Therapy Radiopharmaceuticals Practice Test

In alpha decay, the energy carried by the emitted alpha particle is determined by the nucleus itself and is not altered by the chemical form of the element. Ra-223 decays by emitting an alpha particle to produce Rn-219, and the alpha particle carries about 5.6–5.7 MeV of energy. This value is characteristic of the decay and applies whether Ra-223 is in dichloride or any other compound. The other options describe different radiation types or energies that don’t correspond to this decay: a beta energy would imply beta emission, which Ra-223 does not undergo; a 10 MeV gamma is not the primary radiation from this decay; and 3.5 MeV alpha is not the actual alpha energy for Ra-223. Therefore, the alpha energy is about 5.7 MeV.