JPH0575993B2 - - Google Patents

Description

[Detailed description of the invention] (A) Industrial application field This invention is a single photon emission CT
The present invention relates to a method for manufacturing a collimator used in devices that utilize radiation, such as the following.

(B) Prior art As shown in Figures 9 and 10, a conventional collimator is a single unit in which a tungsten plate C serving as a collimator is placed in an assembly jig and the space is filled with foamed resin H. It is constructed by assembling and stacking multiple sheets alternately with shielding materials.

(C) Problem to be solved by the invention The shielding material for the sliced surface and the collimator plate that defines the separation of the plane perpendicular to this, which basically constitute the collimator, are used for the same purpose in terms of the function of blocking radiation. It has been recognized that materials with different properties are required to form structures. However, no proposal has been made to specifically solve this problem.

The main reason for this is that the high-density material (metal) that serves as the radiation shield material is either hard tungsten or molybdenum, which is a sintered metal with a high melting point, or conversely, lead (lead alloy), which is soft and has a low melting point. This is thought to be due to the material having extreme properties.

Due to their properties, materials such as tungsten and molybdenum are not suitable for micromachining such as slits, and lead alloys do not have much difficulty in machining due to their properties, but they lack rigidity. Tungsten, molybdenum, etc. are suitable as collimator materials because they all have the common property of being high-density metals that shield radiation, but it is difficult to perform microfabrication, so the ideal structure of the sliced surface It has been thought that a slit for fixing the collimator material could not be provided.

For this reason, to date, there has been no highly accurate assembly in which a plurality of collimators are arranged to penetrate through the collimator plates in the slicing plane.

To summarize the above, since the collimator plate is not supported on the slice plane, that is, it is supported only at the bolt position, the rigidity in the horizontal plane is low and the structure is unstable. In addition, since the collimator plate is not structured to be supported by the slice plane, it is difficult to obtain angular placement accuracy of the collimator plate, and even if collimator assemblies are stacked to create multiple slice planes, it is difficult to obtain angular accuracy between the slice planes. It is.

Furthermore, since the collimator plates are individually arranged for each slice surface, when multiple slice surfaces are used,
It has the disadvantage that it is difficult to obtain verticality throughout the assembly.

Therefore, it has the disadvantage that the manufacturing cost increases as a result.

(D) Means for solving the problem In order to solve the problem by utilizing the characteristics of these two materials with different properties, the present invention first makes it possible to perform fine processing on the shield of the sliced surface. In other words, in order to compensate for the lack of rigidity, which is a drawback of lead alloys, and to obtain accurate spacing between sliced surfaces, foamed resin that absorbs little radiation is bonded to create a composite material (composite material) that has the rigidity to withstand handling. )
Use. The fine slits for the collimator plate are processed using a non-contact energy beam such as a carbon dioxide laser processing machine. At this time, if cutting is performed from the foamed resin side, a cut surface will be created that will not contaminate the interval between the sliced surfaces and absorb radiation.

(E) Action After accurately machining a slit for inserting a collimator plate into a composite material that combines a shielding material and a spacing material on the sliced surface, and stacking multiple sheets, the collimator plates are inserted through them to overlap them. The requirements for accuracy and high rigidity of the spacing between the slice planes and the geometrical position of the collimator plate are satisfied.

More specifically, a lead alloy plate as a shielding material for the sliced surface and a foamed resin selected as a spacing material that absorbs little radiation are bonded together using a low-temperature-activated thermocompression sheet adhesive, etc. to form a composite material. The rigidity of the sliced surface is guaranteed.

At the same time, during molding, by placing a spacing adjustment jig on the foamed resin layer, the thickness of the foamed resin that defines the spacing between sliced surfaces is controlled, and at the same time, the flatness of the lead alloy plate is also adjusted.

A carbon dioxide laser processing machine or the like is used to process the slits in the composite material that combines the sliced face shield material and the spacing material. At that time, in order to remove contaminants (deposits that absorb radiation) attached to the sliced surface shield material on the processed cut surface, if the cutting process is performed from the foamed resin side, lead etc. will melt and flow into the foamed resin and the distance between the sliced surfaces. There is no such thing as contaminating the air and absorbing radiation.

(F) Embodiments The present invention will be described below with reference to embodiments shown in the drawings.

As shown in FIG. 1, slice material 1 (for example,
A lead or lead alloy plate (thickness 0.5 mm) and a material 2 that is highly transparent to X-rays, gamma rays, etc. (for example, a foamed acrylic plate with a thickness of 4 to 2 mm) are bonded together with an adhesive 3 (for example, low-temperature activated thermocompression bonding). A composite board is produced by closely bonding the sheets using adhesive (sheet adhesive). For example, the size is
The size shall be 400×400mm.

About 40 ring-shaped collimators each having a shape shown in FIG. 2 and having many slits 4' (width approximately 0.5 mm) are processed using a carbon dioxide laser processing machine.

That is, as shown in FIG. 3, the material is laser-processed using, for example, a carbon dioxide laser processing machine M. In this case, as shown in the figure, the material is irradiated with laser light L from the foamed acrylic board 2 side. In this case, since the sliced material 1, which is a lead material, is slitted last, the lead does not melt and flow into the foamed acrylic plate 2, and extremely good slit holes are made.

The single collimator shown in FIG. 2, which has been processed as described above, is inserted into the bolt hole 6H as shown in FIG.
Using this method, 40 layers are superimposed on bolt 6. In addition, in FIG. 2, A is a plan view and B is a sectional view.

When stacking the individual units S, since the foamed acrylic plate 2 is an elastic material, it is necessary to prevent the units from being deformed by tightening with the bolts 6. Therefore, as shown in FIG. 5, a space is formed inside the foamed acrylic plate 2 only at the portion tightened by the bolt 6, and a spacer 5 is interposed in this portion.

For the assembly of the single units S, a collimator is completed by inserting and gluing the collimating material 4 as shown in FIG. Finally, as shown in FIG. 6, the reinforcing frame 7 is fitted into the upper and lower ends and fixed with screws 8.

In addition to those shown in the above embodiments, according to the present invention, various types of collimators such as a multi-ring type collimator (FIG. 7) and a bow-shaped collimator (FIG. 8) can be manufactured.

In addition, it is possible to attach a film that is highly transparent to X-rays, gamma rays, etc. to the outer periphery, fix a reinforcing plate by welding, or glue the sliced surfaces and the collimator material together at the same time to glue and integrate the entire collimator. can also be considered.

(G) Effects of the invention The shielding material for the sliced surfaces prepared in this manner has sufficient machining accuracy and rigidity to enable the use of multiple sliced surfaces stacked on top of each other, and meets all the conditions necessary for an assembled product. meets the requirements.

Next, high rigidity can be easily obtained by assembling a tanzak-shaped tungsten/molybdenum collimator plate processed by a wire cutter method or the like by penetrating and bonding it to multiple layers of sliced material. The concept of a turbofan collimator can be provided at low cost and with a configuration having high rigidity.

The collimator made by combining the two processed products prepared in this way is able to achieve both high precision and rigidity in the division of numerous slice planes and angles, which was impossible with collimators made using conventional manufacturing techniques. Ta. Furthermore, it was possible to manufacture it at a low price.

The above can be summarized as follows.

1. A collimator with unprecedented multi-layer slicing and high resolution can be created.

2. Multi-ring type collimator can be made.

3. Increased rigidity and reliability of the collimator, enabling diagnosis through high-speed measurement.

4. Improved accuracy and reliability as a collimator.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the material of a single collimator according to the present invention, FIG. 2 is a diagram showing the single unit, FIG. 3 is a diagram showing the slit processing method, and FIGS. 4 to 6 are diagrams showing the assembly process. FIGS. 7 and 8 are diagrams showing modified examples, and FIGS. 9 and 10 are diagrams showing conventional configurations. 1...Slice material, 2...Foamed acrylic board, 3
...adhesive goods, 4 ... slit material, 5 ... spacer, 6 ... bolt, L ... laser beam, M ... laser processing machine, S, S' ... collimator unit.

Claims (1)

[Claims] 1 A composite frame is created by bonding a low-attenuation material for radiation that regulates the spacing between the slice plates to a high-density metal plate that shields the slice plane, and a slit for inserting the collimator plate is inserted into the frame using a laser, etc. A method for manufacturing a collimator, characterized in that processing is performed using a non-contact energy beam or the like.