JP2000193751A - Radiation image-pickup system arrangement confirmation method and arrangement confirmation tool used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily confirm that the flux of radiation is perpendicular to the surface of a detector. SOLUTION: A tool 10 with two different patterns 20 and 30 at both the end faces 12 and 14 is arranged along an axial line for connecting a radiation source 2 to a detector 6. When the end surface 14 of the tool 10 is arranged in parallel with a surface 8 of the detector 6, the projection image of the patterns 20 and 30 is projected onto the detector 6 while being misaligned when the detector 6 inclines to the radiation source 2. The position of the detector 6 or radiation source 2 is adjusted for allowing the centers of two projection images to coincide. When a center 24 coincides with a center 34, it is confirmed that the detector 6 orthogonally crosses the flux of radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation imaging system confirmation method and an arrangement confirmation jig used for the method, and more particularly to radiation imaging for making a detector surface perpendicular to a flux of radiation emitted from a radiation source. How to check the system,
And a placement confirmation jig used for the same.

[0002]

2. Description of the Related Art When acquiring three-dimensional radiation image data on a subject, radiation transmission information on the subject from multiple directions is obtained using a pair of opposed radiation sources and detectors.
Reconstructing three-dimensional information from the obtained image is performed. At this time, the relationship between the radiation source and the detector is set such that the center line of the radiation flux is perpendicularly incident on the detector.
However, the relationship between these detectors and the radiation source can be fixed if the device is dedicated to three-dimensional imaging,
In other cases, it is necessary to reset the positional relationship between the radiation source and the detector each time three-dimensional imaging is performed. Conventionally, in such a case, the positional relationship between the detector and the radiation source has been set by measurement using a measure or the like. However, such a method is not only time-consuming, but also it is difficult to set the vertical relationship with high accuracy.

[0003]

However, in these methods, it was very difficult to confirm that the angle of incidence on the detector was exactly a right angle due to invisible X-rays. In addition, there is a problem in accuracy of photographing and work efficiency due to complexity of work.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a radiation imaging system arrangement confirmation method capable of accurately and easily confirming the positional relationship between a detector and a radiation source. I do.

Another object of the present invention is to provide an arrangement confirming jig used in a radiation imaging system arrangement confirming method capable of accurately and easily confirming a positional relationship between a detector and a radiation source. is there.

[0006]

According to the present invention, there is provided a method for confirming the arrangement of a radiation imaging system, comprising the steps of: positioning a detector vertically with respect to X-rays emitted from a radiation source; It is characterized in that one set of patterns is used. These patterns are arranged coaxially and spaced apart parallel to one another. Then, one of the patterns is aligned with a predetermined position on the surface of the detector for detecting radiation, and is arranged in parallel with the surface. Thereafter, radiation is irradiated from a radiation source, pattern information is recorded on a radiation information recording medium, and the centers of the respective patterns of the projected images of a set of overlapping patterns on the detector coincide with each other from the obtained image. Make sure you do. Thereby, it can be confirmed that the beam from the radiation source is perpendicularly incident on a predetermined position on the surface of the detector. Preferably, the predetermined position is a center point on the surface of the detector.

Further, the arrangement confirmation jig used in the arrangement confirmation method of the radiation imaging system according to the present invention has a set of planar shapes each having a center formed by a radiopaque material. Are provided coaxially and spaced apart and parallel to each other. The jig can be arranged so that one of the patterns is parallel to the surface of a detector for detecting radiation.

It is desirable that the two patterns have different shapes so that the deviation of the patterns can be easily determined.

In particular, one of the two patterns may be a plurality of concentric circular patterns, and the other may be a plurality of concentric regular polygons, for example, a square pattern so that the two patterns can be distinguished. desirable.

[0010] The support member of the pattern may be of any shape as long as the two patterns are formed in parallel and coaxial, such as opposed surfaces such as a cylinder, a square, a truncated cone, and a truncated pyramid.

The supporting member of the pattern is desirably formed of a resin material such as plastics, or a radiation transmitting material such as a tree which easily transmits radiation.

[0012] The support member of the pattern may be provided with a spacer member that can be attached to the surface of the detector while being spaced apart.

Here, the non-radiation-transmitting substance also includes the same material as the radiation-transmitting substance whose thickness is increased so as to make it difficult to transmit radiation relatively to the transmission member.

The term "coaxial" means that a straight line orthogonal to two plane shapes passes through the centers of both shapes.

[0015]

According to the radiation imaging system arrangement confirming method of the present invention, a pattern formed of a radiopaque material is projected on a detector. Since the two patterns are coaxially arranged on an axis perpendicular to the surface of the detector, if the radiation is incident at right angles to the detector, the two patterns will be perfectly centered and overlap. Become. This indicates that the detector is correctly oriented at right angles to the radiation flux. On the other hand, if the angle between the ray flux and the detector is deviated from the vertical, the two patterns are projected onto the surface of the detector in a misaligned state because the ray flux is incident obliquely with respect to the detector. . As a result, a position shift can be confirmed. In order to correct this misalignment, the detector and the radiation source are arranged to adjust the positional relationship between the detector and the radiation source so that the centers of the two patterns coincide with each other. it can. Since this operation is performed while viewing the projected images of the two patterns, the adjustment can be performed accurately and efficiently.

When the two patterns have different shapes, it is possible to easily identify the difference between the two patterns, so that it is easy to know in which direction the detector is tilted and to easily correct the position. In a short time.

Further, the arrangement confirming jig used in the arrangement confirming method of the radiation imaging system according to the present invention has a set of planar patterns each having a center formed by a radiopaque material. And the jig can be arranged so that one of the patterns is parallel to the surface of the detector that detects radiation. Is arranged on the detector and the pattern is recorded as radiation image information, so that it can be easily confirmed whether or not the detector is oriented at right angles to the ray bundle due to a positional shift between the two patterns.

When each of the two patterns has a different shape, the positional deviation between the two patterns can be more easily grasped, so that it is easy to determine whether or not the detector is oriented at right angles to the ray bundle. In the case of further inclination, the relative positions can be easily corrected by matching the centers of the two patterns.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing an outline of a method for confirming the arrangement of a radiation imaging system according to an embodiment of the present invention. FIG.
, X-rays (radiation) 4 emitted from the radiation source 2
Reaches the surface 8 of the detector 6. Usually, a subject (not shown) such as a living body is arranged between the radiation source 2 and the detector 6, and the X-ray 4 (transmitted ray) transmitted through the subject is projected on the detector 6 as a projection image. . In the case where a plurality of projection images are obtained while rotating around the subject and three-dimensional volume data is reconstructed using the projection images, the detector 6 is set at a right angle to the flux of the X-rays 4 emitted from the radiation source 2. It is necessary to turn to.

FIG. 1 shows an arrangement confirmation jig (hereinafter simply referred to as a jig) 10 for positioning the detector 6 as an example. The jig 10 has an elongated box (support member) 11 formed of a resin such as wood or plastics, which easily transmits radiation. This jig 10
Various shapes such as a cylindrical shape, a prism shape, a truncated cone shape, and a truncated pyramid shape are conceivable. However, it is necessary to have rigidity that does not easily deform. The jig 10 is shown in a see-through state for easy explanation. A plurality of concentric circular patterns 30 are formed on one end face 14 of the jig 10, and a plurality of concentric square patterns 20 are formed on the other end face 12 on the opposite side. These patterns 20 and 30 are formed of a metal that does not transmit radiation, such as lead and copper. For example, it is formed by a thin metal wire such as a conductive trace formed on a printed circuit board used for an electric component.

Since the end faces 12 and 14 of the jig 10 are formed in parallel with each other, the pattern 2
0 and 30 are also flat plate-shaped patterns parallel to each other. Each of the patterns 20, 30 is a cross-shaped line 22, 32, which is orthogonal.
And their intersections are the centers 24, 34 of the respective patterns 20, 30. Centers 24 and 34 are end faces 12 and 14
The jig 10 is located on the center line 16 of the jig 10 orthogonal to. That is, 2
The two patterns 20, 30 are coaxially spaced apart from each other.

Next, the jig 10 is arranged so that the longitudinal direction of the jig is in a straight line connecting the radiation source 2 and the detector 6.
At this time, the jig 10 is arranged on the surface or separated from the surface 8 such that the end surface 14 of the jig 10 is parallel to the surface 8 of the detector 6. In the case of arranging them at a distance, appropriate means, for example, a spacer member (not shown) is used. The X-rays 4 emitted from the radiation source 2 are projected on the surface 8 of the detector 6 as shadows due to the absorption of the X-rays 4 at the portions of the patterns 20 and 30. FIG. 2 shows a state where the patterns 20 and 30 are projected.

FIG. 2 is a schematic plan view showing projected images 20a and 30a of the patterns 20 and 30 projected on the surface 8 of the detector 6, and FIG. 2A shows a state where the projected images 20a and 30a are completely coincident. (B) shows a state where the projected images 20a and 30a are shifted, respectively. (A) is a state where the center line 16 of the jig 10 coincides with the flux of the X-ray 4. That is, at this time, the projected image 20a
The center 24a of the projection image 30a and the center 34a of the projection image 30a completely coincide with each other in position, and are vertically and horizontally symmetric. In this state, since the surface 8 of the detector 6 is arranged orthogonal to the flux, it can be confirmed that the detector 6 and the flux are orthogonal to each other.

When the detector 6 is inclined with respect to the ray bundle, the projected images 20a and 30a are displaced as shown in FIG. This is because the projected image 20a of the pattern 20 near the radiation source 2 is projected at a position farther from the projected image 30a of the pattern 30 near the detector 6 when the vertical relationship between the ray bundle and the detector is shifted. is there. Therefore, the projected image 20a may be made to approach the projected image 30a as shown by the arrow 50, and the detector 6 or the radiation source 2 may be moved so that the centers 24a and 34a coincide.

Next, referring to FIG. 3, two patterns 20,
A magnification of 30 will be described. (A) is 100% magnification
FIG. 3 is a plan view similar to FIG. 2A, showing the projected images 20a and 30a at the time of FIG. (B) shows that the magnification of the projected image 20a is about 150%.
FIG. 13 is a similar plan view showing the case of FIG. If the X-rays 4 emitted from the radiation source 2 are parallel lines, two patterns 2
0, 30 are shown as projected images having the same diameter and one side dimension h as shown in FIG. However, in practice, since the X-rays are radiated after being diffused to some extent, the pattern 20 on the side closer to the radiation source 2 becomes an enlarged projected image 20b. The magnification is determined by the pattern 20, the radiation source 2, and the detector 6
In this embodiment, the dimension H of one side is about 1.5 times (about 150%) the dimension h, though it depends on the positional relationship between the two. This can be known by measuring the dimensions of the pattern 20 in advance.

Also, one side of the pattern 20 and the pattern 30
If the diameter of the pattern 20 is set to be the same, the enlargement ratio of the pattern 20 can be easily known by comparing the projected image 30a and the projected image 20b. If an object is arranged on the end face 12 which is the surface on the radiation source 2 side, the image of the object is displayed at a magnification of about 150% in this case. When the subject is a living body, for example, the size of the lesion can be obtained by back calculation from the projected image. Further, the end faces 12, 14
, The image can be captured at a desired magnification. At that time, each pattern 20, 3
Since there are a plurality of squares and circles of 0, comparison can be easily performed even when the enlargement ratio is large, and the enlargement ratio can be easily understood. In particular, when the two patterns are square and circular, it is easy to compare the dimensions of the projected images, and therefore, the enlargement ratio can be easily known.

As described above, the present invention has been described in detail.
The present invention is not limited to the above embodiment, and various modifications and changes can be considered. For example, the two patterns may be only a point indicating the center or a cross, but may be a combination of a cross and an X to facilitate identification of the two patterns. In addition, it is needless to say that the shape can be appropriately determined irrespective of these shapes. Needless to say, the combination of patterns may be reversed for center alignment.

Further, the pattern may be formed by forming the radiation transmitting material thickly and changing the transmittance of the thinned portion.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a radiation imaging system arrangement confirmation method using an arrangement confirmation jig according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a projected image of a pattern of an arrangement confirmation jig of the present invention projected on a surface of a detector, and FIG.
Indicates a state in which the projected images of the two patterns are completely matched, and (B) indicates a state in which the two projected images are displaced.

FIG. 3 is a diagram illustrating an enlargement ratio of two patterns.
FIGS. 3A and 3B are plan views similar to FIGS. 3A and 3B, wherein FIG. 3A shows a projected image when the magnification is 100%, and FIG.
Indicates the case of%

[Explanation of symbols]

 2 Radiation source 4 X-ray (radiation) 6 Detector 8 Detector surface 10 Arrangement confirmation jig 11 Support member 20, 30 Pattern 20a, 20b, 30a Projected image 24a, 34a Center

Claims (4)

[Claims] 1. A set of planar patterns each having a center formed by a radiopaque material are arranged coaxially and spaced apart from each other in parallel, and the center of one of the patterns in the set of patterns is arranged. Is aligned with a predetermined position on the surface of the detector that detects radiation, and is arranged in parallel with the surface, irradiates radiation from the radiation source, and in the projection image on the surface where the set of patterns overlap. Confirming that the line flux from the radiation source is perpendicularly incident on a predetermined position of the detector by confirming that the centers of the respective patterns coincide with each other. . 2. The method according to claim 1, wherein said one set of patterns is a pattern having a different shape. 3. A flat pattern having a center formed by a radiopaque material and having a set of patterns, and a supporting member for arranging the set of patterns coaxially and parallel to each other at a distance. An arrangement confirming jig used for an arrangement confirming method of a radiation imaging system, characterized in that: 4. An arrangement confirming jig used in the arrangement confirming method of a radiation imaging system according to claim 3, wherein said one set of patterns has different shapes.