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Efficient x‐ray tube simulations
Author(s) -
MainegraHing Ernesto,
Kawrakow Iwan
Publication year - 2006
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 - 10.1118/1.2219331
Subject(s) - bremsstrahlung , kerma , monte carlo method , radius , physics , photon , computational physics , x ray tube , half value layer , electron , dosimetry , tube (container) , optics , materials science , nuclear physics , mean free path , nuclear medicine , computer science , mathematics , statistics , medicine , computer security , electrode , anode , quantum mechanics , composite material
This article describes an efficiency study of directional bremsstrahlung splitting (DBS) for x‐ray tube modeling. DBS is shown to be up to five or six orders of magnitude more efficient at 50 or 135 kV tube potential than a simulation without splitting, and 60 times more efficient compared to uniform bremsstrahlung splitting. A methodology is presented to determine the optimum splitting number for a given situation using a second degree polynomial expression derived from theoretical considerations. Very large optimum splitting numbers are found for small fields ( 5 mm radius) at 1 m from the x‐ray source, which are relevant for half‐value layer (HVL) calculations and for simulations related to primary air kerma standards. Two approaches for the calculation of kerma at a plane and inside a volume using track‐length estimation are implemented in BEAMnrc, a user‐code from the EGSnrc Monte Carlo simulation system for photon and electron transport. A practical application of DBS to HVL calculations for a Comet MXR‐320 x‐ray tube is reported. The agreement with measured HVLs at different constant tube potentials is found to be better than 2.3%.