JP2017093646A - X-ray image diagnostic apparatus and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray image diagnostic apparatus and an image processing method capable of improving the efficiency of examination using X-ray images.SOLUTION: An X-ray image diagnostic apparatus includes an X-ray detector, an image generation unit, a calculation unit, and a control unit. The X-ray detector detects X-rays applied from an X-ray tube during a prescribed time, and generates output signals corresponding to the prescribed time as output signals per unit time. The image generation unit generates pieces of first X-ray image data based on the output signals generated per unit time respectively, and generates second X-ray image data corresponding to the prescribed time using the plurality of pieces of first X-ray image data. The calculation unit calculates imaging conditions on the basis of the X-ray image data collected before collecting the plurality of pieces of first X-ray image data. The control unit controls the X-ray detector and the image generation unit on the basis of the calculated imaging conditions.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an X-ray diagnostic imaging 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. In addition, with the advent of X-ray detectors capable of high-speed readout, moving object blurring caused by the movement of an imaging target is obtained by using a plurality of X-ray image data obtained by collecting X-ray incident information in a short time. A technique for generating corrected X-ray image data has been considered. Specifically, a plurality of X-ray image data is collected at an acquisition rate shorter than an output rate (display rate) at which the X-ray detector outputs a display image (X-ray image). One display image in which moving object blur is corrected is generated using a plurality of X-ray image data collected by the line detector.

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

  The problem to be solved by the present invention is to provide an X-ray image diagnostic apparatus and an image processing method capable of improving the efficiency of examination using an X-ray image.

  The X-ray image diagnostic apparatus according to the 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. The image generation unit generates first X-ray image data based on the output signal generated every unit time, and uses the plurality of first X-ray image data to correspond to the second time. X-ray image data is generated. 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 image diagnostic apparatus according to the first embodiment. FIG. 2 is a diagram for explaining a normal mode of imaging by the X-ray image diagnostic apparatus. FIG. 3 is a diagram for explaining a high-speed drive mode of imaging by the X-ray image diagnostic apparatus. FIG. 4A is a diagram for explaining numerical values used for calculation of imaging conditions according to the first embodiment. FIG. 4B is a diagram for explaining numerical values used for calculation of imaging conditions according to the first embodiment. FIG. 4C is a diagram for explaining numerical values used for calculation of imaging 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 processing steps of the X-ray image diagnostic apparatus according to the first embodiment.

  Hereinafter, an X-ray image diagnostic 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 image diagnostic apparatus 1 according to the first embodiment. As shown in FIG. 1, the X-ray image diagnostic 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. A display 15, a display 16, a storage circuit 17, an input circuit 18, and a processing circuit 19.

  The bed 11 is movable in the vertical direction and the horizontal direction, and has a top plate on which the subject P1 is placed. The holding arm 12 holds the X-ray generator 13 and the X-ray detector 14 facing each other. The X-ray generator 13 includes an X-ray diaphragm (also referred to as a collimator) and a quality control filter 13a used for the purpose of reducing the exposure dose to the subject P1 and improving the image quality of the image data, and an X-ray tube that irradiates X-rays. 13b. The X-ray detector 14 detects X-rays irradiated from the X-ray tube 13b and transmitted through the subject P1. The X-ray detector 14 generates an output signal from the detected X-ray and outputs it to the processing circuit 19. The X-ray detector 14 is also referred to as 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 point 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 that is referred to by an operator, and displays shooting conditions in shooting, image data generated by shooting, and the like under the control of the processing circuit 19.

  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. Further, the storage circuit 17 stores each program 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 that are used by the operator to input various instructions and various settings. The processing circuit 19 receives instructions and setting information received from the operator. 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 in FIG. 1, each processing function performed by the component control function 19a, the image generation function 19b, and the calculation function 19c is recorded in the storage circuit 17 in the form of a program executable by a computer. The processing circuit 19 is a processor that realizes a function corresponding to each program by reading the program from the storage circuit 17 and executing the 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 of FIG. In FIG. 1, it has been described that the processing functions performed by the control function 19a, the image generation function 19b, and the calculation function 19c are realized by a single processing circuit, but the processing is performed by combining a plurality of independent processors. A function may be realized by configuring a circuit and causing each processor to execute a program.

  The term “processor” used in the above description is, for example, a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (for example, A circuit such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). The processor implements the function 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 into the processor circuit. In this case, the processor realizes the function by reading and executing the program incorporated in the circuit. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining a plurality of independent circuits to realize the function. Good. Furthermore, a plurality of components in FIG. 1 may be integrated into one processor to realize the function.

  The control function 19a in the first embodiment is an example of a control unit in the claims. The image generation function 19b in 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 image diagnostic apparatus. Specifically, the processing by the X-ray image diagnostic apparatus is used for imaging such as calculation of imaging conditions, X-ray exposure, X-ray detection, output signal generation, X-ray image data generation, and image display. This is a series of processes. Here, the processing circuit 19 controls the drive 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 display signal from the X-ray image data based on the generated output signal. An X-ray image is generated. That is, the processing circuit 19 drives the X-ray detector 14 so as to collect 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”. Further, the X-ray image data for display generated by the processing circuit 19 using the frame is referred to as “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 so as to collect 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 single display image from a plurality of frames by setting the frame collection rate by the X-ray detector 14 to be higher than the display rate of the display image (the X-ray incident information reading speed is increased). You can also Hereinafter, a mode for generating one display image from one frame is referred to as a normal mode. A mode for generating a display image using a plurality of frames is referred to as a high-speed drive mode. Further, the processing circuit 19 calculates imaging conditions using X-ray image data collected in advance, and controls 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 in detail later. Hereinafter, collection of X-ray image data used for calculation of imaging conditions is referred to as pre-collection.

  The overall configuration of the X-ray image diagnostic apparatus according to the first embodiment has been described above. With such a configuration, the X-ray diagnostic imaging apparatus according to the first embodiment increases the examination efficiency by calculating imaging conditions for imaging in the high-speed drive mode based on the previously collected X-ray image data. Improve.

  First, a conventional X-ray image diagnostic apparatus will be described. In a conventional X-ray image diagnostic apparatus, the two imaging modes, the normal mode and the high-speed drive mode described above, can be executed. Hereinafter, these photographing modes will be described with reference to FIGS. FIG. 2 is a diagram for explaining a normal mode of imaging by the X-ray image diagnostic apparatus. FIG. 3 is a diagram for explaining a high-speed drive mode of imaging by the X-ray image diagnostic apparatus. 2 and 3 is a part to be examined, and is a dynamic part such as a heart.

  In imaging in the normal mode, the X-ray diagnostic imaging 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 normal mode, the X-ray diagnostic imaging apparatus has the same frame collection rate and display image display rate, and one frame becomes one display image. Then, as shown in the lower part of FIG. 2, 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. Here, in imaging in the normal mode, moving object blur as shown in the lower part of FIG. 2 may occur due to movement of the target part P2 during “predetermined time: 3T” which is a unit time.

  In radiography in the high-speed drive mode, the X-ray diagnostic imaging apparatus, for example, as shown in the upper part of FIG. 3, generates a plurality of “division times: T” obtained by dividing “predetermined time: 3T” into three unit times. One display image is generated from a plurality of frames based on each output signal. That is, in the case of the high-speed drive mode, one frame is acquired for each collection rate (for example, “division time: T”) shorter than the display rate of the display image (for example, one display image is displayed for each “predetermined time: 3T”). One display image is generated from a plurality of frames (for example, 3 frames) collected in (acquisition). Here, when the X-ray detector 14 is driven at a high speed and a frame is generated every shorter unit time, as shown in the middle part of FIG. 3, the influence of the movement of the target part P2 is small, and moving object blurring hardly occurs. . However, the amount of information included in the frame is reduced by shortening the unit time for generating the output signal. Specifically, the amount of information included in the frame shown in the middle part of FIG. 3 is reduced to about one third of the amount of information included in the frame (display image) shown in the lower part of FIG. Therefore, in the shooting in the high-speed drive mode, as shown in the lower part of FIG. 3, the three frames generated with “division time: T” as a unit time are integrated so as to correct the shift between the frames. Thus, it is possible to generate a display image in which moving object blur is corrected while preventing a reduction 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 division number. That is, the number of divisions is the same as the number of frames used for generating one display image in the high-speed drive 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 drive mode, the X-ray diagnostic imaging apparatus generates a frame for each divided time, and uses the plurality of generated frames to display a display image that has been subjected to moving object blur correction at predetermined time intervals. Generate. On the other hand, in the normal mode, the X-ray diagnostic imaging apparatus generates a display image every predetermined time. Note that, in the high-speed drive mode, a frame generated every divided time may be referred to as first X-ray image data. A display image generated every predetermined time may be described 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 driving 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 the shooting in the high-speed drive mode, the influence of circuit noise increases as the number of divisions (number of frames) increases. In the conventional X-ray diagnostic imaging apparatus, since the high-speed driving mode is applied under uniform conditions, the influence of circuit noise exceeds the gain due to the motion blur correction, and further, the signal to noise of the X-ray image used for the inspection It is assumed that the ratio decreases and the inspection efficiency decreases.

  Therefore, the X-ray image diagnostic apparatus 1 according to the first embodiment controls the processing circuit 19 described in detail below, while setting the signal-to-noise ratio in the display image and the frame within an appropriate range. In addition, the inspection efficiency is improved by generating a display image that has been subjected to motion blur correction in the high-speed drive mode. Specifically, the X-ray image diagnostic apparatus 1 according to the first embodiment calculates the number of divisions (number of frames) as an imaging condition based on pre-collected X-ray image data. Execute shooting. Here, the X-ray image diagnostic apparatus 1 according to the first embodiment can use a fluoroscopic image collected before photographing, a photographed image photographed in the past, or the like as the pre-collected X-ray image data. For example, the X-ray diagnostic imaging apparatus 1 uses, for example, a fluoroscopic image collected before imaging of the subject P1 to determine whether to perform the high-speed driving mode, the number of divisions (number of frames) in the high-speed driving mode, and imaging. The imaging conditions including the X-ray irradiation conditions at the time are calculated. Details of each process will be described below.

  Returning to FIG. 1, the control function 19 a 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 performs control so that shooting is performed based on the shooting condition calculated by the calculation function 19c described later. For example, the control function 19a controls the collection of fluoroscopic images for the target part 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 images for the target part P2.

  The image generation function 19b generates X-ray image data based on the output signal output from the X-ray detector 14 in the 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 electrical / voltage conversion, A (Analog) / D (Digital) conversion, and parallel / serial conversion on the electrical signal received from the X-ray detector 14 to generate a frame. The image generation function 19b generates a display image using the frame.

  Here, in the high-speed drive 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 a plurality of first X-ray images corresponding to the predetermined time. Second X-ray image data based on the X-ray image data is generated every predetermined time. In other words, as described above, the image generation function 19b generates a frame for each divided time when shooting is performed in the high-speed drive mode, and generates a display image using the plurality of generated frames. Here, the image generation function 19b performs image processing on a plurality of frames to generate a display image. For example, the image generation function 19b generates a display image in which moving object blur is corrected using a plurality of frames for each division time. An arbitrary method can be applied to the correction of the moving object blur used here. Further, the correction process executed using a plurality of frames is not limited to the moving body blur correction, and may be a case where other correction processes are executed.

  The calculation function 19c calculates an imaging condition based on pre-collected X-ray image data (for example, a fluoroscopic image) before imaging in the high-speed drive mode. Specifically, the calculation function 19c estimates the signal amount and the noise amount included in the display image that can be generated by imaging in the high-speed drive mode based on the pre-collected X-ray image data, and the estimated signal amount The imaging conditions are calculated based on the noise amount. More specifically, the calculation function 19c estimates the gain rate by the moving body blur correction of the signal amount included in the display image that can be generated by the imaging in the high-speed drive mode based on the pre-collected X-ray image data. The imaging 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, the case of performing moving body blur correction will be described as an example, but the embodiment is not limited to this. For example, the gain factor by other image processing is estimated, and the estimated gain factor is calculated. Based on this, it may be a case where the photographing condition is calculated.

First, the calculation function 19c uses the X-ray image data (for example, a fluoroscopic image) collected in advance and the signal amount “S” and noise of the X-ray image data obtained when imaging is performed in the normal mode. An estimated value 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 that is a noise caused by statistical fluctuations in the number of X-ray photons and the distribution. Accordingly, the calculation function 19c calculates the estimated value of the quantum motor “σ _q ” and 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”. Accordingly, the noise amount σ included in the X-ray image data obtained when 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 an arbitrary 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. It should be noted that the signal-to-noise ratio of the X-ray image data obtained when imaging is performed in the normal mode according to 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 the shooting condition that provides the maximum efficiency in consideration of the improvement and decrease in image quality when shooting is performed in the high-speed drive mode. In other words, the calculation function 19c calculates the optimum shooting condition when performing shooting in the high-speed drive mode in consideration of image quality improvement obtained by image processing such as moving body blur correction and image quality degradation due to circuit noise. . For example, the calculation function 19c according to the first embodiment uses the signal amount “S” and the circuit described above as the estimated values of the signal amount and the noise amount in the X-ray image data obtained when imaging is performed in the high-speed drive mode. Calculation is performed using noise “σ _e ”.

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

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

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

  Here, the gain factor “k” by moving object blur correction included in Expression (4) will be described. The gain factor “k” varies depending on 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 expressed by a function “k (n, s)”, for example. it can. The mobility “s” is an index value indicating how much the target part P2 has moved during a predetermined time when generating the display image. For example, the mobility “s” is the same as the signal amount “S” and the noise amount “σ”. It can be calculated by a known method from pre-collected X-ray image data (for example, a fluoroscopic image).

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

Hereinafter, with reference to FIGS. 4A to 4C, details of numerical values used for calculation of imaging conditions will be described with examples. 4A to 4C are diagrams for explaining numerical values used for calculation of 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, Using the equation (4), the number of divisions (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 the above-described calculation of the shooting conditions are as shown in FIGS. 4A to 4C, for example, depending on the situation. Note that FIG. 4A shows a case where there is no moving body blur in the target part P2 and imaging is performed in the normal mode. FIG. 4B shows a case where there is moving object blur in the target part P2 and imaging is performed in the normal mode. FIG. 4C shows a case where there is moving object blur in the target part P2 and imaging 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. “S” is shown. Moreover, the figure shown to the lower stage of FIG. 4A-FIG. 4C shows the example of the numerical value in each condition.

  First, the mobility “s” will be described. The mobility “s” corresponds to the number of pixels in which the target part P2 is displayed over a predetermined time, and when there is no moving body blur, for example, as shown in FIG. Is the number “1”. On the other hand, when there is moving object blur, for example, as shown in FIG. 4B, if 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 “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 such a case, for example, as shown in FIG. 4B, if the signal amount “3S” is detected by being divided into three pixels by the movement of the target portion P2, the signal amount detected per pixel is “S”. It becomes. Here, for example, when moving body blur correction is performed in the high-speed drive mode as shown in FIG. 4C and information detected by dividing into three pixels is integrated into one pixel, the signal amount per pixel becomes “3S”. . That is, when moving object blur occurs, the signal amount included in the X-ray image data acquired in the high-speed drive mode is “3S” with respect to the signal amount “S” included in the X-ray image data acquired in the normal mode. ”And increases three times. The gain factor “k” is the ratio of the signal amount included in the X-ray image data acquired by performing moving body blur correction in the high-speed drive 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 rate “k” varies depending on the mobility “s” of the subject and the number of divisions (number of frames) “n”. For example, when moving object blur correction is performed in the high-speed driving mode with the number of divisions (number of frames) “n” set to “2” with respect to the moving object blur shown in FIG. 4B, signals that can be included in the corrected X-ray image data The maximum amount is “2S”, and the gain factor “k” is “2”. In addition, as described above, when moving object blur correction in the high-speed drive mode is performed with the number of divisions (number of frames) “n” set to “3” for the moving object blur shown in FIG. 4B, the gain factor “k”. Becomes “3”. 4B, even if the division number “n” is set to “4 or more”, 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 X-ray image data collected in advance, the gain rate “k” is the number of divisions (the number of frames) “ n ”. That is, in Expression (4), the substantial variables are the signal-to-noise ratio “SNR _corr ” and the number of divisions (number of frames) “n”. The calculation function 19 c according to the first embodiment By _obtaining the maximum value of the noise ratio “SNR _corr ”, the number of divisions (number of frames) “n” can be calculated.

The calculation function 19c according to the first embodiment calculates the number of divisions (number of frames) “n” at which the signal-to-noise ratio “SNR _corr ” in Equation (4) becomes the maximum value, and the storage circuit 17 Remember me. The calculation function 19c according to the first embodiment generates an output signal with a predetermined time as a unit time as a shooting condition when the number of divisions (number of frames) “n” is less than “1” as a result of calculation. The normal mode to be set 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 for the target region P2.

  Note that the calculation function 19c according to the first embodiment determines whether or not 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 acquired in advance satisfies the following formula (5). If not, the calculation of the value of the division number (frame number) “n” is not executed.

Here, “SNR _ip ” in Expression (5) is, for example, executed in the high-speed drive mode when the image generation function 19b generates a display image while performing moving body blur correction from a plurality of frames. Therefore, the minimum signal-to-noise ratio required for each frame generated using the division time as a unit time is shown. That is, the calculation function 19c according to the first embodiment is performed when the mobility “s” satisfies the quadratic inequality of the mobility “s” developed from the equation (5) to the following equation (6). The calculation of the value of the number of divisions (number of frames) “n” is executed.

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

Further, the calculation function 19c according to the first embodiment calculates the value of the division number (the number of frames) “n” so that the signal-to-noise ratio “SNR _corr ” becomes the maximum value in the equation (4). Furthermore, the division number (frame number) “n” may be corrected. For example, the calculation result of the number of divisions (number of frames) “n” based on the equation (4) is calculated in a continuous numerical range, but the calculation function 19c determines that the number of divisions (number of frames) “n” is discrete. It is possible to store it in the storage circuit 17 as a photographing condition after performing a process with any one of the numerical values. For example, the calculation function 19c can perform a process of setting the number of divisions (number of frames) “n” calculated as a decimal number as a natural number. Note that the calculation function 19c performs, for example, a round-up process or a round-down process as a process for setting the number of divisions (number of frames) “n” as a discrete numerical value.

  Further, the calculation function 19c according to the first embodiment may further correct the X-ray exposure condition after correcting the value of the division number (the number of frames) “n”. For example, since the signal-to-noise ratio of the X-ray image data acquired from the process changes from the division number (the number of frames) “n” to a discrete numerical value, the calculation function 19c is used for the X-ray exposure condition. Is corrected to change the signal amount “S”, so that the change in the signal-to-noise ratio due to the correction of the number of divisions (number of frames) “n” can be offset.

  Next, an example of a processing procedure 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 processing steps of the X-ray image diagnostic 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. Step 104 and step 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). If the inspection start request is not accepted (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 collection of fluoroscopic images for the subject P1 (Step 102). Then, the processing circuit 19 generates a fluoroscopic image (Step 103).

Next, the processing circuit 19 uses the fluoroscopic image generated in step 103 to capture the signal amount “S”, the quantum motor “σ _q ”, the circuit noise “σ _e ”, the mobility when shooting in the normal mode. “S” is estimated (step 104), and the imaging condition is calculated so that the signal-to-noise ratio “SNR _corr ” is maximized (step 105). Then, the processing circuit 19 controls the execution of shooting based on the shooting conditions calculated in step 105 (step 106), and generates a frame for each unit time (step 107). Here, when photographing is 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, when the shooting is performed in the high-speed drive mode (Yes at Step 108), the processing circuit 19 uses the plurality of frames generated with the divided time as the unit time in Step 107, and the display image is subjected to moving body blur correction. (Step 109), the display image generated in step 109 is output to the storage circuit 17, and the process ends.

  Note that the processing circuit 19 may control the calculated shooting conditions to be displayed on the display 16 and present them to the operator when the shooting conditions are calculated in step 105. Further, the processing circuit 19 may start shooting on the condition that a shooting start request is received from the operator via the input circuit 18 in step 106.

  In addition, the processing circuit 19 may use a photographed image taken immediately before the start of the examination or a photographed picture taken in the past, instead of the fluoroscopic images pre-collected 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 X-ray image data as long as the signal amount “S”, noise “σ”, and mobility “s” in the 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 per unit time. It generates with each output signal. The image generation function 19b generates first X-ray image data based on the output signal generated every unit time, and uses the plurality of first X-ray image data to generate a second X-ray corresponding to a predetermined time. Line image data is generated. The calculation function 19c calculates imaging conditions 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 noise amount included in the second X-ray image data that can be generated by imaging in the imaging mode based on the pre-collected X-ray image data. An imaging 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 a signal-to-noise ratio of 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 deterioration in image quality due to an increase in circuit noise can be generated, and inspection efficiency can be improved.

  In addition, according to the first embodiment, the image generation function 19b performs image processing on the plurality of first X-ray image data to generate the second X-ray image data. The calculation function 19c further estimates a gain rate by image processing of the 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 pre-collected X-ray image data. The imaging condition is calculated based on the estimated gain factor. That is, the calculation function 19c estimates the gain factor, which is the effect of moving object blur correction in the high-speed driving mode, based on the mobility “s” acquired from the pre-collected X-ray image data, and obtains the gain factor “k”. Set the shooting conditions based on this. Therefore, the X-ray image diagnostic apparatus according to the first embodiment sets the imaging conditions in consideration of the effect of the moving body blur correction in the high-speed drive mode for each examination, and sets the X-ray image data appropriately subjected to the moving body blur correction. Can be generated and the inspection efficiency can be improved.

  Further, according to the first embodiment, the calculation function 19c calculates the number of divisions (the number of frames) when dividing a predetermined time into division times as shooting conditions. 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 that can obtain the maximum efficiency.

  Further, according to the first embodiment, the calculation function 19c calculates the imaging condition on the condition that the movement of the target part in a predetermined time is below a predetermined threshold. In other words, when the mobility “s” does not satisfy the predetermined condition and it is difficult to perform moving body 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 image diagnostic apparatus according to the first embodiment can reduce unnecessary calculation time and improve inspection efficiency.

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

(Second Embodiment)
In the first embodiment, the case where the division number (the number of frames) is calculated as the imaging condition so that the signal-to-noise ratio of the X-ray image data generated by imaging is maximized has been described. In the second embodiment, the number of divisions (number of frames) is calculated so that the signal-to-noise ratio of the X-ray image data generated by imaging becomes a predetermined setting value set in advance 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 that of the X-ray image diagnostic apparatus 1 according to the first embodiment shown in FIG. 1, and a part of the processing by the calculation function 19c is performed. Is different. Therefore, the same reference numerals as those in FIG. 1 are given to the components having the same configurations as those described in the first embodiment, and the description thereof is omitted.

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

Here, “SNR _Req ” in Expression (7) and Expression (8) is a predetermined value that is set in advance. For example, a signal pair that is set for each inspection and is required at the minimum for an image used for each inspection. Indicates the noise ratio. Note that the greater the number of divisions (number of frames) “n”, the faster the X-ray detector 14 is driven, and an output signal is generated every shorter unit time. As a result, the gain factor “k”, which is the effect of the motion blur correction, is increased.

  As described above, according to the second embodiment, the calculation function 19c calculates the number of divisions (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 in which the signal-to-noise ratio has a predetermined setting value, and can improve examination efficiency.

  Here, in the X-ray image diagnostic apparatus 1 according to the second embodiment, the calculation function 19c is configured so that the number of divisions (the number of frames) “in the 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 that maximizes the effect of the moving body blur correction in the high-speed drive mode, thereby improving the inspection efficiency.

  In the X-ray diagnostic imaging apparatus 1 according to the second embodiment, the minimum signal-to-noise ratio required in the inspection is maintained while maximizing the effect of moving object blur correction in the high-speed drive mode. 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 (number of frames) is calculated as the imaging condition has been described. On the other hand, in the third embodiment, a case where an X-ray exposure condition is calculated as an imaging condition will be described.

  The X-ray image diagnostic apparatus 1 according to the third embodiment has the same configuration as that of the X-ray image diagnostic apparatus 1 according to the first embodiment shown in FIG. 1, and a part of the processing by the calculation function 19c is performed. Is different. Therefore, the same reference numerals as those in FIG. 1 are given to the components having the same configurations as those described in the first embodiment, and the description thereof is omitted.

The calculation function 19c according to the third embodiment calculates the X-ray exposure condition 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 a signal amount “S” that satisfies the following expression (9), and an X-ray exposure condition corresponding to the calculated signal amount “S”. Are stored in the storage circuit 17 as imaging conditions. Note that “SNR _Req ” in Equation (9) is a predetermined set value that is preset by an operator or the like.

  Note that the calculation function 19c according to the third embodiment presets the division number (number of frames) “n” prior to the calculation of the X-ray exposure conditions. For example, the calculation function 19c sets the number of divisions (the number of frames) “n” required for appropriately performing moving body blur correction based on the movement amount “s” estimated from the pre-collected X-ray image data. To do. Further, for example, the calculation function 19 c receives a setting of the number of divisions (number of frames) “n” from the operator via the input circuit 18.

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

  As described above, according to the third embodiment, the calculation function 19c calculates the X-ray exposure condition 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 inspection efficiency. Can do.

  In addition, according to the third embodiment, the calculation function 19c performs the motion blur correction in the high-speed drive mode with the predetermined number of divisions (number of frames) “n”, and then 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 necessary level. Therefore, the X-ray diagnostic imaging apparatus according to the third embodiment can reduce the exposure dose of the subject.

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

  In the first and second embodiments described above, a case has been described in which the number of divisions (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. . However, the embodiment is not limited to this, and for example, after calculating “n”, the imaging condition may be set again. For example, the X-ray irradiation condition may be reset after calculating “n”.

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

  Here, the calculation function 19c preferentially adjusts “mAs (tube current × irradiation time)” in order to refrain from the influence of the image quality, so that the signal amount “S ′” that satisfies the equation (10) is satisfied. Is calculated. Further, the calculation function 19c may calculate an X-ray condition that minimizes the exposure dose among the signal amount “S ′” that satisfies the equation (10).

  Each component of each device according to the first to fourth embodiments is functionally conceptual 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 one shown in the figure, and all or a part of the distribution / integration may be functionally or physically distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or a part of each processing function performed in each device may be realized by a CPU and a program that is analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  The control methods described in the first to fourth embodiments can be realized by executing a control program prepared in advance 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 can also be executed by being 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 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 presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other 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 the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 X-ray-image diagnostic apparatus 19 Processing circuit 19a Control function 19b Image generation function 19c Calculation function

Claims (13)

An X-ray detector that detects X-rays exposed from an 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;
First X-ray image data is generated based on the output signal generated every unit time, and second X-ray image data corresponding to the predetermined time using a plurality of the first X-ray image data. An image generation unit for generating
A calculation unit that calculates imaging conditions based on X-ray image data collected before collecting the first X-ray image data;
A control unit for controlling 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 the 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 signal amount and the 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 calculation unit is further configured to gain a signal amount included in the second X-ray image data based on the X-ray image data collected before the first X-ray image data is generated by the image processing. The X-ray image diagnostic apparatus according to claim 2, wherein a rate is estimated, and the imaging condition is calculated based on the estimated gain rate.   The X-ray image diagnostic apparatus according to claim 1, wherein the calculation unit calculates the number of unit times within the predetermined time as the imaging condition.   The X-ray image diagnosis apparatus according to claim 4, wherein the calculation unit calculates the number of the unit times in which the signal-to-noise ratio of the second X-ray image data is a maximum value.   The X-ray image diagnosis apparatus according to claim 4, wherein the calculation unit calculates the number of unit times at which a signal-to-noise ratio of the second X-ray image data is a predetermined set value.   The X-ray diagnostic imaging apparatus according to any one of claims 4 to 6, wherein the calculation unit calculates the imaging conditions on condition that the movement of the target part in the predetermined time is below a predetermined threshold.   The X-ray image diagnostic apparatus according to claim 4, wherein the calculation unit further corrects the X-ray exposure condition after calculating the number of unit times.   The X-ray image diagnosis apparatus according to claim 1, wherein the calculation unit calculates an X-ray exposure condition as the imaging condition.   The X-ray diagnostic imaging apparatus according to claim 9, wherein the calculation unit calculates the exposure condition in which a signal-to-noise ratio of the second X-ray image data is a predetermined setting value.   The X-ray image diagnosis apparatus according to claim 9, wherein the calculation unit calculates a tube current value of the X-ray tube as the exposure condition.   The X-ray image diagnosis apparatus according to claim 1, 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 exposed from an X-ray tube for a predetermined time and generating an output signal corresponding to the predetermined time as an output signal for each unit time;
First X-ray image data is generated based on the output signal generated every unit time, and second X-ray image data corresponding to the predetermined time using a plurality of the first X-ray image data. An image generation step for generating
A calculation step of calculating imaging conditions based on X-ray image data collected before collecting the first X-ray image data;
A control step for controlling the X-ray detection step and the image generation step based on the calculated imaging conditions;
An image processing method including:

Images