JP2006014781A - Radiation tomograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the improvement of efficiency of a work by an operator. <P>SOLUTION: A temperature transition calculation part 81 calculates the temperature transition of an X-ray tube 20 and a display device 32 displays the temperature transition of the X-ray tube 20 calculated by the temperature transition calculation part 81. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation tomography apparatus, and in particular, radiation that generates an image of a tomographic plane of a subject based on projection data obtained by detecting radiation that is irradiated on the subject from a radiation generation means and passes through the subject. The present invention relates to a tomography apparatus.

  As a radiation tomography apparatus, an X-ray CT (Computed Tomography) apparatus that generates an image of a tomographic plane of a subject using X-rays that are radiation is known. X-ray CT apparatuses are used in a wide range of applications such as medical applications and industrial applications.

  The X-ray CT apparatus irradiates a subject with X-rays using an X-ray tube. Then, X-rays that pass through the subject are detected by an X-ray detector, and projection data is generated. The X-ray CT apparatus rotates an X-ray tube and an X-ray detector about the slice thickness direction of the subject, emits X-rays from the view direction around the subject, and projects corresponding to each view direction Generate data. Based on the projection data from each view direction, an image of the tomographic plane of the subject is reconstructed and generated.

In the above X-ray CT apparatus, the X-ray tube generates high heat when it is irradiated with X-rays, and failure may occur due to the high heat. For this reason, conventionally, the temperature of the X-ray tube under the set scan conditions is calculated, and if the calculated result exceeds the reference temperature range of the X-ray tube, an instruction to wait for the scan is shown to the operator (for example, , See Patent Document 1).
Japanese Patent Laid-Open No. 10-335092

  However, when the operator receives an instruction to wait for scanning, the state of the X-ray tube according to the scanning condition is not clearly shown, so the operator has no judgment criteria and it is difficult to make the work efficient. Met.

  Accordingly, an object of the present invention is to provide a radiation tomography apparatus that allows an operator to easily perform work efficiently.

  In order to achieve the above object, the radiation tomography apparatus of the present invention provides a tomographic plane of the subject based on projection data obtained by detecting radiation that is irradiated onto the subject from radiation generating means and passes through the subject. A radiation tomography apparatus that generates an image of the above, and includes a calculation unit that calculates a temperature transition of the radiation generation unit, and a display unit that displays the temperature transition of the radiation generation unit calculated by the calculation unit.

  According to the radiation tomography apparatus of the present invention, the calculation unit calculates the temperature transition of the radiation generation unit, and the display unit displays the temperature transition of the radiation generation unit calculated by the calculation unit.

  According to the present invention, it is possible to provide a radiation tomography apparatus in which an operator can easily perform work efficiently.

<Embodiment 1>
Embodiment 1 according to the present invention will be described below.

  FIG. 1 is a block diagram showing an overall configuration of an X-ray CT apparatus 1 as a radiation tomography apparatus according to Embodiment 1 of the present invention, and FIG. 2 shows an X-ray CT apparatus 1 according to an embodiment of the present invention. It is a block diagram which shows the principal part.

  As shown in FIG. 1, the X-ray CT apparatus 1 of this embodiment includes a scanning gantry 2, an operation console 3, and an imaging table 4.

  The scanning gantry 2 includes an X-ray tube 20, an X-ray tube temperature detection unit 20a, an X-ray tube moving unit 21, a collimator 22, an X-ray detector 23, a data collection unit 24, an X-ray controller 25, a collimator controller 26, and a rotation unit. 27 and a rotation controller 28. Here, the X-ray tube 20 and the X-ray detector 23 are disposed to face each other with the bore 29 interposed therebetween.

  The X-ray tube 20 is, for example, a rotary anode type and irradiates X-rays. As shown in FIG. 2, the X-ray tube 20 irradiates X-rays having a predetermined intensity to the imaging region of the subject 6 via the collimator 22 based on a control signal CTL 251 from the X-ray controller 25. In addition, the reference temperature range of the X-ray tube 20 is determined in advance so that the X-ray tube 20 is not damaged by heat generated by the X-ray irradiation.

  The X-ray tube temperature detection unit 20 a includes a temperature sensor and detects the temperature of the X-ray tube 20. Then, the X-ray tube temperature detection unit 20 a outputs the temperature detection data D <b> 1 of the X-ray tube 20 to the central processing unit 30.

  As shown in FIG. 2, the X-ray tube moving unit 21 places the radiation center of the X-ray tube 20 on the imaging table 4 in the bore 29 in the scanning gantry 2 based on the control signal CTL 252 from the X-ray controller 25. The object 6 to be placed is moved in the slice thickness direction z.

  As shown in FIGS. 1 and 2, the collimator 22 is disposed between the X-ray tube 20 and the X-ray detector 23. For example, as shown in FIG. 2, the collimator 22 is composed of two plates each provided in the channel direction x and the slice thickness direction z. Based on the control signal CTL 261 from the collimator controller 26, the collimator 22 moves the two plates provided in each direction independently, and blocks the X-rays emitted from the X-ray tube 20 in each direction. It is molded into a cone and the X-ray irradiation range is adjusted.

  The X-ray detector 23 is rotated together with the X-ray tube 20 by the rotation unit 27 around the slice thickness direction z, detects X-rays transmitted through the subject for each of a plurality of view directions around the subject, and is used as projection data. Is generated. As shown in FIG. 2, the X-ray detector 23 has an X-ray detection module 23A, and a plurality of X-ray detection modules 23A are arranged along the channel direction x and the slice thickness direction z. Has been. The X-ray detectors 23 are arranged such that, for example, J X-ray detection modules 23A are arranged in J in the channel direction x and I in the slice thickness direction z. That is, in the X-ray detector 23, the detection elements 23 a are arrayed in a channel direction x along the rotation direction by the rotation unit 27 and a slice thickness direction z that is a direction substantially perpendicular to the rotation direction by the rotation unit 27. Are two-dimensionally arranged.

  FIG. 3 is a configuration diagram showing the X-ray detection module 23 </ b> A constituting the X-ray detector 23. As shown in FIG. 3, in the X-ray detection module 23A, detection elements 23a for detecting X-rays are arranged in an array in the channel direction x and the slice thickness direction z. The plurality of detection elements 23a arranged two-dimensionally forms an X-ray incident surface curved in a cylindrical concave shape as a whole. Here, in the X-ray detection module 23A, for example, i detection elements 23a are arranged in the channel direction x, and j detection elements 23a are arranged in the slice thickness direction z.

  The detection element 23a includes, for example, a scintillator (not shown) that converts detected X-rays into light, and a photodiode (not shown) that converts light converted by the scintillator into charges. The X-ray detector 23 includes: It is configured as a solid state detector. The detection element 23a is not limited to this. For example, the detection element 23a is a semiconductor detection element using cadmium tellurium (CdTe) or the like, or an ionization chamber type detection element 23a using xenon (Xe) gas. Good.

  4 and 5 are diagrams showing the interrelationship among the X-ray tube 20, the collimator 22, and the X-ray detector 23. FIG. 4A is a diagram illustrating a state in which the slice thickness direction z is a line of sight, and FIG. 4B is a diagram illustrating a state in which the channel direction x is a line of sight. FIG. 5 is a diagram illustrating a state in which the subject 6 is imaged in a state where the line of sight is the channel direction x as in FIG. 4B.

  As shown in FIGS. 4A and 4B, the X-rays emitted from the X-ray tube 20 are formed into a cone shape by the collimator 22 and irradiated to the X-ray detector 23. When imaging the subject 6, the subject 6 is placed on the imaging table 4, and the placed subject 6 is carried into the bore 29. Then, as shown in FIG. 5, X-rays are irradiated from a plurality of view directions around the subject 6 with the slice thickness direction z of the subject 6 as an axis, and each subject view direction is viewed via the collimator 22. X-rays transmitted through the specimen 6 are detected by the X-ray detector 23 to generate projection data of the subject.

  The data collection unit 24 is provided for collecting data based on radiation detected by the X-ray detector 23. The data collection unit 24 collects projection data of the subject 6 based on the X-rays detected by the detection elements 23 a of the X-ray detector 23 and outputs the collected data to the operation console 3. As shown in FIG. 2, the data collection unit 24 includes a selection / addition switching circuit (MUX, ADD) 241 and an analog-digital converter (ADC) 242. The selection / addition switching circuit 241 selects projection data by the detection element 23a of the X-ray detector 23 in accordance with the control signal CTL303 from the central processing unit 30, or adds a combination thereof, and the result is analog- Output to the digital converter 242. The analog-digital converter 242 converts the projection data selected by the selection / addition switching circuit 241 or added in an arbitrary combination from an analog signal to a digital signal and outputs it to the central processing unit 30.

  As shown in FIG. 2, the X-ray controller 25 outputs a control signal CTL 251 to the X-ray tube 20 in accordance with a control signal CTL 301 from the central processing unit 30 to control X-ray irradiation. The X-ray controller 25 controls, for example, the tube current and irradiation time of the X-ray tube 20. Further, the X-ray controller 25 outputs a control signal CTL252 to the X-ray tube moving unit 221 in response to the control signal CTL301 from the central processing unit 30, and moves the radiation center of the X-ray tube 20 in the slice thickness direction z. To control.

  As shown in FIG. 2, the collimator controller 26 outputs a control signal CTL 261 to the collimator 22 in response to the control signal CTL 302 from the central processing unit 30 to shape the X-rays emitted from the X-ray tube 20. 22 is controlled.

  As shown in FIG. 1, the rotating unit 27 rotates in a predetermined direction in response to a control signal CTL 28 from the rotation controller 28. The rotation unit 27 includes an X-ray tube 20, an X-ray tube moving unit 21, a collimator 22, an X-ray detector 23, a data collection unit 24, an X-ray controller 25, and a collimator controller 26, As the rotating unit 27 rotates, the position with respect to the subject 6 carried into the bore 29 changes. By rotating the rotating unit 27, X-rays are irradiated from a plurality of view directions with the slice thickness direction z of the subject 6 as an axis, and X-rays transmitted through the subject 6 are detected.

  As shown in FIG. 2, the rotation controller 28 outputs a control signal CTL 28 to the rotation unit 27 based on a control signal CTL 304 from the central processing unit 30 of the operation console 3 and controls the rotation unit 27 to rotate.

  As shown in FIG. 1, the operation console 3 includes a central processing unit 30, an input device 31, a display device 32, and a storage device 33.

  FIG. 6 is a configuration diagram showing the configuration of the central processing unit 30 of the operation console 3.

  The central processing unit 30 is configured by a computer, for example, and includes a control unit 41 and a data processing unit 51 as shown in FIG.

  The control unit 41 irradiates the subject 6 with X-rays from the X-ray tube 20 based on scanning conditions for scanning the subject 6, and detects X-rays transmitted through the subject 6 with the X-ray detector 23. As described above, each part is controlled to perform scanning. Specifically, the control unit 41 outputs a control signal CTL 30a to each unit based on the scan condition, and causes the scan to be executed. For example, the control unit 41 outputs a control signal CTL 30 b to the imaging table 4, and causes the imaging table 4 to be carried into or out of the bore 29 of the scanning gantry 2. In addition, the control unit 41 outputs a control signal CTL 304 to the rotation controller 28 to rotate the rotation unit 27 of the scanning gantry 2. Further, the control unit 41 outputs a control signal CTL 301 to the X-ray controller 25 so that X-rays are emitted from the X-ray tube 20. And the control part 41 outputs the control signal CTL302 to the collimator controller 26, controls the collimator 22, and shape | molds X-ray | X_line. In addition, the control unit 42 outputs a control signal CTL 303 to the data collection unit 24 and controls to collect projection data obtained by the detection element 23 a of the X-ray detector 23.

  The data processing unit 51 includes an image generation unit 61, a scan condition setting unit 71, a temperature transition calculation unit 81, a scanable image number calculation unit 90, and a scan condition change unit 91.

  The image generation unit 61 reconstructs an image of the tomographic plane of the subject based on the projection data collected by the data collection unit 24. For example, the image generation unit 61 performs preprocessing such as sensitivity correction and beam hardening correction on projection data from a plurality of view directions by an axial scan, and then performs reconstruction using a filtered backprojection method. An image of the tomographic plane of the specimen 6 is reconstructed and generated.

  The scan condition setting unit 71 sets scan conditions under which the X-ray tube 20 emits X-rays to scan the subject based on a command input to the input device 31 by the operator. The scan condition setting unit 71, for example, as a scan condition, a scan method such as an axial scan method or a helical scan method, the number of scans corresponding to the number of captured images, a tube current value and a tube voltage value of the X-ray tube 20, and an X-ray irradiation Scan parameters such as time, slice position, and slice thickness are set and output to the control unit 41. Further, the scan condition setting unit 71 sets a scan condition so that a plurality of scans are grouped into a scan group based on a command input to the input device 31 by the operator, and a plurality of scans by the scan group are performed. For example, the scan condition setting unit 71 sets a scan under a condition for obtaining three captured images with a slice thickness of 5 mm as the first scan group, and performs a scan with a condition for obtaining three captured images with a slice thickness of 2.5 mm. Set as 2 scan groups.

  The temperature transition calculation unit 81 calculates the temperature transition of the X-ray tube 20. The temperature transition calculation unit 81 receives the temperature detection data D1 of the X-ray tube 20 from the X-ray tube temperature detection unit 20a, and calculates the temperature that changes from the temperature of the temperature detection data D1 corresponding to the time. For example, the temperature transition calculation unit 81 actually measures the temperature characteristics of the X-ray tube 20, acquires in advance an arithmetic expression indicating the temperature characteristics, and based on the arithmetic expression of the temperature characteristics of the X-ray tube 20, 20 temperature transitions are calculated. In addition, when the scan condition setting unit 71 sets the scan condition, the temperature transition calculation unit 81 sets the first temperature transition of the X-ray tube 20 under the scan condition set by the scan condition setting unit 71 as the temperature transition. Is calculated. Further, the temperature transition calculation unit 81 causes the scan condition changing unit 91 to set the X-ray tube 20 within a predetermined reference temperature range based on the first temperature transition of the X-ray tube 20 as described later. When the scan condition set by the scan condition setting unit 71 is changed, the second temperature transition of the X-ray tube 20 under the scan condition changed by the scan condition changing unit 91 is calculated. The temperature transition calculation unit 81 changes the temperature transition by the input device 31 as a temperature transition when the input device 31 performs an operation of changing the scan condition set by the scan condition setting unit 71 based on an instruction from the operator. The second temperature transition of the X-ray tube under the set scanning conditions is calculated.

  Based on the first temperature transition of the X-ray tube 20 calculated by the temperature transition calculation unit 81, the scanable image number calculation unit 90 is configured so that the X-ray tube 20 operates under the scan conditions set by the scan condition setting unit 71. The number of images that fall within the reference temperature range is calculated. For example, when a scan condition for obtaining 200 images is set by the scan condition setting unit 71, the scanable image number calculating unit 82 exceeds the reference temperature range of the X-ray tube 20 when the number exceeds 150. Is determined by the first temperature transition of the X-ray tube 20 calculated by the scan condition temperature transition calculator 81, up to 150 images are calculated as the number of images that can be captured by scanning.

  Based on the first temperature transition of the X-ray tube 20 calculated by the temperature transition calculation unit 81, the scan condition changing unit 91 sets the scan condition so that the X-ray tube 20 is within a predetermined reference temperature range. The scan condition set by the setting unit 71 is changed. For example, the scan condition changing unit 91 determines whether or not the temperature transition of the X-ray tube 20 is within the reference temperature range, and when the temperature transition of the X-ray tube 20 is outside the reference temperature range, a predetermined reference is determined. The scan conditions set by the scan condition setting unit 71 are changed so that the X-ray tube 20 is within the temperature range. For example, the scan condition changing unit 91 calculates a standby time during which the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71, and scans based on the calculated standby time. The scan condition set by the condition setting unit 71 is changed. For example, the scan condition changing unit 91 calculates the tube current supplied to the X-ray tube 20 so that the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71, Based on the calculated tube current, the scan condition set by the scan condition setting unit 71 is changed. Further, when the scan condition setting unit 71 sets the scan condition so that the scan condition setting unit 71 performs a plurality of scans, the X-ray tube 20 is set to the reference temperature in the scan condition set by the scan condition setting unit 71. A time interval between a plurality of scans that falls within the range is calculated, and the scan condition set by the scan condition setting unit 71 is changed based on the calculated time interval. The scan condition changing unit 91 sets a scan condition when the scan condition setting unit 71 groups a plurality of scans into a scan group and sets the scan condition so that a plurality of scans are performed by the scan group. Under the scanning conditions set by the unit 71, a time interval between scan groups is calculated so that the X-ray tube 20 is within the reference temperature range, and the scan condition setting unit 71 sets the time interval based on the calculated time interval. Change the scanned condition.

  The input device 31 of the operation console 3 is composed of input devices such as a keyboard and a mouse, for example. The input device 31 inputs various information such as scan conditions and information on the subject 6 to the central processing unit 30 based on an input operation by the operator. Further, the input device 31 performs an operation for changing the scan condition set by the scan condition setting unit 71 based on an instruction from the operator.

  The display device 32 displays an image of the tomographic plane of the subject reconstructed by the image generation unit 61 based on a command from the central processing device 30. Further, the display device 32 displays the temperature transition of the X-ray tube 20 calculated by the temperature transition calculator 81. In the present embodiment, the display device 32 displays both the first and second temperature transitions calculated by the temperature transition calculation unit 81 in a graph. That is, the display device 32 displays the first temperature transition of the X-ray tube 20 under the scan condition set by the scan condition setting unit 71. Further, the display device 32 is set by the scan condition setting unit 71 such that the X-ray tube 20 is within the reference temperature range determined in advance by the scan condition changing unit 91 based on the first temperature transition. The second temperature transition of the X-ray tube 20 in the scan condition in which the scan condition is changed is displayed. Further, when the scan condition changing unit 91 changes the scan condition set by the scan condition setting unit 71 based on a command input to the input device 31 by the operator, the X-ray tube in the changed scan condition 20 temperature transitions are displayed in the same manner.

  The storage device 33 is configured by a memory, and stores various data such as an image of a tomographic plane of the subject reconstructed by the image generation unit 61, a program, and the like. In the storage device 33, the stored data is accessed to the central processing unit 30 as necessary.

  The imaging table 4 includes a cradle on which the subject 6 to be imaged is placed and a carry-in / out unit that carries the cradle into and out of the bore. The imaging table 4 carries the subject 6 in or out of the bore 29 of the scanning gantry 2 based on a control signal from the operation console 3.

  The X-ray CT apparatus 1 in the present embodiment corresponds to the radiation tomography apparatus of the present invention. The X-ray tube 20 in this embodiment corresponds to the radiation generating means of the present invention. The display device 32 in the present embodiment corresponds to a display unit of the present invention. The scan condition setting unit 71 in the present embodiment corresponds to the setting unit of the present invention. Moreover, the temperature transition calculation part 81 in this embodiment is corresponded to the calculation part of this invention. The scan condition changing unit 91 in the present embodiment corresponds to the changing unit of the present invention. The input device 31 of this embodiment corresponds to the operation unit of the present invention.

  Hereinafter, the operation of the X-ray CT apparatus 1 of the present embodiment will be described.

  FIG. 7 is a flowchart showing the operation when imaging a subject using the X-ray CT apparatus 1 of the present embodiment.

  As shown in FIG. 7, first, a scout scan is performed (S11).

  When performing a scout scan of the subject 6, each parameter condition of the scout scan condition is input to the input device 31 by the operator, and an operation signal based on the input is output to the central processing unit 30.

  Then, the control unit 41 of the central processing unit 30 outputs control signals CTL 30 a and CTL 30 b to the scanning gantry 2 and the imaging table 4. As a result, the control unit 41 outputs the control signal CTL 30 b to the imaging table 4 and carries the imaging table 4 into the bore 29 of the scanning gantry 2. Then, the control unit 41 outputs a control signal CTL 301 to the X-ray controller 25 so that X-rays are emitted from the X-ray tube 20, and also outputs a control signal CTL 302 to the collimator controller 26 to control the collimator 22 to perform X X-rays from the tube 20 are formed. Further, the control unit 41 outputs a control signal CTL 303 to the data collection unit 24 and controls to collect projection data obtained by the detection element 23a of the X-ray detector 23. Then, based on the projection data collected by the data collection unit 24, the image generation unit 61 generates a scout image of the subject, and the display device 32 displays the scout image.

  Next, the main scanning condition is set (S21).

  When setting the main scan condition, the operator inputs each parameter condition of the main scan condition to the input device 31 based on the scout image. Then, the input device 31 outputs a command based on the input to the scan condition setting unit 71 of the central processing unit 30. The scan condition setting unit 71 sets scan conditions for the X-ray tube 20 to irradiate X-rays and scan the subject based on a command input to the input device 31 by the operator. For example, as scanning conditions, a scanning method such as an axial scanning method or a helical scanning method, the number of scans corresponding to the number of captured images, tube current value and tube voltage value of the X-ray tube 20, X-ray irradiation time, slice position, slice thickness The scan condition setting unit 71 sets scan parameters such as Specifically, the scan conditions are set so that 200 images are obtained at a tube current of 500 mA.

  Next, the temperature transition of the X-ray tube 20 is calculated (S31).

  When calculating the temperature transition of the X-ray tube 20, the temperature detection data D1 of the X-ray tube 20 from the X-ray tube temperature detection unit 20a and the scan condition data set by the scan condition setting unit 71 are used as the temperature. In the scan condition acquired by the transition calculation unit 81 and set by the scan condition setting unit 71, the temperature that changes from the temperature of the temperature detection data D1 at that time is associated with the time, and the first temperature transition is calculated as the temperature transition. The unit 81 calculates.

  For example, the temperature transition calculation unit 81 calculates the temperature transition of the X-ray tube 20 based on a previously obtained arithmetic expression for the temperature characteristic of the X-ray tube 20.

  Next, it is determined whether or not the temperature transition of the X-ray tube 20 is within the reference temperature range (S41).

  Here, based on the first temperature transition of the X-ray tube 20 calculated by the temperature transition calculation unit 81, the scan condition changing unit 91 determines whether or not the temperature transition of the X-ray tube 20 is within the reference temperature range. .

  When the temperature transition of the X-ray tube 20 is within the reference temperature range, the main scan is performed (S71). When the temperature transition of the X-ray tube 20 is within the reference temperature range, the main scan is performed. The condition is changed (S51).

  When changing the main scan condition, the scan condition changing unit 91 changes the scan condition set by the scan condition setting unit 71 so that the X-ray tube 20 is within a predetermined reference temperature range. .

  For example, in the scan condition set by the scan condition setting unit 71, a standby time during which the X-ray tube 20 is within the reference temperature range is calculated, and the scan condition setting unit 71 sets the standby time based on the calculated standby time. Change the scan conditions. In addition, for example, under the scan condition set by the scan condition setting unit 71, the tube current supplied to the X-ray tube 20 is calculated so that the X-ray tube 20 is within the reference temperature range, and the calculated tube current is calculated. Based on the above, the scan condition set by the scan condition setting unit 71 is changed.

  Then, the temperature transition calculation unit 81 calculates the second temperature transition of the X-ray tube 20 under the scan condition changed by the scan condition changing unit 91. At this time, the scanable image number calculation unit 90 calculates the number of images that can be photographed by scanning so that the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71. . When the input device 31 performs an operation for changing the scan condition set by the scan condition setting unit 71 based on an instruction from the operator, the temperature transition calculation unit 81 uses the input device 31 as a temperature transition. The second temperature transition of the X-ray tube under the scan condition changed by the above is calculated.

  Next, the temperature transition of the X-ray tube 20 is displayed and confirmed (S61).

  FIG. 8 is a view showing a display image of the temperature transition of the X-ray tube 20. In FIG. 8, the horizontal axis represents the number of images continuously captured corresponding to time, and the vertical axis represents the temperature of the X-ray tube 20 calculated corresponding to the horizontal axis.

  As shown in FIG. 8, the display device 32 displays the temperature transition of the X-ray tube 20 calculated by the temperature transition calculator 81. In the present embodiment, the display device 32 displays the first temperature transition H11 of the X-ray tube 20 under the scan condition set by the scan condition setting unit 71. Further, the display device 32 displays the upper limit value of the reference temperature range of the X-ray tube 20. Then, based on the first temperature transition of the X-ray tube 20 calculated by the temperature transition calculation unit 81, an image in which the X-ray tube 20 falls within the reference temperature range under the scan condition set by the scan condition setting unit 71. The display device 32 displays the result of calculating the number of images by the scanable image number calculation unit 90. Further, the display device 32 is set by the scan condition setting unit 71 such that the X-ray tube 20 is within the reference temperature range determined in advance by the scan condition changing unit 91 based on the first temperature transition. The second temperature transitions H21 and H22 of the X-ray tube 20 under the scan conditions in which the scan conditions are changed are displayed.

  As shown in FIG. 8, in this embodiment, the first temperature transition H11 of the X-ray tube 20 is shown according to the scan condition for generating 200 images at a tube current of 500 mA. Here, up to 150 images are shown. It shows that the temperature of the X-ray tube 20 reaches the upper limit under the scanning conditions for generating an image.

  Further, in FIG. 8, based on the standby time calculated by the scan condition changing unit 91 so that the X-ray tube 20 is within the reference temperature range under the scan condition set by the scan condition setting unit 71, the scan condition changing unit The display device 32 displays the second temperature transition H <b> 21 of the X-ray tube 20 under the scan condition changed by 91. In FIG. 8, for example, the second temperature transition H21 when the main scanning condition is changed with a standby time of 50 seconds is displayed.

  Further, for example, based on the tube current of the X-ray tube 20 calculated by the scan condition changing unit 91 so that the X-ray tube 20 falls within the reference temperature range under the scan condition set by the scan condition setting unit 71, the scan condition is set. The display device 32 displays the second temperature transition H22 of the X-ray tube 20 under the scan condition changed by the changing unit 91. In FIG. 8, for example, the second temperature transition H22 when the main scan condition is changed so that the tube current is 440 mA with respect to the tube current before the change is 500 mA is displayed.

  As shown in FIG. 8, the image of the temperature distribution displayed on the display device 32 is observed, and the operator confirms the temperature transition. As a result of the confirmation, when the scanning condition is further changed, the process returns to S51, and the operator inputs the scanning parameter to be changed to the input device 31. Specifically, an instruction to change the tube voltage from 440 mA to 460 mA and to change the standby time from 50 sec to 10 sec is input. Then, based on the input scan parameter, the scan condition set by the scan condition setting unit 71 is changed, and the temperature transition of the X-ray tube 20 under the changed scan condition is displayed in the same manner. If the scan condition is not changed, the scan is performed (S71) under the main scan condition that results in the second temperature transition.

  When performing the main scan, the control unit 41 outputs the control signals CTL30a and CTL30b to the scanning gantry 2 and the imaging table 4 based on the main scan condition set or changed as described above. As a result, the control unit 41 outputs a control signal CTL 304 to the rotation controller 28 to rotate the rotation unit 27 of the scanning gantry 2. Further, the control unit 41 outputs a control signal CTL 301 to the X-ray controller 25 so that X-rays are emitted from the X-ray tube 20. And the control part 41 outputs the control signal CTL302 to the collimator controller 26, controls the collimator 22, and shape | molds X-ray | X_line. Further, the control unit 41 outputs a control signal CTL 303 to the data collection unit 24 and controls to collect projection data obtained by the detection element 23a of the X-ray detector 23. Thereafter, the image generation unit 61 reconstructs and generates an image of the subject 6 based on the collected projection data. Then, the display device 32 displays an image reconstructed and generated by the image generation unit 61.

  As described above, according to the present embodiment, the temperature transition calculation unit 81 calculates the temperature transition of the X-ray tube 20, and the temperature transition of the X-ray tube 20 calculated by the temperature transition calculation unit 81 is displayed on the display device 32. Is displayed. Here, the scan condition setting unit 71 sets scan conditions for the X-ray tube to irradiate X-rays and scans the subject, and the temperature transition calculation unit 81 uses the scan conditions set by the scan condition setting unit 71. A first temperature transition of the X-ray tube 20 is calculated. Further, based on the first temperature transition calculated by the scan condition calculation unit 81, the scan condition set by the scan condition setting unit 71 so that the X-ray tube 20 is within the reference temperature range is changed to the scan condition change unit. 91 changes. At this time, the temperature transition calculation unit 81 calculates the second temperature transition of the X-ray tube 20 under the scan condition changed by the scan condition change unit 91. Then, the display device 32 displays both the first temperature distribution and the second temperature transition calculated by the temperature transition calculation unit 81.

  For this reason, in this embodiment, since the state of the temperature transition of the X-ray tube in the set scan condition and the changed scan condition is clearly shown, the operator obtains the determination criteria and makes the work efficient. Can be easily done.

<Embodiment 2>
The second embodiment of the present invention will be described below.

  In the present embodiment, unlike the first embodiment, the scan condition setting unit 71 sets scan conditions so that a plurality of scans are performed at time intervals t1. Then, the scan condition changing unit 91 calculates time intervals between a plurality of scans such that the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71. Based on the time interval t2, the scan condition set by the scan condition setting unit 71 is changed. As described above, the present embodiment is the same as the first embodiment except that the scan condition changing unit 91 changes the time interval between a plurality of scans without changing the standby time or the tube current value. For this reason, description is abbreviate | omitted about the overlapping part.

  FIG. 9 is a diagram for explaining the second embodiment of the present invention.

  9A is a time chart of the scan condition set by the scan condition setting unit 71, and FIG. 9B is a time chart of the scan condition changed by the scan condition changing unit 91. . 9A and 9B, the vertical axis represents the tube current value, and the horizontal axis represents time. FIG. 9C shows an image related to the temperature distribution displayed on the display device 32.

  As shown in FIG. 9A, the scan condition setting unit 71 sets the scan conditions so that a plurality of scans of the first scan S11 and the second scan S21 are performed at time intervals t1.

  Then, as shown in FIG. 9B, the scan condition changing unit 91 performs scanning between a plurality of scans such that the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71. The time interval t2 is calculated, and the scan condition set by the scan condition setting unit 71 is changed based on the calculated time interval t2. For example, the scan condition changing unit 91 changes the scan condition so that the time interval t2 is increased by 10 seconds from the time interval t1 between a plurality of scans set by the scan condition setting unit 71.

  Similar to the above-described embodiment, the temperature transition calculation unit 81 calculates the first temperature transition of the X-ray tube 20 under the scan conditions set by the scan condition setting unit 71. Further, the temperature transition calculation unit 81 calculates the second temperature transition of the X-ray tube 20 under the scan condition changed by the scan condition changing unit 91.

  Thereafter, as shown in FIG. 9C, the display device 32 displays the first temperature transition H31 and the second temperature transition H41 calculated by the temperature transition calculation unit 81 in a graph.

  Specifically, the first temperature transition H11 of the X-ray tube 20 according to the initial main scan condition for generating 200 images at a tube current of 500 mA is shown. Here, the scan for generating up to 150 images is shown. It shows that the temperature of the X-ray tube 20 becomes the upper limit under conditions.

  Further, for example, the main scan condition is changed based on the fact that the scan condition is changed to the time interval t2 increased by 10 seconds from the time interval t1 between the plurality of scans set by the scan condition setting unit 71. The second temperature transition H21 at the time of the operation is displayed.

  As described above, according to the present embodiment, similarly to the first embodiment, the temperature transition calculation unit 81 calculates the temperature transition of the X-ray tube 20, and the X-ray tube 20 calculated by the temperature transition calculation unit 81. Is displayed on the display device 32. For this reason, in this embodiment, since the state of the temperature transition of the X-ray tube in the set scan condition and the changed scan condition is clearly shown, the operator obtains the determination criteria and makes the work efficient. Can be easily done.

<Embodiment 3>
The third embodiment of the present invention will be described below.

  In the present embodiment, unlike the first embodiment, the scan condition setting unit 71 groups a plurality of scans to form a scan group, and sets the scan conditions so that a plurality of scans by the scan group are performed. Then, the scan condition changing unit 91 calculates the time interval between the scan groups so that the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71, and the calculated time Based on the interval, the scan condition set by the scan condition setting unit 71 is changed. As described above, the present embodiment is the same as the first embodiment except that the scan condition changing unit 91 changes the time interval between a plurality of scan groups without changing the standby time or the tube current value. For this reason, description is abbreviate | omitted about the overlapping part.

  FIG. 10 is a diagram for explaining the third embodiment of the present invention.

  10A is a time chart of the scanning conditions set by the scanning condition setting unit 71, and FIG. 10B is a time chart of the scanning conditions changed by the scanning condition changing unit 91. . 10A and 10B, the vertical axis represents the tube current value, and the horizontal axis represents time. FIG. 10C shows an image related to the temperature distribution displayed on the display device 32.

  As shown in FIG. 10A, the scan condition setting unit 71 sets the first to third scans S31, S32, and S33 as the first scan group G11, and the fourth to sixth scans S41, S42, and S43. Is set as a second scan group G21, and a scan condition is set so that scanning is performed with a time interval t11 between the first and second scan groups G11 and G21.

  Then, as shown in FIG. 10B, the scan condition changing unit 91 includes a plurality of scan groups between which the X-ray tube 20 is within the reference temperature range under the scan conditions set by the scan condition setting unit 71. The time interval t21 is calculated, and the scan condition set by the scan condition setting unit 71 is changed based on the calculated time interval t21. For example, the scan condition changing unit 91 changes the scan condition so that the time interval t21 is increased by 10 seconds from the time interval t11 between the plurality of scan groups set by the scan condition setting unit 71.

  Similar to the above-described embodiment, the temperature transition calculation unit 81 calculates the first temperature transition of the X-ray tube 20 under the scan conditions set by the scan condition setting unit 71. Further, the temperature transition calculation unit 81 calculates the second temperature transition of the X-ray tube 20 under the scan condition changed by the scan condition changing unit 91.

  Thereafter, as shown in FIG. 10C, the display device 32 displays the first temperature transition H51 and the second temperature transition H61 calculated by the temperature transition calculation unit 81 in a graph.

  Specifically, the first temperature transition H11 of the X-ray tube 20 according to the initial main scan condition for generating 200 images at a tube current of 500 mA is shown. Here, the scan for generating up to 150 images is shown. It shows that the temperature of the X-ray tube 20 becomes the upper limit under conditions.

  Further, for example, the main scan condition is changed based on the change of the scan condition so that the time interval t21 is increased by 10 seconds from the time interval t11 between the plurality of scans set by the scan condition setting unit 71. The second temperature transition H21 at the time of the operation is displayed.

  As described above, according to the present embodiment, similarly to the first embodiment, the temperature transition calculation unit 81 calculates the temperature transition of the X-ray tube 20, and the X-ray tube 20 calculated by the temperature transition calculation unit 81. Is displayed on the display device 32. For this reason, in this embodiment, since the state of the temperature transition of the X-ray tube in the set scan condition and the changed scan condition is clearly shown, the operator obtains the determination criteria and makes the work efficient. Can be easily done.

  In implementing the present invention, the present invention is not limited to the above-described embodiment, and various modifications can be employed.

  For example, in the above embodiment, an example in which projection data of a subject is acquired using X-rays as radiation and an image of the subject is generated has been described. However, radiation is not limited to X-rays. For example, radiation such as gamma rays may be used.

FIG. 1 is a block diagram showing the overall configuration of the X-ray CT apparatus according to the first embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a main part of the X-ray CT apparatus according to the first embodiment of the present invention. FIG. 3 is a configuration diagram showing an X-ray detection module constituting the X-ray detector according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating the interrelationship among the X-ray tube, the collimator, and the X-ray detector according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating the interrelationship among the X-ray tube, the collimator, and the X-ray detector according to the first embodiment of the present invention. FIG. 6 is a configuration diagram showing the configuration of the central processing unit of the operation console according to the first embodiment of the present invention. FIG. 7 is a flowchart showing an operation when imaging a subject using the X-ray CT apparatus according to the first embodiment of the present invention. FIG. 8 is a view showing a display image of the temperature transition of the X-ray tube in the first embodiment according to the present invention. FIG. 9 is a diagram for explaining the second embodiment of the present invention. FIG. 10 is a diagram for explaining the third embodiment of the present invention.

Explanation of symbols

1 X-ray CT apparatus (radiation tomography apparatus)
2 ... Scanning gantry,
3. Operation console,
4 ... Shooting table,
6 ... Subject,
20 ... X-ray tube (radiation generating means),
21 ... X-ray tube moving part,
22 ... Collimator,
23 ... X-ray detector,
23A ... X-ray detection module,
23a ... detecting element,
24 ... Data collection unit,
241 ... Selection / addition switching circuit,
242 ... Analog-to-digital converter,
25 ... X-ray controller,
26 ... Collimator controller,
27 ... rotating part,
28 ... Rotation controller,
29 ... Boa,
30 ... Central processing unit,
31 ... Input device,
32. Display device (display unit),
33 ... Storage device,
41. Control unit,
51: Data processing unit,
61 ... Image reconstruction unit,
71 ... Scan condition setting part (setting part),
81 ... temperature transition calculation part (calculation part),
90: Scannable image number calculating section,
91 ... Scan condition changing section (changing section)

Claims (10)

A radiation tomography apparatus that generates an image of a tomographic plane of the subject based on projection data obtained by detecting radiation that is irradiated onto the subject from a radiation generating means and transmitted through the subject,
A calculating unit for calculating a temperature transition of the radiation generating means;
A radiation tomography apparatus comprising: a display unit configured to display a temperature transition of the radiation generation unit calculated by the calculation unit. A setting section for setting a scanning condition for the radiation generating means to irradiate the radiation and scan the subject;
The radiation tomography apparatus according to claim 1, wherein the calculation unit calculates, as the temperature transition, a first temperature transition of the radiation generating unit under the scan condition set by the setting unit. Based on the first temperature transition calculated by the calculation unit, a change unit that changes the scan condition set by the setting unit so that the radiation generating unit is within a reference temperature range,
The radiation tomography apparatus according to claim 2, wherein the calculation unit calculates a second temperature transition of the radiation generating unit under the scan condition changed by the changing unit as the temperature transition. The radiation tomography apparatus according to claim 3, wherein the display unit displays both the first and second temperature transitions calculated by the calculation unit. The setting unit sets the scan condition to perform a plurality of scans,
The changing unit calculates a time interval between a plurality of scans such that the radiation generating unit is within a reference temperature range under the scan condition set by the setting unit, and based on the calculated time interval The radiation tomography apparatus according to claim 3, wherein the scan condition set by the setting unit is changed. The setting unit groups a plurality of scans to form a scan group, and sets the scan condition to perform a plurality of scans by the scan group,
The change unit calculates a time interval between the scan groups so that the radiation generating unit is within a reference temperature range under the scan condition set by the setting unit, and based on the calculated time interval The radiation tomography apparatus according to claim 3, wherein the scan condition set by the setting unit is changed. The changing unit calculates a standby time during which the radiation generating unit is within a reference temperature range under the scan conditions set by the setting unit, and is set by the setting unit based on the calculated standby time. The radiation tomography apparatus according to claim 3, wherein the scanning condition is changed. The changing unit calculates a tube current to be supplied to the radiation generating unit so that the radiation generating unit is within a reference temperature range under the scan condition set by the setting unit, and the calculated tube current is calculated. The radiation tomography apparatus according to claim 3, wherein the scan condition set by the setting unit is changed based on the setting. The radiation tomography apparatus according to claim 1, wherein the display unit displays the temperature transition in a graph. An operation unit for performing an operation of changing the scan condition set by the setting unit based on an instruction from an operator;
The radiation tomography apparatus according to any one of claims 1 to 8, wherein the calculation unit calculates a second temperature transition of the radiation generating unit under the scan condition changed by the operation unit as the temperature transition.

Images