JPH03272748A - X-ray ct device - Google Patents

Abstract

PURPOSE:To acquire a reformed image without being affected by the direction of a testee on a bed and with no deterioration of an image in quality by setting a starting angle for given image reformation free from a photographing starting angle, reading projection data out of a memory means, and thereby processing an image reforming operation so as to acquire the reformed image. CONSTITUTION:When, for example, a testee is photographed while being directed to the left by 90 deg., the angle of 90 deg. corresponding to the direction of the testee 13 is set up in advance before photographing is started, the aforesaid angle is held temporarily as a reformation starting angle. Both a X-ray tube 11 and a detector 14 are rotated at the time of photographing, photographing data acquired in order is temporarily stored in a data memory. In this case, address control is executed in such a way that data for a reforming angle in which photographing data is retained, comes first, data acquired at the angle of 90 deg. therefore comes first out of stored photographing data. Data is therefore is lined up in order of [90 deg. through 360 deg. (0 deg.)]+[0 deg. through 90 deg.]. When the reforming operation is processed by the use of stored photographing data later on, a reverse projection image where the testee is directed upward is shown on a display section 15.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to X-ray CT, which obtains tomographic images of a subject using
Regarding equipment.

(Prior art) The R/R type (third generation) X1iCT device eliminates translational scanning by using fan-shaped X-rays (fan beam) with a large spread angle that covers the entire imaging area including the subject. This is a system that allows imaging using only rotational motion, and both the X-ray tube and detector are rotated and scanned. Figure 2 (1)
1 shows a scanning start state of this R/R type X-ray CT apparatus, 11 is an X-ray tube, 12 is an imaging area, 13 is a subject, and 14 is a detector consisting of a group of detection elements. On the bed (
The starting angle when photographing the subject 13 (not shown) is 00.
In this case, the photographic data obtained by photographing becomes as shown in FIG. It is read out, reconstructed and processed, and then transferred to the CRT.
A back-projection image as shown in FIG. 2(3) can be obtained on the display unit 15 such as the above.

Here, the starting angle and back projection starting angle when shooting are:
Due to the structure of the device, both of them are fixed to match in advance by its hardware, and as shown in the figure, the orientation of the image obtained on the display unit 15 is determined by the orientation of the subject 13 on the bed at the time of imaging.

(Problem to be Solved by the Invention) As described above, since the orientation of the subject 13 on the bed at the time of imaging becomes the orientation of the image obtained on the display section t5, the orientation of the subject 18 at the time of imaging depends on its health condition, etc. When the orientation on the bed is limited, the orientation of the image obtained on the display unit 15 is also limited, making it difficult to obtain an image in an orientation suitable for diagnosis, making diagnosis difficult. There are cases.

In order to solve this problem, it may be possible to rotate the obtained reconstructed image in the post-processing stage to an orientation suitable for diagnosis, but this image rotation process can cause a significant deterioration in image quality. This is not practical as it may impede diagnosis.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to obtain the desired image without being affected by the orientation of the subject on the bed during imaging and without causing deterioration in image quality. Nose that allows you to obtain reconstructed images in any orientation≠
An object of the present invention is to provide an X-ray CT apparatus.

[Structure of the Invention (Means and Effects for Solving the Problem) That is, the present invention stores photographic data obtained by photographing, and stores the photographic data according to an arbitrary starting angle of image reconstruction independent of the photographing starting angle. This system performs image reconstruction calculation processing on the photographed data to obtain a reconstructed image, regardless of the orientation of the subject on the bed at the time of imaging, and without deteriorating image quality, making it easier to diagnose. A reconstructed image can be obtained at an angle suitable for

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 (1) shows the scanning start state of the R/R type XICT device, and is basically the same as that in Figure 2 (1), so the same parts are given the same reference numerals. Therefore, the explanation will be omitted.

Here again, if the starting angle when photographing the subject 13 on the bed (not shown) is set to 00, the subject 13 cannot face upwards due to its health condition, and for example, as shown in the figure, the starting angle is 90'' to the left. It is assumed that imaging is performed with the object 13 facing the direction of the object.Before imaging, the operator sets an angle r90J corresponding to the orientation of the subject 13, and the set angle is temporarily held as the reconstruction start angle. X-ray tube 1 during imaging.
Photographic data sequentially obtained by rotating the detector 1 and the detector 14 is temporarily stored in a data memory (not shown). When storing this data in the data memory, the address of the photographic data is controlled so that the data of the reconstruction angle held above is at the beginning, and the photographic data stored in the memory is shown in Fig. 1 (2). 1:l:r90'J data at the beginning "901'~360m(0")"
~9oa''. After obtaining the imaging data for the subject weight 3 in this way, when reconstruction calculation processing is performed using the imaging data stored in the memory, the display unit 15 shows that the subject I3 is displayed as shown in FIG. 1 (3). A back-projected image can be obtained with the device facing upward.

In addition, in the description of the above embodiment, the subject 13 is located at "90" on the left side of the figure.
Although an example was shown in which the photograph was taken with the subject facing in the direction of ``'', this angle can be set arbitrarily. By setting this arbitrary angle rn' (0≦n≦360) J, the photographic data stored in the data memory will be rn' ~ 360' (0°) J +ro" ~ n"
The order of the angle is J.

Further, in the above embodiment, the photographic data obtained by photographing is stored in the data memory in an address order according to the set reconstruction start angle, and the photographic data stored in this data memory is sequentially read out to obtain a reconstructed image. However, in addition to the shooting data, the set reconstruction start angle is also stored separately, and the shooting data is stored in the same order as it was obtained during shooting, so that when reconstructing, the order based on the reconstruction start angle is stored. It is also conceivable to read the photographic data and obtain a reconstructed image.

Furthermore, as a storage means for storing photographic data, not only the data memory described above but also a hard disk device, an optical disk device, etc. may be used.

Further, the present invention can be applied to a fourth generation X-ray CT device in which the detector is fixed and only the X-ray tube rotates, and a fifth generation X@CT device in which both the detector and the X-ray tube are fixed.

[Effects of the Invention] As described above, according to the present invention, photographic data obtained by photographing is stored, and an image of the photographic data is stored according to an arbitrary image reconstruction start angle independent of the photographing start angle. Since the reconstruction calculation process is executed to obtain a reconstructed image, regardless of the orientation of the subject on the bed at the time of imaging, there is no deterioration in image quality, and the image can be reconstructed at an angle more suitable for diagnosis. It is possible to provide an X-ray CT apparatus that can obtain constituent images and perform accurate diagnosis without placing a burden on the diagnostician.

[Brief explanation of drawings]

FIG. 1 (1) is a diagram showing a photographing state of an embodiment of the present invention;
Figure 1 (2) is a diagram showing the storage state of imaging data, Figure 1 (3) is a diagram showing the obtained reconstructed image, and Figure 2 (1) is a diagram of a conventional R/R type X-ray CT device. Figure 2 (2) is a diagram showing the recording state of photographic data, and Figure 2 (2) is a diagram showing the recording state of photographic data.
3) is a diagram showing the obtained reconstructed image. DESCRIPTION OF SYMBOLS 11... X-ray tube, 12... Imaging area, 13... Subject, 14... Detector, 15... Display section.

Claims (1)

[Scope of Claims] A storage means for storing projection data obtained by imaging; a setting means for setting a starting angle for arbitrary image reconstruction independent of the imaging starting angle; and a starting angle set by the setting means. An X-ray CT apparatus comprising: a reconstruction calculation means for reading projection data from the storage means according to the angle and performing image reconstruction calculation processing to obtain a reconstructed image.