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Neutron dosimetry for a general 252 Cf brachytherapy source
Author(s) -
Rivard Mark J.
Publication year - 2000
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 - 10.1118/1.1326445
Subject(s) - dosimetry , imaging phantom , neutron , fluence , materials science , neutron temperature , neutron source , brachytherapy , monte carlo method , neutron flux , optics , nuclear medicine , physics , irradiation , nuclear physics , medicine , radiation therapy , mathematics , radiology , statistics
This paper extends previous work to characterize neutron dosimetry in the vicinity of252 Cf brachytherapy sources. A general source is examined with an arbitrary length, diameter, and encapsulation using Monte Carlo methods. Fast neutron dosimetry and thermal neutron fluence rates were determined in a variety of clinically relevant media of varying dimensions. Applicator Tube, point source, high dose rate VariSource, and high dose rate μSelectron source geometries were analyzed. Fast neutron dosimetry was relatively independent of encapsulation thickness for an assortment of encapsulation materials less than 2 mm thick. Large variations in phantom size made minimal differences in the fast neutron dose close to the source. Specific source geometries were compared with dosimetry obtained from a simplified point model. The consequence of these results is a convenient means of accurately predicting clinical fast neutron dosimetry characteristics around a general252 Cf brachytherapy source in a variety of media without requiring neutron transport. Thermal neutron fluence rates were determined for a variety of source encapsulation materials, encapsulation thicknesses, and phantom sizes. At a distance of 3 cm from the source center, the thermal neutron fluence rate for a 30 cm diameter phantom was a 2.65 times greater than for a 10 cm diameter water phantom. These results demonstrate252 Cf thermal neutron fluence rate is relatively independent of encapsulation thickness and composition, yet highly dependent on hydrogen mass density and phantom size for phanta with diameters <30 cm.