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Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for 252 Cf medical sources
Author(s) -
Rivard Mark J.
Publication year - 1999
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 - 10.1118/1.598542
Subject(s) - dosimetry , neutron , neutron temperature , neutron source , materials science , nuclear engineering , nuclear physics , physics , radiochemistry , nuclear medicine , chemistry , medicine , engineering
252 Cf dosimetry was examined by calculative and experimental means. The Monte Carlo N ‐Particle (MCNP) transport code was used in a distributed computing environment (PVM) to determine neutron dose and neutron energy spectrum from252 Cf in a variety of clinically relevant materials. A Maxwellian spectrum was used to model252 Cf neutron emissions in these materials. Mixed‐field dosimetry of252 Cf applicator tube (AT) sources was measured using tissue‐equivalent ion chambers and a miniature GM counter to formulate a dosimetry protocol. Neutron dose was determined using the AAPM TG‐43 dosimetry protocol. Results demonstrate the overwhelming dependence of dosimetry on the source geometry and no significant neutron attenuation by the source or encapsulation. Gold foils and TLDs were used to measure thermal neutron flux near252 Cf AT sources and compared with MCNP results. The fast neutron energy spectrum did not change markedly at greater distances from the AT source. Calculations of moderated252 Cf neutron energy spectrum with various loadings of10 B and157 Gd were performed, in addition to analysis of neutron capture therapy dosimetry. Radiological concerns such as personnel exposure and shielding of252 Cf emissions were examined. Feasibility of a high specific‐activity HDR source was investigated through radiochemical and metallurgical studies using252 Cf stand‐ins such as Tb, Gd, and249 Cf . Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. At least 1 mg of252 Cf was necessary for a252 Cf HDR source.