JP2019145435A - X-ray diagnostic device - Google Patents

Abstract

To reduce a rise time for X-ray output without loading and overloading a filament during a period of no X-ray irradiation.SOLUTION: In an embodiment, an X-ray diagnostic device includes an X-ray tube, a filament heating unit, and a filament control unit. The X-ray tube has a first filament and a second filament, and generates X-rays from a focal point where a plurality of electron beams converge according to filament currents flowing individually through the first filament and the second filament. The filament heating unit simultaneously heats the first filament and the second filament by applying a filament current corresponding to a tube current for the first filament and the second filament. The filament control unit controls the filament heating unit such that the X-ray output maintains a desired target value.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an X-ray diagnostic apparatus.

  Generally, an X-ray diagnostic apparatus heats a filament of an X-ray tube by applying a tube voltage to the X-ray tube, and generates X-rays by applying thermoelectrons generated from the heated filament to a target. . At this time, it usually takes about 1 to 2 seconds (rise time) from the start of heating the filament until the filament temperature is stabilized (that is, until the X-ray output is stabilized at a desired output value). Take it.

  The X-ray diagnostic apparatus may have, for example, a preheating function or a rapid heating function from the viewpoint of shortening this type of rise time. The preheating function is a function of heating the filament to such an extent that thermoelectrons are not generated in a period in which X-ray irradiation is not performed. The rapid heating function is a function of rapidly heating the filament immediately after the start of heating of the filament.

JP-A-64-82496

  However, the X-ray diagnostic apparatus as described above is usually not particularly problematic, but according to the study of the present inventor, there is a possibility that the load on a certain filament may be increased by using the preheating function or the rapid heating function. is there. For example, when the preheating function is used, since the continuous heating time for a certain filament becomes longer than usual, the load on the filament may increase. For example, when using the rapid heating function, an excessive load may be applied to a certain filament.

  An object of the present invention is to provide an X-ray diagnostic apparatus that can shorten the rise time relating to the X-ray output without imposing an excessive load on the filament and an excessive load on the filament during a period when X-rays are not irradiated.

  According to the embodiment, the X-ray diagnostic apparatus includes an X-ray tube, a filament heating unit, and a filament control unit. The X-ray tube has a first filament and a second filament, and generates X-rays from a focal point where a plurality of electron beams according to filament currents individually flowing in the first filament and the second filament converge. . The filament heating unit heats the first filament and the second filament simultaneously by applying a filament current corresponding to the tube current to the first filament and the second filament. The filament control unit controls the filament heating unit so that the X-ray output maintains a desired target value.

It is a block diagram which shows an example of a structure of the X-ray diagnostic apparatus which concerns on 1st Embodiment. It is a block diagram which shows an example of a structure of the X-ray high voltage apparatus and its periphery in the same embodiment. It is a figure which illustrates a part of structure of the X-ray tube in the same embodiment. It is a figure which illustrates the two filaments with the substantially same focus size with which the cathode of the X-ray tube in the embodiment was equipped, and the focus of a target. It is a flowchart for demonstrating an example of operation | movement of the X-ray diagnostic apparatus in the embodiment. It is a timing chart which shows an example of the control method of the some filament in the embodiment. It is a flowchart for demonstrating another example of operation | movement of the X-ray diagnostic apparatus in the embodiment. It is a timing chart which shows another example of the control method of the several filament in the embodiment. It is a figure which illustrates two filaments with which the focus sizes with which the X-ray tube which the X-ray diagnostic apparatus which concerns on 2nd embodiment has was equipped with different focus sizes, and the focus of a target. It is a figure which illustrates three filaments with which the cathode of the X-ray tube which the X-ray diagnostic apparatus which concerns on 3rd Embodiment has, and the focus of a target. It is a figure which illustrates two filaments with which the focus size provided in the cathode of the X-ray tube which the X-ray diagnostic apparatus concerning a 4th embodiment can change, and the focus of a target.

  Hereinafter, each embodiment will be described with reference to the drawings. In each embodiment, the same or similar elements as the already described elements are denoted by the same or similar reference numerals, and redundant description is omitted, and unexplained elements are mainly described.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration example of an X-ray diagnostic apparatus 1 according to the first embodiment. The X-ray diagnostic apparatus 1 includes an X-ray high voltage apparatus 2, an X-ray source apparatus 3, an X-ray detector 4, a support frame 5, a couch having a top plate 6, an image generation circuit 7, and a communication interface circuit 8. An input interface circuit 9, a control circuit 10, a memory circuit 11, and a display circuit 12. The X-ray source device 3 includes an X-ray tube 3a and an X-ray movable diaphragm 3b. Note that the X-ray diagnostic apparatus 1 corresponds to, for example, an X-ray fluoroscopic diagnostic apparatus used in a gastrointestinal contrast examination. In addition, the X-ray diagnostic apparatus 1 may be, for example, a circulatory X-ray fluoroscopic diagnostic apparatus used in angiographic examination or the like.

  The X-ray high voltage apparatus 2 generates a tube current and a tube voltage to be applied to the X-ray tube 3a. Specifically, as illustrated in FIG. 2, the X-ray high voltage apparatus 2 includes a high voltage generation circuit 21, a filament heating circuit 22, and an X-ray control circuit 23. Note that the X-ray high voltage apparatus 2 corresponds to, for example, an X-ray high voltage apparatus using an inverter control system.

  Under the control of the X-ray control circuit 23, the high voltage generation circuit 21 applies a tube current and a tube current suitable for X-ray imaging and X-ray fluoroscopy to the X-ray tube 3a. The high voltage generation circuit 21 further includes a tube voltage detection circuit 21a and a tube current detection circuit 21b.

  The tube voltage detection circuit 21a detects the value of the tube voltage applied to the X-ray tube 3a. The tube voltage detection circuit 21a outputs the detected tube voltage value to the X-ray control circuit 23 as a tube voltage detection value. The tube voltage detection circuit 21a corresponds to, for example, a voltage sensor.

  The tube current detection circuit 21b detects the value of the tube current applied to the X-ray tube 3a. The tube current detection circuit 21b outputs the detected tube current value to the X-ray control circuit 23 as a tube current detection value. The tube current detection circuit 21b corresponds to, for example, a current sensor.

  The filament heating circuit 22 heats a plurality of filaments simultaneously by applying a filament current corresponding to the tube current to the plurality of filaments of the X-ray tube 3a under the control of the X-ray control circuit 23. . The filament heating circuit 22 corresponds to, for example, a filament heating circuit using a high frequency heating method. “Applying current to the filament” is synonymous with “heating the filament”.

  The filament heating circuit 22 may be configured to be able to detect the filament currents applied to the plurality of filaments. Further, the filament heating circuit 22 may be added with a configuration capable of detecting the temperature of each of the plurality of filaments or the sum of the temperatures of the plurality of filaments. Further, the filament heating circuit 22 may be included in the high voltage generation circuit 21.

  The X-ray control circuit 23 is a processor that controls the high voltage generation circuit 21 and the filament heating circuit 22. The X-ray control circuit 23 receives an X-ray condition from the input interface circuit 9. The X-ray control circuit 23 controls the high voltage generation circuit 21 based on the X-ray condition.

  Further, the X-ray control circuit 23 executes a function for controlling the value of the filament current applied to the plurality of filaments in accordance with an operator instruction stored in the memory. The function includes, for example, a filament control function 23a.

  The filament control function 23a is a filament heating circuit 22 that controls the filament current applied to the plurality of filaments so that the X-ray output contributed by the plurality of filaments maintains a desired target value (X-ray output target value). To control. Specifically, for example, the filament control function 23a controls the filament heating circuit 22 so as to gradually lower the filament current applied to a certain filament when the X-ray output reaches a desired target value. . For example, the filament control function 23a is triggered by the fact that the X-ray output has reached a desired target value, and the filament heating circuit 22 maintains the filament current applied to the plurality of filaments at the current value at that time. To control.

  The filament control function 23a may control the filament heating circuit 22 so as to select an optimum filament based on information on a necessary heating amount for each filament stored in advance in the storage circuit 11 or the like. . As a selection method, for example, a table in which the target value of the tube current, the heating amount and the filament current value of each filament corresponding to the target value of the tube current, and the identifier of each filament are associated is stored in the storage circuit 11 in advance. It is good also as a method to do. In this case, each filament can be optimally selected by reading the identifier (and filament current value) of each filament from the table based on the target value of the tube current. For each selected filament, the target value of the tube current can be achieved by controlling the filament heating circuit 22 based on the filament current value.

  Alternatively, the filament control function 23a may control the filament heating circuit 22 so as to optimally allocate the heating amount for each filament. As an allocation method, for example, a table in which a target value of the tube current, a heating amount of each filament corresponding to the target value of the tube current, and a filament current value are associated with each other may be stored in the storage circuit 11 in advance. In this case, the heating amount of each filament can be optimally allocated by reading the (heating amount and) filament current value of each filament from the table based on the target value of the tube current.

  Since the X-ray output is determined based on the X-ray condition, the values of the tube voltage, the tube current, and the filament current are related to each other. That is, if the relationship is known, for example, a tube current detection value (tube current detection value) may be used as the X-ray output, and a desired target value (X-ray output target value) may be set, for example. You may use the value of the tube current in the X-ray conditions. When the filament temperature can be measured, the X-ray output may be the sum of the temperatures of the plurality of filaments, and the X-ray output target value may be a desired temperature for a certain filament.

  The X-ray tube 3 a generates X-rays based on the tube current and tube voltage applied from the X-ray high voltage device 2. X-rays generated by the X-ray tube 3a are applied to the subject P. Specifically, the X-ray tube 3a has a first filament and a second filament, and the X-ray tube 3a has a focal point where a plurality of electron beams according to filament currents flowing individually in the first filament and the second filament converge. Generate a line. That is, the focal points of the plurality of filaments are in positions where they overlap each other.

  The X-ray tube 3a has, for example, two filaments (a first filament and a second filament) having substantially the same focal spot size as a cathode. The term “substantially identical” may be read as a term that is substantially equal. The X-ray tube 3a corresponds to, for example, a rotary anode type X-ray tube. The X-ray tube 3a may be, for example, a fixed anode type X-ray tube.

  FIG. 3 shows a part of the configuration of the X-ray tube 3a. In the X-ray tube 3 a, an anode voltage is applied to the anode having the target 32, a filament voltage is applied to the filament of the cathode 31, and a grid voltage is applied to the grid of the cathode 31. As a result, a tube voltage is applied between the filament and the anode. The X-ray tube 3a emits thermal electrons from the filament in the cathode 31 by the applied tube voltage. The emitted thermoelectrons (electron beam) are converted into X-rays by the energy when colliding with the anode target 32. The electron beam from the filament to the target corresponds to the tube current. The value of the tube current is controlled by the filament current. The target 32 corresponds to a rotary anode target that can rotate around the rotation axis RA.

  In FIG. 4, filaments 31a and 31b (first filament and second filament) having substantially the same focal size provided in the cathode 31 of the X-ray tube 3a and the focal point 32a of the target 32 are illustrated. Filament currents are simultaneously applied to the filaments 31 a and 31 b provided in the cathode 31 by the filament heating circuit 22. The filaments 31a and 31b emit thermoelectrons when a filament current is applied and heat is generated. Thermoelectrons (a plurality of electron beams) emitted from the filaments 31a and 31b collide with the focal point 32a of the target 32, respectively. Some of the thermoelectrons that have collided with the focal point 32a are converted into X-rays by the energy during the collision. That is, X-rays are generated from the focal point 32a where a plurality of electron beams converge.

  The positions of the filaments 31a and 31b are not limited to the positions illustrated in FIG. 4 and may be any positions where the thermoelectrons from the filaments 31a and 31b can converge at the focal point 32a. In addition, since the focus sizes of the filaments 31a and 31b are substantially the same, even when a plurality of filaments are used, the focus size when a single filament is used can be maintained.

  The X-ray movable diaphragm 3b limits the irradiation field of X-rays generated by the X-ray tube 3a. The X-ray movable diaphragm 3b can irradiate only the imaging region (or imaging range) of the subject P desired by the operator by limiting the X-ray irradiation field. That is, the X-ray movable diaphragm 3b can prevent unnecessary exposure to a part (or range) different from the imaging part (or imaging range). In addition, the X-ray movable diaphragm 3b can reduce scattered X-rays and remove out-of-focus X-rays.

  The X-ray detector 4 detects X-rays generated from the X-ray tube 3a and transmitted through the subject P. The X-ray detector 4 includes, for example, a flat panel detector (FPD) that can detect X-rays. The FPD has a plurality of semiconductor detection elements. Semiconductor detection elements include indirect conversion types and direct conversion types. The indirect conversion type is a format in which incident X-rays are converted into light by a scintillator such as a phosphor, and the converted light is converted into an electrical signal. The direct conversion type is a type in which incident X-rays are directly converted into electrical signals. An image intensifier may be used as the X-ray detector 4. In this specification, a range in which the X-ray detector 4 can detect X-rays is referred to as an “X-ray detection region”.

  Electrical signals generated by a plurality of semiconductor detection elements as X-rays are incident are output to an analog-to-digital converter (A / D converter) (not shown). The A / D converter converts an electrical signal into digital data. The A / D converter outputs digital data to the image generation circuit 7.

  The support frame 5 movably supports the X-ray source device 3 and the X-ray detector 4 that are arranged to face each other. Specifically, the support frame 5 corresponds to an overtube frame in which the X-ray source device 3 is installed above the surface of the top plate 6. The support frame 5 may be an under tube type frame in which the X-ray source device 3 is installed below the surface of the top plate 6. Further, the support frame 5 may have a structure with a C arm and an Ω arm. Further, the support frame 5 may have a structure including two arms (for example, robot arms) that independently support the X-ray source device 3 and the X-ray detector 4.

  A couch (not shown) has a top 6 (also referred to as a prone table) on which the subject P is placed. A subject P is placed on the top 6.

  A drive device (not shown) drives the support frame 5 and the bed, for example, under the control of the control circuit 10. During X-ray fluoroscopy and X-ray imaging, the subject P placed on the top 6 is disposed between the X-ray source device 3 and the X-ray detector 4. Further, the driving device drives the X-ray movable diaphragm 3b under the control of the control circuit 10, for example. Note that the driving device may rotate the X-ray detector 4 with respect to the X-ray source device 3 under the control of the control circuit 10.

  The image generation circuit 7 generates an X-ray image based on the digital data output from the X-ray detector 4 via the A / D converter. The image generation circuit 7 outputs the generated X-ray image to the storage circuit 11 and an external storage device (not shown).

  The communication interface circuit 8 is, for example, a circuit related to a network and an external storage device (not shown). An X-ray image obtained by the X-ray diagnostic apparatus 1 can be transferred to another apparatus via the communication interface circuit 8 and the network. Hereinafter, when information is exchanged via the communication interface circuit 8, the description “through the communication interface circuit 8” is omitted.

  The input interface circuit 9 includes an X-ray imaging condition desired by the operator, an X-ray irradiation condition such as an X-ray fluoroscopic condition, a fluoroscopic / imaging position, an irradiation field, and a region of interest in the X-ray image (region of interest). : ROI) or the like is input according to the operator's instruction. Specifically, the input interface circuit 9 captures various instructions, commands, information, selections, and settings from the operator into the X-ray diagnostic apparatus 1.

  The input interface circuit 9 includes a joystick for setting a region of interest, a trackball, a switch button, a mouse, a keyboard, a touch pad for performing an input operation by touching an operation surface, a display screen, and a touch pad. This is realized by a touch panel display, a foot switch for photographing, a microphone for voice recognition, and the like. The input interface circuit 9 is connected to the control circuit 10 and converts the input operation received from the operator into an electrical signal and outputs it to the control circuit 10.

  In the present specification, the input interface circuit 9 is not limited to one having physical operation components such as a mouse and a keyboard. For example, an example of the input interface circuit 9 includes an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the apparatus and outputs the electric signal to the control circuit 10. It is.

  The control circuit 10 is, for example, a processor that controls each circuit and driving device in the X-ray diagnostic apparatus 1. The control circuit 10 temporarily stores information such as an operator instruction input from the input interface circuit 9 in a memory (not shown). The control circuit 10 controls the X-ray high-voltage device 2, the X-ray movable diaphragm 3 b, the driving device, and the like in order to execute X-ray imaging and X-ray fluoroscopy in accordance with an operator instruction stored in the memory. . Further, the control circuit 10 controls the X-ray image generation processing in the image generation circuit 7 and the like.

  The storage circuit 11 includes a memory for recording electrical information such as an HDD (Hard Disk Drive), and peripheral circuits such as a memory controller and a memory interface associated with the memory. The memory is not limited to HDD, but SSD (solid state drive), magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD, DVD, Blu-ray (registered trademark), etc.), semiconductor memory, etc. Can be used as appropriate.

  The storage circuit 11 includes various X-ray images generated by the image generation circuit 7, a system control program of the X-ray diagnostic apparatus 1, a diagnostic protocol executed by the control circuit 10, and an operator sent from the input interface circuit 9. , Various data groups such as imaging conditions related to X-ray imaging and fluoroscopic conditions related to X-ray fluoroscopy, error information, and various data transmitted via the network are stored. The storage circuit 11 may store a table in which the target value of the current, the heating amount and the filament current value of each filament corresponding to the target value of the tube current, and the identifier of each filament are associated.

  The display circuit 12 includes a display that displays a medical image, an internal circuit that supplies a display signal to the display, and peripheral circuits such as a connector and a cable that connect the display and the internal circuit.

  The display displays the X-ray image generated by the image generation circuit 7. The display may be a display window for displaying an X-ray image on the entire surface of the display, a part of the display may be a display window, or both of them may be switched. The display may display an input screen related to input of fluoroscopy / imaging position, X-ray irradiation conditions, and the like.

(First operation example)
Next, the operation (first operation example) of the X-ray diagnostic apparatus 1 configured as described above will be described using the flowchart of FIG. 5 and the timing chart of FIG. The following description mainly describes control of the value of the filament current applied to a plurality of filaments by the filament control function 23a. 6A shows a waveform indicating that the X-ray irradiation switch is turned on, FIG. 6B shows a solid line showing an X-ray output waveform, FIG. 6C shows a current value waveform of the first filament, and FIG. (D) is a waveform of the current value of the second filament.

  First, the subject P is placed on the couch top 6. The X-ray diagnostic apparatus 1 selects an examination type and examination name set in advance by an operation of the operator, and sets an imaging condition (X-ray condition) associated with the selected examination type and examination name. Thereafter, the X-ray diagnostic apparatus 1 starts X-ray fluoroscopy by turning on the irradiation switch of the input interface circuit 9 by the operator's operation, and starts step ST11.

  In step ST11, the filament heating circuit 22 heats the plurality of filaments simultaneously by applying a filament current corresponding to the tube current to the plurality of filaments under the control of the X-ray control circuit 23.

Specifically, the filament heating circuit 22 is subjected to from the time t ₀ of time t _1, the applied filament current corresponding to the tube current to the filament 31a, 31b (the first filament and the second filament) By heating the first filament and the second filament at the same time. At the same time, the tube current detection circuit 21b always detects the value of the tube current applied to the X-ray tube 3a, and always outputs the detected tube current value to the X-ray control circuit 23 as a tube current detection value. .

  In step ST12 and step ST13, the filament control function 23a generates the filament current via the filament heating circuit 22 so that the X-ray output contributed by the first filament and the second filament maintains a desired target value. Control. In this operation example, the filament control function 23a performs control to gradually decrease the filament current applied to the second filament when the X-ray output reaches a desired target value.

  In step ST12, the filament control function 23a determines whether or not the X-ray output substantially reaches a desired target value (X-ray output target value). If the X-ray output has reached the X-ray output target value, the process proceeds to step ST13, and if not, the process returns to step ST11.

  Specifically, the filament control function 23a uses the tube current detection value as the X-ray output and uses the tube current target value as the X-ray output target value. The filament control function 23a determines whether or not the tube current detection value received from the tube current detection circuit 21b has substantially reached the tube current target value.

  In step ST13, the filament heating circuit 22 decreases the filament current applied to the second filament while maintaining the current X-ray output under the control of the filament control function 23a.

Specifically, the filament control function 23a performs control to continuously apply the filament current corresponding to the tube current of the tube current target value for the first filament, and the tube current detection value for the second filament is the tube current target value. In order to maintain the above, the filament current to be applied is controlled so as to gradually decrease with time. Filament heating circuit 22, subjected to from the time t ₁ of time t _2, the continuously applied to filament current according to the tube current of the tube current target value for the first filament, the tube current detected value for the second filament tube In order to maintain the current target value, the applied filament current is gradually lowered with time.

In addition, the dotted line of FIG.6 (b) is a waveform of the X-ray output at the time of utilizing only a 1st filament. The waveform at time t _2, the X-ray output reaches the X-ray output target value. Therefore, when the first filament and the second filament are used as in the present embodiment, the time required to reach the X-ray output target value is shortened by the time t _r (= t ₂ −t ₁ ). can do.

(Second operation example)
In the first operation example, the first filament and the second filament were heated at the same time, and then the first filament was heated to the target value, and the second filament was controlled to be used as an auxiliary. In the second operation example, the first filament and the second filament are heated at the same time, and then the tube current value when the X-ray output target value is reached is maintained, respectively. Controls the filament current supplied to the filament.

  A second operation example will be described with reference to the flowchart of FIG. 7 and the timing chart of FIG. The following description mainly describes control of the value of the filament current applied to a plurality of filaments by the filament control function 23a. 8A is a waveform indicating that the X-ray irradiation switch is ON, the solid line in FIG. 8B is the waveform of the X-ray output, FIG. 8C is the waveform of the current value of the first filament, and FIG. (D) is a waveform of the current value of the second filament. In addition, preparation before starting step ST11 and step ST11 are the same as those in the first operation example, and thus description thereof is omitted.

  In step ST12 and step ST21, the filament control function 23a generates a filament current via the filament heating circuit 22 so that the X-ray output contributed by the first filament and the second filament maintains a desired target value. Control. In this operation example, the filament control function 23a uses the current value at that time as the filament current applied to the first filament and the second filament when the X-ray output reaches a desired target value. Control to maintain.

  In step ST12, the filament control function 23a determines whether or not the X-ray output substantially reaches a desired target value (X-ray output target value). If the X-ray output has reached the X-ray output target value, the process proceeds to step ST21, and if not, the process returns to step ST11.

  Specifically, the filament control function 23a uses the tube current detection value as the X-ray output and uses the tube current target value as the X-ray output target value. The filament control function 23a determines whether or not the tube current detection value received from the tube current detection circuit 21b has substantially reached the tube current target value.

  In step ST21, the filament heating circuit 22 maintains the currents applied to the first filament and the second filament as they are under the control of the filament control function 23a.

Specifically, the filament control function 23a performs control to continuously apply the filament current corresponding to the tube current detection value for the first filament and the second filament. The filament heating circuit 22 continues to apply a filament current corresponding to the tube current detection value for the first filament and the second filament from time t ₁ to time t ₂ .

In addition, the dotted line of FIG.8 (b) is a waveform of the X-ray output at the time of utilizing only a 1st filament. The waveform at time t _2, the X-ray output reaches the X-ray output target value. Therefore, when the first filament and the second filament are used as in the present embodiment, the time required to reach the X-ray output target value is shortened by the time t _r (= t ₂ −t ₁ ). can do.

  As described above, according to the first embodiment, the X-ray diagnostic apparatus emits X-rays from the focal point where a plurality of electron beams according to the filament currents individually flowing in the first filament and the second filament converge. A generating X-ray tube is provided. The X-ray diagnostic apparatus heats the first filament and the second filament simultaneously by applying a filament current to the first filament and the second filament. Further, the X-ray diagnostic apparatus controls the filament heating unit so that the X-ray output maintains a desired target value. Therefore, since the X-ray diagnostic apparatus can generate thermoelectrons necessary for X-ray output using a plurality of filaments at the same time, the load on the filament and the excessive load on the filament during the period when the X-ray is not irradiated are generated. Without taking up, the rise time concerning the X-ray output can be shortened.

  Further, according to the first embodiment, the X-ray diagnostic apparatus uses the filament so as to gradually decrease the filament current applied to the second filament when the X-ray output reaches a desired target value. Control the heating section. Therefore, since the X-ray diagnostic apparatus can perform heating control as usual for one filament and can use the other filament as an auxiliary, the load on the filament during the X-ray irradiation period is minimized. It can be kept in.

  Further, according to the first embodiment, the X-ray diagnostic apparatus uses the filament current to be applied to the first filament and the second filament triggered by the X-ray output reaching a desired target value. The filament heating unit is controlled to maintain the current value at that time. Therefore, since the X-ray diagnostic apparatus can apply less current to a plurality of filaments than before, the load on the filament during the X-ray irradiation period can be minimized.

  By shortening the rise time concerning X-ray output, the time until an X-ray image is obtained or the time until X-ray fluoroscopy is started is shortened. Thereby, X-ray imaging or X-ray fluoroscopy can be performed at the timing intended by the operator, and the burden on the subject (physical burden such as breath holding and posture maintenance) can be reduced. In addition, since the examination time can be shortened, the influence of exposure of the operator and the subject can be reduced.

(Second Embodiment)
In the first embodiment, the case where the two filaments provided in the cathode of the X-ray tube have substantially the same focal spot size has been described. In the second embodiment, a case where the focal point sizes of one filament and the other filament are different will be described. Note that “when the focus sizes are different” means that the focus sizes are not substantially the same. The X-ray tube 3a in the second embodiment has two filaments (first filament and second filament) having different focal spot sizes.

  The X-ray tube 3a has, for example, two filaments (first filament and second filament) having different focal spot sizes, and the focal spot size of the first filament is larger than the focal spot size of the second filament. The focal point of the first filament and the focal point of the second filament are in positions overlapping each other.

  FIG. 9 illustrates an example of two filaments with different focal spot sizes provided in the cathode of the X-ray tube and the focal point of the target. A filament current is simultaneously applied to the large filament 31c and the small filament 31d (first filament and second filament) provided in the cathode 31 by the filament heating circuit 22, respectively. The large filament 31c and the small filament 31d emit thermal electrons when a filament current is applied to generate heat. The thermoelectrons emitted from the large filament 31c and the small filament 31d collide with the large focal point 32b and the small focal point 32c of the target 32, respectively. The thermoelectrons that collide with the large focal point 32b and the small focal point 32c are partially converted into X-rays by the energy at the time of the collision.

  Note that the positions of the large filament 31c and the small filament 31d are not limited to the positions illustrated in FIG. 9, but are positions where thermoelectrons from the large filament 31c and the small filament 31d can converge to the large focal point 32b and the small focal point 32c, respectively. Good. The large focal point 32b and the small focal point 32c need only be in positions that overlap each other. Thereby, the focal size when using the large filament 31c and the small filament 31d can be maintained as the focal size of the large filament 31c (the focal size of the large focal point 32b).

  Since the operation of the X-ray diagnostic apparatus 1 in the second embodiment is substantially the same as the first operation example and the second operation example of the first embodiment, the description thereof is omitted.

  As described above, according to the second embodiment, in the X-ray tube of the X-ray diagnostic apparatus, the focal size of the first filament is larger than the focal size of the second filament. Therefore, the X-ray diagnostic apparatus can shorten the rise time related to the X-ray output for the larger one of the two different focus sizes. In addition, the X-ray diagnostic apparatus can obtain substantially the same effect as that of the first embodiment.

(Third embodiment)
In the second embodiment, the case where the rise time for the X-ray output is shortened only for the large focus by using the X-ray tube including the large focus filament and the small focus filament has been described. In the third embodiment, a case will be described in which the X-ray tube of the second embodiment is further provided with a small-focus filament, so that the rise time related to the X-ray output can be shortened even for the small focus.

  The X-ray tube 3a has, for example, a large focal filament and two small focal filaments (first filament, second filament, and third filament). Specifically, the focal size of the first filament is larger than the focal size of the second filament, and the focal size of the second filament is substantially equal to the focal size of the third filament. The focal points of the three filaments are positioned so as to overlap each other.

  FIG. 10 illustrates three filaments provided on the cathode of the X-ray tube and the focus of the target. A filament current is simultaneously applied to the large filament 31c, the small filament 31d, and the small filament 31e (first filament, second filament, and third filament) provided in the cathode 31 by the filament heating circuit 22, respectively. . The large filament 31c, the small filament 31d, and the small filament 31e emit thermal electrons when a filament current is individually applied to generate heat. The thermoelectrons (multiple electron beams) emitted from the large filament 31c, the small filament 31d, and the small filament 31e collide with the large focal point 32b of the target 32, and the thermoelectrons emitted from the small filament 31d and the small filament 31e are , Each collides with a small focal point 32c of the target 32. The thermoelectrons that collide with the large focal point 32b and the small focal point 32c are partially converted into X-rays by the energy at the time of the collision. That is, X-rays are generated from the large focal point 32b and the small focal point 32c where a plurality of electron beams converge.

  Note that the positions of the large filament 31c, the small filament 31d, and the small filament 31e are not limited to the positions illustrated in FIG. 10, and the thermoelectrons from the large filament 31c, the small filament 31d, and the small filament 31e enter the large focal point 32b. Any position where thermoelectrons from the small filament 31d and the small filament 31e can converge at the small focal point 32c may be used. The large focal point 32b and the small focal point 32c need only be in positions that overlap each other.

(First operation example)
The operation (first operation example) of the X-ray diagnostic apparatus 1 in the third embodiment will be described with reference to the flowchart of FIG. 5 and the timing chart of FIG. In the following description, the case where the large focal point 32b is mainly used will be described. When the large focal point 32b is used, the third filament may be controlled in the same manner as the second filament, and thus the description in the drawing is omitted. When the small focal point 32c is used, the first filament is not used, the second filament and the third filament are used, and the same operation as that of the first embodiment may be performed. Is omitted. The preparation before starting step ST11 is the same as that in the first embodiment, and a description thereof will be omitted.

  In step ST11, the filament heating circuit 22 heats the plurality of filaments simultaneously by applying a filament current corresponding to the tube current to the plurality of filaments under the control of the X-ray control circuit 23.

Specifically, the filament heating circuit 22 is subjected to from the time t ₀ of time t _1, the large filament 31c, the small filaments 31d, and small filaments 31e (first filament, the second filament, and the third filament The first filament, the second filament, and the third filament are heated at the same time by applying a filament current corresponding to the tube current. At the same time, the tube current detection circuit 21b always detects the value of the tube current applied to the X-ray tube 3a, and always outputs the detected tube current value to the X-ray control circuit 23 as a tube current detection value. .

  In step ST12 and step ST13, the filament control function 23a is desired to output an X-ray contributed by a plurality of electron beams according to filament currents individually flowing in the first filament, the second filament, and the third filament. The filament current is controlled via the filament heating circuit 22 so as to maintain the target value. In the present operation example, the filament control function 23a performs control to gradually decrease the filament current applied to the second filament and the third filament when the output of the X-ray reaches a desired target value.

  In step ST12, the filament control function 23a determines whether or not the X-ray output substantially reaches a desired target value (X-ray output target value). If the X-ray output has reached the X-ray output target value, the process proceeds to step ST13, and if not, the process returns to step ST11.

  Specifically, the filament control function 23a uses the tube current detection value as the X-ray output and uses the tube current target value as the X-ray output target value. The filament control function 23a determines whether or not the tube current detection value received from the tube current detection circuit 21b has substantially reached the tube current target value.

  In step ST13, the filament heating circuit 22 decreases the filament current applied to the second filament and the third filament while maintaining the current X-ray output under the control of the filament control function 23a.

Specifically, the filament control function 23a performs control to continuously apply the filament current corresponding to the tube current of the tube current target value for the first filament, and the tube current detection value for the second filament and the third filament. In order to maintain the tube current target value, the filament current to be applied is controlled to gradually decrease with time. The filament heating circuit 22 continues to apply a filament current corresponding to the tube current of the tube current target value for the first filament from time t ₁ to time t ₂ , and the tube for the second filament and the third filament. The filament current to be applied is gradually lowered with time so that the current detection value maintains the tube current target value.

(Second operation example)
In the first operation example, when using a large focal point, the first filament, the second filament, and the third filament are heated at the same time, and then the first filament is heated to a target value. Control was performed using the second filament and the third filament as auxiliary. In the second operation example, when using a large focal point, the first filament, the second filament, and the third filament are simultaneously heated, and then the tube current at the time when the X-ray output target value is reached. The filament current supplied to the first filament, the second filament, and the third filament is controlled so as to maintain the respective values.

  A second operation example will be described with reference to the flowchart of FIG. 7 and the timing chart of FIG. In the following description, the case where the large focal point 32b is mainly used will be described. When the large focal point 32b is used, the third filament may be controlled in the same manner as the second filament, and thus the description in the drawing is omitted. When the small focal point 32c is used, the first filament is not used, the second filament and the third filament are used, and the same operation as that of the first embodiment may be performed. Is omitted. In addition, preparation before starting step ST11 and step ST11 are the same as those in the first operation example, and thus description thereof is omitted.

  In step ST12 and step ST21, the filament control function 23a controls the filament current so that the X-ray output contributed by the first filament, the second filament, and the third filament maintains a desired target value. To do. In this operation example, the filament control function 23a uses the filament current applied to the first filament, the second filament, and the third filament as triggered by the X-ray output reaching a desired target value. Control is performed to maintain the current value at that time.

  In step ST12, the filament control function 23a determines whether or not the X-ray output substantially reaches a desired target value (X-ray output target value). If the X-ray output has reached the X-ray output target value, the process proceeds to step ST21, and if not, the process returns to step ST11.

  Specifically, the filament control function 23a uses the tube current detection value as the X-ray output and uses the tube current target value as the X-ray output target value. The filament control function 23a determines whether or not the tube current detection value received from the tube current detection circuit 21b has substantially reached the tube current target value.

  In step ST21, the filament heating circuit 22 maintains the currents applied to the first filament, the second filament, and the third filament as they are under the control of the filament control function 23a.

Specifically, the filament control function 23a performs control to continuously apply the filament current corresponding to the tube current detection value for the first filament, the second filament, and the third filament. The filament heating circuit 22 continues to apply a filament current corresponding to the tube current detection value for the first filament, the second filament, and the third filament from time t ₁ to time t ₂ .

  As described above, according to the third embodiment, the X-ray diagnostic apparatus can obtain the same effects as those of the first embodiment.

  In addition, according to the third embodiment, the X-ray diagnostic apparatus applies the filament current to the first filament, the second filament, and the third filament, whereby the first filament and the second filament are applied. The filament and the third filament are heated simultaneously. Further, the X-ray diagnostic apparatus maintains a desired target value for the X-ray output contributed by a plurality of electron beams according to the filament currents individually flowing through the first filament, the second filament, and the third filament. In addition, the filament current is controlled. Therefore, since the X-ray diagnostic apparatus can generate thermoelectrons necessary for X-ray output using a plurality of filaments at the same time, the load on the filament and the excessive load on the filament during the period when the X-ray is not irradiated are generated. Without taking up, the rise time concerning the X-ray output can be shortened.

  In addition, according to the third embodiment, the X-ray tube included in the X-ray diagnostic apparatus has a first filament whose focal spot size is larger than that of the second filament, and the second filament focal spot size and the second filament focal spot size. The focal size of the 3 filaments is approximately equal. Therefore, the X-ray diagnostic apparatus can shorten the rise time relating to the X-ray output for two different focal spot sizes.

(Fourth embodiment)
In the first to third embodiments, the case where the focal point size of each filament provided in the cathode of the X-ray tube is fixed has been described. In the fourth embodiment, a case will be described in which two filaments are variable focus filaments capable of switching focus sizes. As this type of variable focus filament, for example, a structure for switching electrical connection between one end of the filament and the other end or the middle of the filament can be used. Note that the variable focus filament is not limited to this, and a structure in which a plurality of filaments having different focus sizes are switched may be used.

  The X-ray tube 3a has, for example, two filaments (first filament and second filament) whose focus size can be switched between a large focus and a small focus. In other words, the X-ray tube 3a can switch the focus size of the first filament and the focus size of the second filament to a plurality of focus sizes.

  FIG. 11 exemplifies two filaments that can switch the focus size provided at the cathode of the X-ray tube to a large focus and a small focus, and the focus of the target. Filament currents are simultaneously applied to the variable focus filaments 31 f and 31 g (first filament and second filament) provided in the cathode 31 by the filament heating circuit 22. The variable focus filaments 31f and 31g emit thermoelectrons when a filament current is applied and heat is generated.

  As illustrated in FIG. 11A, when the variable focal filaments 31f and 31g have a large focal point, the thermoelectrons emitted from the variable focal filaments 31f and 31g collide with the large focal point 32b of the target 32, respectively. The thermoelectrons that collide with the large focal point 32b are partially converted into X-rays by the energy at the time of the collision.

  As illustrated in FIG. 11B, when the variable focus filaments 31f and 31g have a small focus, the thermoelectrons emitted from the variable focus filaments 31f and 31g collide with the small focus 32c of the target 32, respectively. The thermoelectrons that collide with the small focal point 32c are partially converted into X-rays by the energy at the time of the collision.

  Note that the positions of the variable focal filaments 31f and 31g are not limited to the positions illustrated in FIG. 11, and may be any positions where the thermoelectrons from the variable focal filaments 31f and 31g can converge to the large focal point 32b or the small focal point 32c.

  Since the operation of the X-ray diagnostic apparatus 1 in the fourth embodiment is substantially the same as the first operation example and the second operation example of the first embodiment, description thereof is omitted.

  As described above, according to the fourth embodiment, the X-ray diagnostic apparatus can obtain the same effects as those of the first embodiment.

  Further, according to the fourth embodiment, the focal size of the first filament and the focal size of the second filament are variable focal filaments capable of switching the focal size. Therefore, the X-ray diagnostic apparatus can shorten the rise time relating to the X-ray output for two different focal spot sizes.

  The term “processor” used in the above description is, for example, a CPU, a GPU (Graphics Processing Unit), an application-specific integrated circuit (ASIC), a programmable logic device (for example, a simple programmable logic device (for example, It means circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA).

  The processor implements various functions by reading and executing a program stored in the storage circuit. Instead of storing the program in the storage circuit, the program may be directly incorporated in the processor circuit. In this case, the processor implements various functions by reading and executing a program incorporated in the circuit.

  Each processor of the present embodiment is not limited to being configured as a single circuit for each processor, but is configured as a single processor by combining a plurality of independent circuits so as to realize various functions thereof. Also good. Furthermore, a plurality of components may be integrated into one processor to realize the function.

  The filament heating circuit and the filament control circuit in the present embodiment are examples of the filament heating unit and the filament control unit in the claims.

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

  DESCRIPTION OF SYMBOLS 1 ... X-ray diagnostic apparatus, 2 ... X-ray high voltage apparatus, 3 ... X-ray source apparatus, 3a ... X-ray tube, 3b ... X-ray movable diaphragm, 4 ... X-ray detector, 5 ... Support frame, 6 ... Sky Reference numeral 7: Image generation circuit, 8: Communication interface circuit, 9: Input interface circuit, 10: Control circuit, 11: Storage circuit, 12: Display circuit, 21: High voltage generation circuit, 21a: Tube voltage detection circuit, 21b ... Tube current detection circuit, 22 ... Filament heating circuit, 23 ... X-ray control circuit, 23a ... Filament control function, 31 ... Cathode, 31a, 31b ... Filament, 31c ... Large filament, 31d, 31e ... Small filament, 31f, 31g ... variable focus filament, 32 ... target, 32a ... focus, 32b ... large focus, 32c ... small focus, RA ... rotation axis.

Claims (8)

An X-ray tube having a first filament and a second filament, and generating X-rays from a focal point where a plurality of electron beams according to filament currents individually flowing in the first filament and the second filament converge When,
A filament heating unit that simultaneously heats the first filament and the second filament by applying the filament current to the first filament and the second filament;
An X-ray diagnostic apparatus comprising: a filament control unit that controls the filament heating unit so that the output of the X-ray maintains a desired target value. The filament control unit controls the filament heating unit to gradually decrease a filament current applied to the second filament when the output of the X-ray reaches the desired target value. The X-ray diagnostic apparatus according to 1. The filament control unit maintains the filament current applied to the first filament and the second filament at the current value at that time when the output of the X-ray reaches the desired target value. The X-ray diagnostic apparatus according to claim 1, wherein the filament heating unit is controlled to do so.   The X-ray diagnostic apparatus according to any one of claims 1 to 3, wherein the X-ray tube has a focal size of the first filament and a focal size of the second filament substantially equal to each other.   The X-ray diagnostic apparatus according to any one of claims 1 to 3, wherein the X-ray tube has a focal point size of the first filament larger than a focal point size of the second filament. The first filament and the second filament are variable focus filaments capable of switching focus sizes, respectively.
The X-ray diagnostic apparatus as described in any one of Claims 1 thru | or 3. The X-ray tube further includes a third filament,
The filament heating unit applies the filament current to the first filament, the second filament, and the third filament, so that the first filament, the second filament, and the first filament are applied. 3 filaments are heated simultaneously,
The filament control unit is configured to output the X-rays to which a plurality of electron beams according to the filament currents individually flowing in the first filament, the second filament, and the third filament contribute, to the desired value. The X-ray diagnostic apparatus according to any one of claims 1 to 3, wherein the filament heating unit is controlled so as to maintain a target value.   In the X-ray tube, the focal size of the first filament is larger than the focal size of the second filament, and the focal size of the second filament is substantially equal to the focal size of the third filament. Item 8. The X-ray diagnostic apparatus according to Item 7.

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