IsoSphere

The IsoSphere is a spherical brachytherapy device designed to deliver radiation therapy to breast tumors after surgical resection. It consists of a 4 cm bioabsorbable PLA sphere containing radioactive seeds (Iodine-125 or Palladium-103) and spacers in multiple hollow channels, implanted permanently at the tumor bed to deliver prescribed radiation doses to residual tumor margins.

The IsoSphere differs from the predicate device by delivering multiple seeds and spacers in a single spherical implant rather than through multiple linear needle injections. Both use identical PLA material, radioactive isotopes (I-125 or Pd-103), sterilization method (ethylene oxide), and biocompatibility standards, and both are single-use permanent implants with 30-day shelf life.

ISO 10993-1 (biocompatibility for permanent implants), ANSI/AAMI ST72 (bacterial endotoxin), ISO 10993-11 (material-mediated pyrogens), ISO 11135 (ETO sterilization validation), ISO 10993-7 (EO residual testing), ISO 11607-1 & -2 (packaging performance), 49 CFR Part 173 (Type A transportation), ASTM F1886, F1929, F2824-10, F2051-00 (seal and performance integrity), and FDA guidance on MRI compatibility.

The device is substantially equivalent because it uses identical radioactive isotopes, materials, sterilization methods, and biocompatibility profile as the predicate, with all performance testing meeting predetermined criteria. Although the delivery geometry changed from linear needles to a single sphere, this design modification does not alter the fundamental therapeutic principle—delivering prescribed radiation to localized breast tumors—nor does it affect safety and effectiveness relative to the predicate device.