| Summary: | AIM: The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model <i>BrIccEmis</i> on dose point kernels (DPKs- radial dose distribution around a unit point source) and <i>S</i>-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely <sup>67</sup>Ga, <sup>80m</sup>Br, <sup>89</sup>Zr, <sup>90</sup>Nb, <sup>99m</sup>Tc, <sup>111</sup>In, <sup>117m</sup>Sn, <sup>119</sup>Sb, <sup>123</sup>I, <sup>124</sup>I, <sup>125</sup>I, <sup>135</sup>La, <sup>195m</sup>Pt and <sup>201</sup>Tl. METHODS: Radiation spectra were based on the nuclear decay data from the Medical Internal Radiation Dose (MIRD) RADTABS program and the <i>BrIccEmis</i> code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. <i>S</i>-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. RESULTS: The number of Auger and Coster Kronig (CK) electrons and X-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using <i>BrIccEmis</i>. DPKs for the electron spectra from <i>BrIccEmis</i> were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. <i>S</i>-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. CONCLUSION: Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.
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