Characterization of Clinac-18 electron-beam energy using a magnetic analysis method.

Clinac-18 electron-beam energies and spectral energy distributions were measured by a magnetic analysis method to verify results obtained by the standard range method. A comparison of these measurements with nominal energies quoted by the manufacturer indicates that electron-beam measured by both methods are in agreement with the manufacturer's specifications to +/- 0.6 MeV. Spectral energy distribution of the electron beam was measured to be approximately 1 MeV (FWHM) at all energies.