Therapeutic radionuclides: beta radiation range

Abstract

In clinical practice, one of the most important determinants of effectiveness is the energy of beta radiation, which determines the range of particles and depth of penetration. This study was conducted to analyze the range of beta radiation of a radioactive isotope. The experiment used MCNPX to measure the variation of energy deposition with distance. For the source, 131I and 90Y were utilized, and for the energy analysis, the average energy, maximum energy, and continuous spectrum energy were assessed. First, for the range of 131I beta rays, the average energy was 0.5 mm, the maximum energy was 3.5 mm, and the spectrum source energy was 1.5 mm. Second, the for the range of 90Y beta rays, the average energy was 4.4 mm, the maximum energy was 11.4 mm, and the spectrum source energy was 7.8 mm. The range of spectrum energy is closer to the range of the actual source than the range of single energy. Third, the radiological range considering the average energy deposition (MeV/g) for 131I was concentrated at 82% at 0.1 mm, and the dose was 95% at 0.3 mm. For 90Y, the energy deposition was concentrated at 76% at 0.2 mm, and the dose was 95% at 1.0 mm. Energy deposition averaged based on radiation dose gives the highest dose in the first few millimeters. In the treatment with radionuclides, accurate and safe treatment can be performed only when the range of beta rays is considered, and determining the range values considering radiation dose as a spectral source will be more accurate than that using a single energy range.