JPH0619442B2 - Collimator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial field of application The present invention relates to a collimator used in a device that uses radiation, such as a single-photon emission CT.

(B) Conventional Technology In this type of conventional collimator, as shown in FIGS. 7 and 8, a collimator plate C made of a tungsten material is arranged in an assembly jig and the space is filled with a foamed resin H. As a unit, a plurality of these are alternately stacked with the shield to form an assembly.

FIG. 9 shows the structure of the release ring.

(C) The problem to be solved by the invention The shield material of the slice surface that basically constitutes the collimator, and the collimator plate that determines the decomposition of the plane orthogonal to this,
Although it is used for the same purpose in terms of the function of blocking radiation, it has been recognized that a material with different properties is required to form a structure. There was nothing to do.

The main reason for this is that the high-density material (metal) that serves as a radiation shielding material is hard tungsten or molybdenum, which is a sintered metal with a high melting point, or conversely, soft lead (lead alloy) with a low melting point.
It is thought that it was in a material with both extreme properties.

Tungsten, molybdenum, etc. are not suitable for fine processing such as slits due to their properties, and lead alloys are not difficult to process due to their properties, but lack in rigidity. All of them have the common property of being a high-density metal that shields radiation, and tungsten, molybdenum, etc. are suitable as collimator materials, but they are difficult to perform microfabrication, so they have the ideal structure of the sliced surface. It was not possible to provide a slit for fixing the collimator material that has been considered.

For this reason, to date, no collimator has a highly accurate assembly in which the collimator plate is arranged to penetrate through a slice plane composed of a plurality of collimators.

That is, it has the following problems.

Since the collimator plate is not supported by the slice plane, the rigidity in the horizontal plane is low and the structure is unstable.

Since the collimator plate is not structured to be supported by the slicing surface, it is difficult to obtain the angular placement accuracy of the collimator plate, and it is difficult to obtain the angular accuracy between the slicing surfaces even if the collimator assemblies are stacked and the slicing surface is made multiple. is there.

Since the collimator plates are individually arranged for each sliced surface, it is difficult to obtain the verticality of the entire assembly when the sliced surface is made plural.

 Manufacturing cost is high.

(D) Means for Solving the Problem The present invention solves the problem by utilizing the characteristics of two materials having different properties. First of all, the shield of the slice plane is to take advantage of the characteristics of the lead alloy that can be finely processed, but absorbs the radiation in order to compensate for the lack of rigidity which is the defect of the lead alloy and to obtain the accurate spacing of the slice plane. It is used as a composite material that has a rigidity that can withstand handling by joining foamed resins that are rarely used. That is, the slit material for inserting the collimator plate is precisely processed in the composite material in which the shield material of the sliced surface and the spacing material are combined, and a plurality of slits are stacked, and then the collimator plate is inserted.

(E) Work The sliced shield material prepared in this way is
It has sufficient processing accuracy and rigidity to enable the use of multiple sliced surfaces, and meets all the conditions required for an assembly.

Next, the collimator plate has high hardness and does not need to be complicatedly processed, but it is required to have a high rigidity because it is necessary to be assembled by penetrating many sliced materials to be stacked. Tungsten, molybdenum, etc. are materials that have this property completely.
In terms of processing technology, the wire cutter processing method can easily solve the problem because it is a tanzaku-shaped simple shape.

Further, since this single collimator plate penetrates the slice planes of a plurality of layers, there is no phase error between the layers and it also serves as a reinforcing material.

(F) Examples The present invention will be described below with reference to the drawings.

FIG. 3 shows the structure of the composite material. That is, 1 is a lead plate or a lead alloy plate as a high-density metal plate that serves as a shield material for the slicing surface, 2 is a material (for example, urethane foam) that constitutes a slice interval with little attenuation of radiation, and 3 is an adhesive (for example, low temperature). Active thermocompression sheet-like adhesive) 1,
Two or three layers are stacked and joined by a low temperature press machine. At this time, if a spacer for controlling the slice interval is set in the pressing device, the slice interval can be accurately maintained.

FIG. 1 shows a processed state of slits L which are arranged through the collimator plate in the composite material shown in FIG. The slit L is processed all around. At present, a cutting method using a carbon dioxide laser or the like is suitable as a processing method. FIG. 2 is an enlarged view showing a part of FIG.

FIG. 6 shows a state in which several tens of processed products capable of simultaneously controlling the shield of the slice surface and the spacing shown in FIG. 1 and penetrating the collimator plate 4 are stacked.

FIGS. 4 and 5 are views showing an assembled state of the collimator. The assembly is performed by setting the reinforcing plate 6 and the bolt 5 on a jig for controlling the outer periphery of the slice plate, inserting the slice plate into this, and slicing together. A spacer 8 for accurately maintaining the space between the plates is inserted, and this is repeated to obtain a predetermined number of layers.

Finally, the collimator plate 4 matching the slice height is inserted, the reinforcing plate 6 is placed, and the nut 7 is fixed to complete the assembly.
Reference numeral 10 is a fixing hole through which the bolt 5 is inserted.

The reinforcing cylindrical body 9 arranged on the side surface in FIG. 4 is performed by adhering a heat-welding plastic sheet or the like that absorbs little radiation, and is effective in increasing the strength of the entire collimator assembly.

The collimator according to the present invention is as described above, and has the following features.

The rigidity of the sliced surface is obtained by crimping the lead alloy plate used as the shield material of the sliced surface and the foam resin selected as the spacing material that does not absorb much radiation through the low temperature active thermocompression bonding sheet adhesive to form a composite material. Increase.

At the time of pressure molding, the thickness of the foamed resin that defines the distance between the sliced surfaces can be controlled by disposing a gap adjusting jig in the foamed resin layer.

At the same time, the flatness of the lead alloy plate can be adjusted.

A carbon dioxide gas laser processing machine or the like can be used to process the slit of the composite material in which the sliced surface shield material and the spacing material are combined. At that time, it is necessary to remove the adherence of pollutants (evaporants that absorb radiation) by the sliced surface shield material on the processed surface.

With respect to the sliced surface where a large number of sheets are superposed, the method of inserting the collimator plate perpendicularly to this is a reference hole and two pin holes provided at two opposing locations that are processed at the same time as the slits arranged in the sliced surface, Further, this also allows the jigs to be arranged by utilizing the processed surfaces inside and outside the sliced surface which is processed at the same time as the slits, and by using this as a reference, the assembly can be carried out accurately and in a short time.

The example of the ring-shaped collimator has been described above,
The collimator does not necessarily have to be ring-shaped, and can be applied to all collimators that require thin plates to be aligned, such as arcs, curved surfaces, and straight lines.

Further, it is obvious that the material does not need to be limited to lead for the slice plate, foam resin for the spacer, and tungsten, molybdenum for the collimator plate, and it is clear that all the materials satisfying the performance as the collimator are included. The adhesive for joining is not limited to the above.

Further, it is not limited to providing the spacer 8 or the cylindrical body 9 in the assembly.

The present invention also includes a slit for slicing from which the collimator plate is removed.

(G) Effect of the invention The collimator made by combining the two processed products prepared in this way combines high accuracy and rigidity in dividing many slice planes and angles, which was impossible with a collimator made by conventional manufacturing technology. It became possible to have it, and it also made it possible to manufacture at a cheap price. In addition, the composite of the sliced material (lead plate) and the spacing material (urethane foam) increases the rigidity of the processed product, and the thin lead plate (0, mm) can be used as the sliced material to overcome the problem. It is possible to have several tens of slice planes if combined with various processing means, and since a long collimator plate can be inserted in the slice plane, sampling precision that could not be obtained with a collimator manufactured by conventional manufacturing technology. It is possible to manufacture a collimator that can be expected.

The concept of the turbofan collimator can be realized inexpensively and with a structure having high rigidity.

[Brief description of drawings]

FIG. 1 is a diagram showing elements of a collimator according to the present invention, and FIG. 2 is a diagram showing an enlarged part of the collimator. FIG. 3 is a diagram showing the structure of the composite material, FIGS. 4 and 5 are diagrams showing the assembled state of the collimator according to the present invention, and FIG. 6 is a diagram showing the relationship between the assembly of the collimator according to the present invention and the collimator plate. FIG. 7 and FIG. 9 are diagrams showing a conventional configuration. 1 ... Slice material, 2 ... Low temperature active thermocompression sheet adhesive, 3 ... Slice spacing material, 4 ... Collimator plate, 5 ... Bolt, 6 ... Reinforcing plate, 7 ... Nut, 8 ... Spacer 9 ...... Cylinder

Claims (1)

[Claims] 1. A slit for inserting a collimator plate into a composite material obtained by joining a low-damping material that regulates the interval between the slice plates to a high-density metal plate that shields the slice surface, and a plurality of slits are formed. A collimator comprising a stack of sheets and a collimator plate inserted into a slit of this assembly.