JP2008145327A - Additional type x-ray ct scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively form an X-ray CT scanner by adding a scan mechanism to a coventional X-ray fluoroscope. <P>SOLUTION: The additional-type scan mechanism is mounted on an examining table of the X-ray fluoroscope while an inspected body is attached to a rotary stage. The additional-type rotary stage, a tool for measuring geometric positional relation among an X-ray tube, an X-ray detector, and the rotary stage, and measurement software are provided. The X-ray CT scanner can be easily formed while it can be removed if unnecessary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an X-ray CT tomographic imaging apparatus.

X-ray CT apparatuses have been put to practical use for medical and industrial purposes, and are widely used in industrial applications as non-destructive inspection and measurement apparatuses having high resolution. Further, a fluoroscopic image apparatus using X-rays has been put into practical use as an apparatus that can easily and non-destructively observe an object for medical and industrial purposes.

However, the industrial X-ray CT apparatus is more expensive than the X-ray fluoroscopic image apparatus, and its practicality is evaluated in comparison with the number of X-ray fluoroscopic image apparatuses spread. It was limited to large companies and research institutes.

The main components of the X-ray CT system consist of an X-ray tube, an X-ray detector, a rotation / movement stage for imaging, and a computer that performs image acquisition and processing, but the X-ray tube / X-ray detector / rotation / movement It is necessary to strictly adjust the geometric positional relationship of the stage.

The X-ray fluoroscopy device consists of an X-ray tube, an X-ray detector, and a moving stage for determining the inspection object imaging position. If a rotary stage and a computer are added as components constituting the X-ray CT tomography device, All major parts will be aligned.

The problem to be solved is that the additional scanning mechanism and computer of the present invention are added as parts to the existing X-ray fluoroscopy device, and the geometric positions of the additional scanning mechanism, the X-ray tube, and the X-ray detector are automatically set. An X-ray CT tomographic imaging apparatus is realized at low cost by making it possible to configure an X-ray CT apparatus by adding jigs and measurement software for measurement.

The present invention includes a computer-controlled additional scanning mechanism including a rotation mechanism, a position measurement jig, position measurement software, and a computer.

By using the present invention, it is possible to obtain a three-dimensional tomographic image by using the existing X-ray fluoroscope and adding the additional scanning mechanism of the present invention as necessary.

A special measurement jig is prepared for the geometric positional relationship of the X-ray tube, X-ray detector, and rotary stage. In combination with measurement software, CT tomographic images can be obtained without strict position adjustment of the additional scanning mechanism. To be able to get.

FIG. 1 shows an additional type scanning mechanism according to an embodiment of the present invention. A scanning mechanism including a rotation stage controlled by a computer is held by a support mechanism. In this embodiment, the rotary stage is mounted vertically, the X-ray tube and the X-ray detector are positioned vertically, and the X-ray is radiated perpendicularly to the inspection object. An inspection object for obtaining a tomographic image is fixed to the rotary stage using a chuck or the like attached to the rotary stage. The support mechanism has a positioning pin for fixing the jig shown in FIG.

Fig. 2 shows the X-ray tube, X-ray detector, and jig used to measure the geometric positional relationship between the rotary stage of the add-on scanning mechanism. Using software, the geometric positional relationship of the X-ray tube, X-ray detector, and rotary stage is measured. The jig is composed of a pipe made of a light and strong material such as plastic that transmits X-rays well, and a sphere made of tungsten, iron, or the like that does not easily transmit X-rays. The spheres are fixed to the pipe at a known three-dimensional position, for example, at equal intervals.

FIG. 3 shows a jig that is attached to an additional type scanning mechanism. Patterns 1 and 2 are located on a plate at known intervals. Holes are drilled in a known position, for example, pattern 1 and pattern 2 at a regular interval in a plate made of a metal that is difficult to transmit X-rays by a process such as etching. Conversely, patterns 1 and 2 that are difficult to transmit through a material such as a plastic plate that is easily transmitted may be generated by etching. Pattern 2 is a different pattern from pattern 1 so that the plate center can be measured. Pattern 1 is asymmetric on the plate so that the positional relationship of the plate can be measured. The pattern shape may be any shape, but the pattern is such that the plate center and the plate positional relationship can be measured.

1 is mounted on the examination table of the fluoroscopic apparatus. The inspection table is made of a strong plate that easily transmits X-rays. In order to prevent the rotating stage from moving easily and to damage the inspection table, a gel-like plate is attached to the lower portion of the support mechanism of the additional scanning shown in FIG.

The computer of the present invention includes a servo control board for controlling the rotary stage and an interphase board for receiving an X-ray transmission signal from the X-ray detector.

1 After the additional scanning mechanism is mounted on the examination table, an X-ray detector signal is connected to an X-ray detector interface included in the computer of the present invention.

The inspection body is attached to the rotary stage, the inspection stage is moved while viewing the X-ray fluoroscopic image, and the rotary stage is moved to a position where the inspection body fluoroscopic image is appropriately obtained.

The inspection object is removed, and the jig shown in FIG. 3 is attached to the positioning pin prepared in the additional scanning mechanism rotary stage support mechanism, and after data collection, the jig shown in FIG. 2 is attached to the rotary stage and data is collected. The geometric positional relationship with the tube and X-ray detector is measured.

Once the geometric positional relationship is measured, X-ray tomographic images of various inspection objects can be taken as long as the position of the additional scanning mechanism does not change.

The embodiment of FIG. 4 is an embodiment for adding to an X-ray fluoroscopy apparatus in which an X-ray tube and an X-ray detector are horizontally mounted, and the rotary stage is mounted on an inspection table installed horizontally, The rotating stage surface is horizontal.

The embodiment of FIG. 5 includes a rotary stage and a vertical stage in the additional scanning mechanism, and the tomographic image capturing position can be freely set by a computer.

FIG. 6 is an example of an algorithm that corrects the detector position using the jig of FIG.

When the correction data is collected, the jig shown in FIG. 3 is attached to a positioning pin of the additional scanning mechanism and measures projection data. From the projection data, each pattern position is measured, and a two-dimensional polynomial indicating the relationship between the known position of each pattern and each detected pattern position is obtained. From this polynomial, correction calculation is performed so that each detected pattern is in its original position.

FIG. 7 shows an algorithm for calculating the positional relationship between the rotation stage center, the scan reference plane, the rotation stage, the X-ray tube, and the X-ray detector using the jig shown in FIG.

FIG. 2 A jig is attached to a rotary stage, and projection data is obtained at various angles while rotating the rotary stage. The ball position and the ball diameter are measured with projection data at each angle. The rotation stage position and the trajectory of each ball center are obtained, and an elliptic function indicating the trajectory is obtained. The center and minor axis of the elliptic function are obtained, and the position where the minor axis becomes 0 is defined as the scan reference plane. The ball diameter on the scan reference plane is calculated according to the rotational position of the rotary stage, and the positional relationship between the rotary stage center, the X-ray tube, and the X-ray detector is calculated from the maximum and minimum values. Find the center of the rotating stage from the center of the ball trajectory.

By adding to an existing X-ray fluoroscopy apparatus, an X-ray CT tomographic imaging apparatus can be configured easily, so that three-dimensional measurement and inspection can be performed non-destructively at low cost. Since it can be easily attached and detached, it can be used as an existing X-ray fluoroscopic apparatus when an X-ray tomographic image is not required.

This is an additional scanning mechanism that is added to an X-ray fluoroscope having an X-ray tube and an X-ray detector vertically. (Example 1) It is a jig that measures the geometric positional relationship between an X-ray tube, an X-ray detector, and a rotary stage. It is a jig that measures the geometric positional relationship between an X-ray tube, an X-ray detector, and a rotary stage. This is an additional scanning mechanism that is added to an X-ray fluoroscope having an X-ray tube and an X-ray detector horizontally. (Example 2) This is an additional scanning mechanism that can set a scanning position to be added to an X-ray fluoroscope having an X-ray tube and an X-ray detector horizontally. (Example 3) Fig. 3 Algorithm for correcting the detector position using a jig Fig. 2 Algorithm for measuring the positional relationship between the rotation stage center, scan plane, X-ray tube, rotation stage center, and X-ray detector using a jig

Explanation of symbols

1 Rotating stage 2 Ball 3 Support pipe 4 Pattern 1
5 Pattern 2 (for plate center detection)
6 Positioning pin hole 7 Horizontal mounting support mechanism 8 Jig mounting foot 9 Scan position selection mechanism

Claims (3)

Addition-type scanning mechanism that can capture X-ray CT tomographic images by adding to existing X-ray fluoroscopy devices Jig for measuring the geometric positional relationship between the additional scanning mechanism and the X-ray tube and X-ray detector of the existing X-ray fluoroscope Software that measures the geometric position using a jig

Images