JP2001120534A - Multislice type x-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of efficiently taking in slice directional measuring data of a multislice type X-ray detector. SOLUTION: A switch circuit is arranged between the multislice type X-ray detector and a detecting circuit part, and an intake range of measuring data measured by an X-ray detecting element (N channels × N slices) of the X-ray detector is controlled by the switch circuit in response to the size of FOV. At this time, a data intake quantity to the detecting circuit part is restricted to a half, for example, N × Y (=M/2). Since the FOV is small in an illustrated example, a channel directional measuring range is set to N/2 channel of a half, and a slice directional measuring range is set to 2Y of two time instead to be thereby controlled by the switch circuit so as to respectively take measuring data equivalent to one channel of the X-ray detector by a Y slice quantity in order in the detecting circuit part by separating dividing the measuring data into two times so that N × Y data is taken in by intake of N times in total.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus, and more particularly to an X-ray CT apparatus having a multi-slice type X-ray detector capable of simultaneously measuring image data of a plurality of slices.

[0002]

2. Description of the Related Art In recent years, as an X-ray detector used in an X-ray CT apparatus, a solid-state detector using a scintillator has become mainstream. An arrayed multi-slice X-ray detector has been used.

In a multi-slice type X-ray detector, X-ray detection elements including a scintillator and a light detection element such as a silicon photodiode are two-dimensionally arranged in a channel direction and a slice direction. This multi-slice type X
In line detectors, to accommodate various slice thicknesses,
In many cases, X-ray detection elements for 2 to tens of slices are arranged in the slice direction, and X-ray detection elements in those slice directions are combined to obtain image data of a desired slice thickness and a desired number of slices. At the same time.

In a multi-slice X-ray detector having M channels and N slices, M × N X-ray detection elements are arranged. If the detection circuit unit is provided to cope with this, a large number of detection circuit elements of the detection circuit unit are required, and the amount of data transmitted to the image processing apparatus becomes enormous. For this reason, in the conventional devices, the number of detection circuit elements and / or transmission circuits that can be operated simultaneously is reduced.

Next, an example of the prior art of the present invention will be described.
This will be described with reference to FIGS. This prior art is a patent application filed by the applicant of the present invention in Japanese Patent Application No. 11-130600, “Multi-slice X-ray CT apparatus”. FIG. 13 is a block diagram showing the entire system of the multi-slice type X-ray CT apparatus of the present embodiment. FIG. 14 is a view showing the slice thickness using a multi-slice type X-ray detector having an X-ray detection element example divided into eight in the slice direction. FIG. 15 is a block diagram showing a method of processing signals when measuring 1.25 mm × 4 slices, and FIG. 15 is a block diagram similarly showing measuring a slice thickness of 2.5 mm × 4 slices. Hereinafter, the configuration of the entire system will be described with reference to FIG. 13, and a method of processing the measurement data in the slice direction will be described with reference to FIGS.

In FIG. 13, an X-ray CT apparatus is a scanner.
The system comprises three units: an operation console 64, and an image processing device (also referred to as an image processing unit) 3. A scanner rotating plate 5 is supported at the center of the scanner 1, and an X-ray tube 8 and a multi-slice X-ray detector 9 face each other across an opening 7 provided at the center of the scanner rotating plate 5. It is installed. X
An X-ray beam collimator 12 for narrowing the X-ray beam in the slice direction and the channel direction is arranged on the front surface of the tube 8.

In the measurement by the X-ray detector 9, an X-ray radiated from the focal point of the X-ray tube 8 is irradiated on the object while the object is inserted into the opening 7 and the scanner rotating plate 5 is rotated. The measurement is performed by measuring the transmitted X-ray dose from each direction of the subject. At this time, the X-ray beam from the focal point of the X-ray tube 8 is restricted in thickness in the slice direction and width in the channel direction by the X-ray beam collimator 12. The output signal (measurement data) from the X-ray detector 9 is amplified to an appropriate level by the amplifier circuit 72, then converted from analog to digital, and sent to the image processing device 3.

The console 64 includes a keyboard 21, a scan condition setting circuit 22, an image display device 30, and the like.
Control, display of a slice image of the subject, and the like. The scan conditions of the scanner 1 input from the keyboard 21 are input to the scan condition setting circuit 22. In this example, based on the information about the slice thickness in the scan conditions, the slice configuration signal (information indicating the slice thickness × the number of slices) 74 is sent to the scanner 1 and the image addition signal 75 is sent to the image processing device 3.
Respectively.

The slice configuration signal 74 is received by the scanner control circuit 23 of the scanner 1, where the slice configuration signal 74
A collimator aperture control signal 66 and a detector switch switching control signal (hereinafter, referred to as a switch control signal) 70 are generated based on this. The respective signals 66 and 70 are sent to the X-ray beam collimator 12 and the X-ray detector 9, and according to the scanning conditions,
As described later, the slice thickness of the X-ray beam and the switching condition of the switch circuit 69 for the output signal of the X-ray detection element 62 in the slice direction in the X-ray detector 9 are set. X-ray detector
The output from 9 is amplified by an amplifier circuit 72 and then subjected to analog-to-digital conversion and sent to the image processing device 3 as measurement data 35 for a plurality of slices.

The image processing apparatus 3 includes an image reconstruction circuit 28,
The image addition circuit 73, the magnetic disk device 29, and the like are included.
In the image processing device 3, the measurement data 35 sent from the scanner 1 is converted by the image reconstruction circuit 28 into slice images at a plurality of slice positions corresponding to the arrangement of the X-ray detection elements 62 of the X-ray detector 9 in the slice direction. After being created, the plurality of slice images are sent to the image adding circuit 73. Image addition circuit
At 73, the addition processing between the reconstructed slice images is performed in accordance with the image addition signal 75 sent from the scan condition setting circuit 22 of the console 64. The final image data 36 thus obtained is sent to the image display device 30 of the console 64 and stored in a storage device such as the magnetic disk device 29.

Next, a method of processing the measurement data measured by the scanner 1 will be described. Fig. 14 shows the slice direction.
Four X-ray detectors at the center of the eight X-ray detectors
Similarly, FIG. 15 shows a case where an X-ray beam is incident on 62 and measurement data for four slices is output.
It shows a method of processing measurement data when an X-ray beam is incident on the whole and measurement data summarized for four slices is output. In both figures, only the slice direction is shown,
The components in the channel direction are omitted since the same components as those shown in the figure are continued.

In FIG. 14, an X-ray radiated from a focal point of an X-ray tube is focused by a slice-direction collimator 13 into an X-ray beam 60 having a slice thickness of 1.25 mm × 4 slices. The light enters the scintillators 63 of the four X-ray detection elements 62 at the center of the detection element array 61. In the figure, the X-ray beams for four slices are 60A, 60B, 60C and 60D.
It is shown divided into four beams. This X-ray beam 60
The slice thickness is controlled by a collimator aperture control signal 66 from the scan condition setting circuit 22 of the control console 64.

Output signals from the photodiodes 67 of the four X-ray detecting elements 62 at the center are input to a switch circuit 69 via four wires 68. The bold line in the rectangular frame indicating the switch circuit 69 indicates how the inputs of the switch circuit 69 are combined and output based on the switch control signal 70 from the scan condition setting circuit 22. The four output signals of the photodiode 67 input to the switch circuit 69 are sent to the four amplifier circuits 72 of the signal amplification unit 71 as they are, and after amplification, the four output signals of the image processing unit 3 at the subsequent stage are output.
The image data is sent to the image reconstructing circuits 28 to reconstruct four slice images. Thereafter, the four images are output as they are without performing the image addition processing. The image obtained here is the X-ray detection element 62 on which the X-ray beams 60A to 60D are incident.
5 is an image having a slice thickness of 1.25 mm corresponding to FIG.

In FIG. 15, an X-ray beam 60 incident on an X-ray detecting element array 61 is fully opened by a slice-direction collimator 13 so that eight X-ray detecting elements 6 in a slice direction are provided.
(2) Spread to the entire thickness and enter all eight scintillators (63). The switch circuit 69 is set by the switch control signal 70 so that the output signals of the photodiodes 67 are collectively taken out for every two elements and sent to the four amplifying circuits 72. The output signal of the amplification circuit 72 is reconstructed into four slice images by the image reconstruction circuit 28, and is output as it is without performing image addition. Each image is an image having a slice thickness of 1.25 mm × 2 = 2.5 mm corresponding to the X-ray detection elements 62 for the two elements on which the X-ray beams 60A to 60D are incident.

[0015]

In the above prior art example, the output of the switch circuit 69 in the slice direction of the X-ray detector is reduced to four, so that only four slices of measurement data are taken in at the same time. Can not do. For this reason, when the slice thickness is large, the X-ray measurement data of the entire region is used from the central portion to the peripheral portion in the slice direction. However, when the slice thickness is small, the X-ray measurement data at the central portion in the slice direction is used. Only data is used.

As described above, when the X-ray detector is a multi-slice type X-ray detector, even if an X-ray beam having a large width in the slicing direction can be incident on the X-ray detector, the X-ray detector can be used in the slice direction. Can extract only a part of the measurement data, so the X-ray and measurement data in the range where the measurement data cannot be extracted are wasted,
After all, the X-ray beam must be focused also in the slice direction. This means that useless X-rays are generated in terms of X-ray generation efficiency.

In consideration of the above, in the present invention, the multi-slice X-ray C which can efficiently acquire the measurement data in the slice direction of the multi-slice X-ray detector is provided.
It is intended to provide a T device.

[0018]

In order to achieve the above object, a multi-slice X-ray CT apparatus according to the present invention comprises an X-ray source and a plurality of X-ray detecting elements arranged in both a channel direction and a slice direction. A multi-slice type X-ray detector, an X-ray collimator for limiting the width in the channel direction and the thickness in the slice direction of the X-ray beam emitted from the X-ray source,
A detection circuit that performs pre-processing of measurement data of the X-ray detector, a transmission circuit that transmits an output of the detection circuit to the image processing device, an image processing device that reconstructs a CT image based on the measurement data, and an X-ray source. In a multi-slice X-ray CT apparatus including an X-ray detector arranged and mounted facing each other, a scanning mechanism that rotates around the subject, and a control device that controls each device, the detection circuit includes: The number of detection circuit elements equal to or less than the number of X-ray detection elements of the X-ray detector, and between the X-ray detector and the detection circuit, the output of the X-ray detection element is sent to the detection circuit element. A switch circuit comprising a plurality of switch elements to be connected, and / or a transmission selection mechanism for selecting an output from the detection circuit element and transmitting the output to the transmission circuit is provided between the detection circuit and the transmission circuit. And the switch circuit Connection by pitch elements, and / or selection of the detection circuit element according to the transmission selection mechanism is performed corresponding to the size of the effective field of view or the object is measured (claim 1).

In this configuration, the measurement data measured by the X-ray detection element of the multi-slice type X-ray detector is taken into the image processing device between the X-ray detector and the detection circuit. It is controlled by a switch circuit and / or a transmission selection mechanism provided between the detection circuit and the transmission circuit, and the control is performed according to the effective visual field to be measured or the size of the subject. Therefore, as with the prior art, the measurement data acquisition range is not constant, as in the prior art, and varies according to the effective field of view or the size of the subject. Accordingly, the acquisition range of the measurement data in the slice direction also changes, so that efficient data measurement can be performed.

In the multi-slice type X-ray CT apparatus according to the present invention, of the measurement data measured by the X-ray detection element of the X-ray detector, the switch element of the switch circuit may be used as the detection circuit element of the detection circuit. Regarding the measurement data connected or / and selected by the transmission selection mechanism and sent to the transmission circuit, the product of the number of measurement data in the channel direction and the number of measurement data in the slice direction is constant (claim 2). . In this configuration, the product of the number of measurement data in the channel direction and the number of measurement data in the slice direction in the working range of the measurement data of the X-ray detector is fixed.
When the number of measurement data in the channel direction is small, the number of measurement data in the slice direction can be increased.

In the multi-slice type X-ray CT apparatus according to the present invention, the measurement data of the X-ray detection element connected by a switch element of the switch circuit or / and selected by the transmission selection mechanism may be used in a channel direction. Is changed according to the effective visual field to be measured or the size of the subject (claim 3). In this configuration, X
Since the number of measurement data in the channel direction of the line detector is changed in accordance with the effective field of view or the size of the subject, there is no need to take extra measurement data in the channel direction, and the channel Since the number of measurement data in the slice direction can be increased by an amount corresponding to the reduction in the number of measurement data, efficient data measurement can be performed.

In the multi-slice X-ray CT apparatus according to the present invention, the width of the aperture of the X-ray collimator in the channel direction is further limited according to the effective visual field of measurement or the size of the subject. In this configuration, the width of the aperture of the X-ray collimator in the channel direction is limited, and the X-ray beam is made to correspond to the effective field of view or the size of the subject. Can be matched with the data measurement range in the channel direction of the X-ray detector. Without irradiating the subject with useless X-rays,
X-ray beams can be used effectively.

In the multi-slice type X-ray CT apparatus according to the present invention, when the subject protrudes from the measurement area in the channel direction, the X-ray attenuation data in the area where the subject protrudes and cannot be measured is predicted. It is provided with a protrusion correction means for obtaining measurement data corrected for the protrusion region. In this configuration, by limiting the measurement area in the channel direction of the X-ray detector, even when the subject is out of the measurement area in the channel direction, the measurement of the protruding portion of the subject is corrected by the overflow correction means. Since data can be obtained, a slice image including a protruding portion of the subject can be reconstructed by using the corrected measurement data.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an entire system of a multi-slice X-ray CT apparatus of the present invention, FIG. 2 is a diagram showing an outline of a configuration of a main part of the multi-slice X-ray CT apparatus of the present invention, and FIG. FIG. 4 is a diagram showing an example of a data acquisition range of measurement data in the multi-slice X-ray CT apparatus of the present invention. The configuration of the entire system of the X-ray CT apparatus of the present invention and the gist of the present invention will be described with reference to FIGS.

In FIG. 1, the configuration of the whole system of the multi-slice type X-ray CT apparatus of the present invention is a modification of the prior art example of FIG. 13, and has a configuration similar to that of FIG.
The major difference between the present invention and the prior art example lies in the technique of capturing measurement data.

First, the configuration of the whole system of the multi-slice X-ray CT apparatus according to the present invention will be described with reference to FIG. In FIG. 1, the X-ray CT apparatus includes three units: a scanner 1, a control device 2, and an image processing device 3. The scanner 1 has a scanner rotating plate 5 rotatably supported by a gantry 6. This scanner rotating plate
An X-ray tube 8 and a multi-slice X-ray detector (hereinafter, also referred to as X-ray detector) 9 are mounted on 5 such that they face each other with an opening 7 provided in the center therebetween. On the front surface of the X-ray tube 8, an X-ray beam collimator 12 for narrowing an X-ray beam 11 emitted from the focal point in a slice direction and a channel direction is arranged.

In the X-ray measurement by the X-ray detector 9, the X-ray beam 11 emitted from the focal point of the X-ray tube 8 is applied to the subject inserted into the opening 7 while rotating the scanner rotating plate 5. Irradiation is performed by measuring the transmitted X-ray dose from each direction of the subject. At this time, the X-ray beam 11 is
12 limits the thickness in the slice direction and the width in the channel direction. The output signal from the X-ray detector 9 is amplified to an appropriate level by the detection circuit unit 10, then converted from analog to digital, and transmitted to the image processing device 3.

The control device 2 includes a keyboard 21, a scan condition setting circuit 22, an image display device 30, and the like. The control device 2 controls the scanner 1 and the image processing device 3 and displays a slice image of the subject. The same function as that of the operation console 74 is executed. Scan conditions of the scanner 1 and information for controlling the image processing apparatus 3 are input from the keyboard 21 to the scan condition setting circuit 22. The information input to the scan condition setting circuit 22 includes the size of the subject or the effective field of view (F
The size of OV (Field of View), the connection method between the X-ray detection element of the X-ray detector 9 and the detection circuit unit 10, the connection method between the detection circuit unit 10 and the transmission circuit 16, the aperture of the X-ray beam collimator 12 Information on dimensions, overhang correction method, etc. is included.
Among these pieces of information, information for controlling the scanner 1 is sent to the scanner control circuit 23 as a scanner control signal 37, and information for controlling the image processing apparatus 3 is sent to the image processing apparatus 3 as an image processing control signal 38.

In the scanner control circuit 23 of the scanner 1, based on the scanner control signal 37, a signal for controlling the scanner 1 main body, a collimator aperture control signal 24, a detection circuit switch switching control signal (hereinafter referred to as a switch control signal) 25. , A transmission circuit control signal 26 and the like are generated. The collimator aperture control signal 24 is sent to the X-ray beam collimator 12, and the channel width and slice thickness of the X-ray beam 11 are set according to the scanning conditions. The switch control signal 25 is sent to the X-ray detector 9, and a switch circuit 31 provided between the X-ray detection element constituting the X-ray detector 9 and the detection circuit unit 10.
By controlling the switching of the switches in, the output ranges of the X-ray detector 9 in the slice direction and the channel direction are controlled. Further, the transmission circuit control signal 26 is sent to the detection circuit unit 10, and the transmission selection mechanism 32 provided between the detection circuit unit 10 and the transmission circuit 16 controls the transmission selection mechanism 32, so that the X-ray The output range of the detector 9 in the slice direction and the channel direction is controlled.

In the present invention, when the output from the X-ray detector 9 is taken into the detection circuit section 10, the output range in the slice direction and the channel direction is limited by the switch circuit 31 described above. The signal is amplified by the circuit unit 10, converted from analog to digital, and transmitted to the image processing device 3 through the transmission circuit 16 as measurement data 35 for a plurality of slices. The output from the X-ray detector 9 is
If the output range is not limited when the data is captured, the transmission selection mechanism 32 limits the output range in the slice direction and the channel direction when transmitted from the detection circuit unit 10 to the transmission circuit 16. Is done. The limitation of the output range in the slice direction and the channel direction will be described later in detail.

The image processing apparatus 3 includes a protrusion correction circuit 27
, An image reconstruction circuit 28, a magnetic disk device 29, and the like. The protruding correction circuit 27 is provided for detecting that the object is the X-ray detector 9.
If the measurement data exceeds the measurement range, the measurement data of the protruding portion is calculated as correction data based on the measurement data at the end of the measurement range of the X-ray detector 9. The FOV correction circuit 27 receives the FOV
Alternatively, information for correcting the protrusion based on the size of the subject is input as the image processing control signal 38. The image reconstruction circuit 28 reconstructs a slice image of a plurality of slices based on the measurement data 35 output from the X-ray detector 9. The magnetic disk device 29 stores the image data of the reconstructed slice image.

In the image processing apparatus 3, the measurement data 35 transmitted from the scanner 1 is input to the overflow correction circuit 27,
If necessary, correction measurement data for the protruding portion is created based on the measurement data 35 here. The measurement data 35 that has been subjected to the overflow correction is input to the image reconstruction circuit 28, where a slice image at a plurality of slice positions corresponding to the arrangement of the X-ray detection elements of the X-ray detector 9 in the slice direction is reconstructed. I do. Image data obtained in this way
36 is sent to and displayed on the image display device 30 of the control device 2, and is stored in a storage device such as the magnetic disk 29.

Next, the multi-slice type X-ray CT of the present invention
The acquisition of measurement data by the device will be described with reference to FIGS. FIG. 2 shows a portion related to the import of the measurement data in FIG. FIG. 3 shows two examples according to the conventional example and two examples according to the present invention as examples of the data acquisition range of the measurement data.

In FIG. 2, FIG. 2 (a) shows a device relating to collection and acquisition of measurement data, and FIG. 2 (b) shows a relationship between a control member and a control signal at the time of acquisition of measurement data. , Respectively. In FIG. 2A, the multi-slice type X
The X-ray detector 9 has N channels of X-ray detection elements 15 in the channel direction (arc direction) and M slices of X-ray detection elements 15 in a slice direction orthogonal thereto. It has a detection element 15. Therefore, the multi-slice X-ray detector 9 can collect a maximum of N × M measurement data at each rotation angle (data acquisition angle) of the scanner rotating plate 5.

In the prior art, the transfer rate of the measurement data is N channels in the channel direction and N channels in the slice direction, while the number of X-ray detection elements 15 of the multi-slice type X-ray detector 9 is N × M. For Y channel (Y <
M). That is, although the number of elements in the channel direction is the same as the number N of elements in the channel direction, the slice direction is limited to Y slices smaller than the number M of elements in the slice direction. Therefore, the X-ray beam 11 emitted from the X-ray tube 8 is narrowed down to a slice width of the central Y slice by the slice direction collimator 13 of the X-ray beam collimator 12, and the measurement data of that portion is transferred. Or by narrowing the X-ray beam 11 wider than the Y-slice,
The data is transferred as Y output data per channel, and the total amount of transfer data is N × Y.

On the other hand, in the present invention, the total amount of transfer data is N × Y, which is the same as that of the prior art, but the transfer data amount in the channel direction is variable according to the FOV or the size of the subject. The transfer data amount in the slice direction is made variable accordingly. In other words, if the size of the FOV or the subject is small, transfer the measurement data only in the central portion corresponding to the size of the FOV or the subject in the channel direction, and as the size of the FOV or the subject increases, The transfer range in the channel direction is increased in proportion to the FOV or the size of the subject. With this configuration, when the size of the FOV or the subject is small, more measurement data in the slice direction can be transferred even when the entire slice width is small.

FIG. 3A and FIG. 3B show an example of a data acquisition range of measurement data according to a conventional example.
(C) and FIG. 3 (d) are examples of the data capture range of the measurement data according to the present invention. The data acquisition range of the measurement data in FIG. 3A is N channels in the channel direction and Y slices in the slice direction. In the channel direction, measurement data in the entire range is captured, and in the slice direction, measurement data in a half range (2Y = M) is captured. As a whole, measurement data of the X-ray detection element 15 which is half of the X-ray detector 9 is taken in. Although this example is a conventional example here, it is an example on the boundary between the target range of the present invention and the conventional example.

The data acquisition range of the measurement data in FIG. 3B is N channels in the channel direction and M (= 2Y) slices in the slice direction. The measurement data of the entire range is taken in both the channel direction and the slice direction.
However, in the slice direction, the measurement data for two slices is combined by a switch circuit, so that the number of data in the slice direction is reduced by half to obtain a data amount for Y slices.

The data acquisition range of the measurement data in FIG. 3 (c) is 1 / 2N channel in the channel direction and M (= 2Y) slices in the slice direction. In this example, the FOV
Alternatively, since the size of the subject is about 1/2 of the maximum measurement range in the channel direction of the X-ray detector 9, the capture range of the measurement data in the channel direction is set in accordance with the FOV or the size of the subject. It is 1 / 2N of half of the whole. Conversely, in the slice direction, the data acquisition range can be increased by the proportion of the data acquisition range reduced in the channel direction. Therefore, the data acquisition range in the slice direction is 2Y (= M) slices. is there.

The data acquisition range of the measurement data in FIG. 3B is 2 / 3N channels in the channel direction and 3 / 4M (= 3 / 2Y) slices in the slice direction. In this example, since the size of the FOV or the subject is about 2/3 of the maximum measurement range in the channel direction of the X-ray detector 9, the measurement in the channel direction is performed according to the size of the FOV or the subject. The data acquisition range is 2 / 3N of the whole. The slice direction is equivalent to 3 / 2Y (= 3 / 4M) slices.

In the present invention, the data acquisition of the above measurement data is controlled by control signals 25 and 26 from the control device 2 as shown in FIG. When the output of the X-ray detector 9 of the X-ray detector 9 is sent to the detection circuit section 10, the data capture range of the measurement data is set by switch switching of a switch circuit 31 provided at the connection between the two. Alternatively, when the output of the detection circuit unit 10 is sent to the transmission circuit 16, it is set by the transmission selection mechanism 32 provided at the connection between the two. The former switch circuit 31 is controlled by a switch control signal 25.
The latter is controlled by the transmission circuit control signal 26. In each case, the FOV
Alternatively, control is performed according to the size of the subject.

In FIG. 2B, the detection circuit section 10 includes detection circuit elements 40 corresponding to the number of channels and the number of slices of the X-ray detector 9. The number of the detection circuit elements 40 is usually set smaller than the number of the X-ray detection elements 15 of the X-ray detector 9, and the number of the X-ray detection elements 15 and the detection circuit element 40 is one.
One to one correspondence. The association between the X-ray detection element 15 and the detection circuit element 40 is performed by a switch circuit 31 provided between the X-ray detector 9 and the detection circuit section 10. The switch circuit 31 includes switch elements 41 arranged in the channel direction and the slice direction in association with the X-ray detection element 15, and the operation of the switch circuit 31 is controlled by a switch control signal 25 sent from the control device 2. . The measurement data of the X-ray detector 9 is taken into the detection circuit unit 10 by the switch circuit 31 and subjected to data processing, and then transmitted from the transmission circuit 16 to the image processing device 3.

In the case where a large number of the detection circuit elements 40 are arranged so that the total number of the X-ray detection elements 15 of the X-ray detector 9 and the total number of the detection circuit elements 40 of the detection circuit section 10 correspond one-to-one. , X
No switch circuit 31 is provided between the line detector 9 and the detection circuit unit 10, and a transmission selection mechanism 32 is provided between the detection circuit unit 10 and the transmission circuit 16 to select measurement data to be sent to the transmission circuit 16. I do. The detection circuit element 40 of the detection circuit section 10 is the same as the X-ray detection element 15.
Since the correspondence is one-to-one, the transmission selection mechanism 32 selects only necessary ones of the measurement data output from the detection circuit element 40 in the channel direction and the slice direction and transmits them to the transmission circuit 16. The transmission sorting mechanism 32 includes a switch circuit 31
Similarly, the transmission circuit control signal 26 sent from the control device 2
Is controlled by

In the above description, the setting of the measurement data acquisition range of the X-ray detector 9 is performed by the switch circuit 31,
The case where the transmission is performed by the transmission selection mechanism 32 has been described. However, the present invention is not limited to this.

The control example of the above switch circuit 31 is shown in FIGS.
This will be described with reference to FIG. The explanation is for Fig. 3 (a)-Fig. 3
(D) will be described with reference to FIGS. FIGS. 4 and 5 are directed to FIGS. 3 (a) and 3 (b) of the conventional example. Figure 4
Is for explaining the first conventional example of the control for taking in the measurement data in the slice direction. The upper diagram shows the same figure as FIG. 3A, and the lower diagram shows the measurement data in the slice direction for four channels. 9 shows a procedure of control of switchover of taking-in. The horizontal direction in the upper diagram shows the channel direction of the X-ray detector 9, and the vertical direction shows the same slice direction. N elements are arranged in the channel direction and 8 elements (M = 8) are arranged in the slice direction. In this example, the X-ray beam 11
X-ray detector 1 for 4 slices at the center
X-ray measurement is performed by 5 and measurement data for four slices (Y = 4) is output. 4 to 7, the upper figures are symmetrical with respect to the center channel, and therefore, in the following description of the measurement data acquisition control, only the right side from the center will be described. Since the left side from the center is the same as the right side, the description is omitted.

The lower diagram shows four channels (channel numbers N / 2 + 1, N / 2 + 2, N / 2 +) on the right side of the center in the channel direction.
3, (N / 2 + 4) switch switching control of the switch circuit 69 is shown. In this example, since N pieces of measurement data are output in the channel direction and Y pieces (Y = 4) in the slice direction, all the measurement data is output and transferred. The control of the data output in the channel direction is performed in order from the left side with the smaller channel number to the right side with the larger channel number.

First, the X-ray detection element group 43a for one channel with the channel number N / 2 + 1 is composed of eight X-ray detection elements 15, but the measurement data exists at the center. The number of slices is 4 slices from 3 to 6.
The switch elements 41 of the switch element group 45a for one channel of the switch circuit 31 are connected to the respective X-ray detection elements 15 of the X-ray detection element group 43a for one channel. The detection circuit elements 40 of the detection circuit element group 44a for the channels are connected. Switch element group 4 of channel number N / 2 + 1 of switch circuit 31 in such a connection state
For 5a, by sending the switch control signal 25 from the control device 2, only the output of the X-ray detection elements 15 of the slice numbers 3 to 6 where the measurement data exists is sent to the detection circuit unit 10,
The switch circuit 31 operates so that no output is sent to the X-ray detection elements 15 of the other slices. As a result, the measurement data collected by the X-ray detection element group 43a having the channel number N / 2 + 1 is sent to the detection circuit element group 44a having the channel number N / 2 + 1 of the detection circuit section 10.

Similarly, X-ray detector element groups 43b, 43c, 43d of channel numbers N / 2 + 2, N / 2 + 3, N / 2 + 4 of X-ray detector 9
The measurement data collected by the switch circuit 31 detects the channel numbers N / 2 + 2, N / 2 + 3, and N / 2 + 4 of the detection circuit unit 10 by the operation of the switch element groups 45b, 45c, and 45d of the switch circuit 31. Circuit element group 44
b, 44c, 44d.

FIG. 5 is a diagram for explaining a second conventional example of the control for taking in measurement data in the slice direction. The upper diagram shows the same diagram as FIG. 3B, and the lower diagram shows slices for four channels. Fig. 7 shows a procedure of a control for switching a fetching switch of measurement data in a direction. In this example, the slice direction is narrowed so that the slice direction collimator 13 is fully opened and the X-ray beam 11 is incident on all the X-ray detection elements 15 in the slice direction.
X-ray measurement is performed by all the X-ray detection elements 15 in the slice direction of the X-ray detector 9, and measurement data for eight slices (M = 8) is output.

On the other hand, in the detection circuit section 10, 1
Since only four slices (Y = 4) of data can be received per channel, the switch circuit 31
The outputs of the X-ray detection elements 15 for two slices are combined as one data, and four data are output per channel. For example, in the channel 43a of the channel number N / 2 + 1, the four switch elements 41 of the switch element group 45a of the switch circuit 31 are connected to the X-rays of slice numbers 1 and 2, 3 and 4, 5 and 6, 7 and 8 By combining the outputs of the detection elements 15 into outputs one by one, the data is sent to the four detection circuit elements 40 of the detection circuit element group 44a of the detection circuit section 10 as four data. The same applies to other channel numbers N / 2 + 2, N / 2 + 3, and N / 2 + 4.

FIG. 6 shows a multi-slice type X-ray C of the present invention.
The first of the acquisition control of the measurement data in the slice direction of the T device
The upper part of FIG. 3C illustrates the same figure as FIG. 3C, and the lower part of FIG. 3 illustrates the procedure of switching control of the acquisition switch of the measurement data in the slice direction for four channels. In this embodiment, the size of the FOV or the subject is small,
The measurement range in the channel direction of the X-ray detector 9 is N /
This is the case of two channels. In this case, the acquisition range of the measurement data of the X-ray detector 9 is the number of channels × the number of slices.
Since up to N × Y (= N × M / 2) is possible, it is possible to capture measurement data in the entire range in the slice direction of the X-ray detector 9. Therefore, in the lower diagram, X for one channel of channel numbers N / 2 + 1, N / 2 + 2, N / 2 + 3, N / 2 + 4
The measurement data of the X-ray detection elements 15 of all (M = 8) of the line detection element groups 43a, 43b, 43c, 43d are taken.

On the other hand, since the number of detection elements per channel is limited to M / 2 on the detection circuit section 10 side, measurement data between the X-ray detection element 15 and the detection circuit element 40 is Is controlled by the switch circuit 31.

In the lower diagram, first, the lower half of the X-ray detector element group 43a of the X-ray detector 9 with the channel number N / 2 + 1 is shown.
Channel number N of four X-ray detection elements 15 and detection circuit section 10
The four detection circuit elements 40 of the / 2 + 1 detection circuit element group 44a are the switch element groups 45a of the channel number N / 2 + 1 of the switch circuit 31.
Connected by four switch elements 41 in the lower half of
The measurement data collected by the four lower X-ray detection elements 15 in the lower half of the X-ray detection element group 43a is taken into the detection circuit element group 44a. Next, the four detection circuit elements 40 of the X-ray detection element 15 in the upper half of the X-ray detection element group 43a and the detection circuit element group 44b of the channel number N / 2 + 2 of the detection circuit section 10 are connected to the switch element group 45.
connected by four switch elements 41 in the upper half of a,
The measurement data collected by the four upper X-ray detection elements 15 of the X-ray detection element group 43a is taken into the detection circuit element group 44b. Next, the X of the channel number N / 2 + 2 of the X-ray detector 9 is
Four lower X-ray detection elements 15 in the lower half of the line detection element group 43b and the detection circuit element group 44c of the channel number N / 2 + 3 of the detection circuit section 10
The four detection circuit elements 40 are connected by the lower half four switch elements 41 of the switch element group 45b of the channel number N / 2 + 2 of the switch circuit 31, and the lower half of the X-ray detection element group 43b The measurement data collected by the four X-ray detection elements 15 is taken into the detection circuit element group 44c. Hereinafter, as shown in FIG. 6, up to the channel number N / 2 + N / 4 of the X-ray detector 1,
The same measurement data is acquired.

FIG. 7 shows a multi-slice X-ray C of the present invention.
The second of the acquisition control of the measurement data in the slice direction of the T device
The upper part of FIG. 3D illustrates the same figure as FIG. 3D, and the lower part of FIG. 3 shows the procedure of the switch control for taking in measurement data in the slice direction for four channels. In the present embodiment, the case where the size of the FOV or the subject is medium and the measurement range in the channel direction of the X-ray detector 9 is 2N / 3 channel at the center. In this case, the acquisition range of the measurement data of the X-ray detector 9 is N × Y by the number of X-ray detection elements.
Therefore, it is possible to capture measurement data in the range of 3Y / 2 (= 3M / 4) in the slice direction of the X-ray detector 9. Therefore, in the lower figure, the X-ray detection element groups 43a, 43b, 43c, 43d for one channel of channel numbers N / 2 + 1, N / 2 + 2, N / 2 + 3, N / 2 + 4 The measurement data of the 3Y / 2 (= 3M / 4 = 6) X-ray detection elements 15, that is, the X-ray detection elements 15 of slice numbers 2 to 7 are taken in.

On the other hand, on the detection circuit section 10 side, the number of detection circuit elements 40 per channel is limited to M / 2 (= 4), so that the X-ray detection element 15 and the detection circuit element 40
The acquisition of the measurement data between is controlled by the switch circuit 31 as follows.

In the lower diagram, first, four X-ray detecting elements 15 of slice numbers 2 to 5 of the X-ray detecting element group 43a of channel number N / 2 + 1 of the X-ray detector 9, and a detecting circuit section The four detection circuit elements 40 of the detection circuit element group 44a of the channel number N / 2 + 1 of ten are the four slice numbers 2 to 5 of the switch element group 45a of the switch circuit 31 of the channel number N / 2 + 1. And the measurement data collected by the four X-ray detection elements 15 of slice numbers 2 to 5 of the X-ray detection element group 43a are taken into the detection circuit element group 44a. Next, two X-ray detection elements 15 of slice numbers 6 and 7 of the X-ray detection element group 43a and two X-rays of slice numbers 2 and 3 of the X-ray detection element group 43b of channel number N / 2 + 2 Line detection element 15,
Detection circuit element group 4 of channel number N / 2 + 2 of detection circuit section 10
The four detection circuit elements 40 of 4b are two switch elements 41 of slice numbers 6 and 7 of the switch element group 45a of the switch circuit 31.
Is connected to two switch elements 41 of slice numbers 2 and 3 of a switch element group 45b of channel number N / 2 + 2, and X
The measurement data collected by the four X-ray detection elements 15 of the slice numbers 6 and 7 of the line detection element group 43a and the slice numbers 2 and 3 of the X-ray detection element group 43b are taken into the detection circuit element group 44b. Next, slice numbers 4 to 7 of the X-ray detection element group 43b are
Four X-ray detection elements 15 and four detection circuit elements 40 of the detection circuit element group 44c of the channel number N / 2 + 3 of the detection circuit section 10
Are connected by four switch elements 41 of slice numbers 4 to 7 of the switch element group 45b, and the X-ray detection element group 43b
The measurement data collected by the four X-ray detection elements of slice numbers 4 to 7 are taken into the detection circuit element group 44c. Hereinafter, as shown in FIG. 7, the channel number of the X-ray detector 9 will be described.
The same measurement data is acquired up to N / 2 + N / 3.

In the case of the present embodiment, with respect to the data acquisition range of the measurement data of the X-ray detector 9, the measurement range in the channel direction of the X-ray detector 9 is increased or decreased in accordance with the FOV or the size of the subject. In response to this, the measurement range in the slice direction is reduced or increased, and the switch circuit 31 is controlled so as to take in a certain amount of measurement data as a whole. Therefore, when the size of the FOV or the subject is large, the measurement data acquisition range is not much different from that of the prior art.
If V or the size of the subject is small, the number of measurement data in the channel direction decreases,
Can be sorted in the slice direction, so that the number of pieces of measurement data in the slice direction is much larger than in the prior art, and efficient data measurement can be performed.

Next, an example of control of the transmission selection mechanism 32 will be described.
This will be described with reference to FIGS. The explanation is for Fig. 3 (a) and Fig. 3.
(C) will be described with reference to FIGS. 8 and 9, respectively. In the case of this example, since the total number N × M of the X-ray detection elements 15 of the X-ray detector 9 is equal to the total number of the detection circuit elements 40 of the detection circuit section 10, the X-ray Regarding the connection between the detector 9 and the detection circuit unit 10, the switch switching control by the switch circuit 31 is not required, and the connection is directly made. Instead, a transmission selection mechanism is provided between the detection circuit unit 10 and the transmission circuit 16.
32 is provided, and the connection between them is made by receiving the transmission circuit control signal 26 from the control circuit 2. The transmission circuit 16
Is configured to sequentially transmit the measurement data selected by the transmission selection mechanism 32 and sent to the transmission circuit 16 to the image processing device 3.

FIG. 8 is a diagram for explaining a third example of the conventional control for taking in measurement data in the slice direction. The upper diagram shows the same diagram as FIG. 9 shows a control procedure of the transmission selection mechanism 32 for taking in measurement data in the slice direction. In the case of this example, the X-ray detector 9 has N elements in the channel direction and M (= 8) X-ray detection elements 15 arranged in the slice direction. The detecting element 15 is configured such that the channel direction is all channels, and the slice direction is half a slice (4 at the center).
Slice). Since each X-ray detection element 15 of the X-ray detector 9 and each detection circuit element 40 of the detection circuit section 10 are directly connected, they correspond one-to-one.

First, the channel number N / 2 + of the X-ray detector 9
Looking at the X-ray detection element group 43a for one channel of 1, measurement data is collected by the X-ray detection elements 15 of slice numbers 3 to 6. Accordingly, the measurement data also exists in the detection circuit elements 40 of slice numbers 3 to 6 for the detection circuit element group 44a for one channel of the channel number N / 2 + 1 of the detection circuit section 10. The measurement data preprocessed by the four detection circuit elements 40 of the slice numbers 3 to 6 in the detection circuit element group 44a of the detection circuit section 10 are channel numbers.
The detection circuit elements 40 of slice numbers 3 to 6 of the detection circuit element group 44a are selected by the transmission selection mechanism 46a corresponding to N / 2 + 1, and are sequentially sent to the transmission circuit 16a and transmitted to the image processing device 3. Is done. Next, the measurement data collected by the X-ray detection elements 15 of slice numbers 3 to 6 of the X-ray detection element group 43b of the X-ray detector 9 having the channel number N / 2 + 2 is the channel number of the detection circuit unit 10. After being sent to the detection circuit elements 40 of the slice numbers 3 to 6 in the N / 2 + 2 detection circuit element group 44b and pre-processed, it is detected by the transmission selection mechanism 46b corresponding to the channel number N / 2 + 2. By selecting the detection circuit elements 40 of the slice numbers 3 to 6 of the circuit element group 44b, the detection circuit elements 40 are sequentially sent to the transmission circuit 16b and transmitted to the image processing device 3. Thereafter, as shown in FIG. 8, the same measurement data is fetched and transmitted up to the channel number N of the X-ray detector 9.

FIG. 9 shows a multi-slice type X-ray C of the present invention.
Third control of acquisition of measurement data in the slice direction of T device
The upper diagram shows the same diagram as FIG. 3 (c), and the lower diagram shows the control procedure of the transmission selection mechanism 32 for acquiring measurement data in the slice direction for four channels. I have. In the present embodiment, the size of the FOV or the subject is small, and the measurement range in the channel direction of the X-ray detector 9 is the central N / 2 channel. In this case, the acquisition range of the measurement data of the X-ray detector 9 is N / 2 channels,
The number of slices is M.

In the lower diagram, first, in the X-ray detector element group 43a of the channel number N / 2 + 1 of the X-ray detector 1, all (8
Measurement data is collected by the X-ray detection elements 15, and the measurement data is the channel number of the detection circuit unit 10.
The signals are sent to the eight detection circuit elements 40 of the N / 2 + 1 detection circuit element group 44a, and preprocessed. All the eight detection circuit elements 40 of the detection circuit element group 44a are selected by the transmission selection mechanism 46a corresponding to the channel number N / 2 + 1, so that the measurement data preprocessed by the detection circuit element group 44a is , Sequential transmission circuit 1
6a, and transmitted to the image processing device 3. At this time, since the number of measurement data per channel is 2Y (= 8), the selection and transmission circuit 16a by the transmission selection mechanism 46a
Transmission takes twice as long.

Hereinafter, the channel number N / 2 + of the X-ray detector 1 will be described.
2, N / 2 + 3 and N / 2 + 4 are similarly subjected to measurement data acquisition processing. This process is performed up to the channel number N / 2 + N / 4. The processing range in the channel direction is N / 2 channels, which is half of all channels, but as described above, the processing time per channel has been doubled, so the overall processing time is the same as the example in FIG. Will be the same.

According to the present embodiment, in the first embodiment of the present invention, the range of taking in the measurement data is controlled by the switch circuit 31 provided between the X-ray detector 9 and the detection circuit section 10. On the other hand, the same control is performed by the transmission selection mechanism 32 provided between the detection circuit unit 10 and the transmission circuit 16 to fulfill the same role. As a result, in the present embodiment, similarly to the first embodiment, when the size of the FOV or the subject is small and the measurement data in the channel direction may be small, the detection circuit unit 10 for that may be used. The number of pieces of measurement data that can be distributed in the slice direction and can be simultaneously captured can be increased, and efficient data measurement can be performed.

Next, means for changing the size of the FOV will be described. Means for changing the size of the FOV include a method in which the operator of the apparatus determines and changes the size of the FOV, and a method in which the size of the subject is measured in advance by preliminary X-ray irradiation or the like, and the measurement result is used. There is a method of determining the size of the FOV based on the information. The same applies to the case of changing the size of the subject.

When the size of the FOV is set small, when the subject is not located at the center of the X-ray detector 1 in the channel direction, or when the subject is larger than expected, X The measurement range of the measurement data by the line detector 9 becomes insufficient, which causes an artifact. In these cases, based on the measurement data of the measurement range of the X-ray detector 9, the protruding area of the subject is estimated and the protruding correction is performed (protruding correction will be described later).

FIG. 10 shows a flowchart of an example of the sequence of the X-ray CT apparatus when the operator determines the size of the FOV. Hereinafter, the contents of the procedure of FIG. 10 will be described with reference to FIG. 1 and FIG. First, in step 101, the size of the FOV determined by the operator is input from the keyboard 21 of the control device 2 to the scan condition setting circuit 22.

In step 102, based on the magnitude of FOV,
The connection between the X-ray detection element 15 of the X-ray detector 9 and the detection circuit element 40 of the detection circuit section 10 is changed. Information on the size of the FOV is sent from the scan condition setting circuit 22 to the scanner control circuit 23 as a scanner control signal 37 together with other information, and is further transmitted as a switch control signal 25 between the X-ray detector 9 and the detection circuit unit 10. Is sent to the switch circuit 31 provided in the. The switch circuit 31 is provided between the X-ray detectors 15 arranged in the X-ray detector 9 in the channel direction and the slice direction.
Of the channel direction corresponding to the size of X and the slice direction range X defined by the channel direction range
Only the line detection element 15 is connected to the detection circuit element 40 of the detection circuit section 10.

In step 103, based on the magnitude of FOV,
The X-ray beam collimator 12 changes the width of the X-ray beam 11 in the channel direction and the thickness in the slice direction. Information about the FOV size is sent from the scanner control circuit 23 to the X-ray beam collimator 12 as a collimator aperture control signal 24,
The collimator aperture size is changed in accordance with the size of the X-ray beam, and the channel direction width and slice direction thickness of the X-ray beam 11 are changed.

In step 104, since the subject may protrude from the FOV size determined above, the correction amount is determined in advance. The details of the overflow correction will be described later. In this step, what kind of overhang correction is to be performed when the object runs out of the subject is calculated.
Perform in.

In step 105, the scanner 1 is operated to irradiate the subject with the X-ray beam 11, and the X-ray transmission data is measured by the X-ray detector 9. The range of taking in the measurement data is controlled by the switch circuit 31 which has received the switch control signal 25. The measurement data 35 is taken into the detection circuit section 10, where it is pre-processed and transmitted from the transmission circuit 16 to the image processing device 3.

In step 106, the measurement data 35 sent to the image processing device 3 is subjected to various corrections such as sensitivity correction and protrusion correction. Extrusion correction is a protruding correction circuit
It is performed at 27. In the protrusion correction, the amount of X-ray attenuation due to X-ray transmission is checked based on the measurement data at both ends of the FOV, and it is determined whether or not protrusion has occurred.
If the protrusion has occurred, in step 104, the protrusion is corrected in accordance with a predetermined correction method.

In step 107, the image reconstruction circuit 28 reconstructs a slice image of a plurality of slices using the measurement data subjected to various corrections. In step 108, the image data 36 of the slice image reconstructed in step 107 is sent to the image display device 30 of the control device 2 and displayed thereon. The same image data 36 is recorded and stored in a storage device such as the magnetic disk device 29 of the image processing device 3.

In the above description, the size of the FOV is set by the operator in step 101, but separately from this, preliminary X-ray irradiation is performed on the subject to reduce X-ray attenuation. The amount may be measured, the approximate size of the subject is determined based on the measurement data, and the size of the FOV may be set based on the result.

Next, the extension correction will be described. Figure
11 shows an example of the overflow of the measurement data, FIG. 12
Shows an example of the correction of the overflow of the measurement data.
In FIG. 11, the horizontal axis represents the arrangement of the X-ray detection elements in the channel direction of the X-ray detector 9, and the vertical axis represents the rotation angle (view angle) of measurement data collection of the X-ray detector 9. This rotation angle corresponds to the rotation angle of the scanner rotating plate. Channels P1 and P2 in the horizontal axis direction in FIG. 11 are boundary points of a range in which measurement data in the channel direction of the X-ray detector 9 is set in accordance with the FOV size. That is, channel P1
The area between the channel P2 and the channel P2 is within the measurement data acquisition range, the left side of the channel P1 and the right side of the channel P2 are outside the measurement data acquisition range, and the measurement data protruding area.

In the example shown in FIG. 11, there are three protruding areas A, B and C indicated by oblique lines. This protruding area differs depending on the view angle. In the case of the view angle θ shown in the figure, as shown by the view angle θ line 48, the area protruding to the left of the channel P1
A exists, and no protruding area exists on the right side of the channel P2. As described above, the protruding area changes depending on the View angle, but the protruding area is normally offset to one of the left side of the channel P1 or the right side of the channel P2 with respect to the measurement data acquisition range (between the channels P1 and P2). .

In FIG. 12, FIG. 12 (a) shows a first example of out-of-plane correction, and FIG. 12 (b) shows a second example of out-of-plane correction. The first overhang correction example in FIG. 12A corrects the measurement data of the overhang portion by linear approximation. Figure
In FIG. 12A, the horizontal axis indicates the arrangement of the X-ray detection elements in the channel direction of the X-ray detector 9, and the vertical axis indicates the measurement data value in each X-ray detection element. In this example, the measurement data of the channel P1 indicates a valid value, and a protruding area exists on the left side of the channel P1.

The overhang correction of this embodiment is performed in accordance with the size of the FOV. The size of the FOV is divided into large (L), medium (M), and small (S). If the FOV is large, it is corrected as if the overhang area is large. If the FOV is small, the overhang area is small. And correct it. The correction amount of the measurement data is obtained by linear approximation based on the measurement data of the channel P1. In the case shown in the figure, when the FOV is small, the range of the measurement data is extended to channel S. When the FOV is medium, the range of the measurement data is extended to channel M. When the FOV is large, the range of the measurement data is extended to channel L. Has been corrected.

In the second example of the overhang correction shown in FIG. 12A, the measurement data of the overhang portion is corrected by broken line approximation. The difference between this example and the first example of the overflow correction is whether the measured data is approximated by a straight line or a broken line.
Other parts are almost the same. In the case of this example, since a line diagram is used, it is possible to perform an approximation of a change that is gentler than a straight line approximation. Both can be used properly according to the shape of the subject and the like.

[0080]

As described above, by implementing the present invention, in a multi-slice type X-ray CT apparatus, a FO
According to the size of V, more measurement data can be collected and taken in, and efficient measurement can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire system of a multi-slice X-ray CT apparatus according to the present invention.

FIG. 2 is a diagram schematically illustrating a configuration of a main part of a multi-slice X-ray CT apparatus according to the present invention.

FIG. 3 is a diagram showing an example of a data acquisition range of measurement data in the multi-slice X-ray CT apparatus of the present invention.

FIG. 4 is a view for explaining a first conventional example of control for taking in measurement data in a slice direction.

[0015] FIG. 5 is a second diagram illustrating control of acquisition of measurement data in a slice direction.
The figure for demonstrating the conventional example of FIG.

FIG. 6 is a diagram for explaining a first embodiment of control for taking in measurement data in the slice direction of the multi-slice X-ray CT apparatus of the present invention.

FIG. 7 is a diagram for explaining a second embodiment of the control for taking in measurement data in the slice direction of the multi-slice X-ray CT apparatus of the present invention.

FIG. 8 is a diagram for explaining a third conventional example of control for taking in measurement data in a slice direction.

FIG. 9 is a diagram for explaining a third embodiment of control for taking in measurement data in the slice direction of the multi-slice X-ray CT apparatus of the present invention.

FIG. 10 X-ray CT when the operator determines the size of FOV
6 is a flowchart of an example of a sequence of the device.

FIG. 11 is an example of protruding measurement data.

FIG. 12 is an example of correction of measurement data protruding.

FIG. 13 is a block diagram showing the entire system of a multi-slice X-ray CT apparatus according to a prior art example.

FIG. 14 illustrates a prior art example using a multi-slice X-ray detector having an X-ray detection element array divided into eight in the slice direction.
FIG. 4 is a block diagram when measuring 1.25 mm × 4 slices.

FIG. 15 is a block diagram in a case where measurement of 2.5 mm × 4 slices is performed using the same X-ray detector as in FIG. 14;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 scanner 2 control device 3 image processing device (image processing unit) 5 scanner rotating plate 6 gantry 7 opening 8 X-ray tube 9 X-ray detector (multi-slice X-ray detector) 10 … Detector circuit section 11, 60… X-ray beam 12… X-ray beam collimator 13… Slice direction collimator 14… Beam opening angle collimator (channel direction collimator) 15, 62… X-ray detection element 16… Transmission circuit 21… Keyboard 22, 65 ... Scan condition setting circuit 23 ... Scanner control circuit 24,66 ... Collimator aperture control signal 25,70 ... Detector circuit switch switching control signal (switch control signal) 26 ... Transmission circuit control signal 27 ... Extension correction circuit 28 ... Image reconstruction Circuit 29: Magnetic disk device 30: Image display device 31, 69: Switch circuit 32, 46a, 46b, 46c, 46d: Transmission sorting mechanism 35: Measurement data 36: Image data 37: Scanner system Signal 38: Image processing control signal 40: Detection circuit element 41: Switch element 43, 43a, 43b, 43c, 43d: X-ray detection element group for one channel 44, 44a, 44b, 44c, 44d: Detection for one channel Circuit element group 45, 45a, 45b, 45c, 45d: Switch element group for one channel 48: View angle θ line

Claims (3)

[Claims] An X-ray source, a multi-slice X-ray detector having a plurality of X-ray detection elements arranged in both a channel direction and a slice direction, and a channel direction of an X-ray beam emitted from the X-ray source An X-ray collimator for limiting the width and thickness in the slice direction, a detection circuit for performing preprocessing of measurement data of the X-ray detector, a transmission circuit for transmitting an output of the detection circuit to the image processing apparatus, and a CT circuit based on the measurement data. An image processing apparatus for reconstructing an image, an X-ray source and an X-ray detector are arranged facing each other and mounted, and a scanning mechanism that rotates around a subject and a control device that controls each device are provided. In the multi-slice type X-ray CT apparatus, the detection circuit has the same number or less of detection circuit elements as the number of X-ray detection elements of the X-ray detector, and is provided between the X-ray detector and the detection circuit. Is the output of the X-ray detector. A switch circuit comprising a plurality of switch elements for connecting a force to the detection circuit element, and / or an output from the detection circuit element between the detection circuit and the transmission circuit, and selecting the output from the transmission circuit. A transmission selection mechanism for sending is provided, and the connection by the switch element of the switch circuit or / and the selection of the detection circuit element by the transmission selection mechanism are performed according to the effective visual field to be measured or the size of the subject. Multi-slice type X characterized by
Line CT device. 2. The multi-slice X-ray C according to claim 1.
In the T device, of the measurement data measured by the X-ray detection element of the X-ray detector, the measurement data is connected to the detection circuit element of the detection circuit by the switch element of the switch circuit, and / or selected by the transmission selection mechanism. The multi-slice X-ray C is characterized in that the product of the number of measurement data in the channel direction and the number of measurement data in the slice direction is constant with respect to the measurement data sent to the transmission circuit.
T device. 3. The multi-slice type X according to claim 1 or 2,
In the X-ray CT apparatus, of the measurement data of the X-ray detection element connected by the switch element of the switch circuit and / or the measurement data of the X-ray detection element selected by the transmission selection mechanism, the effective field of view or the field of view for measuring the number of measurement data in the channel direction A multi-slice X-ray CT apparatus, which is changed according to the size of a sample.