JPH02213754A - Ct device for industrial purpose - Google Patents

Abstract

PURPOSE:To obtain tomogram having good quality with simple constitution by integrally moving a radiation source and detecting means in the direction perpendicular to the rotary shaft at every rotation of the sectional plane by a prescribed angle each. CONSTITUTION:The radiations radiated from the radiation source toward the arbitrary sectional plane of an annular specimen are detected by a detector 9 provided near the center of the annulus ring of the specimen. The specimen is rotated at prescribed angle each within the plane inclusive of the sectional plane around the approximate center of the sectional plane as the rotary shaft A moving truck 57 moves the radiation source and the detector 9 in one unit in the direction perpendicular to the rotary shaft at every rotational movement of the sectional plane at this time. The specimen is, therefore, rotated by the prescribed angle each at every execution of one movement, i.e. traversing by a traversing mechanism part 43 and the radiations transmitted through the specimen are detected while the traversing and the rotation of the specimen are alternately executed. The tomogram having the good image quality are thus obtd.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention measures the amount of transmitted tli rays that have passed through the object, and determines the l! The present invention relates to an industrial CT apparatus designed to obtain 1iliifiQ.

(Prior Art) In recent years, various industrial CT apparatuses have been developed that obtain tomographic images of a subject by irradiating the subject with tlI copper wires such as X-rays.

As such a conventional industrial CT apparatus, the one shown in FIG. 8 is known.

The conventional example shown in FIG. 8 is a so-called third generation industrial CTi device that can obtain IiM& only by rotation without performing traverse, and is a sector scan type CTi device having a sector scan mechanism section 101.
It is a T device. This conventional CT apparatus emits fan beam-shaped X-rays in a pulse form from an X1a tube 103, and arranges the X-rays that have passed through the tomographic plane on one side of a tire 105, which is an object to be examined, in an arch shape on an arm 107. multiple detectors 10
9 to detect it. Further, the tire 105 is configured to be rotatable by a rotation mechanism section 111 about a vertical axis passing approximately through the center of the tomographic plane, and a load can be applied by a load mechanism section 113.

(Problems to be Solved by the Invention) As described above, the conventional example shown in FIG. 8 is excellent as a method for scanning a donut-shaped, that is, annular, object, but has the following drawbacks.

For example, when using a high-energy type X-ray tube 103 for emitting high-energy X-rays, it becomes necessary to use energy-type detectors 109 as well.

However, in the third generation CT apparatus, a plurality of detectors 109 are provided, and each detector has a ring-shaped data area 1. In other words, the scanning rotation center (
Since the detector is responsible for data on a concentric circle with respect to the scan center (hereinafter referred to as the scan center), there is a high possibility that ring-shaped artifacts will occur in the image, and there is a strict requirement for uniformity of characteristics between the detectors. Therefore, various corrections such as sensitivity correction and offset correction between detection channels are required, and correction processing for obtaining good image quality is difficult and complicated.

The present invention has been made in view of the above-mentioned problems, and it is possible to obtain a tomographic image of good quality with a simple configuration.
The purpose is to provide a T device.

[Structure of the invention] (Means for solving the problem) Industrial CT provided by the present invention to achieve the above object
The device includes a radiation source that emits fan-beam radiation to an arbitrary tomographic plane of a toroidal object, and a radiation source that is located approximately near the center of rotation of the toroidal object and detects radiation that has passed through the tomographic plane. in a plane including the tomographic plane,
and a rotation means for rotating the tomographic plane by a predetermined angle about the approximate center of the IIi layer plane as a rotation axis, and a direction perpendicular to the rotation axis each time the tomographic plane is rotated by a predetermined angle by the rotation means. The radiation source and the detection means may be moved together by a moving means.

(Function) The present invention detects radiation emitted from a radiation source toward an arbitrary tomographic plane of a toroidal object by a detection means provided near the center of the toroid of the object. Moreover, this object is rotated by the rotation means! It is rotated by a predetermined angle within a plane including the tomographic plane with the approximate center of the Ii1 plane as the rotation axis. At this time, the moving/moving means integrally moves the radiation source and the detecting means in a direction perpendicular to the rotation axis every time the tomographic plane rotates. Therefore, the object is rotated by a predetermined angle each time it is moved, that is, traversed, and while the traverse and rotation of the object are performed alternately, the radiation that has passed through the object is detected and a good result is obtained. We are trying to obtain high-quality cross-sectional images.

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

First, the configuration will be explained with reference to the block diagram in FIG.

The inspection table @1 includes an X-ray tube 3 that continuously emits X-rays, a collimator 5 that shapes the X-rays emitted from the XM tube 3 into a fixed fan beam shape, and A collimator 7 prevents the incidence of X-rays, a detector 9 detects the X-rays that have passed through the subject, and the detection data output from the detector 9 is subjected to processing such as A/D conversion and output as projection data. The data collection unit 11, the mechanical units 13 such as the traverse mechanism unit 43, the shift mechanism unit 47, the rotary mechanism unit 55, and the positioning mechanism unit 63, and a Operation panel 1
5.

Further, the detector 9 is a PHD (Photo Diode).
) By combining, for example, 44 detection blocks constituted by scintillators, it has 44 channels.

The CPU 17 includes an inspection station 1, a console 19, and a control panel 2.
1, and controls the operation of the entire apparatus, and reconstructs a tomographic image of the subject while making various corrections based on the projection data input from the data acquisition section 11.

The console 19 for performing various operations is the photographing unit 2
3. It is connected to the display 25 and the X-ray controller 27, respectively.

The photographing unit 23 is connected to the CPU 17 via the console 19.
A tomographic image displayed on the display 25 is photographed and recorded under control from the controller.

The display 25 displays setting conditions and the like inputted from the operation panel 15, and also displays a tomographic image of the subject reconstructed by the CPU 17.

The control panel 21 includes a mechanism section 13, an operation panel 15, and a CPU 17.
, console 19, and X-ray controller 27, respectively. This pruning machine 21 uses $ from the CPU 17.
The mechanism section 13 and the X-ray controller 27 are controlled based on the 11111 command or the operation commands from the operation panel 15 and the console 19.

The voltage transformer 29 together with the high voltage generator 31 generates high voltage driving power and supplies it to the X-ray tube 3.

Oil cooler 33 is X-ray i13 and high voltage transformer 29
to cool down.

Next, the X-ray tube 3, the detector 9, the mechanism part 13 and its periphery"32
2 device will be explained with reference to the perspective view of FIG.

The X#I tube 3 and the detector 9 are each attached to both ends of the arm 41 and are driven together. The detector 9 has a length L o s and a width WD, and is provided facing the X-ray tube 3 .

Specifically, the X-rays emitted from the X-ray tube 3 are formed into a fan beam shape with a fan angle α by the collimator 5, and this fan angle α is oriented in the traverse direction as shown in the plan view of FIG. 3rd with respect to axis HT perpendicular to FT
It is set at a position offset to the left in the figure. Therefore, the detector 9 is placed at a position offset to the left in FIG. 3 from the axis HT in order to detect the fan beam-shaped X-rays having the fan angle α thus set.

The traverse mechanism section 43 has a pair of rails 45, 45, and by moving the arm 41 in the traverse direction FT, which is the direction along the rails 45, the X-ray tube 3 and the detector 9 are traversed. .

The shift mechanism section 47 has a pair of rails 49 arranged in a direction perpendicular to the traverse direction FT, and by moving the entire traverse mechanism section 43 along the rails 49, the shift mechanism section 47 moves between the X-ray tube 3 and the traverse direction FT. The detector 9 is moved together with the detector 9 in a direction FS perpendicular to the traverse direction FT.

The rotation mechanism section 55 rotates while holding the tire 51, which is the subject, by the clamper 53. At this time, the tire 51 is rotated within a plane including the tomographic plane, with the vertical axis passing through the scan center approximately at the center of the tomographic plane as the rotation axis.

The moving cart 57 is for moving the upright tire 51 to the right, that is, to the scanning position. A pressure mechanism section 59 is provided on the movable cart 57, and a pressure receiving plate 61 is provided at a position facing the pressure mechanism section 59.
In other words, the tire 51 can be pressurized, that is, a load can be applied to the tire 51.

The positioning mechanism section 63 is for positioning the tire 51, and thereby sets the rotation center axis of the tire 51. Specifically, the rotation mechanism section 55
The rotational axis of the tire 51 is set to coincide with the axis of rotation of the tire 51 rotated by.

Next, the operation when obtaining a tomographic image of a normal-sized tire as an object to be examined will be explained with reference to FIGS. 3 and 4.

First, in step S1, the X-ray tube 3 and the tiles 51 are set at scan start positions. That is, the radiation center of the X-ray tube 3 is set at position pa, and the tires 51 are rotated to match the tomographic plane 51a on which the tomographic image is desired and the fan beam plane of the X-rays emitted from the X-ray tube 3. In this way, the tire 51 is held by the clamper 53. At this time, the tire 51 is rotatably held by the rotation mechanism 55 with the position Po, which is the center of the tomographic plane, as the rotation center, that is, as the scan center, and the angle θ (θ -180
−α) can be rotated. Therefore, at the scan start position, the tomographic plane 51a of the tire 51 is located on the straight line H8.

Next, in step S3, the traverse mechanism section 43 is driven to move the X-ray tube 3 and detector 9 together in the traverse direction FT (
L) by a distance of 11La. During this traverse in the traverse direction FT (L), the X-ray tube 3
X-rays formed in the shape of a fan beam with a fan angle α are emitted from the sensor, scan the scan area φR, and obtain an amount of data Da corresponding to the number of detection channels.

Next, in step S5, it is determined whether a prescribed amount of data regarding the tomographic plane 51a has been obtained, and if the prescribed amount of data has not been obtained, the process advances to step S7.

In step S7, the rotation mechanism unit 55 is driven to rotate the tomographic plane 51a by an angle α equal to the fan angle counterclockwise around the scan center PO of the tomographic plane 51a.

Returning from step S7 to step S3, the traverse i side portion 43 is driven to cause the xfs tube 3 and detector 9 to traverse a distance 1a in the opposite direction FT (R) from the previous time. Even when moving in the opposite direction, step 3
Similarly, a fan beam-shaped X-ray with a fan angle α is emitted from the X1il tube 3 to obtain an amount of data □b corresponding to the number of detection channels.

Similarly, after the X-ray tube 3 and the detector 9 are integrally traversed, the tire 51 is sequentially rotated by the angle α to continue collecting data. Therefore, as shown in FIG. 5, each time the tire 51 is rotated by an angle α, the mountain data Da corresponding to the number of detection channels is generated.

Ob, . . . are obtained in sequence.

If the tomographic plane 51a is rotated by the angle θ in step S5, that is, if data has been obtained a prescribed number of times, the process advances to step S9 and the scanning operation is ended.

When the scanning operation described above is completed, for example, the radiation center of the X-ray tube 3 is located at position Pb, and the cross section 51b is located symmetrically to the tomographic plane 51a of the tire 51.
exists on the straight line HP, and the X-ray tube 3 and the tire 51 are closest to each other.

In this way, even when the Xl tube 3 and the tire 51 are close to each other, the configuration is such that the XS beam emitted from the X-ray tube 3 does not interfere with the tire 51.

That is, the direction of the fan beam of XJ) emitted from the X-ray tube 3 and the position of the detector 9 that detects this X-ray are
By deviating by α/2, for example, with respect to the perpendicular line HT drawn from the detector 9 toward the center point pb of radiation of the XrjA tube 3, a degree of leeway is provided in the arrangement of the fan beam and the tire 52. ing.

Next, referring to FIG. 6, the operation when obtaining a tomographic image of a tire having a larger tire width, tire height, etc. will be explained.

First, the scan area φRa becomes wider depending on the shape of the tire 52 that is the object to be inspected.
In order to reliably scan the X-ray tube 3 and the detector 9, it is necessary to set a long distance Lb for traversing the X-ray tube 3 and the detector 9.

In addition, in order to prevent interference between the detector 9 and the tires 52, the shift mechanism 47 is operated to move the X-ray tube 3 and the detector 9 together in the direction FS (D) perpendicular to the traverse direction FT and away from the scan center. move it to In this way, scan start position [Pc and scan end position li! P
d.

As shown in FIG. 6, when the scanning operation is completed, that is, when the X-ray tube 3 and the tire 52 are closest to each other, the center of the X-ray tube 3 moves from the position PO to the position Pd, and the cross section of the tire 52 The surface 52b exists on the straight line HPa. At this time, the direction of the fan beam of X-rays emitted from the X-ray tube 3 and the position of the detector 9 that detects these X-rays are drawn from the detection B9 toward the center point Pd of radiation of the XI tube 3. For example, since it is deviated by α/2, NPd can be set to the right side by the amount of this deviation, and it is possible to provide a margin in the arrangement of the Xva pipe 3 and the tire 52. can.

Next, another embodiment of the present invention will be described with reference to FIG.

This embodiment is characterized in that the fan beam of the X-rays emitted from the X-ray tube 3 is further deviated.

In other words, a straight line H rotated by an arbitrary angle α around 1iP+ with respect to the perpendicular line HT perpendicular to the traverse direction FT.
A fan beam-shaped X-ray is radiated to a region between T2 and a straight line HT3 further rotated by a fan angle α, and a detector 9 is arranged at a position where it can detect this deflected fan beam-shaped xlI. I am trying to set it up.

The embodiment shown in FIG. 7 is configured to further deviate the fan beam-shaped X-rays emitted from the X-ray tube 3, so that the margin of arrangement between the X-ray tube and the subject can be further improved. Can be done. It goes without saying that the deviation angle α1 at this time may be a negative value.

[Effects of the Invention] As described above, according to the present invention, a tomographic plane of an annular object can be detected using a so-called second generation CT device that alternately performs traverse and rotation of the object. Therefore, it is possible to easily obtain a tomographic image of good image quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a block diagram of the embodiment according to the present invention, and FIG. 3 is an explanatory diagram showing the operation of the embodiment shown in FIG. Fig. 4 is a flowchart showing the operation related to scanning, Fig. 5 is an explanatory drawing showing the collected data, Fig. 6 is an explanatory drawing showing the operation when scanning objects with different shapes, Fig. 7 8 is an explanatory view showing another embodiment of the present invention, and FIG. 8 is a perspective view showing a conventional example. 3...xIa tube 9...Detector 43...
Traverse mechanism section 47...Shift mechanism section 55...Rotation mechanism section

Claims (1)

[Scope of Claims] A radiation source that emits fan-beam-like radiation to any cross-sectional plane of a toroidal object; a detection means for detecting the radiation generated by the tomographic plane; a rotating means for rotating the tomographic plane by a predetermined angle within a plane including the tomographic plane and about the approximate center of the tomographic plane as a rotation axis; An industrial CT apparatus comprising: a moving means capable of moving the radiation source and the detection means together in a direction perpendicular to the rotation axis each time the radiation source rotates by a predetermined angle.