Sterilization process for medical devices

• US 5,787,144 A
• Filed: 11/14/1996
• Issued: 07/28/1998
• Est. Priority Date: 11/14/1996
• Status: Expired due to Term

• Current Assignee: Ethicon Incorporated (Johnson & Johnson)
• Original Assignee: Ethicon Incorporated (Johnson & Johnson)
• Inventors: Findlay, Mark J.
• Primary Examiner(s): SCHEINER, LAURIE A
• Application Number:
  US08/748,874
• Time in Patent Office: 621 Days
• Field of Search: 378/69, 378/64, 426/240, 250/453.11, 250/454.11, 250/436, 250/437, 250/438, 250/482.1, 99/451
• US Class Current: 378/69
• CPC Class Codes: G21K 5/10 with provision for relative movement of beam source and object to be irradiated

Abstract

A radiation sterilization process for medical devices. The position of a CO₆₀ source is monitored during a sterilization process. If the CO₆₀ source moves out of the irradiation position, the central control unit moves the source down into a containment pool and stops the cycle timers. The source is then moved back up to the irradiation position and the cycle is restarted and the timers are restarted. The cycle time may be corrected using an algorithm.

Claims

1. Method of sterilizing a medical device by exposing the medical device to a CO₆₀ source for a sufficient amount of time to effectively sterilize the medical device during a sterilization cycle, wherein a CO₆₀ source is raised from a containment tank to an irradiation position and medical devices are transported past the source and the cycle timers time the cycle, the improvement comprising:

monitoring the position of the source during the cycle; and

lowering the source down into the containment tank if the source moves out of the irradiation position and simultaneously stopping the cycle timers; and

,

raising the source upward out of the containment tank into the irradiation position; and

,

restarting the cycle timers.

2. A method of sterilizing a medical device by exposing the medical device to a CO₆₀ source for a sufficient amount of time to effectively sterilize the medical device during a sterilization cycle, wherein a CO₆₀ source is raised from a containment tank to an irradiation position and medical devices are transported past the source and cycle timers time the source, the improvement comprising:

measuring the time for the source to move from the containment tank to the irradiation position;

monitoring the position of the source during the cycle;

lowering the source into the containment tank if the source moves out of the irradiation position and simultaneously stopping the cycle timers;

measuring the pause time of the source and the time of the movement of the source into the containment pool;

correcting the cycle time sufficiently to provide an effective dose of radiation by using the following algorithm to calculate a correction factor;

space="preserve" listing-type="equation">Correction Value=Td(Tmd+Tmu)/2;

wherein Td equals the measured pause time between detection of movement out of the irradiation position into a second position and the start of movement down form the second position into the containment pool;

Tmd equals the travel time of the source from the second position down into the containment pool to be completely submerged;

Tmu equals the travel time of the source up to the irradiation position from the containment pool;

allowing the timers to elapse the time equal to the correction value; and

,

raising the source out of the containment tank into the irradiation position and again starting the cycle timers and measuring and storing a new value of the time for the source to travel from the containment tank to the irradiation position.

3. A method of sterilizing a medical device by exposing the medical device to a CO₆₀ source for a sufficient amount of time to effectively sterilize the medical device during a sterilization cycle, wherein a CO₆₀ source is raised from a containment tank to an irradiation position and medical devices are transported past the source and cycle timers time the source, the improvement comprising:

measuring the time for the source to move from the containment tank to the irradiation position;

monitoring the position of the source during the cycle;

lowering the source into the containment tank if the source moves out of the irradiation position and simultaneously stopping the cycle timers;

measuring the pause time of the source and the time of the movement of the source into the containment pool;

correcting the cycle time sufficiently to provide an effective dose of radiation by using an algorithm to calculate a correction value based upon the measured times;

allowing the timers to elapse the time equal to the correction value; and

,

raising the source out of the containment tank into the irradiation position and again starting the cycle timers and measuring and storing a new value of the time for the source to travel from the containment tank to the irradiation position.