JPS63242239A - Ecg gate x-ray ct apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ECG-gated X-ray CTM device that performs scanning of the heart using heartbeat synchronization.

(Prior Art) As an example of an X-ray CT apparatus, one having the configuration shown in FIG. 7 is known. This device has an X-ray tube 2 and a detector 3 that are integrally connected around the subject 1, and the X-ray tube 2 rotates around the subject 1 while emitting X-rays and detecting them. Vessel 3
X-ray absorption rate data regarding the subject 1 is collected. This X-ray CT device is called a third generation CT, and X-ray radiation is performed from the X-ray tube 2 at the position (data sampling position) over a fan angle of θ to obtain fan data. By rotating the X-ray tube 2 over a range of at least 180°+θ°, data is collected by a so-called source fan method, and image reconstruction is performed based on this source fan.

On the other hand, as an example of an X-ray CT apparatus, one having the configuration shown in FIG. 8 has been described.

This device has an X-ray tube 2 and a detector 3 arranged around the subject 1, and only the X-ray tube 2 rotates around the subject 1 while emitting X-rays. Fan data of fan angle O is set by 1q. This X-ray CT
The device is called a 4th generation CT, and like the 3rd generation CT, data collection is performed using the source fan method. By the way, when focusing on one detector 3a in this fourth generation CT, this detector 3a collects data over the time period during which the X-ray tube 2 rotates from the P1 position to the P2 position, as shown in FIG. This data collection area is referred to as the detector fan in contrast to the source fan. Of course, in the fourth generation CT, the source fan can be converted into a detector fan.

The source fan data or detector fan data 1q obtained by performing X-ray exposure in this manner is called view data. Detector fan data has advantages over source fan data, such as higher detection efficiency because a larger number of data samples can be taken, and less influence on reconstructed images because variations in the characteristics of individual data are averaged out. are doing. For these reasons, the fourth
In the generation CH, compared to the third generation CT, data collection is performed by a source fan method, but image reconstruction is performed using detector fan data.

By the way, when performing a scan targeting the heart using such an X-ray CT device, a so-called force-diac scan, an electrocardiogram (ECG) is used to observe the movement of the heart at any given time during one heartbeat. In other words, as shown in FIG. 10, the ECG waveform is divided into ten sections, for example, and a gate is provided in each section to obtain a curved gate image. In this case, to make the explanation easier to understand, the performance
If a line CT device is prepared and a subject is scanned at 1 heartbeat/second, the same ECG time phase will be obtained four times in one scan (one rotation) as shown in FIG.

That is, Dl, D2.

Four pieces of data, D3 and D4, will be 1q.

If such a scanning operation is applied to 1q of view data of the 3rd generation CH shown in Fig. 7, if the number of data sampling is fixed at 100Of, the time required to obtain the view data will be 4 m5 (4 seconds). /1000).To perform image reconstruction, continuous view data is required due to the principles of CT, so by repeating the scan multiple times, temporally shifted data D1 as shown in Figure 12 is obtained. It is necessary to obtain a plurality of data from D4 to fill in the data on the entire circumference.

(Problem to be solved by the invention) By the way, when filling the view data continuously, in the third generation CT, data can be obtained by one scan in about 4 ms as mentioned above, so it is relatively easy to fill all the necessary view data. Data can be collected.

However, in 4th generation CT, detector fan data is used as view data, so the time required to obtain view data as shown in Figure 9 is relatively long, several hundred meters per scan. There is a problem that only a part of the data can be 1Q.

The present invention was made in response to such problems, and an object of the present invention is to provide an ECG gated X-ray CT apparatus that easily obtains the view data necessary for reconstruction even in the case of 4th generation CT. be.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides means for scanning a subject multiple times using an ECG gate to collect multiple pieces of data; The present invention is characterized by comprising means for completing one continuous detector fan data by collecting data included in the gate range.

(Function) One detector fan data is completed by collecting the data included in the gate period from among the data collected by scanning the object multiple times, and feathering adjacent data as necessary. be done. Image reconstruction becomes possible by obtaining such detector fan data for all detectors.

(Embodiment) FIG. 1 is a block diagram showing an ECG gated X-ray CT apparatus according to an embodiment of the present invention. The X-ray tube 2 emits X-rays while rotating around the subject 1. The image display section operation section 7 is composed of an operation console, equipped with various operation switches, and controls the system control section 8.

The system control section 8 includes an X-ray control section 91, a mechanism control section 10, a data collection section 11. It controls the arithmetic control section 12.

The X-ray control unit 9 controls the timing of X-ray exposure of the X-ray tube 2 and the like. The mechanism control section 10 controls the mechanism of the pedestal section 6. The electrocardiograph 13 records an electrocardiogram (ECG) of the heart of the subject 1.
) to measure the following. The data collection unit 11 is
It is used to collect data in accordance with the scanning of the wire tube 2, and in the case of the present invention, in particular, data collection is performed to continuously complete view data, that is, detector fan data obtained by the ECG @ period.

That is, data included in a preset gate range is collected by repeating the scan multiple times.

The arithmetic control unit 12 performs arithmetic processing to complete continuous detector fan data based on the collected data, and performs feathering processing between adjacent data as necessary to create smooth continuous data. do. Also, based on the ROI designation of the image display unit operation unit 7, this arithmetic control unit 11 performs 7 ethering processing to create data on the inside and outside of parts that change significantly over time among the collected data. Perform the action to complete the task. The detector fan data calculated in this manner undergoes image reconstruction for all detectors. The obtained image information is stored on storage disk 1.
4, etc., and is taken out and displayed on a display (not shown) as needed.

Next, the operation of this embodiment will be explained.

By rotating the X-ray tube 2 and performing one scan, detector fan data as shown in FIG. 2 can be obtained. If we perform a curve scan using an ECG gate that divides one heartbeat into several parts, the probability is that the same time phase data D obtained during the gate period Tc in the detector fan data in Fig. 2 will be 4 times smaller. Therefore, it is necessary to perform the scan multiple times. Even if multiple scans are performed, the same time phase data included during the gate period is often limited to random scan data as shown in FIG. 3 based on the probability. Therefore, among the data collected by multiple scans, data included in the gate period Tc, for example, data O1.
, Do, and Dt to complete one continuous detector fan data. In this case, in order to smooth the connection between multiple data, the level 11 between adjacent data, for example, Dz and Do, as shown in FIG.
, L2 are feathered to smooth the data level. Further, if there is a missing part in FIG. 5 between adjacent data Dz and Do, either one is extended as shown by the dotted line and feathering processing is performed in the same way.

As a result, data missing portions are corrected and connected portions are smoothed, so that unnatural connections do not occur.

By performing such connection processing and feathering processing on all the detectors that make up the detaffer fan data, and performing image reconstruction using the detector fan, a curve detection gate synchronized with the ECG period phase is created. You can get the image.

In addition, based on the data obtained through the curve scan, we designated an ROI as shown in Figure 6 for areas that change particularly rapidly over time, and compared the data collected within this ROI with the R
Detector fan data can be completed by connecting data collected outside the OI. In this case, for data outside the ROI, the average value of the scan data of the number of throws without gates can be used, and the R
The connections between internal and external data can be smoothed by performing feathering processing as described above.

According to this type of curve scan, when image reconstruction is performed using the detector fan method as in 4th generation CT, even if it takes a relatively long time to reconstruct the detector fan data, Since detecting data can be easily obtained, a clear curved gate image can be obtained.

The X-ray emitting means of the X-ray tube can be applied to either pulsed X-rays or continuous X-rays, and the structure of the 4th generation CT is such that the X-ray tube is located either inside or outside the detector. But it can be applied as well.

[Effects of the Invention] As described above, according to the present invention, when performing image reconstruction using detector fan data, continuous detector fan data can be completed by collecting data included in the gate period. Therefore, you can easily move up the curve gate image by one level.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an ECG gated X-ray CT apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams showing an example of data collection according to this embodiment, and FIGS. A schematic diagram showing an example of feathering processing, FIG. 6 is an explanatory diagram showing an example of data collection in another embodiment of the present invention, and FIG. 7 is a third generation CT
FIGS. 8 and 9 are schematic diagrams showing the fourth generation CT, FIG. 10 is an ECG waveform diagram, and FIGS. 11 and 1.
FIG. 2 is an explanatory diagram showing an example of data collection by ECG gated cardiac scan. DESCRIPTION OF SYMBOLS 1... Subject, 2... X-ray tube, 3... X-ray detector, 6... Frame part, 11... Data collection part, 12...
- Arithmetic control unit, 13... electrocardiograph. Agent Patent Attorney Nori Chika Ken Shu
Ogotsu Unemployment 5 Figure 6 Figure 7 Figure 9

Claims (3)

[Claims] (1) In an ECG gate X-ray CT device that reconstructs source fan data obtained by rotating the X-ray tube around the subject into detector fan data, the subject is scanned multiple times by the ECG gate and 1. An ECG gated X-ray CT apparatus comprising: means for collecting data included in a gate period; and means for completing one continuous detector fan data by collecting data included in a gate period among a plurality of data. (2) The ECG gated X-ray CT according to claim 1, wherein the means for completing one detector fan data performs feathering processing on adjacent pieces of data among a plurality of pieces of data included in the gate range. Device. (3) E according to claim 1, which specifies the ROI in a region that changes significantly over time based on the collected data.
CG gate X-ray CT device.