JPH04116491A - Collimator for scintillator - Google Patents

Abstract

PURPOSE:To easily make possible the formation of fully thin septa by combining each thin plate in the form of lattice with the use of a comb-like grooves each other to form the septa while forming part of the thin plates with the use of a clad material. CONSTITUTION:A clad material 6a used for a thin plate 6 is formed of a laminated material 8 covering both side faces of a base metal 7. The base metal 7 is a material that is superior in workability, soft and can shield radiation, for instance, Ta and the like, and Cu and the like that has strength capable of reinforcement of the softness of the base metal 7 are used, and the shielding effect of radiation is not lowered when the ratio of the thickness occupying the base metal 7 is set at about 70-80% of the thickness of the thin plate 6. Comb-like grooves 9 formed at the time of press working are engaged therewith to form the lattice-like thin plates 6 to lock lock-grooves 11 of the inside face of a frame plate 4 so as to integrate with a frame body 5. Thereby, even if the thin plate 6 is thinned fully, a function for requesting for the septa can be surely possessed to compensate the lack of hardness in accordance with the quality of the base metal 7 and the laminated material 8 so as to obtain a collimator that is superior in workability and has high resolution.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a scintillator collimator used for detecting radiation with high sensitivity.

(Prior Art) Recently, in the diagnosis of diseases, X-ray photographs, X-ray CT images, radioisotope (RI) scintigrams, ultrasound images, positron CT images, thermograms, nuclear magnetic resonance (N
The role played by image diagnosis using MR) images and the like is playing a large role.

Among these, the RI scintigram depicts R1 inside the body as an image.

There is a Scintic camera as a device for obtaining such a scintigram. This scintillation camera uses a large circular scintillator, multiple photomultiplier tubes, and a computer to detect radioactivity injected into the body. In order to detect radiation from the target organ as highly sensitively as possible, a honeycomb-shaped collimator is installed on the front side of the scintillator.

Incidentally, such a collimator has regular hexagonal holes arranged in a regular manner, for example, 20,000 to 40,000 holes, and is made of lead that shields radiation.

When manufacturing the collimator using lead, the collimator is formed by setting a taper pin with a regular hexagonal cross section in a mold, pouring molten lead into the mold, and pulling out the taper pin after the lead has solidified. Furthermore, it is desirable that the thickness of the septa (walls) forming the boundaries of the holes be as thin as 0.2 mm or less in order to improve resolution.

However, if the thickness of the septa is less than 0.2 mm, the hot water may not flow during casting, the hole may be deformed, or the septa may be damaged when the pin is pulled out. Moreover, if there is even one defective point, the product cannot be used as a product, and repair is also difficult, resulting in a significant decrease in yield.

Therefore, it has been considered that the collimator may be made of tungsten instead of lead. In this case, a strip-shaped thin plate made of tungsten is cut by a press, and then comb-shaped grooves are formed by electrical discharge machining. The collimator is then formed by assembling the thin plates in a lattice pattern. However, since tungsten is very hard, it is difficult to perform press working or electric discharge machining, and particularly when press working comb-shaped grooves, the life of the mold becomes extremely short.

Moreover, due to its hardness, it is not possible to machine the comb-shaped grooves at the same time during press working, so the comb-shaped grooves have to be machined by electric discharge machining, which leads to poor productivity. .

(Problem to be solved by the invention) As described above, when the collimator is made of lead, it is not only difficult to form a thin septa, but also difficult to obtain accurate holes, and when the collimator is made of tungsten, it is difficult to form a thin septa. Something bad happens.

This invention was made based on the above circumstances, and its purpose is to provide a collimator for a scintillator that allows the septa to be made thinner and has good workability.

[Structure of the Invention (Means and Effects for Solving the Problems) In order to solve the above problems, the present invention provides a scintillator collimator in which a large number of through holes are defined by septa made of a radiation-shielding material. The above-mentioned septa consists of a strip-shaped thin plate in which comb-shaped grooves are formed at predetermined intervals, and each thin plate is assembled in a lattice shape by fitting each other's comb-shaped grooves,
A feature is that at least a portion of these thin plates is formed of a clad material.

According to this configuration, by using a material that shields radiation and has good workability for the base material of the cladding material that forms the thin plate, and using a high-strength material for the mating material that covers the base material, it is sufficient to A thin septa can be easily formed.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 5 shows a schematic diagram of the cinch camera 1.

This scintillator camera 1 has a scintillator 2. A collimator 3 is disposed on the front side of the scintillator 2. The patient K is placed within the field of view of this collimator 3.

A radioactive isotope is administered into the patient's body, and the gamma rays generated from this radioactive isotope are collimated through the collimator 3 and incident on the scintillator 2, causing the gamma rays to be incident at each position. Coefficient data can be obtained. By processing these gamma rays with a computer, a tomographic image including organ Z of the patient can be obtained.

The collimator 3 has W as shown in FIGS. 1 and 3.
It has a frame body 5 in which relatively thick band-shaped frame plates 4 made of materials such as (tungsten), Pb (lead), or Aρ (aluminum) are assembled into a rectangular frame shape. Inside this frame 5, a large number of strip-like thin plates 6 forming septa are arranged in a lattice shape as described later, so that inside the frame 5 there are many through holes 7 through which gamma rays pass. It is formed.

As shown in FIG. 3, the thin plate 6 is made of a cladding material 6a. The cladding material 6a includes a base material 7 and this base material 7.
It is formed from a laminated material 8 that covers both sides of the. The base material 7 has softness with excellent workability, and
A material capable of shielding radiation, such as Ta (tantalum), is used. The above-mentioned laminate material 8 is made of a material having strength capable of reinforcing the softness of the base material 7, such as Cu (copper), Ni nickel), stainless steel, F
One of materials such as e (iron) and pb (lead) is used. The proportion of the thickness occupied by the base material 7 is the thickness of the thin plate 6.
The thickness of the thin plate 6 is set to 70 to 80% of the thickness of the thin plate 6, so that the radiation shielding effect is almost the same as when the thin plate 6 is formed of Ta alone.

In the thin plate 6, when the flat plate-shaped cladding material 6a is pressed and punched out into a band shape, the comb-shaped grooves 9 are simultaneously pressed, as shown in FIG.

The comb-shaped grooves 9 are formed at predetermined intervals along the longitudinal direction of the thin plate 6, and are formed at approximately half the depth in the width direction. The thin plates 6 are assembled into a lattice shape by fitting the comb-shaped grooves 9 into each other. The peripheral portions (ends) of each of the thin plates 6 arranged in a lattice shape fit into engagement grooves 11 formed along the width direction on the inner surface of the frame plate 4 of the frame body 5, as shown in FIG. The frame body 5 and the lattice-shaped thin plates 6 are thereby integrated.

According to the collimator 3 having the above configuration, since the thin plate 6 can be made sufficiently thin, it is possible to obtain a collimator 3 with higher resolution than when the septa are formed only from lead. That is, when forming a septa with lead, its thickness is at most 25 to 0.28 mm, whereas if a thin plate 6 made of cladding material 6a is used, the thickness is 0.15 mm.
It is possible to make the cladding material 6a as thin as possible.
Because the septa are not easily damaged as in the case where the septa are formed of lead, it is possible to obtain a collimator 3 with high resolution.

Further, even if the thin plate 6 made of the cladding material 6a is made sufficiently thin, by using Ta for the base material 7, it can have a shielding effect against radiation, and the pliability of the base material 7 can be reduced by the laminating material 8. can be reinforced. In other words, even if the thin plate 6 is made sufficiently thin, it can reliably have the functions required as a septa. In addition, the materials of the base material 7 of the cladding material 6a and the laminate material 8 eliminate the lack of hardness that would occur when a septa is formed only with Pb, and W.
Since the poor workability that would be caused by forming the collimator 3 alone can be eliminated, the collimator 3 can have a high resolution due to these factors as well.

Note that this invention is not limited to the above-mentioned embodiment, and can be modified in various ways. For example, the cladding material 6 forming the thin plate 6
a is a mating material 8 provided on one side and the other side of the base material 7;
The materials may be different.

Further, as shown in FIG. 6, among the thin plates made of cladding material arranged in a grid pattern, cladding material 61a is provided along a predetermined direction, and cladding material 61a is provided along a direction crossing the predetermined direction. The thickness may be different from that of 61b. That is, the cladding material 61a may be made sufficiently thicker than the cladding material 61b. In this way, the shape of the through hole 7 can be changed in various ways, and the γ-ray shielding effect can be improved by the thick cladding material 61a.

Further, in the embodiment shown in FIG. 6, W
A thin plate 61c made of (tungsten) may also be used. In such a case, since the thin plate 61c is reinforced by the thick clad material 61a, it is possible to make it sufficiently thin and improve workability. In other words, even if the thin plate 61c is formed of W, by making it sufficiently thin, it is possible to prevent the workability from being greatly impaired.

Furthermore, in the present invention, as shown in FIG. 7, at least one of the laminates 8 provided on the side surfaces of the base material 7 may be formed of a multilayer film. This multilayer film is formed from a plurality of layers, for example, first to third layers F, to F3, made of different materials. In this way, the gamma ray shielding effect is significantly increased by the laminated material 8 made of a multilayer film.

[Effects of the Invention] As described above, in the case where the septa that define the through holes of the collimator are formed of thin plates, the thin plates are made into strip-shaped thin plates in which comb-shaped grooves are formed, and the mutual contact between each thin plate is provided. The comb-shaped grooves are fitted to form a uniform structure, and at least a portion of these thin plates is made of clad material.

According to such a configuration, by using a cladding material for the thin plate, it can be made sufficiently thin, so the resolution can be improved, and moreover, by selecting the material of the base material of the cladding phase and the composite material. It is possible to provide a shielding effect against radiation, workability, and strength without causing deformation or damage.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a part of a collimator showing an embodiment of the present invention, Fig. 2 is a side view of the same thin plate, Fig. 3 is an enlarged sectional view of the clad material forming the thin plate, and Fig. 4 is the same. FIG. 5 is a schematic view of the scintillator, FIG. 6 is an enlarged cross-sectional view of a part of the cladding material arranged in a grid, showing another embodiment of the present invention, and FIG. 7 is a diagram of the present invention. It is an enlarged sectional view of the laminated material showing still another example. 2...Scintillator, 3...Collimator, 5...
Frame body, 6... thin plate, 6a, 61a, 61b, crat material, 7... base material, 8... laminate material.

Claims (7)

[Claims] (1) In a scintillator collimator in which a large number of through holes are defined by a septa made of a radiation-shielding material, the septa are made of strip-shaped thin plates in which comb-like grooves are formed at predetermined intervals, and each thin plate is mutually adjacent to each other. 1. A collimator for a scintillator, characterized in that the comb-like grooves of the thin plates are fitted together in a lattice shape, and at least a part of these thin plates is formed of a cladding material. (2) The collimator for a scintillator according to claim (1), wherein a peripheral portion of the thin plates arranged in a lattice shape is surrounded by a frame. (3) The scintillator collimator according to claim (1), wherein among the thin plates arranged in a lattice shape, at least one thin plate along one direction is made of a clad material. (4) The collimator for a scintillator according to claim (1), wherein the base material of the cladding material is made of tantalum. (5) According to claim (4), the cladding material covering the base material of the cladding material is at least one selected from copper, nickel, stainless steel, lead, iron, or glass fiber reinforced plastic. Collimator for scintillator. (6) Claim (5) characterized in that the cladding material covering the base material has different materials on one side and the other side of the cladding material.
Collimator for scintillator described in. (7) The collimator for a scintillator according to claim (5), wherein the cladding material covering the base material of the cladding material forms a multilayer film formed by laminating a plurality of materials.