A system for the measurement of electron stopping powers: proof of principle using a pure β-emitting source

The accuracy of the electron stopping powers of elements and compounds is of great importance to medical dosimetry, radiation therapy, and radiation transport simulations. This paper summarises the commissioning of a new high purity Germanium (HPGe) detector and presents a feasibility study confirming the suitability of a method to determine electron stopping power data. A high-efficiency, HPGe detector was commissioned and found to match the manufacturer's performance specifications. A simple experiment was designed to obtain spectra acquired from a Sr-90/Y-90 radioactive check source with varying thicknesses of absorber (Al and Cu foils) placed between the source and the detector. The entire experimental arrangement was simulated using the EGSnrc radiation transport system. The Monte Carlo model of the detector accurately replicated the detector response to electrons and a quantitative analysis showed that the difference between the simulated and measured spectra was less than 1.5%, using the standard tabulated ICRU 37 stopping power data for the simulations. Based on the experiment with the low-energy Sr-90/Y-90 source, it is anticipated that this method can be used with a well-characterized quasi-monoenergetic electron beam, as available from a research linear accelerated to yield accurate measurements to validate current tabulated stopping power data.