System for electron and x-ray irradiation of product

• US 6,628,750 B1
• Filed: 11/09/2000
• Issued: 09/30/2003
• Est. Priority Date: 11/09/2000
• Status: Active Grant

• Current Assignee: Steris Corporation
• Original Assignee: Steris Corporation
• Inventors: Korenev, Sergey Alexandrovich
• Primary Examiner(s): Dunn, Drew A.
• Assistant Examiner(s): Kiknadze, Irakli
• Application Number:
  US09/710,475
• Time in Patent Office: 1,055 Days
• Field of Search: 250/453.11, 250/454.11, 250/455.11, 250/492.1, 250/492.3, 378/64, 378/68, 378/69, 378/92
• US Class Current: 378/64
• CPC Class Codes: G21K 5/04 with beam-forming means
• CPC Class Codes: G21K 5/10 with provision for relative movement of beam source and object to be irradiated

Abstract

A rotary accelerator (10) accelerates electrons and discharges them through each of a plurality of discharge ports, electrons discharge from each port having a different energy. The electron beams are channeled to scan horns disposed to irradiate products (14) traveling on conveyers (12). More specifically, some of the scan horns are positioned in pairs with an upper scan horn (18) on one side of the product, and a lower scan horn (20) on an opposite side of the product. A beam splitter splits the electron beam alternately between the two scan horns. Alternately, two scan horns (18, 20) are both disposed on the same side of the product. As yet another alternative, a scan horn (60) is disposed horizontally to irradiate the product from the side. Optionally, one or more of the scan horns includes a x-ray target (26) for converting the electrons into x-rays.

Claims

1. A product irradiation system comprising:

a shielded room;

a means for conveying a plurality of products concurrently through the shielded room;

a plurality of scan horns, at least one scan horn positioned for directing radiation into products conveyed on a corresponding conveyer;

an electron accelerator means for accelerating electrons to concurrently create a plurality of accelerated electron beams of different kinetic energies, the electron accelerator means including;

a means for accelerating electrons to a first level of kinetic energy,

a means for accelerating the first kinetic energy electrons to a second level of kinetic energy,

a means for accelerating the second kinetic energy electrons to a third level of kinetic energy,

a means for cyclically discharging pulses of beams of the first, second, and third levels of kinetic energy electrons;

a control means for directing the first, second, and third kinetic energy electron beams among the scan horns, such that each scan horn irradiates products with electrons of a one of the first, second, and third kinetic energies.

2. A product irradiation system comprising:

a shielded room;

a conveyer for conveying a plurality of products concurrently through the shielded room;

a first scan horn positioned for directing radiation into products conveyed on the conveyer;

a second scan horn positioned for directing radiation into the products conveyed on the conveyer, the first and second scan horns being positioned on opposite sides of the product to irradiate the product from opposite directions;

an electron accelerator for accelerating electrons to create both a first accelerated electron beam of a first kinetic energy and a second accelerated electron beam of a second kinetic energy different from the first kinetic energy;

a control for directing the first electron beam to the first scan horn and the second electron beam to the second scan horn to, to irradiate product concurrently with electron beams of different kinetic energies.

3. The product irradiation system as set forth in claim 2, wherein at least one of the scan horns include a heavy metal target for converting electron beam into x-rays.

4. A product irradiation system comprising:

a shielded room;

a plurality of conveyers for conveying a plurality of products concurrently through the shielded room;

at least two scan horns disposed to irradiate product on one of the conveyers, the two scan horns being offset from each other, such that each irradiates a different portion of the product;

an electron accelerator for accelerating electrons and emitting beams of electrons accelerated to at least two different energies;

a control for directing the electron beams concurrently to the scan horns, such that each of the scan horns irradiates the products with electron beams of one of the at least two energies.

5. The product irradiation system as set forth in claim 4, wherein the two scan horns are disposed on opposite sides of the product.

6. The product irradiation system as set forth in claim 5, wherein the controller directs electrons to the oppositely disposed scan horns alternately.

9. The product irradiation system as set forth in claim 4, further including a radiation detector disposed on an opposite side of the product from at least one of the scan horns for detecting an amount of received radiation, the radiation detector being connected with the controller.

7. A product irradiation system comprising:

a shielded room;

a plurality of conveyers for conveying a plurality of products concurrently through the shielded room;

a plurality of scan horns, at least one scan horn positioned for directing radiation into products conveyed on a corresponding conveyer;

an accelerator with output ports for generating electrons of each of a plurality of levels of kinetic energies, the scan horns receiving electrons of different kinetic energies;

a control for distributing the electrons of the plurality of energies among the scan horns, such that each of the scan horns irradiates product with electrons of selected energy.

8. The product irradiation system as set forth in claim 7, further including:

a product sensor for sensing when products are being irradiated, the sensor being connected with the controller such that the electrons are only distributed among the scan horns which are currently irradiating product.

10. The product irradiation system as set forth in claim 7, wherein at least some of the scan horns include a heavy metal target for converting the accelerated electrons into x-rays.

11. A product irradiation system comprising:

a shielded room;

a plurality of conveyors for conveying a plurality of products concurrently through the shielded room;

a plurality of scan horns, at least one scan horn positioned for directing radiation into products conveyed on each corresponding conveyer;

an electron accelerator for accelerating electrons to concurrently create a plurality of accelerated electron beams, each beam having electron pulses of characteristic electron kinetic energy and pulse duration;

an operator accessible control system that accesses a look up table to retrieve pre-determined beam characteristic values for optimum irradiation based on a user input dose input information for each conveyor, the values including;

the electron kinetic energy;

the electron beam pulse duration;

an electron beam repetition rate; and

a conveyer speed.

12. A method of irradiation comprising:

conveying products through an irradiation shielded region;

generating a plurality of beams of high kinetic energy electrons including;

generating electrons,

accelerating the generated electrons to a first level of kinetic energy,

accelerating the first level of kinetic energy electrons to a second, higher level of kinetic energy,

accelerating the second level of kinetic energy electrons to a third, higher level of kinetic energy;

concurrently scanning the accelerated electrons of at least two of the kinetic energy across the conveyed products.

13. The method as set forth in claim 12, further including converting at least some of the accelerated electrons to x-rays.

14. The method as set forth in claim 12, wherein the accelerated electrons irradiate opposite sides of the conveyed product alternately.

15. The method as set forth in claim 12, wherein the accelerated electrons are formed into a pulsed beam.

16. The method as set forth in claim 12 further including:

concurrently directing electrons of one of the energy levels to scan one conveyed product and electrons of a different one of the kinetic energy levels to scan another conveyed product.

17. A method of irradiation comprising:

passing a plurality of products on lines through an irradiation shielded region;

generating beams of higher kinetic energy electrons and beams of lower kinetic energy electrons;

dividing at least some of the beams into a pair of beams; and

,

scanning the electron beams across each line of products to be irradiated, with at least one of the pairs of beams irradiating a common product from opposite sides.

18. A method of irradiation comprising:

passing lines of products through an irradiation shielded region;

accelerating electrons to different kinetic energies;

dividing the accelerated electrons among a plurality of pulsed beams, at least some of the beams having electron pulses of different kinetic energy than other beams;

concurrently scanning the electron beams of different kinetic energy across the lines of products to be irradiated.

19. A method of irradiation comprising:

conveying products through an irradiation shielded region with different selected doses of radiation;

generating at least higher energy electron beams with pulses of higher kinetic energy electrons and lower energy electron beams with pulses of lower kinetic energy electrons;

controlling the dose by selecting;

a conveying speeds,

one of the higher and lower energy electron beams,

an electron pulse duration for each beam,

concurrently scanning the higher and lower energy electron beams across the conveyed products to be irradiated.

20. A method of product sterilization including:

manually inputting a product type into a product sterilization control;

assigning corresponding values to variables according to product thickness and type;

feeding the product through the sterilization system;

generating an electron beam;

controlling a kinetic energy of the electron beam according to the assigned variables;

irradiating the product with the electron beam.