Ponente
Descripción
One of the currant tasks of Working Group 9 (WG9: Radiation dosimetry in Radiotherapy) of EURADOS (The European Radiation Dosimetry Group) is to characterize the spectrum of the neutron parasitic field originated as a consequence of radiotherapy. This neutron field may affect patient organs outside the treatment volume, leading to unwanted doses which potentially produce unwanted radiation effects, but do not have any therapeutical benefit. This task has been already running for several years, and activities of WG9 in the past included measurements in photon therapy facilities. Nowadays, its main activity has concentrated in characterizing radiation fields in proton therapy facilities, including measurements of neutron spectra in the treatment room and in-patient dosimetry.
In this work, we will present preliminary results of neutron spectra measured in the HIT (Heidelberg, Germany) facility, when irradiating phantoms to proton, Helium, Carbon and Oxygen beams of energies appropriate to mimic treatment of a brain tumour in an anthropomorphic paediatric phantom. Measurements were performed in the forward beam direction, after the phantom, where the primary ions were stopped. Neutron spectra were determined from adequate unfolding of measurements performed with a set of Bonner Spheres, containing a He-3 detector at their centre. The main features of the spectra obtained will be discussed and compared to former proton irradiations.
