Characteristics of brems Strahlung emissions from radionuclide therapy isotopes

Targeted radionuclide therapy uses radioisotopes that emit beta particles. Some of these isotopes also emit gamma lines that can be used to image the radiotracer distribution. In all these cases, the gammas detected by the SPECT camera are accompanied by a bremsstrahlung background. Here, we have performed several simulations and experiments in order to investigate the energy distribution and yields of the bremsstrahlung emissions for several radioisotopes used in radionuclide therapy. Different types of collimators were simulated, and the shape of the detected spectrum was compared with experiment, The simulations performed in this study strongly suggest that bremsstrahlung for non-pure beta emitters contribute little to the detected spectra.