JPH0678914A - Radiation ct and photographing data collecting method of radiation ct - Google Patents

Abstract

PURPOSE:To realize a radiation CT capable of obtaining a high quality image, completely eliminating a false image due to PVE or the like produced according to helical scanning and a photographing data collecting method carried out by using the radiation CT. CONSTITUTION:A gantry G is moved to emit a helical fan-like X-ray from a linear X-ray generating source XS parallel to the moving axis of the gantry G. A detector DET rotated around the periphery of a tested body B in a body with the X-ray generating source XS detects an X-ray transmitted through the tested body B and an X-ray not transmitted therethrough to reconfigure an image, and the image is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation CT for continuous high-speed imaging of an object and a method for collecting imaging data of the radiation CT, which can be used for mass examination and the like.

[0002]

2. Description of the Related Art Radiation CT irradiates a subject with radiation in each direction and detects the radiation that has passed through the subject.
It is a device that obtains a tomographic image of a subject by performing image reconstruction calculation from data captured over 0 °. Less than,
As the radiation CT, an X-ray CT will be described. This 360 °
Data is collected over one slice plane.
In normal X-ray CT, movement of the subject in the movement axis direction and imaging / data collection are performed separately. That is, since it is not possible to perform imaging and data acquisition during the movement of the subject in the movement axis direction, the scanning time becomes long, and the tomographic data that can be collected during the subject's respiratory arrest is at most several slice planes. belongs to.

On the other hand, to know the state of a certain organ,
It is necessary to collect 0 to 100 tomographic data, but for this purpose, it is necessary to perform respiratory arrest several to several tens of times. There is a method called helical scan as a method of shortening the imaging time and imaging a large number of slice planes during one breath to improve the throughput.

[0004]

By the way, the movement of the subject in the movement axis direction and the imaging / data acquisition are simultaneously performed with respect to the subject, that is, continuous high-speed scanning is performed to obtain the data at high speed. A helical scan is effective for capturing and collecting images, but this helical scan has the following major problems. That is, in the current helical scan, imaging is performed only from one direction on one cross section. Therefore, since data in all directions for one cross section for image reconstruction is not captured, it is necessary to obtain data in all directions for one cross section by calculation such as interpolation from the cross section in the vicinity thereof. Therefore, the adverse effect of PVE (Partial Volume Effect) is extremely large, and the image quality is extremely inferior to the conventional X-ray CT. If high-speed shooting is attempted, the adverse effect of PVE becomes even greater and the image quality deteriorates significantly. Therefore, both high speed and high image quality are incompatible.

These problems are essentially due to the measurement method of the helical scan, and they are problems that cannot be solved by algorithm improvement such as interpolation processing. The solution to these problems is disclosed in Japanese Patent Application No. 57-11687;
However, this has the following problems. A gantry that reciprocates in the direction of the body axis is required, and the mechanism is very complicated. Therefore, the gantry becomes expensive, the reliability of the gantry or the like is deteriorated, and the gantry becomes unsuitable for high-speed and large-volume scanning.

The present invention has been made in view of the above points, and an object thereof is a radiation CT capable of obtaining a high-quality image in which a false image due to PVE or the like caused by a helical scan is completely eliminated. It is to realize a method for collecting imaging data using this radiation CT.

[0007]

According to the present invention for solving the above problems, a transmission image of a subject by radiation is continuously measured while continuously moving the subject in the direction of a moving axis such as a body axis. In a radiation CT for non-destructively imaging the internal structure of a subject, a table on which the subject is placed and which can be moved at a constant or variable speed in the moving axis direction of the subject, and an imaging cross-section method A gantry capable of changing the direction of the line with respect to the moving axis direction, and irradiating the reconstruction area including the object, which is housed in the gantry, with radiation to determine whether the line is parallel to the moving axis or the imaging section method. A linear radiation source placed on a line segment parallel or nearly parallel to the measurement axis of the measurement system which is parallel to the line, and the ray generation on the surface surrounding the subject around the measurement axis. Placed facing the source and the subject is continuous A detector arranged so as to collect data capable of reconstructing an image similar to the stationary state of the subject despite moving in the movement axis direction. .

A second aspect of the invention is characterized in that the radiation source is a point-shaped radiation source which moves on a cylindrical surface whose axis is the measurement axis in a spiral winding locus. . According to a third aspect of the present invention, a radiation source has at least one linear source radiation source extending in the measurement axis direction, a radiation shield that forms a cylindrical surface with the measurement axis as an axis, and the cylindrical surface. Collimator comprising a vine-wound spiral-shaped first slit provided in the, a radiation shield forming a part of a cylindrical surface having the measuring axis as an axis, and a measuring axis provided on the cylindrical surface. And a second collimator including a second slit parallel to the radiation source.

According to a fourth aspect of the invention, the radiation source generates electrons by thermionic emission, electric field electron emission or the like, and the electrons are focused by an electron lens or the like and magnetically or electrostatically deflected to form a linear target. It is an X-ray generation source that changes the position of collision with the target and collides with a predetermined portion of the target to generate X-rays.

A fifth aspect of the present invention is a radiation generating source for generating fan-shaped radiation on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of a cross section to be measured by the radiation generating source. It is characterized by being.

A sixth aspect of the present invention is a radiation generating source for generating a cone-beam-shaped radiation on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of a cross section to be measured by the radiation generating source. It is characterized by being.

According to a seventh aspect of the invention, the detector has a one-layer structure extending in the measurement axis direction, and the detector is composed of a plurality of detector elements spread one-dimensionally in the cross section to be measured. X
The radiation emitted from S) is detected by a portion of the detector element on or near the plane.

An eighth aspect of the invention is that the detector is a two-dimensional detector having a multi-layer structure in the direction of the measurement axis and having a spread in this direction as well, and is composed of a plurality of detector elements spread two-dimensionally. It is characterized by.

A ninth aspect of the present invention is characterized in that the detector is arranged so as to face the radiation source and rotates integrally with the radiation source. In a tenth aspect of the invention, the detectors are fixedly arranged over the entire circumference so as to surround the subject, and a radiation source that rotates over the entire circumference is arranged between the detector and the subject. It is characterized by that.

An eleventh aspect of the invention is a radiation CT imaging data collecting method for imaging the internal structure of a subject by radiation while continuously moving the subject in the direction of the movement axis. Such as a step of continuously moving one-dimensionally in the direction of the moving axis such as at a constant speed or a variable speed,
With a linear radiation source placed on a line segment parallel or nearly parallel to the measurement axis of the measurement system parallel to the moving axis or parallel to the normal line of the imaging section and the measurement axis as the center Rotating the two-dimensional detector integrally with the radiation source on the surface surrounding the subject around the subject, and with the movement of the subject in the movement axis direction. The step of causing the radiation source to generate fan-shaped radiation on the plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross-section to be measured whose position on the measurement axis is changed And collecting data by detecting the radiation that has passed through the subject or the radiation that has passed through and the radiation that does not pass through the detector on the plane or in the vicinity of the plane, in all directions required for the cross section. Detection of radiation data And, if necessary, performing this imaging and data collection continuously to detect and collect a plurality of slice data, and a step of imaging the internal structure of the subject from the obtained data. It is characterized by consisting of.

In a twelfth aspect of the present invention, the step of rotating the radiation generating source around the subject is a spiral winding in a spiral shape on a cylindrical surface having the measuring axis as the axis of the radiation generating source of the second or third aspect. It is characterized by being in the stage of drawing a trajectory.

A thirteenth aspect of the invention is a cone beam from the radiation source on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction for the portion to be measured of the subject including the cross section. Of radiation in the form of rays, two-dimensional detection of radiation by a detector near the plane and data collection, and radiation corresponding to data in all directions required as the cone beam data. The present invention is characterized by comprising a step of detecting and collecting data, and a step of detecting and collecting a plurality of cone beam data by continuously performing this imaging and data collection, if necessary.

In a fourteenth aspect of the invention, a step of irradiating a fan-shaped radiation from a radiation source on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross section to be measured, Detecting radiation by a plane or a portion of the one-dimensional detector according to the seventh aspect of the present invention in the vicinity of the plane.

A fifteenth aspect of the invention is characterized by including a scan for obtaining data in a plane that is not perpendicular to the moving direction of the subject and a step of collecting data.

A sixteenth aspect of the present invention is to provide a plurality of radiation sources on a plurality of planes corresponding to respective positions on a measurement axis corresponding to required imaging directions with respect to a plurality of cross sections which are not necessarily adjacent to each other. Simultaneously generating fan-shaped or conical radiation from the detector, simultaneously detecting and collecting the radiation with a detector on or in the vicinity of each of the plurality of planes, and for multiple slice sections. And a step of detecting and collecting data in all directions, and a step of detecting and collecting a large number of slice data by continuously performing this imaging and data acquisition, if necessary. Is.

[0021]

Function: The subject moves on a moving axis such as a body axis. A radiation source on a line segment parallel to the moving axis rotates around the subject together with a detector arranged on a straight line including the radiation source or on a cylindrical surface having the moving axis as an axis. . The rotation of the radiation generation source may be a point-shaped radiation generation source that performs a spiral winding motion. The cross section of the object to be measured continuously moves on the moving axis as the object moves, but in the plane corresponding to each position on the moving axis of the moving cross section, the radiation generation on this plane is generated. A fan-shaped X-ray is generated from the source, and the detector on this plane detects the radiation transmitted through the subject and the radiation not transmitted, and collects data. As a result, it is possible to capture an image of an arbitrary cross section or an arbitrary portion of the subject that continuously moves in the movement axis direction such as the body axis in a stationary state and collect data.

The vine-shaped spiral movement may be a movement drawn by a point-like radiation generating source by itself, but may be a movement in which the radiation from the linear radiation-generating source is caused to make a vine-like spiral movement by using a collimator.

The detectors may be arranged on the circumference so as to surround the subject, and in this case, only the radiation source rotates.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an X-ray CT according to an embodiment of the present invention.

In the figure, TBL is a table on which the subject B is placed and can be moved at a constant speed or at a variable speed in the moving axis direction such as the body axis, and G is the moving axis in the direction of the normal line of the imaging cross section. It is a gantry that can be arbitrarily changed with respect to the direction and can rotate the X-ray focal point XS and the detector DET around the measurement axis of the measurement system at a constant speed or a variable speed. The measurement axis of the measurement system is the reconstruction axis RA including the subject of FIG. 2 and the central axis of the cylinder (O in FIG. 2A).
And a measurement axis may coincide with the movement axis such as the body axis, or may be parallel to the normal line of the imaging cross section.

The detector DET is composed of a large number of detector elements which are spread one-dimensionally in a plane perpendicular to the measurement axis direction, whereas the detector DET is also arranged in the measurement axis direction (slice direction). The two-dimensional X-ray detector is arranged in a multi-layered manner on a cylindrical surface having a straight line including the linear X-ray focal point XS or a measurement axis as an axis.

The X-ray focal point XS is a linear X-ray generation source extending in the measurement axis direction, is on a line segment parallel to the measurement axis, and has a detector D.
The ET and the X-ray focal point XS are integrated, and the circumference of the reconstruction area RA including the subject B is rotated around the measurement axis.
This movement is only a rotational movement around the measurement axis, and there is no movement in the measurement axis direction. This rotation can be performed at a constant speed or a variable speed, but when the moving speed of the subject B in the moving axis direction is constant, the rotating speed is constant.

FIG. 2 shows a measurement system composed of an X-ray focal point XS and a detector DET which are arranged across the reconstruction area RA. In the figure, (a) is a cross-sectional view taken along a plane perpendicular to the measurement axis, and (b) is a perspective view of the trajectory drawn by this measurement system as seen from the side. The X-ray focal point XS and the detector DET are provided so as to sandwich the reconstruction area RA, and rotate together around the reconstruction area RA. C is a plan view of the trajectory drawn by the X-ray focal point XS, and O is the center of rotation.

As shown in (b), the X-ray focal point XS is a linear X-ray generation source extending in the measurement axis direction, and the detector DET
Forms a two-dimensional curved surface such as a cylindrical surface whose axis is a straight line including the linear X-ray focal point XS as shown in the figure.

A linear X-ray focus XS is generated as the measuring system rotates.
Has a cylindrical surface with the measurement axis as an axis, and an arbitrary plane perpendicular to the measurement axis that changes the position on the measurement axis along with the movement of the subject B in the movement axis direction and the cylindrical surface. The locus of intersection of the circles is any circle C _i from the circle C ₁ to the circle C _N.

Returning to FIG. 1, XR is an X-ray generation controller XG.
By controlling C, at a predetermined position of the X-ray focal point XS, X
It is a high-voltage generation / X-ray tube control unit that supplies a high voltage so as to generate a line.

The DAS collects and amplifies X-ray data corresponding to a predetermined position detected by the two-dimensional X-ray detector DET,
It is a data collection device that performs AD conversion after integration and sends data to the data processing device DP.

The TGC controls the table TBL to move in the body axis direction at a constant speed or a variable speed, and the table / gantry control device for controlling the posture and movement of the gantry. The SCC communicates with the operator. It controls the operation of the data processing device DP and controls the table / gantry control device TGC and the X-ray generation control device XGC.
Is an operation imaging control device that performs unified control related to tomography such as controlling the operation of.

The data processing device DP is the data collecting device DA.
Various correction processes such as X-ray intensity correction, logarithmic conversion, and X-ray quality hardening correction are performed on the input data from S, and the image reconstruction process is performed on the corrected data to calculate the spatial distribution of the X-ray absorption coefficient. Data processing such as. A large amount of data such as reconstructed image data is sent to the mass storage device AM. The mass storage device AM stores a large amount of data such as image data and data generated in the middle of data processing.

The GDC is an image display device for displaying image data obtained by image reconstruction as an image. The MFC is a photography control device for taking a picture of image data obtained by image reconstruction.

Here, for simplification, the direction of the normal line of the imaging cross section is parallel to the direction of the moving axis of the subject such as the body axis and the measuring axis of the measuring system is as described above unless otherwise specified. Consider the case where it coincides with the axis of movement. Therefore, the axis corresponding to the direction of the normal line of the imaging cross section, the movement axis corresponding to the movement direction of the subject, and the measurement axis of the measurement system are expressed as the same and not distinguished.

The operation of the embodiment configured as described above will be described. The subject B is placed on the table TBL, and if necessary, the table TBL is controlled according to the control operation of the table / gantry control device TGC under the control of the operation / imaging control device SCC.
The height of the gantry G is adjusted, and the inclination of the gantry G is adjusted so as to match the direction of the required cross section.

After that, the operator instructs and inputs various kinds of information regarding the scan by conversational processing between the operation photographing control device SCC and the operator. The table TBL is moved to the scan start position by this input.

When the scan is started, the subject B moves in the direction of the moving axis at a constant speed as the table TBL moves. The gantry G integrally rotates the linear X-ray focal point XS and the two-dimensional X-ray detector DET to rotate around the moving axis at a constant speed. These operations are performed under the control of the operation and photographing control device SCC and the table / gantry control device TGC.

One-slice data, which is the imaging data in each direction of 360 ° on the cross section perpendicular to the moving direction, which is the plane of the subject B to be imaged, is collected as follows. As the subject B moves, one section of the subject B to be measured continuously moves on the moving axis, but the section on the moving axis of the section corresponding to each required imaging direction of the section to be imaged is discrete. A fan-shaped X-ray is emitted from an X-ray focal point XS on this plane on a plane corresponding to each converted position. This is controlled by an X-ray generation control device XGC and a high-voltage generation / X-ray tube control unit XR controlled by the operation and photographing control device SCC.

The X-rays that have passed through the subject B and the X-rays that do not pass are detected by the detector DET on this plane.
The data collection device DAS collects data under the control of the data processing device DP. The obtained data in each direction is completely on one section which is the plane of the subject B.

One slice data on the next one cross section (plane) of the subject B is collected as described above. By continuously performing this, required cross sections of the subject B that continuously moves in the movement axis direction are continuously imaged one after another, and data is collected.

Data processing device DP and mass storage device A
The image of each cross section is reconstructed in parallel with the imaging of each cross section of the subject B performed by the control of M, the data collection, or after the end. The image reconstruction is performed from the slice data of each one section according to a known image reconstruction algorithm that is usually used.

In the above scan, it is possible to perform scan and data acquisition for obtaining plane data that is not perpendicular to the moving direction or three-dimensional data including the plane. FIG. 7 is a diagram showing a relationship between a cross section of image capturing and a moving axis such as a body axis. In the figure, PL ₁ is a plane perpendicular to the movement axis LM, and PL ₂ is a plane not perpendicular to the movement axis LM. Thus, parallel to the normal vector n ₁ of the plane PL ₁ and the moving direction vector n, the normal vector n of the plane PL _2
2 and the direction vector n of the moving axis are not parallel.

The following methods are available for performing imaging / data collection by shifting the direction of the normal line of the imaging section from the moving axis such as the body axis (having an inclination). The measurement axis of the measurement system including the X-ray generation source XS and the detector DET is made parallel to the normal line of the imaging cross section, that is, the measurement axis is displaced from the movement axis, and imaging or data acquisition of a plane or a three-dimensional object is performed. The measuring axis of the measuring system is aligned with the moving axis such as the body axis, and the direction of the slit is tilted from the vertical direction of the moving axis. The imaged cross section or the three-dimensional object including the cross section is made incident and detected by the corresponding detector, and the flat surface or the three-dimensional object is imaged and data is collected. With the gantry G, the direction of the normal line of the imaging cross section is tilted from the direction of the movement axis.

The reconstructed image data is stored in the mass storage device AM, displayed on the graphic display device GDC as required, and photographed by the photography control device MFC. As described above, according to the present embodiment, since the data obtained by photographing are completely on the cross section which is the plane of the subject B, the adverse effects of PVE and the like are reduced and the conventional one plane is used. A high-quality image comparable to the image taken in can be obtained by continuous scanning.

The present invention is not limited to the above embodiment. Another embodiment will be described below.

FIG. 3 is a diagram showing a structural example of a measuring system of another embodiment. In the figure, the same reference numerals are used for the same parts as in FIG. In the figure, XSP _i is a part of the X-ray focal point XS, which is a point-shaped X-ray focal portion, and CB _i is an X-ray focal portion XSP.
cone beam of X-rays emitted from the _i, DETP _i is the detector portion which is part of the detector DET for detecting transmitted X-rays by a cone beam CB _i.

In this measuring system, on the movement axis of the cross section corresponding to each required measurement direction of the center cross section in response to the movement of the center cross section of the subject B including the portion to be measured in the movement axis direction. Discretized positions of the X-ray focal point XS
A conical beam CB _i is generated at an X-ray focal portion XSP _i which is a partial focal point, and two-dimensional detection of X-ray data by the conical beam CB _i is performed by a detector portion DETP _i including a central cross section indicated by a dashed line in the figure. And collect data.

The operation of the X-ray CT using the measuring system of this embodiment is the same as that of the embodiment of FIG. The difference between the cone beam scan in this embodiment and the normal one is that the cone beam data in a completely stationary state including the center cross section of the measurement portion can be collected while continuously moving the measured object in the movement axis direction. is there.

In this case, complete or near-perfect scan data on one plane is always obtained at or near the central cross section. The image reconstruction processing of this portion can be performed at high speed. From the data measured by this method, a three-dimensional image reconstruction of the subject B is possible, and an image having high resolution in all directions can be obtained.

FIG. 4 shows an example of the configuration of the measurement system of another embodiment. In this example, three adjacent cross sections of the subject B are simultaneously imaged and data is collected. In the figure,
The same parts as those in FIG. 3 are designated by the same reference numerals. In the figure,
XSP _i1 , XSP _i2 , and XSP _i3 are X-ray focal points XS, respectively.
, And DTP _i1 , DTP _i2 , and DTP _i3 are one-dimensional parts of the detector DET.

In this measurement system, the section to be measured moves in the direction of the moving axis as the subject B moves in the direction of the moving axis.
Three planes corresponding to each discretized position on the movement axis of three cross sections corresponding to each required imaging direction of the cross section (a plane including XSP _i1 and DTP _i1 , a plane including XSP _i2 and DTP _i2 , and an XSP _i3 And a plane including DTP _i3 ), three X-ray focal points XSP _i1 , XSP _i2 , XSP _i3 on these three planes,
Are irradiated with fan-shaped X-rays, and the detectors DTP _i1 , DTP _i2 , and DTP _i3 on the three planes detect X-rays and collect data.

The operation of the X-ray CT using the measuring system of this embodiment is similar to that of the embodiment of FIG. The imaging and data acquisition method of this embodiment is a unique method, and scanning by this method can be performed at high speed.
The image reconstruction is capable of three-dimensional reconstruction by an extremely simple method, and the resolution in each direction can be enhanced, and the image reconstruction processing is extremely superior to the image reconstruction from the cone beam. It has features such as simple and high-speed processing.

In this example, an example of simultaneous measurement of three adjacent cross sections is shown, but it goes without saying that an apparatus for performing simultaneous measurement of an arbitrary number of adjacent cross sections can be configured. Further, it is of course possible to configure an apparatus that simultaneously measures an arbitrary number of cross sections that are not necessarily adjacent to each other. The arbitrary number of non-adjacent cross-sections are discrete cross-sections, or some of them are adjacent and the other is discontinuous.

Further, another embodiment will be described. The configuration of the measurement system of this example is the same as that of FIG. 2, and the X-ray CT using this measurement system is the same as that of FIG. 1, but the detector DET is slightly longer in the moving axis direction and It is a one-dimensional detector having a shape composed of many detector elements in the vertical direction.

The section to be measured moves in the direction of the movement axis as the subject B moves in the direction of the movement axis, and the sections are discretized on the movement axis of the section corresponding to each required imaging direction of this section. At a position, a fan-shaped X-ray is generated from an X-ray focal point XS on this plane, and a detector DET on this plane is generated.
(Or a part of an adjacent detector DET including the plane) is used to perform detection and data collection. The operation of the X-ray CT using this measurement system is the same as that of the embodiment shown in FIG.

According to this embodiment, the acquisition of the imaging data on a perfect one plane of an arbitrary cross section of the subject B continuously moving in the movement axis direction by using the ordinary one-dimensional detector is continuously performed. It can be carried out.

By using this one-dimensional detector DET and the point-like X-ray focal point XS which performs a vine-wound spiral movement around the axis of movement, the example disclosed in the conventional Japanese Patent Application No. 57-116687 (body axis). The structure of the gantry G can be simpler than that of Siemens, which requires a gantry that reciprocates in the direction, and features such as a highly reliable device and a device capable of high-speed continuous scanning of large amounts of data. Can be a device having

Still another embodiment will be described. Figure 1
In each of the methods and apparatuses shown in the above embodiment and other embodiments shown in to, the X-ray focus XS and the X-ray detector DET.
It is possible to prepare a plurality of pairs of the above and operate them in parallel to collect data by a higher speed scan.

FIG. 5 is a block diagram of a measuring system of still another embodiment. In the figure, (a) is a cross-sectional view taken along a plane perpendicular to the body axis direction in which the subject B moves similar to (a) in FIG. 2, and (b) is a side view of the trajectory drawn by this measurement system. It is the perspective view seen from. The same parts as those in FIG. 2 are designated by the same reference numerals. The detector DET in this embodiment is a one-dimensional array of detectors, which is composed of a large number of detector elements arranged in a cross section, and has one layer in the moving direction of the subject B, that is, in the slice direction. . The X-ray focal point XS is a point-like X-ray generating source, CYL is a cylinder including a circular locus C of the X-ray focal point XS, and LN is a straight line passing through the X-ray focal point XS and perpendicular to the cross section shown in FIG. , On the cylindrical surface of the cylinder CYL.

Each of C ₁ , C _i and C _N is a circle resulting from the intersection of each section with the cylinder CYL. In this embodiment, the subject B is continuously moved in the moving direction such as the body axis. At this time, the straight line LN including the X-ray focal point XS and the detector D
The ET integrally performs measurement while rotating around the subject. With this rotational movement, the X-ray focal point XS is moved so that its locus draws a vine spiral on the cylindrical surface. Detector DE
T performs only rotational movement, but does not perform movement in the moving direction of the subject B.

FIG. 6 shows an example of the X-ray focal point XS that performs a helical motion (vine-wound spiral motion). (A) In the figure, C
MT ₁ is disposed between the subject B and the original X-ray generation source XS, and has a cylindrical collimator made of an X-ray shield having the moving axis as a central axis, and SL ₁ is on the cylindrical surface. It is a slit provided in the shape of a vine.

CMT ₂ is a slit SL ₂ extending in the axial direction.
And is a collimator that rotates around the subject B integrally with the original X-ray generation source XS (simultaneously with the detector DET). The X-ray focus XS (not shown) used in the measurement system composed of the collimators CMT ₁ and CMT ₂ is shown in FIG.
In the shape linearly extended in the axial direction as shown in the embodiment of
It is arranged just outside the slit SL ₂ of the collimator CMT ₂ . This X-ray focal point XS is rotated around the subject B together with the detector DET together with the collimator CMT ₂ . Therefore, X-rays can pass only through the intersection of the slits SL ₁ and SL ₂ .

The collimator CMT ₁ may be replaced with a collimator CMT ₃ having slits SL ₃ arranged in a spiral shape as a set of a plurality of small slits on a cylindrical surface as shown in FIG. good.

Since the position of the measurement cross section of the subject B is changed by continuously moving in the moving direction, the irradiation and detection of the X-ray in each discretized direction is the measurement of the subject B. The subject B is irradiated with fan-shaped X-rays from the X-ray focal point XS on the plane including the circle C _i corresponding to the passage position of the cross section, and the detector DET is the portion on the plane irradiated with the X-rays or the portion thereof. X-ray detection is performed in the vicinity of the plane including the plane.

X-ray CT shown in FIG. 1 using the above measurement system
In, the scan and data collection are performed as follows. The subject B is placed on the table TBL and continuously moved in one direction such as the body axis direction.

During the acquisition of imaging data, the straight line LN including at least the X-ray focal point XS and the detector DET are integrally rotated around the reconstruction area RA. During this time, fan-shaped X-rays are emitted from the X-ray focal point XS on the measurement cross section of the subject B in each direction, and the detector DET detects the X-rays. The detected data is processed to make a data acquisition, which is done in all directions required.

By these operations, the collected data is converted into all the data on one complete plane of the subject B (for example, 360 degrees corresponding to one slice on one plane) despite the continuous movement of the subject B. Data in each direction, etc.).

Deformation of Detector The spread of each layer of the two-dimensional detector DET in the slice direction may be linearly thin in principle, but may be thick corresponding to the spread of the fan beam. The number of layers in the moving axis direction of the two-dimensional detector may be equal to, more than or less than the number of one cross section in the imaging direction, that is, the number of views. The section to be measured moves in the direction of the movement axis as the subject B moves in the direction of the movement axis, but each discretized position on the movement axis of the section corresponding to each required imaging direction of the section. X by the one-layer detector DET on each plane or a plurality of adjacent-layer detectors DET including the plane.
Detect lines and collect data.

The detector DET is a two-dimensional or one-dimensional detector (so-called S) which is fixedly arranged on the entire surface of a quadratic curved surface such as a cylindrical surface having the measuring axis of the measuring system as an axis, surrounding the subject B. -R (Stationary-Rotate) system).

The types of the detector DET include a scintillator, a photodiode or a photomultiplier tube, various semiconductor detectors,
Various things such as an ionization chamber detector such as X _e , a proportional counter, an X-ray imaging tube can be used.

Deformation of X-ray source As an X-ray source, a linearly extended X-ray focal point XS that can rotate around the moving axis together with the detector DET is used. The X-ray focal point XS may be a point-like X-ray focal point XS that performs a spiral movement on a cylindrical surface.

As such an X-ray generation source, electrons are generated by thermoelectron radiation, electric field electron radiation, or the like, which are converged by an electron lens or the like and magnetically or electrostatically deflected to form a linear X-ray. It is possible to use a system in which the position of collision with the X-ray target is changed and the X-ray is generated by colliding with a predetermined portion of the target. In this example and the following examples, vacuum generating means such as a vacuum container and a vacuum pump, a cooling device, etc. are omitted.

As another example of the X-ray source, already,
Some use the collimator described with reference to FIG. This
Collimator CMT₁Is usually fixed, but the subject
Moving speed V of the cross section of B_aCM corresponding to
T₂And the original X-ray focus XS and the detector DET are moved as a unit.
For the rotation speed ω rotated around the axis of motion, the subject B
The moving speed of n times (n is an integer), collimator C
MT₂The rotation speed ω of the collimator CMT remains unchanged.₁
At a rotational speed of (n-1) ω ₂And the opposite
It can be configured to rotate in the direction. Again
When the moving speed of the body B is 1 / n, the collimator CMT₂
The rotation speed ω of the collimator CMT remains unchanged.₁To
Collimator CMT at a rotation speed of {(n-1) / n} ω₂
It can be configured to rotate in the same direction as.
The X-ray generation may be performed in a pulsed manner, or
A method of continuously generating may be used.

Modification of measurement system (a) A structure in which a filter or collimator is inserted between the X-ray focal point XS and the subject B. (B) A structure in which a collimator is inserted between the subject B and the detector DET. (C) In the combination of collimators shown in FIG. 6,
The collimator CMT ₂ is not always necessary. The shape of the collimator CMT ₂ may be a flat surface instead of a part of the cylindrical surface. (D) Movement speed of the subject B in the movement axis direction, X-ray focus X
The rotation speed at which the S, the X-ray detector DET, and the like rotate integrally may be constant speed or variable speed. (E) In relation to the moving speed of the subject B in the moving axis direction, to be precise, when the subject B moves at a constant velocity, the first cross section passes the distance between two adjacent cross sections of the subject B to be imaged. After that, the speed V _a (mm / s) corresponding to the value obtained by dividing the time until the passage of the next cross section and the rotation speed for rotating the X-ray focal point XS and the detector DET around the moving axis are integrated. ω (rad /
The relationship with s) is that the length of the detector DET in the moving axis direction is d.
Then, it is selected so as to satisfy the relationship of d / V _a ≧ 2π / ω.

Modification of device (a) Coupling of device A device in which the X-ray generation control device XGC and the high-voltage generation / X-ray tube control unit XR are integrated. (B) Separation of device A device in which the gantry G is separated into a gantry in a narrow sense, a gantry rotation control mechanism, and the like. (C) Of course, the photographing device MFC can be omitted.

In the above description, CT is used as the X-ray and the imaging data acquisition method thereof is described, but many parts can be applied as other radiation instead of the X-ray.

[0079]

EFFECTS OF THE INVENTION It is possible to obtain a high-quality image in which false images due to PVE or the like, which is a current big problem based on helical scanning, are completely reduced. That is, a high-quality image comparable to (matching with) the conventional image captured on one plane can be obtained by continuous scanning.

Even if the image is taken at high speed, an image of very good quality can be obtained without being affected by PVE or the like.
It is possible to achieve both high speed shooting and high image quality.

By photographing data in each direction with a full-scale cone beam, full-scale three-dimensional imaging by the original method becomes possible. Further, it is possible to easily realize an X-ray CT capable of simultaneously imaging a plurality of cross sections at high speed.
That is, image reconstruction is very simple and very fast compared to the conventional cone beam method.

Compared with the conventional device, the structure of the gantry can be simplified, and the device can be a highly reliable device, a device capable of high-speed continuous scanning of a large amount of data, and the like.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of a configuration of a measurement system including an X-ray focus and a detector.

FIG. 3 is a diagram showing a configuration example of a measurement system according to another embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a measurement system according to still another embodiment of the present invention.

FIG. 5 is a diagram showing a configuration example of a measurement system according to still another embodiment of the present invention.

FIG. 6 is a diagram of a configuration example of a collimator for creating an X-ray focus that performs a helical motion.

FIG. 7 is a diagram showing a relationship between a cross section of image capturing and a moving axis such as a body axis.

[Explanation of symbols]

B Subject CMT ₁ and CMT ₂ Collimator DET Detector G Gantry RA Reconstruction area TBL table XS X-ray source

[Procedure amendment]

[Submission date] October 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0064

[Correction method] Change

[Correction content]

CMT ₂ is a slit SL extending in the axial direction
Has a _2, a collimator is rotated about the subject B together with the original X-ray source XS (simultaneously detector DET). In this collimator CMT _1, used in the measurement system consists of CMT ₂ X-ray focal point XS (not shown) extending linearly in the axial direction as shown in the embodiment of FIG. 2 shape, collimator CMT ₂ Is located immediately outside the slit SL ₂ . The X-ray focal point XS is integrated with the detector DET and is rotated around the subject B together with the collimator CMT2. Therefore, X-rays can pass only through the intersection of the slits SL ₁ and SL ₂ . Incident (irradiation) on the subject due to the shape of these collimator slits
The shape of the X-ray to be generated can be set to an arbitrary shape.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0076

[Correction method] Change

[Correction content]

Modification of measurement system (a) A structure in which a filter or a collimator is inserted between the X-ray focal point XS and the subject B. (B) A structure in which a collimator is inserted between the subject B and the detector DET. (C) In the combination of collimators shown in FIG. 6,
The collimator CMT ₂ is not always necessary. The shape of the collimator CMT ₂ may be a flat surface instead of a part of the cylindrical surface. Further, the collimator CMT ₂ may be composed of a plurality of discrete small slits. (D) Movement speed of the subject B in the movement axis direction, X-ray focus X
The rotation speed at which the S, the X-ray detector DET, and the like rotate integrally may be constant speed or variable speed. (E) In relation to the moving speed of the subject B in the moving axis direction, to be precise, when the subject B moves at a constant velocity, the first cross section passes the distance between two adjacent cross sections of the subject B to be imaged. After that, the speed V _a (mm / s) corresponding to the value obtained by dividing the time until the passage of the next cross section and the rotation speed for rotating the X-ray focal point XS and the detector DET around the moving axis are integrated. ω (rad /
The relationship with s) is that the length of the detector DET in the moving axis direction is d.
Then, it is selected so as to satisfy the relationship of d / V _a ≧ 2π / ω.

Claims (16)

[Claims] 1. A transmission image of a subject by radiation is continuously measured while continuously moving the subject in the direction of a movement axis such as a body axis to nondestructively image the internal structure of the subject. In radiation CT to be performed, a table (TB) on which a subject (B) is placed and which can be moved at a constant or variable speed in the movement axis direction of the subject (B).
L), a gantry (G) capable of changing the direction of the normal line of the imaging cross section with respect to the movement axis direction, and a reconstruction area (RA) housed in the gantry (G) and including the subject (B). ) Is irradiated with radiation, and linear radiation generation is placed on a line segment that is parallel or nearly parallel to the measurement axis of the measurement system that is parallel to the movement axis or parallel to the normal line of the imaging cross section. A radiation source (XS) and a radiation source (XS) arranged on a surface surrounding the object (B) centering around the measurement axis, and the object (B) continuously moves along the axis of movement. Detector (D) arranged to perform data acquisition capable of reconstructing an image similar to the static state of the subject (B) despite moving in the direction.
ET) and radiation CT. 2. The radiation source (XS) is a point-shaped radiation source that moves in a vine-shaped spiral locus on a cylindrical surface whose axis is the measurement axis. Radiation CT described. 3. The radiation source (XS) comprises at least one linear source radiation source extending in the measurement axis direction,
A first collimator (CMT ₁ ) including a radiation shield which forms a cylindrical surface having the measurement axis as an axis and a vine-wound spiral first slit (SL ₁ ) provided on the cylindrical surface.
And a second collimator (C) including a radiation shield forming a part of a cylindrical surface having the measurement axis as an axis and a second slit (SL ₂ ) provided on the cylindrical surface and parallel to the measurement axis.
Radiation CT according to claim 1, characterized in that it is a radiation source (XS) consisting of MT ₂ ). 4. The radiation source (XS) generates electrons by thermionic emission, electric field electron emission or the like, focuses the electrons by an electron lens or the like, and magnetically or electrostatically deflects the linear target. 4. The radiation C according to claim 1, wherein the radiation C is an X-ray generation source that changes the position of collision with the target and collides with a predetermined portion of the target to generate X-rays.
T. 5. The radiation source (XS) is a radiation source that generates fan-shaped radiation on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross section to be measured ( XS), the radiation CT according to any one of claims 1 to 4. 6. The radiation source (XS) is a radiation source which generates a cone-beam-shaped radiation on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross section to be measured. The radiation CT according to any one of claims 1 to 4, wherein 7. The detector (DET) has a one-layer structure extending in the measurement axis direction, and is composed of a plurality of detector elements spread one-dimensionally in the cross section to be measured, and a radiation source ( X
Radiation C according to any one of claims 1 to 5, characterized in that the radiation emitted from S) is detected by a part of the detector element on or near the plane.
T. 8. A two-dimensional detector (DET) comprising a plurality of detector elements which are multi-layered in the measurement axis direction and also have a spread in this direction and which are spread two-dimensionally.
The radiation CT according to any one of claims 1 to 6, wherein 9. The detector (DET) is a radiation source (X
Radiation CT according to any one of claims 1 to 8, characterized in that it is a detector which is arranged opposite to S) and rotates integrally with the radiation source (XS). 10. A detector (DET) is fixedly arranged over the entire circumference so as to surround the subject (B), and the entire distance between the detector (DET) and the subject (B). Radiation C according to any one of claims 1 to 8, characterized in that a radiation generating source (XS) rotating around the circumference is arranged.
T. 11. A method for collecting imaging data of radiation CT for imaging the internal structure of a subject (B) by radiation while continuously moving the subject (B) in the direction of a moving axis, the method comprising: B) moving one-dimensionally continuously at a constant speed or a variable speed in the direction of a moving axis such as a body axis, and a measuring system parallel to the moving axis or parallel to a normal line of an imaging cross section. A linear radiation generation source (XS) placed on a line segment parallel or nearly parallel to the measurement axis and the radiation generation source (XS) on a surface surrounding the subject about the measurement axis.
Rotating a two-dimensional detector (DET), which is arranged to face the object, around the subject (B) as a unit, and on the measurement axis along with the movement of the subject (B) in the movement axis direction. A fan-shaped radiation is generated from the radiation generation source (XS) on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross-section to be measured whose position is changed. And, the detector (DET) on the plane or in the vicinity of the plane detects radiation that has passed through the subject (B) or radiation that has not passed and data that does not pass, and data collection is performed.
Detecting and collecting radiation data in all directions required for the cross section, and if necessary, performing this imaging and data acquisition continuously to perform detection and acquisition of multiple slice data, And a step of imaging the internal structure of the subject (B) from the obtained data.
How to collect shooting data. 12. The radiation source (XS) is the subject (B).
The step of causing the radiation source (XS) according to claim 2 or 3 to rotate around is a step of drawing a vine-shaped spiral locus on a cylindrical surface whose axis is the measurement axis. Item 11. A method for collecting radiographic CT imaging data according to Item 11. 13. The radiation source (XS) on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction with respect to a portion to be measured of the subject (B) including the cross section.
Irradiating a cone-beam shaped radiation from the above, two-dimensionally detecting the radiation by a detector (DET) near the plane, and collecting data, and all directions required for the cone beam data. And a step of detecting and collecting radiation data corresponding to the above data, and a step of detecting and collecting a plurality of cone beam data by continuously performing the imaging and data collection, if necessary. Radiation C according to item 11 or 12
Method of collecting T imaging data. 14. Irradiating fan-shaped radiation from a radiation source (XS) on each plane corresponding to each position on the measurement axis corresponding to each required imaging direction of the cross section to be measured, said plane Or a step of detecting radiation by a portion of the one-dimensional detector (DET) according to claim 7 in the vicinity of the plane, the method for collecting imaging data of radiation CT according to claim 11 or 12. 15. The method according to claim 11, further comprising a step of performing a scan for acquiring data in a plane that is not perpendicular to a moving direction of the subject (B) and a step of collecting data.
14. The radiation CT imaging data collection method according to any one of 14. 16. From a plurality of radiation sources (XS) on a plurality of planes corresponding to respective positions on a measurement axis corresponding to required imaging directions, for a plurality of cross sections which are not necessarily adjacent to each other to be measured. Simultaneously generating fan-shaped or conical radiation, and a detector (DE) on or near each of the plurality of planes.
The step of simultaneously detecting and collecting radiation by T), the step of detecting and collecting data in all directions required for a plurality of slice sections, and if necessary, this imaging and data acquisition are performed continuously. 16. The method of collecting radiation CT imaging data according to claim 11, further comprising: detecting and collecting a large amount of slice data.