Primary and leakage radiation calculations at 6, 10 and 25 MeV.

Primary and leakage x-ray spectra for typical clinical accelerators have been calculated using the EGS Monte Carlo code for 3 energies (6, 10 and 25 MeV) and 4 angles (0 degree, 45 degrees, 90 degrees and 135 degrees). Broad-beam transmission curves have been calculated for ordinary concrete using the MORSE program with the EGS spectra as input. A simple analytical model, which is shown to agree rather well with both experimental data and with the MORSE results, is presented and initial and subsequent tenth-value layers are extracted. Finally, the photon spectrum after the concrete shield is obtained with MORSE.