JP2000225177A - Sterilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of generating a vacuum leak form a gasket part inside and outside an electron beam accelerator caused by backscattering electron generated by an X-ray target. SOLUTION: This sterilizer is equipped with an electron beam accelerator 2 to generate and accelerate electron beam 6 in a vacuum atmosphere. On the tip end part, more concretely, on the tip end part of a scanning tube 12 constituting the electron beam accelerator 2, an X-ray target 30 is attached putting a gasket 42 therebetween. The X-ray target separates the atmospheres inside and outside the electron beam accelerator 2 and receives the electron beam 6 to generate an X-ray 34. The X-ray 34 is irradiated for sterilization to a matter 38 to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating an X-ray, which is generated by irradiating an X-ray target with an electron beam, to an object to be processed, such as a medical instrument or food, and sterilizing the object to be processed ( The present invention relates to a sterilization apparatus for performing a treatment (including sterilization in this specification), and more specifically, to an improvement in a structure of a portion for separating an atmosphere inside and outside an electron beam accelerator.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of this type of sterilizer. The sterilizing apparatus includes an electron beam accelerator 2 for generating and accelerating an electron beam 6 in a vacuum atmosphere,
And an X-ray target 30 that is provided outside the tip of the X-ray generator and receives the electron beam 6 to generate an X-ray (brake X-ray) 34.

More specifically, the electron beam accelerator 2 is a scanning type in this example, and the electron beam 6 generated by the electron beam source 4 is used.
Is accelerated by an accelerator 8 to an energy of, for example, several hundred keV to several MeV, and is scanned by a scanner (for example, a scanning coil) 10 in the front and back direction (Y direction) of the drawing in this example. It is configured to transmit through the provided window foil 20 and take it out in an irradiation atmosphere (for example, in the air).

[0004] The window foil 20 separates the vacuum atmosphere inside the electron beam accelerator 2 (specifically, the scanning tube 12 thereof) from the irradiation atmosphere outside the electron beam accelerator 2. , And is pressed and fixed by a window flange 24 with a gasket 22 for vacuum sealing interposed therebetween. The window foil 20 is made of, for example, titanium. The gasket 22 is, for example, a metal gasket, a hollow metal O-ring, or the like. The window foil 20 is shown as it flexes inward due to the pressure difference between the inside and outside of the scanning tube 12.

[0005] The window foil 20 generates heat due to the loss when the electron beam 6 passes therethrough. Therefore, the window foil 20 is usually of a forced cooling type.
In this example, a structure is employed in which cooling is performed by blowing high-speed air 28 from the cooling duct 26. However, a structure in which the window foil 20 is cooled by passing cooling water through a bar (not shown) supporting the window foil 20 may be adopted.

The electron beam 6 extracted in the irradiation atmosphere as described above collides with the X-ray target 30 and generates an X-ray 34 from that portion. The X-ray target 30
For example, it is made of a heavy (ie, high atomic number) metal such as tantalum or tungsten. Electron beam 6 is X-ray target 3
Since the X-ray target 30 loses almost all energy by colliding with zero and generates heat, the X-ray target 30 is usually of a forced cooling type. In this example, the X-ray target 3
A structure is adopted in which a coolant passage 32 is provided in the chamber 0 and the X-ray target 30 is forcibly cooled through a coolant such as cooling water. In this example, the X-ray target 30 has a structure that is curved upward in order to increase mechanical strength against internal refrigerant pressure, and the like.

[0007] X-rays 34 generated from the X-ray target 30
For example, the object to be treated 38 such as a medical instrument or food is irradiated to kill bacteria attached to the object to be treated 38 and sterilize the object to be treated 38. Workpiece 3
8 is conveyed by the conveyor 40 in the X direction orthogonal to the Y direction in this example.

The electron beam 6 irradiated on the X-ray target 30
Are scattered backward (that is, in the direction opposite to the traveling direction of the electron beam 6) as backscattered electrons 36, and the window flange 2
4. Since energy is consumed by the window foil 20, the scanning tube 12, and the like, they generate heat. Therefore, the scanning tube 12 also
Normally, a structure is employed in which cooling is performed forcibly by a cooling duct 16 through which a coolant such as cooling water passes.

When the irradiation atmosphere is air, ozone is generated when the electron beam 6 passes through the air layer between the window foil 20 and the X-ray target 30. An air diffusion device using an exhaust blower and a chimney (both not shown) is provided.

[0010]

In the sterilizer, when the X-rays are generated, the gasket 22 and the window flange 24 and the scanning tube 12 near the gasket 22 generate heat due to the incidence of the backscattered electrons 36. The gasket 22 is compressed by the expansion, and when no X-rays are generated, the compression by the thermal expansion disappears. Accordingly, a large repetitive load acts on the gasket 22 due to the repetition of the operation and the stop of the sterilizer, whereby the vacuum seal between the scanning tube 12 and the window foil 20 becomes incomplete, and a vacuum leak occurs during the interval. May be.

Therefore, the present invention reduces the possibility that a vacuum leak is generated from a gasket portion provided in a portion for separating the atmosphere inside and outside of an electron beam accelerator due to backscattered electrons generated from an X-ray target. Its main purpose is to:

[0012]

One of the sterilizing apparatuses according to the present invention is an electron beam accelerator for generating and accelerating an electron beam in a vacuum atmosphere, and is attached to a tip of the electron beam accelerator with a gasket interposed therebetween. And separates the atmosphere inside and outside the electron beam accelerator and receives the electron beam to
An X-ray target for generating a line is provided (claim 1).

According to the above configuration, since the X-ray target is attached to the tip of the electron beam accelerator with the gasket interposed therebetween, the gasket portion is where the electron beam is incident on the X-ray target, that is, the backscattered electrons are generated. It will be located in the horizontal direction of the part where it does. However, the intensity of the backscattered electrons generated from the X-ray target sharply decreases as the angle θ (see FIG. 1) with respect to the incident direction of the electron beam increases.

Accordingly, the intensity of the backscattered electrons incident near the gasket at the time of X-ray generation becomes very small, so that the heat generation near the gasket due to the backscattered electrons becomes very small, and the compression applied to the gasket by the thermal expansion due to the heat generation. The power is also reduced. As a result, the repetition of the operation and the stoppage of the sterilizer reduces the repetitive load acting on the gasket, so that the possibility of vacuum leak from the gasket portion can be reduced.

[0015]

FIG. 1 is a diagram showing an example of a sterilizer according to the present invention. Parts that are the same as or correspond to those of the conventional example shown in FIG. 4 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

In this sterilizer, the window foil 2 described above is used.
Instead of 0, the aforementioned X-ray target 30 is attached to the tip of the electron beam accelerator 2. That is, at the tip of the electron beam accelerator 2 (more specifically, the scanning tube 12 thereof), the X
A line target 30 is attached. Gasket 42
Is, for example, a metal gasket, a hollow metal O-ring or the like, similar to the gasket 22.

The X-ray target 30 has a function of separating a vacuum atmosphere inside the electron beam accelerator 2 (more specifically, the scanning tube 12 thereof) from an irradiation atmosphere outside the electron beam accelerator 2 and has been accelerated by the electron beam accelerator 2. And an operation of receiving the electron beam 6 and generating an X-ray 34.

The X-rays 34 generated from the X-ray target 30 are applied to the object 38 as described above, and the object 38 can be sterilized as in the conventional example.

In this sterilizing apparatus, since the X-ray target 30 is attached to the tip of the electron beam accelerator 2 with the gasket 42 interposed therebetween, the gasket 42 is a portion where the electron beam 6 is incident on the X-ray target 30, that is, Backscattered electrons 3
6 is located in the lateral direction of the portion where the 6 occurs. When the X-ray target 30 has a structure that is curved upward as in this example, the gasket 42 is located at a position that is lower than the side of the portion where the backscattered electrons 36 are generated.

However, the intensity distribution of the backscattered electrons 36 generated from the X-ray target 30 has a substantially Gaussian distribution, for example, as shown in FIG. 2, and the angle θ with respect to the incident direction of the electron beam 6 (FIG. 1). See larger)
The intensity of the backscattered electrons 36 sharply decreases.

Therefore, when the X-ray 34 is generated, the gasket 4
Since the intensity of the backscattered electrons 36 entering near 2 becomes very small, the heat generation near the gasket 42 due to the backscattered electrons 36 becomes very small, and the compressive force applied to the gasket 42 by the thermal expansion due to the heat generation also becomes small.

As a result, the repetition of the operation and stoppage of the sterilizer reduces the repetitive load acting on the gasket 42, so that the possibility of vacuum leakage from the gasket 42 can be reduced.

Further, according to this sterilizing apparatus, the window foil 20, the cooling duct 26 for cooling the same, and a blower for supplying air to the sterilizing apparatus are not required, so that the structure is simplified and the cost is reduced. Can be planned.

Further, in this sterilizing apparatus, the electron beam 6 is blocked by the X-ray target 30 and does not come out into the irradiation atmosphere, so that no ozone is generated even when the irradiation atmosphere is in the air. Therefore, an ozone treatment device or the like is not required, and the structure can be further simplified and the cost can be further reduced.

It should be noted that the X-ray target 30 allows air to flow through the refrigerant passage 32 instead of
Forcible air cooling may be performed by blowing high-speed air from the outside.

FIG. 3 is a view showing another example of the sterilizing apparatus according to the present invention. Explaining mainly the differences from the example of FIG. 1, in this sterilization apparatus, the generation of the electron beam 6 and the generation of the X-ray 34 can be switched by one apparatus.

That is, in this sterilizing apparatus, the electron beam accelerator 2
The electron beam 6 is deflected in the X direction (left-right direction on the paper) perpendicular to the Y direction, and the traveling directions thereof are different from each other in a first direction (a direction shown by a solid line in FIG. 3) and a second direction (FIG. 3). A deflector (for example, a deflection coil) 46 for switching to a direction indicated by a two-dot chain line is provided between the accelerator 8 and the scanner 10 in this example. This switching can be easily performed, for example, by reversing the polarity of the DC power supply that drives the deflector 46.

Further, the window foil 20 is provided on one side (left side in the drawing) of the tip of the electron beam accelerator 2 (more specifically, the scanning tube 12) with the gasket 22 interposed therebetween, and the other side ( (On the right side of the figure), the X
A line target 30 is attached. In this example, a center bar 44 that supports the window foil 20 and the X-ray target 30 is provided at the center of the tip of the scanning tube 12. The window flange 24 and the cooling duct 26 are the same as in the example of FIG.

The window foil 20 separates an inner vacuum atmosphere and an outer irradiation atmosphere on one side of the electron beam accelerator 2 (more specifically, the scanning tube 12 thereof), and is switched in the first direction. The electron beam 6 is transmitted.

The X-ray target 30 is an electron beam accelerator 2
On the other side of the scanning tube 12 (more specifically, on the other side), an inner vacuum atmosphere and an outer irradiation atmosphere are separated, and an X-ray 34 is generated by receiving the electron beam 6 switched in the second direction. I do.

Therefore, in this sterilizing apparatus, the generation of the electron beam 6 and the generation of the X-ray 34 can be switched by one apparatus, and therefore, the processing object 38 is sterilized by the irradiation of the electron beam 6. It is possible to switch between the treatment and the sterilization treatment by irradiation with X-rays 34. Accordingly, it is possible to perform various sterilization processes on the various objects 38.

For example, although the electron beam 6 has a lower penetrating power than the X-ray 34, if it is used as it is without converting it to X-rays, there is no conversion loss and the irradiation efficiency is high.
When the material 8 is a thin material such as a rubber glove, a syringe, or the like, it is convenient to irradiate the electron beam 6 to sterilize the material.

On the other hand, the conversion efficiency from the electron beam 6 to the X-ray 34 is, for example, 7 when the energy of the electron beam 6 is 5 MeV.
８8%, the irradiation efficiency is lower than when the electron beam 6 is irradiated as it is, but since the X-rays 34 have a higher penetrating power than the electron beam 6, the object 38 to be processed is, for example, a large number of objects. When the sterilized material is put in a container such as a cardboard box, it is convenient to irradiate the object 38 with X-rays 34 and to sterilize the contents at once.

When the X-ray 34 is generated using the X-ray target 30, the X-ray target 30 is attached to the tip of the electron beam accelerator 2 in the same manner as in the case of FIG.
2, the possibility of vacuum leakage from the gasket 42 can be reduced for the same reason as in the example of FIG. In addition, since the gasket 22 for the window foil 20 is also located in the lateral direction of the X-ray target 30, for the same reason as in the case of the gasket 42, the possibility of vacuum leak from the gasket 22 is reduced. be able to.

When the electron beam 6 is generated using the window foil 20, the window foil 20 transmits the electron beam 6, so
The generation of backscattered electrons from the X-ray target 30 is far less than that in the case of the X-ray target 30. Therefore, there is no problem that the backscattered electrons cause vacuum leakage from the gaskets 22 and 42.

In each of the above embodiments, the case where the electron beam accelerator 2 is of the scanning type has been described as an example. However, the present invention is of course also applied to the case of the non-scanning type in which the electron beam accelerator 2 does not scan the electron beam 6. be able to.

[0037]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, since the X-ray target is attached to the tip of the electron beam accelerator with the gasket interposed therebetween, the intensity of the backscattered electrons incident near the gasket when X-rays are generated is extremely high. The heat generation near the gasket due to the backscattered electrons becomes very small. As a result, the repetitive load acting on the gasket is reduced, so that the possibility of vacuum leakage from the gasket portion can be reduced.

Moreover, since a window foil, a cooling duct and a blower for cooling the same as in the conventional example are not required, the structure can be simplified and the cost can be reduced.

Further, since the electron beam is blocked by the X-ray target and does not enter the irradiation atmosphere, no ozone is generated even when the irradiation atmosphere is in the air. Therefore, an ozone treatment device or the like is not required, and the structure can be further simplified and the cost can be further reduced.

According to the second aspect of the present invention, the generation of the electron beam and the generation of the X-ray can be switched by one apparatus. The sterilization treatment by X-ray irradiation can be switched and applied. Therefore, various objects to be processed can be subjected to a sterilization process corresponding thereto.

Further, since the X-ray target is attached to the tip of the electron beam accelerator with a gasket interposed therebetween, the same effects as those of the first aspect of the present invention can be obtained with respect to backscattered electrons when X-rays are generated.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a sterilization apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of an intensity distribution of backscattered electrons.

FIG. 3 is a view showing another example of the sterilization apparatus according to the present invention.

FIG. 4 is a diagram showing an example of a conventional sterilization apparatus.

[Explanation of symbols]

 2 electron beam accelerator 6 electron beam 20 window foil 22 gasket 30 X-ray target 34 X-ray 36 backscattered electrons 38 workpiece 42 gasket 46 deflector

Claims (2)

[Claims] 1. An electron beam accelerator for generating and accelerating an electron beam in a vacuum atmosphere, and a gasket attached to the tip of the electron beam accelerator to separate the atmosphere inside and outside the electron beam accelerator. An X-ray target that receives the electron beam and generates X-rays. 2. An electron beam accelerator for generating and accelerating an electron beam in a vacuum atmosphere, and a first electron beam which deflects the electron beam in the electron beam accelerator so that its traveling directions are different from each other.
A deflector that switches between the first and second directions, and a gasket that is attached to one end of the tip of the electron beam accelerator with a gasket interposed therebetween, and separates the atmosphere inside and outside the electron beam accelerator on the one side. A window foil for transmitting the electron beam switched in the first direction, and a gasket attached to the other side of the other end of the tip of the electron beam accelerator, and an atmosphere inside and outside the electron beam accelerator on the other side. An X-ray target that separates and receives the electron beam switched in the second direction to generate X-rays.