[en] Image analyzer system and collimator has been successfully applied to calibrate simultaneously multiple ¹²⁵I seeds in a sterile cartridge. Seeds within the cartridge were placed on an imaging plate, and the imaging plate irradiated. To remove scatter radiation, and improve spatial resolution of seed images, this study used a specially designed collimator. The irradiated imaging plate was scanned using an image analyzer system, and radioactivity intensities of seed images were given in counts. Counts could be translated to profiles, and each seed within the cartridge was analyzed. It is observed that a good correlation between counts and total radioactivity of the seeds within the cartridge. Thus, using a least-squares line, it was possible to calibrate a seed with unknown apparent activity. By analyzing the profiles, it was possible not only to detect a mis calibrated seed in the cartridge from its relative difference in counts, but also to identify its position in the cartridge. Using an imaging analyzer system, all seeds in a cartridge could be calibrated in a sterile environment. (author)