Photoneutron yield in steel shield by electron beam from medical linear accelerator

In recent years, many medical linear accelerators do not equip a beam stopper and such linacs generate not only high energy photons but high energy electrons. Therefore, there is possibility of shield necessity against bremsstrahlen and photoneutron generated by high energy electron beam. However, there are a few physical data or no recommendation. In this report, yield efficiency and leakage dose of bremsstrahlen and photoneutron was calculated using EGS Monte Carlo simulations. Then, to verify result by calculation, leakage dose by photoneutron was measured with a rem counter. The result clearly shows that leakage dose of bremsstrahlen and photoneutron generated by 15 MeV electron beam is negligible.