WO2011074471A1

WO2011074471A1 - X-ray image diagnostic device, x-ray exposure control method and program

Info

Publication number: WO2011074471A1
Application number: PCT/JP2010/072116
Authority: WO
Inventors: 宗作重村; 克己鈴木
Original assignee: 株式会社日立メディコ
Priority date: 2009-12-18
Filing date: 2010-12-09
Publication date: 2011-06-23
Also published as: JPWO2011074471A1

Abstract

Provided are an X-ray image diagnostic device, an X-ray exposure control method, and a program, wherein an appropriate radioscopic X-ray output condition is obtained even when a subject moves during radioscopy. The X-ray image diagnostic device is provided with an X-ray generation means (1) for generating X-rays, an X-ray detection means (2) for detecting transmitted X-rays transmitted through the subject and outputting image data indicating the X-ray intensity of the transmitted X-rays, a region-of-interest setting means (7) for setting a plurality of regions of interest on an X-ray intensity distribution image based on the image data, an X-ray intensity calculation means (8) for calculating the representative values of indexes indicating the X-ray intensities of the respective regions of interest, an X-ray intensity selection means (9) for selecting one representative value from among the representative values of the X-ray intensities of the plurality of regions of interest, and an X-ray exposure control means (5) for performing exposure control of the X-ray generation means (1) on the basis of the selected representative value of the X-ray intensity.

Description

X-ray diagnostic imaging apparatus, X-ray exposure control method and program

The present invention relates to an X-ray diagnostic imaging apparatus, an X-ray exposure control method, and a program, and more particularly to exposure control in an X-ray generation means.

An X-ray diagnostic imaging apparatus that uses an image intensifier (hereinafter abbreviated as “I.I .: Image Intensifier”) as an X-ray detector and has a fluoroscopic function transmits X-rays transmitted through a subject to an I.D. I. , And the detected X-rays are converted into visible light, and the image is converted into a video signal by the camera and camera control unit, output to a monitor such as a CRT, and displayed as a fluoroscopic image. In general, I. As an automatic brightness adjustment function for fluoroscopic images using I. The X-ray control device controls the tube voltage and / or the tube current so that the light amount level in a specific lighting field is compared with the reference level and the light amount level becomes equal to the reference level.

も Even when an X-ray flat detector (hereinafter abbreviated as FPD: Flat Panel Detector) is used as an X-ray detector. Similar to I., the X-ray intensity in the specific ROI (RegionFPOf Interest) in the FPD is compared with the reference X-ray intensity, and the X-ray intensity in the ROI is equal to the reference X-ray intensity. As described above, the X-ray control device controls the tube voltage and / or the tube current.

In the case of the above technology, since the ROI is preset on the assumption that the subject is located at the position assumed in advance, the X-ray irradiated to the subject when the subject deviates from the assumed position Is insufficient or excessive, and there is a problem that it is difficult to display a fluoroscopic image having appropriate luminance. To deal with this problem, for example, Patent Document 1 provides a function for arbitrarily moving an X-ray intensity measurement region (in the above, a lighting field in the case of II and ROI in the case of FPD) on the user side, An X-ray fluoroscopic apparatus capable of obtaining appropriate irradiation X-ray intensity according to a subject is disclosed.

JP 2008-125610 A

However, the technique disclosed in Patent Document 1 has the following problems. That is, in the case of an X-ray examination in which the subject is stationary, the technique disclosed in the above-mentioned Patent Document 1 can sufficiently cope with the X-ray examination in which the subject moves, for example, the esophagus In the case of contrast imaging of the stomach and the appropriate sampling field or ROI, the position of the sampling field or ROI is fixed at the position initially set for the X-ray detector even though the lighting field or ROI always changes. Therefore, the X-ray intensity measurement area is constantly changed on the user side (corresponding to the lighting field in the case of II and ROI in the case of FPD) as the position of the appropriate lighting field or ROI changes. This may reduce inspection efficiency.

The present invention has been made in view of the above circumstances, and an X-ray diagnostic imaging apparatus, an X-ray exposure control method, and a program capable of obtaining an X-ray intensity corresponding to the part regardless of which part is observed The purpose is to provide.

In order to solve the above problems, an X-ray diagnostic imaging apparatus according to the present invention detects X-ray generation means that generates X-rays and transmitted X-rays that have passed through the subject, and X-rays of the transmitted X-rays X-ray detection means for outputting image data indicating intensity, region-of-interest setting means for setting a plurality of regions of interest on an X-ray intensity distribution image based on the image data, and an index indicating the X-ray intensity of each region of interest X-ray intensity calculating means for calculating a representative value, X-ray intensity selecting means for selecting one representative value from representative values of the X-ray intensity of the plurality of regions of interest, and a representative of the selected X-ray intensity X-ray exposure control means for performing exposure control of the X-ray generation means based on the value.

The X-ray exposure control method according to the present invention includes a step of setting a plurality of regions of interest on an X-ray intensity distribution image based on image data indicating the X-ray intensity of transmitted X-rays transmitted through a subject, and each interest Calculating a representative value of an index indicating the X-ray intensity of the region; selecting a representative value from representative values of the X-ray intensity of the plurality of regions of interest; and And X-ray exposure control based on the representative value.

Further, the X-ray exposure control program according to the present invention includes a step of setting a plurality of regions of interest on an X-ray intensity distribution image based on image data indicating the X-ray intensity of transmitted X-rays transmitted through a subject, Calculating a representative value of an index indicating the X-ray intensity of the region; selecting a representative value from representative values of the X-ray intensity of the plurality of regions of interest; and And causing the computer to execute an X-ray exposure control step based on the representative value.

According to the present invention, it is possible to provide an X-ray diagnostic imaging apparatus, an X-ray exposure control method, and a program that can obtain an X-ray intensity corresponding to any part regardless of which part is observed.

Schematic which shows the structure of the X-ray-image diagnostic apparatus which concerns on this embodiment. The block diagram which shows the control system of this embodiment. 6 is a flowchart showing a flow of processing for performing an examination in a fluoroscopic mode by the X-ray image diagnostic apparatus 100 according to the present embodiment. FIG. 4 is a flowchart showing a process flow of step S4 of FIG. Explanatory drawing for demonstrating ROI set by the region-of-interest setting means 7 with which the X-ray-image diagnostic apparatus which concerns on this embodiment is equipped. FIG. 7 is an explanatory diagram for explaining an operation performed by the X-ray intensity calculation means 8 provided in the X-ray image diagnostic apparatus according to the present embodiment, and calculates ROI (patterns (A) to (D)); Explanatory drawing which shows the total pixel number of ROI (pattern 1-5) and pixel value total which can be calculated from the calculated ROI. FIG. 6 is an explanatory diagram for explaining an operation performed by an X-ray intensity calculation means 8 provided in the X-ray image diagnostic apparatus according to the present embodiment, and shows ROI (patterns 6 to 11) that can be calculated from the calculated ROI. Explanatory drawing which shows a total pixel number and pixel value total. Explanatory drawing for demonstrating this embodiment in light of clinical. The perspective view which shows an example of the user interface in the case of applying the function proposed by this invention to a real machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the procedures having the same functions and the same processing contents, and the description thereof will not be repeated.

In the following description, an example in which an X-ray image is captured and displayed using an X-ray diagnostic imaging apparatus that obtains a fluoroscopic image including a moving image of the subject in the fluoroscopic mode will be described. The present invention may be applied to obtain a plurality of still images.

First, the configuration of the X-ray image diagnostic apparatus 100 according to the present embodiment will be described based on FIG. 1 and FIG. FIG. 1 is a schematic diagram showing the configuration of the X-ray image diagnostic apparatus according to the present embodiment. FIG. 2 is a block diagram showing a control system of the present embodiment.

X-ray diagnostic imaging apparatus 100 is an X-ray generation unit 1 that irradiates a subject 12 with X-rays, and is disposed opposite to X-ray generation unit 1 and digital image of X-ray intensity distribution after passing through subject 12 X-ray detection means 2 comprising FPD output as data, image processing means 3 for processing digital image data output from the X-ray detection means 2, and image display for displaying image data output from the image processing means 3 Means 4 and X-ray exposure control means 5 for automatically controlling the X-ray output conditions of the X-ray generation means 1 based on the digital value of the digital image data processed by the image processing means 3.

Further, the X-ray diagnostic imaging apparatus 100 includes an X-ray intensity storage unit 6 for storing a digital value obtained by converting the X-ray intensity of each pixel detected by the X-ray detection unit 2 during fluoroscopy, and an X-ray intensity distribution storage. In the digital image data stored in the means 6, the X-ray intensity is measured, and a plurality of areas (hereinafter referred to as “region of interest” or “ROI”) for calculating a representative value as an index of the X-ray intensity are used. Region of interest setting means 7 to be set, X-ray intensity calculating means 8 for calculating an average value of pixel values of pixels constituting each ROI set by the region of interest setting means 7, and an area of interest X-ray intensity selection means 9 for selecting one average value among the average values of the pixel values of the pixels constituting the ROI of the plurality of patterns set by the setting means 7, and one average by the X-ray intensity selection means 9 X-ray selected by selection condition setting means 10 for setting a condition for selecting a value and X-ray intensity selection means 9 Target X that determines the average value of X-ray intensity, which is the target for the X-ray exposure control means 5 to automatically control the X-ray output conditions, so that the average value of the ROI pixel value that is the index of the degree is kept constant Line intensity setting means 11 and a D / A converter 13 for digital / analog conversion of the digital image data processed by the image processing means 3 are provided.

The X-ray detection means 2 and the image processing means 3, and the image processing means 3, the image display means 4 and the X-ray exposure control means 5 are electrically connected. Further, the X-ray exposure control means 5 is electrically connected to the X-ray generation means 1. The image processing means 3 includes an X-ray intensity distribution storage means 6, an X-ray intensity calculation means 8, and an X-ray intensity selection means 9. The region of interest setting means 7 is electrically connected to the X-ray intensity calculation means 8, the selection condition setting means 10 is electrically connected to the X-ray intensity selection means 9, and the target X-ray intensity setting means 11 is electrically connected to the X-ray exposure control means 5. .

Image processing means 3, X-ray exposure control means 5, X-ray intensity distribution storage means 6, region of interest setting means 7, X-ray intensity calculation means 8, X-ray intensity selection means 9, selection condition setting means 10, and target X-ray The strength setting means 11 is configured by the cooperation of a program module capable of performing each function and hardware resources including a control device, an arithmetic device, a storage device, and an input / output device for executing the program module. Is done.

In this embodiment, the X-ray intensity calculating means 8 calculates the average value of the pixel values of the pixels constituting each ROI as the X-ray intensity, but the X-ray intensity calculating means 8 is an index of the X-ray intensity of each ROI. As another example, the X-ray intensity of each ROI may be calculated using an index using pixel values, for example, the mode value and the median value in addition to the average value of the pixel values.

Next, the operation and principle of the X-ray diagnostic imaging apparatus 100 according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a flow of processing for performing inspection in the fluoroscopic mode by the X-ray image diagnostic apparatus 100 according to the present embodiment. FIG. 4 is a flowchart showing a process flow of step S4 of FIG. FIG. 5 is an explanatory diagram for explaining the ROI set by the region-of-interest setting means 7 provided in the X-ray image diagnostic apparatus 100 according to the present embodiment. FIG. 6A is an explanatory diagram for explaining an operation performed by the X-ray intensity calculation means 8 provided in the X-ray image diagnostic apparatus 100 according to the present embodiment, and calculates ROI (patterns (A) to ( FIG. 4D is an explanatory diagram showing the total number of pixels and the total pixel value of ROI (patterns 1 to 5) that can be calculated from the calculated ROI. FIG.6B is an explanatory diagram for explaining an operation performed by the X-ray intensity calculation means 8 provided in the X-ray image diagnostic apparatus according to the present embodiment, and ROI (pattern 6) that can be calculated from the calculated ROI. FIG. 11 is an explanatory diagram showing the total number of pixels and the total pixel value of (11) to (11). FIG. 7 is an explanatory diagram for explaining the present embodiment in light of clinical practice. FIG. 8 is a perspective view showing an example of a user interface when the function proposed in the present invention is applied to an actual machine. In the following, description will be given along the order of steps in FIG.

(step 1)
Setting is performed by each setting means (S1). More specifically, ROI settings for calculating a value that is an index of X-ray intensity, and selection conditions for selecting one of the values that are an index of X-ray intensity obtained from each ROI, Then, a target value of X-ray intensity (also referred to as “target X-ray intensity”) necessary for obtaining a fluoroscopic image with a desired luminance is set. In this embodiment, since the average value of the pixel values is used as the index value of the X-ray intensity, the target X-ray intensity is also defined using the pixel value.

The X-ray image diagnostic apparatus 100 of this embodiment includes a region of interest setting means 7, a selection condition setting means 10, and a target X-ray intensity setting means 11 as setting means.

Hereinafter, the contents set by each setting means will be specifically described.

The region-of-interest setting means 7 sets an ROI for calculating the X-ray intensity necessary for the X-ray exposure control means 5 to automatically control the X-ray output conditions. There are three main ROIs as shown in FIG. 5A. First, the widest ROI (area 1) to be calculated is set. In the present embodiment, the region 1 is a square closed region at an arbitrary position of the X-ray detection means 4, but the shape is not limited to a square shape, and may be a rectangular shape or a circular shape, and is not particularly limited.

Next, a region 2 and a region 3 are set which are small regions of a rectangular shape that fit within the region 1 and are inscribed in the region 1. Region 2 is a rectangular region that is long in the vertical direction (the horizontal direction in FIG. 5 is referred to as the horizontal direction and the vertical direction is referred to as the vertical direction), and is located near the center in the horizontal direction of region 1. It is a rectangular region that is long in the direction, and is located near the center of the region 1 in the vertical direction.

In this embodiment, the ROI to be set is largely three areas 1 to 3. For example, a rectangular small area that is long in the vertical direction and is inscribed in the area 1 is added to the area 2 in addition to the area 2. It is also possible to make a modification such as further including a rectangular region that is long in the horizontal direction and inscribed in the region 1 in addition to the region 3. In the present embodiment, both the region 2 and the region 3 are configured to be inscribed in the region 1, but the region 2 and the region 3 may be configured to fit in the region 1 without being inscribed. In addition, the area 2 and the area 3 may be small areas that divide the area 1 at an arbitrary ratio.

In this embodiment, assuming that the areas 1 to 3 in FIG. 5A are set in correspondence with the patterns (A) to (D) shown on the left side of FIG. 6A, the eight variables ( N_ (A) to N_ (D) and average value_ (A) to average value_ (D), where N_ (n) is the total number of pixels in pattern (n) and average value _ (n) is the pattern ( n) average value of pixel values), other than the areas set in patterns (A) to (D), that is, the average of patterns 1 to 5 on the right side of FIG. 6A and patterns 6 to 11 of FIG. 6B The value can be calculated. For convenience of explanation, as shown in FIG. 5 (B), the area 2 and the area 3 set in the area 1 are divided into nine small blocks of 3 × 3 by the area 2 and the area 3. From (1), (2), (3), (4), (5), (6), (7), (8), (9) from the upper left to the lower right, the above pattern ( The patterns A) to (D) and the patterns 1 to 11 are composed of the following blocks as shown in Equation 1 below.

[Equation 1]

The variables (N_ (A) to N_ (D) and average value_ (A) to average value_ (D)) obtained from the patterns (A) to (D) are X-ray incident surfaces in the X-ray detection means 2 The X-ray intensity calculation means 8 calculates the number of pixels included in each ROI of the patterns (A) to (D) and the digital value output from the X-ray detection means 2.

The average value of the pixel values of each ROI can be obtained from only the total pixel value and the total number of pixels in the area for which the average value is to be obtained according to the following formula 2. Therefore, the average value of the pixel values of patterns 1 to 11 is calculated by calculating the total pixel value of ROI and the total number of pixels of each pattern using the eight variables, and the calculated total pixel value and the total number of pixels. Can be used to calculate the average ROI of each pattern. The following expression 3 is an expression used for calculating the total number of pixels of the patterns 1 to 11, and the following expression 4 is an expression used for calculating the total pixel value of the patterns 1 to 11. By applying each ROI obtained by the following formula 3 and the following formula 4, that is, the total number of pixels of each pattern and the total pixel value to the following formula 2, the average value of the pixel values of each ROI can be calculated.

[Equation 2]
Average value_ (n) = S_ (n) / N_ (n) (2)
Average value_ (n): Average value of pixel values of pattern (n) S_ (n): Total pixel value of pattern (n) N_ (n): Total number of pixels of pattern (n)

[Equation 3]

[Equation 4]

Instead of setting the small region 2 and the region 3 that fit within the region 1 as shown in FIG. 5 (A) above, the region 2 that fits within the region 1 as shown in FIG. Nine small blocks may be set by using four

dividing lines

40, 41, 42, and 43 in contact with the sides. The dividing lines 40 and 41 are the left side and the right side that are parallel and opposite to the upper side and the lower side of the region 1 (the right side, the left side, the upper side, and the lower side of the region 1 are defined with reference to the horizontal direction and the vertical direction in FIG. 5). Is a line segment that touches The interval between the dividing line 40 and the upper side of the region 1, the interval between the dividing line 40 and the dividing line 41, and the interval between the dividing line 41 and the lower side of the region 1 may be equal or unequal. In the example of FIG. 5B, the interval between the dividing line 40 and the upper side of the region 1 and the interval between the dividing line 41 and the lower side of the region 1 are substantially the same, and the dividing line 40 and the dividing line are separated from those intervals. The distance from the line 41 is set narrow.

Further, the

dividing lines

42 and 43 are line segments that are parallel to the left side and the right side of the region 1 and are in contact with the opposite upper side and lower side. The interval between the left side of the region 1 and the dividing line 42, the interval between the dividing line 42 and the dividing line 43, and the interval between the dividing line 43 and the right side of the region 1 may be equal or unequal.

In the example of FIG. 5A, the interval between the left side of region 1 and the dividing line 42, the interval between dividing line 42 and dividing line 43, and the interval between dividing line 43 and the right side of region 1 are substantially the same. Is set.

The region 1 is divided into nine small blocks (1) to (9) by the

dividing lines

40, 41, 42 and 43 as shown in FIG. By obtaining the total number of pixels and the total pixel value of each block, the average values of the patterns (A) to (D) and the patterns 1 to 11 can be calculated by combining them. As described above, the average values of the patterns (A) to (D) and the patterns 1 to 11 are obtained by calculating eight variables based on the

regions

2 and 3, and the patterns (1) to ( In addition to the method of calculating the average value of 11), a method of calculating the average value of each of the nine small blocks may be used.

The selection condition setting means 10 sets a condition for selecting one average value among the ROIs set by the region of interest setting means 7 and the average values of the other ROIs.

For example, if the X-ray examination details are esophageal and stomach contrast examinations, the X-rays irradiated to the subject will be insufficient or excessive during fluoroscopy due to the effects of direct X-rays and X-ray diaphragms, and appropriate brightness will be achieved. It may be difficult to display a fluoroscopic image.

Specific description will be given with reference to FIG. The figure shows an example of gastric fluoroscopy, the left side of the figure is a schematic diagram of the entire gastric fluoroscopy, and the right side of the figure shows an X-ray image displayed on the image display means 4. In the case of Case 1, in the case of Case 1, the average value of ROI increases directly due to the influence of X-rays, and the X-ray output conditions become low, resulting in blackening of the esophagus. In case 2 and case 3, the average value of ROI decreases due to the influence of the X-ray diaphragm, and the X-ray output conditions increase, so the fluoroscopic image is bright and halation is blurred. Therefore, in order to provide an image having appropriate fluoroscopic brightness without being directly affected by X-rays or an X-ray aperture, it is necessary to select an appropriate ROI as the imaging region moves from the esophagus to the stomach. Therefore, in this embodiment, when it is a fluoroscopic mode that outputs a video signal with a frame rate of 30 frames / sec, ROI may be selected for each frame, ROI is selected for every two frames, etc. Depending on the degree of change in the imaging region and the processing capability of the image processing means 3, the frequency of reselecting the ROI can be arbitrarily set, i.e., calculating the average value of the ROI for any number of frames, and X described later The line output condition may be changed.

In the case of this embodiment, the ROI set by the region of interest setting means 7 and the average values of the plurality of ROIs (patterns 1 to 11) shown in the right side of FIG. 6A and FIG. 6B are always calculated and set as selection conditions. Based on the condition for selecting one average value set by the means 10, the optimum ROI average value is selected for each frame. Since the selected average value is used for X-ray automatic exposure control, it is possible to provide an image having stable perspective brightness.

For example, in case 1 of FIG. 7, the ROI of the pattern (B) in FIG. 6A is selected so that the ROI consisting only of the region where the subject is imaged except the direct X-ray incident region is selected, and case 2 In the case of (3), the ROI of the pattern (B) in FIG.6A is selected so that the ROI consisting only of the area where the subject is imaged is excluded except for the area where the X-ray aperture is imaged. The selection condition setting 10 may be set such that the pattern (D) is selected so that the ROI consisting only of the area where the subject is imaged is excluded except the area where the line aperture is imaged.

That is, when the X-ray examination content is a contrast examination of the esophagus and the stomach, among the average values of the ROI set by the region of interest setting means 7 and other ROIs, the average values other than the maximum and minimum This means that you only have to make a setting to select.

For the selection condition setting contents, for example, 1) Select the ROI that counts from the one with the smallest average value of each ROI, 2) ROI that can select which ROI (in addition to the four ROIs shown on the left side of Fig. 6A) Or put it in the candidate. The selection condition 1) is effective for selecting an ROI excluding an area where direct X-rays are incident and an area where an X-ray aperture is photographed. In addition, the selection conditions in 2) are all 11 patterns 1 to 11 in the right side of FIG. 6A and the example of FIG. 6B by narrowing down ROI candidates according to the X-ray examination content, technique method, and shape of the imaging region. Therefore, it is not necessary to calculate the average value of the pixel values, so that it is possible to expect high speed processing and effective use of hardware resources. Further, as selection conditions, 3) a fixed mode for fixing the position of the ROI with respect to the X-ray incident surface of the X-ray detection means 2 as in the conventional X-ray diagnostic imaging apparatus, and the X-ray exposure control method according to the present embodiment, As in a program, it may be possible to select a change mode in which the position of the ROI with respect to the X-ray incident surface is changed during one fluoroscopy.

In the target X-ray intensity setting means 11, the X-ray exposure control means 5 automatically controls the X-ray output conditions so that the average value of the X-ray intensity selected by the X-ray intensity selection means 9 is kept constant. Determine the average value of the target X-ray intensity.

(Step 2)
X-ray imaging is performed in the fluoroscopic mode, and a video signal is output (S2).
The X-rays irradiated from the X-ray generation means 1 are transmitted as digital image data from the X-ray detection means 2 after passing through the subject 12, and stored and held in the X-ray intensity distribution storage means 6.

(Step 3)
The X-ray intensity distribution image captured in the first frame is output from the X-ray detection means 2 to the image processing means 3 (S3).

(Step 4)
An average value of ROI used in the X-ray exposure control means 5 is calculated (S4).

(Step S41)
The image processing means 3 includes an X-ray intensity distribution storage means 6, an X-ray intensity calculation means 8, and an X-ray intensity selection means 9, and is composed of digital image data output from the X-ray detection means 2. The intensity distribution image is stored and held in the X-ray intensity distribution storage means 6 (S41).

(Step S42)
The X-ray intensity distribution image stored and held in the X-ray intensity distribution storage means 6 is sent to the X-ray intensity calculation means 8. The X-ray intensity calculation means 8 calculates the average value of the pixel values of the ROI set by the region-of-interest setting means 7 and other ROIs (S42).

(Step S43)
The X-ray intensity selection means 9 selects one of the calculated average values of each ROI based on the conditions set by the selection condition setting means 10 and sends the average value to the X-ray exposure control means 5 (S43).

(Step S5)
In addition to the above average value calculation, the digital image data stored and held in the X-ray intensity distribution storage means 6 is an image such as noise reduction processing and display gradation processing, in order to obtain image quality as a diagnostic image. Processing is also performed in the image processing means 3 (S5).

(Step S6)
The D / A converter 13 converts the digital image data subjected to the image processing by the image processing means 3 into an analog signal, and the image processed by the image display means 4 is displayed (S6).

(Step 7)
The X-ray exposure control means 5 determines X-ray output conditions for irradiating the subject in the next frame (S7).
The X-ray exposure control means 5 is the average value of the target X-ray intensity set by the target X-ray intensity setting means 11 and the ROI X in the current frame sent from the X-ray intensity selection means 9 in step S43. The average value of the line intensities is compared, and an X-ray output condition for irradiating the subject in the next frame 12 is determined according to the result.

That is, when the average value of the target X-ray intensity is larger than the average value of the ROI X-ray intensity in the current frame, the X-ray output conditions are increased so as to eliminate the difference. On the other hand, when the average value of the target X-ray intensity is smaller than the average value of the ROI X-ray intensity in the current frame, the X-ray output condition is reduced so as to eliminate the difference. Regarding the increase / decrease of the X-ray output conditions, in the case of continuous fluoroscopy, the tube voltage (kV) and / or tube current (mA), in the case of pulse fluoroscopy, in addition to the tube voltage and tube current, the pulse irradiation width is an adjustment parameter. Conceivable.

(Step S8)
If the inspection is not completed, the process proceeds to step S9. If the inspection is completed, the flow of this process ends (S8).

(Step S9)
The X-ray output condition determined in step S7 is sent to the X-ray generation means 1, and the subject 12 is irradiated with X-rays from the X-ray generation means 1 based on the sent information, and the X-ray detection means 2 Outputs an X-ray intensity distribution image of the next frame (S9). And it returns to step S4 and repeats the process after step S4.

In the above embodiment, the method for automatically selecting the ROI has been mainly described. However, as shown in FIG. 8, the display panel 71, the TV monitor 72 for displaying a fluoroscopic image, the manual setting of the X-ray output condition or the change has been made. Patterns (A) to (D) and patterns 1 to 5 in FIG. 6A and patterns 1 to 5 and FIG. 6B are displayed on the display panel 71 on the remote control console 70 having the X-ray high voltage device operation panel 73 for displaying the X-ray output conditions as needed. Buttons indicating the shapes of the patterns 6 to 11 may be provided so that the user can arbitrarily select the ROI manually. Further, a screen showing the X-ray incident surface of the X-ray detection means 2 is displayed on the display panel 71, and the position, size, and shape of region 1, region 2 and region 3 in FIG. An input setting may be made using a pointing device such as a joystick. Alternatively, the

dividing lines

40, 41, 42, and 43 may be input and set in the region 1 set on the above-described screen. As a result, an ROI having an arbitrary size and shape can be set at an arbitrary position with respect to the X-ray incident surface.

In addition, depending on the region to be inspected, 1) Initially display the recommended positions on the X-ray entrance plane to set each shape (size) of regions 1 to 3 and 2) regions 1 to 3. It may be configured to be arbitrarily changed.

In the above embodiment, the case where FPD is used as the X-ray detection means 2 is described. I. It is also possible to replace with.

1 X-ray generation means, 2 X-ray detection means, 3 image processing means, 4 image display means, 5 X-ray exposure control means, 6 X-ray intensity distribution storage means, 7 X-ray intensity calculation area setting means, 8 X-ray intensity Calculation means, 9 X-ray intensity selection means, 10 Selection condition setting means, 11 Target X-ray intensity setting means, 12 Subject, 13 D / A converter, 70 Remote operator console, 100 X-ray diagnostic imaging device

Claims

X-ray generation means for generating X-rays;
X-ray detection means for detecting transmitted X-rays transmitted through the subject and outputting image data indicating the X-ray intensity of the transmitted X-rays;
Region-of-interest setting means for setting a plurality of regions of interest on the X-ray intensity distribution image based on the image data;
X-ray intensity calculation means for calculating a representative value of an index indicating the X-ray intensity of each region of interest;
X-ray intensity selection means for selecting one representative value from representative values of X-ray intensity of the plurality of regions of interest;
X-ray exposure control means for performing exposure control of the X-ray generation means, based on the representative value of the selected X-ray intensity,
An X-ray diagnostic imaging apparatus comprising:
Target X-ray intensity setting means for setting a target value of the X-ray intensity of the transmitted X-ray detected by the X-ray detection means;
Selection condition setting means for setting a selection condition for selecting one representative value from the representative values obtained from each region of interest;
The X-ray intensity selection means selects the one representative value according to the selection condition,
The X-ray exposure control means compares the selected representative value with the target value, and changes the X-ray output condition so that the difference between the representative value and the target value is reduced. Performing the exposure control,
2. The X-ray image diagnostic apparatus according to claim 1, wherein
During fluoroscopy of the subject,
The X-ray intensity calculation means is configured to calculate each of the regions of interest set with respect to the X-ray intensity distribution image captured in each predetermined number of frames among the frames constituting the video signal obtained during the fluoroscopy. Calculate the representative value of the index indicating the X-ray intensity,
The X-ray intensity selection means selects the one representative value from representative values of an index indicating a plurality of X-ray intensities obtained from the X-ray intensity distribution image captured in each predetermined number of frames. And
The X-ray exposure control means compares the selected representative value with the target value to change the X-ray output condition, and an X-ray intensity distribution image with the one representative value selected is captured. Exposure control to obtain a frame after the frame
3. The X-ray image diagnostic apparatus according to claim 2, wherein
The region-of-interest setting means is based on a closed region at an arbitrary position on the X-ray incident surface in the X-ray detection unit and a plurality of divided regions obtained by dividing the closed region. Setting at least two or more of the region, the divided region, and a region formed by a combination of the divided regions as the region of interest;
2. The X-ray image diagnostic apparatus according to claim 1, wherein
The representative value is either an average value, a mode value, or a median value of pixel values of each region of interest.
5. The X-ray image diagnostic apparatus according to claim 4, wherein
The representative value is an average value of pixel values of each region of interest,
The region-of-interest setting means sets the closed region composed of a rectangular region or a square region, and one or more small regions composed of a rectangular region or a square region inscribed in the closed region, Divide the closed area into two or more divided areas,
The X-ray intensity calculating means, based on the pixel values of the pixels constituting the closed region and the small region, the total number of pixels in the closed region and the total number of pixels in the small region, An average value of pixel values of each region of interest consisting of a small region is calculated, and an average value of pixel values of a region of interest consisting of a divided region different from the small region in the closed region is calculated using the calculated closed region and the calculated region Calculate using the average value of each pixel value of the small region, the total number of pixels constituting the closed region and the total number of pixels constituting the small region,
6. The X-ray image diagnostic apparatus according to claim 5, wherein
The representative value is an average value of pixel values of each region of interest,
The region-of-interest setting means sets the divided region by dividing the closed region into two or more regions by the closed region composed of a rectangular region or a square region, and a dividing line contacting both opposite sides of the closed region. ,
The X-ray intensity calculation means is based on the pixel values of the pixels constituting the closed region and at least one divided region, the total number of pixels in the closed region and the total number of pixels in the at least one divided region, The average value of the pixel values of each region of interest consisting of the closed region and the at least one divided region is calculated, and the pixel value of the region of interest consisting of the divided region or a combination of the divided regions is not subject to the calculation. The average value is calculated by calculating the average value of the pixel values of the closed region and the at least one divided region, the total number of pixels constituting the closed region, and the total number of pixels constituting the at least one divided region. Calculate using
6. The X-ray image diagnostic apparatus according to claim 5, wherein
Further comprising an input means for setting and inputting the closed area, the small area or the dividing line at an arbitrary position on the X-ray incident surface in the X-ray detection means,
7. The X-ray image diagnostic apparatus according to claim 6, wherein
Further comprising an input means for setting and inputting the closed area, the small area or the dividing line at an arbitrary position on the X-ray incident surface in the X-ray detection means,
8. The X-ray image diagnostic apparatus according to claim 7, wherein
The region-of-interest setting means changes at least one of the position, size, and shape of the region of interest in correspondence with the imaging region of the subject.
2. The X-ray image diagnostic apparatus according to claim 1, wherein
The selection condition setting means selects, as the one representative value, a value that is larger than a minimum value and smaller than a maximum value among the plurality of representative values obtained from each region of interest. Set as selection condition,
3. The X-ray image diagnostic apparatus according to claim 2, wherein
Setting a plurality of regions of interest on an X-ray intensity distribution image based on image data indicating the X-ray intensity of transmitted X-rays transmitted through the subject;
Calculating a representative value of an index indicating the X-ray intensity of each region of interest;
Selecting one representative value from representative values of the X-ray intensity of the plurality of regions of interest; and performing X-ray exposure control based on the selected representative value of the X-ray intensity;
An X-ray exposure control method comprising:
Setting a plurality of regions of interest on an X-ray intensity distribution image based on image data indicating the X-ray intensity of transmitted X-rays transmitted through the subject;
Calculating a representative value of an index indicating the X-ray intensity of each region of interest;
Selecting one representative value from representative values of the X-ray intensity of the plurality of regions of interest; and performing X-ray exposure control based on the selected representative value of the X-ray intensity;
X-ray exposure control program characterized in that a computer is executed.