Photoneutron spectra around an 18 MV LINAC |
| |
Authors: | Hector Rene Vega-Carrillo Antonio Baltazar-Raigosa |
| |
Institution: | (1) Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas, Zac., Mexico |
| |
Abstract: | Photoneutron spectra around an 18 MV LINAC were calculated in order to observe the effect produced by media around the accelerator.
Calculations were carried out with MCNP 4C code, three different cases were analyzed: Head model, Head and phantom model,
and Head, air, phantom and wall model. The spectra were calculated in five detectors located at the irradiation room at different
distances from the isocentre. A sixth detector, located near the entrance door was included to analyze how the maze change
the neutron spectrum. Neutrons are mainly produced in the LINAC head change the shape of evaporation neutrons from the source
term, some of these neutrons leak out the head with lesser energy, another neutrons goes with the treatment beam. At any site
near the isocentre neutron spectrum has evaporation and thermal neutrons joined by a set of epithermal neutrons. As the distance
from the isocentre increases evaporation neutrons tend to decrease while, epithermal and thermal neutrons tend to remain constant
regardless de distance due to room return produced by the walls. The maze contributes to reduce the neutron fluence, reducing
the evaporation neutrons; resulting spectrum is mainly the contribution of thermal and epithermal neutrons. Near the door
these neutrons can produce activation and prompt gamma rays. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|