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Modification of the 50% maximum dose depth for 41‐MeV ( p + ,Be) neutrons by use of filtration and/or transmission targets
Author(s) -
Smathers J. B.,
Graves R. G.,
Earls L.,
Otte V. A.,
Almond P. R.
Publication year - 1982
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 - 10.1118/1.595132
Subject(s) - beryllium , neutron , percentage depth dose curve , dosimetry , dose rate , materials science , radiation , radiochemistry , proton , filtration (mathematics) , equivalent dose , spectral line , cobalt 60 , neutron temperature , nuclear medicine , irradiation , nuclear physics , physics , chemistry , ionization chamber , mathematics , ionization , medicine , ion , statistics , quantum mechanics , astronomy
Several target configurations for the 41‐MeV ( p + ,Be) reaction have been evaluated for the characteristics of the radiation field produced; depth dose, dose rate per μA. From analysis, it is concluded that to achieve the desired 13.2‐cm depth for 50% of maximum dose and acceptable dose rate at a target‐to‐skin distance (TSD) of 125–150 cm, the neutron spectra must be filtered to preferentially absorb the lower‐energy neutrons. Further increases in depth of 50% of maximum dose and a significant reduction in beryllium heating problems result if a partial transmission target is used with the terminal 30% of proton energy being deposited in a copper target backing.