JP2006288554A - X-ray diagnostic apparatus and data generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire diagnostic image data of high image quality in a region of interest and reference image data in a reference region set in the periphery of the region of interest without increasing an X-ray dose to a subject. <P>SOLUTION: An aperture blade 321 of an X-ray movable aperture provided between a subject 150 and an X-ray tube 31 comprises an aperture blade 321a with a prescribed X-ray transmission and an aperture blade 321b completely blocking the X rays, and the position and the size of each aperture opening is arbitrarily set by moving the aperture blades in the direction of arrows (←→). At this time, an imaging region Rxi of a planer detector 21 in an X-ray detecting part is irradiated with high-dose X-rays transmitting through the region of interest Ri of the subject 150, and the imaging region Rxr in the periphery of the imaging region Rxi is irradiated with low-dose X rays transmitting through the reference region Rr of the subject 150 by setting to make the opening by the aperture blade 321b wider than the opening by the aperture blade 321a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray diagnostic apparatus and an image data generation method, and more particularly, to an X-ray diagnostic apparatus and an image data generation method that can reduce the exposure dose to a subject by using an X-ray movable diaphragm.

  Medical image diagnostic technology using an X-ray diagnostic apparatus, MRI apparatus, or X-ray CT apparatus has made rapid progress with the development of computer technology and has become indispensable in today's medical care.

  In recent years, X-ray diagnosis has made progress mainly in the field of circulatory organs with the development of catheter procedures. An X-ray diagnostic apparatus for cardiovascular diagnosis usually includes an X-ray irradiation unit and an X-ray detection unit, a holding mechanism for holding them, a bed (top plate), and a signal processing unit. Then, a suitable imaging position and imaging direction for a patient or the like (hereinafter referred to as a subject) is set by rotating or moving a holding mechanism constituted by a C arm or an Ω arm and a bed. .

The X-ray irradiation unit described above is provided with an X-ray tube that generates X-rays. Further, an X-ray irradiation range is controlled between the X-ray tube and the subject, and the subject is not used. An X-ray movable diaphragm having a diaphragm blade that avoids X-ray exposure and a compensation filter that prevents halation caused by X-rays transmitted through a medium with little absorption is provided. A plurality of slidable diaphragm blades provided in the X-ray movable diaphragm form an opening, and X-rays radiated from the X-ray tube are diagnostic regions of the subject (hereinafter referred to as regions of interest). The size and position of the opening are set so as to selectively irradiate (see, for example, Patent Document 1).
JP-A-4-288146

  So-called IVR (Interventional radiology) is widely performed in which treatment using a catheter or the like is performed under observation of X-ray image data (hereinafter referred to as image data) obtained by the above-described X-ray diagnostic apparatus. With the development of this IVR, a doctor (hereinafter referred to as an operator) can observe the image data of the affected area of the subject displayed on the monitor of the X-ray diagnostic apparatus while setting the distal end of the treatment catheter to a desired site. Since it has become possible to insert and treat, the safety and efficiency of treatment has been dramatically improved.

  In such a case, since it is necessary to observe the region of interest centered on the catheter tip and the affected part of the subject (that is, the site to be treated) in detail, in the conventional IVR, only the region of interest described above is X. The movement control of the diaphragm blades in the X-ray movable diaphragm is performed so that the line is irradiated. Similarly, when a needle biopsy (biopsy test) is performed on a tumor tissue using an X-ray diagnostic apparatus for digestive organs or the like, only X is applied to a region of interest set around the tip of the biopsy needle or the tumor tissue. The diaphragm blades were controlled so that the line was irradiated.

  However, in the above-described IVR, an image around the region of interest (hereinafter referred to as a reference region) is used to grasp the positional relationship between the inserted catheter or biopsy needle and the surrounding organ, confirm the insertion direction, and the like. Data may also be required. In such a case, generation and display of image data for the region of interest and the reference region have been performed by expanding the aperture of the diaphragm blade.

  By the way, it is necessary to generate high-quality image data using a high-dose X-ray for the above-mentioned region of interest, but the image quality is such that the contour of an organ, a catheter, or the like can be captured for the reference region. Therefore, low dose X-rays may be used. However, when a conventional X-ray movable diaphragm is used, it has been impossible to perform high-dose X-ray irradiation on the region of interest and low-dose X-ray irradiation on the reference region at the same time. In the following, when it is desired to observe diagnostic image data and reference area image data (hereinafter referred to as reference image data) at the same time, high-dose X-rays with the aperture of the diaphragm blades expanded. Therefore, there is a problem that the exposure dose to the subject is remarkably increased.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a high-dose X-ray irradiation to a region of interest using an X-ray movable diaphragm and to reduce a reference region around the region of interest. By simultaneously performing X-ray irradiation of a dose, it is possible to obtain high-quality diagnostic image data in the region of interest and extensive reference image data in the reference region without significantly increasing the X-ray exposure dose of the subject. An object is to provide an X-ray diagnostic apparatus and an image data generation method.

  In order to solve the above problems, an X-ray diagnostic apparatus according to the present invention according to claim 1 is an X-ray tube that emits X-rays, and an interest in irradiating a subject with X-rays emitted by the X-ray tube. X-ray diaphragm means for setting an area and a reference area to which the X-ray is attenuated to a predetermined size, X-ray detection means for detecting X-rays transmitted through the region of interest and the reference area, and the X-ray detection means The image data generating means for generating image data based on the X-ray information detected by the line detecting means is provided.

  On the other hand, the image data generation method of the present invention according to claim 13 includes a step of generating image data for a subject using low-dose X-rays, and an interest in the subject under observation of the generated image data. Setting a region and a reference region, selecting a diaphragm blade having a desired X-ray transmittance, moving the selected diaphragm blade based on positional information of the region of interest and the reference region, And irradiating the subject with high-dose X-rays through the diaphragm blades after movement to generate diagnostic image data in the region of interest and reference image data in the reference region. .

  According to the present invention, a high-dose X-ray irradiation to the region of interest using the X-ray movable diaphragm and a low-dose X-ray irradiation to the reference region set around the region of interest are performed simultaneously. Therefore, it is possible to obtain high-quality diagnostic image data in the region of interest and reference image data in the reference region without significantly increasing the X-ray exposure dose to the target region.

  Embodiments of the present invention will be described below with reference to the drawings.

  A feature of the embodiment of the present invention described below is that a first aperture blade whose X-ray transmittance is set to a desired value by two-dimensionally arranging circular holes of a predetermined size at predetermined intervals, and an X-ray Using an X-ray movable diaphragm provided with a second diaphragm blade that is almost completely cut off, it is of interest to irradiate the subject with high-dose X-rays emitted from the X-ray tube and passing through the opening of the first diaphragm blade. An area is set, and a reference area is set by irradiating the subject with low-dose X-rays transmitted through the first diaphragm blade at the opening of the second diaphragm blade.

(Device configuration)
The configuration of the X-ray diagnostic apparatus according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of the X-ray diagnostic apparatus, and FIGS. 2 to 4 are diagrams showing the configuration and functions of an X-ray movable diaphragm provided in the X-ray generator of the X-ray diagnostic apparatus. FIG. 5 is a diagram showing the configuration of the flat detector in the X-ray detector.

  The X-ray diagnostic apparatus 100 in FIG. 1 detects an X-ray generation unit 1 for generating X-rays with respect to the subject 150, two-dimensionally the X-rays transmitted through the subject 150, and the detection result. X-ray detection unit 2 that generates X-ray projection data based on the above, and X-ray irradiation unit 3 and X-ray detection unit 2 of X-ray generation unit 1 (hereinafter collectively referred to as an imaging system) are held. Control of movement of diaphragm blades and the like in an X-ray movable diaphragm 32 (to be described later) of the imaging system and the top plate 10 and the X-ray generation unit 1, a holding unit (not shown), the top plate 10 on which the subject 150 is placed. A moving mechanism unit 6 for performing image data generation, a storage unit 7 for generating and storing diagnostic image data and reference image data based on the X-ray projection data generated by the X-ray detection unit 2, and the image Diagnostic image data generated in the data generation / storage unit 7 and And a display unit 8 for displaying the reference image data.

  Further, the X-ray diagnostic apparatus 100 has an operation unit 9 for setting the X-ray transmittance of the diaphragm blade, setting the movement direction and position of the diaphragm blade, inputting a movement instruction signal, and inputting various commands. And a system control unit 11 that comprehensively controls the above units of the X-ray diagnostic apparatus 100.

  The X-ray generation unit 1 includes an X-ray irradiation unit 3 and a high voltage generation unit 4, and the X-ray irradiation unit 3 includes an X-ray tube 31 and an X-ray movable diaphragm 32. The high voltage generator 42 and the high voltage control unit 41 are provided. The X-ray tube 31 of the X-ray irradiation unit 3 is a vacuum tube that generates X-rays, and accelerates electrons emitted from a cathode (filament) by a high voltage to collide with a tungsten anode to generate X-rays.

  On the other hand, the X-ray movable diaphragm 32 is used for the purpose of reducing the exposure dose to the subject 150 and improving the image quality, and in the subject 150 of the high-dose X-rays emitted from the X-ray tube 31 as shown in FIG. An upper blade (hereinafter referred to as a diaphragm blade) for setting an irradiation region (reference region) Rr in the subject 150 of an irradiation region (region of interest) Ri and a low-dose X-ray attenuated to a predetermined size from the high-dose X-ray. 321). In addition, it has a lower blade 322 that reduces scattered radiation and leakage dose in conjunction with the diaphragm blade 321, a compensation filter 323 that prevents halation by selectively reducing X-rays transmitted through a medium with a small amount of absorption. ing.

  Furthermore, the X-ray movable diaphragm 32 includes a diaphragm blade moving mechanism 324a, a lower blade moving mechanism 324b having a wire rope and a pulley for moving the diaphragm blade 321, the lower blade 322, and the compensation filter 323 to desired positions, and a compensation. A filter moving mechanism 324c is provided.

  Next, the configuration and function of the diaphragm blade 321 which is an important part of the X-ray diagnostic apparatus 100 in the present embodiment will be described in more detail with reference to FIG.

  In FIG. 3, an X-ray tube 31 and a flat detector 21 of the X-ray detection unit 2 described later are disposed to face each other with a subject 150 interposed therebetween, and an X-ray movable restrictor 32 is further provided in front of the X-ray tube 31. Aperture blades 321 are provided. The diaphragm blade 321 includes, for example, a diaphragm blade 321a (first diaphragm blade) having a predetermined X-ray transmittance and a diaphragm blade 321b (second diaphragm blade) that completely blocks X-rays. Each of 321a and aperture blade 321b is connected to the aperture blade moving mechanism 324a of FIG. 2 via a wire rope. The diaphragm blades 321a and 321b described above are configured as a set of four diaphragm blades having substantially the same X-ray transmittance.

  Then, the diaphragm blade moving mechanism 324a moves the diaphragm blade 321a and the diaphragm blade 321b in the direction of the arrow (３) in FIG. 3 to thereby determine the size and position of the high-dose X-ray aperture and the low-dose X-ray aperture. Can be set arbitrarily. At this time, by setting the aperture of the diaphragm blade 321b wider than the aperture of the diaphragm blade 321a, the flat detector 21 passes through the aperture of the diaphragm blade 321a and passes through the region of interest Ri of the subject 150. An imaging region Rxi by high-dose X-rays is formed, and an imaging region by low-dose X-rays that passes through the aperture of the diaphragm blade 321b and passes through the reference region Rr of the diaphragm blade 321a and the subject 150 is formed around the imaging region Rxi. Rxr is formed. In addition, an imaging region Rxc in which X-rays are substantially completely shielded by the diaphragm blades 321b is formed around the imaging region Rxr.

  That is, the above-described imaging region Rxi has high-dose X-rays transmitted through the region of interest Ri of the subject 150, and the imaging region Rxr has low-dose X-rays transmitted through the reference region Rr of the subject 150. Irradiated. The diaphragm blades 321b provided for almost completely shielding X-rays are composed of a lead plate similar to the conventional one.

  Next, a specific example of the diaphragm blade 321a that attenuates high-dose X-rays and converts them to low-dose X-rays will be described with reference to FIG. 4A shows one diaphragm blade 321a, and FIG. 4B shows a part of the diaphragm blade 321a shown in FIG. 4A (for example, a rectangular frame Fa). The lower left end) is shown enlarged. In this case, circular holes Bb having a diameter La are two-dimensionally arranged at intervals Lb in the lead plate Ba of the diaphragm blades 321a, and the X-ray transmittance of the diaphragm blades 321a is determined by the diameters La and the arrangement intervals Lb of the circular holes Bb. Is controlled.

  On the other hand, the X-ray movable diaphragm 32 in FIG. 1 includes a plurality of diaphragm blades 321a having different X-ray transmittances by changing, for example, the diameter La of the circular holes or the arrangement interval Lb, and these diaphragm blades. A diaphragm blade moving mechanism 324a that moves 321a to a desired position is provided. Then, the diaphragm blade moving mechanism 324a selects a set of diaphragm blades 321a having a desired X-ray transmittance based on a control signal supplied from the diaphragm movement control unit 61 of the moving mechanism unit 6 and shown in FIG. Move to the specified position. The diameter of the circular hole in the diaphragm blade 321a is preferably 0.5 mm to 5 mm, but is not particularly limited.

  Next, the high voltage generator 42 of the high voltage generator 4 generates a high voltage to be applied between the anode and the cathode in order to accelerate the thermoelectrons generated from the cathode of the X-ray tube 31, thereby controlling the high voltage. The unit 41 controls the tube current / tube voltage, the irradiation time, the irradiation repetition period, and the like of the high voltage generator 42 based on the X-ray irradiation conditions supplied from the operation unit 9 via the system control unit 11.

  On the other hand, the X-ray detection unit 2 converts the high-dose X-ray that has passed through the region of interest Ri of the subject 150 and the low-dose X-ray that has passed through the reference region Rr into charges and accumulates them. A gate driver 22 for reading out the electric charge accumulated in the detector 21 and a projection data generating unit 20 for generating X-ray projection data from the read out electric charge are provided. The X-ray detection method includes a method for directly converting X-rays into electric charges, and a method for once converting into light and then converting them into electric charges. In the present embodiment, the former will be described as an example. I do not care. Further, instead of the flat detector 21, X-ray I.D. I. A method using may be used.

  As shown in FIG. 5, the flat detector 21 of the X-ray detection unit 2 is configured by two-dimensionally arranging minute detection elements 51 in a column direction and a line direction. The photoelectric film 52 that generates a charge according to the incident X-ray dose, the charge storage capacitor 53 that stores the charge generated on the photoelectric film 52, and the charge stored in the charge storage capacitor 53 are read at a predetermined timing. A TFT (thin film transistor) 54 is provided. In the following, for the sake of simplicity, the configuration of the flat detector 21 in the case where two detection elements 51 are arranged in the column direction (vertical direction in FIG. 5) and in the line direction (horizontal direction in FIG. 5). Will be described.

  In the flat detector 21 shown in FIG. 5, the first terminals of the photoelectric films 52-11, 52-12, 52-21, 52-22, and the charge storage capacitors 53-11, 53-12, 53-21, The first terminal of 53-22 is connected, and the connection point is connected to the source terminals of TFTs 54-11, 54-12, 54-21, 54-22. On the other hand, the second terminals of the photoelectric films 52-11, 52-12, 52-21, 52-22 are connected to a bias power supply (not shown), and charge storage capacitors 53-11, 53-12, 53-21, 53 are connected. The second terminal of -22 is grounded. Further, the gates of the TFTs 54-11 and 54-21 in the line direction are commonly connected to the output terminal 22-1 of the gate driver 22, and the gates of the TFT 54-12 and TFT 54-22 are connected to the output terminal 22-2 of the gate driver 22. Commonly connected.

  On the other hand, the drain terminals of the TFTs 54-11 and 54-12 in the column direction are commonly connected to the signal output line 59-1, and the drain terminals of the TFTs 54-21 and 54-22 are commonly connected to the signal output line 59-2. The signal output lines 59-1 and 59-2 are connected to the projection data generation unit 20. On the other hand, the gate driver 22 supplies a driving pulse for reading to the gate terminal of the TFT 54 in order to read out signal charges generated in the photoelectric film 52 of the detection element 51 and accumulated in the charge storage capacitor 53 by X-ray irradiation. .

  Returning to FIG. 1, the projection data generation unit 20 converts the charge read from the flat detector 21 into a voltage, and converts the output of the charge / voltage converter 23 into a digital signal. An A / D converter 24 and a parallel / serial converter 25 that converts X-ray projection data read out in parallel in units of lines from the flat detector 21 and converted into digital signals into time-series signals are provided. The charge / voltage converter 23 and the A / D converter 24 described above are configured with the same number of channels as the signal output line 59 in the flat detector 21.

  Next, in order to move the flat detector 21 (imaging system) of the X-ray irradiation unit 3 and the X-ray detection unit 2 relative to the subject 150, the moving mechanism unit 6 moves the top 10 to the subject. 150, a top plate moving mechanism 62 that moves in the body axis direction, an imaging system moving mechanism 63 that rotates or moves the imaging system around the subject 150 together with the holding unit, an imaging system moving mechanism 63, and a top plate moving mechanism 62. And a diaphragm movement control unit 61 for controlling the movement of the X-ray movable diaphragm 32 in the X-ray irradiation unit 3.

  The mechanism control unit 64 controls the movement and rotation of the top 10 and the imaging system in accordance with an instruction signal supplied from the operation unit 9 via the system control unit 11, and the X-ray irradiation direction with respect to the subject 150. Set or update the X-ray irradiation position.

  On the other hand, the diaphragm movement control unit 61 has a plurality of sets provided in the X-ray movable diaphragm unit 32 of the X-ray irradiation unit 3 based on the X-ray transmittance of the diaphragm blade 321a that is initially set or updated in the operation unit 9. A set of diaphragm blades 321a having the X-ray transmittance is selected from the diaphragm blades 321a. The diaphragm blades 321b and the diaphragm blade moving mechanism 324a connected to each of the diaphragm blades 321a based on the movement instruction signal of the diaphragm blades 321a supplied from the operation unit 9 via the system control unit 11 are connected to the diaphragm blades. A control signal for moving 321a and diaphragm blade 321b to a desired position is supplied.

  Further, the diaphragm movement control unit 61 performs the lower blade movement mechanism 324b connected to the lower blade 322 and the compensation filter 323 of the X-ray movable diaphragm 32 and the compensation based on the positional information of the diaphragm blade 321a and the diaphragm blade 321b after the movement. A control signal for moving to a predetermined position is also supplied to the filter moving mechanism 324c.

  Next, the image data generation / storage unit 7 has a function of generating image data to be displayed on the display unit 8 and includes a storage circuit and an arithmetic circuit (not shown). The X-ray projection data converted into time-series signals in the line direction by the parallel-serial converter 25 in the projection data generation unit 20 of the X-ray detection unit 2 is sequentially stored in the storage circuit, and diagnostic image data is stored. Then, one piece of image data composed of the reference image data is generated. On the other hand, the arithmetic circuit performs image processing arithmetic on the generated image data for the purpose of contour enhancement, S / N improvement, or the like as necessary.

  On the other hand, the display unit 8 includes a display data generation circuit, a conversion circuit, and a monitor (not shown), and the display data generation circuit corresponds to a predetermined display form for the image data generated by the image data generation / storage unit 7. Conversion processing is performed, and further, display data is generated by synthesizing numbers, various characters, and the like, which are incidental information. Next, the conversion circuit performs D / A conversion and television format conversion on the display data to generate a video signal and display it on the monitor.

  Next, the operation unit 9 is an interactive interface including an input device such as a keyboard, a trackball, a joystick, and a mouse, a display panel, various switches, and the like. The operation unit 9 inputs subject information and controls the diaphragm blades 321a and 321b. Setting of moving direction and moving position and input of movement instruction signal, setting of X-ray transmittance at diaphragm blade 321a, setting of moving direction and moving speed of top plate 10, rotation / movement direction and rotation / movement of imaging system Setting of speed, setting of X-ray irradiation conditions including tube voltage and tube current, and input of various instruction signals are performed.

  Instead of setting the X-ray transmittance in the diaphragm blade 321a, setting of the X-ray irradiation amount in the reference region Rr of the subject 150 or selection of the diaphragm blade 321a having the X-ray transmittance is performed in the operation unit 9. May be.

  The system control unit 11 includes a CPU and a storage circuit (not shown). The system control unit 11 temporarily stores input information, setting information, and selection information supplied from the operation unit 9 in the storage circuit. Each unit is comprehensively controlled to generate and display image data.

(Image data generation procedure)
Next, a procedure for generating image data by the X-ray diagnostic apparatus 100 of this embodiment will be described with reference to the flowchart shown in FIG.

  In the following description, when X-ray imaging is performed on the femoral artery of the subject 150 into which the contrast medium has been injected through the catheter, the catheter is inserted in the preparation imaging mode using low-dose X-rays. Although confirmation and setting of a region of interest and a reference region are performed, and then a region of interest is imaged with high-dose X-rays and a reference region is imaged with low-dose X-rays in the main imaging mode, the present invention is not limited to this.

  In addition, the X-ray transmittance of the diaphragm blade 321a in the X-ray movable diaphragm 32 is set in the operation unit 9, and the diaphragm movement control unit 61 of the moving mechanism unit 6 determines a plurality of sets of diaphragm blades based on the X-ray transmittance. The case where a suitable set of diaphragm blades 321a is selected from among 321a will be described. As described above, the setting of the X-ray irradiation amount in the reference region Rr or the selection of the diaphragm blade 321a having the X-ray transmittance is performed. May be performed in the operation unit 9.

  Prior to the generation of the image data, the operator inputs the subject information in the operation unit 9 of the X-ray diagnostic apparatus 100, sets the X-ray transmittance of the diaphragm blade 321a, and further performs the preparation imaging mode and the main imaging. Initial settings such as X-ray irradiation conditions in the mode are performed (step S1 in FIG. 6). The initial setting information is stored in the storage circuit of the system control unit 11.

  However, here, for the purpose of confirming the insertion state of the catheter for injecting the contrast agent, setting the imaging direction with respect to the subject 150, and further setting the region of interest Ri and the reference region Rr, the image data is obtained with a relatively low dose of X-rays. An imaging mode for generating image data is referred to as a preparation imaging mode, and an imaging mode for generating image data for examination (diagnosis) using high-dose X-rays when the above setting is completed is referred to as a main imaging mode.

  Next, the operator places the subject 150 on the top 10 and further moves or rotates the imaging system constituted by the X-ray irradiation unit 3 and the X-ray detection unit 2 and the top 10 to a suitable position. By doing so, the X-ray irradiation direction with respect to the subject 150 is initialized. When the above initial setting is completed, a shooting start instruction signal for generating image data in the preparation shooting mode is input in the operation unit 9, and this shooting start instruction signal is supplied to the system control unit 11. Thus, the preparatory shooting is started (step S2 in FIG. 6).

  Receiving this imaging start instruction signal, the system control unit 11 reads out the X-ray irradiation conditions in the preparation imaging mode stored in its own storage circuit. Next, this X-ray irradiation condition is supplied to the high voltage controller 41 of the X-ray generator 1, and further, a drive signal for generating X-rays is supplied to the high voltage controller 41.

  The high voltage control unit 41 that has received this drive signal controls the high voltage generator 42 based on the information on the X-ray irradiation conditions and applies a high voltage to the X-ray tube 31 of the X-ray irradiation unit 3. Then, the X-ray tube 31 to which the high voltage is applied irradiates the subject 150 with X-rays for a predetermined period via the X-ray movable diaphragm 32, and the X-rays transmitted through the subject 150 are provided behind the X-ray tube 31. It is detected by the flat detector 21 of the X-ray detection unit 2 thus obtained.

  As shown in FIG. 5, the flat detector 21 includes detection elements 51 that are two-dimensionally arranged in the line direction and the column direction. The detection element 51 receives X-rays that have passed through the subject 150. Then, a signal charge proportional to the X-ray transmission amount is stored in the charge storage capacitor 53 of the detection element 51. When the X-ray irradiation is completed, the gate driver 22 to which the clock pulse is supplied from the system control unit 11 supplies the driving pulse to the flat detector 21 and the signal charge stored in the charge storage capacitor 53 of the detection element 51. Are sequentially read in the column direction.

  The read signal charge is converted into a voltage by the charge / voltage converter 23 in the projection data generation unit 20, and further converted into a digital signal by the A / D converter 24, and then the memory of the parallel / serial converter 25. Are temporarily stored as projection data for one line. Then, the system control unit 11 sequentially reads the stored projection data in line units, stores the projection data in the storage circuit of the image data generation / storage unit 7, and generates two-dimensional image data.

  On the other hand, the arithmetic circuit of the image data generation / storage unit 7 reads out the image data stored in the storage circuit as necessary, and performs image processing arithmetic for the purpose of edge enhancement and S / N improvement. Then, the processed image data is stored again in the storage circuit.

  Next, the display data generation circuit of the display unit 8 reads the image data stored in the storage circuit of the image data generation / storage unit 7 and converts it into a predetermined display format to generate display data. The conversion circuit of the display unit 8 performs D / A conversion and TV format conversion on the display data, and displays the obtained video signal on the monitor.

  In the same manner, the second, third,... Drive signals in the preparation imaging mode are supplied from the system control unit 11 to the high voltage control unit 41 of the X-ray generation unit 1, and based on these drive signals. Then, the X-ray irradiation unit 3, the X-ray detection unit 2, the image data generation / storage unit 7, and the display unit 8 generate image data in the preparation imaging mode for the subject 150 by repeating the same operation as described above, At this time, a plurality of pieces of image data obtained in time series are displayed as real time images on the monitor of the display unit 8 (step S3 in FIG. 6).

  Then, the operator observes the image data of the preparation shooting mode displayed on the display unit 8, and when the shooting direction and shooting position are not appropriate, the operation unit 9 controls the mechanism control unit 64 of the moving mechanism unit 6. Then, an instruction signal for updating the position of the imaging system or the top plate 10 is supplied. The mechanism control unit 64 that has received this instruction signal supplies a drive signal to the imaging system moving mechanism 63 or the top board moving mechanism 62 to update the positions of the imaging system and the top board 10 and is suitable for the subject 150. A shooting position and a shooting direction are set (step S4 in FIG. 6).

  Next, the operator injects a contrast medium from the scale part (base of the foot) of the subject 150 while observing the image data obtained at the updated imaging position and imaging direction and displayed in real time on the monitor of the display unit 8. 6 is inserted (step S5 in FIG. 6), and if it is confirmed that the tip has reached a predetermined site of, for example, the femoral artery, a region of interest of a predetermined size centered on the catheter tip on the image data and A reference area is set (step S6 in FIG. 6).

  That is, the operator sets the positions of the diaphragm blades 321 a and the diaphragm blades 321 b in the X-ray movable diaphragm 32 using the input device of the operation unit 9 while observing the image data generated in the preparation imaging mode. On the other hand, the diaphragm movement control unit 61 of the moving mechanism unit 6 receives the information of the X-ray transmittance initially set by the operation unit 9 from the system control unit 11, and the X-ray movable diaphragm 32 of the X-ray irradiation unit 3. The diaphragm blades 321a having the X-ray transmittance are selected from a plurality of sets of diaphragm blades 321a stored in the screen.

  Next, the diaphragm movement control unit 61 generates a movement control signal based on the positional information of the diaphragm blades 321a and the diaphragm blades 321b received via the system control unit 11, and supplies this movement control signal to the diaphragm blade movement mechanism 324a. The diaphragm blade 321b and the selected diaphragm blade 321a are moved to a predetermined position. At this time, the size and position of the region of interest Ri are determined by the movement of the diaphragm blade 321a, and the size and position of the reference region Rr are determined by the movement of the diaphragm blade 321b.

  When the setting of the region of interest Ri and the reference region Rr is completed in the image data in the preparatory shooting mode, the operator inputs a shooting start instruction signal for generating image data in the main shooting mode in the operation unit 9 (FIG. 6 step S7).

  The system control unit 11 that has received the imaging start instruction signal from the operation unit 9 supplies a drive signal to the high voltage control unit 41 of the X-ray generation unit 1 and has already set the X-ray irradiation conditions in the preparatory imaging mode. Are updated to the X-ray irradiation conditions in the main imaging mode, and the X-ray tube 31 of the X-ray irradiation unit 3 irradiates the subject 150 with X-rays based on the newly set X-ray irradiation conditions.

  Thereafter, the system control unit 11 controls each unit to generate and display image data in the main shooting mode according to the same procedure as the generation and display of image data in the above-described preparation shooting mode (step S8 in FIG. 6). . On the other hand, the operator injects a contrast agent into the femoral artery of the subject 150 using a contrast agent injector (not shown) while observing image data in the main imaging mode displayed in real time on the display unit 8 (FIG. 6). Step S9).

  A plurality of pieces of image data generated in time series in a predetermined period before and after the injection of the contrast agent are stored in the image data generation / storage unit 7 and displayed on the monitor of the display unit 8 in real time.

  If it is necessary to change the region of interest Ri or the reference region Rr or change the X-ray transmittance of the aperture blade 321a during the observation of the image data in the main imaging mode, the operator can It is possible to update by the same procedure as described above.

(Modification)
Next, a modification of the present embodiment will be described with reference to FIG.

  FIG. 7 shows a modification of the diaphragm blade 321a in the X-ray movable diaphragm 32. FIG. 7A shows a single diaphragm blade 321a configured by a strip-shaped X-ray shielding plate Sb arranged one-dimensionally. Is shown. On the other hand, FIG. 7B shows the structure of the diaphragm blades 321a in the rectangular frame Fb of FIG. 7A, and each of the X-ray shielding plates Sb has an angle α with respect to the X-ray irradiation direction. It is set to be inclined. The X-ray transmittance of the diaphragm blade 321a is controlled by the inclination angle α of the X-ray shielding plate Sb.

  On the other hand, the lower end or upper end of the X-ray shielding plate Sb is rotatably connected to the connecting arm Cm, and the end of the connecting arm Cm is connected to the diaphragm blade moving mechanism 324a. The tilt angle α is changed by the rotation of the X-ray shielding plate Sb in the S2 direction accompanying the movement of the connecting arm Cm in the S1 direction, and the X-ray transmittance of the diaphragm blade 321a is changed by the tilt angle α. Be controlled.

  Note that the procedure for setting the region of interest Ri and the reference region Rr by using a combination of the above-described four diaphragm blades 321a is the same as in the above-described embodiment, and thus the description thereof is omitted.

  According to the above-described embodiments of the present invention and modifications thereof, by controlling the X-ray transmittance of the diaphragm blades in the X-ray movable diaphragm, high-dose X-ray irradiation to the region of interest and the surroundings of the region of interest. It is possible to simultaneously perform low-dose X-ray irradiation on the reference region set in (1). Accordingly, high-quality diagnostic image data in the region of interest and reference image data in the reference region can be obtained without significantly increasing the X-ray exposure dose to the subject.

  In particular, when a treatment is performed using a catheter, a puncture needle, or the like while observing image data, the setting of the treatment site in the vicinity of the distal end of the catheter or the puncture needle and the effect of treatment are performed using high-resolution image data obtained in the region of interest. Easily grasp the insertion direction of the catheter or puncture needle, the insertion path, or the positional relationship with the surrounding organs from the reference image data obtained in a relatively wide range of reference areas set around the region of interest. It becomes.

  Also, in the observation of tumors and the like, it is possible to observe the lesion in detail in the diagnostic image data and grasp the positional relationship between the lesion and the surrounding organ in the reference image data.

  FIG. 8 is a diagram for explaining a specific example of the effect of the present embodiment described above. FIG. 8A shows image data P1 obtained by the conventional method with the aperture blade 321a fully opened, and FIG. ) Shows image data P2 in a region of interest set by a conventional diaphragm blade that completely blocks X-rays. On the other hand, FIG. 8C shows the diagnostic image data Pi in the region of interest Ri and the reference image data Pr in the reference region Rr obtained in the above embodiment.

  For example, when generating image data centered on the distal end portion of the catheter indicated by ☆, according to the method of FIG. 8A, high-quality image data is obtained over a wide range, but in all the areas to be imaged. On the other hand, since the high dose X-ray is irradiated, the exposure dose to the subject 150 is large.

  Further, according to the method of FIG. 8B, since the high-dose X-ray irradiation is limited to the region of interest, the exposure dose to the subject 150 is reduced as compared with the method of FIG. Therefore, it is not possible to capture information about the catheter insertion route and surrounding organs.

  On the other hand, according to the method of the present embodiment shown in FIG. 8C, the diagnostic image data Pi obtained by irradiating the region of interest Ri with the high dose X-ray and the low dose X with respect to the reference region Rr. Since the reference image data Pr obtained by irradiating the line is obtained at the same time, it is possible to perform diagnosis using the high-quality diagnostic image data Pi while referring to the reference image data Pr, and the subject 150 The exposure dose to can be reduced as compared with the method of FIG.

  For the reasons described above, according to the present embodiment, the efficiency and accuracy of diagnosis or treatment for the subject 150 and the safety are improved.

  Further, since the diagnostic image data and the reference image data are generated and displayed simultaneously and spatially, the association between the image data is facilitated. Accordingly, the burden on the operator of the X-ray diagnostic apparatus in charge of diagnosis or treatment can be reduced.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to the above-mentioned Example, It can change and implement. For example, in the above-described embodiment, the case where the X-ray imaging is performed on the femoral artery of the subject 150 into which the contrast medium is injected via the catheter has been described. Similar effects can be obtained in X-ray imaging.

  In addition, the region of interest and the reference region are set in the preparatory imaging mode using low-dose X-rays, and then the region of interest is captured with the high-dose X-rays and the reference region is captured with the low-dose X-rays in the main imaging mode. In the present imaging mode, the region of interest and the reference region may be set.

  On the other hand, as a method of controlling the X-ray transmittance in the diaphragm blade 321a, a method (see FIG. 4) for controlling the diameter and arrangement interval of the circular holes arranged two-dimensionally on the lead plate, and a strip-shaped X-ray shielding plate arranged one-dimensionally. Although the method for controlling the tilt angle (see FIG. 7) has been described, the present invention is not limited to these methods. For example, the transmission hole width and the arrangement interval in one-dimensional or two-dimensional lattice-shaped transmission holes are controlled. It may be a method. Moreover, you may control the X-ray transmittance of the material itself used for the aperture blade 321a.

  For example, the diaphragm blade 321b shown in FIG. 9 is made of a lead plate having an X-ray transmittance of 0% as in the conventional case, and the diaphragm blade 321a has an X-ray transmittance of α% (0 <α <100) and It is constituted by two types of X-ray shielding plates Sb1 and Sb2 of β% (0 <β <100). In this case, each of the X-ray shielding plates Sb1 and Sb2 is formed by mixing fine particles such as lead, tin, and tungsten into a base material such as rubber and plastic, and the X-ray transmittance is determined based on the type and concentration of the mixed fine particles. Controlled by.

  That is, the X-ray movable diaphragm 32 of the X-ray irradiation unit 3 stores a plurality of sets of X-ray shielding plates having different X-ray transmittances formed by the above-described method in advance and set by the operation unit 9. Based on the X-ray transmittance of the diaphragm blade 321a, a suitable set or a plurality of sets of X-ray shielding plates are selected from the plurality of sets of X-ray shielding plates.

  According to the method of mixing fine particles described above, spatially uniform low-dose X-rays can be irradiated to the reference region Rr of the subject 150, so that high-quality reference image data can be obtained. In addition, by overlapping a plurality of sets of X-ray shielding plates having different X-ray transmittances, the X-ray transmittance of the diaphragm blade 321a can be controlled accurately and easily.

  Note that one or more sets of X-ray shielding plates having a predetermined X-ray transmittance γ% (γ ≠ 0) may be used instead of the lead plate having an X-ray transmittance of 0% in the diaphragm blade 321b.

1 is a block diagram showing the overall configuration of an X-ray diagnostic apparatus according to an embodiment of the present invention. The figure which shows the structure of the X-ray movable diaphragm in the Example. The figure for demonstrating the structure and function of an aperture blade in the X-ray movable aperture_diaphragm | restriction of the Example. The figure which shows the specific example of the aperture blade in the Example. The figure which shows the structure of the flat detector in the Example. 6 is a flowchart showing a procedure for generating image data in the embodiment. The figure which shows the modification of the aperture blade in the Example. The figure for demonstrating the effect of the Example. The figure which shows the other modification of the aperture blade in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray generation part 2 ... X-ray detection part 3 ... X-ray irradiation part 4 ... High voltage generation part 6 ... Movement mechanism part 7 ... Image data production | generation / storage part 8 ... Display part 9 ... Operation part 10 ... Top plate 11 ... System controller 20 ... Projection data generator 21 ... Plane detector 22 ... Gate driver 23 ... Charge / voltage converter 24 ... A / D converter 25 ... Parallel / serial converter 31 ... X-ray tube 32 ... X-ray movable Aperture 41 ... High voltage control unit 42 ... High voltage generator 61 ... Aperture movement control unit 62 ... Top plate movement mechanism 63 ... Imaging system movement mechanism 64 ... Mechanism control unit 100 ... X-ray diagnostic apparatus 321 ... Aperture blade (upper blade) )
322 ... Lower blade 323 ... Compensation filter 324a ... Aperture blade moving mechanism 324b ... Lower blade moving mechanism 324c ... Compensation filter moving mechanism

Claims (13)

An X-ray tube emitting X-rays;
X-ray diaphragm means for setting a region of interest for irradiating the subject with X-rays emitted by the X-ray tube and a reference region for irradiating the X-ray with attenuation to a predetermined size;
X-ray detection means for detecting X-rays transmitted through the region of interest and the reference region;
An X-ray diagnostic apparatus comprising: image data generation means for generating image data based on X-ray information detected by the X-ray detection means.   The X-ray diaphragm means includes a diaphragm blade moving means and at least one pair of diaphragm blades having a predetermined X-ray transmittance, and the diaphragm blade moving means moves the diaphragm blade to a desired position. The X-ray diagnostic apparatus according to claim 1, wherein a boundary between the region of interest and the reference region is set.   The X-ray diaphragm means includes a plurality of sets of diaphragm blades having X-ray transmittances different from the diaphragm blade selecting means and the diaphragm blade moving means, and the diaphragm blade moving means includes the plurality of sets of diaphragm blade selecting means. A boundary between the region of interest and the reference region is set by moving one or more sets of aperture blades having a desired X-ray transmittance selected from the aperture blades to a desired position. The X-ray diagnostic apparatus according to claim 1.   The X-ray diaphragm means includes a plurality of diaphragm blades having different X-ray transmittances from the diaphragm blade selecting means and the diaphragm blade moving means, and the diaphragm blade moving means includes the plurality of sets of diaphragm blades. 2. The region of interest and the reference region are set by moving at least two sets of diaphragm blades having a desired X-ray transmittance selected from the plurality of diaphragm blades to desired positions. X-ray diagnostic equipment.   The X-ray diaphragm means sets the region of interest by a first diaphragm blade having a predetermined X-ray transmittance, and the reference region by a second diaphragm blade that blocks X-rays from the first diaphragm blade. The X-ray diagnostic apparatus according to claim 4, wherein:   The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diaphragm unit sets the reference region around the region of interest.   The diaphragm blade is composed of an X-ray shielding plate having a plurality of transmission holes arranged one-dimensionally or two-dimensionally, and controls the X-ray transmittance according to at least one of a transmission hole width and an arrangement interval. The X-ray diagnostic apparatus according to any one of claims 2 to 4, wherein   The diaphragm blades have strip-shaped X-ray shielding plates arranged one-dimensionally, and the diaphragm blade moving means changes the inclination angle of the X-ray shielding plate with respect to the X-ray radiation direction to change the X-ray transmission. The X-ray diagnostic apparatus according to any one of claims 2 to 4, wherein the rate is controlled.   5. The X-ray according to claim 2, wherein the aperture blade is formed by mixing fine particles of an element that blocks X-rays into a base material made of a polymer material. Diagnostic device.   The X-ray diagnostic apparatus according to claim 9, wherein the base material is either rubber or plastic.   The X-ray diagnostic apparatus according to claim 9, wherein the fine particles are at least one of lead, tin, and tungsten.   The X-ray detection unit detects X-rays transmitted through the region of interest in the subject and X-rays transmitted through the reference region at substantially the same time, and the image data generation unit detects diagnostic image data in the region of interest. The X-ray diagnosis apparatus according to claim 1, wherein the image data having reference image data in the reference region is generated. Generating image data for a subject using low-dose X-rays;
Setting a region of interest and a reference region for the subject under observation of the generated image data;
Selecting a diaphragm blade having a desired X-ray transmittance;
Moving the selected diaphragm blade based on positional information of the region of interest and the reference region;
Irradiating the subject with high-dose X-rays through the diaphragm blades after movement, and generating diagnostic image data in the region of interest and reference image data in the reference region Image data generation method.

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