Technical improvement in permanent seed implantation: a two-stage brachytherapy system. Description and comparison with current technique

Permanent seed implantation by available techniques has modest limitations. A new, two-stage needle design and technique is described and evaluated in comparison to a conventional permanent seed technique. The technique involves placing a stylet and sleeve initially into the all target coordinates prior to seed placement similar to temporary seed technique. The second stage involves consecutively removing the stylet from each sleeve and inserting a clear, plastic needle containing preloaded seeds into the sleeve and implanting the seeds. Fifty-six 125I patients were treated with the two-stage technique. Comparisons were made with a cohort of 71 patients implanted using a conventional technique at the Seattle Prostate Institute. Prostate movement, surgical time, catheterization rate, and DVH postop dosimetry were analyzed. After an initial learning curve, the two-stage technique had surgical times similar to conventional techniques. Cephalad movement of 3–10 mm was noted in 4 (8%) patients vs. 71 (100%) patients with our conventional technique. Of the 6 (10%) patients who required Foley catheterization, 3 (5%) did so for 1 day and 3 (5%) did so for less than 3 weeks. Day 1 CT scan based dosimetry was calculated on all patients. The V100 ranged from 80–100% with a median of 92.5%. For primary cases, the V100 (