Determination of energy spectra in water for 6 MV X rays from a medical linac

Abstract

There is a lack of extensive data comprising energy spectra in water for beams generated by medical accelerators applied in radiotherapy. The purpose of this work was the determination of energy spectra in water for the 6 MV X-ray therapeutic beam from the medical linac — Clinac 2300 by Varian. The spectra were derived with the use of Monte Carlo computer simulations basing on MCNPX code in version of 2.7.0. The performed investigations indicate that shapes of the spectra as well as the mean Energy of the considered beams depend on a depth in water, a distance from the central-axis of the beam and a radiation field size. The obtained results are valuable for constructors of medical linacs and, additionally, they can be applied in advanced treatment planning systems. Therefore, all obtained spectra in a numerical form are available for common use. They will be sent to users after forwarding e-mail message to the authors of this paper.