Practical considerations in the selection of seed strength for prostate implants

Area of Science:

• Urology
• Radiation Oncology
• Medical Physics

Background:

• Prostate seed implants are a common treatment for localized prostate cancer.
• Optimizing seed strength can potentially improve procedural efficiency and dosimetry.

Purpose of the Study:

• To investigate the use of higher activity seeds (~0.7 U) in prostate brachytherapy compared to standard seeds (0.4 U).
• To evaluate the impact of higher seed strength on procedural time, dosimetry, and long-term patient outcomes.

Main Methods:

• A comparative study involving twenty consecutive prostate cancer patients undergoing brachytherapy.
• Ten patients received implants with 0.4 U seeds, and ten received implants with ~0.7 U seeds.
• Postimplant dosimetry, operative time, and long-term toxicity (urinary, rectal, erectile function) were assessed.

Main Results:

• Implants using ~0.7 U seeds required over 30% fewer seeds and eight fewer needles.
• Total theatre time showed a small, insignificant decrease with higher strength seeds.
• Mean D90 was marginally lower and more variable with 0.7 U seeds; rectal wall doses were slightly higher.
• Six-year postimplant symptom scores for toxicity and function were similar between groups.

Conclusions:

• Higher activity seeds (0.7 U) offer procedural advantages in prostate brachytherapy by reducing seed and needle count.
• Long-term clinical outcomes and toxicity profiles are comparable between 0.4 U and 0.7 U seed implants.
• Practical considerations for selecting seed strength in prostate brachytherapy are discussed.