Evaluation of bremsstrahlung X-rays when beta radiation from beta-forbidden transitions is stopped in thick targets

In this study, algebraic expressions obtained by folding together beta radiation energy distributions for selected forbidden transitions with an algebraic representation of the bremsstrahlung distribution from monoenergetic electrons have been derived and used to obtain bremsstrahlung energy distributions when beta radiation is stopped in a thick attenuator. Results are compared with results from Monte Carlo simulations using the code Electron Gamma Shower (EGSnrc). There are some differences between the results, but the simulations with EGSnrc agree quite well with the algebraic calculations for the bremsstrahlung energy distributions from the first and second forbidden beta transition within an acceptable range of uncertainty. Also the algebraic calculations for a representative beta spectrum are compared with the beta spectral data from ICRU 56, Dosimetry of External Beta Rays for Radiation Protection, and the algebraic calculations for the bremsstrahlung energy distribution are compared with the data from bremsstrahlung spectra from electrons from the “Atomic Data and Nuclear Data Tables 35”. There is acceptable agreement in both of the comparison results.