Brachytherapy
Sealed radioactive source placement inside or adjacent to tumor — prostate (LDR seeds or HDR), cervix/uterus (HDR tandem-and-ovoid, tandem-and-ring), breast (Mammosite, SAVI), skin, eye plaques. Delivers very high dose to target with extremely rapid falloff. Distinct discipline from external beam; different workflow, different regulatory footprint (NRC byproduct license).
Clinical pathway
HDR gynecologic: applicator placement under ultrasound or CT guidance, CT or MRI planning scan, contouring and optimization (typically TG-43 or model-based dose calc), treatment delivery via Ir-192 afterloader (e.g., Elekta Flexitron, Varian BRAVOS) — 5–15 min delivery; applicator removal.
LDR prostate seeds: I-125 or Pd-103 seed implant under TRUS guidance in OR, real-time or post-implant dosimetry.
HDR prostate: catheter placement in OR, CT/MRI planning, afterloader treatment over 1–3 fractions.
Typical systems
- Elekta Flexitron (HDR afterloader)
- Varian BRAVOS (HDR afterloader)
- Dedicated brachy planning suites (Oncentra, BrachyVision)
Room + procedure characteristics
- Suite requirements: shielded vault, remote afterloader, emergency source-retraction procedures, dedicated CT or MRI access
- Team: radiation oncologist, medical physicist (required onsite during treatment per NRC), nursing, anesthesia for gyne cases
- Regulatory: NRC or Agreement State byproduct license, Part 35.400 sealed-source provisions