title: Photon contamination in 8-20-MeV electron beams from a linear accelerator.
abstract: The amount of x-ray contamination near the surface of a phantom irradiated with electron beams was measured directly. Measurements were done to ascertain if photon contamination in the beam contributes a higher dose to the more superficial layers of an irradiated medium than indicated by conventional methods. A 1.4-kG magnetic field was used to deflect the electron beams generated by a Philips SL/75-20 linear accelerator. The electron energies studied were 8, 10, 12, 14, 17, and 20 Mev. After sweeping the electron beam, a significant amount of photon contamination was measured in all cases. The characteristic qualities of the photon contamination were measured directly in a water tank. They were found to agree with those of bremsstrahlung spectra generated in a thin target with a virtual source at the location of the scattering foil.
mesh_terms: D004583:Electrons; D010315:Particle Accelerators; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy; D012542:Scattering, Radiation; D013679:Technology, Radiologic