Chemical properties

Ra-224 is usually in divalent state.

Nuclear properties

Ra-224 decays by ɑ decay with a half-life of 3.6316(23) days. Its decay chain involving Rn-220 (T_1/2 = 55.6(1) s), Po-216 (T_1/2 = 145(2) ms), Pb-212 (T_1/2 = 10.622(7) h), Bi-212 (T_1/2= 60.55(6) min), either Po-212 (T_1/2 = 0.29 µs) or Tl-208 (T_1/2 = 3.053(4) min) leads to stable Pb-208. Including its decay chain, the cumulative ɑ emission is 400% per Ra-224 decay with an average ɑ energy of 6.75 MeV.

Ra-224 and daughters emit γ rays and X rays. Notable emissions are from Ra-224 at 241.0 keV (4.10(5)%), Pb-212 at 238.6 keV (43.6(5)%), Bi-212 at 727.3 keV (6.67(9)%) and Tl-208 at 2614.5 keV (99.754(4)%) and 583.2 keV (85.0(3)%).

Production

Ra-224 is produced by high energy proton induced spallation of thorium targets with subsequent off-line mass separation at the CERN MEDICIS facility. The mass-separated ions are implanted into a solid matrix, e.g., a NaCl layer on Al or Al layer on Au metal backing.

Distribution

Ra-224 is shipped from CERN MEDICIS. Activity will be shipped from there to the users in liquid (0.05-0.1 M HCl) form or as solid, implanted in NaCL layer or Al layer on metallic foil.

Examples of use

• Ra-224 can serve in Pb-212 generators to provide Pb-212 that is used in turn as in-vivo Pb-212/Bi-212 generator. Different Ra-224/Pb-212 generator designs such as REF,REF,REF have been studied.
• Free Ra²⁺ ions act, analogously to Ca²⁺, as bone seekers. Ra-224 administered as chloride has been used clinically to treat ankylosing spondylitis REF.
• Ra-224 sources can serve for “Diffusing Alpha-Emitter Radiation Therapy” REF.