Focal prostate brachytherapy with (103)Pd seeds

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Focal brachytherapy offers a potential alternative to whole-gland treatment for localized prostate cancer.
• Optimizing seed placement and target margins is crucial for effective focal brachytherapy.

Purpose of the Study:

• To examine necessary modifications in seed placement and target margins for focal brachytherapy using Palladium-103 ((103)Pd) seeds.
• To evaluate the feasibility of focal brachytherapy for intermediate-risk prostate cancer patients with a unilateral index lesion.

Main Methods:

• Utilized transperineal template-guided mapping biopsies (TTMB) to identify the index lesion in intermediate-risk patients.
• Incorporated TTMB core dimensions into 3-D ultrasound planning, expanding targets with margins.
• Planned implants to cover targets with 125Gy prescription dose, aiming for D90 between 125-150% and minimizing dose to organs at risk (OAR).

Main Results:

• A typical prostate gland required significantly fewer seeds and needles for hemi-prostate (39 seeds, 12 needles) and focal core (29 seeds, 8 needles) treatments compared to whole-gland.
• Tumicidal biologically effective dose (BED) was achieved for all cancerous target volumes.
• Dose constraints for organs at risk (urethra, rectum) were met, minimizing potential morbidity.

Conclusions:

• Focal brachytherapy with (103)Pd seeds can achieve target dosimetric goals and OAR constraints comparable to whole-gland treatments.
• This approach demonstrated a reduction in the number of seeds and needles required, suggesting potential for reduced toxicity.