JP2005198762A - X-ray diagnosis apparatus and exposure dose controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an irradiation trouble for an examinee by controlling an X-ray irradiation condition to constantly maintain an exposure dose of the X-ray on the examinee within the permissible value. <P>SOLUTION: The exposure dose on the examinee 150 is calculated on the basis of the positional information of an X-ray generating section 1, an X-ray detecting section 2 and the examinee 150 and an area dose detected by an area dosemeter 17 disposed in the above X-ray generating section 1. Then the X-ray dose to be emitted from the X-ray generating section 1 is automatically controlled on the basis of the result of comparison between the calculated exposure dose and the predetermined permissible exposure dose. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an X-ray diagnostic apparatus, and more particularly to an X-ray diagnostic apparatus and an irradiation dose control method that can reduce excessive exposure.

  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 in the 1970s, and is 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. The X-ray diagnosis in the circulatory region is intended for diagnosis of the whole body of arteries and veins including the cardiovascular system, and an X-ray transmission image is often taken in a state where a contrast medium is injected into the blood vessel. An X-ray diagnostic apparatus for cardiovascular diagnosis usually includes an X-ray generation unit and an X-ray detection unit, a holding mechanism for holding them, a bed (top plate), and a signal processing unit. A C-arm or Ω-arm is used as the holding mechanism, and X-ray fluoroscopy from an optimal position and angle is possible for a patient (hereinafter referred to as a subject) by combining with a catheter bed.

  As a detector used in the X-ray detection unit of the X-ray diagnostic apparatus, a normal X-ray I.D. I. (Image Intensifier) is used. This X-ray I.D. I. In the imaging method using X-rays, the X-ray image information obtained by irradiating the subject with X-rays generated from the X-ray tube of the X-ray generation unit and transmitting through the subject is X-ray I.D. I. Is converted into an optical image, which is further converted into an electrical signal by an X-ray TV camera. The X-ray image information converted into the electrical signal is displayed on the monitor after A / D conversion. For this reason, X-ray I.D. I. The image capturing method using can enable real-time image capturing, which was impossible with the film system, and can collect image data with digital signals, thereby enabling various image processing. The X-ray I.V. I. As an alternative, in recent years, two-dimensional array X-ray flat panel detectors have attracted attention, and some of them have already been put into practical use.

  Such an X-ray diagnostic apparatus needs to cause the C-arm to follow the flow of the contrast medium in the blood vessel. For this reason, the imaging system composed of the X-ray generation unit and the X-ray detection unit is moved in a wide range and at high speed. A function is required.

  On the other hand, when the irradiation dose in the above-mentioned X-ray diagnostic apparatus is large, it has hitherto been known that there is a risk of irradiating the living tissue. For example, it has been reported that the incidence of carcinogenesis, hair loss, burns, and fetal malformation increases when the subject is irradiated with intense X-rays. It has become.

  In response to such a demand, in the conventional X-ray diagnostic apparatus, for example, an area dosimeter capable of detecting an X-ray dose is provided in the X-ray generation unit, and calculation is performed based on the area dose obtained by the area dosimeter. There has been a method of displaying the numerical value of the irradiation dose in the subject on the display panel of the display unit or the operation unit. Then, a doctor or a laboratory technician (hereinafter referred to as an operator) who operates the X-ray diagnostic apparatus observes the value of the displayed irradiation X-ray dose, and when it is determined that this value is empirically large, The X-ray irradiation conditions such as the tube voltage and tube current of the X-ray tube provided in the X-ray generator have been updated by manual operation to reduce the irradiation dose.

  However, in the above-described method, only the irradiation dose value in the specimen unit or the image unit is displayed on the display unit or the like, so for the inexperienced operator, the irradiation dose value displayed at this time is the subject. It is extremely difficult to determine whether or not it is within the allowable range, and there is a risk of making a wrong determination. Even for experienced operators, the continuous monitoring of the irradiation dose, which is constantly changing and displayed, can cause a significant reduction in the efficiency of image data collection or diagnosis, and also displays unacceptable values. There was a possibility that you would miss it.

For such conventional problems, based on the area dose detection result by the area dosimeter provided in the X-ray generation unit and the position information of the X-ray generation unit, the X-ray detection unit, the top plate and the subject, etc. The irradiation dose calculated for the subject is compared with the preset allowable dose (hereinafter referred to as the allowable exposure dose), and if this exposure dose exceeds the allowable exposure dose, a warning signal is output. A method of displaying is proposed. (For example, refer to Patent Document 1).
JP 2000-152924 A (page 5-6, Fig. 1-3)

  In the method of Patent Document 1 described above, the comparison between the irradiation dose calculated based on the detection result by the area dosimeter and the preset allowable irradiation dose and the display of the warning signal are automatically performed. Then, the operator can reduce the irradiation dose by updating the X-ray irradiation conditions in accordance with the displayed warning signal, so that the operator is free from the above-mentioned erroneous determination or overlooked problem. .

  However, in the above-described method, the operator who receives the warning signal optimizes the irradiation dose by manual operation. However, the X-ray irradiation conditions for determining the irradiation dose include the X-ray generation unit described above. In addition to the tube voltage and tube current, there are an X-ray pulse width, an irradiation period (rate interval), etc., and the control thereof is extremely complicated. In addition, an X-ray diagnostic apparatus for cardiovascular diagnosis is used, and continuous image data is collected in real time while changing the position and direction of the X-ray generation unit and the X-ray detection unit with respect to the subject. In the case of fluoroscopy, since the irradiation dose also changes constantly, it is extremely difficult to optimize it by manual operation.

  The present invention has been made in view of such problems, and its purpose is to control the X-ray irradiation conditions so that the X-ray irradiation dose in the subject is always kept below the allowable value. An object of the present invention is to provide an X-ray diagnostic apparatus and an irradiation dose control method capable of preventing an irradiation failure on a subject.

  In order to solve the above-described problem, an X-ray diagnostic apparatus according to the first aspect of the present invention includes an X-ray generation unit that irradiates a subject with X-rays, and the subject irradiated with the X-ray generation unit. X-ray detection means for detecting transmitted X-rays, image data generation means for generating X-ray image data for the subject based on the X-rays detected by the X-ray detection means, and the generated X-rays Display means for displaying image data, dose detection means for detecting the radiation dose of X-rays emitted from the X-ray generation means, and irradiation on the subject based on the radiation dose detected by the dose detection means An irradiation dose calculating means for calculating a dose; an irradiation dose comparing means for comparing the irradiation dose calculated by the irradiation dose calculating means with a preset allowable irradiation dose; and It is characterized by comprising a dose control means for controlling the radiation dose of X-rays by the X-ray generating means on the basis of the comparison results obtained by.

  The X-ray diagnostic apparatus of the present invention according to claim 5 is calculated by the irradiation dose calculating means for calculating the irradiation dose in the subject based on the preset X-ray irradiation conditions, and the irradiation dose calculating means. An irradiation dose comparison means for comparing the irradiation dose with a preset allowable irradiation dose, a dose control means for updating the X-ray irradiation condition based on the comparison result obtained by the irradiation dose comparison means, and an update X-ray generation means for irradiating the subject with X-rays based on the X-ray irradiation conditions, and X-ray detection means for detecting X-rays irradiated by the X-ray generation means and transmitted through the subject; And image data generating means for generating X-ray image data for the subject based on the X-rays detected by the X-ray detecting means, and display means for displaying the generated X-ray image data. It is characterized in that was.

  On the other hand, the irradiation dose control method of the present invention according to claim 12 is directed to an X-ray generation means for irradiating a subject with X-rays, an X-ray detection means for detecting X-rays transmitted through the subject, and a detection An irradiation dose control method for an X-ray diagnostic apparatus having an image data generation means for generating X-ray image data based on the generated X-rays, the step of irradiating a subject with X-rays, and radiation A step of detecting an X-ray radiation dose, a step of calculating an irradiation dose in the subject based on the detected radiation dose, and a comparison between the calculated irradiation dose and a preset allowable irradiation dose. And a step of controlling the radiation dose based on the comparison result.

  Furthermore, the irradiation dose control method of the present invention according to claim 13 is an X-ray generation unit that irradiates a subject with X-rays, an X-ray detection unit that detects X-rays transmitted through the subject, and a detection. An irradiation dose control method for an X-ray diagnostic apparatus having an image data generation means for generating X-ray image data based on the generated X-rays, the step of presetting X-ray irradiation conditions for the X-ray generation unit; A step of calculating an irradiation dose in the subject based on the set X-ray irradiation conditions, a step of comparing the calculated irradiation dose with a preset allowable irradiation dose, and the comparison result Updating the X-ray irradiation conditions based on the X-ray irradiation conditions, and irradiating the subject with X-rays based on the updated X-ray irradiation conditions.

  According to the present invention, the optimization of the irradiation dose to the subject is automatically performed by controlling the X-ray irradiation condition based on the comparison result between the calculated irradiation dose in the subject and the preset allowable irradiation dose. As a result, it is possible to collect high-quality image data and prevent X-ray irradiation obstacles on the subject.

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

  The following features of the embodiment of the present invention are the X-ray generation unit, the X-ray detection unit and the position information of the subject, and the area dose detected by the area dosimeter provided in front of the X-ray generation unit. Based on the comparison result between the calculated irradiation dose and the preset allowable irradiation dose, the X-ray dose emitted from the X-ray generation unit is automatically calculated. There is to control.

  In the embodiments of the present invention described below, X-ray fluoroscopy is performed using an X-ray diagnostic apparatus for a circulatory system in which an X-ray generation unit and an X-ray detection unit are held by a C arm, and images continuously collected. Although the case where data is displayed in real time will be described, the present invention is not limited to this. For example, X-ray imaging using a non-circulator device may be used.

  In addition, the above-described area dose and irradiation dose in the present embodiment are both time integral values of the X-ray dose irradiated during a predetermined irradiation time, that is, the cumulative area dose and the cumulative irradiation dose.

(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.

  The X-ray diagnostic apparatus 100 shown in FIG. 1 supplies an X-ray generator 1 for irradiating a subject 150 with X-rays and a high voltage necessary for X-ray irradiation in the X-ray generator 1. The high voltage generation unit 4, the X-ray detection unit 2 that detects X-rays transmitted through the subject 150, the C arm 5 that holds the X-ray generation unit 1 and the X-ray detection unit 2, and a predetermined direction of the C arm 5 And a mechanism unit 3 for controlling the movement of the top plate 18 on which the X-ray detection unit 2 and the subject 150 are placed in a predetermined direction.

  The X-ray diagnostic apparatus 100 stores X-ray image data (hereinafter referred to as image data) generated by the X-ray detection unit 2, and performs image processing and image calculation on the image data. The calculation storage unit 7, the irradiation dose evaluation unit 6 that calculates the irradiation dose in the subject 150 and compares the irradiation dose with the allowable irradiation dose set in advance for each irradiation site or organ, and the above-described image data and irradiation A display unit 8 that displays information on dose or biological effects, an operation unit 9 that performs input of subject information and various commands, and initial settings of X-ray irradiation conditions, fluoroscopic conditions, display conditions, and the like. The system control part 10 which controls each unit of these collectively is provided.

  The X-ray generator 1 includes an X-ray tube 15 that irradiates the subject 150 with X-rays, and an X-ray diaphragm that forms an X-ray weight (cone beam) with respect to the X-rays emitted from the X-ray tube 15. 16 and an area dosimeter 17 for detecting an X-ray dose (radiation dose) that has passed through the X-ray restrictor 16. The X-ray tube 15 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. The X-ray diaphragm 16 has a function of narrowing the X-ray beam emitted from the X-ray tube 15 to a subject 150 and further to a desired irradiation region in the X-ray detector 2.

  The area dosimeter 17 is constituted by a conversion element that converts the X-ray dose emitted from the X-ray tube 15 and passed through the X-ray restrictor 16 into an electric charge. And an area dose output signal substantially proportional to the irradiation time is generated.

  Next, the X-ray detection unit 2 that detects the X-rays irradiated from the X-ray generation unit 1 and transmitted through the subject 150 includes the X-ray I.I. I. And a method using a so-called X-ray flat panel detector in which X-ray detectors are two-dimensionally arranged. In the following, X-ray I.D. I. A method using X-rays will be described, but a method using an X-ray flat panel detector may be used. In other words, the X-ray detection unit 2 performs X-ray I.D. I. 21, an X-ray television camera 22, and an A / D converter 23. X-ray I.D. I. 21 converts X-rays transmitted through the subject 150 into visible light, and further multiplies luminance in the process of light-electron-light conversion to form highly sensitive projection data. On the other hand, the X-ray television camera 22 converts the above-mentioned optical projection data into an electrical signal using a CCD image pickup device, and the A / D converter 23 performs time-series output from the X-ray television camera 22. An electric signal (video signal) is converted into a digital signal.

  Next, the mechanism unit 3 moves the subject 150 in the body axis direction (direction perpendicular to the paper surface of FIG. 1), the direction perpendicular to the body axis direction (left and right direction in FIG. 1), and the vertical direction (in FIG. 1). And the C-arm 5 that holds the X-ray generator 1 and the X-ray detector 2, and the C-arm 5 that holds the X-ray generator 1 and the X-ray detector 2. And an imaging system moving mechanism 31 that moves the X-ray detector 2 in the direction of the subject and a mechanism control circuit 33 that controls these moving mechanisms. .

  The mechanism control circuit 33 controls the imaging system moving mechanism 31 according to the control signal supplied from the system control unit 10, and the direction, size, or speed in the rotation / movement of the C arm 5 and the X-ray detection unit 2. Further, information on the rotation angle and the moving distance at this time is supplied to the irradiation dose evaluation unit 6.

  FIG. 2 is a diagram for explaining the rotation / movement direction of the X-ray generation unit 1 and the X-ray detection unit 2 by the imaging system movement mechanism 31 and the movement direction of the top board 18 by the top board movement mechanism 32. In FIG. 2, the imaging system moving mechanism 31 is held on a gantry (not shown) so as to be rotatable in the R1 direction about an axis perpendicular to the body axis direction of the subject 150. Further, the C-arm 5 is slidably attached to the imaging system moving mechanism 31 in the R2 direction, and an X-ray generation unit 1 and an X-ray detection unit 2 are provided in the vicinity of both ends of the C-arm 5. Yes.

  Then, the X-ray generation unit 1 and the X-ray detection unit 2 rotate the C arm 5 in the R1 direction so that the affected part (for example, the heart) of the subject 150 becomes the rotation center (isocenter) of the X-ray beam. CRA) and tail direction (CAU). Furthermore, the X-ray generation unit 1 and the X-ray detection unit 2 rotate in the R2 direction of the C arm 5 so that the first oblique position (RAO) and the second oblique position are centered on the isocenter of the subject 150. It also rotates relative to the direction (LAO). That is, the X-ray generation unit 1 and the X-ray detection unit 2 rotate in the directions of RAO, LAO, CRA, and CAU as the C-arm 5 rotates. X-ray fluoroscopy is possible. The imaging system moving mechanism 31 moves the X-ray detector 2 in the R3 direction, and the X-ray I.D. I. 21 is set to a desired distance with respect to the body axis center (or affected part) of the subject 150.

  On the other hand, the top plate 17 is moved in the R4 direction, the R5 direction (direction perpendicular to the paper surface of FIG. 2), and the R6 direction (left-right direction in FIG. 2) by a top plate moving mechanism 32 (not shown). In particular, the X-ray irradiation area in the subject 150 changes due to the movement in the R4 direction, and the value of the irradiation dose in the subject also changes with the change in the irradiation area. Details of these will be described later. .

  Returning to FIG. 1, the high voltage generator 4 includes a high voltage generator 42 that generates a high voltage to be applied between the anode and the cathode in order to accelerate the thermal electrons generated from the cathode of the X-ray tube 15; In accordance with an instruction signal from the system control unit 10, high voltage control for controlling X-ray irradiation conditions including a tube current, a tube voltage, an X-ray pulse width, an irradiation period (rate interval), a fluoroscopic section, and the like in the high voltage generator 42. A circuit 41 is provided.

  FIG. 3 shows the drive timing of X-ray irradiation in X-ray fluoroscopy in a predetermined direction, and X-ray irradiation with the X-ray pulse width τ1 is repeated N times at the irradiation cycle τ2 in the minimum fluoroscopic interval τx. In this case, the irradiation time τr is determined by τr = N · τ1. The vertical axis in FIG. 3 corresponds to the magnitude of the tube voltage or tube current in the X-ray tube 15 of the high voltage generator 4.

  Next, the irradiation dose evaluation unit 6 of FIG. 1 includes an irradiation dose calculation circuit 61 and an irradiation dose comparison circuit 62. This irradiation dose calculation circuit 61 is based on the position information of the X-ray generation unit 1, the top plate 18, etc. supplied from the mechanism control circuit 33 of the mechanism unit 3 via the system control unit 10. A distance Lx between the X-ray tube 15 and the fluoroscopic target region of the subject 150 is calculated, and further, the calculated fluoroscopic distance Lx and the area dose Is supplied from the area dosimeter 17 of the X-ray generation unit 1 to the fluoroscopic target region. An irradiation dose Ix per unit area to be irradiated is calculated.

An example of the method for calculating the irradiation dose is shown in FIG. Here, in order to simplify the description, a case where X-rays are irradiated from the front direction of the subject 150 will be described. That is, as shown in FIG. 4, the irradiation angle is set to α degrees by the X-ray diaphragm 16 (not shown) of the X-ray generator 1, and at this time, the subject is removed from the X-ray tube 15 (not shown) of the X-ray generator 1. If the distance to 150 is Lx, the area S of the X-ray irradiation region 151 in the subject 150 is S = π (Lx · tan (α / 2)) ² . However, the irradiation angle α is set as one of the X-ray irradiation conditions, and the distance Lx is calculated from the positional information of the X-ray generation unit 1 and the top board 17.

  On the other hand, the area dosimeter 17 radiates from the X-ray tube 15 in a predetermined period (for example, the fluoroscopic section τx shown in FIG. 3), and the total dose of X-rays passing through the chamber of the area dosimeter 17 is time-integrated. The area dose Is is measured. At this time, since the X-ray energies in the irradiation area 151 of the area dosimeter 17 and the subject 150 are equal, the irradiation dose Ix per unit area of the irradiation area 151 can be obtained by Ix = Is / S.

  Next, the irradiation dose comparison circuit 62 compares the irradiation dose Ix in the irradiation region of the subject 150 calculated by the irradiation dose calculator 61 with a preset allowable irradiation dose Iy, and the irradiation dose Ix is allowed to be irradiated. When the dose is larger than the dose Iy, the difference ΔI = Ix−Iy is supplied to the system control unit 10. Since the influence of X-ray irradiation on the living body varies depending on the site or organ irradiated with X-ray, it is desirable that the allowable irradiation dose Iy is set in advance for each of the fluoroscopic target site or the fluoroscopic target organ.

  FIG. 5 shows the permissible irradiation dose Iy for each fluoroscopic target region stored in advance in a storage circuit (not shown) of the irradiation dose comparison circuit 62. The fluoroscopic target region or the imaging target region is the head, heart, chest. In the case of..., The allowable irradiation dose Iy is set based on, for example, guidelines issued by the Japan Radiation Engineers Association. The setting of the allowable irradiation dose for the fluoroscopic target organ or the radiographic target organ is performed in the same manner. Further, in this memory circuit, information on biological effects (irradiation failure) that occurs when the irradiation dose at the fluoroscopic part (organ) or the imaging part (organ) becomes significantly larger than the allowable irradiation dose is stored in advance. .

  Returning to FIG. 1 again, the image calculation storage unit 7 has a function of generating image data to be displayed on the display unit 8, and includes an image data storage circuit 71 and an image calculation circuit 72. The image data storage circuit 71 sequentially accumulates electrical signals supplied in time series from the A / D converter 23 of the X-ray detection unit 2 to generate image data, and performs image computation on the image data. The image data after the image calculation obtained by the image calculation and image processing performed by the circuit 72 is temporarily stored.

  The image calculation circuit 72 uses the image data supplied from the X-ray detection unit 2 and temporarily stored in the image data storage circuit 71, for example, DSA image data or road map image data by subtraction between image data before and after contrast agent injection. Then, image processing for generating long image data and the like, and image processing such as contour enhancement and smoothing, and gradation change are performed on the obtained image data.

  Next, the operation unit 9 is an interactive interface including an input device such as a keyboard, a trackball, a joystick, a mouse, a display panel, or various switches. The operation unit 9 inputs object information, the rotation angle of the X-ray generation unit 1 and the X-ray detection unit 2 (that is, the X-ray irradiation direction), and the movement distance of the X-ray detection unit 2 and the top plate 18. , X-ray irradiation angle α by X-ray restrictor 16, X-ray I.V. I. The projection range in 21 is set, and various commands are input, and the initial setting of X-ray irradiation conditions for the fluoroscopic target organ is performed. The X-ray irradiation conditions include the tube current, tube voltage, X-ray pulse width, irradiation period (rate interval), fluoroscopic section, irradiation time, etc. already shown in FIG. 3, and subject information includes age, sex, There are body type (height and weight), fluoroscopic target site (organ), past diagnosis history, and the like.

  The display unit 8 is for displaying the image data stored in the image data storage circuit 71 of the image calculation storage unit 7 and the irradiation dose in the subject 150 obtained in the irradiation dose evaluation unit 6. A display data generation circuit 81 that generates display image data by combining data and information on irradiation dose that is incidental information, and D / A conversion and TV format conversion are performed on the display image data. A conversion circuit 82 for generating a video signal and a liquid crystal or CRT monitor 83 for displaying the video signal are provided.

  The system control unit 10 includes a CPU and a storage circuit (not shown), and various input information and setting conditions in the operation unit 9 are stored in the storage circuit. For example, the rotation / movement information and the X-ray irradiation conditions of the X-ray generation unit 1, the X-ray detection unit 2, and the top plate 18 that are initially set in the operation unit 9 are stored in the storage circuit and then supplied to the unit. .

  Further, the system control unit 10 in the present embodiment updates the already set X-ray irradiation conditions based on the comparison result ΔI supplied from the irradiation dose comparison circuit 62 of the irradiation dose evaluation unit 6. In this case, the storage circuit previously stores a correction value of the tube voltage, tube current, X-ray pulse width τ1 or irradiation period τ2 corresponding to the comparison result ΔI as a lookup table. The system control unit 10 that has received the comparison result ΔI from the irradiation dose comparison circuit 62 reads out the correction value for making the comparison result ΔI zero or less, and based on this correction value, the X-ray irradiation condition Update.

(Irradiation dose control procedure)
Next, an irradiation dose control procedure in the X-ray diagnostic apparatus 100 of the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing the irradiation dose control procedure.

  The operator inputs subject information regarding the subject 150 and sets initial X-ray irradiation conditions in the operation unit 9, and further detects the rotation angles of the X-ray generation unit 1 and the X-ray detection unit 2 and the X-ray detection. By inputting the moving distance of the unit 2 or the top plate 18, the initial setting of the fluoroscopic direction and fluoroscopic position is performed. (Step S1 in FIG. 6). These initial setting conditions are stored in the storage circuit of the system control unit 10.

  In addition to the subject ID, the fluoroscopic region “abdomen” and the like are input as the subject information, and the tube voltage “Vo”, the tube current “Io”, the X-ray pulse width “τ1”, and the irradiation period are set as the X-ray irradiation conditions. “Τ2”, the number of fluoroscopy “N”, and the like are input.

  When the above initial setting is completed, the operator inputs an X-ray fluoroscopic start command in the operation unit 9. Then, the fluoroscopic start command signal is supplied to the system control unit 10 to start X-ray fluoroscopy (step S2 in FIG. 6).

  The system control unit 10 that has received the X-ray fluoroscopic start command signal supplies a rotation / movement instruction signal to the mechanism control circuit 33 of the mechanism unit 3 based on the initial setting information. Upon receiving this instruction signal, the mechanism control circuit 33 supplies a control signal to the imaging system moving mechanism 31 and the top plate moving mechanism 32 to rotate the C arm 5 in a predetermined direction by a predetermined angle, and to perform X-rays. The detection unit 2 or the top plate 18 is moved to a predetermined position (step S3 in FIG. 6).

  When the rotation of the C-arm 5 and the movement of the X-ray detector 2 or the top plate 18 are finished, X-ray fluoroscopy is started. During X-ray fluoroscopy, the high voltage control circuit 41 of the high voltage generator 4 receives an X-ray irradiation command from the system controller 10 and controls the high voltage generator 42 based on already set X-ray irradiation conditions. Then, the high voltage “Vo” is applied to the X-ray tube 15 of the X-ray generator 1. Next, the X-ray tube 15 to which the high voltage “Vo” is applied irradiates the subject 150 with X-rays having a pulse width “τ1” via the X-ray restrictor 16 and the area dosimeter 17 (step of FIG. 6). S4). Then, the X-ray transmitted through the subject 150 is converted into the X-ray I.D. I. 21 is projected.

  On the other hand, X-ray I.D. I. 21 converts the X-rays transmitted through the subject 150 into an optical image, and the X-ray TV camera 22 converts the optical image into an electrical signal (video signal). The video signal output in time series from the X-ray television camera 22 is converted into a digital signal by the A / D converter 23 and then sequentially stored in the image data storage circuit 71 in the image calculation storage unit 7. Thus, image data (image data before image calculation) is generated.

  Next, the image calculation circuit 72 of the image calculation storage unit 7 reads the image data stored in the image data storage circuit 71 and, if necessary, performs image processing such as contour enhancement and gradation change, and before contrast agent injection. Image operations such as subtraction with previously obtained image data (reference image data) are performed. Then, the image data after the image calculation / processing is once stored in the image data storage circuit 71 again (step S5 in FIG. 6).

  Next, the image data storage circuit 71 of the image calculation storage unit 7 supplies the stored image data to the display data generation circuit 81 of the display unit 8, and the display data generation circuit 81 controls the image data and the system control. The image data for display is generated by synthesizing the incidental information (for example, subject ID, fluoroscopic direction, X-ray irradiation condition) of the image data supplied from the unit 10. Then, the conversion circuit 82 performs D / A conversion and TV format conversion on the display image data, generates a video signal, and displays it on the monitor 83 (step S6 in FIG. 6).

  Further, by repeating the same procedure as described above N times at intervals of the irradiation period (τ2), N pieces of continuous image data in a predetermined fluoroscopic direction are generated, and these generated image data are displayed on the monitor of the display unit 8. A real-time display is performed at 83 (steps S4 to S7 in FIG. 6).

  On the other hand, when the N pieces of image data are generated, the area dose meter 17 of the X-ray generator 1 sequentially accumulates the area dose of X-rays emitted from the X-ray tube 15. Then, the area dose (cumulative area dose) Is accumulated during the X-ray irradiation time τr (τr = N · τ1) is supplied to the irradiation dose calculation circuit 61 of the irradiation dose evaluation unit 6 (step S8 in FIG. 6). ).

  Next, the irradiation dose calculation circuit 61 of the irradiation dose evaluation unit 6 determines the X-ray generation unit 1 based on the positional information of the X-ray generation unit 1 and the top board 18 supplied from the mechanism control circuit 33 of the mechanism unit 3. A distance Lx between the X-ray tube 15 and the fluoroscopic target portion of the subject 150 is calculated. Further, from the calculated distance Lx and the area dose Is supplied from the area dosimeter 17 of the X-ray generator 1, an irradiation dose Ix per unit area irradiated to the fluoroscopic target portion of the subject 150 is calculated and irradiated. The dose is supplied to the dose comparison circuit 62 (step S9 in FIG. 6).

  On the other hand, the irradiation dose comparison circuit 62 reads the allowable irradiation dose Iy corresponding to the fluoroscopic target portion “abdomen” supplied from the operation unit 9 as the subject information and supplied via the system control unit 10 from the storage circuit. Then, a difference value ΔI (ΔI = Ix−Iy) between the allowable irradiation dose Iy and the irradiation dose Ix supplied from the irradiation dose calculation circuit 61 is calculated, and the comparison result ΔI is supplied to the system control unit 10 (FIG. 6 step S10).

  Then, the system control unit 10 updates the X-ray irradiation conditions based on the magnitude and sign of the comparison result supplied from the irradiation dose comparison circuit 62. That is, when the difference value ΔI is positive (ΔI> 0) (step S11 in FIG. 6), the CPU of the system control unit 10 determines the tube voltage, tube current, and X-ray pulse width corresponding to the difference value ΔI. The correction value of either τ1 or irradiation period τ2 is read from the storage circuit, and the already set X-ray irradiation conditions are updated by this correction value (step S12 in FIG. 6).

  Next, the system control unit 10 supplies the mechanism control circuit 33 with a rotation / movement instruction signal for performing X-ray fluoroscopy in the same fluoroscopic direction or different fluoroscopic directions based on the initial setting information. The mechanism control circuit 33 rotates the C-arm 5 in a predetermined direction by a predetermined angle and moves the X-ray detector 2 or the top plate 18 to a predetermined position. On the other hand, the high voltage control circuit 41 of the high voltage generation unit 4 controls the high voltage generator 42 based on the updated X-ray irradiation condition supplied from the system control unit 10 and supplies the high voltage to the X-ray generation unit 1. The X-ray tube 15 is applied. Thereafter, image data is generated and displayed in the same procedure as described above (steps S3 to S12 in FIG. 6).

  In the above embodiment, as already described, the image data generated by X-ray fluoroscopy with respect to the subject 150 is displayed in real time on the monitor 83 of the display unit 8. By displaying the information of the irradiation dose Ix in the operator, the operator can constantly monitor whether or not the X-ray irradiation conditions are normally updated.

  FIG. 7 is a display example of the irradiation dose Ix and the allowable irradiation dose Iy. FIG. 7A includes, for example, an image data display area 91, a patient information display area 92, and an X-ray irradiation condition display area 93. 7B shows details of the X-ray irradiation condition display area 93. FIG.

  That is, in the X-ray irradiation condition display area 93 in FIG. 7B, the latest values of the X-ray irradiation conditions such as the tube voltage, the tube current, and the X-ray pulse width, which are sequentially updated, are displayed. The latest value 95 of the irradiation dose Ix for the safe area 96 and the dangerous area 97 with the value 94 of the allowable dose Iy as a boundary is displayed in a graph. Each value of the allowable irradiation dose Iy and the irradiation dose Ix may be displayed numerically.

  According to the present embodiment described above, when X-ray fluoroscopy is performed on a subject and continuous image data is displayed in real time, based on a comparison result between an irradiation dose on the subject and a preset allowable irradiation dose. Thus, by updating the X-ray irradiation conditions, it is possible to automatically optimize the irradiation dose in the subject. For this reason, the operator does not have to determine whether or not the irradiation dose is within the allowable range, and is freed from complicated updating of the X-ray irradiation conditions.

  That is, according to the present embodiment, it is possible not only to reliably prevent an irradiation failure on the subject, but also to improve the efficiency of image data generation and diagnosis performed by the operator.

  In addition, since the allowable irradiation dose in the above-described embodiment is set in advance for each fluoroscopic region or for each fluoroscopic organ, the optimal irradiation dose for the subject can be set accurately. Furthermore, when the irradiation dose is remarkably smaller than the allowable irradiation dose, it is possible to generate image data excellent in S / N by updating the X-ray irradiation conditions so as to increase the irradiation dose. .

  Furthermore, the operator can always confirm that the X-ray irradiation conditions are correctly updated by monitoring the irradiation dose that changes with the change of the X-ray irradiation conditions on the display unit or the operation unit. It becomes possible.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to said Example, It can change and implement. For example, in the above embodiment, the irradiation dose in the subject is calculated based on the area dose value detected by the surface dosimeter provided in the X-ray generation unit 1, but the dose detector other than the area dosimeter is used. May be. The irradiation dose may be theoretically obtained based on X-ray irradiation conditions, X-ray tube structure data, position information of the X-ray generation unit and the subject, and the like.

  On the other hand, in the description of the above embodiment, the X-ray fluoroscopy has been described. However, the present invention is not limited to this, and the present invention can be applied to normal X-ray imaging. Furthermore, the X-ray diagnostic apparatus to which the present invention is applied is not limited to the circulatory system.

  Moreover, although the case where the allowable irradiation dose is set for each region has been described, it may be for each organ.

  Further, the list of X-ray irradiation conditions shown in FIG. 7 or the graph of irradiation dose and allowable irradiation dose may be displayed on the display panel in the operation unit. Further, when the irradiation dose exceeds the allowable irradiation dose, a warning signal may be displayed by blinking LEDs or acoustic means, or the biological effect information shown in FIG. 5 may be displayed.

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 rotation / movement direction of the X-ray generation part in the same Example, an X-ray detection part, and a top plate. The figure which shows the X-ray irradiation timing in the X-ray fluoroscopy of the Example. The figure for demonstrating the calculation method of the irradiation dose in the Example. The figure which shows the specific example of the permissible irradiation dose according to the fluoroscopy part previously stored by the irradiation dose comparison circuit of the Example. The flowchart which shows the control procedure of the irradiation dose in the Example. The figure which shows the example of a display of the irradiation dose and allowable irradiation dose in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray generation part 2 ... X-ray detection part 3 ... Mechanism part 4 ... High voltage generation part 5 ... C arm 6 ... Irradiation dose evaluation part 7 ... Image calculation memory | storage part 8 ... Display part 9 ... Operation part 10 ... System control Part 15 ... X-ray tube 16 ... X-ray restrictor 17 ... Area dosimeter 18 ... Top plate 21 ... X-ray I.D. I.
22 ... X-ray TV camera 23 ... A / D converter 31 ... Imaging system moving mechanism 32 ... Top plate moving mechanism 33 ... Mechanism control circuit 41 ... High voltage control circuit 42 ... High voltage generator 61 ... Irradiation dose calculation circuit 62 ... Irradiation dose comparison circuit 71 ... Image data storage circuit 72 ... Image operation circuit 81 ... Display data generation circuit 82 ... Conversion circuit 83 ... Monitor 100 ... X-ray diagnostic apparatus 150 ... Subject

Claims (13)

X-ray generation means for irradiating the subject with X-rays;
X-ray detection means for detecting X-rays irradiated by the X-ray generation means and transmitted through the subject;
Image data generation means for generating X-ray image data for the subject based on the X-rays detected by the X-ray detection means;
Display means for displaying the generated X-ray image data;
A dose detection means for detecting a radiation dose of X-rays emitted from the X-ray generation means;
An irradiation dose calculating means for calculating an irradiation dose in the subject based on the radiation dose detected by the dose detecting means;
An irradiation dose comparing means for comparing the irradiation dose calculated by the irradiation dose calculating means with a preset allowable irradiation dose;
An X-ray diagnostic apparatus comprising a dose control means for controlling an X-ray radiation dose by the X-ray generation means based on a comparison result obtained by the irradiation dose comparison means.   The X-ray diagnostic apparatus according to claim 1, wherein the dose detection unit detects an area dose of X-rays emitted from the X-ray generation unit.   The irradiation dose calculation means is based on the area dose detected by the dose detection means and the position information of at least one of the X-ray generation means, the X-ray detection means, and the subject detected by the position information detection means. The X-ray diagnostic apparatus according to claim 1, wherein an irradiation dose in the subject is calculated.   The irradiation dose calculation means calculates an irradiation dose per unit area of the subject based on the radiation dose obtained by the dose detection means and distance information between the subject and the X-ray generation means. The X-ray diagnostic apparatus according to claim 1, wherein: An irradiation dose calculating means for calculating an irradiation dose in the subject based on preset X-ray irradiation conditions;
An irradiation dose comparing means for comparing the irradiation dose calculated by the irradiation dose calculating means with a preset allowable irradiation dose;
A dose control means for updating the X-ray irradiation conditions based on the comparison result obtained by the irradiation dose comparison means;
X-ray generation means for irradiating the subject with X-rays based on the updated X-ray irradiation conditions;
X-ray detection means for detecting X-rays irradiated by the X-ray generation means and transmitted through the subject;
Image data generation means for generating X-ray image data for the subject based on the X-rays detected by the X-ray detection means;
An X-ray diagnostic apparatus comprising display means for displaying the generated X-ray image data.   The irradiation dose calculation means is based on X-ray irradiation conditions for the X-ray generation means and position information of at least one of the X-ray generation means, the X-ray detection means, and the subject detected by the position information detection means. The X-ray diagnostic apparatus according to claim 5, wherein an irradiation dose in the subject is calculated.   The irradiation dose comparison unit compares the irradiation dose calculated by the irradiation dose calculation unit with an allowable irradiation dose set in advance corresponding to a diagnosis target region or a diagnosis target organ in the subject. The X-ray diagnostic apparatus according to claim 1 or 5.   The dose control unit updates at least one of a tube voltage, a tube current, an X-ray pulse width, an irradiation period, and a fluoroscopic section of a drive signal supplied to the X-ray generation unit. Item 6. The X-ray diagnostic apparatus according to Item 5.   The X-ray diagnostic apparatus according to claim 1, wherein the display unit synthesizes and displays the information regarding the irradiation dose and the allowable irradiation dose and the X-ray image data.   The X-ray diagnostic apparatus according to claim 1, wherein the display unit displays information on the irradiation dose and the allowable irradiation dose and the X-ray image data in real time.   6. The X-ray diagnostic apparatus according to claim 1, further comprising warning signal generation means for generating a warning signal when the irradiation dose is larger than the allowable irradiation dose. X-ray generation means for irradiating the subject with X-rays, X-ray detection means for detecting X-rays transmitted through the subject, and image data for generating X-ray image data based on the detected X-rays An irradiation dose control method for an X-ray diagnostic apparatus having a generating means,
Irradiating the subject with X-rays;
Detecting the radiation dose of emitted X-rays;
Calculating an irradiation dose in the subject based on the detected radiation dose;
Comparing the calculated irradiation dose with a preset allowable irradiation dose;
Irradiation dose control means comprising a step of controlling the radiation dose based on the comparison result. X-ray generation means for irradiating the subject with X-rays, X-ray detection means for detecting X-rays transmitted through the subject, and image data for generating X-ray image data based on the detected X-rays An irradiation dose control method for an X-ray diagnostic apparatus having a generating means,
Presetting X-ray irradiation conditions for the X-ray generation unit;
Calculating an irradiation dose in the subject based on the set X-ray irradiation conditions;
Comparing the calculated irradiation dose with a preset allowable irradiation dose;
Updating the X-ray irradiation conditions based on the comparison result;
An irradiation dose control method comprising the step of irradiating the subject with X-rays based on the updated X-ray irradiation conditions.

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