Method and apparatus for validation of sterilization process

• US 20050135965A1
• Filed: 12/23/2003
• Published: 06/23/2005
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• Current Assignee: Baxter International Inc.
• Original Assignee: Baxter International Inc.
• Inventors: Martine, John A. Jr., Williams, John A.
• Granted Patent: US 7,641,851 B2
• Time in Patent Office: Days
• US Class Current: 422/58
• CPC Class Codes: A61L 2/087 Particle radiation, e.g. electron-beam, alpha or beta radiation
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation
• CPC Class Codes: A61L 2/28 Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour apparatus involving enzymes or microorganisms C12M1/34; methods involving enzymes or microorganisms C12Q1/00
• CPC Class Codes: A61L 2202/122 Chambers for sterilisation
• CPC Class Codes: A61L 2202/14 Means for controlling sterilisation processes, data processing, presentation and storage means, e.g. sensors, controllers, programs
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps

Abstract

An apparatus, system and method for verifying the achievement of a desired sterility assurance level (SAL) for components manipulated within a low-energy electron beam sterilization chamber. The components are preferably pre-sterilized and connected together in an assembly fashion which creates and maintains the sterility of the connection by subjecting the components to low-energy (less than 300 KeV) electron beam radiation. The verification is completed by measuring the sterilization dose delivered to a sensor, also known as a dosimeter, positioned within the sterilization process to simulate the components.

Claims

1. A method for verifying sterilization of components in a sterilization system using a low-energy electron-beam comprising the steps of:

placing a component to be sterilized within a low-energy electron-beam sterilization system onto a component pallet;

determining a minimum sterilization dose which when applied to the component results in a desired sterility assurance level (SAL);

attaching an indicator within the sterilization system as a site to be used to indicate achievement of at least the minimum sterilization dose;

establishing a correlation between a sterilization dose at the component and a dose at the indicator;

exposing the component and indicator to a sterilizing source;

determining the dose at the indicator; and

ascertaining the efficacy of the sterilization dose achieved at the component based on the determined dose at the correlated indicator.

2. The method of claim 1, wherein the step of establishing a correlation comprises the steps of:

exposing the component and a plurality of indicators to a sterilizing source to mimic operation of a sterilization system;

measuring the dose received at each indicator; and

repeating exposing and measuring steps until a mathematical relationship between the sterilization dose measured at the component and a dose measured at least one indicator is found.

3. The method of claim 1, wherein the sterilization dose of the step of exposing the component and indicators to a sterilizing source is administered by an electron beam.

4. The method of claim 1, wherein the step of determining the level of the dose at the indicator is achieved by a sensor.

5. The method of claim 4, wherein the sensor is a radiation dosimeter.

6. The method of claim 1, wherein the indicator comprises a dosimeter.

7. The method of claim 1, wherein the indicator comprises a plurality of dosimeters.

8. The method of claim 1, wherein the indicator is detachably affixed to the pallet.

9. The method of claim 7, wherein the dosimeters are detachably affixed to the pallet.

10. A radiation sterilization verification device comprising:

a dosimeter; and

a first dosimeter block comprising an interior surface with a cavity defined therein wherein the dosimeter is positioned within the cavity.

11. The device of claim 10, further comprising:

a second dosimeter block comprising an interior surface with a protrusion configured to abut an interior surface of the cavity of the first dosimeter block; and

a mechanism to affix the first dosimeter block to the second dosimeter block to form an assembly.

12. The device of claim 10, further comprising a mechanism to affix the first dosimeter block to a radiation sterilization site.

13. The device of claim 11, further comprising a mechanism to affix the assembly to a radiation sterilization site.

14. The device of claim 13, wherein the mechanism to affix the first dosimeter block to the second dosimeter block comprises the mechanism to affix the assembly to a radiation sterilization site.

15. The device of claim 11, wherein the mechanism to affix the first the first dosimeter block to the second dosimeter block comprises friction.

16. The device of claim 10, wherein the first dosimeter block comprises a single cavity.

17. The device of claim 11, wherein the first dosimeter block comprises a plurality of cavities, and wherein the second dosimeter block has a corresponding number of protrusions configured to abut an interior surface of a cavity.

18. The device of claim 11, further comprising a passage defined within either the first or second dosimeter block to allow radiation to reach the cavity.

19. The device of claim 10, further comprising a passage defined within the first dosimeter block to allow radiation to reach the cavity.

20. The device of claim 18, wherein a diameter of the passage is in the range of from about 4.45 mm (0.175 inch) to about 7.37 mm (0.290 inch).

21. The device of claim 20, wherein the diameter of the passage is about 5.94 mm (0.234 inch).

22. The device of claim 18, wherein a depth of the passage is in the range of from about 1.78 mm (0.070 inch) to about 4.45 mm (0.175 inch).

23. The device of claim 22, wherein the depth of each passage is about 3.15 mm (0.124 inch).

24. The device of claim 17, further comprising a plurality of passages defined within either the first or second dosimeter block to allow radiation to reach each cavity.

25. The device of claim 24, wherein a diameter of each passage is in the range of from about 4.45 mm (0.175 inch) to about 7.37 mm (0.290 inch).

26. The device of claim 25, wherein the diameter of each passage is about 5.94 mm (0.234 inch).

27. The device of claim 24, wherein a depth of each passage is in the range of from about 1.78 mm (0.070 inch) to about 4.45 mm (0.175 inch).

28. The device of claim 27, wherein the depth of each passage is about 3.15 mm (0.124 inch).

29. A system for verifying the sterility of components comprising:

a sterilization chamber;

a pallet member configured to position a component within the sterilization chamber;

a dosimeter holder having a dosimeter contained therein and detachably affixed to the pallet member;

a low-energy sterilization source configured to deliver a sterilization dose to a component and a correlated dose to the dosimeter within the sterilization chamber;

a verification station for measuring the correlated dose absorbed by the dosimeter within the sterilization chamber.

30. The system of claim 29, further comprising at least two components positioned on the pallet member and an actuator which drives at least one of the components while in the sterilization chamber to effect connection between the components.

31. The system of claim 29, wherein the dosimeter holder comprises a passage permitting radiation to reach the contained dosimeter.

32. The system of claim 29, wherein the verification station comprises a colorimeter.

33. A radiation sterilization verification device comprising:

a plurality of dosimeters; and

a first dosimeter block comprising an interior surface with a plurality of cavities defined therein wherein a dosimeter is positioned within each cavity.

34. The device of claim 33, further comprising:

a second dosimeter block comprising an interior surface with a plurality of protrusions each configured to abut an interior surface of one of the plurality of cavities of the first dosimeter block; and

a mechanism to affix the first dosimeter block to the second dosimeter block to form an assembly.

35. The device of claim 33, further comprising a mechanism to affix the first dosimeter block to a radiation sterilization site.

36. The device of claim 34, further comprising a mechanism to affix the assembly to a radiation sterilization site.

37. The device of claim 36, wherein the mechanism to affix the first dosimeter block to the second dosimeter block comprises the mechanism to affix the assembly to a radiation sterilization site.

38. The device of claim 34, wherein the mechanism to affix the first the first dosimeter block to the second dosimeter block comprises friction.

39. The device of claim 34, further comprising a passage defined within either the first or second dosimeter block to allow radiation to reach the cavity.

40. The device of claim 33, further comprising a passage defined within the first dosimeter block to allow radiation to reach the cavity.

41. The device of claim 39, wherein a diameter of the passage is in the range of from about 4.45 mm (0.175 inch) to about 7.37 mm (0.290 inch).

42. The device of claim 41, wherein the diameter of the passage is about 5.94 mm (0.234 inch).

43. The device of claim 39, wherein a depth of the passage is in the range of from about 1.78 mm (0.070 inch) to about 4.45 mm (0.175 inch).

44. The device of claim 43, wherein the depth of each passage is about 3.15 mm (0.124 inch).

45. An assembly for verifying sterilization of components, the assembly comprising:

a component pallet configured to carry at least one component, a portion of which at least one component requires sterilization;

a component site defined by the portion of the at least one component requiring sterilization, the site requiring a threshold sterilization dose to achieve sterility of the portion of the at least one component; and

a dosimeter holder positioned approximate the component site and having at least one dosimeter to receive an applied dose which corresponds to a sterilization dose received by the component site.

46. The assembly of claim 45, wherein the component pallet is configured to carry at least two components to be connected together to form a set, and wherein a portion of the at least two components define the component site.

47. The assembly of claim 46, wherein the first component pallet is configured to carry a plurality of components to be connected to at least one other component to form a plurality of sets, and wherein a portion of each component being connected to form a set defines a component site such that the number of sets is equal to the number of component sites.

48. The assembly of claim 45, wherein the component pallet comprises a means for controlling the dose received by the dosimeter of the dosimeter holder.

49. The assembly of claim 48, wherein the means for controlling the dose received by the dosimeter comprises an aperture in the dosimeter holder having a diameter and a depth.

50. The assembly of claim 49, wherein the diameter of the aperture is in the range of from about 4.45 mm to about 7.37 mm.

51. The assembly of claim 49, wherein the depth of the aperture is in the range of from about 1.78 mm to about 4.45 mm.

52. The assembly of claim 45, wherein the dosimeter holder comprises:

a first block having a cavity defined within a wall to contain a dosimeter therein, and an aperture, having a diameter and depth, through the wall within the periphery of the cavity; and

a second block configured with a mating section which fits within the cavity of the first block to abut the dosimeter therein.

53. The assembly of claim 45, wherein the dosimeter holder comprises:

a first block having a cavity defined within a wall to contain a dosimeter therein; and

a second block configured with a mating section which fits within the cavity of the first block to abut the dosimeter therein, and an aperture, having a diameter and depth, through the mating section.

54. The assembly of claim 47, wherein the dosimeter holder comprises:

a first block having a plurality of cavities defined within a wall to each contain a dosimeter therein; and

a second block configured with a mating section for each cavity of the first block to abut the dosimeter therein, and an aperture, having a diameter and depth, through each mating section.

55. The assembly of claim 54, wherein the number of cavities is equal to the number of component sites.

56. The assembly of claim 54, wherein the ratio of cavities to component sites is within the range of from 1:

1 to 4;

1.

57. The assembly of claim 52, wherein the second block is configured to fasten to the first block.

58. The assembly of claim 52, wherein the diameter and depth of the aperture is selected to permit a sterilization dose level at the dosimeter which is proportionate to a desired sterilization dose level at the component securing site.

59. The assembly of claim 58, wherein the diameter of the aperture is in the range of from about 4.45 mm to about 7.37 mm.

60. The assembly of claim 58, wherein the depth of the aperture is in the range of from about 1.78 mm to about 4.45 mm.

61. The assembly of claim 45, wherein the component pallet comprises from 1 to 10 component sites and from 1 to 15 dosimeters.

62. The assembly of claim 47, wherein the component pallet comprises from 1 to 10 component sites and from 1 to 15 dosimeters.