JP2001212128A - X-ray ct device and its photographing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain projection data of various detection widths by one photographing in the body axial direction of a subject, regarding an X-ray CT device and its photographing method. SOLUTION: For this X-ray CT device reconstitutes the CT tomographic image of a subject based on the detecting signal of a multi-row detector array 70, an X-ray source 40 which generated fan beams and the multi-row detector array 70 are confronted across the subject. In this case, for the multi-row detector array 70, a large number of X-ray detectors are arranged into an arc shape or a circumferential shape in the channel(CH) direction, and the large number of X-ray detectors are arranged in parallel in a plurality of rows in the body axis (Z axis) of the subject. In such an X-ray CT device, a collimator means 50 is inserted between an X-ray source 40 and the multi-row detector array 70. The collimator means 50 can asymmetrically change an X-ray beam width (w) in the body axial direction of the subject, cast on the multi-row detector array 70, into both sides of the center (CL-CL') in the body axial direction of the multi-row detector array.

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 an imaging method thereof, and more particularly, to an X-ray source for generating a fan beam and a large number of X-ray detectors arranged in an arc shape or a circumferential shape in a channel direction. A multi-row detector array, which is arranged and arranged in a plurality of rows in the body axis direction of the subject, faces each other across the subject, and the CT of the subject is detected based on a detection signal of the multi-row detector array. The present invention relates to an X-ray CT apparatus for reconstructing a tomographic image and an imaging method thereof.

[0002] In this type of X-ray CT apparatus, projection data for a plurality of rows is obtained from a multi-row detector array for each view, so that the imaging speed is increased.

[0003]

2. Description of the Related Art FIG. 8 is a configuration diagram of a main part of a conventional X-ray CT apparatus, mainly showing the configuration of an X-ray imaging unit and a data acquisition / processing unit. In the figure, reference numeral 30 denotes a scanning gantry for performing Axial / Herical scanning / reading of a subject by using an X-ray fan beam or the like, 40 denotes an X-ray tube, 150 denotes a collimator for limiting the irradiation width of the X-ray in the Z (body) axis direction, Reference numeral 51 denotes a collimator control unit, and reference numeral 70 denotes a multi-row detector array in which a number of X-ray detectors are arranged in an arc shape in the channel direction and are arranged in a plurality of rows in the body axis (Z-axis) direction of the subject. XDA), 80 is a data acquisition unit (DAS) provided with a data acquisition unit for a total of four systems for detection signals of each column of the multi-row detector array 70, and 15 accumulates projection data acquired by the data acquisition unit 80. Data acquisition buffer 11, main control and processing of X-ray CT apparatus (imaging control, CT image reconstruction processing, etc.)
A display unit (CRT) 13 for displaying an X-ray CT image or the like; and a control interface 14 of the central processing unit 11. Although not shown, a collimator for limiting the irradiation width of the X-ray in the fan direction is separately provided.

FIG. 1A shows a plan view of a conventional collimator 150. In this collimator 150, a direction perpendicular to the Z axis (corresponding to the body axis of the subject) (direction indicated by arrow X in the figure)
The two parallel slit plates 150a and 150b provided in
The links 152a, 152b are rotatably stopped by pins 154 at four corners so as to form a parallelogram with the links 152a, 152b, and the links 152a, 152b are supported on the support shafts 15 on their center lines CL.
3a and 153b, each of which is rotatably supported,
The shaft 153b of the link 152b is connected to the geared motor 155.
, The slit width w in the Z-axis direction can be symmetrically and continuously changed before and after the center line CL as a boundary.

The multi-row detector array 70 includes, for example, eight rows of sub-arrays SA1 to SA8. Each of the sub-arrays SA1 to SA8 has a large number (for example, about n = 1000) of X-ray detectors in an arc shape. Are arranged in a row.
The multi-row detector array 70 is arranged such that the projection CL ′ of the center line CL of the collimator 150 exactly corresponds to the position on the boundary between the sub-arrays SA4 and SA5. Therefore, by changing the slit width w of the collimator 150, the X-ray beam width in the Z-axis direction applied to the multi-row detector array 70 can be changed symmetrically before and after the boundary between the sub-arrays SA4 and SA5. Becomes

[0006] When imaging the subject, the central processing unit 1
1 outputs an instruction C1 of a slit width w corresponding to a detection width of the subject in the body axis direction to the collimator control unit 51 via the control interface 14 in accordance with an instruction of a scan protocol (imaging plan) from the operator in advance. . The collimator control unit 51 controls the geared motor 155 according to the instruction C1, and sets the collimator 150 to the specified slit width w. Further, the central processing unit 11 outputs an imaging pattern instruction C2 to the data collection unit 80 in accordance with the imaging plan instruction. Here, the imaging pattern represents an imaging pattern indicating what detection width (slice thickness) is to be taken in the body axis direction of the subject. The data collection unit 80 receives the instruction C2
, The detection signals of the sub-arrays SA1 to SA8 are connected to the data collection units for four series.

Next, the configuration of the data collection unit 80 and the mode of signal connection in the data collection unit 80 according to the above-described imaging pattern will be described in detail. FIG. 9 is a diagram showing the configuration of a conventional data collection / arithmetic system. In the figure, reference numeral 70 denotes a multi-row detector array (XDA), and XDA1 to XDA8 (corresponding to the sub-arrays SA1 to SA8 in FIG. 8). Eight columns of sub-arrays constituting the array 70, XD1 to XDn are, for example, an X-ray detector including a scintillator and a photodiode,
Reference numeral 81 denotes an analog switch unit (ASW) that performs signal connection switching between a detection signal of each column of the sub-arrays XDA1 to XDA8 and a data collection unit for four systems to be described later, reference numeral 80 denotes a data collection unit (DAS), and DAS1 to DAS4. Is a data collection unit for four series constituting the data collection unit 80,
G1 to IGn are integrators (such as Miller integrators), A1 to An
Is an amplifier, SH1 to SHn are sample and hold circuits, S
MPX is a signal multiplexer for analog signals, A / D is a high-speed A / D converter, 82 is a data multiplexer (DMPX) for digital signals, 15 is a data acquisition buffer for main signal data (projection data), and 11 is a central processing unit. ,
11a is the CPU, 11b is a main memory (MEM) storing a control program and the like executed by the CPU 11a,
Reference numeral 14 denotes a control interface of the CPU 11a.

[0008] Returning to Fig. 8, the outline of the photographing operation will be described.
The fan beam from the X-ray tube 40 is
And simultaneously enter the multi-row detector array 70. FIG.
Now, the X-ray beam XB11 (subarray XDA
1, corresponding to the detection channel CH1), the X-ray detector XD1 outputs a current signal corresponding to the transmission intensity of the X-ray beam XB11, and the integrator IG1 outputs the detection output current of the X-ray detector XD1. Is integrated by a predetermined time constant to output a corresponding X-ray beam amount detection voltage. Further, the amplifier A1 amplifies the output voltage of the integrator IG1, and the sample and hold circuit SH1 samples and holds the output voltage of the amplifier A1 at a predetermined timing. The above is another X-ray beam X
The same applies to the signal processing of B12 to XB1n.

Further, the signal multiplexer SMPX multiplexes the output signals of the sample hold circuits SH1 to SHn at high speed, and the A / D converter A / D converts the output signal of the signal multiplexer SMPX at high speed. The same applies to the signal processing of the other DAS2 to DAS4.

Further, each output data of DAS1 to DAS4 is multiplexed by a data multiplexer DMPX, and a series of obtained main signal data (projection data) is stored in a data collection buffer 15. And the CPU 11
a (processing for reconstructing an X-ray CT image, etc.).

Next, the relationship between the analog switch section 81 and the imaging pattern will be described. As an imaging pattern in a conventional X-ray CT apparatus, as shown in FIG.
A first imaging pattern which simultaneously captures a plurality of columns of image data 00 in a body axis direction with a relatively wide detection width W2 per view;
As shown in FIG. 10B, there are two patterns of a subject 100, and a second imaging pattern for simultaneously imaging a plurality of rows in a narrow (precise) detection width W1 in the body axis direction per view.

Returning to FIG. 9, the analog switch section 81 has a sub-array XDA corresponding to the first and second imaging patterns.
1 to XDA8 are connected to the corresponding data acquisition units DAS1 to DAS4. That is, for example, now D
Focusing on the integrator IG1 of the AS1, three detection current signals A11, A21, and A31 from the sub-arrays XDA1 to XDA3 can be input to the input through three switches. Here, the first number of the subscript "1,
"2, 3" represents the column number of the sub-array, and the second numeral "1" represents a signal of the detection channel CH1. The first imaging pattern includes signals A11 and A2 as shown in the figure.
1 are connected to the integrator IG1. These signals A11 and A21 are added at the input of the integrator IG1. As a result, the sub-arrays XDA1 and XDA2 in this case are substantially one column having a width of two columns. It will function as a sub-array of minutes.

In the second imaging pattern, only the signal A31 is connected to the integrator IG1, and the sub-array XDA3 in this case functions as a sub-array for one column having an original one column width. The same applies to the signal connection to DAS2 to DAS4.

As shown by an arrow a in FIG.
Some devices include preamplifiers PA1 to PAn before the integrators IG1 to IGn and convert (including logarithmic conversion) an input current signal (current addition signal) to a corresponding voltage signal. The integrators IG1 to IGn in this case are:
An input voltage signal is integrated to generate a corresponding X-ray beam amount detection voltage, and this type of X-ray CT apparatus is also applicable to the present invention.

Next, a practical image taken according to the above-mentioned image pickup pattern will be described. FIG. 10 is a view for explaining an imaging method of a conventional X-ray CT apparatus, and FIG. 10A shows an imaging image according to a first imaging pattern. In the figure, in the data collection system in this case, the sub-arrays XDA1 and XDA
2 (however, only A1 and A2 are shown in the figure due to space limitations; the same applies to the following).
n) is added for each channel, and the integrator I of DAS1 is added.
G1 to IGn. Similarly, the set of subarrays XDA3 and XDA4 is input to DAS2, the set of subarrays XDA5 and XDA6 is input to DAS3, and the set of subarrays XDA7 and XDA8 is input to DAS4.

Further, the slit width w of the collimator 150 is adjusted to a necessary minimum according to the first imaging pattern. The inset (a) shows a plan view of the collimator 150. In this case, the links 152a and 152b are located at the center line CL.
The parallel slit plates 150a and 150b are symmetrically symmetrical about the center line CL and are separated from each other to a position where the maximum separation width is obtained.
That is, the slit width w is maximum. Accordingly, the detection width of the subject 100 in the body axis direction is also maximum, and at this time, the multi-row detector array 70 (that is, the sub-array XDA1
To XDA8) is uniformly irradiated with an X-ray beam.

At the time of imaging, in the case of Axial scanning, the imaging table (ie, the subject 100) intermittently moves by the pitch P in the body axis direction for each rotation of the scanning gantry.
In the case of Hrical scanning, the imaging table continuously moves by the pitch P in the body axis direction with one rotation of the scanning gantry. In any case, projection data for a width of 2 × 4 columns can be acquired for each view, and the imaging efficiency is good. In addition, by appropriately selecting the pitch P, a desired imaging region of the subject 100 can be imaged without gaps. Therefore, such a first imaging pattern is suitable for roughly examining the presence or absence of a disease in a wide area (such as the chest) of the subject.

FIG. 10B shows a photographed image according to the second image pickup pattern. In the figure, in the data collection system in this case, the central sub-arrays XDA3 to XDA
The six detection channel signals (CH1 to CHn) are input to the integrators IG1 to IGn of DAS1 to DAS4 in a one-to-one correspondence, so that accurate projection data can be obtained for each DAS.

Further, the slit width w of the collimator 150 is adjusted to a necessary minimum according to the second imaging pattern. The inset (a) shows a plan view of the collimator 150. In this case, both the links 152a and 152b are urged to the side of the center line CL, so that the parallel slit plates 150a and 150b approach each other approximately １ ／ of the maximum width symmetrically with respect to the center line CL. are doing. At this time, the slit width w is about 1/2 of the maximum. As a result, the detection width of the subject 100 in the body axis direction is also about half of the maximum, and at this time, uniform X-rays are applied only to the central subarrays XDA3 to XDA6 in the multi-row detector array 70. The beam is illuminated.

In imaging, 4 per view
Accurate projection data for the column width can be obtained, and imaging efficiency is good. Further, by appropriately selecting the pitch P, the subject 10
It is possible to shoot a desired shooting area of 0 finely without gaps. Therefore, such a second imaging pattern is suitable for, for example, detailed imaging of an affected part of a subject. Thus, conventionally, an eight-row multi-row detector array 70 and four data acquisition units DAS1-
By combining GAS4, the speed of X-ray CT imaging has been increased.

[0021]

However, as described above, if the detection width of the subject 100 in the body axis direction can be changed only symmetrically around the center line CL, various imaging according to various medical purposes can be performed. I can't respond to requests efficiently. That is, for example, there may be a case in which, from the chest to the abdomen of the subject 100, it is desired to efficiently obtain projection data with no gap, which can roughly check for the presence or absence of a disease, and precise projection data at a required place.

However, according to the above-mentioned conventional method, in order to meet this demand, first, a radiographing without a gap from the chest to the abdomen of the subject 100 is performed in accordance with the first imaging pattern of FIG. It is necessary to perform precise imaging of the subject 100 at a required location in accordance with the second imaging pattern of FIG. 10 (B), and such twice imaging requires not only a long time but also a large amount of time. This has led to overexposure.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object the object of the present invention is to provide an X-ray projection system capable of efficiently obtaining projection data of various detection widths in one imaging in the body axis direction of a subject. An object of the present invention is to provide a line CT apparatus.

[0024]

The above-mentioned problem is solved, for example, by referring to FIG.
Is solved. That is, the X-ray C of the present invention (1)
The T apparatus has an X-ray source 40 for generating a fan beam, and a large number of X-ray detectors arranged in an arc shape or a circumferential shape in a channel (CH) direction and arranged in a plurality of rows in the body axis direction of the subject. In the X-ray CT apparatus, the provided multi-row detector array 70 faces each other across the subject, and reconstructs a CT tomographic image of the subject based on the detection signal of the multi-row detector array 70.
Interposed between the X-ray source 40 and the multi-row detector array 70, the X-ray beam width w in the body (Z) axis direction of the subject to be irradiated on the multi-row detector array 70 is changed. Is provided with collimator means 50 which can be changed asymmetrically on both sides of the center CL 'in the body axis direction.

According to the present invention (1), the collimator means 5
0 indicates that the X-ray beam width w in the body axis direction of the subject irradiated on the multi-row detector array 70 can be changed asymmetrically on both sides of the center CL ′ in the body axis direction of the multi-row detector array. Projection data with a relatively wide detection width and projection data with a narrow (precise) detection width can be acquired at a glance for each view of imaging, so that it is possible to efficiently meet requests for imaging according to various medical purposes.

The present invention (1) is also applicable to a two-row detector array having two X-ray detectors. That is,
Now, with reference to FIG. 1A, the detection columns A1 to A4 of the multi-row detector array 70 are a first sub-array of one column,
The detection rows A5 to A8 are the second sub-arrays for another row. According to the present invention (1), the entirety (corresponding to the areas A1 to A4) for the first sub-array of such a two-row detector array 70 and one for the second sub-array. Only the portion (corresponding to the area A5) can be irradiated with the X-ray beam. As a result, projection data having a substantially wide detection width can be efficiently obtained from the first sub-array, and projection data having a substantially narrow detection width can be simultaneously obtained from the second sub-array.

The above-mentioned problem can be solved, for example, by the structure shown in FIG. That is, in the X-ray CT apparatus of the present invention (2), an X-ray source 40 for generating a fan beam, and a large number of X-ray detectors are arranged in an arc shape or a circumferential shape in a channel (CH) direction, and are covered. A multi-row detector array 70 arranged in a plurality of rows in the body axis direction of the sample is opposed to each other across the subject, and a CT tomographic image of the subject is formed based on a detection signal of the multi-row detector array 70. In the X-ray CT apparatus to be reconstructed, each of a plurality of sets of detection signals A1 to A8 of each row of the multi-row detector array 70 is combined with a different number of sets (for example, each set of four rows and one row). Signal combining means 81 for combining signals (for example, signals A1 to A4 and a single signal A5) for each channel.
And a plurality of data collection units DAS1 and DAS2 for generating and collecting projection data of the subject corresponding to a plurality of sets based on the respective output signals of the signal synthesizing means 81, and based on the collected data of the respective data collection units DAS1 and DAS2. Data processing means 11 for reconstructing CT tomographic images having a plurality of detection widths corresponding to a plurality of sets.

According to the present invention (2), the signal synthesizing means 81 for synthesizing a plurality of sets of detection signals obtained by combining the detection signals of the respective columns of the multi-row detector array 70 in different numbers for each channel. With this configuration, with a simple configuration as a whole, projection data with a relatively wide detection width and projection data with a narrow (precise) detection width can be acquired at once for each view of imaging, thereby complying with various medical purposes. Efficiently respond to shooting requests.

The above problem can be solved, for example, by the structure shown in FIG. That is, in the X-ray CT apparatus of the present invention (3), an X-ray source 40 for generating a fan beam and a large number of X-ray detectors are arranged in an arc shape or a circumferential shape in a channel (CH) direction, and are covered. A multi-row detector array 70 arranged in a plurality of rows in the body axis direction of the sample is opposed to each other across the subject, and a CT tomographic image of the subject is formed based on a detection signal of the multi-row detector array 70. In the X-ray CT apparatus to be reconstructed, a plurality of data acquisition units DAS1 to DAS8 for generating and acquiring projection data of the subject based on the detection signals A1 to A8 of each column of the multi-row detector array 70, respectively, A plurality of sets of collected data (for example, signals A1 to A4 and a single signal A5) obtained by combining the collected data of the collecting units DAS1 to DAS8 with different numbers of sets (for example, four rows and one row). By combining for each channel Data processing means 11 for reconstructing a CT tomographic image of the plurality detection width corresponding to the set
Is provided.

According to the present invention (3), the data processing means 1
1 combines, by software means, the collected data of each data collection unit in a different number of sets, combines the obtained plurality of sets of collected data of each set for each channel, and detects a plurality of detected data corresponding to each of them. By reconstructing a CT tomogram having a wide width, it is possible to more flexibly respond to a demand for imaging according to various medical purposes.

Further, according to the imaging method of the present invention (4), the X-ray source 40 for generating a fan beam and a number of X-ray detectors are arranged in an arc shape or a circumferential shape in the channel (CH) direction. A multi-row detector array 70 arranged in a plurality of rows in the body axis direction of the subject faces each other across the subject, and a CT tomographic image of the subject is generated based on a detection signal of the multi-row detector array 70. In the imaging method of the X-ray CT apparatus for reconstructing the object, each projection data corresponding to a different detection width in the body axis direction of the subject is simultaneously detected and collected for each view for imaging the subject, and the projection data corresponding to each of the projection data is detected and collected. This is for reconstructing CT tomographic images having a plurality of detection widths.

[0032]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the same reference numerals indicate the same or corresponding parts throughout the drawings. FIG. 2 is a block diagram of the X-ray CT apparatus according to the embodiment. In the figure, reference numeral 10 denotes an operation console operated by a user, reference numeral 20 denotes an imaging table on which a subject is placed and moved in the body axis direction, and reference numeral 30 denotes an X-ray fan. A of the subject by beam
This is a scanning gantry that performs xial / Herical scanning and reading.

In the scanning gantry 30, reference numeral 40 denotes an X-ray tube; 41, an X-ray control unit for controlling the X-ray irradiation time and intensity (tube voltage kV, tube current mA); Collimator that limits the detection width of the specimen in the body axis direction)
Reference numeral 51 denotes a collimator control unit that controls the collimator 50;
0 denotes an imaging unit configuration (X-ray tube 40, multi-row detector array 70)
Etc.), a rotation control unit for rotating the subject around the body axis of the subject, 7
Reference numeral 0 denotes a multi-row detector array in which a large number of X-ray detectors are arranged in a plurality of rows of arcs, and reference numeral 80 denotes a data acquisition unit (DAS) that acquires detection data of the multi-row detector array.

In the operation console 10, reference numeral 11 denotes a central processing unit that performs main control and processing (scan control, CT image reconstruction processing, etc.) of the X-ray CT apparatus, 12 denotes an input device including a keyboard and a mouse, and 13 denotes a scan. A display device (CR) for setting a protocol (imaging parameters kV, mA, Sec, Thic, etc.) and displaying a CT reconstructed image
T) and 14 are control interfaces for outputting various control signals and the like to the scanning gantry 30 and the imaging table 20, 15 is a data acquisition buffer for accumulating main signal data from the data acquisition unit 80, and 16 is for operation of the X-ray CT apparatus. A secondary storage device (such as a disk) that stores various necessary data, application programs, and the like.

FIG. 3 is a configuration diagram of a main part of the X-ray CT apparatus according to the embodiment, and mainly shows a configuration of an X-ray imaging unit and a collection / processing unit of projection data. The basic configuration of FIG.
It may be the same as that described above. However, the collimator 50 according to the present embodiment is different in that the slit width w in the Z-axis direction can be changed independently and asymmetrically before and after the center line CL.

FIG. 3A is a plan view of an example of the collimator 50 according to the present embodiment. This collimator 50
On one side, a center line CL assumed in a direction perpendicular to the Z axis and a slit plate 50a provided in parallel with the center line CL form pins 54a, 54a, 52a, 52b so as to form a parallelogram with the two links 52a, 52b. 54b and a common support shaft 53a, 53b so as to be rotatable, and a link 5 therein.
The end of 2b is reciprocated by an eccentric cam 56a fixed to the rotation drive shaft of the geared motor 55a and a link mechanism 57a interlocking with the cam 56a, so that the slit plate 50a forms the center line CL in the Z axis. The direction slit width wa can be independently and arbitrarily changed.

On the other side of the collimator 50, the center line CL and a slit plate 50b provided in parallel with the center line CL are provided.
And the pins 54c and 54d and the common support shafts 53a and 53b so that they form a parallelogram with the two links 52c and 52d.
Is rotatably stopped by the link 52.
The end of d is driven to reciprocate by an eccentric cam 56b fixed to the rotation drive shaft of the geared motor 55b and a link mechanism 57b interlocked with the cam 56b, so that the slit plate 50b forms a center line CL with the Z axis. Slit width w
b can be arbitrarily changed independently.

The multi-row detector array 70 of one example is composed of eight rows of sub-arrays SA1 to SA8, and the projection CL 'of the center line CL onto the multi-row detector array 70 is just the sub-arrays SA4 and SA5. And a relationship corresponding to the position on the boundary line. Therefore, by changing the slit width w (wa and / or wb) of the collimator 50, the width formed by the center line CL and the slit plates 50a and / or 50b can be individually changed. The X-ray beam width in the body axis direction to be irradiated
4, asymmetrically before and after the boundary of SA5.

With this configuration, when imaging the subject, the central processing unit 11 follows the instruction of the scan protocol (imaging plan) from the operator in advance, and the slit width w corresponding to the detection width of the subject in the body axis direction. (Wa and / or wb)
Is output to the collimator control unit 51 via the control interface 14. The collimator control unit 51 controls the geared motors 55a and 55b according to the instruction C1, and sets the collimator 50 to a specified slit width w.

The central processing unit 11 has a first
The third / fourth imaging pattern instruction C2 in the present embodiment is output to the data collection unit 80 according to the present embodiment in accordance with the imaging plan instruction. The data collection unit 80 connects the detection signals of the sub-arrays SA1 to SA8 to the data collection units for two series according to the instruction C2.

FIG. 4 is a diagram showing the configuration of a data collection / arithmetic system according to the first embodiment.
A1 to SA8 (note that, in FIG.
SA8 is referred to as a sub-array XDA1 to XDA8 (hereinafter referred to as XDA1 to XDA8).
1) Data collection units DAS1 and D for two systems
The case where it relates to AS2 is shown.

Here, the imaging pattern according to the present embodiment will be described. For example, as shown in FIG.
0 is simultaneously imaged in the body axis direction with a relatively wide detection width W4 and a narrow (precision) detection width W1, and the subject 100 is moved in the body axis direction as shown in FIG. There are two patterns: a fourth detection pattern for photographing with a wide detection width W8 and a relatively narrow detection width W2. Although each of the detection widths W8 and W2 in FIG. 5B is symmetrically spread before and after the center line CL, in the present embodiment, each of the detection widths W8 and W2 to be detected by DAS1 and DAS2 is used.
It is asymmetric in the sense that W2 is different.

Returning to FIG. 4, the analog switch section 81 according to the first embodiment is provided with the detection signals of the sub-arrays XDA1 to XDA8 and the data collection units DAS1 and DAS2 for two series in accordance with the third and fourth imaging patterns. Switch the connection between and. That is, when attention is focused on, for example, the integrator IG1 of the DAS1, the input of the subarrays XDA1 to XDA1 through the eight (four in FIG.
Eight detection current signals A11 to A81 from DA8 can be input. The third imaging pattern connects the signals A11 to A41 together to the integrator IG1 of the DAS1 as shown in the figure, and these signals A11 to A41 are subjected to current addition at the input of the integrator IG1, resulting in a sub-array in this case. XDA1 to XDA4 function as a subarray for one column having a width of substantially four columns. Although not shown, the signal strings A51 to A51 of the sub-array XDA5 are simultaneously displayed.
5n are independently connected to the integrators IG1 to IGn of the DAS2.

The fourth imaging pattern includes signals A11 to A81.
Are both connected to the integrator IG1 of the DAS1.
These signals A11 to A81 are subjected to current addition at the input of the integrator IG1, and as a result, the subarrays XDA1 to XDA in this case are added.
DA8 will function as a subarray for one column having a width of substantially eight columns. At the same time, the signals A41 and A5
1 are connected to the integrator IG1 of the DAS2. These signals A41 and A51 are added to the current at the input of the integrator IG1.
4, XDA5 will function as a subarray of one column having a width of substantially two columns. In this case, DA
The detection targets of S1 and DAS2 are some of the sub-arrays XDA
4 and XDA5.

Alternatively, when the detection targets of DAS1 and DAS2 are not overlapped in the fourth imaging pattern,
Signals A11 to A31 and signals A61 to A81 are both DA
Connected to the integrator IG1 of S1 and the signals A41, A51
May be connected to the integrator IG1 of the DAS2.

FIG. 5 is a view for explaining an imaging method of the X-ray CT apparatus according to the first embodiment, and FIG. 5A shows an imaging image according to a third imaging pattern. In the figure, in the data collection system in this case, the sub-arrays XDA1 to XDA1
Each detection channel signal (CH1 to CHn) of XDA4 (however, simply shown as A1 to A4 in the drawing because of space) is added for each channel, and the integrators IG1 to IG of DAS1 are added.
n. At the same time, each of the detection channel signals (CH1 to CHn) of the sub-array XDA5 is individually set to DAS2.
To the integrators IG1 to IGn.

Further, the slit width w of the collimator 50 is adjusted to a necessary minimum according to the third imaging pattern. The inset (a) shows a plan view of the collimator 50.
In this case, the links 52a and 52b are linked to the link mechanism 57a.
The slit plate 50a is urged to an angle substantially perpendicular to the center line CL, thereby separating the slit plate 50a from the center line CL to a position having the maximum separation width. On the other hand, the links 52c and 52d are connected to the center line CL by the link mechanism 57b.
, Whereby the slit plate 50b is located very close to the center line CL. The detection width of the subject 100 in the body axis direction also corresponds to this. At this time, a uniform X-ray beam is emitted only to the sub-arrays XDA1 to XDA5.

In the case of Axial scanning, the imaging table 20 intermittently moves by the pitch P in the body axis direction for each rotation of the scanning gantry 30 in the case of Axial scanning, and one rotation of the scanning gantry 30 in the case of Hrical scanning. At the same time, the imaging table 20 moves continuously by the pitch P in the body axis direction. In any case, it is possible to simultaneously acquire four columns of projection data and one column of precise projection data for each view. Further, by appropriately selecting the pitch P, the subject 10
0 can be photographed without gaps. Therefore, it can be said that this third imaging pattern is extremely suitable for an imaging purpose such as a physical examination of the subject.

FIG. 5B shows a photographed image according to the fourth image pickup pattern. In the figure, in the data collection system in this case, the detection channel signals (CH1 to CHn) of the subarrays XDA1 to XDA8 are added for each channel and input to the integrators IG1 to IGn of the DAS1, and simultaneously, each of the subarrays XDA4 and XDA5. Detection channel signals (CH1 to CHn) are added for each channel, and DA
It is input to the integrators IG1 to IGn of S2.

Further, the slit width w of the collimator 50 is adjusted to a necessary minimum according to the fourth imaging pattern. The inset (a) shows a plan view of the collimator 50.
In this case, each pair of the links 52a, 52b and 52c, 52d is connected to a center line C by a link mechanism 57a, 57b.
The slit plates 50a and 50b are urged to an angle substantially perpendicular to L, thereby separating the slit plates 50a and 50b from the center line CL to a position where the maximum separation width is obtained. At this time, the total slit width w is the maximum, and the multi-row detector array 70
(Subarrays XDA1 to XDA8) are irradiated with a uniform X-ray beam. Therefore, at the time of imaging, it is possible to simultaneously obtain projection data for eight columns and relatively precise projection data for two columns for each view. By appropriately selecting the pitch P, a desired imaging region of the subject 100 can be imaged without gaps. Therefore, this fourth imaging pattern is also suitable for an imaging purpose such as a physical examination of the subject.

FIG. 6 is a diagram showing the configuration of a data collection / arithmetic system according to the second embodiment.
Each of the channel detection signals of DA1 to XDA8 (corresponding to the subarrays SA1 to SA8 in FIG. 3) is connected to the data collection units DAS1 to DAS8 for eight systems on a one-to-one basis, and any of the subarrays XDA1 to XDA8 is detected. This is a case in which the processing is performed exclusively by software processing of the CPU 11a. In addition, the analog switch 81 is omitted from the data collection unit 80, so that the CPU 11a does not output the instruction C2 of the imaging pattern to the data collection unit 80.

FIG. 7 is a view for explaining an imaging method of the X-ray CT apparatus according to the second embodiment, and FIG.
3A shows a captured image according to a third imaging pattern similar to that of FIG. In the figure, the control of the collimator 50 may be the same as in FIG. 5A. On the other hand, in the second embodiment, each detection data of the sub-arrays XDA1 to XDA5 is collected by the DAS1 to DAS5, respectively, and stored in the data collection buffer 15. Note that the subarrays XDA6 to XDA
No. 8 has no projection data in DAS6 to DAS8 (or 0), and is not a processing target. CPU
11A processes the projection data of DAS1 to DAS4 by adding (or averaging) each of them for each channel, and processing the projection data of DAS5 independently by using the processing shown in FIG. And a third imaging pattern similar to the above is realized.

FIG. 7B shows a photographed image according to the fifth image pickup pattern. In the figure, the collimator 50
May be the same as in FIG. 5B. On the other hand, in the second embodiment, all the detection data of the sub-arrays XDA1 to XDA8 are collected by the DAS1 to DAS8, respectively, and stored in the data collection buffer 15. The CPU 11a is a DAS
By adding (or averaging) the main signal data of 1 to DAS8 for each channel and processing them, and processing the main signal data of DAS4 or DAS5 independently, the fifth imaging pattern is obtained. Has been realized.
Alternatively, the CPU 11a may realize the fourth imaging pattern similar to that of FIG. 5B by adding (or averaging) each of the projection data of DAS4 and DAS5 for each channel and processing. In any case, according to the second embodiment, since the detection width of the subject 100 can be arbitrarily determined by the CPU 11a, it is possible to flexibly cope with various imaging requests.

In the above embodiments, some examples of the asymmetrical detection width of the subject have been described. However, various other asymmetrical forms are conceivable.

In the above embodiment, the collimator 50 is used.
Although the configuration of one example has been described, the collimator 50 can have various other configurations.

In the above embodiment, the detector array 70 having eight rows has been described, but it is apparent that the present invention is not limited to this.

In the above embodiment, an example of application to an X-ray CT apparatus using a fan beam system (a so-called RR system) has been described. Obviously, the present invention can be applied to an X-ray CT apparatus of a so-called SR type or the like arranged in a row.

Although a plurality of embodiments suitable for the present invention have been described, it is to be understood that various changes in the configuration, control, processing, and combinations thereof can be made without departing from the spirit of the present invention. Not even.

[0059]

As described above, according to the present invention, projection data of various detection widths can be efficiently obtained by one imaging in the body axis direction of a subject, and therefore, it is possible to flexibly meet various imaging requests for medical purposes. There is a great deal of potential to cope with it and contribute to speeding up and improving reliability of X-ray CT medical treatment.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram of the X-ray CT apparatus according to the embodiment.

FIG. 3 is a configuration diagram of a main part of the X-ray CT apparatus according to the embodiment.

FIG. 4 is a diagram illustrating a configuration of a data collection / arithmetic system according to the first embodiment.

FIG. 5 is a diagram illustrating an imaging method of the X-ray CT apparatus according to the first embodiment.

FIG. 6 is a diagram showing a configuration of a data collection / arithmetic system according to a second embodiment.

FIG. 7 is a diagram illustrating an imaging method of the X-ray CT apparatus according to the second embodiment.

FIG. 8 is a configuration diagram of a main part of a conventional X-ray CT apparatus.

FIG. 9 is a diagram showing a configuration of a conventional data collection / operation system.

FIG. 10 is a diagram illustrating an imaging method of a conventional X-ray CT apparatus.

[Explanation of symbols]

 Reference Signs List 10 operation console 11 central processing unit 12 input device 13 display device 14 control interface 15 data collection buffer 20 imaging table 30 scanning gantry. Reference Signs List 40 X-ray tube 50 Collimator 50a, 50b Slit plate 52a-52d Link 53a, 53b Support shaft 54a-54d Pin 55a, 53b Geared motor 56a, 56b Eccentric cam 57a, 57b Link mechanism unit 70 Multi-row detector array (XDA) 80 Data acquisition unit (DAS) 81 Analog switch unit (ASW) 82 Data multiplexer (DMPX) 150 Collimator A1 to An amplifier DAS1 to DAS4 Data acquisition unit IG1 to IGn Integrator SA1 to SA8 (XDA1 to XDA8) Subarray SH1 to SHn Sample hold Circuit SMPX signal multiplexer XD1-XDn X-ray detector

Claims (4)

[Claims] An X-ray source for generating a fan beam and a number of X-ray detectors are arranged in an arc shape or a circumferential shape in a channel direction and are arranged in a plurality of rows in a body axis direction of a subject. And a multi-row detector array facing each other across the subject, and reconstructing a CT tomographic image of the subject based on detection signals of the multi-row detector array. Interposed between the detector array and the X-ray beam width in the body axis direction of the subject irradiating the multi-row detector array can be asymmetrically changed on both sides of the center of the multi-row detector array in the body axis direction. An X-ray CT apparatus comprising a simple collimator. 2. An X-ray source for generating a fan beam and a large number of X-ray detectors arranged in an arc shape or a circumferential shape in a channel direction and arranged in a plurality of rows in a body axis direction of a subject. And an X-ray CT apparatus that reconstructs a CT tomographic image of the subject based on the detection signals of the multi-row detector array. A signal synthesizing means for synthesizing a plurality of sets of detection signals obtained by combining the detection signals of the respective columns with a different number of sets for each channel, and projecting an object corresponding to the plurality of sets based on each output signal of the signal synthesizing means A plurality of data collection units for generating and collecting data; and data processing means for reconstructing CT tomographic images having a plurality of detection widths corresponding to a plurality of sets based on the collected data of each data collection unit. X-ray CT device. 3. An X-ray source for generating a fan beam and a large number of X-ray detectors arranged in an arc shape or a circumferential shape in a channel direction and arranged in a plurality of rows in a body axis direction of a subject. And an X-ray CT apparatus that reconstructs a CT tomographic image of the subject based on a detection signal of the multi-row detector array. A plurality of data collection units that respectively generate and collect the projection data of the subject based on the detection signals of each column, and a plurality of sets of collection data obtained by combining the collection data of each data collection unit with a different number of sets. Data processing means for reconstructing CT tomographic images having a plurality of detection widths corresponding to a plurality of sets by combining for each channel.
Line CT device. 4. An X-ray source for generating a fan beam and a number of X-ray detectors arranged in an arc shape or a circumferential shape in a channel direction and arranged in a plurality of rows in a body axis direction of a subject. And a multi-row detector array facing each other with the subject interposed therebetween, and an X-ray CT apparatus imaging method for reconstructing a CT tomographic image of the subject based on detection signals of the multi-row detector array. For each view to be imaged, each projection data corresponding to a different detection width in the body axis direction of the subject is simultaneously detected and collected, and a CT tomogram having a plurality of detection widths corresponding to each is reconstructed. An imaging method of an X-ray CT apparatus.