JP3919777B2 - X-ray CT system - Google Patents

Description

  The present invention relates to an X-ray CT (Computed Tomography) apparatus that generates projection data, and more specifically, an X-ray capable of generating projection data such as 3D (Dimension) data and ZP (Zntensity Projection) data at high speed. The present invention relates to a CT apparatus.

FIG. 22 is a configuration diagram of an example of a conventional X-ray CT apparatus.
The X-ray CT apparatus 500 includes a scanner device 1, a processing device 52, a mass storage device 3 (for example, a hard disk device), a display monitor 4, and an input device 5.

  The scanner device 1 moves the X-ray tube and the detector relative to the subject along one axis (usually coincides with the body axis of the subject), stops at the cross-sectional position on the axis, Rotate the x-ray tube and detector around the axis to collect all the view data needed to generate the image data. In some cases, only the X-ray tube is rotated and the detector is not rotated.

  The processing device 52 includes a data acquisition unit 2a, an image data generation unit 2b, a volume data generation unit 2g, a projection data generation unit 2h, and an image display unit 2e.

FIG. 23 is a flowchart of the processing of the data acquisition unit 2a. The flowchart is shown by PAD (Program Analysis Diagram).
In step V1, as shown in FIG. 24, the operator sets a plurality of cross-sectional positions S1 to S6 on the Z axis (the X-ray tube and the detector are moved relative to the subject along this axis). To do.
In Step V2, the X-ray tube and the detector are moved relative to the subject along the Z axis, and Step V3 is repeated for each of the cross-sectional positions S1,. Note that relative movement means both when the subject is stationary and the X-ray tube and the detector are moved along the Z axis, and when both the X-ray tube and the detector are stationary and the subject is moved along the Z axis. It means to include.
In Step V3, the view is changed by rotating the X-ray tube and the detector around the Z axis (around the subject), and Step V4 is repeated for each view.
In step V4, data is acquired from the detector.
As described above, all view data (hereinafter referred to as a data set) necessary for generating image data at each of the cross-sectional positions S1,..., S6 is obtained.

FIG. 25 is a flowchart of the processing of the image data generation unit 2b.
In step J1, steps J2 ′ to J4 are repeated for each data set at each of the cross-sectional positions S1,.
In step J2 ′, image reconstruction calculation (back projection calculation) is performed on the data set to obtain image data. Then, the image data is stored in the mass storage device 3.
In step J3, it is determined whether the operator has instructed to display a cross-sectional image. If the operator has instructed, the process proceeds to Step J4. If the operator has not instructed, the process returns to Step J1.
In step J4, the image data is passed to the image display unit 2e to display a cross-sectional image. Then, the process returns to Step J1.
As described above, as shown in FIG. 26, image data G1,..., G6 at the respective cross-sectional positions S1,.

FIG. 27 is a flowchart showing the processing of the volume data generation unit 2g.
In step L1, the image data G1 to G6 at all the cross-sectional positions S1 to S6 are read from the mass storage device 3.
In step L2, as shown in FIG. 28, the volume data VD is calculated by interpolating between the cross-sectional positions S1 to S6 using the image data G1 to G6.

FIG. 29 is a flowchart of the process of the projection data generation unit 2h.
In step F1, the operator sets the projection direction.
In step F2, as shown in FIG. 30, the projection value of the pixel is obtained on the projection plane W from the value of the volume data on the projection line P that passes through the volume data VD and reaches the pixel on the projection plane W. To generate projection data PD. Then, the projection data is stored in the mass storage device 3. Here, the projection value includes a 3D value and a ZP value. The 3D value is a value obtained by various 3D display methods based on the most troublesome (or farthest) value exceeding the predetermined threshold value among the values of the volume data on the projection line P. . The ZP value is at least one of a maximum value, a minimum value, an average value, and (maximum value + minimum value) among the values of the volume data on the projection line P.
In step F3, the projection data PD is passed to the image display unit 2e to display the projection image.

FIG. 31 is a time chart of each process of the data acquisition unit 2a, the image data generation unit 2b, the volume data generation unit 2g, and the projection data generation unit 2h.
Time t0 is a scan start time. Time tj is the time at which the projection data PD is obtained.

The conventional X-ray CT apparatus 500 has a problem that it takes a long time from the scan start time t0 to the time tj at which the projection data PD is obtained.
Therefore, an object of the present invention is to provide a projection data generation method and an X-ray CT apparatus that can generate projection data at high speed.

In a first aspect, the present invention relates to an X-ray tube and a detector that move relative to a subject along one axis, stop at each of a plurality of cross-sectional positions on the axis, and at least X around the axis. In the X-ray CT apparatus provided with data acquisition means for acquiring data of all views necessary for generating image data by rotating the tube, generating the image data from the data acquired at each cross-sectional position is on the axis. Image data generating means for executing in the order of the cross-sectional positions arranged in line, and every time image data of a certain cross-sectional position is generated, a new one is created by interpolating between the cross-sectional position and the cross-sectional position where the image data was previously generated. Volume data sequential generation means for calculating and generating volume data, and each time a new volume data is generated, the volume data passing through the volume data and on each projection line reaching each pixel on the projection plane Projection data sequential generation means for generating new projection data by executing the maximum value, the minimum value, or the average value as the projection value of the pixel from the value of the image data for all the pixels on the projection plane. An X-ray CT apparatus is provided.
Conventionally, volume data is generated after all image data is generated, and then projection data is generated based on the volume data. On the other hand, in the projection data generation method according to the first aspect, partial volume data is sequentially generated every time image data of a plurality of cross-sectional positions is generated, and the partial volume data is Based on this, projection data is generated sequentially. As a result, the generation of projection data can proceed in parallel with the generation of the third and subsequent image data of the plurality of image data. Therefore, the time from the scan start time to the time when projection data is obtained can be shortened, and projection data can be generated at high speed. Further, since intermediate projection data can be obtained, an intermediate projection image can be displayed.

In a second aspect, the present invention generates image data by rotating at least the X-ray tube around the axis while relatively moving the X-ray tube and the detector along one axis with respect to the subject. In an X-ray CT apparatus provided with data acquisition means for acquiring necessary view data one after another, all the views required to generate image data at the cross-sectional position from data acquired before and after a certain cross-sectional position Image data generating means for calculating data and generating image data from the data in the order in which the plurality of cross-sectional positions on the axis are arranged on the axis; and each time image data at a certain cross-sectional position is generated Volume data sequential generation means for calculating and generating new volume data by interpolating between the cross-sectional position and the cross-sectional position where the image data was previously generated, and new volume data Each time it is generated, the maximum value, the minimum value, or the average value is obtained as the projection value of the pixel from the value of the volume data that passes through the volume data and reaches each pixel on the projection plane. There is provided an X-ray CT apparatus comprising projection data sequential generation means for generating new projection data by executing all pixels on a projection plane.
In the projection data generation method according to the second aspect, since the helical scan is performed, the scan time can be shortened. Then, the generation of projection data can proceed in parallel with the generation of image data in the same manner as the generation method of projection data according to the first aspect. Therefore, the time from the scan start time to the time when the projection data is obtained can be further shortened, and the projection data can be generated at a higher speed. Further, since intermediate projection data can be obtained, an intermediate projection image can be displayed.

  According to the X-ray CT apparatus of the present invention, partial volume data is sequentially generated every time image data of a plurality of cross-sectional positions is generated, and projection data is generated based on the partial volume data. Since the generation is performed sequentially, the generation of projection data can proceed in parallel with the generation after the third image data of the plurality of image data. Therefore, the time from the scan start time to the time when projection data is obtained can be shortened, and projection data can be generated at high speed. Further, since intermediate projection data can be obtained, an intermediate projection image can be displayed.

  Hereinafter, the present invention will be described in more detail with reference to embodiments of the present invention shown in the drawings. Note that the present invention is not limited thereby.

-First embodiment-
FIG. 1 is a configuration diagram of an X-ray CT apparatus according to a first embodiment of the present invention.
The X-ray CT apparatus 100 includes a scanner device 1, a processing device 2, a mass storage device 3 (for example, a hard disk device), a display monitor 4, and an input device 5.

  The scanner device 1 moves the X-ray tube and the detector relative to the subject along one axis (usually coincides with the body axis of the subject), stops at the cross-sectional position on the axis, Rotate the x-ray tube and detector around the axis to collect all the view data needed to generate the image data. In some cases, only the X-ray tube is rotated and the detector is not rotated.

  The processing device 2 includes a data acquisition unit 2a, an image data generation unit 2b, a volume data sequential generation unit 2c, a projection data sequential generation unit 2d, and an image display unit 2e.

FIG. 2 is a flowchart of the processing of the data acquisition unit 2a.
In step V1, as shown in FIG. 24, the operator sets a plurality of cross-sectional positions S1 to S6 on the Z axis (the X-ray tube and the detector are moved relative to the object to be fastened along this axis). Set.
In Step V2, the X-ray tube and the detector are moved relative to the subject along the Z axis, and Step V3 is repeated for each of the cross-sectional positions S1,. Note that relative movement means both when the subject is stationary and the X-ray tube and the detector are moved along the Z axis, and when both the X-ray tube and the detector are stationary and the subject is moved along the Z axis. It means to include.
In Step V3, the view is changed by rotating the X-ray tube and the detector around the Z axis (around the subject), and Step V4 is repeated for each view.
In step V4, data is acquired from the detector.
As described above, a data set at each of the cross-sectional positions S1, ..., S6 is obtained.

FIG. 3 is a flowchart of the processing of the image data generation unit 2b.
In step J1, steps J2 to J4 are repeated for each data set at the cross-sectional positions S1,..., S6.
In step J2, image reconstruction calculation (back projection calculation) is performed on the data set to obtain image data. Then, the image data is stored in the mass storage device 3 and transferred to the volume data sequential generation unit 2c.
In step J3, it is determined whether the operator has instructed to display a cross-sectional image. If the operator has instructed, the process proceeds to Step J4. If the operator has not instructed, the process returns to Step J1.
In step J4, the image data is passed to the image display unit 2e to display a cross-sectional image. Then, the process returns to Step J1.
As described above, as shown in FIG. 26, image data G1,..., G6 at the respective cross-sectional positions S1,.

FIG. 4 is a flowchart showing the processing of the volume data sequential generation unit 2c.
In step A1, step A2 is executed each time image data is delivered from the image data generation unit 2b.
In step A2, if the image data delivered from the image data generation unit 2b is the first image data, the process returns to step A1, and if the image data is the second image data or later, the process proceeds to step A3.
In step A3, as shown in FIG. 5A, when the second image data G2 is transferred, the first image data G1 and the second image data G2 are used to move between the cross-sectional positions S1 and S2. The partial volume data VD1 is calculated by interpolation, and is passed to the projection data sequential generation unit 2d. Further, as shown in FIG. 5B, when the third image data G3 is transferred, interpolation is performed between the sectional positions S2 to S3 by the partial volume data VD1 and the third image data G3. The partial volume data VD2 is calculated by combining with the partial volume data VD1, and is transferred to the projection data sequential generation unit 2d. The same applies to the fourth image data G4 and thereafter.

FIG. 6 is a flowchart of the process of the projection data sequential generation unit 2d.
In step B1, the operator sets the projection direction.
In step B2, step B3 is executed each time volume data is delivered from the volume data sequential generation unit 2c.
In step B3, if the volume data delivered from the volume data sequential generation unit 2c is the first partial volume data, the process proceeds to step B4, and if not, the process proceeds to step B5.
In step B4, as shown in FIG. 7A, the value of the volume data VD1 that exists on the projection line P that passes through the first partial volume data VD1 and reaches the pixel on the projection plane W is calculated. The projection value is obtained for all the pixels on the projection plane W to generate projection data PD1. Then, the projection data PD1 is stored in the mass storage device 3.
In step B5, as shown in FIG. 7B, when the second partial volume data VD2 is passed, the second partial volume data VD2 is passed through and the pixels on the projection plane W are passed. The projection value of the pixel is obtained from the value of the volume data VD2 existing on the projection line P leading to, and the projection data PD2 is generated. Then, the projection data PD2 is stored in the mass storage device 3. Note that the range included in the volume data VD1 in the volume data VD2 may be represented by the projection data PD1, so that it is not necessary to check the value. The same applies to the third and subsequent partial volume data. As shown in FIG. 7C, final projection data PD is generated in step B5 when final volume data VD is delivered.
In step B6, the projection data PD1,..., PD are passed to the image display unit 2e, and an intermediate projection image and a final projection image are displayed on the display monitor 4.

FIG. 8 is a time chart of each process of the data acquisition unit 2a, the image data generation unit 2b, the volume data sequential generation unit 2c, and the projection data sequential generation unit 2d.
Since the generation of the projection data PD1 to PD is advanced in parallel with the generation after the third image data G3, the time from the scan start time t0 to the time tn when the projection data PD is obtained can be shortened, and the projection data PD It becomes possible to generate at high speed. Further, since intermediate projection data PD1 to PD4 are obtained, it is possible to display an intermediate projection image.

FIG. 9 shows a screen layout example of the display monitor 4.
FIG. 9A shows a screen layout when a cross-sectional image, a 3D image, an MZP (Maximum IP) image, and an MPR (Multi Plane Recon) image are displayed simultaneously. The MPR image is a cross-sectional image when the volume data VD is cut along an arbitrary plane.
FIG. 9B shows a screen layout when a plurality of 3D images having different projection directions are displayed simultaneously.

-Second Embodiment-
FIG. 10 is a configuration diagram of an X-ray CT apparatus according to the second embodiment of the present invention.
The X-ray CT apparatus 200 includes a scanner device 1, a processing device 20, a mass storage device 3 (for example, a hard disk device), a display monitor 4, and an input device 5.

  The scanner device 1 is necessary for generating image data by rotating the X-ray tube and the detector around the axis while relatively moving the X-ray tube and the detector along one axis with respect to the subject. It is possible to perform a helical scan that collects data of each view one after another. In some cases, only the X-ray tube is rotated and the detector is not rotated.

  The processing device 20 includes a data acquisition unit 2a, an overlap image data generation unit 2f, a volume data sequential generation unit 2c, a projection data sequential generation unit 2d, and an image display unit 2e.

FIG. 11 is a flowchart of the processing of the data acquisition unit 2a.
In step H1, the imaging range and pitch (movement on the Z axis corresponding to one rotation of the X-ray tube) on the Z axis (moving the X-ray tube and the detector relative to the subject along this axis). The distance is set by the operator.
In step H2, data of each view necessary for generating image data is acquired one after another by helical scanning.

FIG. 12 is a flowchart of the process of the overlap image data generation unit 2f.
In step R1, steps R2 to R7 are executed every time necessary data is transferred from the data acquisition unit 2a. Here, the necessary data refers to data necessary for calculating a data set for generating first image data by image reconstruction calculation by interpolation calculation (for example, on the Z-axis corresponding to the first image data). The data necessary for sequentially generating the second and subsequent image data by weighting addition / subtraction to the previously generated image data.
In step R2, it is determined whether the image data to be generated is first image data. If it is the first image data, steps R3 and R4 are executed. If it is after the second image data, step R5 is executed.
In step R3, for example, a data set at the first cross-sectional position is calculated by interpolation calculation from data for 180 ° rotation before and after the first cross-sectional position corresponding to the first image data.
In step R4, an image reconstruction operation is performed on the data set to obtain first image data. Then, the first image data is stored in the mass storage device 3 and transferred to the volume data sequential generation unit 2c.

In step R5, a sequential generation calculation is performed to generate second and subsequent image data, which are stored in the mass storage device 3 and passed to the volume data sequential generation unit 2c.
Here, the sequential generation calculation will be described.
13 and 14 are explanatory diagrams of image data generation.
Each photographing position i is indicated by “01” to “12”.
The cross-sectional structure of the subject H at each imaging position i “01” to “12” is indicated by matrices H (01) to H (12).
The arrows around each of the matrices H (01) to H (12) indicate the view direction (scan direction).
The data at each shooting position i is represented by matrices C (01) to C (12) in which the corresponding element in the view direction corresponds to the projection value and the other elements are “0”. For example, since the view corresponding to the matrix C (01) is in the direction from the upper left to the lower right, the projection value is 2 + 4 = 6. Therefore, the projection value “6” is the upper left element and the lower right element of the matrix C (01). Further, the lower left element and the upper right element are “0”.

  The interpolation calculation uses the inverse proportionality of the distance, that is, the data C of the photographing position i is multiplied by the interpolation weight W that becomes smaller as the distance between the cross-sectional position and the photographing position i becomes larger, and the view data A of the sectional position is obtained. Can be thought of as doing. Therefore, assuming that the photographing position i “06” is a cross-sectional position and the interpolation weight W is 1/6 for each unit distance, the view data A at the cross-sectional position “06” is as shown in matrices A01 to A11. For example, the matrix A01 is obtained by multiplying the matrix C (01) by the interpolation weight 1/6.

Here, as shown in FIG. 14, six views A′01 to A′06 are created from the 11 views A01 to A11 using the opposite view. For example,
A'01 = A01 + A07
= C (01) × (1/6) + C (07) × (5/6)
It is.

Since the image reconstruction calculation can be considered as the sum of the matrixes A01 to A11 of each view data or the sum of A′01 to A′06, the matrix D (06) of the image data at the cross-sectional position “06” is
D (06) = A01 + ... + A11
= A'01 + ... + A'06
It becomes.
For the matrix D (06) of image data,
I (06) = D (06) / 2-27
To obtain a cross-sectional image I (06), the value of the upper left element of the cross-sectional image I (06) is “12”, the value of the lower left element is “15”, and the value of the upper right element is “13”. ", The value of the lower right element is" 14 ". If this cross-sectional image I (06) is compared with the matrix H (06) of the cross-sectional structure of the specimen H, this cross-sectional image I (06) shows a cross-section at the position “06” of the subject H. I understand.

  In general, when the view number n = 2m−1 (m is a natural number) required for the image reconstruction calculation, the view data at the cross-sectional position, the data for the (m−1) view on the front side of the cross-sectional position, and the back The (m-1) view data on the side may be used.

FIG. 15 and FIG. 16 are other explanatory views of image data generation.
This is obtained by changing the cross-sectional position = “06” in FIGS. 13 and 14 to the cross-sectional position = “07”.
Comparing FIGS. 13 and 14 with FIGS. 15 and 16, in FIGS. 13 and 14, the data C (01) to C (11) are used to generate the image data D (06). In FIG. 16, data C (02) to C (12) are used to generate image data D (07). That is, the data C (02) to C (11) are used redundantly. Such generation of different image data by overlapping use of data obtained by helical scanning is called “overlap image data generation”.

13 to 16, the interpolation method from the data corresponding to the 180 ° rotation before and after the cross-sectional positions “06” and “07” has been described. However, the data set corresponding to the 360 ° rotation before and after the cross-sectional position is sandwiched. The interpolation method from is the same.
17 to 20 show an interpolation method from a data set corresponding to 360 ° rotation before and after sandwiching the cross-sectional position “12”.
17 to 20, the view number n = 23 (in FIG. 13 to FIG. 16, n = 11). Further, the interpolation weight difference Q between the positions separated by the unit distance is 1/12 (Q = 1/6 in FIGS. 13 to 16).

As described with reference to FIGS. 13 and 14, the matrix D (06) of the image data at the cross-sectional position “06” is
D (06) = A01 + ... + A11
= A'01 + ... + A'06
It is. A01 to A11 are interpolation weights W = 1/6, 2/6, 3/6, 4/6, 5/6, 6/6, 5/6, 4 to C (01) to C (11). / 6, 3/6, 2/6, 1/6. Therefore, it can be written as:

Further, as described with reference to FIGS. 15 and 16, the matrix D (07) of the cross-sectional image at the cross-sectional position “07” is
D (07) = A01 + ... + A11
It is. A01 to A11 are obtained by multiplying C (02) to C (12) by the interpolation weight W. Therefore, it can be written as:

  If the equation (2) is subtracted from the equation (1), the following equation is obtained.

（数３）式を変形すれば、次式のようになる。

If the equation (3) is modified, the following equation is obtained.

（数４）式と同様に、次式が成立する。

Similar to equation (4), the following equation holds.

  The following general expression can be derived from (Expression 4) and (Expression 5).

(Equation 6) is expressed as follows: view number n = 2m−1 (m is a natural number) required for image reconstruction calculation, view position data and data for (m−1) view on the front side of the position. And a general formula in the case of generating a cross-sectional image using data of (m−1) views on the rear side.
The matrix D (06) in FIGS. 13 and 14 is a cross-sectional image at the first cross-sectional position (X = 1), and the matrix D (07) in FIGS. 15 and 16 is the second cross-sectional position (X = 2). 13 to 16 correspond to the case where n = 11 (m = 6) and K = 6 in the equation (6).
Equations (1) to (6) are derived assuming that data corresponding to 180 ° rotation before and after sandwiching the cross-sectional position as shown in FIGS. 13 to 16 is used. The equation can also be applied to the case where data corresponding to 360 ° rotation before and after sandwiching the cross-sectional position as shown in FIGS. 17 to 20 is used. That is, FIGS. 17 to 20 correspond to the case where n = 23 (m = 12) and K = 12 in the equation (6).

The operation of ΔCx in the equation (6) is very important for the calculation speed.
That is, in the case of ΔCx, C (X + K−2 + m) and C (X + K−2) do not calculate plus back projection and minus back projection, respectively, and first, data (projection value) C (X + K−2 + m) Taking the difference of C (X + K−2), the back projection is calculated for the obtained ΔCx. For example, in FIG. 13, when the third cross-sectional position (X = 3) is “08”, ΔC3-6 calculates the difference between C (07) and C (01) = 24, and then performs backprojection. Perform the calculation. ΔC3 calculates the difference between C (13) and C (07), and then calculates the back projection.
The difference between the positions of the first and second terms of ΔCx is m. Therefore, when using data corresponding to the 180 ° rotation before and after the cross-sectional position, the first term and the second term are in the relationship of the opposite view, and therefore ΔCx is the difference between the opposite view data (projection values). Makes sense. On the other hand, when a data set corresponding to 360 ° rotation before and after the cross-sectional position is used, since the first term and the second term are in an in-phase view relationship, ΔCx is the data (projection value) separated by 360 °. It makes sense to make a difference.

  As described above, the image data at the first cross-sectional position needs to be generated by the interpolation calculation and the image reconstruction calculation corresponding to the equation (1), but the cross-sectional image at the Xth (≧ 2) cross-sectional position is , (Equation 6). That is, the cross-sectional image at the Xth (≧ 2) cross-sectional position does not need to be subjected to interpolation calculation and image reconstruction calculation again for all views. It can be generated by simple addition and subtraction as shown in Equation 6 and image reconstruction calculation for only one view (ΔCx) for Ex−m and Ex (provided that Ex−m has already been calculated). You do not need to calculate again).

Returning to FIG. 12, in step R6, it is determined whether or not the operator has instructed to display a cross-sectional image. If the operator instructs, the process proceeds to step R7. If the operator has not instructed, the process returns to step R1.
In step R7, the image data is transferred to the image display unit 2e to display a cross-sectional image. Then, the process returns to Step R1.

  Returning to FIG. 10, the processing of the volume data sequential generation unit 2c is as described above with reference to FIG. Further, the process of the projection data sequential generation unit 2d is as described above with reference to FIG.

FIG. 21 is a time chart of each process of the data acquisition unit 2a, the overlap image data generation unit 2f, the volume data sequential generation unit 2c, and the projection data sequential generation unit 2d.
Since the helical scan is performed, the scan time can be shortened. Further, the image data can be generated in a short time by the overlap image data generation process. In addition, since the generation of the projection data PD1 to PD proceeds in parallel with the generation of the third image data G3 and subsequent generations, the time from the scan start time t0 to the time th at which the projection data PD can be obtained can be shortened. PD can be generated at high speed (substantially in real time). Further, since intermediate projection data PD1 to PD4 are obtained, an intermediate projection image can be displayed.

1 is a configuration diagram of an X-ray CT apparatus according to a first embodiment of the present invention. It is a flowchart of the data acquisition process in the X-ray CT apparatus of FIG. It is a flowchart of the image data generation process in the X-ray CT apparatus of FIG. 2 is a flowchart of volume data sequential generation processing in the X-ray CT apparatus of FIG. 1. It is explanatory drawing of partial volume data. It is a flowchart of the projection data sequential generation process in the X-ray CT apparatus of FIG. It is explanatory drawing of the production | generation process of projection data sequentially. It is a time chart of operation | movement of the X-ray CT apparatus of FIG. It is an illustration figure of the screen layout of the display monitor of the X-ray CT apparatus of FIG. It is a block diagram of the X-ray CT apparatus of the 2nd Embodiment of this invention. It is a flowchart of the data acquisition process in the X-ray CT apparatus of FIG. It is a flowchart of the overlap image data generation process in the X-ray CT apparatus of FIG. It is explanatory drawing of the production | generation of the image data by the data for 180 degrees before and behind. It is another explanatory drawing of the production | generation of the image data by the data for 180 degrees before and behind. It is another explanatory drawing of the production | generation of the image data by the data for 180 degrees before and behind. It is another explanatory drawing of the production | generation of the image data by the data for 180 degrees before and behind. It is explanatory drawing of the production | generation of the image data by the data for 360 degrees back and front. It is another explanatory drawing of the production | generation of the image data by the data for 360 degrees back and front. It is another explanatory drawing of the production | generation of the image data by the data for 360 degrees back and front. It is another explanatory drawing of the production | generation of the image data by the data for 360 degrees back and front. It is a time chart of operation | movement of the X-ray CT apparatus of FIG. It is a block diagram of an example of the conventional X-ray CT apparatus. It is a flowchart of the data acquisition process in the X-ray CT apparatus of FIG. It is explanatory drawing of several imaging position. It is a flowchart of the image data generation process in the X-ray CT apparatus of FIG. It is explanatory drawing of several image data. It is a flowchart of the volume data generation process in the X-ray CT apparatus of FIG. It is explanatory drawing of volume data. It is a flowchart which shows the projection data generation process in the X-ray CT apparatus of FIG. It is explanatory drawing of the production | generation process of projection data. It is a time chart of operation | movement of the X-ray CT apparatus of FIG.

Explanation of symbols

100, 200 X-ray CT apparatus 1 Scanner apparatus 2, 20 Processing apparatus 2a Data acquisition unit 2b Image data generation unit 2c Volume data sequential generation unit 2d Projection data sequential generation unit 2e Image display unit 2f Overlap image data generation unit 3 Large capacity Storage device 4 Display monitor 5 Input device

Claims (5)

Image data is generated by moving the X-ray tube and the detector relative to the subject along one axis, stopping at each of a plurality of cross-sectional positions on the axis, and rotating at least the X-ray tube around the axis. In an X-ray CT apparatus provided with data acquisition means for acquiring data of all views necessary for
Image data generating means for executing the generation of image data from the data acquired at each cross-sectional position in the order of the cross-sectional positions aligned on the axis;
Volume data sequential generation means for generating and generating new volume data by interpolating between the cross-sectional position and the cross-sectional position where the image data was previously generated every time image data of a certain cross-sectional position is generated,
Each time new volume data is generated, the maximum, minimum, or average value is projected from the value of the volume data on each projection line that passes through the volume data and reaches each pixel on the projection plane. An X-ray CT apparatus comprising projection data sequential generation means for generating new projection data by executing calculation as a value for all pixels on the projection plane. While moving the X-ray tube and detector relative to the subject along one axis, rotate at least the X-ray tube around the axis and acquire each view data necessary for generating image data one after another. In an X-ray CT apparatus provided with data acquisition means for
The calculation of the data of all views necessary to generate the image data at the cross-sectional position from the data acquired before and after a certain cross-sectional position, and generating the image data from the data for a plurality of cross-sectional positions on the axis Image data generating means for executing in the order in which they are arranged on the axis;
Volume data sequential generation means for generating and generating new volume data by interpolating between the cross-sectional position and the cross-sectional position where the image data was previously generated every time image data of a certain cross-sectional position is generated,
Each time new volume data is generated, the maximum, minimum, or average value is projected from the value of the volume data on each projection line that passes through the volume data and reaches each pixel on the projection plane. An X-ray CT apparatus comprising projection data sequential generation means for generating new projection data by executing calculation as a value for all pixels on the projection plane.   The X-ray CT apparatus according to claim 1, wherein the image generated by the image data generation unit is displayed according to an instruction from an operator.   4. The X-ray CT apparatus according to claim 1, wherein a projection image based on the projection data generated each time the new volume data is generated by the projection data sequential generation unit is displayed. 5. X-ray CT apparatus characterized by this. 5. The X-ray CT apparatus according to claim 1, wherein the MIP is based on a cross-sectional image represented by the image data generated by the image data generation unit and the projection data generated by the projection data sequential generation unit. Image (Maximum
An X-ray CT apparatus characterized by simultaneously displaying an IP image), a 3D image, and an MPR image (Multi Plane Recon image).

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