JP2007111255A - X-ray ct equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide X-ray CT equipment where main photographing is carried out at a proper timing in photographing of a tomogram using a contrast medium. <P>SOLUTION: A monitoring area of the examinee to be photographed for monitoring, a threshold A for starting auto voice and a threshold B for starting photographing are set (S102). A control part 3 starts photographing for monitoring, and a concentration value calculation part 2b obtains a monitoring CT value (S105). When the monitoring CT value amounts to the threshold A for starting auto voice, the auto voice is started (S108). When the monitoring CT value amounts to the threshold B for starting photographing, the main photographing is started (S119). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus, and more particularly to an X-ray CT apparatus capable of performing main imaging at an optimal timing in tomographic imaging using a contrast agent.

  2. Description of the Related Art Conventionally, there is a technique for capturing a contrasted blood vessel image at an optimal contrast timing after contrast medium injection when a contrast medium is injected into a subject and a contrast blood vessel image is captured.

For example, in the X-ray CT apparatus described in Patent Document 1, as shown in FIG. 14, after taking a tomographic image of an object at a monitoring position in a subject injected with a contrast agent (S401), CT on the tomographic image The location where the value is monitored, the threshold value for the CT value to be monitored, and the monitoring time (T) are set (S402). Next, monitoring imaging (monitoring scan) for CT value monitoring is performed (S403). When monitoring imaging is started, the average CT value of the monitoring location is calculated for each imaging (S405), and the elapsed time (t) of monitoring imaging is started (S406). When the set monitoring time has elapsed from the start of monitoring imaging (S407), or when the monitoring CT value exceeds a threshold value (S408), monitoring imaging is terminated and automatic utterance (auto voice) is performed (S409). Next, photographing (main scan) for obtaining an image to be finally obtained is performed (S410).
Japanese Patent Laid-Open No. 11-28202

  In Patent Literature 1, after satisfying the condition for shifting to the main shooting in the monitoring shooting, the main shooting is performed by uttering an auto voice for prompting a preparatory action necessary for the main shooting. However, in the case of auto voice utterance, a certain time such as several seconds is usually required. Therefore, there is a delay in shifting to the main shooting, and there is a problem that the main shooting cannot be performed at the timing when the actual shooting is desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray CT apparatus capable of performing main imaging at an appropriate timing in tomographic imaging using a contrast agent. To do.

  In order to achieve the above object, an X-ray CT apparatus according to the present invention is arranged to face an X-ray source that irradiates an X-ray and an X-ray source across a subject and detect the X-ray. An X-ray detector that outputs projection data, a rotating means that can be rotated by mounting the X-ray source and the X-ray detector, the X-ray source, the X-ray detector, and the rotating means, Imaging control means for controlling and executing imaging; image processing means for reconstructing a tomographic image of the subject based on the projection data; display means for displaying the reconstructed tomographic image; A region of interest setting means for setting a region of interest on a tomographic image, a concentration value calculating means for calculating a concentration value of the set region of interest, and a contrast blood vessel image of the subject injected with a contrast agent Threshold for monitoring to determine when to start instructions for preparatory actions necessary for actual shooting And a threshold setting means for setting a monitoring threshold value that is lower than the density value at the time of the main photographing, and an instruction means for instructing the preparatory action, wherein the photographing control means includes the main photographing. Prior to the monitoring, radiographic imaging is performed for imaging the same part of the subject for a predetermined time and monitoring the density value of the part, and the density value calculating means is configured to display the interest set on the tomographic image obtained by the monitoring imaging. The density value of the area is calculated, and when the density value is equal to or greater than the monitoring threshold, the instruction means starts an instruction for the preparatory action.

  The threshold setting unit further sets a shooting threshold for determining the start time of the main shooting, and the shooting control is performed when the density value calculated by the density value calculating unit is greater than or equal to the shooting threshold. The means may control the start of the main photographing.

  Further, a monitoring number measuring unit that measures the number of times that the photographing control is performed by the photographing control unit after the instruction of the preparatory action is performed, or an elapsed time from when the photographing control unit starts the monitoring photographing, or At least one of time measuring means for measuring an elapsed time since the instruction by the instruction means is performed, and when the number of times of monitoring photographing measured by the monitoring number measuring means is a predetermined number or more, or the monitoring photographing When the elapsed time since the start is equal to or longer than a predetermined time or when the elapsed time since the instruction by the instruction means is equal to or longer than the predetermined time, the imaging control means may control the start of the actual imaging. .

  According to the present invention, there is provided a threshold value for determining the start time of a preparatory action instruction necessary for actual shooting, which is a value lower than the density value at the time of actual shooting. When the density value of the region of interest exceeds a threshold value during monitoring imaging, a preparatory action instruction is started. Therefore, it is possible to perform the main shooting at an appropriate shooting timing.

  Hereinafter, preferred embodiments of an X-ray CT apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the following, the CT value refers to the concentration value of the contrast agent in the tomographic image.

<First embodiment>
A hardware configuration of the X-ray CT apparatus 1 according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a hardware configuration of the X-ray CT apparatus 1. FIG. 2 is a diagram showing the positional relationship between the X-ray tube 41 and the detector 43. In the following, an auto voice will be described as an example of an instruction means for instructing a subject to perform a preparatory action for main imaging.

  The X-ray CT apparatus 1 includes a central processing unit 2, a control unit 3, a scanner 4, an image processing unit 5 and a console 6, and a bed (not shown).

  When the operator performs monitoring imaging using a contrast agent, a scan plan is set and set as to which position of the subject 7 is monitored and how much tomographic image is reconstructed.

  The central processing unit 2 is composed of a CPU and controls the operation of the X-ray CT apparatus 1. Further, the central processing unit 2 processes information related to the scan plan, and the X-ray control unit 31, the collimator control unit 32, and the scanner control unit 33 control the scanner 4.

  The control unit 3 includes an X-ray control unit 31, a collimator control unit 32, and a scanner control unit 33. The X-ray control unit 31 controls the tube current applied to the X-ray tube 41 and adjusts the X-ray dose to be irradiated. The collimator control unit 32 controls the collimator 42 to adjust the X-ray irradiation angle. The scanner control unit 33 controls the scanner 4 and controls the X-ray source 41, a bed (not shown), the rotation operation of the detector 43, and the like.

  The scanner 4 is mounted with an X-ray tube 41 and a detector 43 and rotates. The X-ray tube 41 and the detector 43 are fixed at positions facing each other across the imaging region of the subject 7. X-rays are emitted from the X-ray tube 41 during one rotation, and transmitted X-ray data after passing through the subject 7 is detected by the detector 43. The collimator 42 adjusts the X-ray irradiation angle. The detector 43 is composed of a plurality of detection elements, and assigns a channel number of each detection element to transmitted X-ray data obtained from the elements. The speaker 44 is an audio playback device.

  Further, assuming that the number of times of sampling during one rotation of the scanner 4 is the number of views, the transmission X-ray data for one rotation obtained from the detector 43 is converted into two-dimensional projection data by the projection data conversion unit 51 and projected. Output as data. FIG. 3 is a diagram showing an example of two-dimensional projection data. The data horizontal direction is the channel number of the detector 43, and the vertical direction is the number of views.

  The reconstruction processing unit 52 performs filtering (convolution method) and back projection (back projection) processing on the projection data to reconstruct a tomographic image of the subject 7.

  The operation unit 61 of the console 6 is a keyboard, a mouse, or the like, and accepts an operator's operation. The image display unit 62 is a monitor, and displays various information such as numerical information in addition to the reconstructed tomographic image.

  A program executed by the central processing unit 2 will be described with reference to FIG. FIG. 4 is a block diagram showing a configuration of a program executed by the central processing unit 2.

  The program includes a region-of-interest setting unit 2a, a density value calculation unit 2b, a threshold value setting unit 2c, an instruction unit 2d, a monitoring frequency measuring unit 2e, and a time measuring unit 2f.

  The region-of-interest setting unit 2a sets a region of interest (hereinafter referred to as a monitoring region) on which a concentration value is to be monitored on a tomographic image when a contrast medium is administered to the subject.

  The density value calculation unit 2b calculates the density value of the set monitoring area. Hereinafter, the density value of the monitoring area is referred to as a monitoring CT value.

  The threshold value setting unit 2c is a monitoring threshold value for determining the start time of a preparation action instruction necessary for main imaging for obtaining a contrast-enhanced blood vessel image of a subject injected with a contrast agent. A monitoring threshold value that is lower than the density value is set. Hereinafter, the monitoring threshold is referred to as an auto voice monitoring threshold A.

  Further, the threshold setting unit 2c further sets a shooting threshold for determining the start time of the main shooting. Hereinafter, the shooting threshold is referred to as a shooting start threshold B.

  The instruction unit 2d instructs a preparatory action. The start of the instruction is when the monitoring CT value is greater than or equal to the auto voice monitoring threshold A. In the present embodiment, an auto voice is uttered through the speaker 44, and an action to stop breathing is instructed as a preparation action.

  The monitoring frequency measuring unit 2e measures the number of times that the monitoring shooting has been performed after the instruction for the preparatory action is performed.

  The timer unit 2f measures an elapsed time after the control unit 3 starts monitoring imaging or an elapsed time after the instruction by the instruction unit 2d is performed.

  The program is stored in a storage device (not shown) provided in the central processing unit 2. The central processing unit 2 reads these programs from the storage device and executes them.

  Next, monitoring imaging of the X-ray CT apparatus 1 will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of monitoring shooting processing according to this embodiment.

(Step S101)
In S101, the operator performs scan shooting. The projection data conversion unit 51 and the reconstruction processing unit 52 reconstruct a tomographic image (S101).

(Step S102)
In S <b> 102, the image display unit 62 displays a screen (setting screen) for setting conditions (monitoring conditions) related to monitoring imaging. FIG. 6 is a diagram showing a screen display example for setting monitoring conditions. On the setting screen 70, a tomographic image 71 reconstructed in S101 and a setting area 73 for setting monitoring conditions are displayed.

The setting area 73 includes an auto voice start threshold A for executing the main shooting, a shooting start threshold B for determining the start of the main shooting, and a predetermined elapsed time monitoring time after the start of the monitoring shooting ( Monitoring time T ₁ ), a predetermined elapsed time after the instruction by the instruction unit ₂ d (automatic voice monitoring time T ₂ ), and a predetermined number of times of monitoring photographing after the instruction by the instruction unit ₂ d ( An input field for the number of post-autovoice monitoring times M) is provided. The threshold setting unit 2c acquires the threshold input from the setting area 73, and sets the auto voice start threshold A and the shooting start threshold B.

  The region-of-interest setting unit 2 a receives input from the operator via the operation unit 61 and performs processing for setting the monitoring region 72 on the tomographic image 71. The set monitoring area 72 is displayed on the tomographic image 71. (S102). Note that the auto voice start threshold A and the imaging start threshold B are adjusted and set according to the subject.

  After the above setting process is completed, a contrast agent is injected into the subject 7. Note that the injection of the contrast agent into the subject 7 may be performed automatically or manually.

(Step S103)
In S103, the monitoring elapsed time t ₁ indicating the elapsed time since the start of monitoring, the post-auto voice monitoring elapsed time t ₂ indicating the elapsed time after the auto voice, and the auto indicating the number of times the monitoring shooting is performed after the auto voice. The post-voice monitoring elapsed number m is initialized (S103).

(Step S104)
In S104, the control unit 3 starts monitoring imaging (monitoring scan). The image processing unit 5 reconstructs a tomographic image from the projection data obtained by monitoring imaging (S104).

(Step S105)
In S105, the density value calculation unit 2b calculates the monitoring CT value of the monitoring area 72 set in S102 (S105). The concentration value calculation unit 2b may calculate the average CT value of the monitoring region 72 or may calculate the highest CT value in the monitoring region 72 (corresponding to the concentration value of the region where the contrast agent concentration is high). Good.

(Step S106)
In S106, timer unit 2f starts counting the monitoring time elapsed t _1.

The image display unit 62 displays a screen (monitoring screen) indicating the result of monitoring shooting. FIG. 7 is a diagram illustrating a screen display example of the monitoring screen. On the monitoring screen 74, in addition to the tomographic image 71, the monitoring area 72, and the setting area 73 reconstructed in S101, a monitoring image 75 that is a tomographic image obtained by monitoring imaging and a monitoring CT value transition graph 76 are displayed. Is done. The horizontal axis of the monitoring CT value transition graph 76 indicates the monitoring elapsed time t ₁ , and the vertical axis indicates the monitoring CT value.

(Step S107)
In S107, the density value calculator 2b determines whether or not the monitored CT value is larger than the auto voice start threshold A (S107). If the monitored CT value is larger than the auto voice start threshold A, the process proceeds to S108. If the monitored CT value is smaller than the auto voice start threshold A, the process returns to S105.

(Step S108)
In S108, the instruction unit 2d utters an auto voice (S108). The instruction unit 2d instructs the subject to hold his / her breath as a preparatory action. For example, say "Please hold your breath." Note that the utterance content may instruct body movement suppression.

(Step S109)
In S109, the density value calculation unit 2b acquires a monitoring CT value (S109).

(Step S110)
In S110, it is determined whether or not the monitoring CT value is larger than the imaging start threshold B (S110). When the monitoring CT value is larger than the imaging start threshold B, the process proceeds to S119. If the monitoring CT value is smaller than the imaging start threshold B, the process returns to S109.

(Step S111)
In S111, timer unit 2f obtains the monitoring elapsed time _{t 1} (S111).

(Step S112)
In S112, the monitoring elapsed time _{t 1} whether larger monitoring time T ₁ is is determined (S112). If monitoring the elapsed time _{t 1} is greater than the monitoring time T _1, the process proceeds to S119. When monitoring the elapsed time _{t 1} the monitoring time T ₁ smaller than, returns to S111.

(Step S113)
In S113, timer unit 2f starts measuring after the auto voice monitoring elapsed time _{t 2} (S113).

(Step S114)
In S114, timer unit 2f obtains after auto voice monitoring elapsed time _{t 2} (S114).

(Step S115)
In S115, the automatic voice after monitoring the elapsed time _{t 2} is whether auto voice after monitoring time _{T 2} is greater than is determined (S115). If the auto-voice after monitoring the elapsed time _{t 2} is greater than the auto-voice after the monitoring time _{T 2,} the process proceeds to S119. Auto voice after monitoring the elapsed time _{t 2} if the auto voice after the monitoring time _{T 2} smaller than, returns to S114.

(Step S116)
In S116, the monitoring frequency measuring unit 2e starts measuring the post-autovoice monitoring elapsed number m (S116).

(Step S117)
In S117, the monitoring frequency measuring unit 2e obtains the post-autovoice monitoring elapsed frequency m (S117).

(Step S118)
In S118, it is determined whether or not the post-autovoice monitoring elapsed number m is larger than the post-autovoice monitoring number M (S118). If the post-autovoice monitoring elapsed number m is larger than the post-autovoice monitoring number M, the process proceeds to S119. When the post-auto-voice monitoring count m is smaller than the post-auto-voice monitoring count M, the process returns to S117.

(Step S119)
In S119, the control unit 3 ends the monitoring shooting through the scanner 4 and starts the main shooting (main scan) (S119).

According to the present embodiment, a monitoring region is set on the reconstructed tomographic image, and a tomographic image at the same position is taken for a certain period of time after the contrast medium is administered to the subject. The monitor CT value is observed, and when the monitor CT value reaches a preset auto voice start threshold A, auto voice is started. Also, if the monitoring CT value exceeds a shooting start threshold B, and monitoring elapsed time t ₁ exceeds the monitoring time T _1, when the monitoring elapsed time t ₁ has exceeded the monitoring time T _1, or auto voice after When the number of times of monitoring m exceeds the number of times of monitoring M after auto-voice, actual shooting is performed. For this reason, the main shooting can be started when the preparatory action is completed, and the main shooting can be performed at an appropriate timing.

<Second embodiment>
In the present embodiment, a plurality of preparatory actions at different times are instructed to the subject 7, and the threshold setting unit 2c sets an auto voice start threshold for each preparatory action. Hereinafter, monitoring imaging according to the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of monitoring imaging processing according to the second embodiment.

(Step S201)
In S201, similarly to S101, scan shooting is performed (S201).

(Step S202)
In S202, monitoring conditions are set. The image display unit 62 displays a setting screen. FIG. 9 is a diagram showing a screen display example of the setting screen. The setting screen 77 displays a tomographic image 78 reconstructed in S201 and a setting area 80 for setting monitoring conditions.

The region-of-interest setting unit 2 a sets a monitoring region 79 on the tomographic image 78. Further, the threshold setting unit 2c sets the auto voice start threshold A ₁ , the auto voice start threshold A ₂ , and the shooting start threshold B in the setting area 80 (S202).

It should be noted that, here, the auto voice start threshold value for A ₁ is a threshold for determining an auto-voice 1 speech at the start of the "Do not move". The auto voice start threshold A ₂ is a threshold for determining the start time of the auto voice 2 “please hold your breath”.

(Step S203)
In S203, similarly to S104, the control unit 3 performs monitoring shooting (S203).

(Step S204)
In S204, the density value calculation unit 2b acquires a monitoring CT value (S204).

The image display unit 62 displays a monitoring screen. FIG. 10 is a diagram illustrating a screen display example of the monitoring screen. In addition to the tomographic image 78, the monitoring region 79, and the setting region 80, the monitoring screen 81 displays a monitoring image 82 that is a tomographic image obtained by monitoring imaging. Note that the timer unit 2f may count the monitoring elapsed time t ₁ or display the monitoring CT value transition graph 83. The monitoring CT value transition graph 83 has a horizontal axis indicating the monitoring elapsed time t ₁ and a vertical axis indicating the monitoring CT value.

(Step S205)
In S205, the monitoring CT value or not automatic voice start threshold _{A 1} is greater than is determined (S107). If the monitoring CT value is the threshold value _{A 1} is larger than for auto voice starts, the process proceeds to S206. If the monitoring CT value is the threshold value _{A 1} is smaller than for auto voice starts, the process returns to S204.

(Step S206)
In S206, the instruction unit 2d utters the auto voice 1 “Please do not move” (S206).

(Step S207)
In S207, the density value calculation unit 2b acquires a monitoring CT value (S207).

(Step S208)
In S208, whether or not monitoring CT value is greater than the auto voice start threshold _{A 2} is determined (S107). If the monitoring CT value is greater than the auto voice start threshold _{A 2,} the process proceeds to S209. If the monitoring CT value is the threshold value _{A 2} is smaller than for auto voice starts, the process returns to S207.

(Step S209)
In S209, the instruction unit 2d utters Auto Voice 2 “Please hold your breath” (S209).

(Step S210)
In S210, the density value calculation unit 2b acquires a monitoring CT value (S210).

(Step S211)
In S211, it is determined whether or not the monitoring CT value is larger than the imaging start threshold B (S211). When the monitoring CT value is larger than the imaging start threshold B, the process proceeds to S212. If the monitoring CT value is smaller than the imaging start threshold B, the process returns to S210.

(Step S212)
In S212, as in S119, the control unit 3 ends the monitoring shooting and starts the main shooting (S212).

According to the present embodiment, a plurality of auto voice start thresholds A ₁ and A ₂ respectively corresponding to a plurality of preparation actions are set. When the monitoring voice CT value is greater than or equal to the auto voice start thresholds A ₁ and A ₂ , the auto voice is uttered in response to the preparation action. Further, when the monitored CT value is larger than the imaging start threshold B, the main imaging is executed. For this reason, the main shooting can be started when the preparatory action is completed, and the main shooting can be performed at an appropriate timing.

<Third embodiment>
In the present embodiment, a monitoring area for the user to determine when to start a preparatory action instruction and a shooting start area for determining the start of main shooting are set.

  Hereinafter, the density value (first density value) of the monitoring area is referred to as monitoring CT value (d), and the density value (second density value) of the imaging start area is referred to as monitoring CT value (c). In the following description, a single preparatory action is instructed by the instruction unit 2d, but there may be a plurality of preparatory actions.

Hereinafter, monitoring imaging according to the third embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing the flow of monitoring shooting processing.
(Step S301)
In S301, as in S101, a tomographic image of the subject is reconstructed (S301).
(Step S302)
In S302, monitoring conditions are set. The image display unit 62 displays a setting screen. FIG. 12 is a diagram showing a screen display example of the setting screen. On the setting screen 84, the tomographic image 85 reconstructed in S301 is displayed.

  The region-of-interest setting unit 2 a sets a monitoring region 86 and an imaging start region 87 on the tomographic image 78. Further, the threshold setting unit 2c sets the auto voice start threshold A and the shooting start threshold B in the setting area 88 (S302).

(Step S303)
In S303, the control unit 3 starts monitoring shooting (S303).

(Step S304)
In S304, the density value calculation unit 2b acquires the monitoring CT value (d) of the monitoring area 86 (S304).

The image display unit 62 displays a monitoring screen. FIG. 13 is a diagram illustrating a screen display example of the monitoring screen. In addition to the tomographic image 85, the monitoring area 86, the imaging start area 87, and the setting area 88, the monitoring screen 89 displays a monitoring image 90 reconstructed by monitoring imaging. Note that the timer unit 2f may count the monitoring elapsed time t ₁ or display the monitoring CT value transition graph 91. In the monitoring CT value transition graph 91, the horizontal axis indicates the monitoring elapsed time t ₁ , the vertical axis indicates the monitoring CT value (c) of the imaging start area 87, and the vertical axis indicates the monitoring CT value (d) of the monitoring area 86.

(Step S305)
In S305, it is determined whether or not the monitored CT value (d) is larger than the auto voice start threshold A (S305). When the monitored CT value (d) is larger than the auto voice start threshold A, the process proceeds to S306. If the monitored CT value (d) is smaller than the auto voice start threshold A, the process returns to S304.

(Step S306)
In S306, the instruction unit 2d utters an auto voice (S306).

(Step S307)
In S307, the density value calculation unit 2b acquires the monitoring CT value (c) of the imaging start area 87 (S307).

(Step S308)
In S308, it is determined whether or not the monitored CT value (c) is larger than the imaging start threshold B (S308). When the monitoring CT value (c) is larger than the imaging start threshold B, the process proceeds to S309. If the monitored CT value (c) is smaller than the auto voice start threshold B, the process returns to S307.

(Step S309)
In S309, as in S119, the control unit 3 ends the monitoring shooting and starts the main shooting (S119).

  According to the present embodiment, when the monitoring CT value (d) in the monitoring area 86 is larger than the auto voice start threshold A, the auto voice is uttered. Further, when the monitoring CT value (d) of the imaging start area 87 is larger than the imaging start threshold B, the main imaging is executed. For this reason, the main shooting can be started when the preparatory action is completed, and the main shooting can be performed at an appropriate timing.

  In the above embodiment, the instruction means for instructing the subject is provided with the auto voice function including the instruction section 2d and the speaker 44. However, the instruction means is not limited to the auto voice, but is applied to the subject. Any means can be used as long as it can notify a preparatory action instruction. For example, a beep sound may be generated to notify the start of the preparatory action, or the LED may blink. Further, a monitor may be installed on the scanner 4 or the like, and an image showing the content of the preparatory action may be displayed on the monitor.

Block diagram showing hardware configuration of X-ray CT apparatus Diagram showing the positional relationship between the X-ray tube and the detector The figure which shows the example of two-dimensional projection data Block diagram showing the configuration of the program executed by the central processing unit The flowchart which shows the flow of the monitoring imaging | photography process concerning 1st embodiment. Figure showing a screen display example of the setting screen Figure showing a screen display example of the monitoring screen The flowchart which shows the flow of the monitoring imaging | photography process concerning 2nd embodiment. Figure showing a screen display example of the setting screen Figure showing a screen display example of the monitoring screen The flowchart which shows the flow of a monitoring imaging | photography process concerning 3rd embodiment. Figure showing a screen display example of the setting screen Figure showing a screen display example of the monitoring screen Flowchart showing the flow of conventional surveillance shooting processing

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray CT apparatus, 2 ... Central processing part, 3 ... Control part, 31 ... X-ray control part, 32 ... Collimator control part, 33 ... Scanner control part, 4 ... Scanner, 41 ... X-ray tube, 42 ... Collimator , 43 ... Detector, 44 ... Speaker, 5 ... Image processing unit, 51 ... Projection data conversion unit, 52 ... Reconstruction processing unit, 6 ... Console, 61 ... Operation unit, 62 ... Image display unit

Claims (3)

An X-ray source that emits X-rays;
An X-ray detector disposed opposite to the X-ray source across the subject and detecting the X-ray and outputting projection data;
Rotating means capable of rotating by mounting the X-ray source and the X-ray detector;
Imaging control means for performing imaging by controlling the X-ray source, the X-ray detector, and the rotating means;
Image processing means for reconstructing a tomographic image of the subject based on the projection data;
Display means for displaying the reconstructed tomographic image;
A region of interest setting means for setting a region of interest on the tomographic image;
Density value calculating means for calculating the density value of the set region of interest;
A threshold for monitoring for determining the start time of an instruction for a preparation action necessary for main imaging for obtaining a contrast-enhanced blood vessel image of the subject into which a contrast medium has been injected, which is greater than the density value at the time of the main imaging Threshold setting means for setting a monitoring threshold that is a low value;
Instruction means for instructing the preparatory action;
With
Prior to the main imaging, the imaging control means performs monitoring imaging for imaging the same part of the subject for a predetermined time and monitoring the density value of the part,
The density value calculating means calculates the density value of the region of interest set on the tomographic image obtained by the monitoring imaging,
When the concentration value is equal to or higher than the monitoring threshold, the instruction means starts an instruction for the preparatory action.
An X-ray CT apparatus characterized by that. The threshold setting means further sets a shooting threshold for determining the start time of the main shooting;
When the density value calculated by the density value calculating unit is equal to or greater than the imaging threshold, the imaging control unit controls the start of actual imaging;
The X-ray CT apparatus according to claim 1. After the instruction of the preparatory action is performed, a monitoring number measuring unit that measures the number of times monitoring shooting is performed by the shooting control unit, or an elapsed time after the shooting control unit starts the monitoring shooting, or the Comprising at least one of time measuring means for measuring an elapsed time since the instruction by the instruction means is performed,
When the number of times of monitoring photographing measured by the monitoring number measuring means is a predetermined number or more, or when the elapsed time since the start of monitoring photographing is a predetermined time or more, or since the instruction by the instruction means When the time is equal to or longer than a predetermined time, the photographing control means controls the start of the main photographing;
The X-ray CT apparatus according to claim 1.

Images