The TheraSeed radioactive seed implant (Theragenics Corporation; now owned by Bard Medical) is used to deliver low-level radiation to the prostate to treat cancer. The TheraSeed radioactive seed is a relatively small implant comprised of a titanium tube with two graphite pellets and a lead marker inside. The outside dimensions of tube are approximately 0.177-inches in length with a diameter of 0.032-inches.
Palladium-103 is the isotope contained in the TheraSeed implant. Because the radiation is so low and the seeds are placed so precisely, virtually all the radiation is absorbed by the prostate. Treatments with the TheraSeed implant may involve placement in the prostate of from 80 to 120 of these devices. These “seeds” are implanted with “spacers” between them and placed according to treatment plans, so that they do not contact one another during their intended “in vivo” use.
Magnetic resonance tests (magnetic field interactions, heating, and artifacts) conducted on the TheraSeed revealed that this implant is acceptable for patients undergoing MR procedures at 3-Tesla or less.