Seed loss in interstitial radiotherapy of prostatic carcinoma with I-125.

Incidence, extent, and time of seed loss after retropubic I-125 implantation was assessed in 52 patients treated for prostatic carcinoma. Radiographic controls up to 62 months were done to evaluate losses. Ninety percent of all patients lost seeds, averaging 8% of total implant number. Loss most frequently occurred within the first month by transurethral routes. Monitoring for seed loss is mandatory to assess dose deficit or inhomogeneous dose distribution, and to avoid environmental radiation hazards.