Abstract
This study aimed at improving and extending results of our previous study on corrections for conventional neutron dose meters used in environments with high-energy neutrons (E > 10 MeV). Moderated-type neutron dose meters tend to underestimate the dose contribution of high-energy neutrons because of the opposite trends of dose conversion coefficients and detection efficiencies as the neutron energy increases. A practical correction scheme has been proposed based on analysis of hundreds of neutron spectra and more than 50 kinds of neutron detectors in the IAEA-TRS-403 report. By comparing 252Cf-calibrated dose responses with reference values derived from fluence-to-dose conversion coefficients, this study provided recommendations for neutron field characterization and the corresponding dose correction factors. Further sensitivity studies addressed three important issues. (1) If the spectral correction factors are independent of the selection of three commonly used calibration sources: 252Cf, 241Am-Be, 239Pu-Be or other commonly-used calibration sources? (2) If the derived correction factors for different sizes of moderated-type neutron dose meters, such as Bonner spheres of various sizes (6” to 9”), are similar in trend? (3) If the derived correction factors for different kinds of neutron detectors, such as different type survey instruments or other detectors with different principle, are still applicable? Finally, use the proton accelerator of Chang Gung Hospital, the first proton therapy center in Taiwan as an example, to confirm the feasibility of spectral correction factors in the practical application.