Seed migration in prostate brachytherapy depends on experience and technique.

PURPOSE: To determine seed loss and pulmonary migration rate over time in permanent seed prostate brachytherapy. METHODS AND MATERIALS: We analyzed the first 495 patients treated in our department. All patients were treated with loose (125)I seeds with automated seed delivery system and real-time intraoperative planning. Pelvic fluoroscopic imaging was done 30 days after the implant. Patients were divided into five groups of 100 patients according to the order they were treated, and groups were compared using χ(2) test and one-way analysis of variance. RESULTS: A total of 22.8% of patients lost at least one seed. The highest percentage of patients losing any number of seeds was in the first 100. Thirty-eight percent lost at least one seed. This number decreased gradually and was only 9% in Patients 400-499. The mean total seed loss rate (number of seeds lost/number seeds implanted) changed significantly over time (p<0.001). There was a continuous significant (p<0.001) decline after the first 100 patients (1.25% for the first 100 patients) followed by a rise in Patients 300-399, followed by another decline (0.21% for the last 100 patients). The seed loss rate to the thorax changed significantly over time (p=0.009). It rose after an initial rate of 0.25-0.42% in Patients 200-299 and 300-399 and declined later to a rate of 0.21% in the last 100 patients. CONCLUSIONS: We found a learning curve for seed migration. Avoiding implanting seeds outside of the capsule and modern transrectal ultrasound imaging can help decrease migration.

Analysis of seed loss and pulmonary seed migration in patients treated with virtual needle guidance and robotic seed delivery.

PURPOSE AND BACKGROUND: To determine whether automated seed delivery system and real-time intraoperative (IO) virtual needle guidance reduce seed loss and pulmonary seed migration. PATIENTS AND METHODS: We analyzed 279 patients with low and intermediate risk prostate cancer treated in our institution with radioactive iodine (I-125) permanent seed implants. Loose seeds were exclusively used. To account for lost seeds, pelvic fluoroscopic imaging from 3 different angles was done 30 days after the implant. Posteroanterior and lateral chest x-rays were done when seed loss was confirmed. Patients were compared using the χ(2) test and Fisher exact test. RESULTS: At least 1 seed was lost in 31.5% of patients with a migration rate of 1.02%; 9.3% of patients had at least 1 seed in the lung with a migration rate of 0.22%. The population was divided into 3 groups according to the order in which they were treated. Seed loss (P=0.02) and pulmonary seed embolization (P=0.008) were significantly lower in the second hundred than in the first hundred patients. No difference was noted between groups 1 and 3 (patient, 201-279). Peri- or extracapsular seed placement was not correlated to seed loss (P=0.780 and P=0.092, respectively). No serious complications from seed migration were reported. Seed loss did not influence dosimetry parameters (V100, V150, and D90). CONCLUSION: Our pulmonary seed migration and total seed loss rates are comparable to the ones reported in the literature. Virtual needle guidance and automated seed delivery system are in our hand as accurate as the manual technique.