JP2003153985A - Quality determination system of electron beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quality determination system of an electron beam irradiation device capable of accurately determining the dose of electron beams irradiated to an irradiated article. SOLUTION: The quality determination system is for guaranteeing the dose of electron beams to be irradiated to an irradiated article by the electron beam irradiation device for achieving the initial purpose such as sterilization by irradiating electron beams. In the quality determination system, the time to start the irradiation and the time to finish the irradiation of electron beams to the irradiated article are calculated from the time series position information and the conveyor speed detected by at least one sensor disposed inside an electron beam irradiation chamber on the upstream side or downstream side of the electron beam irradiation region, and it is determined whether the dose of electron beams extracted from the time series data such as the output, irradiation width, and conveyor speed of the electron beam irradiation device recorded at the same time holds a prescribed quantity within the electron beam irradiation time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation apparatus for irradiating an irradiation object such as a medical device or food with an electron beam irradiation apparatus for achieving an intended purpose such as sterilization while sterilizing an electron beam. Relates to a quality determination system for an electron beam irradiation apparatus, which can determine whether or not a prescribed amount that can circulate an irradiation object as a product is satisfied.

[0002]

2. Description of the Related Art Conventionally, sterilization such as high pressure steam sterilization, ethylene oxide gas sterilization, γ-ray sterilization, etc. has been conventionally performed for foods, medical instruments and the like that require sterilization before being shipped as products. It has been subjected. However, each of the above sterilization treatments has its own problems. For example, the high pressure steam sterilization treatment requires high pressure resistance and heat resistance for the sterilization target, and the treatment target is limited. In chemical processing, there is a risk of residual toxicity in the sterilized object, and since these methods are batch type, the processing amount is small,
Not suitable for large-scale processing. Further, in the γ-ray sterilization treatment, there is a problem that the management of radioactive substances is complicated and there is a possibility that it will affect the environment.

Therefore, in recent years, attention has been paid to sterilization treatment by electron beam irradiation. The processing time is very short, from a few seconds to a few minutes, and since it can be processed continuously, large-scale processing is possible. In addition, it has the advantages that the inner surface of the object to be sterilized can be sterilized, the cost is low, and the material deterioration is small compared to gamma rays, and the range of material selection is wide.

The applicant of the present invention has found that as a method for efficiently irradiating an irradiation object with such electron beam irradiation, Japanese Patent Application No. 2000-191.
797 has been filed. According to this, as shown in FIG. 5, such an electron beam irradiation system includes a sterilization chamber 25 surrounded by a shielding wall 22 such as concrete, and an electron beam irradiation system disposed at a substantially central portion of the sterilization chamber 25. It comprises an apparatus 10 and conveyors 12, 13, 14 extending from the sterilization chamber entrance 26 to the exit 27 through the electron beam irradiation apparatus 10. In such a system, the conveyor speed of the irradiation conveyor 14 for irradiating the electron beam 20 is set lower than that of the roller conveyor 12, and a stopper 17 is provided so that the irradiation target can be closely contacted and conveyed under the electron beam irradiation area. It is configured. As a result, waste of electron beams can be eliminated and efficient sterilization can be performed. In this way, in the sterilization process in such an electron beam irradiation apparatus, a plurality of conveyors are appropriately connected in series, and generally have a total length of about 90 m, and after the irradiation target is carried in from the entrance of the sterilization chamber It will be delivered in about 15 minutes.

On the other hand, in order to circulate an irradiation object sterilized by such an electron irradiation apparatus as a product, the electron beam dose applied to the irradiation object must satisfy a specified value. For this reason, conventionally, a product to be sterilized is mixed with an inspection product that is regularly equipped with a dosimeter, and after sterilization, the dose absorbed by the inspection product is measured before and after the product. The method of judging the quality of was adopted. However, in such a method, it is very time-consuming to install a dosimeter on the inspection product, extract the inspection product, and record the dose, which causes a problem in productivity.

Therefore, recently, a method of determining the dose based on the irradiation start time / end time of each product described in the sterilization daily report has been adopted. This is the sterilization chamber inlet 2 shown in FIG.
The irradiation start time is the time when the product 11 passes through 6 (point O),
The irradiation dose estimated from the parameters such as the accelerator output, the irradiation conveyor speed, and the electron beam irradiation amplitude corresponding to each time recorded at the same time is defined as the irradiation end time with the time when passing through the exit 27 (point R) as the irradiation end time. This is a method of determining whether or not the specified amount is satisfied from the start time to the end time.

[0007]

However, in such a conventional method, the electron beam irradiation start time / end time is set at the sterilization chamber outlet and the sterilization chamber inlet respectively, so that the time when the product is actually irradiated with the electron beam is set. There is an error of about 5 minutes each. As a result, there is a possibility that the dose estimated from the above parameters may differ from the dose actually irradiated to the product. Therefore, in view of the above technical problem, it is an object of the present invention to provide a quality determination system for an electron beam irradiation apparatus that can accurately determine the electron beam dose applied to an irradiation target.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an electron beam irradiation apparatus for irradiating an object with an electron beam irradiation apparatus for irradiating an electron beam to achieve an initial purpose such as sterilization. In a quality determination system that guarantees a dose, an electron beam irradiation start time and an irradiation end time for the object to be irradiated are determined by one or more sensors arranged in an electron beam irradiation chamber upstream or downstream of the electron beam irradiation region. Calculated from the time-series position information and the conveyor speed, the electron beam dose of the electron beam irradiation apparatus is derived from the output information and the like in almost synchronization with the time-series position information, and a predetermined amount within the electron beam irradiation time. Is determined.

Further, the invention according to claim 2 is a quality judgment system for guaranteeing an electron beam dose applied to an object to be irradiated by an electron beam irradiation device for irradiating an electron beam to achieve an initial purpose such as sterilization. In the above, in the electron beam irradiation start time and irradiation end time of the object to be irradiated, time series position information and conveyor by two or more sensors arranged in the electron beam irradiation chamber on the upstream side and the downstream side of the electron beam irradiation region. It is calculated from the velocity, and the electron beam dose of the electron beam irradiation apparatus is derived from its output information and the like in synchronism with the time-series position information, and the electron beam dose is a predetermined amount within the electron beam irradiation time. It is characterized by determining whether or not it is held.

The quality assurance of the irradiated object that has been sterilized by electron beam irradiation is determined by whether or not the irradiation dose to the irradiated object satisfies a specified value. Further, the irradiation dose can be estimated by parameters such as accelerator output, electron beam amplitude and conveyor speed. According to the first and second aspects of the present invention, the time when the electron beam is actually applied to the irradiation target can be recorded almost accurately,
By correlating with the dose estimated from the parameter at the same time, the irradiation dose to each irradiation object can be accurately determined.

That is, as shown in FIG. 3, conventionally, during the period from the time t _O when the object to be irradiated is carried into the sterilization chamber to the time t _{R when} it is carried out from the sterilization chamber, it is several tens minutes of Δt _1. If it is determined that the dose parameter is large or the dose inferred from the dose parameter is satisfied, the dose error is large, and the dose is insufficient due to a failure of the accelerator, etc. All the products existing in the sterilization room at the time may be defective products, and there was a problem in productivity. However, according to this invention, the dose corresponding to a short time of several tens of seconds to several minutes of Δt _{2 at} the time t _{Q at which} the irradiation region ends from the time t _P at which the electron beam is actually irradiated to the irradiation object is set. Since the determination can be made, the dose can be measured almost accurately, and the above problems can be solved.

The electron beam irradiation start time and end time may be derived from a single sensor, or the irradiation start time and end time may be obtained from sensors provided on the upstream side and the downstream side of the electron beam irradiation area, respectively. You may derive each one. Further, the method of calculating each time may be calculated from the time-series position information by the sensor, the conveyor speed, and the conveyor length from the sensor to the irradiation area, or may be derived empirically.

The sensor according to claim 1 or 2 is
It is characterized in that it is installed at a position where the influence of radiation generated by electron beam irradiation is small. For example, when a high-energy electron beam is used, a bremsstrahlung phenomenon occurs in which X-rays are emitted in the Coulomb field of atomic nuclei when the electron beam passes through a substance. As a result, deterioration of the material forming the sensor is likely to occur. Therefore, in order to prevent a significant decrease in the life of the sensor, the structure according to claim 3 reduces the deterioration of the sensor and reduces the life of the sensor. It is possible to improve.

In particular, according to the fourth aspect, the position at which such a sensor is installed may be a position at which the radiation strikes the sensor after being diffracted at least once, preferably once or twice. According to the invention, the electron beam irradiation start time and the end time are set at a position where damage of radiation such as braking X-rays is small as described in claim 3 and as close to the electron beam irradiation region as possible. It is possible to record more accurately, and it is possible to further reduce the error in the irradiation dose.

According to a fifth aspect of the invention, a stopper and a cutout sensor are provided on the upstream side of the electron beam irradiation area,
A quality assurance system for the electron beam irradiation apparatus, wherein the irradiation object is configured to pass through the electron beam irradiation region in close contact, and the sensor according to claim 1 or 2 is the cutout sensor. Characterize. Japanese Patent Application 200 mentioned above
In the case of the electron beam irradiation apparatus proposed in 0-191797, the product cutting stopper and the cutting sensor are the positions where the radiation damage is the least and the position is close to the electron beam irradiation region. Therefore, a rational system can be obtained by diverting the sensor. In general, since a plurality of sensors are installed in the sterilization chamber for various purposes, other sensors may be used as well as the cutout sensor.

Furthermore, the present invention according to claim 6 uses at least two or more of the above-mentioned sensors and uses a sensor having a failure detection function, and when one sensor fails, another sensor can be used. It is characterized by being.
As a result, even if the sensor fails, the system can be operated with high efficiency without stopping the production line.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless specifically stated otherwise, and are merely illustrative examples. Not too much. 1 is a schematic configuration diagram of a quality determination system of an electron beam irradiation apparatus according to an embodiment of the present invention, FIG. 2 is a side view of an electron beam irradiation region, (a) is a side view at the time of starting electron beam irradiation, (B) is a side view at the end of electron beam irradiation, FIG. 3 is a graph showing various dose parameters and irradiation time, and FIG. 4 is a plan view showing a radiation region in the electron beam irradiation apparatus of the present embodiment.

In FIG. 1, 10 is an electron beam irradiation device for generating and outputting an electron beam, 12A and 12B are conveyors, 14 is an irradiation conveyor, 22 is a shielding wall made of concrete or the like, 25 is a sterilization room, 17 is a cutting stopper,
Reference numerals 15, 16, 23 and 24 are sensors. In the present embodiment, the product to be irradiated is not particularly limited to medical instruments, foods, etc., and an electron beam irradiation device such as energy output is appropriately selected according to each irradiation target.

Further, in order to efficiently perform the electron beam irradiation, the irradiation conveyor 1 is carried by the transfer conveyors 12A and 12B so that the object to be irradiated is conveyed in close contact on the irradiation conveyor 14.
The speed of 4 is made small, and the cut-out stopper 17 and the cut-out sensor 14 provided at the position where the radiation generated from the electron beam irradiation region does not directly hit are appropriately controlled to bring the conveyed irradiation object into close contact. Since the irradiation conveyor 14 and the transfer conveyor 12B near the electron beam irradiation area are severely deteriorated by the influence of radiation such as braking X-rays generated from the electron beam irradiation area, it is preferable to use a stainless material such as SUS having high durability. Good.

For the above reasons, the sensors installed for various purposes in the sterilization chamber 25 are installed at positions where the influence of the radiation is small. As shown in FIG. 4, the region A, which is directly exposed to the radiation generated from the electron beam irradiation region, has extremely strong radiation, and thus the material is particularly deteriorated. Therefore, it is not preferable to install a precision machine such as a sensor in the area A. Therefore, it is advisable to install the radiation in the region B in which the radiation is diffracted once or in the region C in which the radiation is diffracted twice or more. further,
In order to accurately record the electron beam irradiation start / end time, the position of the sensor is selected to be the position closest to the electron beam irradiation region within the range where the influence of the radiation is small.

In this embodiment, such a sensor is used as the cutout sensor 15 shown in FIG. 1, the time when the irradiation object passes through the position E of the cutout sensor 15 is recorded, and the electron beam irradiation area start point P is recorded from that time. The time at which the irradiation target passes through the point P, that is, the electron beam irradiation start time is calculated from the conveyor length up to and the conveyor speed. Similarly, the conveyor length from the electron beam irradiation start point P to the end point Q and the irradiation conveyor 1
The time at which the irradiation end point Q is passed is calculated from the speed of 4 and the position information of the irradiation object is recorded as time series data. It should be noted that each time may be calculated using the sensor 16 similarly to the sensor 15, or in order to further improve the accuracy of the data, the sensors 15 and 16 may be used to calculate the time from the sensor 15. The irradiation start time may be calculated from the sensor 16 as the irradiation end time. Further, the electron beam irradiation start time and end time may be obtained empirically.

On the other hand, time-series data such as accelerator output, electron beam amplitude, and conveyor speed in the electron beam irradiation device are constantly recorded as shown in FIG. The irradiation dose of the irradiation object to be sterilized by such an electron beam irradiation device can be estimated from the dose parameters such as the accelerator output, the electron beam amplitude, and the conveyor speed. Therefore, by comparing the electron beam irradiation start time t _P and the end time t _Q calculated as described above with the time series data of the dose parameter, whether the irradiation dose satisfies the specified amount within the irradiation time or not. Can be determined.

Further, the sensors 15 and 16 having a failure detecting function are used, and when one of them fails, the other one is activated, so that the production line is not stopped. The system can be made efficient.

[0024]

As described above, according to the present invention,
It is possible to measure the electron beam irradiation start time and end time almost accurately, so that the dose irradiated to the irradiation object at the electron beam irradiation time can be known almost accurately, and quality judgment with few errors is possible. At the same time, product quality assurance becomes easy. Further, since such a system can generally use the sensor installed in the sterilization chamber, it is possible to provide a reasonable system at a low cost. Also, by using a sensor having a failure detection function as such a sensor, an efficient system can be realized without stopping the production line.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a quality determination system for an electron beam irradiation apparatus according to an embodiment of the present invention.

FIG. 2 is a view of the electron beam irradiation region as seen from the side, (a)
6B is a side view at the start of electron beam irradiation, and FIG. 9B is a side view at the end of electron beam irradiation.

FIG. 3 is a graph showing various dose parameters and irradiation times.

FIG. 4 is a plan view showing a radiation region in the electron beam irradiation apparatus of this embodiment.

FIG. 5 is an overall schematic configuration diagram showing a conventional electron beam irradiation apparatus.

[Explanation of symbols]

10 Electron beam irradiation device 11 Irradiation object (product) 12A, 12B transport conveyor 14 irradiation conveyor 15 Cutout sensor 16, 23, 24 sensors 17 Stopper 18 Electron beam irradiation area 20 electron beams 25 Sterilization room 26 Sterilization room entrance 27 Sterilization chamber outlet

Claims (6)

[Claims] 1. A quality determination system for guaranteeing an electron beam dose applied to an irradiation object by an electron beam irradiation device for irradiating an electron beam to achieve an initial purpose such as sterilization. The electron beam irradiation start time and the irradiation end time are calculated from the time-series position information by one or more sensors arranged in the electron beam irradiation chamber on the upstream side or the downstream side of the electron beam irradiation region and the conveyor speed, It is characterized in that the electron beam dose of the electron beam irradiation apparatus is derived from its output information or the like in substantially synchronization with the serial position information, and it is determined whether or not a predetermined amount is held within the electron beam irradiation time. Quality determination system for electron beam irradiation equipment. 2. A quality judgment system for guaranteeing an electron beam dose applied to an irradiation object by an electron beam irradiation device for irradiating an electron beam to achieve an initial purpose such as sterilization. The electron beam irradiation start time and the irradiation end time are calculated from the time-series position information by the two or more sensors arranged in the electron beam irradiation chamber on the upstream side and the downstream side of the electron beam irradiation area and the conveyor speed, The electron beam dose of the electron beam irradiation apparatus is derived from its output information and the like in synchronism with the serial position information, and it is determined whether or not the electron beam dose holds a predetermined amount within the electron beam irradiation time. A quality determination system for an electron beam irradiation device, characterized by: 3. The quality determination system for an electron beam irradiation apparatus according to claim 1, wherein the sensor is installed at a position where the influence of the radiation generated by the irradiation of the electron beam is small. 4. The position where the sensor is installed is a position where the radiation strikes the sensor after being diffracted at least once, preferably once or twice. 2. The electron beam irradiation apparatus quality determination system according to 2. 5. A quality assurance of the electron beam irradiation apparatus, wherein a stopper and a cutout sensor are provided on the upstream side of the electron beam irradiation area, and the object to be irradiated passes through the electron beam irradiation area in close contact with each other. A quality determining system for an electron beam irradiation apparatus, wherein the sensor according to claim 1 or 2 is the cutout sensor. 6. A sensor comprising at least two sensors and having a failure detection function is used.
The quality determination system for an electron beam irradiation apparatus according to claim 1 or 2, wherein when one sensor fails, another sensor can be used.