Seed fixity in the prostate/periprostatic region following brachytherapy

Area of Science:

• Oncology
• Medical Physics
• Radiology

Background:

• Postoperative dosimetric analysis of prostate brachytherapy is common.
• Long-term seed persistence and migration after prostate brachytherapy are not well understood.
• Correlation between pelvic seed loss and lung embolization is largely uninvestigated.

Purpose of the Study:

• To evaluate the long-term fixity of implanted radioactive seeds (125I and 103Pd) in the prostate and periprostatic region.
• To assess the incidence of pelvic seed loss and its correlation with pulmonary seed embolization.

Main Methods:

• 175 patients undergoing prostate brachytherapy with 125I (95) or 103Pd (80) seeds were studied.
• Patients received a mean of 136 seeds using a modified uniform loading approach.
• CT scans, pelvic X-rays (day 0-502), and chest X-rays (for 156 patients) were used for analysis.

Main Results:

• Mean pelvic seed fixity exceeded 98% throughout the study period.
• Median seed loss was low: 1 seed for 125I and 2-3 seeds for 103Pd by 180 days.
• Pulmonary seed embolization occurred in 21.8% of patients, with higher incidence when chest X-rays were taken >30 days post-implant.

Conclusions:

• Prostate brachytherapy using 125I seeds in vicryl suture or 103Pd seeds ensures high seed fixity.
• The incidence of radioactive seed embolization to the lungs is low.
• Implantation of these seeds is safe for the prostate and surrounding tissues.