JPH01207038A - Ct apparatus equipped with contrast medium density control function - Google Patents

Abstract

PURPOSE:To automatically and properly inject a contrast medium, by providing an X-ray CT, a contrast medium injector, a means for comparing the reference CT value at a reference place with a measured CT value and a control means for controlling the injector on the basis of the comparing result. CONSTITUTION:A measuring interface 2 and an operator 3 take in measured data to obtain a CT image and a CRT 5 displays said image as a tomographic image through an image display circuit 4. The CRT 5 displays the CT value of an object to be compared for the injection by an injector other than the display of the measured tomographic image. The operator 3 has function outputting two CT values. A contrast medium injector (injector) 10 receives a contrast medium injection order through an interface 9 to automatically inject a contrast medium. This order is performed by a CPU 1. When a reference CT value is larger than a measured CT value, the injection of a contrast medium is immediately performed and, contrarily, when the measured CT value is larger, the injection of the contrast medium is stopped. By this method, the proper injection of the contrast medium is properly performed and a CT tomographic image accompanied by contrast effect due to the contrast medium is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a CT apparatus with a contrast agent concentration adjustment function.

[Conventional technology]

In order to obtain clear CT images, there is a method of injecting a contrast agent into the subject's body before imaging with a CT device. The literature on this conventional example includes "rcT Scanner" (see page 215, Corona Publishing, published in 1974, edited by Iwai).

In this conventional example, a CT scan is performed after intravenously injecting a contrast medium. According to this conventional example, the absorption coefficient of a lesion such as a brain tumor or blood vessel disorder is increased, and a clear image can be extracted.

[Problem to be solved by the invention]

In the conventional example, the contrast medium injection and the CT apparatus are not linked, and there is a problem that the CT apparatus and the contrast medium injection lack coordination. In particular, now that contrast agent injectors have become widespread, it is necessary to link the contrast agent injector with a CT apparatus. Conventionally, in many cases, an operator of a CT apparatus uses an external controller of a contrast agent injector to inject the contrast agent at a timing determined by the operator. Also, depending on the type of syringe, even if there is a mode for adding a contrast agent, it has not been possible to link it with a CT device. Therefore,
If the contrast medium injection conditions initially set are not optimal, the contrast effect may be too little or too strong, causing artifacts or worsening the patient's mood. Injecting a contrast medium requires valuable knowledge and sensitivity regarding the conditions and timing of injection, and is often performed by experienced personnel.

An object of the present invention is to provide a CT apparatus that automatically makes it possible to properly inject a contrast medium without relying on the knowledge and sensitivity of an experienced person.

[Means to solve the problem]

In addition to an X-ray CT and a contrast agent injector, the present invention also provides means for comparing the magnitude of a reference CT value and a measured CT value at a reference location;
A control means for controlling the syringe based on the comparison results was provided.

[Effect]

In the present invention, contrast agent injection can be controlled by the control system.

In particular, it is possible to determine the amount of contrast medium to be injected by looking at the reference CT value and the measured CT value, thereby contributing to the determination of the next amount of contrast medium to be injected. That is, the CT value of the image immediately after contrast medium injection is read, and the contrast effect due to individual differences in the subject is constantly checked. If the contrast effect is low, additional contrast agent is automatically injected through the control system.

Furthermore, if the expected contrast effect appears before the additional injection amount is completely injected, the injection is stopped. This prevents artifacts from occurring due to too strong contrast, ensures proper injection of contrast medium into the subject, and simplifies the contrast medium injection operation.

[Example] FIG. 1 shows an example diagram of the present invention. FIG. 2 is an operation time chart.

The CPUI controls the main body of the CT apparatus (not shown).

The CT apparatus main body includes both the mechanical system and drive control system of the CT apparatus. It does not include the system for collecting and processing CT measurement data.

A measurement interface 2 and a calculation (various pre-processing, image reconstruction processing) device 3 take in measurement data and obtain both CT images. Both CT images are temporarily stored on the magnetic disk 7 via the interface 6. This stored CT image or the CT image obtained by the calculator 3 is displayed as a tomographic image via the image display circuit 4.

More importantly, in addition to displaying the measured tomographic image, the CRT 5 displays the comparison target OCT value for injector injection. The CT value to be compared refers to the designated CT value of a reference location of the subject and the measured CT value obtained from the reference location. The designated CT value is the desired CT value given from the external operation unit (including the keyboard) 8, and the measured CT value is the actually measured CT value obtained from the calculator 3. Naturally, the CT value is the value before the code conversion to the tissue of the subject, and the tomographic image is the value of this CT value.
This is data after conversion of the code into the tissue of the subject. Code conversion refers to CT value → gradation conversion, which determines how many gradations to display for skin and how many gradations to display for bones.

Conversely, the arithmetic unit 3 has a function of outputting two CT values.

The contrast medium injector (injector NO receives a contrast medium injection command (including the injection amount) via the interface 9 and automatically injects the contrast medium. This command is performed by crt+t.

Note that the transmission line 20 is a common bus, and various signals are transmitted via this common bus.

Let us explain the overall operation using the operation time chart shown in FIG.

First, before starting the main measurement, the CT performs CT measurement under instructions from the CPUI, reconstructs an image, and obtains a preliminary CT value. And the region (ROI) where you want to check the CT value
is set, the CT value of the ROI region is displayed on the CRTS, and the operator, looking at the displayed content, sets a target reference CT value via the operation system 8.

After setting this reference CT value, the operation starts as shown in the operation time chart of FIG. First, a measurement standby period is set. Within this period, CT scans are performed several times. In the figure, n times of CT scans were performed. Here, a CT scan refers to irradiating a subject with X-rays while circling the subject in order to obtain one tomographic image.

A CT tomographic image is obtained for each scan. The processing time to obtain one tomographic image from measurement data obtained by one scan is at the same time as the end of the measurement or within several seconds. Therefore,
As shown in the figure, CT tomographic image #1 from the first scan
can be displayed during the second scan.

On the other hand, the period during which the injector 10 is controlled is limited to the scan period during which X-rays are actually emitted and measured. The injector 10 is operable only during the measurement standby period, and therefore the injector 9 is always ready and waiting under the direction of the interface 9 during the standby period.

FIG. 2 shows two examples of operations. Operation 1 is an example in which the contrast agent injection effect appears gradually, and is an example of a liver OCT tomogram. Operation 2 is an example in which the contrast agent injection effect appears quickly, and is an example of blood vessels and kidneys.

In operation 1, a continuous injection command for the syringe 10 is given including three scan periods. When obtaining CT tomograms from the first and second scans, the base ICT value and measured C
The reference CT value is displayed on the CRT 5, and the magnitude relationship between the two is observed (comparison is made with an x mark). If the reference CT value is large, the closing command is issued continuously. As a result of the third scan, the measured CT value in the ROI region has become large, so the injection command to the injector 10 is stopped. 4th time.

The fifth scan also shows that the measured CT value is
Since the value is larger than the value C'['', no injection command is issued to the injector 10.

When observing the heart or blood vessels, the contrast effect appears quickly and flows out quickly, and if the contrast agent is too thick, artifacts occur, requiring delicate control of the contrast agent. Therefore, in operation 2, the injection by the injector 10 is limited to only during the scan period, and continuous injection is not allowed. That is, an injection command is given to the injector 10 in synchronization with the first and second scans. A CT tomographic image from this second scan is obtained, and a measured CT value in the Rot region is obtained, and the measured CT value and the reference CT value are displayed together to see their magnitude relationship. In the figure, the reference CT value has not yet been reached. However, looking at the deviation between the two C'T values, it is considered that the reference CT value will be exceeded at the time of the next third scan, so the third contrast medium is not injected. Then, a comparison is made with the CT value after the third scan, and it can be seen that a measured CT value larger than the reference CT value was obtained. The same procedure is repeated below. Normally, in the vascular system, the contrast effect appears about 3 seconds after contrast injection, and the effect lasts about 2 to 4 seconds. Therefore, the measurement sequence is 3 to 4.
If the injection is carried out every second and the amount of contrast medium injected is optimized, it becomes possible to constantly maintain the effect of the contrast medium within the blood vessel at a nearly constant level.

It should be noted that the period from the inputting command to the actual loading operation of the container 10 is quick, and as soon as the loading command is given, the loading device 10 responds and performs the loading operation.

As is clear from the above operations 1 and 2, if the reference CT value is larger than the measured CT value, the contrast medium is immediately injected, and conversely, if the measured CT value is large, the contrast medium is stopped. As a result, a proper contrast medium is injected, and a CT tomographic image with the contrast effect of this contrast medium is obtained.

When injecting a contrast medium, there are two types: one is to reduce the amount of injection per hour and inject over a long period of time, and the other is to reduce the amount of injection per hour and inject several times over a short period of time.
There is. Action l is suitable for the former and action 2 is suitable for the latter.

In the above actual example, the reference CT value and the measured CT value are stored on the CRT.
We decided to display both the value and the value, and to specify the operation of the dosing device based on the operator's observation. However, without displaying it on the CRT, the comparison may be made automatically within the arithmetic unit 3, and if injection is necessary, an injection instruction may be automatically given. This can be solved with software. Alternatively, the CPU 1 may issue this automatic determination and input command. When making these automatic judgments and automatic commands, specify the ROI region as an address1, and select the CT value of the ROI region among the measured CT values.
Read the value and make a decision.

Furthermore, since the operation pattern of the dosing device can be changed depending on the condition of the CT value, it is possible to operate it in the pattern of operation 2 first, and then to operate it in the pattern of operation 1 thereafter. Depending on the CT value measured inside the body, a contrast medium can also be injected, and it is also possible to completely stop the injector if the CT value exceeds the standard CT value. In order to meet these various demands, several operation patterns may be set (protocolized) depending on the measurement mode, and one may be selected as appropriate.

Furthermore, although the base $CT value is fixed, it is also possible to curve the base CT value according to the passage of time. FIG. 3 shows an example.

〔Effect of the invention〕

According to the present invention, since the contrast agent injector is operated in conjunction with the X-ray CT, the contrast agent can be automatically injected using the injector depending on the magnitude relationship between the reference CT value and the measured CT value. Ta. This made it possible to properly inject the contrast medium, reduce artifacts, and reduce the burden on the operator.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, FIG. 2 is an operation time chart thereof, and FIG. 3 is an example of a reference CT value. ■...CPU (processor), 3...Arithmetic unit, 1
0...Contrast medium injector (injector). Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An X-ray CT, a contrast agent injector, a means for comparing the CT value measured at a reference point by the X-ray CT with a reference CT value at the reference location, and a reference CT value as a result of the comparison. control means for controlling the contrast medium injection by controlling the contrast medium injector when the reference CT value is large, and for controlling the contrast medium injection by the contrast medium injector when the reference CT value is small; CT device with contrast agent concentration adjustment function.