JP6651332B2 - X-ray image diagnostic apparatus and image processing method - Google Patents

Description

  Embodiments of the present invention relate to an X-ray image diagnostic apparatus and an image processing method.

  In recent years, the reading speed of X-ray incident information by an X-ray detector has been increased. Also, with the advent of an X-ray detector capable of high-speed readout, the use of a plurality of X-ray image data obtained in a short period of time to collect X-ray incident information reduces moving object blur caused by movement of an imaging target. Techniques for generating corrected X-ray image data have been considered. Specifically, the X-ray detector collects a plurality of pieces of X-ray image data at an acquisition rate shorter than an output rate (display rate) at which a display image (X-ray image) is output. Using the plurality of X-ray image data collected by the line detector, one display image in which moving object blur and the like are corrected is generated.

JP 2011-139903 A JP 2014-117368 A JP 2011-224331 A JP 2010-201103 A

  An object of the present invention is to provide an X-ray image diagnostic apparatus and an image processing method that can improve the efficiency of an examination using an X-ray image.

An X-ray image diagnostic apparatus according to an embodiment includes an X-ray detector, an image generation unit, a calculation unit, and a control unit. The X-ray detector detects X-rays emitted from the X-ray tube for a predetermined time, and generates an output signal corresponding to the predetermined time as an output signal for each unit time. Image generator is based on the generated output signal for each unit time, it forms a plurality of first X-ray image data corresponding to a plurality of said unit time continuous raw plurality of the first The second X-ray image data corresponding to the predetermined time is generated using the X-ray image data. The calculation unit calculates an imaging condition based on the X-ray image data collected before collecting the first X-ray image data. The control unit controls the X-ray detector and the image generation unit based on the calculated imaging conditions.

FIG. 1 is a block diagram illustrating a configuration example of the X-ray diagnostic imaging apparatus according to the first embodiment. FIG. 2 is a diagram for explaining a normal mode of imaging by the X-ray diagnostic imaging apparatus. FIG. 3 is a diagram for explaining a high-speed driving mode of imaging by the X-ray diagnostic imaging apparatus. FIG. 4A is a diagram for explaining numerical values used for calculating the imaging conditions according to the first embodiment. FIG. 4B is a diagram for explaining numerical values used for calculating the imaging conditions according to the first embodiment. FIG. 4C is a diagram for explaining numerical values used for calculating the photographing conditions according to the first embodiment. FIG. 5 is a graph for explaining the mobility condition according to the first embodiment. FIG. 6 is a flowchart for explaining a series of flows of processing of the X-ray diagnostic imaging apparatus according to the first embodiment.

  Hereinafter, an X-ray diagnostic imaging apparatus according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration example of an X-ray diagnostic imaging apparatus 1 according to the first embodiment. As shown in FIG. 1, the X-ray diagnostic imaging apparatus 1 according to the first embodiment includes a bed 11, a holding arm 12, an X-ray generator 13, an X-ray detector 14, and an X-ray high voltage generator. It comprises a device 15, a display 16, a storage circuit 17, an input circuit 18, and a processing circuit 19.

  The couch 11 is movable in the vertical and horizontal directions, and has a top plate on which the subject P1 is placed. The holding arm 12 opposes and holds the X-ray generation unit 13 and the X-ray detector 14. The X-ray generation unit 13 includes an X-ray aperture (also referred to as a collimator) and a quality control filter 13a used for reducing the exposure dose to the subject P1 and improving the image quality of image data, and an X-ray tube for irradiating X-rays. 13b. The X-ray detector 14 detects X-rays emitted from the X-ray tube 13b and transmitted through the subject P1. Further, the X-ray detector 14 generates an output signal from the detected X-ray and outputs it to the processing circuit 19. Note that the X-ray detector 14 is also called an FPD (Flat Panel Detector). Further, the X-ray detector 14 according to the first embodiment can generate an output signal for each unit time from the detected X-ray. This will be described in detail later.

  The X-ray high voltage generator 15 supplies a high voltage to the X-ray tube 13b. The display 16 is a monitor referred to by an operator, and displays, under the control of the processing circuit 19, shooting conditions in shooting, image data generated by shooting, and the like.

  The storage circuit 17 stores data used when the processing circuit 19 controls the entire processing by the X-ray image diagnostic apparatus 1, X-ray image data, and the like. The storage circuit 17 stores programs executed by the processing circuit 19.

  The input circuit 18 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, and the like used by the operator for inputting various instructions and various settings. The input circuit 18 sends information of instructions and settings received from the operator to the processing circuit 19. Forward. For example, the input circuit 18 receives a test start request from the operator.

  The processing circuit 19 executes a control function 19a, an image generation function 19b, and a calculation function 19c. In the embodiment shown in FIG. 1, the processing functions performed by the component control function 19a, image generation function 19b, and calculation function 19c are recorded in the storage circuit 17 in the form of a program executable by a computer. The processing circuit 19 is a processor that reads out a program from the storage circuit 17 and executes the program to realize a function corresponding to each program. In other words, the processing circuit 19 in a state where each program is read has each function shown in the processing circuit 19 in FIG. In FIG. 1, the processing function performed by the control function 19a, the image generation function 19b, and the calculation function 19c is described as being realized by a single processing circuit, but the processing is performed by combining a plurality of independent processors. A circuit may be configured, and each processor may execute a program to realize a function.

  The term “processor” used in the above description may be, for example, a CPU (central processing unit), a GPU (graphics processing unit), or an application specific integrated circuit (ASIC), a programmable logic device (eg, It refers to circuits such as simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs). The processor realizes functions by reading and executing the program stored in the storage circuit 17. Instead of storing the program in the storage circuit 17, the program may be directly incorporated in the circuit of the processor. In this case, the processor realizes a function by reading and executing a program incorporated in the circuit. Note that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, but may be configured as one processor by combining a plurality of independent circuits to realize its function. Good. Further, a plurality of components in FIG. 1 may be integrated into one processor to realize its function.

  The control function 19a in the first embodiment is an example of a control unit in the claims. The image generation function 19b according to the first embodiment is an example of an image generation unit in the claims. The calculation function 19c in the first embodiment is an example of a calculation unit in the claims.

  The processing circuit 19 controls the entire processing by the X-ray diagnostic imaging apparatus. The processing performed by the X-ray image diagnostic apparatus includes, specifically, calculation of imaging conditions, X-ray exposure, X-ray detection, generation of an output signal, generation of X-ray image data, image display, and the like. This is a series of such processes. Here, the processing circuit 19 controls the driving of the X-ray detector 14 so as to generate an output signal for each unit time from the detected X-ray, and displays the X-ray image data for display from the X-ray image data based on the generated output signal. Generate an X-ray image. That is, the processing circuit 19 drives the X-ray detector 14 so as to acquire X-ray image data for generating an X-ray image for display at a predetermined acquisition rate. Further, the processing circuit 19 generates X-ray image data for display using the X-ray image data collected at a predetermined collection rate. Hereinafter, the X-ray image data based on the output signal output by the X-ray detector 14 is referred to as a “frame”. The display X-ray image data generated by the processing circuit 19 using the frame is referred to as a “display image”.

  Here, the processing circuit 19 can generate a display image using an arbitrary number of frames. For example, the processing circuit 19 can control the X-ray detector 14 to acquire frames at the same acquisition rate as the display rate of the display image, and generate one display image from one frame. That is, the processing circuit 19 can directly use the frame based on the output signal of the X-ray detector 14 as a display image. Further, the processing circuit 19 generates a display image from a plurality of frames by increasing the frame collection rate of the X-ray detector 14 to be higher than the display rate of the display image (by increasing the reading speed of the X-ray incident information). You can also. Hereinafter, a mode in which one display image is generated from one frame is referred to as a normal mode. A mode in which a display image is generated using a plurality of frames is referred to as a high-speed driving mode. Further, the processing circuit 19 calculates the imaging conditions using the X-ray image data collected in advance, and controls the imaging based on the calculated imaging conditions. The calculation of the shooting conditions and the shooting based on the calculated shooting conditions will be described later in detail. Hereinafter, acquisition of X-ray image data used for calculating the imaging conditions is referred to as pre-acquisition.

  The overall configuration of the X-ray diagnostic imaging apparatus according to the first embodiment has been described. With such a configuration, the X-ray image diagnostic apparatus according to the first embodiment calculates inspection conditions for imaging in the high-speed drive mode based on X-ray image data collected in advance, thereby improving examination efficiency. Improve.

  First, a conventional X-ray image diagnostic apparatus will be described. In the conventional X-ray diagnostic imaging apparatus, the two imaging modes of the normal mode and the high-speed driving mode described above can be executed. Hereinafter, these shooting modes will be described with reference to FIGS. FIG. 2 is a diagram for explaining a normal mode of imaging by the X-ray diagnostic imaging apparatus. FIG. 3 is a diagram for explaining a high-speed driving mode of imaging by the X-ray diagnostic imaging apparatus. The target site P2 in FIGS. 2 and 3 is a site to be inspected, and is a dynamic site such as a heart.

  In the imaging in the normal mode, the X-ray image diagnostic apparatus generates a display image for each output signal (frame) generated with “predetermined time: 3T” as a unit time, for example, as shown in FIG. That is, in the case of the normal mode, the X-ray diagnostic imaging apparatus has the same frame collection rate and display image display rate, and one frame is one display image. Then, the X-ray image diagnostic apparatus displays a display image generated for each output signal, for example, on the display 16 as a diagnostic image, as shown in the lower part of FIG. Here, in shooting in the normal mode, for example, a moving object blur as shown in the lower part of FIG. 2 may occur due to the movement of the target portion P2 during the “predetermined time: 3T” which is a unit time.

  In imaging in the high-speed drive mode, the X-ray image diagnostic apparatus generates a plurality of “divided times: T” obtained by dividing “predetermined time: 3T” into three as a unit time, as shown in the upper part of FIG. One display image is generated from a plurality of frames based on each of the output signals. That is, in the case of the high-speed driving mode, one frame is collected for each collection rate (for example, “divided time: T”) shorter than the display rate of the display image (for example, one display image is displayed for every “predetermined time: 3T”). One display image is generated from a plurality of frames (for example, three frames) collected in (collection). Here, when the X-ray detector 14 is driven at a high speed to generate a frame for each shorter unit time, as shown in the middle part of FIG. 3, the influence of the movement of the target portion P2 is small, and the moving object blur is less likely to occur. . However, by reducing the unit time for generating the output signal, the amount of information included in the frame decreases. Specifically, the information amount included in the frame shown in the middle part of FIG. 3 is reduced to about one third of the information amount contained in the frame (display image) shown in the lower part of FIG. Therefore, in shooting in the high-speed driving mode, as shown in the lower part of FIG. 3, it is necessary to integrate three frames generated using the “division time: T” as a unit time so as to correct the mutual frame shift. Accordingly, it is possible to generate a display image in which the moving object blur has been corrected while preventing a decrease in the amount of information. Hereinafter, in the high-speed drive mode, the number of division times included in the predetermined time is referred to as the number of divisions. That is, the number of divisions is the same as the number of frames used to generate one display image in the high-speed driving mode, and means the number of unit times within a predetermined time. For example, the number of divisions in FIG.

  As described above, in the high-speed driving mode, the X-ray diagnostic imaging apparatus generates a frame for each division time, and uses the generated frames to display a display image subjected to moving object blur correction at a predetermined time interval. Generate. On the other hand, in the normal mode, the X-ray diagnostic imaging apparatus generates a display image every predetermined time. In the high-speed drive mode, a frame generated for each division time may be referred to as first X-ray image data. Further, a display image generated every predetermined time may be referred to as second X-ray image data.

  Here, the amount of noise (circuit noise) generated in the data processing increases so as to be substantially proportional to the number of output signals. For example, the circuit noise included in the display image in the high-speed drive mode shown in the lower part of FIG. 3 is about three times the circuit noise included in the display image in the normal mode shown in the lower part of FIG. Further, in shooting in the high-speed driving mode, the influence of circuit noise increases as the number of divisions (number of frames) increases. In the conventional X-ray diagnostic imaging apparatus, the high-speed drive mode is applied under uniform conditions, so that the influence of circuit noise exceeds the gain due to moving object blur correction, and furthermore, the signal-to-noise ratio of the X-ray image used for inspection It is assumed that the ratio decreases and the inspection efficiency decreases.

  Therefore, the X-ray diagnostic imaging apparatus 1 according to the first embodiment controls the processing circuit 19 described in detail below to set the signal-to-noise ratio in the display image or frame to an appropriate range. In addition, the inspection efficiency is improved by generating a display image on which moving object blur correction has been performed in the high-speed drive mode. Specifically, the X-ray image diagnostic apparatus 1 according to the first embodiment calculates the number of divisions (the number of frames) as an imaging condition based on the X-ray image data collected in advance, and calculates the number of divisions based on the calculated number of divisions. Perform the shooting. Here, the X-ray image diagnostic apparatus 1 according to the first embodiment can use, as the X-ray image data collected in advance, a fluoroscopic image collected before imaging, a captured image captured in the past, and the like. For example, the X-ray image diagnostic apparatus 1 uses the fluoroscopic image collected before the imaging of the subject P1 to determine, for example, whether to perform the high-speed driving mode, the number of divisions (the number of frames) in the high-speed driving mode, An imaging condition including an X-ray irradiation condition at the time is calculated. Hereinafter, details of each process will be described.

  Returning to FIG. 1, the control function 19a executes various controls by the processing circuit 19 described above. That is, the control function 19a controls the entire processing by the X-ray image diagnostic apparatus 1. Here, the control function 19a controls to execute shooting based on shooting conditions calculated by a calculation function 19c described later. For example, the control function 19a controls acquisition of a fluoroscopic image for the target site P2. Further, for example, the control function 19a controls the X-ray detector 14 and the image generation function 19b based on the imaging conditions calculated by the calculation function 19c, and controls the collection of the captured image for the target part P2.

  The image generation function 19b generates X-ray image data based on an output signal output from the X-ray detector 14 in fluoroscopy and imaging performed under the control of the control function 19a. Specifically, the image generation function 19b generates a frame based on the output signal output from the X-ray detector 14, or generates a display image using the frame. That is, the image generation function 19b performs an electric-voltage conversion, an A (Analog) / D (Digital) conversion, and a parallel-serial conversion on the electric signal received from the X-ray detector 14 to generate a frame. The image generation function 19b generates a display image using a frame.

  Here, in the high-speed driving mode, the image generation function 19b generates first X-ray image data based on the output signal generated for each division time for each division time, and generates a plurality of first X-ray image data corresponding to a predetermined time. The second X-ray image data based on the X-ray image data is generated at predetermined time intervals. That is, as described above, when shooting is performed in the high-speed drive mode, the image generation function 19b generates a frame for each division time and generates a display image using the generated frames. Here, the image generation function 19b generates a display image by performing image processing on a plurality of frames. For example, the image generation function 19b generates a display image in which moving object blur has been corrected using a plurality of frames for each division time. Note that any method can be applied to the correction of the moving object blur used here. Further, the correction process performed using a plurality of frames is not limited to only the moving object blur correction, and may be a case where another correction process is performed.

  The calculation function 19c calculates imaging conditions based on X-ray image data (for example, a fluoroscopic image) acquired in advance before imaging in the high-speed driving mode. Specifically, the calculation function 19c estimates the signal amount and the noise amount included in the display image that can be generated by the imaging in the high-speed driving mode based on the X-ray image data collected in advance, and calculates the estimated signal amount. And a photographing condition based on the noise amount. More specifically, the calculation function 19c estimates a gain rate by a moving object blur correction of a signal amount included in a display image that can be generated by imaging in the high-speed driving mode, based on the X-ray image data collected in advance. The photographing condition is calculated based on the estimated gain factor. Hereinafter, an example of processing by the calculation function 19c will be described. In the following, a case in which moving object blur correction is performed will be described as an example.However, the embodiment is not limited to this.For example, a gain rate due to other image processing is estimated, and the estimated gain rate is calculated. Based on this, a case where the photographing condition is calculated may be used.

First, the calculation function 19c uses the X-ray image data (for example, a fluoroscopic image or the like) collected in advance to perform the imaging in the normal mode, thereby obtaining the signal amount “S” and the noise of the X-ray image data obtained when the imaging is performed. An estimate of the quantity “σ” is calculated. Here, the noise in the X-ray image data includes the above-described circuit noise and a quantum motor, which is noise caused by statistical fluctuation of the number and distribution of photons of X-rays. Therefore, the calculation function 19c calculates the estimated value of the quantum mottle “σ _q ” and the estimated value of the circuit noise “σ _e ” in order to calculate the estimated value of the noise amount “σ”. Here, the quantum motor “σ _q ” is the square root of the signal amount “S”. Therefore, the noise amount σ included in the X-ray image data obtained when the imaging is performed in the normal mode can be obtained by the following equation (1).

Here, the calculation of the estimated values of the signal amount “S”, the quantum motor “σ _q ”, and the circuit noise “σ _e ” can be performed by applying any method. Hereinafter, in the processing by the calculation function 19c according to the first embodiment, the signal amount “S”, the quantum motor “σ _q ”, and the circuit noise “σ _e ” are treated as constants. The signal-to-noise ratio of the X-ray image data obtained when the imaging is performed in the normal mode by the following equation (2) using the signal amount “S” and the noise amount “σ” calculated as described above. “SNR _normal ” can be calculated.

Here, the calculation function 19c according to the first embodiment calculates an imaging condition that maximizes the efficiency in consideration of an improvement and a decrease in image quality when imaging is performed in the high-speed drive mode. That is, the calculation function 19c calculates an optimum shooting condition when shooting in the high-speed drive mode in consideration of an image quality improvement obtained by image processing such as moving object blur correction and a decrease in image quality due to circuit noise. . For example, the calculation function 19c according to the first embodiment converts the estimated value of the signal amount and the noise amount in the X-ray image data obtained when the imaging is performed in the high-speed driving mode into the signal amount “S” described above and a circuit. It is calculated using the noise “σ _e ”.

  As an example, the calculation function 19c calculates the signal amount of the X-ray image data obtained when the imaging is performed in the high-speed driving mode by “k × S”, and calculates the noise amount “σ” by the following equation (3). ).

Here, “k” included in the signal amount and the noise amount described above indicates a gain rate by moving object blur correction. That is, “k” indicates an image quality improvement rate obtained when moving object blur correction is performed. “N” in Expression (3) indicates the number of divisions (the number of frames). That is, the influence of circuit noise due to the high-speed driving mode increases according to the number of divisions (the number of frames) as shown in Expression (3). As described above, the calculation function 19c calculates the noise amount “σ” to be included in the X-ray image data obtained when the imaging is performed in the high-speed drive mode, by dividing the number (the number of frames) “n” with the moving object blur. It is calculated by the equation (3) using the gain factor “k” by the correction, and the signal amount is calculated by “k × S”. Therefore, the signal-to-noise ratio “SNR _corr ” of the X-ray image data obtained when the imaging is performed in the high-speed driving mode can be calculated by the following equation (4).

The calculation function 19c uses the equation (4) in consideration of the gain factor “k” of the moving object blur correction and the number of divisions (the number of frames) “n”, so that the maximum efficiency can be obtained when shooting in the high-speed drive mode. The obtained photographing conditions are calculated. For example, the calculation function 19c according to the first embodiment uses Expression (4) to calculate the number of divisions at which the signal-to-noise ratio “SNR _corr ” of the X-ray image data obtained when imaging is performed has the maximum value. (Number of frames) “n” is calculated.

  Here, the gain factor “k” by the moving object blur correction included in Expression (4) will be described. The gain factor “k” changes according to the mobility “s”, which is a component of moving object blur, and the number of frames “n” used for moving object blur correction, and can be represented by, for example, a function “k (n, s)”. it can. Note that the mobility “s” is an index value indicating how much the target portion P2 has moved during a predetermined time when a display image is generated, and is, for example, similar to the signal amount “S” and the noise amount “σ”. , Can be calculated from known X-ray image data (for example, a fluoroscopic image) by a known method.

That is, the calculation function 19c estimates the signal amount “S”, the noise amount “σ”, and the mobility “s” using the X-ray image data collected in advance, and calculates the estimated value and the equation (4). ) Is used to calculate the number of divisions n at which the signal-to-noise ratio “SNR _corr ” has the maximum value. The gain factor “k (n, s)” may be calculated by a model solution, or may be calculated under various conditions in advance, and a corresponding value may be extracted from the stored back data and substituted. It may be.

Hereinafter, the details of the numerical values used for calculating the imaging conditions will be described with reference to FIGS. 4A to 4C. FIGS. 4A to 4C are diagrams for explaining numerical values used for calculating the imaging conditions according to the first embodiment. As described above, the calculation function 19c calculates the signal amount “S”, the circuit noise “σ _e ”, and the mobility “s” of the target portion P2 from the X-ray image data collected in advance, and calculates the calculated value and Using equation (4), the number of divisions (the number of frames) “n” at which the signal-to-noise ratio “SNR _corr ” becomes the maximum value is calculated. Here, the numerical values used for calculating the above-described shooting conditions are, for example, as shown in FIGS. 4A to 4C according to the situation. FIG. 4A shows a case in which the moving image is not blurred at the target portion P2 and shooting is performed in the normal mode. FIG. 4B shows a case where a moving object is blurred in the target portion P2 and shooting is performed in the normal mode. FIG. 4C shows a case where a moving object is blurred in the target portion P2 and shooting is performed in the high-speed drive mode. 4A to 4C show the relationship between the pixel (pixel) and the signal amount “S” in each situation, the horizontal axis shows the pixel in the X-ray image data, and the vertical axis shows the signal amount. Indicates "S". 4A to 4C show examples of numerical values in each situation.

  First, the mobility “s” will be described. The mobility “s” corresponds to the number of pixels in which the target portion P2 is displayed over a predetermined time, and when there is no moving object blur, for example, as shown in FIG. Is “1”. On the other hand, when there is a moving object blur, for example, as shown in FIG. 4B, when a signal indicating the same part in the target part P2 is detected over three pixels within a predetermined time due to the movement of the subject, the mobility becomes high. “S” becomes “3”.

  Next, the gain factor “k” will be described. For example, as shown in FIG. 4A, the signal amount when there is no moving object blur is “3S”. In this case, for example, as shown in FIG. 4B, if the signal amount “3S” is detected as being divided into three pixels due to the movement of the target portion P2, the signal amount detected per pixel is “S”. Becomes Here, for example, when the moving object blur correction is performed in the high-speed driving mode as shown in FIG. 4C and the information detected by being divided into three pixels is integrated into one pixel, the signal amount per pixel becomes “3S”. . That is, when the moving object blur occurs, the signal amount “S” included in the X-ray image data acquired in the normal mode and the signal amount included in the X-ray image data acquired in the high-speed driving mode are “3S”. And increases threefold. The gain factor “k” is a ratio of the signal amount included in the X-ray image data acquired by performing the moving object blur correction in the high-speed driving mode to the signal amount included in the X-ray image data acquired in the normal mode. In FIG. 4C, the gain factor “k” is “3”.

As described above, the gain factor “k” varies depending on the mobility “s” of the subject and the number of divisions (the number of frames) “n”. For example, when the moving object blur correction in the high-speed drive mode is performed on the moving object blur illustrated in FIG. 4B by setting the number of divisions (the number of frames) “n” to “2”, a signal that can be included in the corrected X-ray image data The amount is "2S" at the maximum, and the gain factor "k" is "2". Further, as described above, when the moving object blur illustrated in FIG. 4B is subjected to the moving object blur correction in the high-speed drive mode by setting the number of divisions (the number of frames) “n” to “3”, the gain factor “k” Becomes “3”. Note that, even if the number of divisions “n” is set to “4 or more” for the moving object blur shown in FIG. 4B, the gain factor “k” does not become “3 or more”. In the X-ray image diagnostic apparatus according to the first embodiment, since the mobility “s” is a constant determined by the X-ray image data collected in advance, the gain rate “k” is the number of divisions (the number of frames) “ n ". That is, in equation (4), the substantial variables are the signal-to-noise ratio “SNR _corr ” and the number of divisions (the number of frames) “n”, and the calculation function 19c according to the first embodiment performs By _obtaining the maximum value of the noise ratio “SNR _corr ”, the number of divisions (the number of frames) “n” can be calculated.

The calculation function 19c according to the first embodiment calculates the number of divisions (the number of frames) “n” at which the signal-to-noise ratio “SNR _corr ” in Expression (4) becomes the maximum value, and sets the storage circuit 17 as the imaging condition. To memorize. The calculation function 19c according to the first embodiment generates an output signal using a predetermined time as a unit time as a shooting condition when the number of divisions (the number of frames) “n” falls below “1” as a result of the calculation. The normal mode is set and stored in the storage circuit 17. Further, the control function 19a according to the first embodiment controls the X-ray detector 14 and the image generation function 19b based on the imaging conditions calculated by the calculation function 19c, and executes imaging of the target part P2.

  Note that the calculation function 19c according to the first embodiment determines whether the mobility “s” satisfies a predetermined condition before calculating the value of the number of divisions (the number of frames) “n”. It may be a thing. Specifically, the calculation function 19c according to the first embodiment determines whether or not the mobility “s” estimated from the X-ray image data obtained in advance collection satisfies the following expression (5), and satisfies the following equation. If not, the calculation of the value of the number of divisions (the number of frames) “n” is not executed.

Here, “SNR _ip ” in the equation (5) is, for example, when the image generating function 19b performs the moving object blur correction from a plurality of frames while performing the moving object blur correction in the high-speed driving mode. In order to achieve this, the minimum signal-to-noise ratio required for each frame generated with the division time as a unit time is shown. In other words, the calculation function 19c according to the first embodiment performs the case where the mobility “s” satisfies the quadratic inequality of the mobility “s” developed from the equation (5) as in the following equation (6). , The number of divisions (the number of frames) “n” is calculated.

Here, the equation (6) can be shown as a graph in FIG. 5, and the calculation function 19c is, for example, provided that the mobility “s” satisfies “0 ≦ s ≦ s0” in the graph in FIG. , The number of divisions (the number of frames) “n” is calculated. FIG. 5 is a graph for explaining the mobility condition according to the first embodiment. The calculating function 19c performs the above-described determination processing of the signal-to-noise ratio “SNR _ip ” of the frame according to the above-described equation (5) or (6), and when the condition is not satisfied, the moving object in the high-speed driving mode. Since it is difficult to perform the blur correction, the normal mode is set without calculating the value of the number of divisions (the number of frames) “n”.

Further, the calculation function 19c according to the first embodiment calculates the value of the number of divisions (the number of frames) “n” so that the signal-to-noise ratio “SNR _corr ” becomes the maximum value in Expression (4), Further, the number of divisions (the number of frames) “n” may be corrected. For example, the calculation result of the number of divisions (the number of frames) “n” based on Equation (4) is calculated in a continuous numerical range, but the calculation function 19c calculates the number of divisions (the number of frames) “n” discretely. After performing a process of any one of the numerical values, it can be stored in the storage circuit 17 as the photographing condition. As an example, the calculation function 19c can perform a process of setting the number of divisions (the number of frames) “n” calculated as a decimal to a natural number. The calculation function 19c performs, for example, a round-up process or a round-down process as a process of setting the number of divisions (the number of frames) “n” to a discrete numerical value.

  In addition, the calculation function 19c according to the first embodiment may correct the value of the number of divisions (the number of frames) “n”, and then further correct the X-ray exposure condition. For example, since the signal-to-noise ratio of the X-ray image data to be acquired is changed by the process of setting the number of divisions (the number of frames) “n” to a discrete numerical value, the calculation function 19 c To change the signal amount “S”, the change in the signal-to-noise ratio due to the correction of the number of divisions (the number of frames) “n” can be offset.

  Next, an example of a procedure of a process performed by the X-ray image diagnostic apparatus will be described with reference to FIG. FIG. 6 is a flowchart for explaining a series of flows of processing of the X-ray diagnostic imaging apparatus according to the first embodiment. Step 101, step 102, and step 106 are steps corresponding to the control function 19a. Step 103, step 107, step 108, and step 109 are steps corresponding to the image generation function 19b. Steps 104 and 105 are steps corresponding to the calculation function 19c.

  After setting the subject P1 on the bed, the processing circuit 19 determines whether an examination start request has been received from the operator (step 101). Here, when the inspection start request is not received (No at Step 101), the processing circuit 19 enters a standby state. On the other hand, when the examination start request is received (Yes at Step 101), the processing circuit 19 controls the X-ray image diagnostic apparatus to control the acquisition of the fluoroscopic image for the subject P1 (Step 102). Then, the processing circuit 19 generates a perspective image (Step 103).

Next, the processing circuit 19 uses the perspective image generated in step 103 to perform signal capturing in the normal mode, the signal amount “S”, the quantum motor “σ _q ”, the circuit noise “σ _e ”, and the mobility. "S" is estimated (step 104), and photographing conditions are calculated so that the signal-to-noise ratio "SNR _corr " is maximized (step 105). Then, the processing circuit 19 controls execution of photographing based on the photographing conditions calculated in step 105 (step 106), and generates a frame for each unit time (step 107). Here, when the photographing is being performed in the normal mode (No at Step 108), the processing circuit 19 outputs the frame generated at Step 107 to the storage circuit 17, and ends the processing. On the other hand, if the photographing is being performed in the high-speed drive mode (Yes at Step 108), the processing circuit 19 performs the moving image blur correction using the plurality of frames generated at Step 107 with the division time as a unit time. Is generated (step 109), the display image generated in step 109 is output to the storage circuit 17, and the process ends.

  When calculating the photographing condition in step 105, the processing circuit 19 may control the computed photographing condition to be displayed on the display 16 and present it to the operator. Further, the processing circuit 19 may start photographing on condition that a photographing start request has been received from the operator via the input circuit 18 in step 106.

  Further, the processing circuit 19 may use a photographed image photographed immediately before the start of the examination or a photographed image photographed in the past, instead of the fluoroscopic image acquired in advance in steps 102 and 103, X-ray image data collected in advance from a subject different from the subject P1 may be used. That is, the processing circuit 19 may use any type of X-ray image data as long as the signal amount “S”, the noise “σ”, and the mobility “s” in imaging can be estimated.

  As described above, according to the first embodiment, the X-ray detector 14 detects X-rays emitted from the X-ray tube 13b for a predetermined time and outputs an output signal corresponding to the predetermined time for a unit time. It is generated by the output signal of each. The image generation function 19b generates first X-ray image data based on the output signal generated for each unit time, and uses the plurality of first X-ray image data to generate a second X-ray image corresponding to a predetermined time. Generate line image data. The calculation function 19c calculates an imaging condition based on the X-ray image data collected before collecting the first X-ray image data. The control function 19a controls the X-ray detector 14 and the image generation function 19b based on the calculated imaging conditions. Here, the calculation function 19c estimates and estimates the signal amount and the noise amount included in the second X-ray image data that can be generated by imaging in the imaging mode based on the X-ray image data collected in advance. The photographing condition is calculated based on the signal amount and the noise amount. Therefore, the X-ray image diagnostic apparatus 1 according to the first embodiment calculates the signal-to-noise ratio of the X-ray image data obtained by imaging in consideration of circuit noise, and executes imaging under the calculated imaging conditions. X-ray image data that avoids a decrease in image quality due to an increase in circuit noise can be generated, and inspection efficiency can be improved.

  Further, according to the first embodiment, the image generating function 19b performs image processing on the plurality of first X-ray image data to generate the second X-ray image data. The calculating function 19c further estimates a gain rate by image processing of a signal amount included in the second X-ray image data that can be generated by imaging in the high-speed drive mode, based on the X-ray image data collected in advance. The photographing condition is calculated based on the estimated gain factor. That is, the calculation function 19c estimates the gain rate, which is the effect of moving object blur correction in the high-speed drive mode, based on the mobility “s” acquired from the previously collected X-ray image data, and calculates the gain rate “k”. The photographing conditions are set based on the conditions. Therefore, the X-ray image diagnostic apparatus according to the first embodiment sets imaging conditions in consideration of the effect of moving object blur correction in the high-speed driving mode for each examination, and converts the X-ray image data on which the moving object blur correction has been appropriately performed. It can generate and improve inspection efficiency.

  Further, according to the first embodiment, the calculation function 19c calculates the number of divisions (the number of frames) when dividing a predetermined time period into a division time period as an imaging condition. Further, the calculation function 19c calculates the number of divisions at which the signal-to-noise ratio of the second image data becomes the maximum value. Therefore, the X-ray diagnostic imaging apparatus according to the first embodiment can execute the high-speed drive mode in which the maximum efficiency can be obtained.

  Further, according to the first embodiment, the calculation function 19c calculates the imaging condition on the condition that the movement of the target part during a predetermined time is below a predetermined threshold. That is, when the mobility “s” does not satisfy the predetermined condition and it is difficult to perform the moving object blur correction, the calculation function 19c does not calculate the shooting condition in the high-speed drive mode and performs shooting in the normal mode. Execute Therefore, the X-ray diagnostic imaging apparatus according to the first embodiment can reduce unnecessary calculation time and improve examination efficiency.

  In addition, the X-ray image diagnostic apparatus according to the first embodiment sets the X-ray irradiation condition even when the division number (the number of frames) “n” calculated as a decimal is performed as a natural number. Correction can generate X-ray image data having an appropriate signal-to-noise ratio, thereby improving inspection efficiency.

(Second embodiment)
In the first embodiment, a case has been described in which the number of divisions (the number of frames) is calculated as an imaging condition so that the signal-to-noise ratio of X-ray image data generated by imaging is maximized. In the second embodiment, the case where the number of divisions (the number of frames) is calculated such that the signal-to-noise ratio of X-ray image data generated by imaging becomes a predetermined value preset by an operator or the like Will be described.

  The X-ray image diagnostic apparatus 1 according to the second embodiment has the same configuration as the X-ray image diagnostic apparatus 1 according to the first embodiment shown in FIG. Different. Therefore, points having the same configuration as the configuration described in the first embodiment are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.

  The calculation function 19c according to the second embodiment calculates the number of divisions (the number of frames) “n” such that the signal-to-noise ratio of the X-ray image data generated by imaging becomes a predetermined set value. For example, the calculation function 19c calculates the maximum value of the number of divisions (the number of frames) “n” in a range satisfying the following equation (7), and stores the maximum value in the storage circuit 17 as the imaging condition. That is, the calculation function 19c calculates the number of divisions (the number of frames) “n” that indicates the maximum value in the equation (8) obtained by expanding the equation (7).

Here, “SNR _Req ” in Expressions (7) and (8) is a predetermined value that is set in advance, for example, is set for each inspection, and a signal pair minimum required in an image used for each inspection is set. Shows the noise ratio. The larger the number of divisions (the number of frames) “n”, the faster the X-ray detector 14 is driven, and an output signal is generated for each shorter unit time. As a result, the gain factor “k”, which is the effect of moving object blur correction, increases.

  As described above, according to the second embodiment, the calculation function 19c calculates the number of divisions (the number of frames) at which the signal-to-noise ratio of the second X-ray image data becomes a predetermined set value. Therefore, the X-ray image diagnostic apparatus 1 according to the second embodiment can generate and display a display image having a signal-to-noise ratio that is a predetermined set value, and can improve inspection efficiency.

  Here, in the X-ray image diagnostic apparatus 1 according to the second embodiment, the calculation function 19c determines the number of divisions (the number of frames) “in a range where the signal-to-noise ratio of the X-ray image data exceeds a predetermined set value. By calculating the maximum value of “n”, it is possible to generate and display a display image in which the effect of the moving object blur correction in the high-speed drive mode is maximized, thereby improving the inspection efficiency.

  Further, in the X-ray diagnostic imaging apparatus 1 according to the second embodiment, while maximizing the effect of the moving object blur correction in the high-speed drive mode, the X-ray diagnostic apparatus maintains the minimum signal-to-noise ratio required for the inspection. Line image data can be generated, and inspection efficiency can be improved.

(Third embodiment)
In the first and second embodiments, the case where the number of divisions (the number of frames) is calculated as the imaging condition has been described. On the other hand, in the third embodiment, a case will be described in which an X-ray irradiation condition is calculated as an imaging condition.

  The X-ray image diagnostic apparatus 1 according to the third embodiment has the same configuration as the X-ray image diagnostic apparatus 1 according to the first embodiment shown in FIG. Different. Therefore, points having the same configuration as the configuration described in the first embodiment are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.

The calculation function 19c according to the third embodiment calculates the X-ray irradiation conditions so that the signal-to-noise ratio of the X-ray image data generated by imaging becomes a predetermined set value. Specifically, the calculation function 19c according to the third embodiment calculates the signal amount “S” that satisfies the following equation (9), and sets the X-ray irradiation condition corresponding to the calculated signal amount “S”. Is stored in the storage circuit 17 as a photographing condition. Note that “SNR _Req ” in Expression (9) is a predetermined setting value set in advance by an operator or the like.

  Note that the calculation function 19c according to the third embodiment presets the number of divisions (the number of frames) “n” before calculating the X-ray irradiation conditions. For example, the calculation function 19c sets the number of divisions (the number of frames) “n” required to appropriately perform moving object blur correction based on the movement amount “s” estimated from the X-ray image data collected in advance. I do. Further, for example, the calculation function 19c accepts the setting of the number of divisions (the number of frames) “n” from the operator via the input circuit 18.

  The calculation function 19c can calculate, for example, a tube current value and a tube voltage value of the X-ray tube 13b as the X-ray irradiation conditions corresponding to the signal amount “S” calculated from Expression (9). Here, the calculation function 19c can avoid unnecessary influence on the image quality of the captured X-ray image data by setting the tube current value of the X-ray tube 13b as the X-ray irradiation condition. .

  As described above, according to the third embodiment, the calculation function 19c calculates the X-ray irradiation conditions so that the signal-to-noise ratio of the display image becomes a predetermined set value. Here, the calculation function 19c can generate and display a display image that satisfies the signal-to-noise ratio required by the operator by setting the X-ray exposure conditions, thereby improving the inspection efficiency. Can be.

  Further, according to the third embodiment, the calculation function 19c performs the moving object blur correction in the high-speed driving mode with the predetermined number of divisions (the number of frames) “n”, and then performs the required signal-to-noise ratio. Can be generated and displayed, and the inspection efficiency can be improved.

  Further, according to the third embodiment, the calculation function 19c calculates the minimum X-ray exposure condition so that the signal-to-noise ratio of the generated display image satisfies a required level. Therefore, the X-ray diagnostic imaging apparatus according to the third embodiment can reduce the amount of exposure of the subject.

(Fourth embodiment)
The first to third embodiments have been described above, but may be implemented in various different modes other than the above-described first to third embodiments.

  In the first and second embodiments described above, the case where the number of divisions (the number of frames) “n” satisfying each condition in the high-speed drive mode is calculated as the shooting condition and shooting is performed under the calculated shooting condition has been described. . However, the embodiment is not limited to this, and, for example, a case in which “n” is calculated and the shooting conditions are set again may be used. For example, a case where X-ray irradiation conditions are reset after calculating “n” may be adopted.

  As described above, the number of divisions (the number of frames) “n” calculated by the above-described processing is a real number. However, since the actual number of divisions (the number of frames) “n” is an integer, the calculated value is rounded up or down. Therefore, the calculation function 19c can reset the X-ray irradiation condition using the value of “n” after the round-up processing or the round-down processing. For example, the calculation function 19c calculates the signal amount “S ′” that satisfies the following equation (10) using the value of “n” after the round-up processing or the round-down processing.

  Here, the calculation function 19c preferentially adjusts “mAs (tube current × irradiation time)” in order to reduce the influence of the image quality, and thereby the signal amount “S ′” that satisfies the equation (10). Is calculated. Furthermore, the calculation function 19c may calculate the X-ray condition that minimizes the exposure amount among the signal amounts “S ′” that satisfy the equation (10).

  Each component of each device according to the first to fourth embodiments is a functional concept and does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution / integration of each device is not limited to the illustrated one, and all or a part thereof may be functionally or physically distributed / arranged in an arbitrary unit according to various loads and usage conditions. Can be integrated and configured. Furthermore, all or any part of each processing function performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware by wired logic.

  Further, the control methods described in the first to fourth embodiments can be realized by executing a prepared control program on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. The control program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD, and can be executed by being read from the recording medium by the computer.

  According to at least one embodiment described above, inspection efficiency can be improved.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

1 X-ray diagnostic imaging apparatus 19 Processing circuit 19a Control function 19b Image generation function 19c Calculation function

Claims (13)

An X-ray detector that detects X-rays emitted from the X-ray tube for a predetermined time and generates an output signal corresponding to the predetermined time as an output signal per unit time;
And based on the generated output signal for each unit time, it forms a continuous plurality of first X-ray image data corresponding to a plurality of said unit time raw plurality of the first X-ray image data An image generating unit that generates second X-ray image data corresponding to the predetermined time using
A calculating unit configured to calculate an imaging condition based on the X-ray image data collected before collecting the first X-ray image data;
A control unit that controls the X-ray detector and the image generation unit based on the calculated imaging conditions;
An X-ray diagnostic imaging apparatus comprising:   The calculation unit estimates a signal amount and a noise amount included in the second X-ray image data based on X-ray image data collected before generating the first X-ray image data, and estimates The X-ray diagnostic imaging apparatus according to claim 1, wherein the imaging condition is calculated based on the obtained signal amount and noise amount. The image generation unit performs image processing on a plurality of the first X-ray image data to generate the second X-ray image data,
The calculating unit may further include a gain of the signal amount included in the second X-ray image data based on the X-ray image data collected before generating the first X-ray image data. The X-ray diagnostic imaging apparatus according to claim 2, wherein a rate is estimated, and the imaging condition is calculated based on the estimated gain rate.   4. The X-ray image diagnostic apparatus according to claim 1, wherein the calculation unit calculates the number of the unit times within the predetermined time as the imaging condition. 5.   The X-ray image diagnostic apparatus according to claim 4, wherein the calculation unit calculates the number of the unit times at which the signal-to-noise ratio of the second X-ray image data has a maximum value.   The X-ray image diagnostic apparatus according to claim 4, wherein the calculation unit calculates the number of the unit times at which a signal-to-noise ratio of the second X-ray image data becomes a predetermined set value.   The X-ray image diagnostic apparatus according to any one of claims 4 to 6, wherein the calculation unit calculates the imaging condition under a condition that a movement of the target part during the predetermined time is lower than a predetermined threshold.   The X-ray image diagnostic apparatus according to any one of claims 4 to 7, wherein the calculating unit further corrects the X-ray exposure condition after calculating the number of unit times.   The X-ray image diagnostic apparatus according to any one of claims 1 to 3, wherein the calculation unit calculates the X-ray exposure condition as the imaging condition.   The X-ray image diagnostic apparatus according to claim 9, wherein the calculation unit calculates the irradiation condition at which a signal-to-noise ratio of the second X-ray image data has a predetermined set value.   The X-ray image diagnostic apparatus according to claim 9, wherein the calculation unit calculates a tube current value of the X-ray tube as the irradiation condition.   The X-ray image diagnostic apparatus according to any one of claims 1 to 11, further comprising a display control unit that causes the display unit to display the imaging condition calculated by the calculation unit. An X-ray detection step of detecting X-rays emitted from the X-ray tube for a predetermined time and generating an output signal corresponding to the predetermined time as an output signal per unit time;
And based on the generated output signal for each unit time, it forms a continuous plurality of first X-ray image data corresponding to a plurality of said unit time raw plurality of the first X-ray image data An image generating step of generating second X-ray image data corresponding to the predetermined time using
A calculating step of calculating imaging conditions based on X-ray image data collected before collecting the first X-ray image data;
A control step of controlling the X-ray detection step and the image generation step based on the calculated imaging conditions;
An image processing method including:

Images