A NEW METHOD FOR THE MEASUREMENT OF BREMSSTRAHLUNG SPECTRA

The x-ray energy spectrum from a 15 MeV linear accelerator (Siemens Mevatron 77/20) was determined combining attenuation and photoactivation analysis. The x-ray flux of the therapy linac is produced in a thick target and filtered through several materials. The theoretical expression for a thin-target spectrum was corrected for absorption in the target and materials in the accelerator head. The low-energy part of the spectrum was calculated from attenuation measurements and the high-energy part of the spectrum was determined by photoactivation.