SCALING PARAMETERS FOR HOT-PARTICLE BETA DOSIMETRY

• Published in: Radiation protection dosimetry Vol. 172; no. 4; p. 356
• Main Authors: Mangini, Colby D, Hamby, David M
• Format: Journal Article
• Language: English
• 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
• DOI: 10.1093/rpd/ncv529

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.