Radiant energy – Supported for nonsignalling objects of irradiation
Reexamination Certificate
1999-04-13
2001-01-23
Anderson, Bruce C. (Department: 2881)
Radiant energy
Supported for nonsignalling objects of irradiation
C250S492100
Reexamination Certificate
active
06177677
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an installation for the sterilization of medical products by irradiation.
2. Description of Related Art
It is known that tubes for extra-corporeal blood circulation, known as blood lines, which are used for extra-corporeal blood treatment, such as haemodialysis, undergo a sterilization process aimed at ensuring the complete elimination of germs. At the present time, this sterilization is carried out in various ways, for example by gamma-ray irradiation. However, this technique has various disadvantages linked to the dangerous nature of the material used for generating radiation, to the cost of shielding the irradiation equipment and to the difficulty in obtaining the official permits necessary for using it, in view of the growing awareness of environmental pollution. Moreover, high-temperature steam sterilization is unsuitable for PVC blood lines since, to ensure appropriate sterilization, it is necessary to employ a temperature near the softening point of PVC, thus entailing the risk of damage to the products.
At the present time, for further types of product, other irradiation methods are adopted, such as beta-ray irradiation, which do not cause the problems mentioned above. Beta-ray sterilization is, for example, used, with good results, for treating edible products or medical products of a non-critical nature.
However, where PVC blood lines are concerned, this sterilization treatment has not yet been used on a large scale due to the critical nature of the material and the stringent sterilization requirements demanded for such a use. In fact, on the one hand, the chemical and physical characteristics of PVC are extremely sensitive to irradiation doses and set strict upper limits to the doses which can be used and, on the other hand, the need for sufficient sterilization sets lower limits on these doses. Furthermore, irradiation installations which have not been designed specifically (such as third-party servicing installations) do not make it possible to ensure sufficient sterilization of the product as a whole, without some of the product being subjected to excessive exposure. In addition to this, the low unit price of the product makes it impossible to employ costly monitoring and management techniques if the competitiveness of blood lines sterilized by beta rays, as compared with lines sterilized by conventional methods, is to be maintained.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a sterilization installation which makes it possible to sterilize fragile products, such as PVC blood lines, efficiently and economically, without in any way damaging them.
In order to achieve this object, according to the invention an installation for the sterilization of medical products by irradiation is provided, characterized in that it comprises:
at least one product loading station,
at least one product unloading station,
an irradiation station located inside a containment having walls capable of stopping sterilizing radiation,
conveyance means for conveying the products to be sterilized from the loading station to the irradiation station and the sterilized products from the irradiation station to the unloading station, the conveyance means comprising grouping means for grouping the products to be sterilized in the vicinity of the irradiation station. Advantageously, the grouping means comprise a first conveyor and a second conveyor, the second conveyor being located immediately downstream of the first conveyor in relation to the direction of conveyance of the products and having a conveying speed lower than the conveying speed of the first conveyor.
According to a characteristic of the invention, the first and second conveyors comprise retractable drive members for catching the products and strictly subjecting their displacement to that of the corresponding conveyor.
According to a characteristic of the invention, the second conveyor comprises two half-conveyors separated by a gap located in a zone, towards which the irradiation station emits the sterilizing radiation.
According to a characteristic of the invention, the installation comprises a third conveyor located immediately downstream of the second conveyor in relation to the direction of conveyance of the products, the third conveyor having a conveying speed higher than the conveying speed of the second conveyor.
According to a characteristic of the invention, the conveyance means comprise
superposed conveyance sections, the conveyance sections located at a first level conveying the products to be sterilized from the loading station to the irradiation station and the conveyance sections located at a second level conveying the sterilized products from the irradiation station to the unloading station.
a vertical transporter for transferring the products from one conveyance level to the other conveyance level.
According to a characteristic of the invention, the installation comprises means for the detection of products, said detection means being arranged along the conveyance means, and control and monitoring means connected to the detection means in order to follow the travel of the products on the conveyance means.
According to a characteristic of the invention, the installation comprises a plurality of trays intended for supporting the products on the conveyance means, each tray being provided with an identification code, the means for the detection of products comprising code-reading means capable of reading the code affixed to each tray.
According to a characteristic of the invention, the means for the detection of products comprise code-reading means capable of reading an identification code affixed to each of the products arranged on each tray, and the control and monitoring unit is provided for combining and storing the identification code of each product and the identification code of the tray supporting this product.
According to a characteristic of the invention, the means for the detection of products comprise mechanical travel-limit detection means arranged inside the containment, in order to detect the position of the trays inside the containment and transmit a corresponding signal to the control and monitoring unit.
According to a characteristic of the invention, the invention comprises means for measuring the speed of the second conveyor which are connected to the control and monitoring means, and the control and monitoring means are provided for setting the irradiation emitted by the irradiation station as a function of the speed variations of the conveyor in such a way that the products receive a predetermined irradiation dose.
Another subject of the invention is a method for the sterilization of medical products by irradiation, comprising the steps of:
placing at least one product provided with a product identification code onto a tray provided with a tray identification code,
reading the tray identification code and the product identification code,
storing the combination of the tray and product identification codes,
conveying the tray along a definite path towards an irradiation station, and
locating the tray by reading the tray identification code at definite places along the path.
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Alboresi Luigi
Santi Marco
Anderson Bruce C.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hospal AG
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