JP2000325434A - Electron beam irradiating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the suppressing of a distribution of electron beams within a specified value without allowing the difference of the distribution of electron beams becoming larger, by irradiating one or more objects to be irradiated with electron beams in a state that they are housed in a cylindrical container and by selecting the thickness and material of the cylindrical container so that the distribution of electron beams between a surface region and a center region may be within a specified value. SOLUTION: A chain 5 is rotated in a specified speed with a belt conveyer 2 being conveyed in a state that cylinder bodies 8 containing respective dialyzers (objects to be irradiated) are placed on a line-shaped placing board 3. In this way, the cylinder bodies 8 are conveyed with rotating through an effective electron beam region of an electron beam irradiating device 7, while the dialyzers are irradiated with the electron beams having energy of 10 Mev from the electron beam irradiating device 7 through the cylindrical bodies 8. By doing so, the dialyzers 8 can be irradiated with the electron beam having the energy of 10 Mev without an irregularity through the cylindrical bodies 8. Moreover, the thickness and material of the cylindrical bodies 8 are selected so that the distribution of electron beams between the surface region and the center region of the dialyzer 8 may be set within 1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intended object such as sterilization while irradiating a high-energy electron beam to a three-dimensional and complicated shaped object to be irradiated, such as a medical device such as a blood processing module. The present invention relates to an electron beam irradiation device that achieves the object.

[0002]

2. Description of the Related Art Conventionally, dialysis fluid flowing around a hollow fiber capillary tube having a semipermeable membrane while blood is passed through the capillary tube causes uremia due to molecular diffusion or the like based on the concentration gradient of both fluids through the tube membrane. A dialyzer for hemodialysis for discharging a causative substance or the like is known. The dialyzer 1 has a ring-shaped capillary holder 21 for holding a large number of hollow fiber capillaries 35 at upper and lower ends thereof as shown in FIG. ,
These are covered with a cylindrical case 20, and a funnel-shaped blood inlet 26 and a blood outlet 27, which are screwed to upper and lower ends of the case 20 by caps 22 and 23, respectively, are fixed. Further, on the upper and lower side surfaces of the cylindrical case 20, a thin cylindrical dialysate inlet 24 and an outlet 25 are projected.

[0003] Such a hemodialysis dialyzer 1 must be used after being sufficiently sterilized as a matter of course because it circulates blood, and its sterilization methods include conventional high-pressure steam sterilization, ethylene oxide gas sterilization, and γ. X-ray sterilization and the like have been developed.

In recent years, attention has been paid to a method for sterilizing medical devices and the like by increasing the acceleration voltage of electron beam irradiation. The sterilization method using electron beam irradiation does not have the problem of heat resistance of the irradiated object unlike the high-pressure steam sterilization method, and has no concern about residual toxicity like the ethylene oxide gas method. Unlike the γ-ray irradiation method, the sterilization treatment time is not long and the treatment can be performed in a short time. When the power is turned off, the irradiation stops instantly,
There is no need to consider the storage of radioactive materials such as γ-ray irradiation facilities, and it has advantages such as high environmental safety and low cost. Further, the difference from γ-rays is that it is said that material deterioration is small. For this reason, there is an advantage that the range of material selection is wide.

However, the drawback of electron beam irradiation is that, unlike γ-ray irradiation, the penetrating power is small, and it is said that the transmission distance depends on the product of the density and thickness of the substance to be irradiated. Therefore, most products that have used electron beam irradiation as a sterilization method so far are surgical gloves, surgical sheets, surgical gowns, sutures,
And the like were relatively uniform in shape and made of a single member, and could be irradiated relatively easily. However,
A medical device called an artificial organ such as an artificial dialysis device or an artificial lung made of a hollow fiber has a three-dimensional and complicated shape as described above. In particular, as described above, the dialyzer 1 for hemodialysis is not merely a cylindrical shape, but a ring-shaped capillary holder 21 and a cap 2 at both ends of a thick cylindrical case 20.
2 and 23 are attached, and on the side of the case 20,
The dialysate inflow port 24 and the outflow port 25 in the form of a small cylinder are provided so as to protrude, so that the wall is thick (high density) and complicated in both the axial direction and the circumferential direction.

[0006] Therefore, in the dialyzer 1 for hemodialysis, the difference in the surface density of each part is large, and the dose distribution (the ratio between the maximum dose and the minimum dose) in one product at the time of electron beam irradiation is large, and the value is large. As a result, problems in safety, product management, performance, and the like have arisen. Specifically, if the irradiation standard is adjusted to the maximum dose, sterilization at the minimum dose position becomes insufficient, and if the irradiation standard is adjusted to the minimum dose, the artificial organ is generally made of an organic resin. In addition, excessive irradiation occurs at the position of the maximum dose, resulting in deterioration and coloring of the material.

For this reason, in order to suppress variations in the dose distribution due to irradiation, a double-sided irradiation method in which electron beams are irradiated from both front and back sides can be considered. However, an irradiation target having a large surface density such as the dialyzer 1 for hemodialysis is irradiated. High-energy electron beam irradiators are extremely expensive in terms of cost, and it is extremely difficult to install a plurality of these expensive devices in terms of profitability. Dose distribution (ratio between maximum and minimum doses) even when irradiation is performed on both sides of an object with a complex shape such as a combination
Was more than twice as large, and was not practical.

[0008]

In order to solve such a drawback, Japanese Patent Application Laid-Open No. Hei 8-275991 discloses a prior art in which a shield member for absorbing a high dose is used to absorb the dose. In this technique, an electron beam irradiation is performed by fixing a shielding sheet made of, for example, soft vinyl chloride containing tungsten to a portion where the dose is excessive, for each of the irradiated objects. It is not practical to fix the shield sheet to a portion where the dose is excessively large, since the fixing operation becomes extremely complicated.

Now, such a complex three-dimensional irradiation object is sterilized using an electron beam having a large energy. The maximum value of the electron beam energy allowed for industrial application is 10 MeV. Therefore, energy 5MeV,
A 10 MeV high energy electron beam irradiation device is commercially available, and the range of the 10 MeV electron beam is approximately 5 g.
/ Cm ² , when the electron beam of 10 MeV is irradiated, as shown in FIGS. 1 and 2, for example, the dose ratio is about 3 to 5 (g / cm ² ) when the product of the density and the thickness is about 3 to 5 (g / cm ² ). 10 Me as it is on the irradiated object (dialyzer)
When irradiated with an electron beam of V, when the diameter is around 5 cm,
The dose distribution ratio between the central region and the surface region may exceed 1.5 times. Here, in FIGS. 1 and 2, φ: the diameter of the dialyzer (cm), ρ: the specific gravity of the dialyzer (g /
cm ³ ), σ: 10 MeV electron beam range (5.192)
g / cm ² ). The Y-axis is the dose ratio (= center dose /
(Rated dose). The evaluation dose refers to the dose at the time of non-rotation.

In view of the above technical problem, the present invention reduces the electron dose distribution by 1.5 without increasing the dose distribution (the ratio between the maximum dose and the minimum dose) between the central region and the surface region.
It is an object of the present invention to provide a high-energy electron beam irradiating apparatus capable of suppressing the energy irradiation to within twice.

[0011]

According to the first aspect of the present invention,
In an electron beam irradiation method for achieving an intended purpose such as sterilization while irradiating a high-energy electron beam from a surface region to a central region of a three-dimensional irradiation object, one or more irradiation objects are placed in a cylindrical container. The thickness and material of the cylindrical container are selected so that electron beam irradiation is performed in the housed state and the dose distribution between the surface area and the central area is within 1.5. .

In this case, the product of the density and the thickness is 3 (g / cm).
² ) When irradiating the blood processing module with the electron beam, the object to be irradiated is angularly displaced with respect to the direction of electron beam irradiation every time the object rotates or passes through the electron beam irradiation area. It is preferable to perform electron beam irradiation while performing. Here, successively displacing the angle every time the electron beam irradiation area passes means that each time the object to be irradiated passes through the electron beam irradiation area by a belt conveyor or the like, the object is irradiated by a predetermined angle around the center axis of the cylindrical portion. It repeatedly passes through the electron beam irradiation area while changing the irradiation position of the object. For example, when passing three times, cumulative irradiation is performed by changing the angle by 120 °, and when passing five times, 72 ° each. Cumulative irradiation is performed with an angular displacement.

Preferably, the cylindrical container is a cylindrical or substantially elliptical container made of thin stainless steel, and preferably, the thickness and the material of the cylindrical container are changed to the surface area. It is preferable to select a stainless steel container having a thickness of about 0.1 to 2.0 mm, preferably 0.3 to 1 mm for the cylindrical container so that the dose distribution between the container and the central region is within 1.5. Is good.

That is, an organic resin may be used for the cylindrical container. However, the organic resin is colored or deteriorated by irradiation with an electron beam.
It has hygiene and ease of handling, and has a thickness of 0.1 to 2.0 mm, preferably 0.3 to 1.
1 and 2, the surface dose increases and the convex curve of the central dose shifts to the zero point side as compared with the case where the high energy electron beam is irradiated without a cylinder as shown in FIGS. 1 and 2. Therefore, as a result, the dose distribution ratio between the central region and the surface region can be made significantly lower than 1.5 times, and even if the irradiation object has a different thickness, the electron beam absorption amount of each part in the scanning direction can be reduced. This enables uniformization, for example, in the above-described container, which has no irradiation unevenness, and prevents coloring and deterioration of the resin-made irradiation object caused by excessive irradiation of unnecessary electron beams, while reducing irradiation of electron beams. Deterioration of quality such as poor sterilization can be prevented.

Of course, the present invention is not limited to stainless steel cylinders, but also includes organic resin represented by polysulfone, polycarbonate, polystyrene and Si.
A ceramic material such as C or quartz glass can be used.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

In this embodiment, electron beam irradiation was performed using the dialyzer 1 for hemodialysis shown in FIG. It is to be noted that a medical device to which the present invention can be most effectively utilized is preferably another blood processing module. Particularly in medical applications, the irradiation sterilization dose is 15 to 35 KGy in water immersion.
The degree is preferably used. Blood processing modules include plasma exchange therapy and artificial dialysis treatment (HD, HDF, H
F), artificial livers, endotoxin filters, bioreactors, and other medical and industrial uses. HD is Hemo Dialysis (hemodialysis), HD
F is Hemo DiaFiltration (hemofiltration dialysis), HF is Hemo
Filtration (blood filtration).

As described above, since the electron beam is difficult to reach by single-sided irradiation as described above, the module is irradiated with the electron beam while gradually changing the angle every time the laser beam is rotated or passed through the irradiation region of the electron beam. As described above, electron beam sterilization can be performed with a uniform dose (specifically, the ratio between the maximum dose and the minimum dose is 1.5 times or less). An electron beam irradiation device of 10 MeV was used as an electron beam sterilization device for such a complicated three-dimensional module.

FIGS. 1 and 2 show an embodiment of the present invention.
This will be described with reference to FIG. The object to be irradiated (da
1) is filled with a liquid such as a dialysate in a cylindrical case.
The hemodialysis dialyzer 1 shown in FIG.
mm and 0.6 mm thickness in each stainless steel cylindrical container
And not put in the stainless steel cylindrical container
10MeV for each exposed naked
Irradiating the electron beam, the surface dose and the central dose,
The results of the respective measurements are shown in FIGS. In the figure, φ:
Dializer diameter (cm), ρ: dialyzer specific gravity
(G / cm ^Three), Σ: 10 MeV electron beam range (5.
192 g / cm^Two).

When examining the measurement results, when there is no cylinder, for example, in the case of the dialyzer 1 for hemodialysis,
The dose distribution (surface dose /
When the largest diameter of the central dose was 5 cm, the surface dose was 0.8, the central dose was 1.2, and the dose distribution was 1.5 times. On the other hand, when the stainless steel cylinder is irradiated with an electron beam, the surface dose is 0.9, the central dose is 1.12 and the dose distribution is 1.24 when the thickness of the stainless steel cylinder is 0.3 mm. It has been greatly reduced by a factor of two. When the thickness of the stainless steel cylinder is 0.6 mm, the surface dose is 0.92, the central dose is 1.07, and the dose distribution is further reduced to 1.16 times.

Next, a specific apparatus for achieving the present invention will be described. 3 and 4 show an electron beam sterilizing apparatus according to an embodiment of the present invention using the stainless steel cylinder. FIG. 3 is a plan view, and FIG. 4 is a side view as seen from the conveyor transport side. 3 and 4, a hollow cylinder 8 accommodating the dialyzer 1 has a thickness of 0.1 mm as shown in FIGS.
Although a cylindrical stainless steel cylinder 8 having a thickness of 3 mm and a wall thickness of 0.6 mm was used, the stainless steel cylinder does not necessarily have to be a cylinder, and may have an elliptical cross section, an oblong cross section, etc. Can be formed.

In the drawing, a placing table 3 is arranged on the belt surface of the belt conveyor 2 along the conveying direction.
The cylinders 8 are arranged on the upper side so as to stand vertically. A rotating shaft 4a is vertically provided below the belt conveyor 2 of the placing table 3, and a driven sprocket 4 is provided at the end of the rotating shaft.

The electron beam irradiator 7 has a flat horn-shaped scanning horn formed in a divergent shape and is vertically arranged, and a pair of scanning magnets (not shown) provided on the base side of the horn provides a central axis of the cylindrical body 8. It is configured to perform beam scanning in the vertical direction along the line. The electron beam irradiation device 7 is configured so that an electron beam having an energy of 10 MeV can be emitted from the irradiation window at the exit of the scanning horn.

On the other hand, an endless drive chain 5 is disposed at a position facing the driven sprocket 4, and the drive chain 5 includes sprockets 6A and 6 provided on both left and right sides.
B and the first sprocket 6
A is a driving sprocket connected to a speed control motor, and the placing table 3 conveyed along the belt conveyor 2 into the electron beam irradiation area uses the driven sprocket 4 provided on its lower surface side as the endless chain. A drive sprocket 6 meshing with the chain 5 is rotatable by a speed control mechanism 11.

According to this embodiment, the chain 5 is circulated at a predetermined speed while the belt conveyor 2 is conveyed in a state where the cylinders 8 each containing the dialyzer 1 are placed on the row of the pedestals 3. While irradiating the dialyzer 1 with an electron beam having an energy of 10 MeV from the electron beam irradiation device 7 via the cylinder 8, the cylinder 8 is transported while rotating the effective electron beam irradiation area of the electron beam irradiation device 7. Accordingly, the electron beam having an energy of 10 MeV is irradiated from the electron beam irradiation device 7 to the dialyzer through the cylinder 8 without unevenness. 1 and 2 in such an apparatus.
Can be smoothly achieved.

[0026]

As described above, according to the present invention, the dose distribution between the central area and the surface area (the ratio between the maximum dose and the minimum dose).
Of the electron dose distribution without increasing the aperture of 1.
It can be suppressed within 5 times.

[Brief description of the drawings]

FIG. 1 shows an example in which the dialyzer shown in FIG. 5 is placed in a 0.3 mm-thick stainless steel cylindrical container, and the dialyzer exposed without being exposed in a cylindrical container is irradiated with an electron beam. It is the graph figure which measured the surface dose and the center dose, respectively.

FIG. 2 shows an example in which the dialyzer shown in FIG. 5 is placed in a 0.6 mm-thick stainless steel cylindrical container, and the one exposed naked without being put in the cylindrical container is irradiated with an electron beam. It is the graph figure which measured the surface dose and the center dose, respectively.

FIG. 3 is a plan view of the electron beam sterilizer according to the embodiment of the present invention.

FIG. 4 is a side view as viewed from a conveyor conveyance side in FIG. 3;

FIG. 5 shows the shape of a dialyzer for hemodialysis, which is an object to be irradiated according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 dialyzer for hemodialysis 2 conveyor 3 table 7 electron beam irradiation device 8 cylinder

Claims (3)

[Claims] 1. An electron beam irradiation method for achieving an intended purpose such as sterilization while irradiating a high-energy electron beam from a surface region to a central region of a three-dimensional irradiated object. The thickness and material of the cylindrical container were selected so that the electron beam irradiation was performed while being housed in the cylindrical container, and the dose distribution between the surface area and the central area was within 1.5. An electron beam irradiation method, characterized in that: 2. When irradiating an electron beam to a blood processing module having a product of density and thickness of 3 (g / cm ² ) or more, the object to be irradiated rotates or passes through an electron beam irradiation area with respect to the electron beam irradiation direction. 2. The electron beam irradiation apparatus according to claim 1, wherein the electron beam irradiation is performed while sequentially changing the angle every time. 3. The electron beam irradiation method according to claim 1, wherein said cylindrical container is a stainless steel container having a thickness of 0.2 to 1.0 mm.