Delivery system and prescription method for interstitial radiation therapy using enhanced parametric release sterilization techniques

• US 20050191207A1
• Filed: 11/12/2004
• Published: 09/01/2005
• Est. Priority Date: 11/19/2003
• Status: Active Grant

• Current Assignee: Theragenics Corporation (Juniper Investment Co. LLC)
• Original Assignee: Biocompatibles UK Limited (Boston Scientific Corporation)
• Inventors: Terwilliger, Richard A., Lamoureux, Gary A.
• Granted Patent: US 7,540,998 B2
• Time in Patent Office: Days
• US Class Current: 422/28
• CPC Class Codes: A61L 2/206 Ethylene oxide
• CPC Class Codes: A61N 2005/1011 Apparatus for permanent insertion of sources
• CPC Class Codes: A61N 5/1027 Interstitial radiation therapy

Abstract

A process is provided for sterilizing brachythearpy devices with Ethylene Oxide gas and releasing the devices on a parametric release basis. Devices that can be sterilized with this process include interstitial radiation seed strand implants and the needles used for implantation. In order to be sterilized effectively by EtO gas, the devices are constructed such that surfaces not readily infused with EtO gas are made to be gas permeable, and will not retain the gas after the sterilization process. Performance qualification of the sterilization process is performed through physical and microbiological studies, and set of established physical process parameters. Maintaining the physical process parameters in subsequent sterilization cycles will consistently yield the desired sterility assurance level without having to test the devices for sterility.

Claims

1. A method of sterilizing a brachytherapy device comprising the steps of:

packaging a brachytherapy device in a gas permeable package;

exposing the brachytherapy device and the package to a sterilizing gas;

sterilizing the brachytherapy device using a set of process parameters that repeatedly provide an appropriate level of sterilization; and

parametrically releasing the brachytherapy device from the sterilization process.

2. The method of claim 1 wherein the sterilizing step further comprises using at least one of the process parameters selected from the group consisting of load configuration, temperature, pressure, time, and gas concentration.

3. The method of claim 1 wherein the sterilizing step further comprises sterilizing and parametrically releasing the brachytherapy device, said brachytherapy device including a radioactive seed strand provided in a delivery needle.

4. The method of claim 1, the sterilizing step further comprising using ethylene oxide gas to sterilize the brachytherapy device.

5. The method of claim 1 including maintaining a temperature for the sterilization step between 45°

C. and 55°

6. A method for sterilizing a brachytherapy device comprising the steps of:

sterilizing the brachytherapy device using a set of process parameters that repeatedly provide an appropriate level of sterilization; and

parametrically releasing the brachytherapy device from the sterilization process.

7. A method for sterilizing a brachytherapy device with ethylene oxide gas comprising the steps of:

sterilizing the brachytherapy device with ethylene oxide gas using a set of process parameters that repeatedly provide an appropriate level of sterilization; and

parametrically releasing the brachytherapy device from the sterilization process.

8. A method of sterilizing at least one brachytherapy device, comprising steps of:

providing an open, sealable diffusion bag to contain said at least one brachytherapy device;

placing said at least one brachytherapy device into an interior of the open diffusion bag;

evacuating air from the diffusion bag;

sealing the diffusion bag;

positioning the diffusion bag in a chamber of a sterilizer having a ventilation system for removal of an exhaust gas from the chamber;

providing a sterilizing atmosphere in the interior of the diffusion bag by releasing into the diffusion bag ethylene oxide gas at a concentration sufficient to act as a sterilant;

heating ethylene oxide gas to an appropriate temperature;

maintaining the temperature of the ethylene oxide gas for a sufficient time to sterilize the at least one brachytherapy device.

9. The method of claim 8, including the step of selecting the diffusion bag constructed of a material that allows ethylene oxide gas to outwardly diffuse from the diffusion bag.

10. The method of claim 8, including the step of selecting the diffusion bag constructed of a tear-resistant material.

11. The method of claim 8, including the step of selecting the diffusion bag constructed of low density polyethylene.

12. The method of claim 8, including the step of selecting the diffusion bag being hermetically-sealed to form a substantially leak-proof seal.

13. The method of claim 8, including the step of releasing the ethylene oxide into the diffusion bag by a delivery mechanism.

14. The method of claim 13, including the step of choosing the delivery mechanism to be a cartridge containing ethylene oxide.

15. The method of claim 14, wherein the method further includes remotely activating the cartridge to release ethylene oxide gas.

16. The method of claim 8, wherein the method further comprises maintaining the temperature of ethylene oxide at about 45°

C. to about 55°

C.

17. The method of claim 8, further comprising a step of purging residual ethylene oxide gas from the diffusion bag for a sufficient time.

18. The method of claim 17, wherein the purging step duration is about 16 hours to 24 hours.

19. The method of claim 8, further comprising a step of placing said at least one brachytherapy seed strand and needle in a carrier prior to the step of placing said at least one brachytherapy seed strand and needle in the diffusion bag.

38. The method of claim 19, wherein the method further comprises selecting the carrier to be a plastic tray.

20. A method of sterilizing a brachytherapy device, the method comprising:

providing a gas permeable tray to contain said device;

placing said tray into a sealable diffusion bag;

sealing the diffusion bag;

positioning the diffusion bag in a chamber of a sterilizer having a ventilation system for removal of an exhaust gas from the chamber;

providing a sterilizing atmosphere in the interior of the diffusion bag by releasing into the diffusion bag ethylene oxide at gas a concentration sufficient to act as a sterilant;

heating the ethylene oxide to an appropriate temperature;

maintaining the temperature of the ethylene oxide gas for a sufficient time to sterilize the brachytherapy device and to complete the sterilization process;

conducting a performance qualification of the sterilization process through physical and microbiological studies;

extracting from the performance qualification a set of physical process parameters, which will consistently yield the desired sterility assurance level when said set of physical process parameters are maintained;

maintaining, monitoring, and recording the physical process parameters through direct analysis during routine processing;

repeating the sterilization process for subsequent brachytherapy devices and releasing the sterilized brachytherapy devices on parametric release.

21. The method of claim 20, wherein one of said physical process parameters is a load configuration.

22. The method of claim 20, wherein one of said physical process parameters is a sterilization temperature.

23. The method of claim 20, wherein one of said physical process parameters is a pressure in said chamber of the sterilizer.

24. The method of claim 20, wherein one of said physical process parameters is a cycle time for sterilization and purging.

25. The method of claim 20, wherein one of said physical process parameters is a gas concentration profile.

26. The method of claim 20, wherein the sterility assurance level is 10⁻

6.

27. The method of claim 20, wherein the brachytherapy device comprises a radioactive seed strand and a needle.

28. The method of claim 20, wherein the method includes selecting the diffusion bag to be constructed of a material that allows ethylene oxide outwardly to diffuse from the diffusion bag.

29. The method of claim 20, wherein the method includes selecting the diffusion bag to be constructed of a tear-resistant material.

30. The method of claim 20, wherein the method further includes selecting the diffusion bag to be constructed of low density polyethylene.

31. The method of claim 20, wherein the method includes selecting the diffusion bag to be hermetically-sealed to form a substantially leak-proof seal.

32. The method of claim 20, wherein the method includes releasing ethylene oxide into the diffusion bag by a delivery mechanism.

33. The method of claim 32, wherein the delivery mechanism is a cartridge containing ethylene oxide.

34. The method of claim 33, wherein the method further includes remotely activating the cartridge to release ethylene oxide gas.

35. The method of claim 20, further comprising maintaining the temperature of the ethylene oxide at about 45°

C. to about 55°

C.

36. The method of claim 20, further comprising a step of purging residual ethylene oxide gas from the diffusion bag for a sufficient time.

37. The method of claim 36, wherein the purging duration is about 16 to 24 hours.

39. A method of sterilizing a brachytherapy device using a gas diffusion process, comprising steps of:

providing an open, sealable diffusion bag to contain the item;

placing the item into an interior of the open diffusion bag;

evacuating air from the diffusion bag;

sealing the diffusion bag;

positioning the diffusion bag in a chamber of a sterilizer having a ventilation system for removal of exhaust gas from the chamber;

providing a sterilizing atmosphere in the interior of the diffusion bag by releasing into the diffusion bag ethylene oxide at a concentration sufficient to act as a sterilant;

heating ethylene oxide to an appropriate temperature;

maintaining the temperature of the ethylene oxide gas for a sufficient time to sterilize the item; and

removing the diffusion bag from the sterilizer after the item is sterilized.