Characterisation of neutron fields around high-energy x-ray radiotherapy machines.
Photoneutron spectra around the treatment bed of a Varian Clinac 2100C machine were measured using a Bonner sphere spectrometer. To overcome problems with pulse pile-up and detection of non-neutron-induced events, the active detector of thermal neutrons normally used at the centre of the spheres was replaced by a sandwich of four CR-39 track detectors interleaved with 10B radiators. Track densities measured for the CR-39 detectors in Bonner spheres were used for the unfolding of neutron spectra. Neutron fluence and ambient dose equivalent for the whole energy range and partial energy intervals were derived from the neutron spectra.
Králík
M
M
Czech Metrology Institute, IIR, Radiova 1, CZ 102 00 Prague 10, Czech Republic. mkralik@cmi.cz
Turek
K
K
D000465:Algorithms; D001822:Body Burden; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods*; D006801:Humans; D009502:Neutrons; D016273:Occupational Exposure / Q000032:analysis*; D011785:Quality Assurance, Health Care / Q000379:methods; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011882:Radiotherapy, High-Energy / Q000009:adverse effects*; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods