rays is detected. For example, a bias signal (Vs signal) of the imaging unit is used as a signal for reading whether the X-ray imaging unit is irradiated with X-rays. A minute current flowing in the bias line is detected, and the bias signal determination unit 25 determines whether or not X-rays have been irradiated. When it is determined that X-rays have been irradiated, the two-dimensional X-ray imaging unit 11 immediately interrupts the reset operation and starts the accumulation operation. The image signal stored in each pixel is read and scanned by the two-dimensional X-ray image capturing unit 11 and an X-ray image signal is output. In the present embodiment, the subject P is, for example, a human body, and the X-ray image output from the two-dimensional X-ray image capturing unit 11 is a human body image.

  The X-ray image signal output from the two-dimensional X-ray image capturing unit 11 is converted into a predetermined digital signal by the A / D conversion unit 13 and transferred to the preprocessing unit 16 as X-ray image data. The preprocessing unit 16 mainly corrects the characteristics of the X-ray imaging apparatus, and corrects, for example, variations in sensitivity of each pixel of the two-dimensional X-ray imaging unit 11 with respect to the above-described X-ray image data. Gain correction processing to be performed, and dark current correction processing to correct variations in dark current for each pixel. The preprocessing unit 16 stores a correction image (for example, a correction gain correction image and a dark current correction image) in the main memory 20 before the operator performs X-ray imaging, and corrects the correction image as necessary during correction. Read out the image. The captured image is required to be displayed and output as soon as possible so that a radiographer or the like can confirm whether the target has been captured. For this reason, first, a thinned image is displayed first, and a high-definition image is displayed step by step.

  Then, the X-ray image data subjected to these pre-processing is transferred as original image data to the main memory 20 and the image processing unit 17 through the CPU bus 12 under the control of the CPU 19. The main memory 20 stores the X-ray image data (original image data) transferred from the preprocessing unit 16. The image processing unit 17 performs noise reduction processing, frequency processing, monitoring, and monitoring for making X-ray image data (original image data) whose characteristics of the X-ray imaging apparatus have been corrected easier to see information that the doctor wants to observe. Image processing such as gradation processing according to a display medium such as a film is performed. Then, after executing the image processing, the image processing unit 17 outputs the X-ray image data after the image processing to the image display unit 22. The image processing unit 17 performs similar image processing on the X-ray image data (original image data) stored in the main memory 20. The X-ray image data after the image processing is output to the image display unit 22.

  FIG. 2 is a timing chart of X-ray imaging by a conventional X-ray imaging apparatus, and FIG. 3 is a timing chart of X-ray imaging by the X-ray imaging apparatus according to the present embodiment. The time (Acumulate ON time) from when charges are accumulated in the two-dimensional X-ray image capturing unit to when they are read is defined as an image accumulation time T. As shown in FIG. 2A, in the X-ray imaging by the X-ray imaging apparatus, the X-ray delay time Δt and the X-ray irradiation time X (X_ON time) fall within the image accumulation time T. In this way, the timing of X-ray imaging is set.

  However, if the connection method between the X-ray generation unit 1 and the X-ray imaging unit 10 is different, not only the normal X-ray delay time Δt but also communication retry (communication retry) as shown in FIG. There is also a possibility that a delay time Δt ′ due to. Here, X-ray delay time Δt + delay time Δt ′ is ΔT. In this case, as shown in FIG. 2B, the delay time Δt ′ due to the communication retry or the like becomes longer, so that the X-ray is irradiated within the image accumulation time T in spite of the X-ray irradiation. The image accumulation time T ends in the middle of X-ray irradiation without completing the beam irradiation. In such a case, there is a possibility that desired X-ray image data cannot be obtained.

  With respect to such a conventional problem, in the present embodiment, a signal (CNN_CHK,) for determining a connection state in advance between the X-ray generation unit 1 and the X-ray imaging unit 10 as shown in FIG. CNN_RET). Here, the synchronization signal presence / absence detection unit 28 transmits a determination signal (CNN_CHK) for determining a connection state between the X-ray generation unit 1 and the X-ray imaging unit 10 to the X-ray generation unit 1. When communication between the X-ray generation unit 1 and the X-ray imaging unit 10 is established, at least one of the wired communication connection unit 6 and the wireless communication connection unit 5 of the X-ray generation unit 1 receives a determination signal (CNN_CHK). ) Is transmitted to the X-ray imaging unit 10 side in response to the response signal (CNN_RET).

  In the present embodiment, the X-ray imaging unit 10 has a table for changing the image accumulation time T according to the detected connection state. The driving method setting unit 23 selects a table according to the connection state. The image accumulation time T varies depending on the imaging region selected by the imaging region selection unit 37 (FIG. 7), and the driving method setting unit 23 selects a table corresponding to the connection state and selects the image accumulation time. Change T.

  For example, when there is no connection state, that is, asynchronous, there is a possibility that the delay time Δt ′ due to communication retry or the like becomes long depending on the external environment. Even if the delay time Δt ′ caused by such a connection state occurs, the drive method setting unit 23 changes the image storage time T including the margin time according to the connection state, so that the image storage time T is reduced. It is possible to suppress the possibility that the accumulation time becomes excessively long due to the long length. That is, it is possible to solve the problem of the conventional X-ray imaging apparatus in which the X-ray irradiation is not completed within the image storage time T and the image storage time T ends during the X-ray irradiation.

When radiation irradiation starts, the dose of radiation does not rise instantaneously, and if the rise of the dose is gradual, there may be a delay before reaching a predetermined dose. In addition, the time until the bias signal determination unit 25 of the imaging unit 11 detects that X-ray irradiation has occurred is also a factor of delay. This delay is shown as a delay time (Δt ^k ) in the timing chart of FIG. Assuming that the X-ray irradiation start timing is T1, the driving method setting unit 23 sets the two-dimensional X-ray so that the charge accumulation start timing T2 of the two-dimensional X-ray imaging unit 11 comes after the delay time (Δt ^k ) has elapsed. The timing of the start of charge accumulation in the image photographing unit 11 is controlled. By controlling the timing as described above, it becomes possible to perform imaging while the radiation dose is stable, and within the image accumulation time T even if the image accumulation time T is not set longer than necessary. It becomes possible to complete the irradiation of the line. That can be shortened than the accumulation time that has been set by the amount of Delta] t ^k.

  Here, the driving method setting unit 23 (image accumulation time control unit) controls the image accumulation time T, but it goes without saying that the shooting mode may be changed. The driving method setting unit 23 sets the imaging mode of the two-dimensional X-ray image capturing unit 11 in the asynchronous connection state to an imaging mode with a shorter accumulation time than the imaging mode of the two-dimensional X-ray image capturing unit 11 in the synchronized connection state. The driving method of the two-dimensional X-ray image capturing unit 11 is changed. For example, the drive method setting unit 23 sets the sensitivity mode of the X-ray automatic detection unit, the short-time shooting mode for still images (short-time accumulation time mode), and the continuous imaging mode with a short accumulation time. By this selection, the imaging mode of the two-dimensional X-ray imaging unit 11 is changed, and the same effect can be obtained in that the image accumulation time changes according to the changed imaging mode.

  The driving method setting unit 23 of the X-ray imaging apparatus according to the present embodiment determines the connection state as described above, and displays the current connection state on the operation panel 21 as a result of the determination. For example, the operation panel 21 displays that the communication state between the X-ray generation unit 1 and the X-ray imaging unit 10 is established or that the communication state is not established. By displaying in this way, the operator can check the connection state, and can detect the presence or absence of a synchronization signal between the X-ray generator and the X-ray control unit, and suppress an increase in useless accumulation time. Become.

  In order to ensure that an image is always accumulated during X-ray irradiation, a solution method for making the normal image accumulation time T longer is conceivable. However, as the image accumulation time T increases, the dark current mainly Noise called noise increases. The X-ray imaging apparatus proposed in the present invention suppresses noise and reduces the image display time by shortening the image accumulation time T by the time used for detection by automatic X-ray detection when there is no synchronization signal. Fast X-ray equipment. In addition, since the image can be sent to the display unit 22 earlier, the immediacy of the image capturing unit 11 is increased.

  Here, the two-dimensional X-ray imaging unit 11 includes a sensor array including a plurality of conversion elements that convert radiation into image signal charges (electric signals) and switch elements such as TFTs that transfer the electric signals to the outside. Have. As the image accumulation time T increases, the difference in the TFT readout time in the two-dimensional X-ray imaging unit 11 may become obvious, and the shading amount increases. Normally, in the two-dimensional X-ray image photographing unit 11 using a photoelectric conversion element, the variation in dark current noise increases as the image accumulation time T becomes longer. It is necessary to shorten T. In the description of the present embodiment, the image accumulation time T is used, but it goes without saying that the image accumulation end time or the signal readout start time is also used in the same meaning.

  FIG. 4 is a diagram showing a flow of X-ray imaging performed by the X-ray imaging apparatus according to the present embodiment. First, in step S <b> 1, the synchronization signal presence / absence detection unit 28 detects a connection state by detecting the presence / absence of a synchronization signal between the X-ray generation unit 1 and the X-ray imaging unit 10. When a wireless communication connection or a wired communication connection is made simply, a method of detecting that there is a synchronization signal, or a method of checking in a simulated manner can be used. For example, the presence or absence of the synchronization signal can be detected by outputting a synchronization signal from the X-ray imaging unit 10 and detecting whether or not the synchronization signal returns from the X-ray generation unit 1 within a predetermined time. The timing for detecting the connection state is preferably performed immediately before shooting for each shooting, but if the connection state is acquired for each shooting, the time required for one shooting increases. For example, in a facility where patients visit one after another for medical examinations and the like, it is wasteful to check the connection state for each imaging even when the connection state hardly changes.

  Therefore, in such a shooting application, it is possible to switch so as to check the connection state not for every shooting but for every series and every fixed time, for example, when shooting for the first time after turning on the power, or every fixed time For example, the connection state may be periodically checked every 10 minutes. When there is a button that can change the synchronous / asynchronous connection method on the operation panel 21, the connection state may be checked when the button is pressed, and when the synchronous connection is not possible, the operation panel 21 may display the connection state. In addition, since it is necessary for the X-ray imaging unit 10 to recognize the presence or absence of X-ray irradiation at the time of asynchronous, the fact that it is asynchronous is displayed on the operation panel 21 or the image display unit 22 to notify the user.

  Next, in the determination in step S2, the flow after the next step is branched depending on whether there is a synchronization signal using the connection detection information detected in step S1. If it is determined that there is a wired / wireless connection and there is a synchronization signal, the process proceeds to step S3 for starting shooting without changing the default drive timing. When there is a synchronization signal and the X-ray generation unit 1 and the X-ray imaging unit 10 are in a synchronized connection state, the driving method setting unit 23 performs communication between the X-ray generation unit 1 and the X-ray imaging unit 10. The drive time (image accumulation time) of the two-dimensional X-ray image capturing unit 11 is set.

On the other hand, if it is determined in step S2 that there is no synchronization signal, the detection delay and end time due to the automatic X-ray detection may be misunderstood, and the process proceeds to step S4. In step S4, after calculating the image accumulation time T at the time of shooting, the process proceeds to step S5, and after changing the drive timing based on the image accumulation time T at the time of shooting obtained in step S4, the process proceeds to step S3. In the present embodiment, the drive method setting unit 23 sets the drive timing so that the charge accumulation start time is increased by taking the delay time (Δt ^k : FIG. 3) into account, and the charge accumulation start time is increased. To change.

In step S3, when the time variation of the Vs signal is monitored and the X-ray is irradiated, the X-ray is detected when there is no synchronization signal, and imaging is started at the determined drive timing. When the time change of the Vs signal is larger than a predetermined reference, Δt ^k can be predicted to be short. Conversely, when the time change of the Vs signal is equal to or less than the reference, Δt ^k is predicted to be long. That is, time change of Vs signal can be used to predict Delta] t ^k. When the time variation is small Delta] t ^k of the Vs signal is long Thus, the shorter fixed accumulation time. This not only reduces image noise due to wasted accumulation time, but also allows images to be transferred quickly. Although the sequence will be described later, when preparation is completed, the X-ray imaging unit 10 outputs a preparation end signal to the X-ray generation unit 1. When the X-ray generation unit 1 receives an X-ray irradiation button (not shown) after receiving the preparation end signal, the X-ray generation unit 1 outputs the X-ray generation signal to the X-ray imaging unit 10. The X-ray generator 1 generates X-rays after the X-ray imaging unit 10 receives the X-ray generation signal. After receiving the X-ray generation signal, the two-dimensional X-ray imaging unit 11 of the X-ray imaging unit 10 reads out the charges accumulated in the image accumulation time T at the drive timing described above, and forms an image from the read charges. .

  When the imaging in step S3 is completed, the process proceeds to step S6. When there is a connection synchronization signal, the image is transferred to the X-ray generation unit 1 after the image accumulation time T has elapsed, and the imaging is completed.

  In step S <b> 7, it is determined whether or not the drive timing has been changed for the captured image. If the drive timing has not been changed, the process proceeds to step S8, and the preprocessing unit 16 performs, for example, default preprocessing for an accumulation time of 500 ms. Next, in step S9, after the image processing unit 17 performs default image processing, in step S10, under the control of the CPU 19, an image processed image is processed in advance using a film or film designated by the operator on the operation panel 21. The image is output to an output medium such as the image display unit 22.

  On the other hand, if it is determined in step S7 that the drive timing is changed, the process proceeds to step S11, and the preprocessing unit 16 performs preprocessing corresponding to the image accumulation time T based on the changed drive timing. The preprocessing executed in step S11 differs from the default preprocessing in dark current correction. This is because the amount of accumulated dark current changes when the image accumulation time T is changed by changing the drive timing. The dark current image has a characteristic that depends on the image accumulation time T. Therefore, in order to improve the image quality, it is desirable to perform correction with a dark current image having an image accumulation time T equal to the changed image accumulation time. Therefore, the influence of the changed image accumulation time T on the image quality is reduced by correcting the dark current amount according to the changed image accumulation time T.

  In the two-dimensional X-ray image capturing unit 11 using a photoelectric conversion element, there are mainly two timings for acquiring a dark current image. One is to capture (acquire) a dark current image immediately after acquisition of an X-ray image. The other is to set a predetermined time in advance within the image accumulation time T, and to acquire a dark current image at several image accumulation times T. The method of acquiring a dark current image at the former timing requires only an extra time until the image is displayed in still image shooting. In this case, for example, in moving image shooting, acquiring a dark current image after an X-ray image has an adverse effect that extra time is required for acquiring a plurality of images. On the other hand, the method of acquiring the dark current image at the latter timing needs to store a plurality of dark current images corresponding to the corresponding image accumulation time in advance. In this case, since it is not necessary to acquire a dark current image after acquiring an X-ray image, there is an advantage that the time required to display an image can be shortened.

  In this embodiment, any dark current image acquisition method can be used. The preprocessing unit 16 performs a dark current correction process by taking a difference (a subtraction process) of the dark current image corresponding to the corresponding image accumulation time T from the X-ray image. After performing the dark current correction processing, the preprocessing unit 16 performs gain correction processing and outputs an image in which the characteristics of each photoelectric conversion characteristic are corrected.

  After completion of the preprocessing in step S11, the process proceeds to step S12. The image processing executed in step S12 differs from, for example, default image processing in noise reduction processing (noise suppression processing) corresponding to the image accumulation time T. For example, if the drive timing is changed to increase the image accumulation time T in order to avoid unnecessary X-ray irradiation, noise increases in the image. In the present embodiment, noise reduction processing including frequency processing is included, and when the drive timing is changed and the image accumulation time T becomes longer, frequency processing with a stronger enhancement coefficient in the specific frequency image of noise reduction processing is performed. Do.

  When the image processing in step S12 is completed, the process proceeds to step S10. In step S10, the image processed image is controlled in advance by the CPU 19 under the control of the CPU 19, such as a film, an image display unit 22, or the like designated by the operator on the operation panel 21. To the output medium. FIG. 5 is an explanatory diagram of an operation sequence between the X-ray generation unit and the X-ray imaging unit of the conventional X-ray imaging apparatus, and FIG. 6 is an X-ray generation unit in the X-ray imaging apparatus according to the present embodiment. 2 is an explanatory diagram of a sequence of 1 and the X-ray imaging unit 10. The operation sequence in the X-ray imaging apparatus of this embodiment will be specifically described by comparing FIG. 5 and FIG.

  First, FIG. 5 in the conventional example shows an operation sequence when the image accumulation time T is set to 1000 ms. In the operation sequence of FIG. 5, the operator places the subject P between the X-ray generation unit and the X-ray imaging unit, and notifies the subject or patient of the start of imaging, and then the first stage of the X-ray generation unit. Turn on the switch (SW). The X-ray generation unit transmits an RDY_REQ signal to the X-ray imaging unit, and the X-ray imaging unit finishes reading the previous image and starts preparation for imaging. It should be noted that a sensor that requires idle reading or the like performs idle reading driving.

  Then, the X-ray imaging unit transmits an RDY_OK signal to the X-ray generation unit after a delay of, for example, 100 ms, and permission to turn on the second-stage switch (SW) is obtained in the X-ray generation unit. Next, the operator turns on the second-stage switch (SW) of the X-ray generation unit, transmits an X_REQ signal to the X-ray imaging unit, and sets up the generator. When receiving the X_REQ signal, the X-ray imaging unit initializes the two-dimensional X-ray imaging unit 11 that is a sensor unit. Then, after a delay of about 100 ms, the X-ray imaging unit transmits an X_OK signal to the X-ray generation unit 1, and the generator X-ray is released.

  Conventionally, the X-ray generation unit and the X-ray imaging unit are connected by a dedicated line. For example, as shown in FIG. 5, it is sufficient to start image reading after a fixed accumulation time of 1000 ms.

  Next, in the operation sequence (FIG. 6) of the X-ray imaging apparatus according to the present embodiment, the connection state with the X-ray generation unit 1 is grasped on the X-ray imaging unit 10 side. A determination signal (CNN_CHK) for determining a connection state is transmitted from the X-ray imaging unit 10 to the X-ray generation unit 1 and a response signal (CNN_RET) returned from the X-ray generation unit 1 is received. For example, if the OS (operation system) of the X-ray imaging unit 10 is Windows (or MS-DOS), Linux, or the like, a connection result can be obtained by sending a ping (packet internet groper) command. .

  The purpose of this sequence is to confirm the stability of communication in the connected state. As this embodiment, for example, commands such as winipcfg, arp, traceroute, netstat, ipconfig, route, and telnet on Windows (or MS-DOS) may be used. Further, it is desirable to confirm the connection state on an application used for the X-ray imaging unit 10. For example, even information on the IP level, which is a level that can be confirmed by the ping described above, and information on the network layer of the OSI reference model can be applied to the present embodiment.

  When the response signal (CNN_RET) returns normally, that is, when there is a synchronization signal between the X-ray generation unit 1 and the X-ray imaging unit 10, the drive timing is not changed, so that it is the same as the conventional FIG. Operation sequence. However, when the response signal (CNN_RET) does not return normally, that is, when there is no synchronization signal between the X-ray imaging unit and the X-ray imaging apparatus, the operation sequence shown in FIG. 6 is performed.

  In the operation sequence of FIG. 6, when the response signal (CNN_RET) does not return within a certain time, the synchronization signal presence / absence detection unit 28 has no synchronization signal between the X-ray imaging unit 10 and the X-ray generation unit 1. Is detected. As shown in FIG. 6, the following exchange of signals cannot be performed between the X-ray imaging unit 10 and the X-ray generation unit 1. For this reason, the X-ray imaging unit 10 stops the preparation drive of the two-dimensional X-ray imaging unit 11 only when it is detected that X-rays are irradiated using the X-ray automatic detection function, and predetermined fixed accumulation is performed. After time, it is necessary to read out the current or voltage of each pixel. At this time, in the case of an external environment in which synchronous communication is impaired, there is a possibility that image reading is delayed by the amount of X-ray detection time. In addition, there is a possibility that a delay may occur in the time from the X-ray irradiation to the detection.

  In the present embodiment, in consideration of such a communication situation, a table in which the image accumulation time T is set according to the connection method and the imaging region is provided. As described above, the driving method setting unit 23 determines the image accumulation time T in synchronization with the X-ray generation unit 1 when the detected synchronization signal is present. Here, “synchronization” includes both at the start of accumulation and at the end of accumulation, but there is also an X-ray generation unit that has no synchronization signal only at the end of accumulation. For this reason, when there is no synchronization signal only at the end of accumulation, the charge signal of the pixel is read after a predetermined image accumulation time. When the detected synchronization signal is absent, the method is changed to a method of acquiring an image with a longer fixed accumulation time than when the synchronization signal is present (for example, the fixed accumulation time 1000 ms is changed to the accumulation time 950 ms) To do).

  FIG. 7 illustrates a screen of the operation panel 21 of the X-ray imaging unit 10. The operation panel 21 is provided with a patient information display field 31 such as a patient name, an X-ray image display unit 32, and a synchronous connection state display unit 33. In addition, the operation panel 21 can be connected to the connection method only on one side, the synchronous connection switch button 34, the imaging start button 35 for instructing the start of imaging, the message display field 36 for displaying a comment, etc. An imaging region selection unit 37 to be displayed is provided.

  When the X-ray generation unit 1 and the X-ray imaging unit 10 are connected by a dedicated line, the synchronization connection state display unit 33 displays the dedicated line. For the synchronous connection switching button 34, a connection method that can be handled by the X-ray imaging apparatus can be selected by pull-down, for example.

  After the operator selects an imaging region by the imaging region selection unit 37 and displays “X-ray imaging is possible” or the like in the message display field 36, the operator presses the imaging start button 35 to capture an X-ray image. Can be directed.

  When the synchronous connection switching button 34 is pressed, the presence / absence of the synchronous connection is detected. When the asynchronous connection cannot be changed to the synchronous connection, the fact that the synchronous connection cannot be changed is displayed in the message display field 36 of the operation panel 21.

  FIG. 8 is a diagram for exemplarily explaining noise reduction processing in the image processing unit 17, and is an explanatory diagram of discrete wavelet transform and its inverse transform. 8A is a frequency component decomposition circuit diagram, FIG. 8B is a configuration diagram of a two-level conversion coefficient group obtained by two-dimensional conversion processing, and FIG. 8C is a configuration diagram of a restoration circuit. ing. In the noise reduction process, an image is decomposed into a plurality of frequency components, and noise data is generated by analyzing noise superimposed on each frequency component. By subtracting this noise data from each frequency component, noise existing in the corresponding band can be reduced.

  In the present embodiment, even when there is no synchronization signal and there is no synchronization signal, the X-ray irradiation time is kept within the image accumulation time T of the X-ray image capturing apparatus by changing the drive timing to lengthen the image accumulation time. By increasing the image accumulation time T, dark current noise enters the image. These dark current noises are caused by photodiodes corresponding to each pixel, variations in individual differences among amplifiers, and the like, and appear in a state where fixed pattern noise and random noise are mixed. Further, these dark current noises monotonously increase as the image accumulation time T becomes longer. Since this dark current noise is different in frequency from the image representing the X-ray distribution after passing through the subject P, it is possible to improve the image quality by performing frequency decomposition and performing restoration by weighting that weakens the enhancement coefficient of the corresponding frequency component image. It is possible to reduce the influence.

Since the dark current noise also has a fixed pattern according to the image accumulation time T, it has a certain tendency under the image in which the corresponding frequency component is divided into subbands. It is assumed that the spatial frequency in the noise component increased as the image accumulation time T becomes longer corresponds to the frequency subband HH2 in FIG. 8B, for example. In this case, the noise reduction process in this embodiment reduces the component corresponding to the frequency subband HH2 and adds them in the restoration circuit of FIG. The noise reduction processing in the present embodiment can adjust the subtraction amount of noise data in a plurality of stages. By changing the value of the parameter for adjusting the subtraction amount, it becomes possible to reduce the noise in the corresponding band. In this way, by changing the noise reduction processing by the above-described method with respect to the change of the drive timing, dark current noise can be reduced and the image quality can be improved.
(Second Embodiment)
In the first embodiment, the configuration in which the image accumulation time T is changed depending on the presence or absence of the synchronous connection has been described. In the present embodiment, a configuration in which an imaging region is also added as a criterion for changing the image accumulation time T will be described. Moreover, in 2nd Embodiment, the structure which changes the drive method of the two-dimensional X-ray image imaging | photography part 11 in order to acquire a dark current image after X-ray irradiation is demonstrated.

  FIG. 9 is a timing chart of the X-ray imaging by the X-ray imaging apparatus according to the second embodiment of the present invention. In the first embodiment, the driving method (image accumulation time T) of the two-dimensional X-ray image capturing unit 11 of the X-ray image capturing apparatus is changed according to the connection state in communication. In the present embodiment, the driving method setting unit 23 selects a table using not only the connection information indicating the connection state but also the imaging region information. The driving method setting unit 23 changes the image accumulation time T by selecting a table corresponding to the imaging part information indicating the connection state and the imaging part.

  Also in the second embodiment, as in the first embodiment, signals (CNN_CHK, CNN_RET) for determining a connection state are communicated between the X-ray generation unit 1 and the X-ray imaging unit 10 in advance. The synchronization signal presence / absence detection unit 28 transmits a determination signal (CNN_CHK) for determining the connection state between the X-ray generation unit 1 and the X-ray imaging unit 10 to the X-ray generation unit 1. When communication between the X-ray generation unit 1 and the X-ray imaging unit 10 is established, the X-ray generation unit 1 sends a response signal (CNN_RET) to the X-ray imaging unit 10 in response to the determination signal (CNN_CHK). Send. When communication between the X-ray generation unit 1 and the X-ray imaging unit 10 is not established, the X-ray generation unit 1 does not transmit a response signal (CNN_RET) to the X-ray imaging unit 10 side. At this time, since it is not a connection state in which a synchronization signal can be exchanged, a response signal (CNN_RET) for checking the connection state is not returned to the X-ray imaging unit 10 side.

  In the second embodiment, the driving method of the two-dimensional X-ray image capturing unit 11 is further changed in order to acquire a dark current image after X-ray irradiation.

  When the synchronization signal is detected, the acquisition timing of the dark current image acquired after the X-ray irradiation can be grasped on the X-ray imaging unit 10 side, so that the number of acquired dark current images is sufficient. However, when the synchronization signal is not detected, the acquisition timing of the dark current image acquired after the X-ray irradiation cannot be grasped on the X-ray imaging unit 10 side. When the X-ray irradiation time is long, X-rays may be irradiated when the dark current image is acquired. Therefore, the dark current image acquisition method is changed. For example, the acquisition method is changed to acquire, for example, three sheets so as to acquire a plurality of dark current images acquired after X-ray irradiation (901 to 903 in FIG. 9). By changing the method for acquiring the dark current image in this way, the possibility that the X-ray irradiation time falls within the image accumulation time T is increased. As an example of acquiring a plurality of dark current images, acquisition of three dark current images is exemplary, and the gist of the present invention is not limited to this example.

  FIG. 10 is a diagram illustrating a flow of X-ray imaging performed by the X-ray imaging apparatus according to the second embodiment. The same contents as those in the flowchart shown in FIG. 4 are denoted by the same step numbers, and description thereof is omitted. If it is determined in step S2 in FIG. 10 that the synchronization signal is not detected, the process proceeds to step S21. In step S <b> 21, the imaging part input by the operator via the imaging part selection unit 37 of the operation panel 21 is selected. By selecting an imaging region to be imaged at the time of image capturing, the required frequency and gradation are different, and the amount of X-ray irradiation to be irradiated is also different for each imaging region.

  In step S22, it is determined whether or not the imaging region selected in step S21 is a region having a large X-ray irradiation amount (more than the threshold X-ray irradiation amount) (irradiation amount determination). For example, when the lumbar side surface, hip joint, femur, or the like is selected as a site with a large amount of X-ray irradiation (S22-Yes), the process proceeds to step S4, and the image accumulation time T at the time of imaging is changed. When a region near the heart or the like is selected as another region, for example, a region with a small amount of X-ray irradiation (less than the threshold X-ray irradiation amount) (S22-No), generally the X-ray irradiation time is short. . For this reason, even if the synchronization signal is not detected and the immediacy of communication is lacking, the need to change the drive timing of the X-ray imaging unit is reduced, so that the process is performed without changing the drive timing. Proceed to S3.

  In step S22, the method of estimating the X-ray irradiation dose based on the imaging region has been described. However, the gist of the present invention is not limited to this example. For example, the X-ray irradiation time input to the X-ray generation unit 1 may be collected by the data collection unit 15 of the X-ray imaging unit 10 and the X-ray irradiation time may be used for the determination in step S22. The drive method setting unit 23 can also determine whether or not to change the drive timing in step S22 by using the X-ray irradiation time collected by the data collection unit 15.

  If the drive timing is changed according to the determination result of step S7, in step S13, the pre-processing unit 16 has a plurality of dark current images in an asynchronous connection state under a charge accumulation time equal to the changed drive timing. And evaluate (analyze) the dark current image. In step S <b> 14, the preprocessing unit 16 analyzes the dark current image and determines the image, thereby determining whether or not X-rays are emitted during charge accumulation due to dark current (charge accumulation time) (charge). Judgment). The level of charge due to dark current is different from the level of charge due to X-ray irradiation. The preprocessing unit 16 compares the charge levels to determine whether or not X-rays are emitted during charge accumulation due to dark current.

  If there is X-ray irradiation in the determination result in step S14, the process proceeds to step S15, and the preprocessing unit 16 adds the image at the time of charge accumulation due to dark current to the X-ray image, and adds the added image to the X-ray image. An image is formed as a line image (S15). The image added to the X-ray image is deleted from the plurality of acquired dark current images. For example, in the timing chart of FIG. 9, since X-rays are irradiated (X_ON) at the dark current charge accumulation timing 901, an image based on the charges accumulated at the accumulation timing 901 is added to the X-ray image.

  In step S16, the preprocessing unit 16 selects a dark current image (for example, one of the accumulation timings 902 and 903 in FIG. 9) used for dark current correction from the dark current image acquired thereafter.

  In step S17, the preprocessing unit 16 performs dark current correction using the dark current image selected in the previous step S16. Details of the dark current correction are as described in step S11 of FIG. 4 of the first embodiment. After step S17 ends, the process proceeds to image processing in step S12.

  On the other hand, if it is determined in step S14 that X-rays are not irradiated when dark current charges are accumulated, the process proceeds to step S11, and the preprocessing unit 16 performs image accumulation time based on the changed drive timing. Pre-processing corresponding to T is performed. That is, the pre-processing unit 16 performs dark current correction using any one of the plurality of dark current images acquired in step S13. Details of the dark current correction are as described in step S11 of FIG. 4 of the first embodiment. After step S11 ends, the process proceeds to image processing in step S12.

  In step S12, the image processing unit 17 performs image processing (noise reduction processing) according to the changed image accumulation time T. Table 1 illustrates the relationship between the image accumulation time T and the image processing method according to the presence / absence of the synchronization signal and the part.

Table 1
Synchronization presence / absence Part X-ray irradiation time Image accumulation time T Image processing method Asynchronous chest 20 ms 500 ms Image processing 1
Asynchronous thoracic spine side, etc. 350 ms 1000 ms Image processing 2
Synchronous chest 20ms 500ms Image processing 1
Synchronous Thoracic side etc. 350ms 500ms Image processing 1
Table 1 above shows specific examples of numerical values for changing the image processing method in accordance with the image accumulation time T for the purpose of improving the image quality when the image accumulation time T is changed. For example, in imaging including the heart such as the front of the chest, since there are many parts that move in accordance with the heart, depending on the rated maximum output value of the X-ray generation unit 1, an X-ray irradiation time that is generally as short as possible is about 30 to 50 ms. It is often photographed at. In addition, other parts are often imaged under short X-ray irradiation conditions of about 30 to 150 ms in order to avoid the subject's body motion being imaged in a blurred manner.

  However, an X-ray irradiation time is required to be long in an imaging region where the amount of X-ray absorption of the subject P is large or an imaging region that requires a high contrast against noise on the image. For example, in a facility that uses the above-mentioned X-ray imaging irradiation conditions, an X-ray irradiation time of about 500 ms is often used for the lumbar side surface, hip joint, and femur. If the accumulation time is 500 ms, it is possible to make the image accumulation time T fall within the X-ray irradiation time when connected in the presence of a synchronization signal, but the tolerance for communication delay is small.

  On the other hand, when imaging a site where the X-ray irradiation time is short, there is a high possibility that the X-ray irradiation time will fall within the image accumulation time T even if there is no synchronization signal. That is, the image accumulation time T is changed according to the imaging part and the connection method. The imaging part is instructed by the operator via the imaging part selection unit 37 (FIG. 7) before the image is taken.

  In the first and second embodiments of the present invention, it is necessary to correct an image shading amount and dark current noise that increase as the image accumulation time T increases. The image processing method implemented in the first and second embodiments of the present invention is solved by applying shading correction noise reduction processing. In addition, as a method for correcting dark current noise, in the present embodiment, it is possible to solve the problem by creating a dark current correction image in accordance with the time from when an X-ray irradiation image is acquired based on a plurality of dark current images acquired. To do.

  The image processing method in Table 1 changes the image processing method according to the imaging region, the accumulation time, and the presence / absence of a synchronization signal. That is, the image processing method can be determined as a function of the imaging region, the image accumulation time, and the wireless / wired function. When the connection method has a synchronization signal, the driving method and the image processing method of the X-ray imaging apparatus may be the same as the conventional example.

  It also has a table for changing the driving method and image processing method according to the imaging region. As the imaging region, the side of the lumbar side, the hip joint, the femur, and the like are particularly changed because the X-ray irradiation time is long. Although not described in Table 1, the driving method and the image processing method can be changed by separating a child or a pregnant woman from an adult in the part for selecting an imaging region. That is, in the case of a child or a pregnant woman, since unnecessary X-ray irradiation must be avoided, the number of parts for changing the driving method and the image processing method is changed.

  FIG. 11 exemplifies various X-ray imaging systems to which an X-ray imaging apparatus can be attached, and includes a chest imaging apparatus, a bucky standing imaging table, a top-and-bottom lifting type bucky table, and a DU alarm type bucky imaging. It can be attached to a device or the like.

  FIG. 12 is a diagram illustrating an X-ray image capturing operation for displaying an image after X-ray image capturing as an example of X-ray image capturing in the embodiment of the present invention. The flow of operations of the X-ray generation unit 1, the X-ray imaging unit 10, and the image processing unit 17 is illustrated as a time chart.

  In response to an instruction from the image processing unit 17, the X-ray imaging unit 10 sequentially scans and waits for X-ray irradiation (1201). When there is X-ray irradiation from the X-ray generation unit 1, the X-ray imaging unit 10 detects that X-rays have been irradiated, sequentially stops scanning driving, turns off TFTs in all scanning lines, and enters a charge accumulation state. (1202). At this timing, the X-ray imaging unit 10 reads the image signal from the storage unit 18 and the scanning line number at which scanning was stopped from the register of the two-dimensional X-ray imaging unit 11 and transmits the thinned image to the image processing unit 17. (1203). The image processing unit 17 performs signal processing (1204) on the digital value and displays it (1208).

  In the X-ray imaging unit 10, the thinned images are sequentially read (1206, 1209, 1212, 1213), and finally the images that are not thinned are processed and displayed by the image processing unit 17. The image processing unit 17 displays, for example, three levels of images that are not further thinned over time (1208, 1211, and 1215). When the X-ray generation unit 1 and the X-ray imaging unit 10 are asynchronous, by shortening the accumulation time of the X-ray imaging unit 10, it is possible to reduce image noise due to useless accumulation time, and more excellent immediacy. X-ray imaging apparatus.

  FIG. 13 is a diagram illustrating a timing chart for detecting the start of radiation irradiation and acquiring a captured image as an example of X-ray image capturing in the embodiment of the present invention. The reset scanning (TC101, 1301) is repeated in a state where X-rays can be irradiated, and waiting for X-rays to be irradiated from the X-ray generator. When the X-ray is irradiated, the X-ray is detected and a current flows through the bias line. The bias signal determination unit 25 determines that the X-ray is detected when the bias signal exceeds a certain threshold. For example, the bias signal determination unit 25 can determine that the X-ray has been detected when the waveform of the bias current reaches a peak. Immediately after the determination of X-ray detection, the reset scanning is stopped (TC102), and the accumulation operation is started (1302). The X-ray detection lines from L2 to L7 corresponding to the detection delay time detect X-rays that do not exceed a certain threshold value, and therefore the detection results during this period are not accumulated. For this reason, the detection lines L2 to L7 are lines that partially lose X-rays.

The accumulation operation ends and the read operation starts. It performs a read operation to (TC103,1303) in each line at a certain fixed time, wherein by calculating the time variation of the bias signal, it is possible to predict Delta] t ^k. The accumulation time can be set according to the time change of the bias signal. The time change of the bias current appears as a slope when time is taken on the horizontal axis and the bias current is taken on the vertical axis. When the inclination is small, the time variation of the bias current is small, Delta] t ^k becomes longer. Thus switching the fixed accumulation time so short as appropriate time Delta] t ^k.

Also, in order to eliminate unnecessary generation of X-rays as much as possible, the bias signal threshold should be low. However, since the bias signal is a minute current, if the threshold value is lowered, there is little delay after X-ray irradiation and it is possible to transition to the image accumulation operation. Conversely, when there is a change in the bias signal due to vibration or the like, May be misdetected. Therefore, the threshold value can be changed depending on the installation environment. The accumulation time can be set according to the threshold value of the bias signal. Set threshold is when large, the Delta] t ^k is increased by switching a short fixed storage time, in particular it is possible to reduce the image noise due to unnecessary accumulation time, also it becomes faster can transfer images.

According to each of the above-described embodiments, it is possible to set the driving method of the image capturing unit according to the connection state between the X-ray generation unit and the X-ray imaging unit and the sensitivity state of X-ray detection.
(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (15)

An X-ray imaging apparatus having an image imaging means for imaging an X-ray image generated from the X-ray generation means, the X-ray imaging means comprising:
A determination unit that determines whether or not communication is performed between the X-ray generation unit and the X-ray imaging unit to synchronize the timing of X-ray generation and the drive timing of the X-ray imaging unit;
In response to the determination, the image capturing unit is driven so that an accumulation time when the asynchronous communication without the synchronized communication is performed is shorter than an accumulation time when the synchronized communication is performed. A setting means for setting a method;
An X-ray imaging apparatus comprising: The determination means includes
When the determination signal for determining whether or not the communication is performed is transmitted to the X-ray generation unit, and the response signal for the determination signal is received from the X-ray generation unit, the X-ray generation unit And the X-ray imaging means are determined to be in a connection state in which synchronized communication is performed,
The X-ray generation unit and the X-ray imaging unit are determined to be in a connection state in which asynchronous communication is performed when a response signal to the determination signal is not received from the X-ray generation unit. The X-ray imaging apparatus according to 1.   The setting means has a shooting mode with a shorter storage time than the shooting mode of the image shooting means in the connection state in which the synchronized communication is performed as the shooting mode of the image shooting means in the connection state in which the asynchronous communication is performed. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus is set. The image photographing means has a sensor array in which a plurality of conversion elements that convert the X-rays into electric charges are arranged,
The setting means changes the accumulation time by changing at least one of a timing for starting accumulation of the charge in the conversion element and a timing for starting reading of the charge accumulated in the conversion element. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus is set.   When the X-ray generation unit and the X-ray imaging unit are in a connection state in which synchronized communication is performed, the setting unit is configured to perform the driving by communication between the X-ray generation unit and the X-ray imaging unit. The X-ray imaging apparatus according to claim 2, wherein a method is set. The X-ray imaging means includes
An acquisition means for acquiring a plurality of dark current images in a connection state in which the asynchronous communication is performed;
A charge determination unit that compares the charges of the plurality of dark current images with the charges at the time of irradiation with the X-rays and determines whether or not the X-rays are irradiated at the time of accumulation of dark current charges;
6. The apparatus according to claim 2, further comprising processing means for processing an image at the time of accumulation of the dark current charge as an X-ray image when the X-ray is irradiated. The X-ray imaging apparatus described. The X-ray imaging means includes
A selection means for selecting an imaging region of the subject;
A dose determining means for determining a dose of X-rays according to the imaging region;
Further comprising
The said setting means sets the drive method of the said image pick-up means using the determination result and the determination result of the said X-ray irradiation amount, The any one of Claim 2 thru | or 6 characterized by the above-mentioned. An X-ray imaging apparatus described in 1. When the determination result is a connection state in which asynchronous communication is performed, and the determination result of the X-ray dose is equal to or higher than a threshold X-ray dose,
The setting means sets the accumulation time of the image photographing means in the connection state where the asynchronous communication is performed shorter than the accumulation time of the image photographing means in the connection state where the synchronous communication is performed. The X-ray imaging apparatus according to claim 7. The X-ray imaging means includes
9. The method according to claim 2, further comprising preprocessing means for correcting the X-ray image by taking a difference between dark current images from an X-ray image photographed by the driving method of the image photographing means. The X-ray imaging apparatus of Claim 1.   The preprocessing means acquires the X-ray image at the accumulation time of the image photographing means in a connection state in which the asynchronous communication is performed, and a dark current image at an image accumulation time equal to the accumulation time of the image photographing means. The X-ray imaging apparatus according to claim 9, wherein the X-ray image is corrected by taking a difference between the dark current image and the X-ray image. The X-ray imaging means includes
The X-ray image capturing apparatus according to claim 2, further comprising an image processing unit that performs image processing on an X-ray image captured by the driving method of the image capturing unit. .   The image processing means reduces noise included in the X-ray image by frequency processing in which an enhancement coefficient at a specific frequency is increased with respect to an X-ray image captured in a connection state in which asynchronous communication is performed. The X-ray imaging apparatus according to claim 11. An X-ray imaging unit having an image imaging unit for imaging an X-ray image generated from the X-ray generation unit;
Whether the determination unit of the X-ray imaging unit communicates between the X-ray generation unit and the X-ray imaging unit to synchronize the timing of X-ray generation and the drive timing of the X-ray imaging unit A determination step of determining whether or not,
According to the determination, the setting unit of the X-ray imaging unit compares the accumulation time when the asynchronous communication is not performed and the accumulation time when the synchronous communication is performed. A setting step of setting a driving method of the image photographing means so as to be short;
A control method for an X-ray imaging apparatus, comprising: An X-ray imaging apparatus having an image imaging means in which a conversion element for converting X-rays generated from the X-ray generation means into electric charges is disposed, wherein the X-ray imaging means includes:
A determination unit that determines whether or not communication is performed between the X-ray generation unit and the X-ray imaging unit to synchronize the timing of X-ray generation and the drive timing of the X-ray imaging unit;
In accordance with the determination, a driving method of the image photographing unit in which at least one of timing for starting accumulation of electric charge in the conversion element and timing for starting reading of the accumulated electric charge is changed. Setting means for setting;
An X-ray imaging apparatus comprising: A control method for an X-ray imaging apparatus comprising: an X-ray imaging means having an image imaging means in which a conversion element for converting X-rays generated from the X-ray generation means into electric charge is disposed;
Whether the determination unit of the X-ray imaging unit communicates between the X-ray generation unit and the X-ray imaging unit to synchronize the timing of X-ray generation and the drive timing of the X-ray imaging unit A determination step of determining whether or not,
In accordance with the determination, the setting unit of the X-ray imaging unit sets at least one of a timing for starting accumulation of charges in the conversion element and a timing for starting reading of the accumulated charges. A setting step of setting the changed driving method of the image photographing means;
A control method for an X-ray imaging apparatus, comprising:

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