SCALING PARAMETERS FOR HOT-PARTICLE BETA DOSIMETRY

Scaling of dose-point kernel (DPK) values for beta particles transmitted by high-Z sources will overestimate dose at shallow depths while underestimating dose at greater depths due to spectral hardening. A new model has been developed based on a determination of the amount of monoenergetic electron...

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Bibliographic Details
Published inRadiation protection dosimetry Vol. 172; no. 4; p. 356
Main Authors Mangini, Colby D, Hamby, David M
Format Journal Article
LanguageEnglish
Published England 01.12.2016
Subjects
Beta Particles
Brachytherapy - methods
Computer Simulation
Electrons
Humans
Monte Carlo Method
Neoplasms - radiotherapy
Radiometry - methods
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted - methods
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Summary:Scaling of dose-point kernel (DPK) values for beta particles transmitted by high-Z sources will overestimate dose at shallow depths while underestimating dose at greater depths due to spectral hardening. A new model has been developed based on a determination of the amount of monoenergetic electron absorption that occurs in a given source thickness through the use of EGSnrc (Electron Gamma Shower) Monte Carlo simulations. Integration over a particular beta spectrum provides the beta-particle DPK following self-absorption as a function of source thickness and radial depth in water, thereby accounting for spectral hardening that may occur in higher-Z materials. Beta spectra of varying spectral shapes and endpoint energies were used to test the model for select source materials with 7.42 ≤ Z ≤ 94. The results demonstrate that significant improvements can be made to DPK-based dosimetry models when dealing with high-Z volumetric sources. This new scaling model is currently being used to improve the accuracy of the beta-dosimetry calculations in VARSKIN 5.
ISSN:1742-3406
DOI:10.1093/rpd/ncv529