Radionuclide calibrator responses for 224 Ra in solution and adsorbed on calcium carbonate microparticles.

A suspension of Ra-224 adsorbed onto CaCO3 micro-particles shows promise for alpha-therapy of intracavitary micrometastatic diseases. To facilitate accurate activity administrations, geometry-specific calibration factors for commercially available reentrant ionization chambers (ICs) have been developed for (RaCl2)-Ra-224 solutions and Ra-224 adsorbed onto CaCO3 microparticles in suspension in ampoules, vials, and syringes. Ampoules and vials give IC responses consistent with each other to <1%. Microparticles attenuation leads to a approximate to 1% to approximate to 2.5% reduction in response in the geometries studied.