Secondary exposure for 73 and 200 MeV proton therapy
Congress title :IM 2005 - European Workshop on Individual Monitoring of Ionising Radiation
Congress location :Vienne
Congress date :11/04/2005
Journal title : Radiation Protection Dosimetry Vol 125 issue 1-4 Pages : 349-354
Following modifications on the beam line at the Orsay Protontherapy Center, dose measurements were performed in order to make a dose map in the treatment rooms and in the delimited radiation-controlled area around beam line. Measurements were performed using tissue-equivalent proportional counters and rem-counters. Analysis of TEPC single event measurements showed that high LET components (>10 keV.µm-1) represent 90 to 99% of total dose equivalent in the treatment rooms and 50 to 90% in the controlled area and quality factors range, respectively between 2 and 15. A fast neutron component was identified in the treatment rooms, where dose equivalent rate varied between few µSv.h-1 to some dozen of mSv.h-1. In high-energy radiation field rem-counters underestimated TEPC values for neutron component. The variation between instruments response according to the location is linked to energetic spectrum variations and instrument characteristics.