JP2544621Y2 - X-ray CT system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus, and more particularly, to an X-ray CT apparatus which corrects X-ray data acquired by a data acquisition system based on data of a calibration file to generate an image. The present invention relates to a line CT apparatus.

[0002]

2. Description of the Related Art An X-ray CT apparatus generates an image by correcting X-ray data acquired by a data acquisition system based on data in a calibration file. The service file is created by a service person prior to use by the user.

The data of the calibration file is adjusted every day by warm-up data obtained by performing a warm-up scan by a user.

For example, each of the calibration files
Air-DAS (data acquisition s
The data Cth for the (ystem) count is adjusted as follows: Cth after adjustment = (W10 / C10) · Cth where C10 is thi of the calibration file
Air-DAS count data at ckness = 10 mm, W
10 is the warm-up data of the Air-DAS count when the thickness = 10 mm.

[0005] Such adjustment is made because the data Cth and the warm-up data W10 change according to the state of the data acquisition system such as the X-ray tube, the filter, and the detector. This is done to eliminate errors due to changes.

However, the data Cth and the warm-up data W10 also depend on the difference in X-ray tube temperature during data collection.
Therefore, it is desirable that the X-ray tube temperatures at the time of creating the calibration file and at the time of acquiring the warm-up data match as much as possible.

Therefore, at the time of acquiring the warm-up data, the user executes a certain number of scans every day from the cold state of the X-ray tube (the X-ray tube temperature at this time is Tw).
And warm-up data has been obtained. That is, the warm-up data is acquired at a substantially constant X-ray tube temperature Tw every day.

When a calibration file is created, the number of scans considered to be substantially equal to the X-ray tube temperature Tw is calculated by a serviceman based on experience, and after that scan is executed (the X-ray tube temperature at this time) Is Tc), and a calibration file is created.

[0009]

In the above conventional X-ray CT apparatus, a calibration file is created based on the experience of a service person. For this reason, there is a problem that the accuracy of the created calibration file differs depending on the service person.

Further, since there is no guarantee that the X-ray tube temperature Tc and the X-ray tube temperature Tw match, there is a problem that the adjustment of the calibration file includes an error due to the difference in the X-ray tube temperature.

Therefore, an object of the present invention is to make it possible to create a calibration file with uniform accuracy regardless of individual service personnel and to reduce errors caused by differences in X-ray tube temperatures included in adjustment of the calibration file. An object of the present invention is to provide a possible X-ray CT apparatus.

[0012]

SUMMARY OF THE INVENTION This invention is based on the X
Calibration data for correcting line data
X-ray CT apparatus having an X-ray tube temperature of a predetermined temperature
The number of scans or cooling time required to reach
Calculation means and scan or cool
After performing calibration, the calibration data
And a means for creating .

[0013]

In the X-ray CT apparatus of the present invention, the number of scans / cooling time calculating means calculates the number of scans / cooling time required for the X-ray tube temperature to reach a predetermined temperature.
After executing the scan / cooling based on the calculation result, the calibration means creates a calibration file. For this reason, it is possible to create a calibration file with uniform accuracy regardless of the experience of each service person.

After executing the scan / cooling based on the calculation result, the warm-up means obtains the warm-up data. Therefore, the creation of a calibration file and the acquisition of warm-up data
Since the setting of the tube temperature can be made the same,
An error caused by a difference in X-ray tube temperature included in adjustment of the calibration file can be reduced.

Further, by setting the predetermined temperature to the X-ray tube temperature at the time of executing a normal scan, it is possible to create a highly accurate calibration file according to the normal scan.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the embodiment shown in the drawings. Note that this does not limit the present invention. FIG. 1 is a block diagram of a main part of an embodiment of the X-ray CT apparatus according to the present invention. The X-ray CT apparatus 1 is controlled by a scan control unit 2 and a data collection unit 3
Scan with. The data acquisition unit 3 includes, for example, an X-ray tube X, a filter F, and a detector D.

The X-ray CT apparatus 1 calculates the number of scans / cooling time for calculating the number of scans / cooling time required for the X-ray tube temperature to reach a predetermined temperature.
A calibration unit 5 for creating a calibration file after executing scan / cooling based on the calculation result, and a warm-up unit 6 for acquiring warm-up data after executing scan / cooling based on the calculation result. I have it.

Next, the creation of a calibration file will be described with reference to the flowchart of FIG.

In step S 1, in response to a calibration file creation request from the operator, the calibration unit 5 outputs a scan number / cooling time calculation request to the scan number / cooling time calculation unit 4.

In step S2, in response to the calculation request for the number of scans / cooling time, the number of scans / cooling time calculator 4 sets the current X-ray tube temperature T to a normal value as shown in the flowchart of FIG. Calculate the number of scans / cooling time required to raise / lower the X-ray tube temperature Ts when performing the scan.

That is, in step S21, the number of scans is initialized to M = 0 and the cooling time is initialized to zero. In step S22, the current X-ray tube temperature T is detected and compared with the X-ray tube temperature Ts at the time of executing a normal scan.

When the X-ray tube temperature T ≧ X-ray tube temperature Ts,
In step S23, the X-ray tube temperature Ts
Calculate the cooling time required to descend to Then, the calculation result is output to the calibration unit 5. However, when X-ray tube temperature T = X-ray tube temperature Ts,
Cooling time = 0 remains.

If the X-ray tube temperature T <X-ray tube temperature Ts, then in step S24, the number of scans is set to M = M + 1, and the flow advances to step S25.

In step S25, the X-ray tube temperature Tm after scanning is calculated. In step S26, the calculated X-ray tube temperature Tm after the scan is compared with the X-ray tube temperature Ts.

When the X-ray tube temperature Tm ≧ X-ray tube temperature Ts, the number of scans M is output to the calibration unit 5. When X-ray tube temperature Tm <X-ray tube temperature Ts,
In step S27, considering the delay until the next scan, the X-ray tube temperature after the delay is calculated. Then, steps S24 to S24 are repeated, and the X-ray tube temperature T after the scan is set.
When m ≧ X-ray tube temperature Ts, the number of scans M is output to the calibration unit 5.

Returning to FIG. 2, in step S3, upon receiving the calculation result from the number of scans / cooling time calculation unit 4 as described above, the calibration unit 5 sends a scan / scan based on the calculation result to the scan control unit 2. Outputs a cooling execution request.

In step S4, upon receiving a scan / cooling execution request based on the calculation result, the scan control unit 2 causes the data collection unit 3 to execute the scan / cooling based on the calculation result.
Let the cooling run.

In step S5, after executing the scan / cooling based on the above calculation results, that is, the X-ray tube temperature T when the X-ray tube temperature is set to perform a normal scan.
When it becomes almost equal to s, the calibration unit 5 creates a calibration file.

In the adjustment of the calibration file,
In step S1, upon receiving a calibration file adjustment request from the operator, the warm-up unit 6 outputs a request for calculating the number of scans / cooling time to the number of scans / cooling time calculation unit 4.

In steps S2 to S4, the warm-up unit 6 performs the same operation as the calibration unit 5 in creating a calibration file.

Then, in step S5, after executing the scan / cooling based on the calculation result, the warm-up unit 6 acquires the warm-up data and adjusts the calibration file.

[0032]

According to the X-ray CT apparatus of the present invention, it is possible to create a calibration file with uniform accuracy regardless of the experience of each service person.

Since the creation of the calibration file and the acquisition of the warm-up data can be performed with the same setting of the X-ray tube temperature, the error caused by the difference in the X-ray tube temperature included in the adjustment of the calibration file is reduced. . For this reason, the image quality is improved.

Further, by creating the calibration file and obtaining the warm-up data by setting the X-ray tube temperature at the time of executing a normal scan, a highly accurate calibration file conforming to the normal scan can be obtained. Can be created.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of an embodiment of an X-ray CT apparatus according to the present invention.

FIG. 2 is a flowchart for creating and adjusting a calibration file according to the apparatus of FIG. 1;

FIG. 3 is a flowchart illustrating an operation of a scan number / cooling time calculation unit of the apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray CT apparatus 2 Scan control part 3 Data acquisition part 4 Number of scans / cooling time calculation part 5 Calibration part 6 Warm-up part

Claims (1)

(57) [Scope of request for utility model registration] 1. A key for correcting collected X-ray data.
X-ray CT system with calibration data
The number of scans required for the X-ray tube temperature to reach a predetermined temperature
Or a means to calculate the cooling time and the calculation result
After scanning or cooling by
An X-ray CT apparatus, comprising: means for creating relation data.