JP2006349406A - Computer tomographic photographing system and ageing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically perform the proper ageing operation under a condition corresponding to a system stop time in a computer tomographic photographing system. <P>SOLUTION: The computer tomographic photographing system is equipped with an automatic ageing part 9 for automatically performing ageing operation for gradually boosting voltage up to desired set voltage at the time of rising of the system. The automatic ageing part includes a stop period calculating part 17 for calculating the system stop time on the basis of an inputted next photographing schedule and an ageing condition setting part 18 for setting the ageing condition corresponding to the system stop time calculated in the stop period calculating part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a computed tomography apparatus typified by an X-ray CT apparatus, and more particularly to a computed tomography apparatus having an automatic aging function.

  A computer tomography apparatus, for example, an X-ray CT apparatus, generally irradiates a subject with X-rays generated by an X-ray source in the X-ray source device, and thereby detects X-rays transmitted through the subject with a detection device. A tomographic image of the subject is obtained by an image reconstruction process in which an output signal from the detection apparatus is subjected to a filtering process in a frequency space by Fourier transform and then subjected to inverse Fourier transform.

  As the X-ray source in the X-ray CT apparatus, a DC voltage X-ray source, an accelerator, or the like is used. In these radiation sources, (1) high-velocity cations collide with a substance, (2) the substance is heated to a high temperature and electrons are emitted (thermoelectron emission), and (3) light is applied to the substance and photoelectrons are emitted. Ejecting electrons (photoelectric effect), (4) ionizing a gas body by radiation, (5) applying a strong electric field to a metal surface and extracting electrons (field emission) It accelerates with voltage and irradiates a heavy metal target such as tungsten to emit X-rays by bremsstrahlung.

  The efficiency with which accelerated electrons emit X-rays is about several percent, and the rest is heat. Therefore, the X-ray source is equipped with a cooling mechanism. However, if the target is rapidly irradiated with high-energy electrons, the thermal load becomes too great and the risk of target damage increases. Therefore, it is normal to perform an aging operation to prevent such damage. The aging operation is an operation method at the time of starting up the device that does not suddenly apply a high voltage to the X-ray source device at the time of starting up the device, and gradually raises the voltage from a low voltage to a desired set voltage. Thus, it is possible to avoid the problem that an excessive load is placed on the X-ray source due to a sudden rise in heat load.

  Aging operation is an industrial X-ray CT system with a large output of the X-ray source, about 30 minutes even when the X-ray source is used every day, 1 hour or more after a long stop after 3 days or more Take it. During this aging operation, the imaging operation cannot be performed and the dead time is reached. Therefore, in order to be able to perform the imaging work with the X-ray CT apparatus more efficiently, the worker in charge of the aging operation must go to work earlier than other workers and perform the aging operation. Is required.

  Regarding such an aging operation, a technique is known in which an X-ray CT apparatus has a function of automatically performing an aging operation in accordance with a schedule of imaging by the X-ray CT apparatus (for example, Patent Document 1). According to this technique, it is possible to perform an aging operation without imposing a burden on an operator engaged in the operation of the X-ray CT apparatus, and it is possible to increase the efficiency of the imaging work by the X-ray CT apparatus.

JP 7-148154 A

  In the automatic aging operation function disclosed in Patent Document 1, the necessity of aging operation is determined according to the imaging schedule, and if aging operation is necessary, a predetermined aging operation is performed to start up the X-ray CT apparatus. If the aging operation is unnecessary, the X-ray CT apparatus is started up without the aging operation, and the aging operation is alternative. Such an automatic aging operation function is sufficiently effective in a medical X-ray CT apparatus. That is, the medical X-ray CT apparatus is frequently used and rarely stops for several days. In general, an X-ray CT apparatus for medical use does not have a very high output from an X-ray source. For this reason, there is no problem even with an automatic aging operation function that can be used alternatively or not.

  However, the industrial X-ray CT apparatus has a problem with the automatic aging operation function of Patent Document 1. In many cases, industrial X-ray CT apparatuses have uneven use and stop for several days. In general, an industrial X-ray CT apparatus applies a high voltage such as several hundred kV to several MV to the X-ray source. For this reason, if the automatic aging operation function is an alternative of whether or not to perform the aging operation, there is a problem that aging becomes inappropriate or unnecessary aging is performed.

  The present invention has been made in the background as described above, and by appropriately performing appropriate aging operation under conditions according to the stop time, it is possible to effectively avoid inappropriate aging and useless aging. It is an object of the present invention to provide a computer tomography apparatus capable of performing the same, and to provide an aging method in such a computer tomography apparatus.

  For the above purpose, in the present invention, in the computed tomography apparatus including an automatic aging unit that automatically performs an aging operation for gradually increasing the voltage to a desired setting voltage when the apparatus is started up, the automatic aging unit is input. A stop period calculation unit that calculates an apparatus stop time based on the next imaging schedule, and an aging condition setting unit that sets an aging condition according to the apparatus stop time obtained by the stop period calculation unit. It is said.

  According to the present invention, in the above computed tomography apparatus, the automatic aging unit further includes a stop time / aging type table in which the relationship between the aging type and the stop time in the aging condition is obtained and tabulated in advance. However, the aging type corresponding to the stop time is searched from the stop time / aging type table so that it can be set as the aging condition.

  In the present invention, for the computed tomography apparatus as described above, as the aging type in the aging condition, a step-up type that repeats step-up in the step-up process up to the set voltage is provided. A boosting step number setting unit for setting the number of steps is further included in the automatic aging unit.

  In addition, in the present invention, for the above other purposes, in the aging method in which the computer tomography apparatus automatically performs the aging operation for gradually increasing the voltage to a desired set voltage when the apparatus is started up, the next imaging is started after the imaging operation is completed. Step of inputting the scheduled date and time, step of calculating the device stop time until the next imaging start scheduled date and time, imaging operation of the next scheduled from a plurality of aging types typed by the aging time according to the length of the device stop time A step of setting an aging type for the aging operation based on the set aging type and the next imaging start scheduled date and time, and a set aging operation It includes a step of performing an aging operation at the start time. It is set to.

  In the present invention, an apparatus stop time is calculated by the stop period calculation unit based on the next imaging schedule that is input, and an aging condition according to the apparatus stop time is selectively set by the aging condition setting unit. The aging operation is automatically performed in For this reason, the aging operation can be performed under the optimum conditions according to the apparatus stop time, and the aging time is too short and improper aging that places a burden on the radiation source. It is possible to effectively avoid useless aging that would waste power.

  Hereinafter, modes for carrying out the present invention will be described. FIG. 1 shows the configuration of an X-ray CT apparatus that is a computed tomography apparatus according to an embodiment. The X-ray CT apparatus of the present embodiment includes an X-ray source device 1, a rotary table 2, a translation mechanism 3, a vertical movement mechanism 4, a collimator 5, a detection device 6, a central control unit 7, an imaging unit 8, and an automatic aging unit 9. It has.

  The X-ray source device 1 irradiates X-ray R generated by the X-ray source 1 s toward the subject M placed on the rotary table 2. X-rays that have passed through the subject M are narrowed down by a collimator 5 for preventing incidence of scattered radiation and the like, and enter the detection device 6. The detection device 6 is configured by arranging a plurality of detectors 11 in a row or a plane. X-rays incident on the detection device 6, more specifically, X-rays incident on each detector 11 in the detection device 6 are converted into current signals by each detector 11, and each detector 11 outputs the current signal. To do. The current signal from each detector 11 is input to the imaging unit 8.

  The imaging unit 8 includes a detection circuit unit 12, an A / D conversion unit 13, a signal processing unit 14, and an image display unit 15, and performs imaging processing while being controlled by the central control unit 7. Specifically, the current signal from each detector 11 is subjected to current-voltage conversion by the detection circuit unit 12, and the voltage signal obtained thereby is converted from an analog signal to a digital signal by the A / D conversion unit 13. Convert. Then, the signal processing unit 14 performs image reconstruction processing based on the digital signal from the A / D conversion unit 13, and displays the image thus obtained on a display device or the like not shown in the figure.

  The rotary table 2 performs rotation for rotating the subject M during imaging. The translation mechanism 3 causes the rotary table 2 to translate in a direction perpendicular to a straight line connecting the center of the X-ray source device 1 and the center of the detection device 6. The vertical movement mechanism 4 causes the rotary table 2 to move up and down via the translation mechanism 3. The rotary table 2, the translation mechanism 3 and the vertical movement mechanism 4 are collectively referred to as a scanner.

  The automatic aging unit 9 is configured as a computer program mounted on the central control unit 7, and includes an imaging plan input unit 16, a stop period calculation unit 17, an aging condition setting unit 18, an aging start time monitoring unit 19, and an aging operation. An execution unit 20 and a stop time / aging type table 21 are included.

  FIG. 2 shows the flow of apparatus operation including automatic aging operation by the automatic aging unit 9 in the X-ray CT apparatus according to the present embodiment. The automatic aging operation is started by the automatic aging unit 9 a predetermined time before the time when the imaging operation is started (step 101). The automatic aging operation is performed under the aging conditions set by the automatic aging unit 9. The automatic aging operation based on the predetermined aging condition ends before the imaging operation start time (step 102). When the automatic aging operation ends, the imaging operation becomes possible, and the imaging operation is started (step 103). When necessary imaging is finished, the imaging operation is finished (step 104). When the imaging operation is completed, the next imaging schedule is input to the automatic aging unit 9 by the imaging schedule input unit 16 (step 105), and then the X-ray CT apparatus is stopped by turning off the power (step 106). The next imaging schedule is input by inputting the scheduled start date and time of the next imaging. If there is no next imaging plan, “no plan” is input.

  The automatic aging unit 9 that has received an input for the next imaging schedule calculates the stop time of the X-ray CT apparatus until the next imaging schedule by the stop period calculation unit 17 (step 107), and based on that, for the next scheduled imaging operation. The aging condition in the aging operation is set by the aging condition setting unit 18 (step 108). The stop time is calculated as the time from the stop time of the X-ray CT apparatus in step 106 to the scheduled start date and time of the next imaging. When “no plan” is input, the stop time is “long stop”.

  The aging condition includes an aging type relating to the length of time (aging time) required to boost the voltage applied to the X-ray source device 1 to the desired set voltage when the device is started up, and a step in the boosting process to the desired set voltage. In particular, there are the number of boosting steps when the boosting is repeated, the aging operation start time, and the like. The aging condition setting unit 18 in the present embodiment includes an aging type setting unit 22, a step-up step number setting unit 23, and a start time setting unit 24, and these function units set aging conditions related to the next imaging schedule. To do.

  The aging type is set based on the stop time obtained in step 107. More specifically, a plurality of aging types that are typed by an aging time having a length corresponding to the length of the stop time are provided. For example, if the stop time is within 24 hours, the aging time is 30 minutes, and if the stop time is 24 hours or more and 72 hours, the aging time is 60 minutes, the stop time is 72 hours or more. Alternatively, in the case of “no long-term stop” in the case of “no plan”, an example of the aging type is a stepped boost type that boosts over 60 minutes while repeating stepwise boosting in a predetermined mode. FIG. 3 shows an example of the relationship between boosting and time in each aging type. The stop time / aging type table 21 is a table in which the relationship between the plurality of aging types and the stop time, and the relationship between the number of boosting steps and the stop time in the case where the boosting is repeated in stages, are obtained in advance and tabulated. Therefore, the aging type is set when the aging type setting unit 22 searches the aging type corresponding to the stop time in step 107 from the stop time / aging type table 21. When setting the stepwise boost type aging time, the aging type setting unit 22 obtains the aging time length from the stop time / aging type table 21, and sets the number of boosting steps according to the time length. The unit 23 obtains and sets it. When the stop time is shorter than a certain value, for example, 6 hours or less, the aging type setting unit 22 may be set to “no aging operation”.

  When the aging time is set, the start time setting unit 24 sets the aging operation start time based on the aging time and the next imaging start scheduled date and time. In response to this, the aging start time monitoring unit 19 monitors the aging operation start time (step 109). When the aging operation start time is reached, the aging operation execution unit 20 executes the aging operation (step 110).

  As described above, in the present invention, the aging conditions are set such that the aging type is changed according to the stop time of the X-ray CT apparatus, and the aging operation is automatically performed under the aging conditions. For this reason, the aging operation can be performed under the optimum conditions according to the stop time of the X-ray CT apparatus, and the aging time is too short, and improper aging or necessary that imposes a mischievous burden on the X-ray source apparatus 1 As described above, it is possible to effectively avoid useless aging that consumes power by consuming too much time for aging.

  The present invention enables a computer tomography apparatus to automatically perform an appropriate aging operation under conditions according to a stop time, and can be widely used in the field of computer tomography apparatuses.

It is a figure which shows the structure of the X-ray CT apparatus by one Embodiment. It is a figure which shows the flow of apparatus operation | movement in the X-ray CT apparatus of FIG. It is a figure which shows the example of the pressure | voltage rise and time in each aging type.

Explanation of symbols

9 Automatic Aging Unit 17 Stop Period Calculation Unit 18 Aging Condition Setting Unit 21 Stop Time / Aging Type Table 23 Boosting Step Number Setting Unit

Claims (4)

In a computer tomography apparatus having an automatic aging unit that automatically performs an aging operation in which the voltage is gradually increased to a desired setting voltage when the apparatus is started up,
The automatic aging unit includes a stop period calculation unit that calculates a device stop time based on the next imaging schedule that is input, and an aging condition setting that sets an aging condition according to the device stop time obtained by the stop period calculation unit A computer tomography apparatus characterized by including a section.   The automatic aging unit further includes a stop time / aging type table in which the relationship between the aging type and the stop time in the aging condition is previously obtained and tabulated, and the stop time is determined from the stop time / aging type table. The computer tomography apparatus according to claim 1, wherein the aging type corresponding to the item can be searched and set as the aging condition.   As the aging type in the aging condition, there is provided a step-up step-up type that repeats step-up in the step-up process up to the set voltage, and the step-up step number setting unit that sets the step-up step number in the step-up step-up type is provided in the automatic step. The computed tomography apparatus according to claim 1, further comprising an aging unit. In an aging method for automatically causing the computer tomography apparatus to perform an aging operation for gradually increasing the voltage to a desired setting voltage when the apparatus is started up,
A step of inputting a scheduled start date and time of the next imaging after the end of the imaging operation, a step of calculating a device stop time until the next scheduled start date and time of imaging, and a plurality of types classified by aging times corresponding to the length of the device stop time Set the aging type for the next scheduled imaging operation from the aging type based on the device stop time calculated in the above step, and set the aging operation start time based on the set aging type and the next imaging start scheduled date and time And an aging method including performing an aging operation at a set aging operation start time.

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