Methods for Measuring Vacuum Level of Evacuated Vials Used in Nuclear Medicine Applications

Most commercial ⁹⁹Mo/ ⁹⁹mTc generators use column chromatography, in which ⁹⁹Mo is adsorbed onto alumina (Al₂O₃) and provides a means for obtaining of sodium pertechnetate (^99mTc). The procedures for elution of ^99mTc are designed to provide a sterile, pyrogen free product suitable for human injection or for elaboration into other radiopharmaceutical preparations. In addition to the generator itself a variety of accessories will be required during the elution. These include sterile isotonic saline solution used as the eluent and sterile vials to hold the eluate. These vials have been evacuated and this vacuum will serve to draw the saline through the generator. The volume of eluted radioactivity is controlled by the size of the evacuated vial used and/ or by the supply of isotonic saline solution provided in the vial attached to the inlet spike. Potential problems with column generator systems are poor elution due to loss of the vacuum on the evacuated vial. To ensure that the vacuum level has maintained its stability at the time of deployment, the vacuum must remain intact within acceptable limits. Vacuum level testing by Tesla-Gun and FMS-1400P Headspace Pressure Analyzer can measure vacuum levels in evacuated vial in a rapid and non-destructive manner. The study demonstrated the non-destructive analytical methods by Tesla-Gun and FMS-1400P Headspace Pressure Analyzer for investigating evacuated vial integrity. The methods overcome many of the limitations of destructive analytical methods. These results may be used to determine what level of initial pressure level is acceptable for a given sterile evacuated vials at the time of supply with the ⁹⁹Mo/ ^99mTc generators. (author)