JP2010284374A - X-ray ct apparatus, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of certainly detecting the state that the output of an X-ray detection part becomes stable, and a computer program. <P>SOLUTION: The offset data caused by the heat noise in an X-ray detector 13 and a DAS unit 17 during the warming-up period after a power supply is put on are periodically collected in a definite period unit by the offset data collection part 321 of a console I/F unit 32 while the standard deviation SD is calculated with respect to the offset data collected in the definite period unit by a warming-up completion judging part 322 and the warming-up completion of the X-ray detector 13 and the DAS unit 17 is decided after the value of SD falls in a preset specification. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus having a warm-up function and a computer program.

  An X-ray CT apparatus, which is an X-ray diagnostic apparatus, arranges an X-ray tube and a multi-channel X-ray detector opposite to each other with the subject interposed therebetween, and these X-ray tube and X-ray detector are placed on the subject. While rotating around, the X-ray generated from the X-ray tube passes through the subject and is detected by the X-ray detector (for example, Patent Document 1).

  In this case, the multi-channel X-ray detector is connected to a data acquisition unit (hereinafter referred to as DAS (Data Acquisition System)) rotated together with these X-ray detectors, and the DAS as the X-ray detection unit is connected. / Configures the detector. These DAS / detectors have an integrator (C-AMP), an amplifier (P-AMP), and a digital converter (ADC) as DAS, and correspond to the X-ray intensity detected by the X-ray detector. The electrical signal (analog signal) is temporarily stored in an integrator (C-AMP). The stored electrical quantity is amplified by an amplifier (P-AMP) and then converted into a digital signal by a digital converter (ADC). Output as.

  By the way, such a DAS / detector has temperature characteristics due to changes in offset data (dark current) due to thermal noise, superiority and inferiority of the temperature and reality characteristics of the AMP IC constituting the amplifier.

  For this reason, in recent X-ray CT apparatuses, more precise temperature control and management is performed by increasing the definition of images, and when the apparatus is turned on, all DAS / detectors are first heated by heaters. The temperature is made uniform to start using the device. In this case, the DAS / detector heater is turned on immediately after the power is turned on, and the atmospheric temperature in the apparatus is measured by, for example, a temperature controller, and the atmospheric temperature in the apparatus is uniformly controlled, so that each X-ray detector can be controlled. And the temperature of the DAS is made uniform.

JP 2005-283441 A

  However, in such a method, the temperature of the DAS / detector can be controlled uniformly, but it cannot be determined whether the offset data due to the thermal noise of the DAS / detector is stable.

  In view of this, conventionally, the X-ray CT apparatus has been used after a warm-up period of about 2 hours after the power is turned on, but this warm-up period also varies greatly depending on the installation environment of the apparatus. .

  For this reason, the user cannot determine whether a stable image can be obtained by actually collecting data and generating an image, and when the patient was actually photographed first in the morning, the artifact was not sufficiently warmed up. In many cases, a picked-up image accompanied with a is obtained.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray CT apparatus and a computer program that can reliably detect a stable output of an X-ray detection unit.

To solve the above problem,
The invention according to claim 1 is an X-ray detection element for detecting X-rays transmitted through a subject, a multi-channel X-ray detection means each having a data collection unit for collecting detection data of the X-ray detection element, and a warm The offset data collecting means that periodically collects offset data corresponding to the multi-channel X-ray detection means during the up period and the offset data collected by the offset data collecting means in units of a fixed period. And determining means for determining a change in the state of a plurality of offset data corresponding to the X-ray detection means and determining the warm-up completion of the X-ray detection means based on the result.

  According to a second aspect of the present invention, in the first aspect of the invention, the determination unit uses a plurality of offset data corresponding to the same X-ray detection unit as a standard for determining the state change of the plurality of offset data. A deviation is obtained, and the completion of warm-up of the X-ray detection means is determined based on the standard deviation.

  According to a third aspect of the present invention, in the second aspect of the present invention, the determination means obtains a standard deviation for all offset data corresponding to the multi-channel X-ray detection means, and a standard for all the X-ray detection means. If the deviation value is within the standard value, the warm-up completion is determined.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, the determination unit obtains a standard deviation for predetermined offset data among offset data corresponding to the multi-channel X-ray detection unit, and determines the predetermined offset. It is characterized in that the warm-up completion is determined if the standard deviation value corresponding to the data is within the standard value.

  According to a fifth aspect of the present invention, in the second aspect of the invention, the determination unit divides the multi-channel X-ray detection unit into a plurality of regions, and calculates an average value of offset data corresponding to the plurality of regions. A standard deviation is obtained, and if the standard deviation values for all of the plurality of regions are within the standard value, the completion of warm-up is determined.

  According to a sixth aspect of the present invention, in the second aspect of the present invention, the determination unit obtains a standard deviation for predetermined offset data among offset data corresponding to the multi-channel X-ray detection unit, and these predetermined offsets are obtained. If the standard deviation value corresponding to the data is within the standard value, the standard deviation is obtained for all offset data corresponding to the multi-channel X-ray detection means, and the standard deviation values for all the X-ray detection means are obtained. It is characterized in that the warm-up completion is determined if it is within the standard value.

  The invention described in claim 7 includes multi-channel X-ray detection means each having an X-ray detection element for detecting X-rays transmitted through the subject and a data collection unit for collecting detection data of the X-ray detection element. A computer program for controlling an X-ray CT apparatus, wherein a first step of periodically collecting offset data corresponding to the multi-channel X-ray detection means during a warm-up period in units of a fixed period; Determining a state change of a plurality of offset data corresponding to the same X-ray detection means of the offset data collected in a unit of a predetermined period by the step, and determining completion of warm-up of the X-ray detection means based on the result A computer program comprising two steps.

  According to the present invention, it is possible to automatically detect a stable state of the output of the multi-channel X-ray detection means without any user operation. It can be obtained stably.

  Further, according to the present invention, since the output state of the multi-channel X-ray detection means is confirmed, it is possible to detect in advance an abnormality of the X-ray detection means before using the apparatus.

  Furthermore, according to the present invention, since the amount of calculation for obtaining the standard deviation for confirming the output state of the multi-channel X-ray detection means can be reduced, the processing capacity is low and relatively inexpensive as a data processing means such as a computer. Things can be used.

1 is a diagram showing a schematic configuration of an X-ray CT apparatus according to a first embodiment of the present invention. The figure which shows schematic structure of the rotation mount applied to 1st Embodiment. The figure which shows schematic structure of the X-ray detector applied to 1st Embodiment. The figure which shows schematic structure of the DAS / detector applied to 1st Embodiment. The flowchart explaining operation | movement of 1st Embodiment. The figure which shows schematic structure of the X-ray detector applied to the 2nd Embodiment of this invention. The figure which shows schematic structure of the X-ray detector applied to the 3rd Embodiment of this invention. The flowchart explaining operation | movement of 3rd Embodiment. The flowchart explaining operation | movement of the 4th Embodiment of this invention. The flowchart explaining operation | movement of the 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of an X-ray CT apparatus according to a first embodiment of the present invention.

  In this case, the X-ray CT apparatus includes a gantry device 10, a couch device 20, and a console unit 30. The gantry 10 includes a rotating gantry 11, and an X-ray source 12 and an X-ray detector 13 are arranged to face each other with the rotating gantry 11 interposed therebetween. Further, the gantry device 10 is provided with a high voltage generation unit 14, a gantry driving unit 15, an aperture driving unit 16, and a DAS unit 17.

  The rotary base 11 holds the X-ray source 12 and the X-ray detector 13, and is centered on a rotation axis located at the midpoint of a straight line connecting the X-ray source 12 and the X-ray detector 13 by the base drive unit 15. And rotated. The gantry driving unit 15 rotates the rotating gantry 11 based on the gantry control signal output by the control unit 31. The control unit 31 will be described later.

  The high voltage generator 14 supplies a high voltage according to the imaging conditions to the X-ray source 12 based on a control signal from the controller 31. In this case, the X-ray source 12 exposes an X-ray beam such as a fan shape or a cone shape by the high voltage supplied from the high voltage generator 14. The aperture drive unit 16 moves the X-ray shielding plate according to the imaging conditions, and adjusts the exposure range in the X-ray slice direction.

  The X-ray detector 13 detects an X-ray beam that has been exposed from the X-ray source 12 and transmitted through the subject P, and outputs a detection signal. In this case, the X-ray detector 13 is arranged to face the X-ray source 12 along the inner peripheral surface of the opening 11a of the rotary mount 11 as shown in FIG. X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb,... 13mn in which n channels (for example, 1000 channels) arranged in one row in the direction C are arranged in m slices in the slice direction S.

  A DAS unit 17 is connected to the X-ray detector 13. 4, the DAS unit 17 has DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn connected to X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb,. ing. In this case, the X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb,... 13mn, together with DAS 171a, 171b, ... 171n to 17ma, 17mb,. DAS / detectors 181a, 181b,... 181n to 18ma, 18mb,.

  DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn are an integrator that temporarily stores an electrical signal (analog signal) corresponding to the X-ray intensity detected by the X-ray detection element, It comprises an amplifier that amplifies the quantity, and a digital converter that converts the electric signal (analog signal) amplified by the amplifier into a digital signal and outputs it as image data. The amplifiers constituting DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn need to amplify a very small amount of electricity as offset data, and therefore it is desirable to use an amplifier having a large gain.

  The DAS unit 17 has a DAS controller 19. The DAS controller 19 collects and outputs data collected at DAS 171a, 171b,... 171n to 17ma, 17mb,.

  The couch device 20 has a couch top 21 on which the subject P is placed. The bed top 21 is supported by a bed base 22 having a bed driving unit 23.

  The couch driving unit 23 calculates the movement amount of the couch top 21 per rotation of the rotating gantry 11 based on the couch movement control signal output from the control unit 31, and the couch is calculated with the calculated movement amount at the time of scanning. The top plate 21 is moved. In this case, the bed top plate 21 is moved in the vertical direction by the bed driving unit 23 with the subject P placed thereon, and is movable in the body axis direction of the subject P.

  The console unit 30 has a control unit 31. The control unit 31 is connected to the above-described high voltage generation unit 14, gantry driving unit 15, aperture driving unit 16, DAS unit 17, and bed driving unit 23.

  In addition to the control unit 31, the console unit 30 includes a console I / F (interface) unit 32, a reconstruction processing unit 33, an image storage unit 34, an image processing unit 35, a display device 36, and an input unit 37. ing.

  The control unit 31 controls the entire apparatus. In this case, the control unit 31 outputs an X-ray beam generation control signal for controlling the X-ray beam generation to the high voltage generation unit 14, and instructs the gantry driving unit 15 to start diagnosis, and A gantry control signal for controlling the driving of the rotating gantry 11 is output. Further, the control unit 31 outputs a data acquisition control signal for controlling the data acquisition drive to the DAS unit 17, and outputs an aperture control signal for controlling the aperture of the X-ray beam to the aperture drive unit 16. . Then, a bed movement control signal for controlling the bed movement is output to the bed driving unit 23. The console I / F unit 32 receives transmission data from the DAS unit 17 that has collected the detection signals of the X-ray detector 13 by the gantry device 10. The console I / F unit 32 will be described later. The reconstruction processing unit 33 reconstructs an image for the subject P based on the collected data of the DAS unit 17 input via the console I / F unit 32 and outputs the image data. The image storage unit 34 temporarily stores the tomographic image data reconstructed by the reconstruction processing unit 33. The image processing unit 35 generates CT image data from the data stored in the image storage unit 34 and causes the display device 36 to display the CT image data. Then, the input unit 37 inputs various instructions for setting various imaging conditions and for failure diagnosis.

  The console I / F unit 32 includes an offset data collection unit 321 as an offset data collection unit and a warm-up completion determination unit 322 as a determination unit. The offset data collection unit 321 converts the offset data due to thermal noise at the DAS / detectors 181a, 181b,... 181n to 18ma, 18mb,. DAS 171a, 171b,... 171n to 17ma, 17mb,. In this case, offset data is collected periodically (for example, every minute) for 1 View (one projection image) for a certain period (for example, 10 minutes) during the warm-up period, and is obtained in units of a certain period, that is, Collect 10 View offset data. The warm-up completion determination unit 322 determines whether or not the warm-up can be completed every time offset data collection unit 321 collects offset data for a certain period, here 10 View. In this case, the warm-up completion determination unit 322 uses the 10 offset data of the same channel n in the same column m of the latest offset data state, here, 10 View worth of offset data for the latest 10 minutes, and the standard deviation SD. (Standard Deviation) is obtained, and if the SD value is within a preset standard value, it is determined that the warm-up of the corresponding DAS / detector is completed. Such a warm-up completion determination is performed for offset data from all m × n DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn, and these DAS 171a, 171b,. If the value of SD with respect to falls within a preset standard value, it is determined that warm-up has been completed for the corresponding DAS / detectors 181a, 181b,... 181n to 18ma, 18mb,. When such a warm-up completion determination is continuously obtained a predetermined number of times, the control unit 31 causes the display device 36 to display, for example, “SCAN READY” as a system notification.

  Next, the operation of the embodiment configured as described above will be described.

  Now, when the power of the X-ray CT apparatus is turned on, the chart shown in FIG. 5 is executed.

  In this case, the offset data is collected in a fixed state without rotating the rotary base 11 of the base apparatus 10. First, in step 501, the DAS / detector warm-up is started, and the X-ray beam is not exposed from the X-ray source 12 after the first minute, and in step 502, the DAS 171a, 171b,... 171n to 17ma, 17mb,. Next, in step 503, it is determined whether or not 10 View worth of offset data has been collected. If “No”, the process returns to step 502, and after the next one minute has elapsed, the offset data collecting unit 321 again. To collect offset data for 1 View from DAS 171a, 171b,... 171n to 17ma, 17mb,. After that, when 10 View offset data is collected in Step 503 and the result is Yes, the process proceeds to Step 504, and the warm-up completion determination unit 322 obtains the standard deviation SD. In this case, the warm-up completion determination unit 322 uses the 10 offset data of the same channel n in the same column m with respect to the offset data of 10 Views for 10 minutes (unit of a certain period) which is the latest offset data. Obtain the standard deviation SD. Specifically, if the m-column and n-channel offset data collected at time t is D (t, m, n), the standard deviation SD of the latest 10-minute offset data D is SD (m, n) = STD {D (t-9, m, n), D (t-8, m, n),... D (t, m, n)}. Here, STD is a function for calculating the standard deviation.

  In step 505, it is determined whether the SD value obtained in step 504 is within a preset standard value. If “No”, the process returns to step 502 to collect 10 View offset data in the next 10 minutes, and obtain a standard deviation SD for these offset data.

  Thereafter, if it is determined in step 505 that the SD value is within a preset standard value, it is determined that the warm-up is completed (step 506). Such determination of warm-up completion is performed for all offset data from m × n DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn, and these DAS 171a, 171b,. If the value of SD for is within a preset standard value, it is determined that the warm-up has been completed for all corresponding DAS / detectors 181a, 181b, ... 181n to 18ma, 18mb, ... 18mn. When such a warm-up completion determination is continuously obtained a predetermined number of times, the control unit 31 is notified of this, and “SCAN READY” is displayed as a system notification on the display device 36, for example. Let

  Such a warm-up completion determination may be provided with a time-up time, and a warning or error message may be displayed if the SD value does not fall within the specified value within the specified time. In addition, the state at this time may be left as a log so that it can be provided as auxiliary information for the subsequent trouble investigation of the service person.

  Therefore, in this way, offset data from DAS 171a, 171b,... 171n to 17ma, 17mb,. The standard deviation SD is obtained for a plurality of offset data of the same channel in the same column of offset data collected in units of these fixed periods, and the DAS is waited until these SD values are within a preset standard value. / The detector warm-up completion is judged. As a result, the output of DAS / detectors 181a, 181b,... 181n-18ma, 18mb,... 18mn corresponding to DAS 171a, 171b,. Compared with the conventional method of setting a warm-up period of about 2 hours based on experience and intuition, a high-definition image can be detected even immediately after power-up. It can be obtained stably. Also, since DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn are collected, and the output state of these DAS / detectors 181a, 181b,. Detecting abnormalities in DAS / detectors 181a, 181b, ... 181n-18ma, 18mb, ... 18mn corresponding to these DAS 171a, 171b, ... 171n to 17ma, 17mb, ... 17mn You can also.

(Second Embodiment)
In the first embodiment, the standard deviation SD is obtained for all the offset data from m × n DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn, but in this second embodiment, .. 171n to 17ma, 17mb,... 17mn out of the offset data from the DASs 171a, 171b,.

  In this case, as shown in FIG. 6, X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb in which n channels (for example, 1000 channels) arranged in one row in the channel direction C are arranged in m slices in the slice direction S. ,..., 13mn, for example, X-ray detection elements 131a, 131e, 131i,... 131n to 13ca, 13ce, 13ci,... 13cn to 13ma, 13me, 13mi. DAS 171a, 171e, 171i, ... 171n to 17ca, 17ce, 17ci, ... 17cn to 17ma, 17me, 17mi ... 17mn connected to the line detection element, the standard deviation SD in the same manner as the first embodiment. And determine the warm-up completion from this SD value. To.

  In this way, the same effect as that of the first embodiment can be obtained, and furthermore, the amount of calculation for obtaining the standard deviation SD can be drastically reduced. In addition to being obtained, data processing means such as a computer having a low processing capability and a relatively inexpensive one can be used.

(Third embodiment)
In the first embodiment, the standard deviation SD is obtained for all the offset data from the m × n DAS 171a, 171b,... 171n to 17ma, 17mb, ... 17mn, but in the third embodiment, DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn are divided into a plurality of parts, and the warm-up completion is determined based on the offset data obtained for each of the divided areas.

  In this case, as shown in FIG. 7, left X-ray detectors 131a, 131b,... 131n to 13ma, 13mb,... 13mn in which n channels arranged in one row in the channel direction C are arranged in m rows in the slice direction S are left. The region D1, the central region D2, and the right region D3 are divided into three regions corresponding to the X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb,... 13mn of the left region D1, the central region D2, and the right region D3. DAS 171a, 171b,... 171n to 17ma, 17mb,. The completion is determined.

  FIG. 8 illustrates the operation of the third embodiment. First, in step 801, DAS / detector warm-up is started, and after the first minute has elapsed, in step 802, offset data collection is performed. The unit 321 collects offset data for 1 view from the DASs 171a, 171b,... 171n to 17ma, 17mb, ... 17mn corresponding to the left region D1, the center region D2, and the right region D3. In step 803, the average value of the offset data is calculated for each of the left region D1, the central region D2, and the right region D3. Next, in step 804, it is determined whether or not 10 View worth of offset data has been collected. If NO in this case, the process returns to step 802, and after the next 1 minute has elapsed, the offset data collecting unit 321 causes the DAS 171a. , 171b,... 171n to 17ma, 17mb,..., And 17mn, offset data for 1 View corresponding to the left region D1, the center region D2, and the right region D3 are collected again. After that, when 10 View offset data is collected and the result is Yes in step 804, the process proceeds to step 805, and the warm-up completion determination unit 322 calculates the standard deviation SD. In this case, the warm-up completion determination unit 322 uses the average value of the offset data for each of the left region D1, the central region D2, and the right region D3 as the standard deviation using the 10-minute offset data for 10 minutes that is the latest offset data. Find SD.

  In step 806, it is determined whether the SD value obtained in step 805 is within a preset standard value. Here, if No, the process returns to step 802, and the average value of the offset data for the left area D1, the central area D2, and the right area D3 for 10 Views is collected in the next 10 minutes, and the standard deviation SD for these offset data is obtained. Ask. Thereafter, when it is determined in step 806 that the SD value is within a preset standard value, it is determined that the warm-up is completed (step 807). Such warm-up completion determination is performed for the left region D1, the central region D2, and the right region D3, and the SD values for the left region D1, the central region D2, and the right region D3 are within a preset standard value. Then, it is determined that the warm-up is completed for all corresponding DAS / detectors 181a, 181b,... 181n to 18ma, 18mb,. When such a warm-up completion determination is continuously obtained a predetermined number of times, this is notified to the control unit 31 and, for example, “SCAN READY” is displayed as a system notification on the display device 36. Let

  Therefore, even if it does in this way, the same effect as 1st Embodiment can be acquired, Furthermore, since the computational complexity for calculating | requiring the standard deviation SD can also be remarkably reduced in this case, warm-up completion is completed. A determination result can be obtained quickly, and a relatively inexpensive device with a low processing capability can be used as a data processing means such as a computer.

(Fourth embodiment)
In the first embodiment, offset data collection for 1 View is performed periodically (for example, for 1 minute) during a warm-up period for a certain period (for example, 10 minutes). In the embodiment, offset data for a plurality of views is collected periodically (for example, every minute), an average value of these offset data is obtained, and the standard deviation SD is calculated for these average values in the same manner as in the first embodiment. The warm-up completion is determined from the obtained SD value.

  FIG. 9 illustrates the operation of the fourth embodiment. First, in step 901, the DAS / detector warm-up is started. After the first minute has passed, in step 902, offset data collection is performed. The unit 321 collects offset data for a plurality of views from the DAS 171a, 171b,... 171n to 17ma, 17mb,. In step 903, the average value of the offset data of the same channel n is calculated in the same column m for the offset data for a plurality of views, and 1 view of offset data consisting of the average value is generated. In this case, if the offset data of m columns and n channels collected in PVview is D (p, m, n), the average value D (m, n) of the offset data is D (m, n). = AVE {D (p1, m, n), D (p2, m, n)... D (pn, m, n)}. Next, in Step 904, it is determined whether or not 1 View of offset data consisting of an average value has been collected for 10 Views. If No, the process returns to Step 902, and after the next 1 minute has passed, the offset is offset. The data collection unit 321 again collects offset data for a plurality of views from DAS 171a, 171b,... 171n to 17ma, 17mb,. After that, when 10 View offset data is collected and the result is Yes in Step 904, the process proceeds to Step 905, and the standard deviation SD is calculated by the warm-up completion determination unit 322. In this case, the warm-up completion determination unit 322 obtains the standard deviation SD using the 10-minute offset data for 10 minutes that is the latest offset data, that is, the View offset data including the average value for 10 View.

  In step 906, it is determined whether the SD value obtained in step 905 is within a preset standard value. Here, if No, the process returns to step 902, and in the next 10 minutes, 10 View worth of offset data consisting of an average value is collected, and a standard deviation SD for these offset data is obtained. Thereafter, if it is determined in step 906 that the SD value is within the preset standard value, it is determined that the warm-up is completed (step 907). Such determination of warm-up completion is performed for all offset data from m × n DAS 171a, 171b,... 171n to 17ma, 17mb,... 17mn, and these DAS 171a, 171b,. If the value of SD for is within a preset standard value, it is determined that the warm-up has been completed for all corresponding DAS / detectors 181a, 181b, ... 181n to 18ma, 18mb, ... 18mn. When such a warm-up completion determination is continuously obtained a predetermined number of times, this is notified to the control unit 31 and, for example, “SCAN READY” is displayed as a system notification on the display device 36. Let

  Therefore, even if it does in this way, the effect similar to 1st Embodiment can be acquired, Furthermore, the average value of the offset data for several View collected regularly is used as offset data for 1 View. Thus, the warm-up completion determination result with higher accuracy can be obtained from the calculation result of the standard deviation SD.

(Fifth embodiment)
In the second embodiment, the warm-up completion is determined from several representative offset data among the offset data from DAS 171a, 171b,... 171n to 17ma, 17mb,. In the embodiment, after determining the completion of warm-up from several representative offset data, the standard deviation of all offset data from m × n DAS 171a, 171b,... 171n to 17ma, 17mb,. SD is calculated.

  FIG. 10 illustrates the operation of the fifth embodiment. First, in step 1001, the DAS / detector warm-up is started, and after the first minute has elapsed, in step 1002, offset data collection is performed. The unit 321 collects offset data for 1 View from DAS 171a, 171b,... 171n to 17ma, 17mb,. Next, in step 1003, it is determined whether or not 10 View offset data has been collected. If NO in this step, the process returns to step 1002 and the DAS 171a, 171b,... 171n to 17ma, 17mb,... After that, when 10 View offset data is collected and the result is Yes in Step 1003, the process proceeds to Step 1004, and the standard deviation SD is obtained by the warm-up completion determination unit 322. In this case, the warm-up completion determination unit 322 includes, for example, the X-ray detection elements 131a, 131e, 131i, among the X-ray detection elements 131a, 131b,... 131n to 13ma, 13mb,. ... 131n to 13ca, 13ce, 13ci,... 13cn to 13ma, 13me, 13mi... 13mn, etc. are set as representative points, and DASs 171a, 171e, 171i,. The standard deviation SD is obtained for the offset data from 17ce, 17ci,... 17cn to 17ma, 17me, 17mi ... 17mn in the same manner as in the first embodiment. In step 1005, it is determined whether the SD value at this time is within a preset standard value. If “No”, the process returns to step 1002 to collect 10 View offset data in the next 10 minutes, and the above-described operation is repeated. On the other hand, if it is determined in step 1005 that the value of SD is within the preset standard value, the process proceeds to step 1006, and this time, from m × n DAS 171a, 171b,. The standard deviation SD is obtained for the offset data in the same manner as in the first embodiment, and in step 1007, it is determined again whether the value of SD is within a preset standard value. If “No”, the process returns to step 1002 to collect 10 View offset data in the next 10 minutes, and the above-described operation is repeated. On the other hand, if it is determined in step 1007 that the SD value is within the preset standard value, it is determined that the warm-up has been completed for DAS / detectors 181a, 181b, ... 181n to 18ma, 18mb, ... 18mn ( Step 1008). When such a warm-up completion determination is continuously obtained a predetermined number of times, the control unit 31 is notified of this, and the display device 36 displays “SCAN READY” as a system notification.

  Therefore, even if it does in this way, the effect similar to 1st Embodiment can be acquired, Furthermore, since the calculation amount for calculating | requiring the standard deviation SD can be made small also in this case, the determination result of warm-up completion is obtained. It can be obtained quickly and a data processing means such as a computer having a low processing capability and a relatively inexpensive one can be used.

  In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change variously in the range which does not change the summary. For example, in the above-described embodiment, the offset data is collected while the rotating gantry 11 of the gantry device 10 is fixed without rotating, but may be performed while the rotating gantry 11 is rotated. . When offset data is collected while rotating the rotating gantry 11 in this way, the air in the rotating gantry 11 is agitated and homogenized, and more accurate temperature adjustment and determination of warm-up completion can be realized.

  Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. If the above effect is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

DESCRIPTION OF SYMBOLS 10 ... Mount apparatus, 11 ... Rotary mount, 12 ... X-ray source, 13 ... X-ray detector,
131a, 131b,... 131n to 13ma, 13mb,... 13mn ... X-ray detection element 14 ... high voltage generator, 15 ... gantry drive unit, 16 ... aperture drive unit, 17 ... DAS units 171a, 171b, ... 17mb ... 17mn ... DAS
181a, 181b, ... 181n to 18ma, 18mb, ... 18mn ... DAS / detector 19 ... DAS controller, 20 ... couch device 21 ... couch top plate, 22 ... couch base, 23 ... couch drive unit 30 ... console unit, 31 ... Control unit, 32 ... Console I / F unit 321 ... Offset data collection unit, 322 ... Warm-up completion determination unit 33 ... Reconstruction processing unit, 34 ... Image storage unit, 35 ... Image processing unit 36 ... Display device, 37 ... Input section

Claims (7)

Multi-channel X-ray detection means each having an X-ray detection element for detecting X-rays transmitted through the subject and a data collection unit for collecting detection data of the X-ray detection element;
Offset data collection means for periodically collecting offset data corresponding to the multi-channel X-ray detection means during the warm-up period in units of a fixed period;
A change in the state of a plurality of offset data corresponding to the same X-ray detection means of the offset data collected by the offset data collection means in units of a fixed period is determined, and the warm-up completion of the X-ray detection means is determined based on this result Determining means for determining;
An X-ray CT apparatus comprising: The determination means obtains a standard deviation by using a plurality of offset data corresponding to the same X-ray detection means to determine a state change of the plurality of offset data, and based on the standard deviation, the X-ray detection means The X-ray CT apparatus according to claim 1, wherein warm-up completion is determined. The determination means obtains standard deviations for all offset data corresponding to the multi-channel X-ray detection means, and determines the completion of warm-up if the standard deviation values for all the X-ray detection means are within the standard values. The X-ray CT apparatus according to claim 2. The determination means obtains a standard deviation for predetermined offset data among the offset data corresponding to the multi-channel X-ray detection means, and warms if the standard deviation value corresponding to the predetermined offset data is within the standard value. The X-ray CT apparatus according to claim 2, wherein completion of the up is determined. The determination means divides the multi-channel X-ray detection means into a plurality of areas, obtains a standard deviation for an average value of offset data corresponding to the plurality of areas, and values of standard deviations for all the plurality of areas are obtained. The X-ray CT apparatus according to claim 2, wherein the warm-up completion is determined if it is within a standard value. The determination means obtains a standard deviation for predetermined offset data among the offset data corresponding to the multi-channel X-ray detection means, and if the standard deviation value corresponding to the predetermined offset data is within the standard value, Further, a standard deviation is obtained for all offset data corresponding to the multi-channel X-ray detection means, and if the standard deviation values for all the X-ray detection means are within a standard value, completion of warm-up is determined. The X-ray CT apparatus according to claim 2. A computer for controlling an X-ray CT apparatus provided with a multi-channel X-ray detection means each having an X-ray detection element for detecting X-rays transmitted through a subject and a data collection unit for collecting detection data of the X-ray detection element A program,
A first step of periodically collecting offset data corresponding to the multi-channel X-ray detection means during a warm-up period in units of a fixed period;
A change in the state of a plurality of offset data corresponding to the same X-ray detection means of the offset data collected in a fixed period unit by the first step is determined, and the warm-up completion of the X-ray detection means is determined based on the result. A computer program comprising: a second step of determining.

Images