JP2014147822A - X-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically detect an image failure to prevent missing of detection of the failure when the failure occurs, and enable easy and prompt scanning limited to a range where re-scanning is required.SOLUTION: An X-ray CT apparatus of a helical-scan system 1 has: a cradle side control unit 37 for preparing extra data including output values of tube voltage and tube current of X-ray with which an analyte P is irradiated and a top board position of a bed device 2, and associating this extra data with collection data on each view; a scanning control unit 41 for determining whether the output values of tube voltage and current included in the extra data coincide with predetermined tube voltage and current set in a scanning plan, or preset values of tube voltage and current, reading the top board position from the extra data including the output values of tube voltage and current not coinciding with the preset values and setting a sum to be an error range on the basis of the read top board position; and a pre-processing unit 43.

Description

  The present invention relates to an X-ray CT apparatus, and more particularly to a helical scan type X-ray CT apparatus.

  In recent years, a couch device that controls the position of a top plate that sends a subject to an X-ray irradiation field and enables continuous X-ray irradiation over a specified scan range set in a scan plan, and obtained transmission A helical scan type X-ray CT apparatus that collects X-ray attenuation rates as collected data and constructs an arbitrary tomographic image based on a continuous attenuation rate distribution in a scan range has been proposed (see Patent Document 1).

  "Scanning plan" defines various scanning conditions such as slice thickness, tube voltage and current, and X-ray intensity control conditions (modulation conditions), in addition to the scan range of the subject established based on scanograms, etc. Thus, it is prepared as a control program for the X-ray CT apparatus.

  The helical scan method has a higher scanning speed than the non-helical scan method (multi-scan method or the like), and greatly contributes to the reduction of the contrast agent and the enhancement of the contrast effect. In addition, the helical scan method can form an image from any continuous scan position without any breaks, and makes it possible to grasp the continuity of a tomographic image or a complex three-dimensional structure.

JP 2009-160270 A

  Occasionally, a vast amount of image data generated by the X-ray CT apparatus includes defective image data, and the displayed tomographic image may become unclear. The problem of image failure is a problem of image reliability, which leads to a diagnosis based on image observation and a reduction in quality of three-dimensional stereoscopic image display.

  In the helical scan that takes advantage of the high speed and continuity of the scan, the scan is continued even if the image data is partially defective. Therefore, when an image defect is noticed, it is necessary to scan again. In particular, it is necessary to avoid overlooking image defects such as being used for diagnosis without noticing image defects.

  Conventionally, when recognizing an image defect and redoing a scan, it is based on an empirical decision to check the acquired tomographic images one by one, or extra data added to the collected data on which the image data is based (accompanying information) Error occurrence (for example, the intensity and energy of irradiated X-rays, the focus position and focus size of the X-ray generator tube are abnormal, the occurrence of transmission errors in collected data), and the error occurrence range (the position of the couch top) ) And the like are checked to identify the necessary scan range. This work avoids unnecessary X-ray exposure of the subject by re-scanning the entire scan range, but in addition to reducing the accuracy of the scan range due to human error, it takes a lot of time and effort. It is necessary, and it is also a factor that decreases the throughput.

  The present invention has been made in view of the above circumstances, and when an image defect occurs, the image defect is automatically detected and can be prevented from being overlooked, and scanning limited to a scan range that needs to be redone is easy. An object of the present invention is to provide an X-ray CT apparatus that can be executed quickly and quickly.

  In order to achieve the above-described object, the bed apparatus that controls the position of the top plate that sends the subject to the X-ray irradiation field and enables continuous X-ray irradiation within a predetermined scan range set in the scan plan. In a helical scan X-ray CT apparatus that collects the obtained transmission X-ray attenuation rate as collected data and constructs an arbitrary tomographic image based on a continuous attenuation rate distribution in the scan range, irradiates the subject The X-ray characteristics of the X-rays and the couch position of the bed apparatus are used as extra data, and the data generation unit corresponding to the collected data of each view and the X-ray characteristics included in the extra data are used in the scan plan. Judges whether or not it matches the preset X-ray characteristics, reads the top board position from the extra data including X-ray characteristics that do not match the default X-ray characteristics, and reads And characterized in that it comprises an error range specifying section for specifying the error range based on the top position.

  Alternatively, the position of the top plate that sends the subject to the X-ray irradiation field is controlled, and a bed device that enables continuous X-ray irradiation within a predetermined scan range set in the scan plan is provided, and the obtained transmission is provided. In a helical scan X-ray CT system that collects X-ray attenuation rates as collected data and constructs an arbitrary tomographic image based on a continuous attenuation rate distribution in the scan range, it is determined whether transmission errors have occurred in the acquired data Then, an error flag indicating that a transmission error has occurred and the couch position of the bed apparatus are used as extra data, and a data generation unit that associates the extra data with the collected data of each view, and the extra data includes an error flag. The top plate position is read from the extra data including the error flag, and an error is determined based on the top plate position. Characterized in that it comprises an error range specifying section for specifying a range.

  According to the present invention, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and a scan limited to a scan range that needs to be redone can be performed easily and quickly.

1 is a functional block diagram showing a first embodiment of an X-ray CT apparatus according to the present invention. The figure which shows the structure of the collection data extra data produced | generated in the gantry side control part of FIG. 1, FIG. 2 (A) is a figure which shows the whole structure, FIG. 2 (B) is a figure which shows extra data. Explanatory drawing of the display process of the error range performed with the X-ray CT apparatus of FIG. The functional block diagram which shows 2nd Embodiment of the X-ray CT apparatus which concerns on this invention. The functional block diagram which shows 3rd Embodiment of the X-ray CT apparatus which concerns on this invention. Explanatory drawing of the display process of the error range performed with the X-ray CT apparatus of FIG.

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

(First embodiment)
FIG. 1 is a functional block diagram showing a first embodiment of an X-ray CT apparatus according to the present invention.

  As shown in FIG. 1, the X-ray CT apparatus 1 of the present embodiment includes a bed apparatus 2, a rotary mount 3, and a console 4.

[Bed equipment]
The bed apparatus 2 is configured so that the subject P is sent to the rotary base 3 serving as an X-ray irradiation field, and continuous X-ray irradiation can be performed on a predetermined scan range set in the scan plan.

  The top plate 21 can be slid with the subject P placed thereon, and the top plate driving device 22 slides the top plate 21 steplessly.

[Rotating base]
The rotating gantry 3 is configured to irradiate the subject P with X-rays and collect a continuous attenuation rate distribution of transmitted X-rays for a predetermined scan range set in the scan plan.

  The subject insertion passage 31 is capable of inserting the subject P placed on the top 21 and serves as an X-ray irradiation field for the subject P. A gantry driving device 32, an X-ray generator tube 33, an X-ray detector 34, a high voltage generator (X-ray generator) 35, a DAS (Data Acquisition System) 36, and the gantry side so as to surround the subject insertion passage 31 A control unit 37 is provided.

  The gantry driving device 32 is configured to be rotatable while holding the X-ray generation tube 33 and the X-ray detector 34 facing each other, and the X-ray generation tube 33 and the X-ray detector 34 having the subject insertion path 31 as a rotational center. Enables 360 ° turn.

  The X-ray generator tube 33 is supplied with a required tube voltage and tube current from the high voltage generator 35, and generates an X-ray fan beam from an arbitrary rotation position of 360 ° with an intensity and energy corresponding to the tube voltage and tube current. The target P is irradiated with X-rays.

  The X-ray detector 34 is configured as an X-ray detection element array in which a plurality of X-ray detection elements are two-dimensionally arranged in the body axis direction (axial direction) of the subject P and the body axis orthogonal direction (channel direction). . The X-ray detector 34 transmits transmitted X-rays that pass through the subject P that is radiated from the X-ray generation tube 33 that rotates around the subject insertion passage 31 and moves in the subject insertion passage 31, that is, the subject. The transmitted X-rays that have passed through the P helical trajectory are detected by each X-ray detection element, and an electrical signal corresponding to the attenuation rate (absorption rate) of the transmitted X-rays is output.

  The DAS 36 collects electrical signals output from the X-ray detection elements of the X-ray detector 34, performs integration (sample hold) for a predetermined time, AD converts the integration value, and converts the integration value into the body included in the subject P. Collected data in digital format reflecting the attenuation rate of X-rays by the tissue is generated.

  The gantry-side control unit 37 controls the tube voltage and tube current that determine the energy and intensity of the X-rays output from the high voltage generator 35 and radiated from the X-ray generator tube 33. The gantry-side control unit 37 uses the tube voltage and tube current output from the high voltage generator 35 (the tube voltage and tube current applied to the X-ray generation tube 33) as the X-ray characteristic tube voltage and tube current output values. Receive as.

  Further, the gantry-side control unit 37 outputs an X-ray timing signal that triggers the output and stop of tube voltage and tube current by the high voltage generator 35 (X-ray emission of the X-ray generator tube 33 and its stop), Also, a sample hold signal for controlling the sample hold time by the DAS 36 is generated.

  Further, the gantry-side control unit 37 receives the collected data output from the DAS 36 through the generation of the X-ray timing signal and the sample hold signal. The gantry-side control unit 37 adds the extra data (accompanying information) to the received collected data to generate collected data / extra data, and transmits the collected data / extra data to the console 4.

  FIG. 2 is a diagram showing the structure of collected data / extra data generated by the gantry-side control unit 37, FIG. 2 (A) is a diagram showing the overall structure, and FIG. 2 (B) is a diagram showing extra data. .

  Collected data / extra data (FIG. 2A) is one scan (hereinafter referred to as “X-ray irradiation position (position of the top plate 21)” and X-ray irradiation direction (position of the X-ray generation tube 33) of the subject P. , View), and the number of Views is generated.

  As shown in FIG. 2B, the extra data included in each collected data / extra data includes collected data such as “X-ray status”, “data transmission status”, “bed status”, and “table status”. It has information indicating the generation conditions.

  The X-ray status, which is one of the extra data, affects the image quality of the scanned image, such as the output values of the tube voltage and tube current received from the high voltage generator 35, the focus position and the focus size of the X-ray generator tube 33. Various conditions (X-ray characteristics) are recorded.

  In addition, an error flag indicating a transmission error of collected data / extra data is recorded in the data transfer status, and a position of the top board 21 and a moving speed thereof are recorded in the bed status. In addition, in the gantry status, a rotating part of the gantry driving device 32 that rotates the X-ray generation tube 33, a rotation speed and a rotation position of the X-ray generation tube 33, and the like are recorded.

  In addition, when sending the collected data / extra data to the console 4, the gantry-side control unit 37 adds a CRC (Cyclic Redundancy Check) code for checking whether there is a data transmission error for the collected data / extra data of each view. To do.

  The gantry-side control unit 37 collectively collects the collected data / extra data of a plurality of views according to the data transmission protocol, and transmits the collected data / extra data to the console 4 in packet units.

[console]
The console 4 controls the couch device 2 and the rotating gantry 3 and constructs a tomographic image of the subject P based on the continuous attenuation rate distribution of the scan range generated by the cooperation of the couch device 2 and the rotating gantry 3. And configured to display.

  In addition to the scan range of the subject P that is formulated based on a scanogram, the scan control unit 41 determines the slice thickness, the number of effective columns of the X-ray detection element array for each view, the tube voltage / tube current, and the X for each view. A scan plan (scan condition) such as a line intensity control condition (modulation condition) is held as a control program for the X-ray CT apparatus 1.

  The scan control unit 41 controls the top plate driving device 22, the gantry driving device 32, and the gantry side control unit 37 according to the scan plan, controls the position of the top plate 21, controls the rotation of the X-ray generation tube 33, and the gantry side control unit. The overall control of the helical scan is performed by setting the generation timing of 37 X-ray timing signals and sample hold signals.

  During execution of the helical scan controlled by the scan control unit 41, the interface unit 42 receives the collected data / extra data of each view generated on the rotating gantry 3 side and transmits it to the preprocessing unit 43.

  This interface unit 42 determines whether or not there is a transmission error for the collected data / extra data of each view based on the CRC code added by the gantry-side control unit 37 before transmitting the collected data / extra data to the pre-processing unit 43. I do.

  When it is determined that a transmission error has occurred in any of the collected data / extra data, the interface unit 42 records an error flag in the data transmission status of the collected data / extra data related to the transmission error.

  The preprocessing unit 43 performs calibration and sensitivity correction on the collected data included in the View collected data / extra data received from the interface unit 42 as preprocessing of the reconstruction processing executed by the reconstruction processing unit 44. Then, processing such as logarithmic conversion (Radon conversion) of the X-ray attenuation rate is performed to generate so-called projection data (raw data).

  The reconstruction processing unit 44 performs a reconstruction process based on the Fourier transform method or the filtered back projection method on the projection data generated by the preprocessing unit 43 to calculate an X-ray attenuation rate distribution (CT value distribution), Image data to be a tomographic image of the subject P is generated based on the X-ray attenuation rate distribution. The image data is stored in the storage unit 45.

  The image processing unit 46 generates various scan images such as a tomographic image and a three-dimensional stereoscopic image based on the image data stored in the storage unit 45. The input device 47 includes an operation device such as a keyboard and a mouse for instructing the image processing unit 46 on display conditions desired by the user, such as image contrast and a region of interest (Region of Interest). The scan image generated by the processing unit 46 is displayed according to the specified display condition.

  The scan control unit 41, the preprocessing unit 43, and the image processing unit 46 of the X-ray CT apparatus 1 cooperate to execute a scan plan resetting process and an error range display process. Hereinafter, steps in each process will be described.

[Scan range reset processing]
The scan plan resetting process is executed when the collection data group of all the views, which is the basic data of the image data, includes abnormal collection data. In other words, a process for automatically setting a scan plan related to the scan re-execution. It is.

(Step 101)
The pre-processing unit 43 uses the X-rays actually irradiated on the subject P in each view based on the output values of the tube voltage and tube current recorded in the collected data and extra data of each view received from the interface unit 42. Determines whether the tube voltage and tube current are normal or abnormal.

  As a start process of this determination, the pre-processing unit 43 sets the set values (planned values) of the tube voltage and the tube current of each View that will follow the path of the scan control unit 41 → the gantry side control unit 37 → the high voltage generator 35. ) Is received directly from the scan control unit 41 each time the set value is generated.

(Step 102)
The pre-processing unit 43 sets the tube voltage and tube current setting values of the view received from the scan control unit 41, and the tube voltage and tube current recorded in the collected data / extra data of each view received from the interface unit 42. It is determined whether the output value matches or does not match.

(Step 103)
When determining that the set values of the tube voltage and tube current and the output values of the tube voltage and tube current do not match, the preprocessing unit 43 calculates a difference between the set value and the output value. If it is determined that the set value matches the output value, the process does not proceed to the following step.

(Step 104)
A threshold is determined for the difference between the tube voltage and tube current output value and the set value of the tube voltage and tube current, and a high voltage is generated for a view where the difference between the tube voltage and tube current output value and the set value exceeds the threshold value. It is determined that the output values of the tube voltage and tube current output by the apparatus 35, that is, the intensity and energy of the irradiated X-rays irradiated to the subject P are abnormal.

(Step 105)
When the preprocessing unit 43 determines that the output values of the tube voltage and the tube current are abnormal, the preprocessing unit 43 reads the data on the top position recorded in the collected data / extra data of the View corresponding to the determination result. Then, the preprocessing unit 43 sends the read data of the top board position to the scan control unit 41.

(Step 106)
The scan control unit 41 cumulatively collects and adds the top plate positions, and the position of the top plate 21 at the time when the output values of the tube voltage and the tube current are abnormal and immediately before the abnormality is resolved. The position of the top plate 21 is specified. Then, the scan control unit 41 sets the movement range of the top plate 21 determined by the two specified positions of the top plate 21 as an error range.

(Step 107)
The scan control unit 41 uses the stored current scan plan as it is for other conditions excluding the scan range, and for the scan range, substitutes the error range specified in step 106 as “Redo”. It is generated and memorized as “scan plan”.

  When the X-ray CT apparatus 1 executes another scan based on the “redo scan plan”, it is conditional on having received an operator scan start request.

[Error range display processing]
The error range display process is a process of displaying the error range on the screen of the display device 48 based on the result of the scan image resetting process.

(Step 201)
The scan control unit 41 sends the top position data received from the preprocessing unit 43 to the image processing unit 46.

(Step 202)
The image processing unit 46 specifies the error range based on processing similar to Step 106 and Step 107 executed by the scan control unit 41 using the data on the top position received from the preprocessing unit 43.

(Step 203)
The image processing unit 46 displays the error range specified in step 202 on the display device 48. At this time, as shown in FIG. 3, the image processing unit 46 displays the error range so as to overlap the scanogram image acquired in advance and stored in the storage unit 45 in order to set the scan range.

  Next, the effect will be described.

In the X-ray CT apparatus 1,
(1) The X-ray tube voltage and tube current output values (X-ray characteristics) irradiated to the subject P and the couch position of the couch device 2 are used as extra data, and this extra data corresponds to the collected data of each view. A gantry-side control unit 37 that generates collected data and extra data is provided. Also, whether the tube voltage and tube current output values included in the collected data and extra data match the default tube voltage and tube current set in the scan plan, i.e., whether the tube voltage and tube current are set. A scan control unit 41 and a pre-processing unit 43 that determine and read the top plate position from the collected data / extra data including the output values of the tube voltage and the tube current that do not match and set the total of the read top plate positions as an error range are provided. .

  For this reason, when the high voltage generator 35 is temporarily discharged during the execution of the helical scan and the required tube voltage and tube current set in the scan plan are not applied to the X-ray generator tube 33, this problem is caused. Is automatically detected. That is, an abnormality in collected data accompanying discharge or an image defect based on this is automatically detected. Therefore, since no human error is involved in detecting an image defect, the reliability of the image defect detection is extremely good.

  In addition, the scan control unit 41 is configured to replace the default scan range set in the scan plan with the error range specified by the scan control unit 41 and the pre-processing unit 43 and to make a rescan plan. Therefore, in addition to automatically specifying an error range in which an image defect has occurred and it is necessary to perform scanning again, a scan plan limited to the specified error range is automatically created. Then, when there is a scan start request from the operator (the operator only makes a scan start request), a “redo scan plan” limited to the error range is executed.

  In short, according to the X-ray CT apparatus 1, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and the scan limited to the scan range that needs to be redone can be easily performed. Can be executed quickly.

  (2) An image processing unit 46 that displays the specified error range superimposed on the scanogram image of the subject P including the predetermined scan range set in the scan plan is provided. For this reason, in the case where the scan re-execution is executed on the condition that the operator requested to start the scan, the operator can easily determine whether the scan re-execution is necessary. For example, even if the tomographic image displayed on the display device 48 is unclear, when such an image defect is out of the region of interest, there is no need to repeat the scan. According to the X-ray CT apparatus 1, such a determination becomes easy.

(Second Embodiment)
FIG. 4 is a functional block diagram showing a second embodiment of the X-ray CT apparatus according to the present invention.

  The present embodiment is an example in which the configurations of the preprocessing unit 43 and the scan control unit 41 in the X-ray CT apparatus 1 of the first embodiment are changed. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol, description is abbreviate | omitted, and the structure which changed the structure of 1st Embodiment, or was newly added attaches | subjects "A" to the code | symbol end, and demonstrates it .

  As shown in FIG. 4, the X-ray CT apparatus 1A of the present embodiment includes a scan control unit 41A and a preprocessing unit 43A.

  The scan control unit 41A and the preprocessing unit 43A cooperate to execute a scan plan resetting process based on the presence / absence determination of an error flag. Hereinafter, each step in the scan plan resetting process will be described.

(Step 301)
When the preprocessing unit 43A receives the collected data / extra data from the interface unit 42, the preprocessing unit 43A indicates the presence / absence of an error flag recorded in the data transmission status of the collected data / extra data of each view, that is, a data transmission error. Determine the presence or absence of information.

(Step 302)
When determining that the error flag is recorded, the pre-processing unit 43A reads the data on the “top position” recorded in the bed status of the collected data / extra data of the View in which the error flag is recorded. Then, the preprocessing unit 43A sends the read data of the top board position to the scan control unit 41A.

(Step 303)
The scan control unit 41A collects the data of the top board position received from the preprocessing unit 43A, and the position of the top board 21 at the time when the data transmission error occurs and the top board 21 immediately before the data transmission error is eliminated. Identify the location. Then, the scan control unit 41A sets the error range as the movement range of the top plate 21 determined by the two specified positions of the top plate 21.

(Step 304)
As in the first embodiment, the scan control unit 41A uses the other conditions excluding the scan range in the stored current scan plan as they are, and the error specified in step 303 for the scan range. A “redo scan plan” is generated and stored using the range. The other processes in the scan range resetting process and the error range display process are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, the effect will be described.

In the X-ray CT apparatus 1A,
(3) It is determined whether or not a transmission error has occurred in the collected data, and an error flag indicating that a transmission error has occurred and the table top position of the bed apparatus 2 are used as extra data, and this extra data is associated with the collected data of each view. In addition, a gantry-side control unit 37 and an interface unit 42 that generate collected data and extra data are provided. Also, it is determined whether or not an error flag is included in the collected data / extra data, scan position is read from the collected data / extra data including the error flag, and the total of the top position is the error range. 41A and the pre-processing part 43A are provided.

  For this reason, when a transmission error of collected data occurs, this transmission error is automatically detected. That is, an image defect based on a transmission error is automatically detected. Accordingly, since no human error is involved in detecting an image defect, the reliability of the image defect detection is extremely high.

  In addition, the scan control unit 41A is configured to replace the default scan range set in the scan plan with the error range specified by the scan control unit 41A and the pre-processing unit 43A, thereby forming a rescan plan. Therefore, in addition to automatically specifying an error range in which an image defect has occurred and it is necessary to perform scanning again, a scan plan limited to the specified error range is automatically created. Then, when there is a scan start request from the operator (the operator only makes a scan start request), a second scan limited to the error range is executed.

  In short, according to the X-ray CT apparatus 1A, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and the scan limited to the scan range that needs to be redone can be easily performed. Can be executed quickly.

(Third embodiment)
FIG. 5 is a functional block diagram showing a third embodiment of the X-ray CT apparatus according to the present invention.

  The present embodiment is an example in which the configurations of the scan control unit 41 and the image processing unit 46 in the X-ray CT apparatus 1 of the first embodiment are changed. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol, abbreviate | omits description, The structure which changed the structure of 1st Embodiment or added newly is attached | subjected with a code | symbol "B", and is demonstrated. .

  As shown in FIG. 5, the X-ray CT apparatus 1B of the present embodiment includes a scan control unit 41B and an image processing unit 46B.

  The scan control unit 41B and the image processing unit 46B cooperate to execute scan plan resetting processing and division error range display processing performed by dividing the error range. Hereinafter, each step in the scan plan resetting process will be described.

(Step 401)
The scan control unit 41B determines whether the error range identified in step 107 is continuous along the body axis direction of the subject P following the processing of step 101 to step 107 in the scan range resetting process of the first embodiment. Or it determines whether it is not continuous (it distributes discretely). That is, it is determined whether or not a normal range that is not an error range is included between the error range specified in step 107 and the error range.

  When the scan control unit 41B determines that the error range is distributed discretely, each error range in the discrete distribution form excluding the normal range is set as a divided error range.

(Step 402)
Similarly to the first embodiment, the scan control unit 41B uses other conditions excluding the scan range in the stored current scan plan as they are, and the scan range specified in step 401 is divided. A substitute for the error range is generated and stored as a redo scan plan.

[Division error range display processing]
The error range display process is a process of displaying the division error range on the screen of the display device 48 based on the result of the scan image resetting process.

(Step 501)
The scan control unit 41B sends the top position data received from the preprocessing unit 43 to the image processing unit 46B.

(Step 502)
The image processing unit 46B uses the top position data received from the scan control unit 41B, and based on the processing similar to the processing in step 106 and step 107 in the scan range resetting processing of the first embodiment, the error range. Is identified.

(Step 503)
The image processing unit 46B determines that the error range specified in step 502 is continuous along the body axis direction of the subject P based on the same processing as the processing in step 401 executed by the scan control unit 41B. Determine if it is not continuous.

  When the image processing unit 46B determines that the error ranges are distributed in a discrete manner, each error range in the discrete distribution form excluding the normal range is set as a divided error range.

(Step 504)
The image processing unit 46B displays the specified division error range on the display device 48. At this time, as shown in FIG. 6, the image processing unit 46 </ b> B displays the division error range so as to overlap the scanogram image acquired in advance and stored in the storage unit 45 in order to set the scan range.

  Next, the effect will be described.

In the X-ray CT apparatus 1B, in addition to the effects (1) and (2) of the first embodiment, the following effects can be obtained.
(4) It is determined whether a normal range that is not an error range is included between the error range and the error range. If it is determined that such a normal range is included, the portion excluding the normal range is A scan control unit 41B and a preprocessing unit 43B are provided as division error ranges.

  For this reason, even when the scan re-execution is executed without the operator's scan start request as a condition, it is possible to avoid the scan re-execution including the normal range. That is, in the first embodiment, even if the region of interest is located between the error ranges and a good image is obtained for the region of interest, the first error range starts from the start position. There is a possibility that another scan may be executed in the range up to the end position of the next error range. According to the X-ray CT apparatus 1B of the present embodiment, even if the error range is distributed at intervals, it is possible to rescan the pinpoint only for the scan range related to the image defect, and the subject P is wasted. Exposure can be avoided.

  (5) An image processing unit 46B that displays the specified division error range superimposed on the scanogram image of the subject P including the predetermined scan range set in the scan plan is provided. For this reason, in the case where the scan re-execution is executed on the condition that the operator requested to start the scan, the operator can easily determine whether the scan re-execution is necessary, as in the effect (2) of the first embodiment.

  The X-ray CT apparatus according to the present invention has been described based on one of the first to third embodiments, but the specific configuration is not limited to these embodiments, and Design changes and additions are permitted without departing from the scope of the invention described in the scope.

  In the first embodiment, an example in which X-ray characteristics of tube voltage and tube current output values output from the high voltage generator 35 are used as an index for specifying an error range (a scan range in which an image is defective). However, since the X-ray characteristics used for specifying the error range are selected as X-ray conditions that affect the image quality of the scanned image, instead of the output values of the tube voltage and tube current, The X-ray focal position or the X-ray focal spot size may be used.

  Further, as the X-ray characteristics, both the tube voltage output value and the tube current output value may be used, and either the tube voltage output value or the tube current output value may be used.

  Further, when the specified error range is narrower than the predetermined width in the process of step 107 in the scan range resetting process (for example, when an X-ray characteristic abnormality occurs in one view), the error range is You may make it expand an error range so that it may become more than predetermined width. If the displayed tomographic image is too narrow, it cannot be used for diagnosis, but the significance of re-scanning can be ensured by expanding the error range. For the same purpose, the threshold value may be determined for the width of the error range, and if the error range is extremely narrow and does not satisfy the predetermined width, the scan may not be performed again.

  Further, the X-ray CT apparatus 1 is an example on the condition that a scan start request from the operator is received when performing another scan based on the “redo scan plan”. However, the scan start request from the operator is not a condition, and a redo scan may be automatically executed when a preset image defect occurs in a preset scan range (for example, a region of interest). Good.

  Further, in the process of step 202 in the error range display process, the image processing unit 46 specifies an error range based on the same process as the step 106 and step 107 executed by the scan control unit 41. . However, the image processing unit 46 may use the error range specified in the process of step 107 without specifying the error range.

  The gantry-side control unit 37 adds an CRC code for checking whether there is a data transmission error to the collected data / extra data of each view when transmitting the collected data / extra data to the console 4. Since the CRC code is added to check whether there is a transmission error for the collected data, any other code that allows such a check can be used instead of the CRC code.

  Further, although the gantry side control unit 37 functions as a data generation unit, the function of the data generation unit may be given to a different part from the gantry side control unit 37.

  Further, although the scan control unit 41 and the preprocessing unit 43 function as a data range specifying unit, the function of the data range specifying unit may be given to a different part from the scan control unit 41 and the preprocessing unit 43.

  The scan control unit 41 functions as a scan plan resetting unit, but the function of the scan plan resetting unit may be given to a different part from the scan control unit 41.

  The image processing unit 46 functions as an error range display processing unit. However, the function of the scan plan resetting unit may be provided to a different part from the image processing unit 46.

  In the second embodiment, the gantry side control unit 37 and the interface unit 42 function as a data generation unit. However, the function of the data generation unit may be provided to a different part from the gantry side control unit 37 and the interface unit 42.

  The scan control unit 41A and the preprocessing unit 43A function as an error range specifying unit, but the function of the error range specifying unit may be given to a different part from the scan control unit 41A and the preprocessing unit 43A.

  In the third embodiment, when the scan control unit 41B determines that the error range is distributed in a discrete manner, the error range having a discrete distribution excluding the normal range is used as the division error range. However, the scan control unit 41B performs threshold determination on the position intervals of the adjacent division error ranges, and if the position intervals are extremely narrow and less than the predetermined width, the adjacent division error ranges are grouped into one. The handling scan range may be reset as the error area.

  Further, the scan control unit 41B and the preprocessing unit 43B function as an error range specifying unit, but the function of the error range specifying unit may be provided to other parts different from the scan control unit 41B and the preprocessing unit 43B.

  Similarly, the image processing unit 46B functions as an error range display processing unit, but the function of the scan plan resetting unit may be given to a different part from the image processing unit 46B.

  P ... subject, 1 ... X-ray CT apparatus, 2 ... bed apparatus, 21 ... top plate, 22 ... top plate drive apparatus, 3 ... rotating mount, 31 ... subject insertion path, 32 ... mount drive apparatus, 33 ... X Line generator tube 34 ... X-ray detector 35 ... High voltage generator 36 ... DAS 37 Reference frame side control unit 4Console 41, 41A, 41B Scan control unit 42 Interface unit 43 43A ... Pre-processing unit, 44 ... Reconstruction processing unit, 45 ... Storage unit, 46, 46B ... Image processing unit, 47 ... Input device, 48 ... Display device.

  The present invention relates to an X-ray CT apparatus, and more particularly to a helical scan type X-ray CT apparatus.

  In recent years, a couch device that controls the position of a top plate that sends a subject to an X-ray irradiation field and enables continuous X-ray irradiation over a specified scan range set in a scan plan, and obtained transmission A helical scan type X-ray CT apparatus that collects X-ray attenuation rates as collected data and constructs an arbitrary tomographic image based on a continuous attenuation rate distribution in a scan range has been proposed (see Patent Document 1).

  "Scanning plan" defines various scanning conditions such as slice thickness, tube voltage and current, and X-ray intensity control conditions (modulation conditions), in addition to the scan range of the subject established based on scanograms, etc. Thus, it is prepared as a control program for the X-ray CT apparatus.

  The helical scan method has a higher scanning speed than the non-helical scan method (multi-scan method or the like), and greatly contributes to the reduction of the contrast agent and the enhancement of the contrast effect. In addition, the helical scan method can form an image from any continuous scan position without any breaks, and makes it possible to grasp the continuity of a tomographic image or a complex three-dimensional structure.

JP 2009-160270 A

  Occasionally, a vast amount of image data generated by the X-ray CT apparatus includes defective image data, and the displayed tomographic image may become unclear. The problem of image failure is a problem of image reliability, which leads to a diagnosis based on image observation and a reduction in quality of three-dimensional stereoscopic image display.

  In the helical scan that takes advantage of the high speed and continuity of the scan, the scan is continued even if the image data is partially defective. Therefore, when an image defect is noticed, it is necessary to scan again. In particular, it is necessary to avoid overlooking image defects such as being used for diagnosis without noticing image defects.

  Conventionally, when recognizing an image defect and redoing a scan, it is based on an empirical decision to check the acquired tomographic images one by one, or extra data added to the collected data on which the image data is based (accompanying information) Error occurrence (for example, the intensity and energy of irradiated X-rays, the focus position and focus size of the X-ray generator tube are abnormal, the occurrence of transmission errors in collected data), and the error occurrence range (the position of the couch top) ) And the like are checked to identify the necessary scan range. This work avoids unnecessary X-ray exposure of the subject by re-scanning the entire scan range, but in addition to reducing the accuracy of the scan range due to human error, it takes a lot of time and effort. It is necessary, and it is also a factor that decreases the throughput.

  The present invention has been made in view of the above circumstances, and when an image defect occurs, the image defect is automatically detected and can be prevented from being overlooked, and scanning limited to a scan range that needs to be redone is easy. An object of the present invention is to provide an X-ray CT apparatus that can be executed quickly and quickly.

In order to achieve the above-described object, the subject is imaged from one or a plurality of X-ray irradiation directions in accordance with a scan plan, and collected data composed of View data acquired for each of the one or a plurality of X-ray irradiation directions is acquired. Collection with supplementary information that correlates the data collection unit to be acquired, the view data, the error detection data at the time of obtaining the view data, and the top board position or the top board moving speed at the time of obtaining the view data. identify a data generating unit that generates data, a View erroneous data before Symbol error detection data to identify the top position or the error range of the top plate moving speed when acquiring the View data, If between the error range and error range contains normal range not an error range, a portion except for the normal range and error range specifying An error range specifying section that, characterized by comprising a.

Alternatively, a data collection unit that images a subject from one or a plurality of X-ray irradiation directions in accordance with a scan plan, and acquires collection data composed of View data acquired for each of the one or a plurality of X-ray irradiation directions; Data generation for generating collection data with accompanying information in which the View data, the error detection data at the time of obtaining the View data, and the top position or the top movement speed at the time of obtaining the View data are associated with each other And an error range specifying unit that sets the error ranges adjacent to each other as a single error range when the position interval is less than a predetermined width. It is provided with.

  Alternatively, a data collection unit that images a subject from one or a plurality of X-ray irradiation directions in accordance with a scan plan, and acquires collection data composed of View data acquired for each of the one or a plurality of X-ray irradiation directions; Data generation for generating collection data with accompanying information in which the View data, the error detection data at the time of obtaining the View data, and the top position or the top movement speed at the time of obtaining the View data are associated with each other And an error range specifying unit that expands the error range and sets a range equal to or larger than the predetermined width when an error range narrower than the predetermined width exists.

  According to the present invention, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and a scan limited to a scan range that needs to be redone can be performed easily and quickly.

1 is a functional block diagram showing a first embodiment of an X-ray CT apparatus according to the present invention. The figure which shows the structure of the collection data extra data produced | generated in the gantry side control part of FIG. 1, FIG. 2 (A) is a figure which shows the whole structure, FIG. 2 (B) is a figure which shows extra data. Explanatory drawing of the display process of the error range performed with the X-ray CT apparatus of FIG. The functional block diagram which shows 2nd Embodiment of the X-ray CT apparatus which concerns on this invention. The functional block diagram which shows 3rd Embodiment of the X-ray CT apparatus which concerns on this invention. Explanatory drawing of the display process of the error range performed with the X-ray CT apparatus of FIG.

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

(First embodiment)
FIG. 1 is a functional block diagram showing a first embodiment of an X-ray CT apparatus according to the present invention.

  As shown in FIG. 1, the X-ray CT apparatus 1 of the present embodiment includes a bed apparatus 2, a rotary mount 3, and a console 4.

[Bed equipment]
The bed apparatus 2 is configured so that the subject P is sent to the rotary base 3 serving as an X-ray irradiation field, and continuous X-ray irradiation can be performed on a predetermined scan range set in the scan plan.

  The top plate 21 can be slid with the subject P placed thereon, and the top plate driving device 22 slides the top plate 21 steplessly.

[Rotating base]
The rotating gantry 3 is configured to irradiate the subject P with X-rays and collect a continuous attenuation rate distribution of transmitted X-rays for a predetermined scan range set in the scan plan.

  The subject insertion passage 31 is capable of inserting the subject P placed on the top 21 and serves as an X-ray irradiation field for the subject P. A gantry driving device 32, an X-ray generator tube 33, an X-ray detector 34, a high voltage generator (X-ray generator) 35, a DAS (Data Acquisition System) 36, and the gantry side so as to surround the subject insertion passage 31 A control unit 37 is provided.

  The gantry driving device 32 is configured to be rotatable while holding the X-ray generation tube 33 and the X-ray detector 34 facing each other, and the X-ray generation tube 33 and the X-ray detector 34 having the subject insertion path 31 as a rotational center. Enables 360 ° turn.

  The X-ray generator tube 33 is supplied with a required tube voltage and tube current from the high voltage generator 35, and generates an X-ray fan beam from an arbitrary rotation position of 360 ° with an intensity and energy corresponding to the tube voltage and tube current. The target P is irradiated with X-rays.

  The X-ray detector 34 is configured as an X-ray detection element array in which a plurality of X-ray detection elements are two-dimensionally arranged in the body axis direction (axial direction) of the subject P and the body axis orthogonal direction (channel direction). . The X-ray detector 34 transmits transmitted X-rays that pass through the subject P that is radiated from the X-ray generation tube 33 that rotates around the subject insertion passage 31 and moves in the subject insertion passage 31, that is, the subject. The transmitted X-rays that have passed through the P helical trajectory are detected by each X-ray detection element, and an electrical signal corresponding to the attenuation rate (absorption rate) of the transmitted X-rays is output.

  The DAS 36 collects electrical signals output from the X-ray detection elements of the X-ray detector 34, performs integration (sample hold) for a predetermined time, AD converts the integration value, and converts the integration value into the body included in the subject P. Collected data in digital format reflecting the attenuation rate of X-rays by the tissue is generated.

  The gantry-side control unit 37 controls the tube voltage and tube current that determine the energy and intensity of the X-rays output from the high voltage generator 35 and radiated from the X-ray generator tube 33. The gantry-side control unit 37 uses the tube voltage and tube current output from the high voltage generator 35 (the tube voltage and tube current applied to the X-ray generation tube 33) as the X-ray characteristic tube voltage and tube current output values. Receive as.

  Further, the gantry-side control unit 37 outputs an X-ray timing signal that triggers the output and stop of tube voltage and tube current by the high voltage generator 35 (X-ray emission of the X-ray generator tube 33 and its stop), Also, a sample hold signal for controlling the sample hold time by the DAS 36 is generated.

  Further, the gantry-side control unit 37 receives the collected data output from the DAS 36 through the generation of the X-ray timing signal and the sample hold signal. The gantry-side control unit 37 adds the extra data (accompanying information) to the received collected data to generate collected data / extra data, and transmits the collected data / extra data to the console 4.

  FIG. 2 is a diagram showing the structure of collected data / extra data generated by the gantry-side control unit 37, FIG. 2 (A) is a diagram showing the overall structure, and FIG. 2 (B) is a diagram showing extra data. .

  Collected data / extra data (FIG. 2A) is one scan (hereinafter referred to as “X-ray irradiation position (position of the top plate 21)” and X-ray irradiation direction (position of the X-ray generation tube 33) of the subject P. , View), and the number of Views is generated.

  As shown in FIG. 2B, the extra data included in each collected data / extra data includes collected data such as “X-ray status”, “data transmission status”, “bed status”, and “table status”. It has information indicating the generation conditions.

  The X-ray status, which is one of the extra data, affects the image quality of the scanned image, such as the output values of the tube voltage and tube current received from the high voltage generator 35, the focus position and the focus size of the X-ray generator tube 33. Various conditions (X-ray characteristics) are recorded.

  In addition, an error flag indicating a transmission error of collected data / extra data is recorded in the data transfer status, and a position of the top board 21 and a moving speed thereof are recorded in the bed status. In addition, in the gantry status, a rotating part of the gantry driving device 32 that rotates the X-ray generation tube 33, a rotation speed and a rotation position of the X-ray generation tube 33, and the like are recorded.

  In addition, when sending the collected data / extra data to the console 4, the gantry-side control unit 37 adds a CRC (Cyclic Redundancy Check) code for checking whether there is a data transmission error for the collected data / extra data of each view. To do.

  The gantry-side control unit 37 collectively collects the collected data / extra data of a plurality of views according to the data transmission protocol, and transmits the collected data / extra data to the console 4 in packet units.

[console]
The console 4 controls the couch device 2 and the rotating gantry 3 and constructs a tomographic image of the subject P based on the continuous attenuation rate distribution of the scan range generated by the cooperation of the couch device 2 and the rotating gantry 3. And configured to display.

  In addition to the scan range of the subject P that is formulated based on a scanogram, the scan control unit 41 determines the slice thickness, the number of effective columns of the X-ray detection element array for each view, the tube voltage / tube current, and the X for each view. A scan plan (scan condition) such as a line intensity control condition (modulation condition) is held as a control program for the X-ray CT apparatus 1.

  The scan control unit 41 controls the top plate driving device 22, the gantry driving device 32, and the gantry side control unit 37 according to the scan plan, controls the position of the top plate 21, controls the rotation of the X-ray generation tube 33, and the gantry side control unit. The overall control of the helical scan is performed by setting the generation timing of 37 X-ray timing signals and sample hold signals.

  During execution of the helical scan controlled by the scan control unit 41, the interface unit 42 receives the collected data / extra data of each view generated on the rotating gantry 3 side and transmits it to the preprocessing unit 43.

  This interface unit 42 determines whether or not there is a transmission error for the collected data / extra data of each view based on the CRC code added by the gantry-side control unit 37 before transmitting the collected data / extra data to the pre-processing unit 43. I do.

  When it is determined that a transmission error has occurred in any of the collected data / extra data, the interface unit 42 records an error flag in the data transmission status of the collected data / extra data related to the transmission error.

  The preprocessing unit 43 performs calibration and sensitivity correction on the collected data included in the View collected data / extra data received from the interface unit 42 as preprocessing of the reconstruction processing executed by the reconstruction processing unit 44. Then, processing such as logarithmic conversion (Radon conversion) of the X-ray attenuation rate is performed to generate so-called projection data (raw data).

  The reconstruction processing unit 44 performs a reconstruction process based on the Fourier transform method or the filtered back projection method on the projection data generated by the preprocessing unit 43 to calculate an X-ray attenuation rate distribution (CT value distribution), Image data to be a tomographic image of the subject P is generated based on the X-ray attenuation rate distribution. The image data is stored in the storage unit 45.

  The image processing unit 46 generates various scan images such as a tomographic image and a three-dimensional stereoscopic image based on the image data stored in the storage unit 45. The input device 47 includes an operation device such as a keyboard and a mouse for instructing the image processing unit 46 on display conditions desired by the user, such as image contrast and a region of interest (Region of Interest). The scan image generated by the processing unit 46 is displayed according to the specified display condition.

  The scan control unit 41, the preprocessing unit 43, and the image processing unit 46 of the X-ray CT apparatus 1 cooperate to execute a scan plan resetting process and an error range display process. Hereinafter, steps in each process will be described.

[Scan range reset processing]
The scan plan resetting process is executed when the collection data group of all the views, which is the basic data of the image data, includes abnormal collection data. In other words, a process for automatically setting a scan plan related to the scan re-execution. It is.

(Step 101)
The pre-processing unit 43 uses the X-rays actually irradiated on the subject P in each view based on the output values of the tube voltage and tube current recorded in the collected data and extra data of each view received from the interface unit 42. Determines whether the tube voltage and tube current are normal or abnormal.

  As a start process of this determination, the pre-processing unit 43 sets the set values (planned values) of the tube voltage and the tube current of each View that will follow the path of the scan control unit 41 → the gantry side control unit 37 → the high voltage generator 35. ) Is received directly from the scan control unit 41 each time the set value is generated.

(Step 102)
The pre-processing unit 43 sets the tube voltage and tube current setting values of the view received from the scan control unit 41, and the tube voltage and tube current recorded in the collected data / extra data of each view received from the interface unit 42. It is determined whether the output value matches or does not match.

(Step 103)
When determining that the set values of the tube voltage and tube current and the output values of the tube voltage and tube current do not match, the preprocessing unit 43 calculates a difference between the set value and the output value. If it is determined that the set value matches the output value, the process does not proceed to the following step.

(Step 104)
A threshold is determined for the difference between the tube voltage and tube current output value and the set value of the tube voltage and tube current, and a high voltage is generated for a view where the difference between the tube voltage and tube current output value and the set value exceeds the threshold value. It is determined that the output values of the tube voltage and tube current output by the apparatus 35, that is, the intensity and energy of the irradiated X-rays irradiated to the subject P are abnormal.

(Step 105)
When the preprocessing unit 43 determines that the output values of the tube voltage and the tube current are abnormal, the preprocessing unit 43 reads the data on the top position recorded in the collected data / extra data of the View corresponding to the determination result. Then, the preprocessing unit 43 sends the read data of the top board position to the scan control unit 41.

(Step 106)
The scan control unit 41 cumulatively collects and adds the top plate positions, and the position of the top plate 21 at the time when the output values of the tube voltage and the tube current are abnormal and immediately before the abnormality is resolved. The position of the top plate 21 is specified. Then, the scan control unit 41 sets the movement range of the top plate 21 determined by the two specified positions of the top plate 21 as an error range.

(Step 107)
The scan control unit 41 uses the stored current scan plan as it is for other conditions excluding the scan range, and for the scan range, substitutes the error range specified in step 106 as “Redo”. It is generated and memorized as “scan plan”.

  When the X-ray CT apparatus 1 executes another scan based on the “redo scan plan”, it is conditional on having received an operator scan start request.

[Error range display processing]
The error range display process is a process of displaying the error range on the screen of the display device 48 based on the result of the scan image resetting process.

(Step 201)
The scan control unit 41 sends the top position data received from the preprocessing unit 43 to the image processing unit 46.

(Step 202)
The image processing unit 46 specifies the error range based on processing similar to Step 106 and Step 107 executed by the scan control unit 41 using the data on the top position received from the preprocessing unit 43.

(Step 203)
The image processing unit 46 displays the error range specified in step 202 on the display device 48. At this time, as shown in FIG. 3, the image processing unit 46 displays the error range so as to overlap the scanogram image acquired in advance and stored in the storage unit 45 in order to set the scan range.

  Next, the effect will be described.

In the X-ray CT apparatus 1,
(1) The X-ray tube voltage and tube current output values (X-ray characteristics) irradiated to the subject P and the couch position of the couch device 2 are used as extra data, and this extra data corresponds to the collected data of each view. A gantry-side control unit 37 that generates collected data and extra data is provided. Also, whether the tube voltage and tube current output values included in the collected data and extra data match the default tube voltage and tube current set in the scan plan, i.e., whether the tube voltage and tube current are set. A scan control unit 41 and a pre-processing unit 43 that determine and read the top plate position from the collected data / extra data including the output values of the tube voltage and the tube current that do not match and set the total of the read top plate positions as an error range are provided. .

  For this reason, when the high voltage generator 35 is temporarily discharged during the execution of the helical scan and the required tube voltage and tube current set in the scan plan are not applied to the X-ray generator tube 33, this problem is caused. Is automatically detected. That is, an abnormality in collected data accompanying discharge or an image defect based on this is automatically detected. Therefore, since no human error is involved in detecting an image defect, the reliability of the image defect detection is extremely good.

  In addition, the scan control unit 41 is configured to replace the default scan range set in the scan plan with the error range specified by the scan control unit 41 and the pre-processing unit 43 and to make a rescan plan. Therefore, in addition to automatically specifying an error range in which an image defect has occurred and it is necessary to perform scanning again, a scan plan limited to the specified error range is automatically created. Then, when there is a scan start request from the operator (the operator only makes a scan start request), a “redo scan plan” limited to the error range is executed.

  In short, according to the X-ray CT apparatus 1, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and the scan limited to the scan range that needs to be redone can be easily performed. Can be executed quickly.

  (2) An image processing unit 46 that displays the specified error range superimposed on the scanogram image of the subject P including the predetermined scan range set in the scan plan is provided. For this reason, in the case where the scan re-execution is executed on the condition that the operator requested to start the scan, the operator can easily determine whether the scan re-execution is necessary. For example, even if the tomographic image displayed on the display device 48 is unclear, when such an image defect is out of the region of interest, there is no need to repeat the scan. According to the X-ray CT apparatus 1, such a determination becomes easy.

(Second Embodiment)
FIG. 4 is a functional block diagram showing a second embodiment of the X-ray CT apparatus according to the present invention.

  The present embodiment is an example in which the configurations of the preprocessing unit 43 and the scan control unit 41 in the X-ray CT apparatus 1 of the first embodiment are changed. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol, description is abbreviate | omitted, and the structure which changed the structure of 1st Embodiment, or was newly added attaches | subjects "A" to the code | symbol end, and demonstrates it .

  As shown in FIG. 4, the X-ray CT apparatus 1A of the present embodiment includes a scan control unit 41A and a preprocessing unit 43A.

  The scan control unit 41A and the preprocessing unit 43A cooperate to execute a scan plan resetting process based on the presence / absence determination of an error flag. Hereinafter, each step in the scan plan resetting process will be described.

(Step 301)
When the preprocessing unit 43A receives the collected data / extra data from the interface unit 42, the preprocessing unit 43A indicates the presence / absence of an error flag recorded in the data transmission status of the collected data / extra data of each view, that is, a data transmission error. Determine the presence or absence of information.

(Step 302)
When determining that the error flag is recorded, the pre-processing unit 43A reads the data on the “top position” recorded in the bed status of the collected data / extra data of the View in which the error flag is recorded. Then, the preprocessing unit 43A sends the read data of the top board position to the scan control unit 41A.

(Step 303)
The scan control unit 41A collects the data of the top board position received from the preprocessing unit 43A, and the position of the top board 21 at the time when the data transmission error occurs and the top board 21 immediately before the data transmission error is eliminated. Identify the location. Then, the scan control unit 41A sets the error range as the movement range of the top plate 21 determined by the two specified positions of the top plate 21.

(Step 304)
As in the first embodiment, the scan control unit 41A uses the other conditions excluding the scan range in the stored current scan plan as they are, and the error specified in step 303 for the scan range. A “redo scan plan” is generated and stored using the range. The other processes in the scan range resetting process and the error range display process are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, the effect will be described.

In the X-ray CT apparatus 1A,
(3) It is determined whether or not a transmission error has occurred in the collected data, and an error flag indicating that a transmission error has occurred and the table top position of the bed apparatus 2 are used as extra data, and this extra data is associated with the collected data of each view. In addition, a gantry-side control unit 37 and an interface unit 42 that generate collected data and extra data are provided. Also, it is determined whether or not an error flag is included in the collected data / extra data, scan position is read from the collected data / extra data including the error flag, and the total of the top position is the error range. 41A and the pre-processing part 43A are provided.

  For this reason, when a transmission error of collected data occurs, this transmission error is automatically detected. That is, an image defect based on a transmission error is automatically detected. Accordingly, since no human error is involved in detecting an image defect, the reliability of the image defect detection is extremely high.

  In addition, the scan control unit 41A is configured to replace the default scan range set in the scan plan with the error range specified by the scan control unit 41A and the pre-processing unit 43A, thereby forming a rescan plan. Therefore, in addition to automatically specifying an error range in which an image defect has occurred and it is necessary to perform scanning again, a scan plan limited to the specified error range is automatically created. Then, when there is a scan start request from the operator (the operator only makes a scan start request), a second scan limited to the error range is executed.

  In short, according to the X-ray CT apparatus 1A, when an image defect occurs, the image defect is automatically detected to prevent the detection from being overlooked, and the scan limited to the scan range that needs to be redone can be easily performed. Can be executed quickly.

(Third embodiment)
FIG. 5 is a functional block diagram showing a third embodiment of the X-ray CT apparatus according to the present invention.

  The present embodiment is an example in which the configurations of the scan control unit 41 and the image processing unit 46 in the X-ray CT apparatus 1 of the first embodiment are changed. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol, abbreviate | omits description, The structure which changed the structure of 1st Embodiment or added newly is attached | subjected with a code | symbol "B", and is demonstrated. .

  As shown in FIG. 5, the X-ray CT apparatus 1B of the present embodiment includes a scan control unit 41B and an image processing unit 46B.

  The scan control unit 41B and the image processing unit 46B cooperate to execute scan plan resetting processing and division error range display processing performed by dividing the error range. Hereinafter, each step in the scan plan resetting process will be described.

(Step 401)
The scan control unit 41B determines whether the error range identified in step 107 is continuous along the body axis direction of the subject P following the processing of step 101 to step 107 in the scan range resetting process of the first embodiment. Or it determines whether it is not continuous (it distributes discretely). That is, it is determined whether or not a normal range that is not an error range is included between the error range specified in step 107 and the error range.

  When the scan control unit 41B determines that the error range is distributed discretely, each error range in the discrete distribution form excluding the normal range is set as a divided error range.

(Step 402)
Similarly to the first embodiment, the scan control unit 41B uses other conditions excluding the scan range in the stored current scan plan as they are, and the scan range specified in step 401 is divided. A substitute for the error range is generated and stored as a redo scan plan.

[Division error range display processing]
The error range display process is a process of displaying the division error range on the screen of the display device 48 based on the result of the scan image resetting process.

(Step 501)
The scan control unit 41B sends the top position data received from the preprocessing unit 43 to the image processing unit 46B.

(Step 502)
The image processing unit 46B uses the top position data received from the scan control unit 41B, and based on the processing similar to the processing in step 106 and step 107 in the scan range resetting processing of the first embodiment, the error range. Is identified.

(Step 503)
The image processing unit 46B determines that the error range specified in step 502 is continuous along the body axis direction of the subject P based on the same processing as the processing in step 401 executed by the scan control unit 41B. Determine if it is not continuous.

  When the image processing unit 46B determines that the error ranges are distributed in a discrete manner, each error range in the discrete distribution form excluding the normal range is set as a divided error range.

(Step 504)
The image processing unit 46B displays the specified division error range on the display device 48. At this time, as shown in FIG. 6, the image processing unit 46 </ b> B displays the division error range so as to overlap the scanogram image acquired in advance and stored in the storage unit 45 in order to set the scan range.

  Next, the effect will be described.

In the X-ray CT apparatus 1B, in addition to the effects (1) and (2) of the first embodiment, the following effects can be obtained. ◎
(4) It is determined whether a normal range that is not an error range is included between the error range and the error range. If it is determined that such a normal range is included, the portion excluding the normal range is A scan control unit 41B and a preprocessing unit 43B are provided as division error ranges.

  For this reason, even when the scan re-execution is executed without the operator's scan start request as a condition, it is possible to avoid the scan re-execution including the normal range. That is, in the first embodiment, even if the region of interest is located between the error ranges and a good image is obtained for the region of interest, the first error range starts from the start position. There is a possibility that another scan may be executed in the range up to the end position of the next error range. According to the X-ray CT apparatus 1B of the present embodiment, even if the error range is distributed at intervals, it is possible to rescan the pinpoint only for the scan range related to the image defect, and the subject P is wasted. Exposure can be avoided.

  (5) An image processing unit 46B that displays the specified division error range superimposed on the scanogram image of the subject P including the predetermined scan range set in the scan plan is provided. For this reason, in the case where the scan re-execution is executed on the condition that the operator requested to start the scan, the operator can easily determine whether the scan re-execution is necessary, as in the effect (2) of the first embodiment.

  The X-ray CT apparatus according to the present invention has been described based on one of the first to third embodiments, but the specific configuration is not limited to these embodiments, and Design changes and additions are permitted without departing from the scope of the invention described in the scope.

  In the first embodiment, an example in which X-ray characteristics of tube voltage and tube current output values output from the high voltage generator 35 are used as an index for specifying an error range (a scan range in which an image is defective). However, since the X-ray characteristics used for specifying the error range are selected as X-ray conditions that affect the image quality of the scanned image, instead of the output values of the tube voltage and tube current, The X-ray focal position or the X-ray focal spot size may be used.

  Further, as the X-ray characteristics, both the tube voltage output value and the tube current output value may be used, and either the tube voltage output value or the tube current output value may be used.

  Further, when the specified error range is narrower than the predetermined width in the process of step 107 in the scan range resetting process (for example, when an X-ray characteristic abnormality occurs in one view), the error range is You may make it expand an error range so that it may become more than predetermined width. If the displayed tomographic image is too narrow, it cannot be used for diagnosis, but the significance of re-scanning can be ensured by expanding the error range. For the same purpose, the threshold value may be determined for the width of the error range, and if the error range is extremely narrow and does not satisfy the predetermined width, the scan may not be performed again.

  Further, the X-ray CT apparatus 1 is an example on the condition that a scan start request from the operator is received when performing another scan based on the “redo scan plan”. However, the scan start request from the operator is not a condition, and a redo scan may be automatically executed when a preset image defect occurs in a preset scan range (for example, a region of interest). Good.

  Further, in the process of step 202 in the error range display process, the image processing unit 46 specifies an error range based on the same process as the step 106 and step 107 executed by the scan control unit 41. . However, the image processing unit 46 may use the error range specified in the process of step 107 without specifying the error range.

  The gantry-side control unit 37 adds an CRC code for checking whether there is a data transmission error to the collected data / extra data of each view when transmitting the collected data / extra data to the console 4. Since the CRC code is added to check whether there is a transmission error for the collected data, any other code that allows such a check can be used instead of the CRC code.

  Further, although the gantry side control unit 37 functions as a data generation unit, the function of the data generation unit may be given to a different part from the gantry side control unit 37.

  Further, although the scan control unit 41 and the preprocessing unit 43 function as a data range specifying unit, the function of the data range specifying unit may be given to a different part from the scan control unit 41 and the preprocessing unit 43.

  The scan control unit 41 functions as a scan plan resetting unit, but the function of the scan plan resetting unit may be given to a different part from the scan control unit 41.

  The image processing unit 46 functions as an error range display processing unit. However, the function of the scan plan resetting unit may be provided to a different part from the image processing unit 46.

  In the second embodiment, the gantry side control unit 37 and the interface unit 42 function as a data generation unit. However, the function of the data generation unit may be provided to a different part from the gantry side control unit 37 and the interface unit 42.

  The scan control unit 41A and the preprocessing unit 43A function as an error range specifying unit, but the function of the error range specifying unit may be given to a different part from the scan control unit 41A and the preprocessing unit 43A.

  In the third embodiment, when the scan control unit 41B determines that the error range is distributed in a discrete manner, the error range having a discrete distribution excluding the normal range is used as the division error range. However, the scan control unit 41B performs threshold determination on the position intervals of the adjacent division error ranges, and if the position intervals are extremely narrow and less than the predetermined width, the adjacent division error ranges are grouped into one. The handling scan range may be reset as the error area.

  Further, the scan control unit 41B and the preprocessing unit 43B function as an error range specifying unit, but the function of the error range specifying unit may be provided to other parts different from the scan control unit 41B and the preprocessing unit 43B.

  Similarly, the image processing unit 46B functions as an error range display processing unit, but the function of the scan plan resetting unit may be given to a different part from the image processing unit 46B.

  P ... subject, 1 ... X-ray CT apparatus, 2 ... bed apparatus, 21 ... top plate, 22 ... top plate drive apparatus, 3 ... rotating mount, 31 ... subject insertion path, 32 ... mount drive apparatus, 33 ... X Line generator tube 34 ... X-ray detector 35 ... High voltage generator 36 ... DAS 37 Reference frame side control unit 4Console 41, 41A, 41B Scan control unit 42 Interface unit 43 43A ... Pre-processing unit, 44 ... Reconstruction processing unit, 45 ... Storage unit, 46, 46B ... Image processing unit, 47 ... Input device, 48 ... Display device.

Claims (9)

Transmitted X-ray obtained by providing a bed device that controls the position of the top plate that sends the subject to the X-ray irradiation field and enables continuous X-ray irradiation within the predetermined scan range set in the scan plan In the helical scan type X-ray CT apparatus that collects the attenuation rate of the data as collected data and constructs an arbitrary tomographic image based on the continuous attenuation rate distribution in the scan range,
A data generation unit that associates the X-ray characteristics of the X-rays irradiated on the subject and the table top position of the bed apparatus with extra data and associates the extra data with the collected data of each view;
It is determined whether or not the X-ray characteristic included in the extra data matches a predetermined X-ray characteristic set in the scan plan, and the top position is determined from the extra data including the X-ray characteristic that does not match the predetermined X-ray characteristic. An error range specifying unit for specifying an error range based on the read top plate position,
An X-ray CT apparatus comprising: The X-ray CT apparatus according to claim 1,
An X-ray CT apparatus using at least one of a tube voltage applied to an X-ray generation tube, a tube current, a focus position of the X-ray generation tube, and a focus size as the X-ray characteristics. Transmitted X-ray obtained by providing a bed device that controls the position of the top plate that sends the subject to the X-ray irradiation field and enables continuous X-ray irradiation within the predetermined scan range set in the scan plan In the helical scan type X-ray CT apparatus that collects the attenuation rate of the data as collected data and constructs an arbitrary tomographic image based on the continuous attenuation rate distribution in the scan range,
A data generation unit that determines whether or not a transmission error has occurred in the collected data, sets an error flag indicating the occurrence of a transmission error and the top position of the bed apparatus as extra data, and associates the extra data with the collected data of each view When,
It is determined whether or not an error flag is included in the extra data, the top plate position is read from the extra data including the error flag, and an error range specifying unit that specifies an error range based on the top plate position;
An X-ray CT apparatus comprising: The X-ray CT apparatus according to any one of claims 1 to 3,
An X-ray CT apparatus comprising: a scan plan resetting unit configured to replace a predetermined scan range set in the scan plan with an error range specified by an error range specifying unit to make a rescan plan. The X-ray CT apparatus according to any one of claims 1 to 4,
The error range specifying unit determines whether or not a normal range that is not an error range is included between the error range and the error range, and when determining that such a normal range is included, the normal range is determined. An X-ray CT apparatus characterized in that an excluded range is an error range. The X-ray CT apparatus according to any one of claims 1 to 5,
The X-ray CT apparatus, wherein when the error range is narrower than a predetermined width, the error range specifying unit expands the error range so that the error range becomes a predetermined width or more. The X-ray CT apparatus according to any one of claims 1 to 6,
An X-ray CT apparatus comprising: an error range display processing unit that displays an error range specified by the error range specifying unit on a screen of a display device. The X-ray CT apparatus according to claim 7,
The X-ray CT apparatus, wherein the error range display processing unit displays an error range so as to be superimposed on a scanogram image of a subject including a predetermined scan range set in a scan plan. In the X-ray CT apparatus according to any one of claims 1 to 8,
An X-ray CT apparatus that executes a helical scan based on a rescan plan on condition that a scan start request is made by an operator.