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Neutron fluence and kerma spectra of a p (66)/Be(40) clinical source
Author(s) -
Jones D. T. L.,
Symons J. E.,
Fulcher T. J.,
Brooks F. D.,
Nchodu M. R.,
Allie M. S.,
Buffler A.,
Oliver M. J.
Publication year - 1992
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596922
Subject(s) - kerma , fluence , neutron , neutron flux , dosimetry , spectral line , neutron temperature , materials science , nuclear physics , neutron source , beam (structure) , irradiation , nuclear medicine , physics , optics , medicine , astronomy
High‐resolution neutron fluence spectra have been measured in the National Accelerator Centre's p (66)/Be(40) neutron therapy beam by the pulsed‐beam time‐of‐flight method. ICRU muscle kerma spectra have been derived from the fluence spectra. Spectral changes resulting from different irradiation conditions have been quantified in terms of the average neutron energy and the fractional low‐energy (<16 MeV) contribution. The changes observed with different thicknesses of polyethylene filtration are consistent with changes in quality parameters determined in biological and microdosimetric experiments. The dosimetry parameters( KA 150tissue ) Nand ( W gas ) N calculated for the measured spectra agree with the values recommended in the neutron dosimetry protocol. The shapes of the present fluence spectra differ from previous measurements of p (>40)/Be spectra. In particular, they differ significantly from the spectrum measured by recoil techniques in an identical neutron therapy unit at the Clatterbridge Hospital, UK. The reasons for the difference are not known.